<SEC-DOCUMENT>0001193125-12-006886.txt : 20120110
<SEC-HEADER>0001193125-12-006886.hdr.sgml : 20120110
<ACCEPTANCE-DATETIME>20120109185824
ACCESSION NUMBER:		0001193125-12-006886
CONFORMED SUBMISSION TYPE:	S-3/A
PUBLIC DOCUMENT COUNT:		2
FILED AS OF DATE:		20120110
DATE AS OF CHANGE:		20120109

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ARROWHEAD RESEARCH CORP
		CENTRAL INDEX KEY:			0000879407
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-COMMERCIAL PHYSICAL & BIOLOGICAL RESEARCH [8731]
		IRS NUMBER:				460408024
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0930

	FILING VALUES:
		FORM TYPE:		S-3/A
		SEC ACT:		1933 Act
		SEC FILE NUMBER:	333-178073
		FILM NUMBER:		12518491

	BUSINESS ADDRESS:	
		STREET 1:		201 SOUTH LAKE AVENUE
		STREET 2:		SUITE 703
		CITY:			PASADENA
		STATE:			CA
		ZIP:			91101
		BUSINESS PHONE:		626-304-3400

	MAIL ADDRESS:	
		STREET 1:		201 SOUTH LAKE AVENUE
		STREET 2:		SUITE 703
		CITY:			PASADENA
		STATE:			CA
		ZIP:			91101

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	INTERACTIVE GROUP INC
		DATE OF NAME CHANGE:	20020509

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	INTERACTIVE INC
		DATE OF NAME CHANGE:	19940224
</SEC-HEADER>
<DOCUMENT>
<TYPE>S-3/A
<SEQUENCE>1
<FILENAME>d258445ds3a.htm
<DESCRIPTION>AMENDMENT NO. 1 TO FORM S-3
<TEXT>
<HTML><HEAD>
<TITLE>Amendment No. 1 to Form S-3</TITLE>
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<h5 align="left"><a href="#toc">Table of Contents</a></h5>

  <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>As filed with the Securities and Exchange Commission on January 9, 2012
</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>Registration Statement No.&nbsp;333-178073 </B></FONT></P>
<P STYLE="font-size:4px;margin-top:0px;margin-bottom:0px">&nbsp;</P> <P STYLE="line-height:0px;margin-top:0px;margin-bottom:0px;border-bottom:0.5pt solid #000000">&nbsp;</P>
<P STYLE="line-height:3px;margin-top:0px;margin-bottom:2px;border-bottom:0.5pt solid #000000">&nbsp;</P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="5"><B>UNITED STATES </B></FONT></P>
<P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="5"><B>SECURITIES AND EXCHANGE COMMISSION </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT
STYLE="font-family:Times New Roman" SIZE="3"><B>Washington, D.C. 20549 </B></FONT></P><center> <P STYLE="line-height:6px;margin-top:0px;margin-bottom:2px;border-bottom:1pt solid #000000;width:21%">&nbsp;</P></center>
<P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="5"><B>Amendment No. 1 </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT
STYLE="font-family:Times New Roman" SIZE="5"><B>to </B></FONT></P>  <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="5"><B>FORM S-3 </B></FONT></P>
<P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="5"><B>REGISTRATION STATEMENT </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT
STYLE="font-family:Times New Roman" SIZE="3"><B><I>UNDER </I></B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="3"><B><I>THE SECURITIES ACT OF 1933 </I></B></FONT></P><center>
<P STYLE="line-height:6px;margin-top:0px;margin-bottom:2px;border-bottom:1pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="6"><B>ARROWHEAD
RESEARCH CORPORATION </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>(Exact name of Registrant as Specified in Its Charter) </B></FONT></P>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P><center> <P STYLE="line-height:6px;margin-top:0px;margin-bottom:2px;border-bottom:1pt solid #000000;width:21%">&nbsp;</P></center>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
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<TD VALIGN="top" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>Delaware</B></FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>46-0408024</B></FONT></TD></TR>
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<TD VALIGN="top" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>(State of Incorporation)</B></FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>(I.R.S. Employer Identification Number)</B></FONT></TD></TR></TABLE>
<P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>225 South Lake Avenue, Suite 300 </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT
STYLE="font-family:Times New Roman" SIZE="2"><B>Pasadena, CA 91101 </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>626-304-3400 </B></FONT></P>
<P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>(Address, including zip code and telephone number, including area code, of Registrant&#146;s principal executive offices)
</B></FONT></P> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P><center> <P STYLE="line-height:6px;margin-top:0px;margin-bottom:2px;border-bottom:1pt solid #000000;width:21%">&nbsp;</P></center>
<P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>Christopher Anzalone, Chief Executive Officer </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT
STYLE="font-family:Times New Roman" SIZE="2"><B>Arrowhead Research Corporation </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>225 South Lake Avenue, Suite 300
</B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>Pasadena, CA 91101 </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT
STYLE="font-family:Times New Roman" SIZE="2"><B>626-304-3400 </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>(Name, address, including zip code and telephone number,
including area code, of agent for service) </B></FONT></P> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P><center>
<P STYLE="line-height:6px;margin-top:0px;margin-bottom:2px;border-bottom:1pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B><I>Copies to:
</I></B><B> </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>Ryan Murr </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT
STYLE="font-family:Times New Roman" SIZE="2"><B>Ropes&nbsp;&amp; Gray LLP </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>Three Embarcadero Center </B></FONT></P>
<P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>San Francisco, CA 94111 </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT
STYLE="font-family:Times New Roman" SIZE="2"><B>(415) 315-6300 </B></FONT></P> <P STYLE="margin-top:6px;margin-bottom:0px"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>Approximate Date of Commencement of Proposed Sale to the Public:</B>
From time to time after this Registration Statement becomes effective, as determined by the Selling Stockholders. </FONT></P> <P STYLE="margin-top:6px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">If the only
securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, please check the following box.&nbsp;&nbsp;&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT> </FONT></P>
<P STYLE="margin-top:6px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the
Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box.&nbsp;&nbsp;&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#120;</FONT> </FONT></P>
<P STYLE="margin-top:6px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">If this Form is used to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the
following box and list the Securities Act Registration Statement number of the earlier effective registration statement for the same offering.&nbsp;&nbsp;&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT> </FONT></P>
<P STYLE="margin-top:6px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the
Securities Act Registration Statement number of the earlier effective registration statement for the same offering.&nbsp;&nbsp;&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT> </FONT></P>
<P STYLE="margin-top:6px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">If this Form is a registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become
effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box.&nbsp;&nbsp;&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT> </FONT></P>
<P STYLE="margin-top:6px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">If this Form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register
additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box.&nbsp;&nbsp;&nbsp;&nbsp;<FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT> </FONT></P>
<P STYLE="margin-top:6px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller
reporting company. See the definitions of &#147;large accelerated filer,&#148; &#147;accelerated filer&#148; and &#147;smaller reporting company&#148; in Rule&nbsp;12b-2 of the Exchange Act. </FONT></P>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
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<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Large&nbsp;accelerated&nbsp;filer</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2"><FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">Accelerated&nbsp;filer</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2"><FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT></FONT></TD></TR>
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<TD VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Non-accelerated filer</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2"><FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT>&nbsp;(Do not check if a smaller reporting company)</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">Smaller&nbsp;reporting&nbsp;company</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2"><FONT STYLE="FONT-FAMILY:WINGDINGS">&#120;</FONT></FONT></TD></TR>
</TABLE>   <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P><center> <P STYLE="line-height:6px;margin-top:0px;margin-bottom:2px;border-bottom:1pt solid #000000;width:21%">&nbsp;</P></center>
<P STYLE="margin-top:6px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>The registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until
the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section&nbsp;8(a) of the Securities Act of 1933, as amended, or until the Registration
Statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section&nbsp;8(a), may determine. </B></FONT></P> <P STYLE="font-size:8px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<P STYLE="line-height:0px;margin-top:0px;margin-bottom:0px;border-bottom:0.5pt solid #000000">&nbsp;</P> <P STYLE="line-height:3px;margin-top:0px;margin-bottom:2px;border-bottom:0.5pt solid #000000">&nbsp;</P>

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<h5 align="left"><a href="#toc">Table of Contents</a></h5>

 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT STYLE="font-family:Arial Narrow" SIZE="2" COLOR="#de1a1e"><B>The information in this prospectus is not complete and may be changed. We may not sell these
securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any state where the
offer or sale is not permitted. </B></FONT></P> <p STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P>  <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT
STYLE="font-family:Times New Roman" SIZE="2" COLOR="#de1a1e"><B>Subject to Completion, dated&nbsp;January 9, 2012 </B></FONT></P>  <P STYLE="margin-top:6px;margin-bottom:0px"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>Prospectus
</B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="6"><B>Arrowhead Research Corporation </B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px" ALIGN="center"><FONT
STYLE="font-family:Times New Roman" SIZE="4"><B>1,597,072 shares of Common Stock </B></FONT></P> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P><center>
<P STYLE="line-height:6px;margin-top:0px;margin-bottom:2px;border-bottom:1pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:6px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">This prospectus
covers the sale of an aggregate of 1,597,072 shares of our Common Stock, $0.001 par value per share (the &#147;Shares&#148;), by the selling security holders identified in this prospectus (collectively with any holder&#146;s transferee, pledgee,
donee or successor, the &#147;<B>Selling Stockholders</B>&#148;). The Shares covered by this prospectus were issued in a private placement with closings on September&nbsp;30, 2011 and October&nbsp;5, 2011 (the &#147;<B>Private Placement</B>&#148;).
</FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">The Company will not receive any proceeds from the sale by the Selling Stockholders of the Shares. We are paying the cost of
registering the Shares covered by this prospectus as well as various related expenses. The selling stockholders are responsible for all selling commissions, transfer taxes and other costs related to the offer and sale of their shares. </FONT></P>
<P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">Sales of the Shares by the Selling Stockholders may occur at fixed prices, at market prices prevailing at the time of sale, at prices
related to prevailing market prices, or at negotiated prices. The selling stockholders may sell shares to or through underwriters, broker-dealers or agents, who may receive compensation in the form of discounts, concessions or commissions from the
selling stockholders, the purchasers of the shares, or both. If required, the number of shares to be sold, the public offering price of those shares, the names of any underwriters, broker-dealers or agents and any applicable commission or discount
will be included in a supplement to this prospectus, called a prospectus supplement. </FONT></P>  <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">The Company&#146;s Common Stock is
traded on The NASDAQ Capital Market under the symbol &#147;ARWR.&#148; On January 6, 2012, the closing sale price of our Common Stock on The NASDAQ Capital Market was $5.29 per share. Our principal executive offices are located at 225&nbsp;South
Lake Avenue, Suite&nbsp;300, Pasadena, California 91101, and our telephone number is (626)&nbsp;304-3400. </FONT></P>
<P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B><I>Investing in our securities involves a high degree of risk. You should carefully consider the <A HREF="#toc258445_4">Risk
Factors</A> beginning on page 2 before you invest in our securities. </I></B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>Neither the Securities and Exchange
Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense. </B></FONT></P>
<P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>  <P STYLE="margin-top:12px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>The date of this prospectus is
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;, 2012 </B></FONT></P>

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<h5 align="left"><a href="#toc">Table of Contents</a></h5>

 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B><A NAME="toc"></A>Table of Contents </B></FONT></P>
<P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
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<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2"><A HREF="#toc258445_1">ABOUT THIS PROSPECTUS</A></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">1</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;</FONT></TD></TR>
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<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2"><A HREF="#toc258445_2">SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS</A></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">1</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;</FONT></TD></TR>
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<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2"><A HREF="#toc258445_3">ABOUT THE COMPANY</A></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">2</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;</FONT></TD></TR>
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<TD HEIGHT="8" COLSPAN="4"></TD></TR>
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<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2"><A HREF="#toc258445_4">RISK FACTORS</A></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">2</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;</FONT></TD></TR>
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<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2"><A HREF="#toc258445_5">USE OF PROCEEDS</A></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">3</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD></TR>
<TR>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2"><A HREF="#toc258445_6">SELLING SECURITYHOLDERS</A></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">3</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD></TR>
<TR>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2"><A HREF="#toc258445_7">PLAN OF DISTRIBUTION</A></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">4</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD></TR>
<TR>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2"><A HREF="#toc258445_8">EXPERTS</A></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">6</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD></TR>
<TR>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2"><A HREF="#toc258445_9">LEGAL MATTERS</A></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">6</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD></TR>
<TR>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2"><A HREF="#toc258445_10">WHERE YOU CAN FIND MORE INFORMATION</A></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">6</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD></TR>
<TR>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2"><A HREF="#toc258445_11">INCORPORATION OF CERTAIN INFORMATION BY REFERENCE</A></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">7</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;</FONT></TD></TR>
</TABLE>

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<h5 align="left"><a href="#toc">Table of Contents</a></h5>

 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B><A NAME="toc258445_1"></A>ABOUT THIS PROSPECTUS </B></FONT></P>
<P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">You should read this prospectus, any applicable prospectus supplement and the information incorporated by reference in this prospectus
before making an investment in the securities of Arrowhead Research Corporation. See &#147;Where You Can Find Additional Information&#148; for more information, page 6. You should rely only on the information contained in or incorporated by
reference in this prospectus or a prospectus supplement. The Company has not authorized anyone to provide you with different information. This document may be used only in jurisdictions where offers and sales of these securities are permitted. You
should assume that information contained in this prospectus, or in any document incorporated by reference, is accurate only as of any date on the front cover of the applicable document. Our business, financial condition, results of operations and
prospects may have changed since that date. </FONT></P>  <P STYLE="margin-top:24px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B><A NAME="toc258445_2"></A>SPECIAL NOTE REGARDING FORWARD-LOOKING
STATEMENTS </B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">This prospectus contains forward-looking statements within the meaning of the federal securities laws. You can
identify forward-looking statements by the use of the words &#147;believe,&#148; &#147;expect,&#148; &#147;anticipate,&#148; &#147;intend,&#148; &#147;estimate,&#148; &#147;project,&#148; &#147;will,&#148; &#147;should,&#148; &#147;may,&#148;
&#147;plan,&#148; &#147;intend,&#148; &#147;assume&#148; and other expressions which predict or indicate future events and trends and which do not relate to historical matters. You should not rely on forward-looking statements, because they involve
known and unknown risks, uncertainties and other factors, some of which are beyond the control of the Company. These risks, uncertainties and other factors may cause the actual results, performance or achievements of the Company to be materially
different from the anticipated future results, performance or achievements expressed or implied by the forward-looking statements. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT
STYLE="font-family:Times New Roman" SIZE="2">Factors that might cause these differences include the following: </FONT></P> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="9%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="3%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">the integration of multiple technologies and programs; </FONT></P></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="9%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="3%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">the ability to successfully complete development and commercialization of products and the Company&#146;s expectations regarding market growth;
</FONT></P></TD></TR></TABLE> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="9%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="3%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">the cost, timing, scope and results of ongoing safety and efficacy trials of preclinical and clinical testing; </FONT></P></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="9%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="3%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">the ability to successfully complete product research and further development; </FONT></P></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="9%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="3%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">the volume and profitability of product sales of future products; </FONT></P></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="9%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="3%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">changes in existing and potential relationships with corporate collaborators and partners; </FONT></P></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="9%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="3%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">the availability, cost, delivery and quality of materials supplied by contract manufacturers; </FONT></P></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="9%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="3%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">the timing, cost and uncertainty of obtaining regulatory approvals of our products; </FONT></P></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="9%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="3%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">the ability to obtain substantial additional funding; </FONT></P></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="9%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="3%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">the ability to develop and commercialize products before competitors that are superior to the alternatives developed by competitors;
</FONT></P></TD></TR></TABLE> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="9%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="3%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">the ability to retain certain members of management; </FONT></P></TD></TR></TABLE> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>

<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="9%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="3%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">the Company&#146;s expectations regarding research and development expenses and general and administrative expenses; </FONT></P></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="9%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="3%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">the Company&#146;s expectations regarding cash balances, capital requirements, anticipated revenue and expenses, including infrastructure expenses;
</FONT></P></TD></TR></TABLE> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="9%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="3%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">our belief regarding the validity of our patents and potential litigation; and </FONT></P></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="9%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="3%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">other factors detailed from time to time in filings with the Securities and Exchange Commission. </FONT></P></TD></TR></TABLE>
 <p STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">1 </FONT></P>


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 <P STYLE="margin-top:0px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">In addition, the factors described under the section captioned &#147;Risk Factors&#148; in
this prospectus, as may be updated from time to time by our future filings under the Securities Exchange Act, and elsewhere in the documents incorporated by reference in this prospectus, may result in these differences. You should carefully review
all of these factors. These forward-looking statements were based on information, plans and estimates at the date of this prospectus, and we assume no obligation to update any forward-looking statements to reflect changes in underlying assumptions
or factors, new information, future events or other changes. </FONT></P> <P STYLE="margin-top:24px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B><A NAME="toc258445_3"></A>ABOUT THE COMPANY </B></FONT></P>
<P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2"><I>Unless otherwise noted, (1)&nbsp;the term &#147;Arrowhead Research&#148; refers to Arrowhead Research Corporation, a Delaware
corporation, formerly known as InterActive Group, Inc., (2)&nbsp;the terms &#147;Arrowhead,&#148; the &#147;Company,&#148; &#147;we,&#148; &#147;us,&#148; and &#147;our,&#148; refer to the ongoing business operations of Arrowhead and its
subsidiaries, whether conducted through Arrowhead Research or a subsidiary of the company, and (3)&nbsp;the term &#147;Common Stock&#148; refers to shares of Arrowhead Research&#146;s Common Stock and the term &#147;stockholder(s)&#148; refers to
the holders of Common Stock or securities exercisable for Common Stock. </I></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">Arrowhead Research Corporation is a nanomedicine
company developing innovative therapeutic products at the interface of biology and nanoengineering to cure disease and improve human health. Arrowhead addresses its target markets through ownership in subsidiaries that are selected based on
synergies in their technology, and clinical and business strategies. By focusing on specific related applications of nanomedicine, Arrowhead and its subsidiaries leverage shared expertise and resources to develop pioneering therapeutic platforms for
large unmet medical needs. Arrowhead is a leader in delivering small RNAs for gene silencing, and has programs in anti-obesity therapeutics and regenerative medicine. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT
STYLE="font-family:Times New Roman" SIZE="2">Arrowhead&#146;s portfolio includes Arrowhead Madison, an RNAi therapeutics research company, two majority owned subsidiaries, Calando Pharmaceuticals, Inc., a leader in delivering small RNAs for gene
silencing and Ablaris Therapeutics, Inc. (&#147;Ablaris&#148;), an anti-obesity therapeutics company and minority investments in Nanotope, Inc., a regenerative medicine company and Leonardo Biosystems, Inc., a multistage drug delivery company.
</FONT></P>  <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">Our common stock is listed on the Nasdaq Capital Market under the symbol &#147;ARWR&#148;. </FONT></P>
<P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">Our executive offices are located at 225 South Lake Avenue, Suite 300, Pasadena CA 91101 and our telephone number is (626)&nbsp;304-3400.
Additional information regarding our company, including our audited financial statements and descriptions of our business, is contained in the documents incorporated by reference in this prospectus. See &#147;Where You Can Find More
Information&#148; on page&nbsp;6 and &#147;Incorporation of Certain Information by Reference&#148; on page&nbsp;
7. </FONT></P>  <P STYLE="margin-top:24px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B><A NAME="toc258445_4"></A>RISK FACTORS </B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT
STYLE="font-family:Times New Roman" SIZE="2">We are a development-stage company and we have limited historical operations. Before making an investment decision, you should carefully consider the risks described in the sections entitled &#147;Risk
Factors&#148; in our most recent Annual Report on Form 10-K and subsequent Quarterly Reports on form 10-Q, as filed with the SEC, which are incorporated herein by reference in their entirety, as well any amendment or updates to our risk factors
reflected in subsequent filings with the SEC, including the applicable prospectus supplement. Our business, financial condition or results of operations could be materially adversely affected by any of these risks. The trading price of our
securities could decline due to any of these risks, and you may lose all or part of your investment. This prospectus and the incorporated documents also contain forward-looking statements that involve risks and uncertainties. Our actual results
could differ materially from those anticipated in these forward-looking statements as a result of certain factors, including the risks mentioned elsewhere in this prospectus. </FONT></P> <P STYLE="margin-top:18px;margin-bottom:0px"><FONT
STYLE="font-family:Times New Roman" SIZE="2"><B><I>We recently acquired significant assets from Roche related to RNAi technologies, and Roche retains a right of first negotiation over certain candidates developed based on the acquired RNAi
technologies. </I></B></FONT></P> <P STYLE="margin-top:6px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">On October&nbsp;21, 2011, we entered into a Stock and Asset Purchase Agreement with Hoffmann-La Roche
Inc. and F.&nbsp;Hoffmann-La&nbsp;Roche Ltd, pursuant to which we purchased from Roche (i)&nbsp;all of the outstanding common </FONT></P>
 <p STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">2 </FONT></P>


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 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT STYLE="font-family:Times New Roman" SIZE="2">
stock of Roche Madison Inc. and (ii)&nbsp;the intellectual property rights currently held by Roche related to its RNAi business and identified in the RNAi Purchase Agreement. Pursuant to the RNAi
purchase agreement, Roche has a limited right of first negotiation on certain product candidates developed by us relating to the purchased assets.&nbsp;This right of first negotiation applies to all three Existing Candidates (disease targets
previously studied by Roche) and to up to five other drug candidates that we may develop. The right of first negotiation could delay the process of entering into a strategic relationship related to any product candidates developed based on the
acquired RNAi technologies and could adversely impact our ability to attract a partner or acquirer for any such product candidates and could negatively impact the prospects for a larger company to acquire Arrowhead. </FONT></P>
<P STYLE="margin-top:24px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B><A NAME="toc258445_5"></A>USE OF PROCEEDS </B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT
STYLE="font-family:Times New Roman" SIZE="2">The proceeds from the resale of the Shares under this prospectus are solely for the account of the Selling Stockholders. We will not receive any proceeds from the sale of Shares under this prospectus.
</FONT></P> <P STYLE="margin-top:24px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B><A NAME="toc258445_6"></A>SELLING SECURITYHOLDERS </B></FONT></P>
<P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">The Company has included in this prospectus 1,597,072 shares of Common Stock issued upon the closing of the Private Placement.
</FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">In connection with the Private Placement, we have agreed to file a registration statement with the Securities and Exchange
Commission covering the resale of the Private Placement Shares. </FONT></P>  <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">The following table sets forth certain information
regarding the Selling Stockholders and the shares of Common Stock beneficially owned by them, which is based on information that is available to us as of January&nbsp;6, 2012. Selling Stockholders may offer shares under this prospectus from time to
time and may elect to sell none, some or all of the shares set forth next to their name. As a result, we cannot estimate the number of shares of Common Stock that a Selling Stockholder will beneficially own after termination of sales under this
prospectus. In addition, a Selling Stockholder may have sold, transferred or otherwise disposed of all or a portion of that holder&#146;s shares of Common Stock since the date on which they provided information for this table. We have not made
independent inquiries about this. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">Beneficial ownership is determined in accordance with the rules and regulations of the SEC
and includes voting or investment power with respect to our common stock. Shares of our common stock subject to options or warrants that are currently exercisable or exercisable within 60&nbsp;days of January&nbsp;6, 2012 are considered outstanding
and beneficially owned by the person holding the options or warrants for the purpose of calculating the percentage ownership of that person but not for the purpose of calculating the percentage ownership of any other person. </FONT></P>
<P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">The Company implemented a 1 for 10 reverse split of its common stock on November&nbsp;17, 2011. All share amounts have been adjusted to
reflect post-split amounts and percentages of beneficial ownership are based on 10,525,941 common shares issued and outstanding as of January&nbsp;6, </FONT></P>
 <p STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">3 </FONT></P>


<p Style='page-break-before:always'>
<HR  SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">
<h5 align="left"><a href="#toc">Table of Contents</a></h5>

  <P STYLE="margin-top:0px;margin-bottom:0px"><FONT STYLE="font-family:Times New Roman" SIZE="2">
2012. Shares not outstanding but deemed beneficially owned by virtue of the right of a person to acquire them as of January 6, 2012, or within sixty days of such date, are treated as outstanding
only when determining the&nbsp;percentage owned by such individual and when determining the percentage owned by a group of which such individual is a member. </FONT></P>  <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT
STYLE="font-family:Times New Roman" SIZE="2">We are relying on written commitments from the Selling Stockholders to notify us of any changes in their beneficial ownership after the date they originally provided this information. See &#147;Plan of
Distribution&#148; beginning on page 5. </FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE" ALIGN="center">


<TR>
<TD WIDTH="55%"></TD>
<TD VALIGN="bottom" WIDTH="6%"></TD>
<TD style="width:1pt"></TD>
<TD></TD>
<TD></TD>
<TD style="width:1pt"></TD>
<TD VALIGN="bottom" WIDTH="6%"></TD>
<TD style="width:9pt"></TD>
<TD></TD>
<TD></TD>
<TD style="width:9pt"></TD>
<TD VALIGN="bottom" WIDTH="7%"></TD>
<TD style="width:1pt"></TD>
<TD></TD>
<TD></TD>
<TD style="width:1pt"></TD>
<TD VALIGN="bottom" WIDTH="7%"></TD>
<TD style="width:20pt"></TD>
<TD></TD>
<TD></TD>
<TD style="width:20pt"></TD></TR>
<TR>
<TD VALIGN="bottom" NOWRAP STYLE="border-bottom:1px solid #000000"> <P STYLE="margin-top:0px;margin-bottom:1px"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>Selling Security Holder(1)</B></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom" COLSPAN="4" ALIGN="center" STYLE="border-bottom:1px solid #000000"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B># of Shares</B></FONT><br><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>held before</B></FONT><br><FONT
STYLE="font-family:Times New Roman" SIZE="1"><B>Offering</B></FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" COLSPAN="4" ALIGN="center" STYLE="border-bottom:1px solid #000000"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>#&nbsp;Shares&nbsp;
Being</B></FONT><br><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>Offered</B></FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom" COLSPAN="4" ALIGN="center" STYLE="border-bottom:1px solid #000000"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B># of Shares</B></FONT><br><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>held after</B></FONT><br><FONT
STYLE="font-family:Times New Roman" SIZE="1"><B>Offering(2)</B></FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom" COLSPAN="4" NOWRAP ALIGN="center" STYLE="border-bottom:1px solid #000000"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>Percentage</B></FONT><br><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>of
Shares</B></FONT><br><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>After&nbsp;Offering(2)</B></FONT></TD></TR>


<TR BGCOLOR="#cceeff">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Melinda Boyd</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">202,268</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">(3)</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">26,315</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">175,953</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">1.66</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">%</FONT></TD></TR>
<TR>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">M. Robert&nbsp;&amp; Phyllis Ching</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">1,788,696</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">(4)</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">263,157</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">1,525,539</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">7.93</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">%</FONT></TD></TR>
<TR BGCOLOR="#cceeff">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Virginia Drake</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">273,157</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">(5)</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">138,157</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">135,000</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">1.28</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">%</FONT></TD></TR>
<TR>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Fanelli Haag PLLC (6)</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">12,500</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">(7)</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">8,000</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">4,500</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">*</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD></TR>
<TR BGCOLOR="#cceeff">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Galloway Limited</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">727,233</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">(8)</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">727,233</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#151;&nbsp;&nbsp;</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#151;&nbsp;&nbsp;</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD></TR>
<TR>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Port Erin BioPharma Investments</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">105,263</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">(9)</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">105,263</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#151;&nbsp;&nbsp;</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#151;&nbsp;&nbsp;</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD></TR>
<TR BGCOLOR="#cceeff">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Regent Pacific Group Limited</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">328,947</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">(10)</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">328,947</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#151;&nbsp;&nbsp;</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#151;&nbsp;&nbsp;</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;</FONT></TD></TR>
</TABLE> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT STYLE="font-family:Times New Roman" SIZE="2">*Less than 1%. </FONT></P> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(1)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">If required, information about other selling security holders, except for any future transferees, pledgees, donees or successors of selling security holders named in
the table above, will be set forth in a prospectus supplement or amendment to the registration statement of which this prospectus is a part. Additionally, post-effective amendments to the registration statement will be filed to disclose any material
changes to the plan of distribution from the description contained in the final prospectus. </FONT></TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(2)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Assumes all shares offered by the Selling Stockholders hereby are sold and that the Selling Stockholders buy or sell no additional shares of Common Stock prior to the
completion of this offering. </FONT></TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(3)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Includes 118,370 shares and 67,409 shares issuable upon exercise of common stock purchase warrants. Also includes 16,489 shares of Common Stock issuable upon conversion
of Series A Preferred Stock, conversion of which is subject to stockholder approval, including additional shares of Series A Preferred Stock issuable in in-kind distribution as payment of dividends through March&nbsp;31, 2012.
</FONT></TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(4)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Includes 793,611 shares and 857,667 shares issuable upon the exercise of common stock purchase warrants of which 45,600 shares and 18,240 shares issuable upon the
exercise of common stock purchase warrants held by BBB Assets for which M. Robert Ching holds investment and voting control. Also includes 137,418 shares of Common Stock issuable upon conversion of Series A Preferred Stock, conversion of which is
subject to stockholder approval, including additional shares of Series A Preferred Stock issuable in in-kind distribution as payment of dividends through March&nbsp;31, 2012. Certain of the warrants and the conversion of the preferred stock are
subject to a contractual conversion blocker whereby the right to exercise or convert such warrant or preferred stock is limited such that Dr.&nbsp;and Mrs.&nbsp;Ching will not have greater than 9.99% beneficial ownership of outstanding Common Stock.
</FONT></TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(5)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Includes 253,157 shares and 20,000 shares issuable upon exercise of common stock purchase warrants. </FONT></TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(6)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Thomas Haag, partner at Fanelli Haag PLLC, is former Chief Counsel to the Company. Fanelli Haag currently serves as outside patent counsel to the Company and several of
its affiliates. </FONT></TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(7)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Includes 8,000 shares and 4,500 shares issuable upon the exercise of stock options. Dr.&nbsp;Haag and his partner, Dr.&nbsp;Fanelli share investment and voting power
with respect to the 8,000 shares. Dr.&nbsp;Haag has sole investment and voting power with respect to the shares issuable upon exercise of the stock options. </FONT></TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(8)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Denham Eke, Director, holds voting and investment control with respect to the shares owned by Galloway Limited. </FONT></TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(9)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Ross Jones holds voting and investment control with respect to the shares owned by Port Erin BioPharma Investments. </FONT></TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(10)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">James Mellon and Jamie Gibson, CEO, holds voting and investment control with respect to the shares owned by Regent Pacific Group Limited. </FONT></TD></TR></TABLE>
<P STYLE="font-size:24px;margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P>
 <p STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">4 </FONT></P>


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<h5 align="left"><a href="#toc">Table of Contents</a></h5>

 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B><A NAME="toc258445_7"></A>PLAN OF DISTRIBUTION </B></FONT></P>
<P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">The Shares offered by this prospectus may be sold by the Selling Stockholders. Such sales may be made at fixed prices that may be
changed, at market prices prevailing at the time of sale, at prices related to such prevailing market prices, or at negotiated prices, and may be made in the over-the-counter market or any exchange on which our common stock may then be listed, or
otherwise. In addition, the Selling Stockholders may sell some or all of their Shares through: </FONT></P> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="5%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">a block trade in which a broker-dealer may resell a portion of the block, as principal, in order to facilitate the transaction;
</FONT></P></TD></TR></TABLE> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="5%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">purchases by a broker-dealer, as principal, and resale by the broker-dealer for its account; </FONT></P></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="5%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">ordinary brokerage transactions and transactions in which a broker solicits purchasers; </FONT></P></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="5%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">in negotiated transactions; </FONT></P></TD></TR></TABLE> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="5%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">in a combination of any of the above methods of sale; or </FONT></P></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="5%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">any other method permitted under applicable law. </FONT></P></TD></TR></TABLE> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT
STYLE="font-family:Times New Roman" SIZE="2">The Selling Stockholders may also engage in short sales against the box, puts and calls and other hedging transactions in the Shares or derivatives of the Shares and may sell or deliver the Shares in
connection with these trades. For example, the Selling Stockholders may: </FONT></P> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="5%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">enter into transactions involving short sales of our common stock by broker-dealers; </FONT></P></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="5%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">sell our common stock short themselves and redeliver such shares to close out their short positions; </FONT></P></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="5%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">enter into option or other types of transactions that require the Selling Stockholder to deliver shares of common stock to a broker-dealer, who will
then resell or transfer the common stock under this prospectus; or </FONT></P></TD></TR></TABLE> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="5%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">loan or pledge shares of common stock to a broker-dealer, who may sell the loaned shares or, in the event of default, sell the pledged shares.
</FONT></P></TD></TR></TABLE> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="5%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">There is no assurance that any of the Selling Stockholders will sell any or all of the Shares offered by them. </FONT></P></TD></TR></TABLE>
<P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">The Selling Stockholders may negotiate and pay broker-dealers commissions, discounts or concessions for their services. Broker-dealers
engaged by the Selling Stockholders may allow other broker-dealers to participate in resales. However, the Selling Stockholders and any broker-dealers involved in the sale or resale of our common stock may qualify as &#147;underwriters&#148; within
the meaning of the Section&nbsp;2(a)(11) of the Securities Act. In addition, the broker-dealers&#146; commissions, discounts or concessions may qualify as underwriters&#146; compensation under the Securities Act. If the Selling Stockholders qualify
as &#147;underwriters,&#148; they will be subject to the prospectus delivery requirements of the Securities Act. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">In addition
to selling their shares of common stock under this prospectus, the Selling Stockholders may: </FONT></P> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="5%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">transfer their common stock in other ways not involving market makers or established trading markets, including, but not limited to, directly by gift,
distribution, privately negotiated transactions in compliance with applicable law or other transfer; or </FONT></P></TD></TR></TABLE> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="5%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">sell their common stock under Rule 144 of the Securities Act rather than under this prospectus, if the transaction meets the requirements of Rule 144.
Each Selling Stockholder will bear all expenses with respect to the offering of common stock by such Selling Stockholder. </FONT></P></TD></TR></TABLE> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT
STYLE="font-family:Times New Roman" SIZE="2">Under the applicable rules and regulations of the Exchange Act, any person engaged in the distribution of the Shares may not simultaneously engage in market making activities with respect to our common
stock for a period of </FONT></P>
 <p STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">5 </FONT></P>


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 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT STYLE="font-family:Times New Roman" SIZE="2">
two business days prior to the commencement of such distribution. In addition, each Selling Stockholder will be subject to the applicable provisions of the Exchange Act and the associated rules
and regulations under the Exchange Act, including Regulation M, which provisions may limit the timing of purchases and sales of shares of our common stock by the Selling Stockholders. </FONT></P>
<P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">The Selling Stockholders may from time to time pledge or grant a security interest in some or all of the Shares owned by them and, if
they default in the performance of their secured obligations, the pledges or secured parties may offer and sell the Shares from time to time under this prospectus after an amendment has been filed under Rule 424(b)(3) or other applicable provision
of the Securities Act of 1933 amending the list of Selling Stockholders to include the pledge, transferee or other successors in interest as selling stockholders under this prospectus. </FONT></P>
<P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">The Selling Stockholders also may transfer the Shares in other circumstances, in which case the respective pledgees, donees, transferees
or other successors in interest will be the selling beneficial owners for purposes of this prospectus and may sell the Shares from time to time under this prospectus after an amendment has been filed under Rule 424(b)(3) or other applicable
provision of the Securities Act amending the list of Selling Stockholders to include the pledge, transferee or other successors in interest as selling stockholders under this prospectus. </FONT></P>
<P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">We will make copies of this prospectus available to the Selling Stockholders and have informed them of the need to deliver copies of this
prospectus to purchasers at or prior to the time of any sale of the Shares. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">We will bear all costs, expenses and fees in
connection with the registration of the Shares. The Selling Stockholders will bear all commissions and discounts, if any, attributable to the resale of the Shares. The Selling Stockholders may agree to indemnify any broker-dealer or agent that
participates in transactions involving sales of the Shares against certain liabilities, including liabilities arising under the Securities Act. </FONT></P> <P STYLE="margin-top:24px;margin-bottom:0px" ALIGN="center"><FONT
STYLE="font-family:Times New Roman" SIZE="2"><B><A NAME="toc258445_8"></A>EXPERTS </B></FONT></P>  <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">The financial statements of the
Company incorporated in this prospectus by reference from the Company&#146;s Annual Report on Form 10-K for the year ended September&nbsp;30, 2011, have been audited by Rose, Snyder&nbsp;&amp; Jacobs, a corporation of Certified Public Accountants,
as stated in their report incorporated by reference, and given upon the authority of said firm as experts in auditing and accounting. </FONT></P>  <P STYLE="margin-top:24px;margin-bottom:0px" ALIGN="center"><FONT
STYLE="font-family:Times New Roman" SIZE="2"><B><A NAME="toc258445_9"></A>LEGAL MATTERS </B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">Certain legal matters, including
the validity of the securities offered pursuant to this registration statement, will be passed upon for us by Ropes&nbsp;&amp; Gray LLP, San Francisco, California. </FONT></P> <P STYLE="margin-top:24px;margin-bottom:0px" ALIGN="center"><FONT
STYLE="font-family:Times New Roman" SIZE="2"><B><A NAME="toc258445_10"></A>WHERE YOU CAN FIND MORE INFORMATION </B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">We must
comply with the informational requirements of the Securities Exchange Act of 1934, as amended, and we are required to file reports and proxy statements and other information with the Securities and Exchange Commission. You may read and copy these
reports, proxy statements and other information at the Public Reference Room maintained by the Securities and Exchange Commission at 100 F Street, N.E., Washington, D.C. 20549. You may also obtain copies at the prescribed rates from the Public
Reference Section of the Securities and Exchange Commission at its principal office in Washington, D.C. You may call the Securities and Exchange Commission at 1-800-SEC-0330 for further information about the public reference room. The Securities and
Exchange Commission also maintains a website that contains reports, proxy and information statements and other information regarding issuers like us that file electronically with the Securities and Exchange Commission. You may access the Securities
and Exchange Commission&#146;s web site at http://www.sec.gov. We maintain a website at www.arrowheadresearch.com. The information contained in, or that can be accessed through, our website is not incorporated by reference herein and is not part of
this prospectus. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">Statements contained in this prospectus as to the contents of any contract or other document are not
necessarily complete, and in each instance we refer you to the copy of the contract or document filed as an exhibit to the registration statement, each such statement being qualified in all respects by such reference. </FONT></P>
 <p STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">6 </FONT></P>


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 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B><A NAME="toc258445_11"></A>INCORPORATION OF CERTAIN INFORMATION BY REFERENCE
</B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">The Securities and Exchange Commission allows us to incorporate by reference in this prospectus the information that we
file with them. Incorporation by reference means that we can disclose important information to you by referring you to other documents that are legally considered to be part of this prospectus. Later information that we file with the Securities and
Exchange Commission will automatically update and supersede the information in this prospectus, any supplement and the documents listed below. Our SEC file number is 0-21898. We incorporate by reference the specific documents listed below and any
future filings made with the Securities and Exchange Commission under Section&nbsp;13(a), 13(c), 14, or 15(d) of the Securities Exchange Act of 1934, as amended, until all of the shares of common stock and warrant shares covered by this prospectus
are sold: </FONT></P> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="5%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">The Company&#146;s Annual Report on Form 10-K for the fiscal year ended September&nbsp;30, 2011, filed on December&nbsp;20, 2011;
</FONT></P></TD></TR></TABLE> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="5%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">The Company&#146;s Current Reports on Form 8-K filed on October&nbsp;6, 2011,&nbsp;October 24, 2011 (as amended by the Company&#146;s Current Report on
Form 8-K/A filed on December 30, 2011), October&nbsp;26, 2011,&nbsp;October&nbsp;27, 2011,&nbsp;November&nbsp;15, 2011 and November&nbsp;17, 2011; </FONT></P></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="5%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">The description of the Company&#146;s common stock contained in its registration statement on Form 8-A/A (Registration No. 000-21898), filed on
November&nbsp;1, 2010, including any amendments or reports filed for the purpose of updating such description; and </FONT></P></TD></TR></TABLE> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="5%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">&#149;</FONT></TD>
<TD WIDTH="1%" VALIGN="top"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">All documents filed by the Company pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act, after the date of the original Registration
Statement and prior to effectiveness of the registration statement of which this prospectus is a part, provided that all documents &#147;furnished&#148; by the Company to the SEC and not &#147;filed&#148; are not deemed incorporated by reference
herein. </FONT></P></TD></TR></TABLE> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">We will furnish without charge to each person, including any beneficial owner, to whom this
prospectus is delivered, upon written or oral request, a copy of any document incorporated by reference. Requests should be addressed to Corporate Secretary, 225&nbsp;South Lake Street, Suite 300, Pasadena, CA 91101 or may be made telephonically at
(626)&nbsp;304-3400. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">You should rely only on the information incorporated by reference or provided in this prospectus or any
prospectus supplement. We have not authorized anyone to provide you with different information. You should not assume that the information contained in this prospectus or the accompanying prospectus supplement is accurate on any date subsequent to
the date set forth on the front of the document or that any information we have incorporated by reference is correct on any date subsequent to the date of the document incorporated by reference, even though this prospectus and any accompanying
prospectus supplement is delivered or securities are sold on a later date. </FONT></P>
 <p STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">7 </FONT></P>


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<h5 align="left"><a href="#toc">Table of Contents</a></h5>

 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>PART II </B></FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT
STYLE="font-family:Times New Roman" SIZE="2"><B>INFORMATION NOT REQUIRED IN PROSPECTUS </B></FONT></P> <P STYLE="margin-top:18px;margin-bottom:0px"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>Item&nbsp;14. Other Expenses of Issuance and
Distribution (1). </B></FONT></P> <P STYLE="margin-top:6px;margin-bottom:0px"><FONT STYLE="font-family:Times New Roman" SIZE="2">The following are the estimated expenses of the distribution of the shares registered hereunder on Form&nbsp;S-3:
</FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE" ALIGN="center">


<TR>
<TD WIDTH="93%"></TD>
<TD VALIGN="bottom" WIDTH="2%"></TD>
<TD></TD>
<TD></TD>
<TD></TD></TR>


<TR BGCOLOR="#cceeff">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Registration Fee&#151;Securities and Exchange Commission</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">$</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2"> 1,103</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;</FONT></TD></TR>
<TR>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Accountants Fees and Expenses</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">$</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">10,000</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;</FONT></TD></TR>
<TR BGCOLOR="#cceeff">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Legal Fees and Expenses</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">$</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">10,000</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;</FONT></TD></TR>
<TR>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Miscellaneous</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">$</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">10,000</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;</FONT></TD></TR>
<TR STYLE="font-size:1px">
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE="border-top:1px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom"> <P STYLE="border-top:1px solid #000000">&nbsp;</P></TD>
<TD>&nbsp;</TD></TR>
<TR BGCOLOR="#cceeff">
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Total</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">$</FONT></TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2">31,103</FONT></TD>
<TD NOWRAP VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;</FONT></TD></TR>
<TR STYLE="font-size:1px">
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE="border-top:1px solid #000000">&nbsp;</P></TD>
<TD VALIGN="bottom"> <P STYLE="border-top:1px solid #000000">&nbsp;</P></TD>
<TD>&nbsp;</TD></TR>
</TABLE>  <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(1)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">The amounts set forth below, except for the SEC Registration Fee, are estimated. </FONT></TD></TR></TABLE> <P STYLE="margin-top:18px;margin-bottom:0px"><FONT
STYLE="font-family:Times New Roman" SIZE="2"><B>Item&nbsp;15. Indemnification of Directors and Officers. </B></FONT></P> <P STYLE="margin-top:6px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">The
Company&#146;s Certificate of Incorporation provides for the elimination of personal monetary liability of directors to the fullest extent permissible under Delaware law. Delaware law does not permit the elimination or limitation of director
monetary liability for: (i)&nbsp;breaches of the director&#146;s duty of loyalty to the corporation or its stockholders; (ii)&nbsp;acts or omissions not in good faith or involving intentional misconduct or knowing violations of law; (iii)&nbsp;the
payment of unlawful dividends or unlawful stock repurchases or redemptions or (iv)&nbsp;transactions in which the director received an improper personal benefit. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT
STYLE="font-family:Times New Roman" SIZE="2">Section&nbsp;145 of the Delaware General Corporation Law permits a Delaware corporation to indemnify, on certain terms and conditions, any person who was or is a party or is threatened to be made a party
to any threatened pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative, by reason of the fact that he is or was a director, officer, employee or agent of the corporation or is or was serving at
the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise against expenses (including attorneys&#146; fees), judgments, fines and amounts paid in settlement
actually and reasonably incurred by him in connection with such action. The Certificate of Incorporation and Bylaws of the Company require the Company to indemnify the Company&#146;s directors and officers to the fullest extent permitted under
Delaware law. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors,
officers and controlling persons of the Company pursuant to the foregoing provisions, the Company has been advised that in the opinion of the SEC such indemnification is against public policy as expressed in the Securities Act and is, therefore,
unenforceable. </FONT></P>
 <p STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">II-1
</FONT></P>


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<h5 align="left"><a href="#toc">Table of Contents</a></h5>

 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>Item&nbsp;16. Exhibit Index. </B></FONT></P>
<P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE" ALIGN="center">


<TR>
<TD></TD>
<TD VALIGN="bottom" WIDTH="5%"></TD>
<TD WIDTH="92%"></TD></TR>
<TR>
<TD VALIGN="bottom" NOWRAP ALIGN="center"> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>Exhibit</B></FONT></P>
<P STYLE="margin-top:0px;margin-bottom:1px;border-bottom:1px solid #000000;width:25pt" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>No.</B></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"> <P STYLE="border-bottom:1px solid #000000;width:39pt"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>Description</B></FONT></P></TD></TR>


<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;4.1</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Form of Common Stock Certificate (1)</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;5.1</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Opinion of Ropes &amp; Gray LLP (2) </FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP><FONT STYLE="font-family:Times New Roman" SIZE="2">23.1</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Consent of Rose, Snyder &amp; Jacobs, the registrant&#146;s independent registered public accounting firm**</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP><FONT STYLE="font-family:Times New Roman" SIZE="2">23.2</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Consent of Ropes &amp; Gray LLP (included in legal opinion filed as Exhibit 5.1) (2)</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP><FONT STYLE="font-family:Times New Roman" SIZE="2">24.1</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Power of Attorney (included on signature page) (2)</FONT></TD></TR>
</TABLE>  <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">**</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Filed herewith. </FONT></TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(1)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Incorporated by reference from Amendment No.&nbsp;2 to the Registration Statement on Form S-1, filed by the registrant on September&nbsp;11, 2009.
</FONT></TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(2)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Incorporated by reference from the Registration Statement on Form S-3 (File No. 333-178073), filed by the registrant on November 21, 2011. </FONT></TD></TR></TABLE>
 <P STYLE="margin-top:18px;margin-bottom:0px"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>Item&nbsp;17. Undertakings. </B></FONT></P>
<P STYLE="margin-top:6px;margin-bottom:0px"><FONT STYLE="font-family:Times New Roman" SIZE="2"><I>Item&nbsp;512(a) of Regulation S-K</I>. The undersigned registrant hereby undertakes: </FONT></P>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(1)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement: </FONT></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(i)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">To include any prospectus required by Section&nbsp;10(a)(3) of the Securities Act of 1933; </FONT></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(ii)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof)
which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of
securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) if, in the
aggregate, the changes in volume and price represent no more than 20 percent change in the maximum aggregate offering price set forth in the &#147;Calculation of Registration Fee&#148; table in the effective registration statement; and
</FONT></TD></TR></TABLE> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(iii)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such
information in the registration statement; </FONT></TD></TR></TABLE> <P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2"><I>Provided, however</I>, That: </FONT></P>
<P STYLE="margin-top:12px;margin-bottom:0px; margin-left:4%; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">Paragraphs (a)(1)(i), (a)(1)(ii) and (a)(1)(iii) of this section do not apply if the information required to be included
in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the Commission by the registrant pursuant to Section&nbsp;13 or Section&nbsp;15(d) of the Securities Exchange Act of 1934 that are incorporated by
reference in the registration statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement. </FONT></P> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(2)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration
statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial <I>bona fide</I> offering thereof. </FONT></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(3)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.
</FONT></TD></TR></TABLE> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(4)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">That, for the purpose of determining liability under the Securities Act of 1933 to any purchaser: </FONT></TD></TR></TABLE>
 <p STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">II-2
</FONT></P>


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<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(A)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Each prospectus filed by the registrant pursuant to Rule 424(b)(3) shall be deemed to be part of the registration statement as of the date the filed prospectus was
deemed part of and included in this registration statement; and </FONT></TD></TR></TABLE> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(B)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Each prospectus required to be filed pursuant to Rule 424(b)(2), (b)(5), or (b)(7) as part of a registration statement in reliance on Rule 430B relating to an offering
made pursuant to Rule 415(a)(1)(i), (vii), or (x)&nbsp;for the purpose of providing the information required by Section&nbsp;10(a) of the Securities Act of 1933 shall be deemed to be part of and included in the registration statement as of the
earlier of the date such form of prospectus is first used after effectiveness or the date of the first contract of sale of securities in the offering described in the prospectus. As provided in Rule 430B, for liability purposes of the issuer and any
person that is at that date an underwriter, such date shall be deemed to be a new effective date of the registration statement relating to the securities in the registration statement to which that prospectus relates, and the offering of such
securities at that time shall be deemed to be the initial <I>bona fide</I> offering thereof. <I>Provided, however</I>, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document
incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such effective date, supersede or modify any
statement that was made in the registration statement or prospectus that was part of this Registration Statement or made in any such document immediately prior to such effective date. </FONT></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(5)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">That, for the purpose of determining liability of the registrant under the Securities Act of 1933 to any purchaser in the initial distribution of the securities:
</FONT></TD></TR></TABLE> <P STYLE="margin-top:6px;margin-bottom:0px; margin-left:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">The undersigned registrant undertakes that in a primary offering of securities of the undersigned registrant
pursuant to this registration statement, regardless of the underwriting method used to sell the securities to the purchaser, if the securities are offered or sold to such purchaser by means of any of the following communications, the undersigned
registrant will be a seller to the purchaser and will be considered to offer or sell such securities to such purchaser: </FONT></P> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(i)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Any preliminary prospectus or prospectus of the undersigned registrant relating to the offering required to be filed pursuant to Rule 424; </FONT></TD></TR></TABLE>
<P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(ii)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Any free writing prospectus relating to the offering prepared by or on behalf of the undersigned registrant or used or referred to by the undersigned registrant;
</FONT></TD></TR></TABLE> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(iii)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">The portion of any other free writing prospectus relating to the offering containing material information about the undersigned registrant or its securities provided by
or on behalf of the undersigned registrant; and </FONT></TD></TR></TABLE> <P STYLE="font-size:6px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(iv)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Any other communication that is an offer in the offering made by the undersigned registrant to the purchaser. </FONT></TD></TR></TABLE>
<P STYLE="margin-top:12px;margin-bottom:0px"><FONT STYLE="font-family:Times New Roman" SIZE="2"><I>Item&nbsp;512(b) of Regulation S-K</I>. The undersigned registrant hereby undertakes that, for purposes of determining any liability under the
Securities Act of 1933, each filing of the registrant&#146;s annual report pursuant to Section&nbsp;13(a) or Section&nbsp;15(d) of the Securities Exchange Act of 1934, as amended (and, where applicable, each filing of an employee benefit plan&#146;s
annual report pursuant to Section&nbsp;15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and
the offering of such securities at that time shall be deemed to be the initial <I>bona fide</I> offering thereof. </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT STYLE="font-family:Times New Roman" SIZE="2"><I>Item&nbsp;512(h) of
Regulation S-K</I>. Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the
registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Act, and is, therefore, unenforceable. In the event that a claim for indemnification against
such liabilities (other than the payment by the registrant of expenses incurred or </FONT></P>
 <p STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">II-3
</FONT></P>


<p Style='page-break-before:always'>
<HR  SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">
<h5 align="left"><a href="#toc">Table of Contents</a></h5>

 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT STYLE="font-family:Times New Roman" SIZE="2">
paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification
by it is against public policy as expressed in the Act and will be governed by the final adjudication of such issue. </FONT></P>
 <p STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">II-4
</FONT></P>


<p Style='page-break-before:always'>
<HR  SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">
<h5 align="left"><a href="#toc">Table of Contents</a></h5>

 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>SIGNATURES </B></FONT></P>
<P STYLE="margin-top:12px;margin-bottom:0px; text-indent:4%"><FONT STYLE="font-family:Times New Roman" SIZE="2">Pursuant to the requirements of the Securities Act of 1933, the registrant certifies that it has reasonable grounds to believe that it
meets all of the requirements for filing on Form&nbsp;S-3 and has duly caused this Amendment No. 1 to registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the city of Pasadena, state of California, on
January 9, 2012. </FONT></P>  <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>  <DIV ALIGN="right">
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="40%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE">


<TR>
<TD WIDTH="6%"></TD>
<TD VALIGN="bottom" WIDTH="2%"></TD>
<TD WIDTH="92%"></TD></TR>


<TR>
<TD VALIGN="top" COLSPAN="3"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>ARROWHEAD RESEARCH CORPORATION</B></FONT></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">By:</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;/s/&nbsp;&nbsp;Kenneth A.
Myszkowski&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Kenneth A. Myszkowski</FONT></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Chief Financial Officer</FONT></TD></TR>
</TABLE></DIV>    <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE">


<TR>
<TD WIDTH="37%"></TD>
<TD VALIGN="bottom" WIDTH="2%"></TD>
<TD WIDTH="44%"></TD>
<TD VALIGN="bottom" WIDTH="2%"></TD>
<TD WIDTH="15%"></TD></TR>
<TR>
<TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="border-bottom:1px solid #000000"> <P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>Signature</B></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="center" STYLE="border-bottom:1px solid #000000"> <P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>Title</B></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom" ALIGN="center" STYLE="border-bottom:1px solid #000000"> <P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>Date</B></FONT></P></TD></TR>


<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top"> <P STYLE="margin-top:0px;margin-bottom:0px;border-bottom:1px solid #000000" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">/s/ Christopher Anzalone</FONT></P>
<P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">Christopher Anzalone</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"> <P STYLE="margin-top:0px;margin-bottom:0px; margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Chief Executive Officer and President and</FONT></P>
<P STYLE="margin-top:0px;margin-bottom:1px; margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Director (Principal Executive Officer)</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" NOWRAP ALIGN="center"> <P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">January 9, 2012</FONT></P></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top"> <P STYLE="margin-top:0px;margin-bottom:0px;border-bottom:1px solid #000000" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">*</FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT
STYLE="font-family:Times New Roman" SIZE="2">R. Bruce Stewart</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Executive Chairman of the Board</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" NOWRAP ALIGN="center"> <P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">January 9, 2012</FONT></P></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top"> <P STYLE="margin-top:0px;margin-bottom:0px;border-bottom:1px solid #000000" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">/s/ Kenneth A. Myszkowski</FONT></P>
<P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">Kenneth A. Myszkowski</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"> <P STYLE="margin-top:0px;margin-bottom:0px; margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Chief Financial Officer</FONT></P>
<P STYLE="margin-top:0px;margin-bottom:0px; margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">(Principal Financial Officer and Principal</FONT></P>
<P STYLE="margin-top:0px;margin-bottom:1px; margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Accounting Officer)</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" NOWRAP ALIGN="center"> <P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">January 9, 2012</FONT></P></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top"> <P STYLE="margin-top:0px;margin-bottom:0px;border-bottom:1px solid #000000" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">*</FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT
STYLE="font-family:Times New Roman" SIZE="2">Edward W. Frykman</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Director</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" NOWRAP ALIGN="center"> <P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">January 9, 2012</FONT></P></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top"> <P STYLE="margin-top:0px;margin-bottom:0px;border-bottom:1px solid #000000" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">*</FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT
STYLE="font-family:Times New Roman" SIZE="2">Charles P. McKenney</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Director</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" NOWRAP ALIGN="center"> <P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">January 9, 2012</FONT></P></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top"> <P STYLE="margin-bottom:0px;margin-top:0px;border-bottom:1px solid #000000" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">*</FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT
STYLE="font-family:Times New Roman" SIZE="2">Mauro Ferrari</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Director</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" NOWRAP ALIGN="center"> <P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">January 9, 2012</FONT></P></TD></TR>
<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top"> <P STYLE="margin-bottom:0px;margin-top:0px;border-bottom:1px solid #000000" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">*</FONT></P> <P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT
STYLE="font-family:Times New Roman" SIZE="2">Douglass Given</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"> <P STYLE="margin-left:1.00em; text-indent:-1.00em"><FONT STYLE="font-family:Times New Roman" SIZE="2">Director</FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" NOWRAP ALIGN="center"> <P STYLE="margin-top:0px;margin-bottom:1px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">January 9, 2012</FONT></P></TD></TR>
</TABLE>  <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="40%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE">


<TR>
<TD WIDTH="8%"></TD>
<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="91%"></TD></TR>


<TR>
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">*By</FONT></TD>
<TD VALIGN="bottom" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="top" STYLE="BORDER-BOTTOM:1px solid #000000"><FONT STYLE="font-family:Times New Roman" SIZE="2">/s/ Kenneth A. Myszkowski</FONT></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">Kenneth A. Myszkowski</FONT></TD></TR>
<TR>
<TD VALIGN="top"></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;</FONT></TD>
<TD VALIGN="bottom"><FONT STYLE="font-family:Times New Roman" SIZE="2">Attorney in Fact</FONT></TD></TR>
</TABLE>
 <p STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">II-5
</FONT></P>


<p Style='page-break-before:always'>
<HR  SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">
<h5 align="left"><a href="#toc">Table of Contents</a></h5>

 <P STYLE="margin-top:0px;margin-bottom:0px"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>EXHIBIT INDEX. </B></FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE" ALIGN="center">


<TR>
<TD></TD>
<TD VALIGN="bottom" WIDTH="5%"></TD>
<TD WIDTH="92%"></TD></TR>
<TR>
<TD VALIGN="bottom" NOWRAP ALIGN="center"> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>Exhibit</B></FONT></P>
<P STYLE="margin-top:0px;margin-bottom:1px;border-bottom:1px solid #000000;width:25pt" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>No.</B></FONT></P></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="bottom"> <P STYLE="border-bottom:1px solid #000000;width:39pt"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>Description</B></FONT></P></TD></TR>


<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;4.1</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Form of Common Stock Certificate (1)</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP><FONT STYLE="font-family:Times New Roman" SIZE="2">&nbsp;&nbsp;5.1</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Opinion of Ropes &amp; Gray LLP (2)</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP><FONT STYLE="font-family:Times New Roman" SIZE="2">23.1</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Consent of Rose, Snyder &amp; Jacobs, the registrant&#146;s independent registered public accounting firm**</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP><FONT STYLE="font-family:Times New Roman" SIZE="2">23.2</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Consent of Ropes &amp; Gray LLP (included in legal opinion filed as Exhibit 5.1) (2)</FONT></TD></TR>
<TR>
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR>
<TD VALIGN="top" NOWRAP><FONT STYLE="font-family:Times New Roman" SIZE="2">24.1</FONT></TD>
<TD VALIGN="bottom"><FONT SIZE="1">&nbsp;&nbsp;</FONT></TD>
<TD VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Power of Attorney (included on signature page) (2)</FONT></TD></TR>
</TABLE>  <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">**</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Filed herewith. </FONT></TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(1)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Incorporated by reference from Amendment No.&nbsp;2 to the Registration Statement on Form S-1, filed by the registrant on September&nbsp;11, 2009.
</FONT></TD></TR></TABLE>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>
<TD WIDTH="4%" VALIGN="top" ALIGN="left"><FONT STYLE="font-family:Times New Roman" SIZE="2">(2)</FONT></TD>
<TD ALIGN="left" VALIGN="top"><FONT STYLE="font-family:Times New Roman" SIZE="2">Incorporated by reference from the Registration Statement on Form S-3 (File No. 333-178073), filed by the registrant on November 21, 2011. </FONT></TD></TR></TABLE>

 <p STYLE="margin-top:0px;margin-bottom:0px"><FONT SIZE="1">&nbsp;</FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2">II-6
</FONT></P>

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<TYPE>EX-23.1
<SEQUENCE>2
<FILENAME>d258445dex231.htm
<DESCRIPTION>CONSENT  OF ROSE, SNYDER & JACOBS
<TEXT>
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 <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="right"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>E<SMALL>XHIBIT</SMALL> 23.1 </B></FONT></P>
<P STYLE="margin-top:12px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM </B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT
STYLE="font-family:Times New Roman" SIZE="2">We hereby consent to the incorporation by reference, in this Registration Statement on Amendment #1 to Form S-3 of our report dated December 20, 2011, with respect to the consolidated financial statements
of Arrowhead Research Corporation and Subsidiaries appearing in the Company&#146;s Annual Report on Form 10-K for the year ended September 30, 2011, and to the reference of our Firm under the caption &#147;Experts&#148; in the Registration
Statement. </FONT></P> <P STYLE="margin-top:18px;margin-bottom:0px"><FONT STYLE="font-family:Times New Roman" SIZE="2">/s/ Rose, Snyder&nbsp;&amp; Jacobs </FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT
STYLE="font-family:Times New Roman" SIZE="2">Rose, Snyder&nbsp;&amp; Jacobs </FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT STYLE="font-family:Times New Roman" SIZE="2">A Corporation of Certified Public Accountants </FONT></P>
<P STYLE="margin-top:12px;margin-bottom:0px"><FONT STYLE="font-family:Times New Roman" SIZE="2">Encino, California </FONT></P> <P STYLE="margin-top:0px;margin-bottom:0px"><FONT STYLE="font-family:Times New Roman" SIZE="2">January 6, 2012 </FONT></P>

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