<SEC-DOCUMENT>0001144204-18-025766.txt : 20180507
<SEC-HEADER>0001144204-18-025766.hdr.sgml : 20180507
<ACCEPTANCE-DATETIME>20180507172030
ACCESSION NUMBER:		0001144204-18-025766
CONFORMED SUBMISSION TYPE:	8-K
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20180507
ITEM INFORMATION:		Entry into a Material Definitive Agreement
ITEM INFORMATION:		Financial Statements and Exhibits
FILED AS OF DATE:		20180507
DATE AS OF CHANGE:		20180507

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Synthetic Biologics, Inc.
		CENTRAL INDEX KEY:			0000894158
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				133808303
		STATE OF INCORPORATION:			NV
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		8-K
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-12584
		FILM NUMBER:		18812227

	BUSINESS ADDRESS:	
		STREET 1:		617 DETROIT STREET, SUITE 100
		CITY:			ANN ARBOR
		STATE:			MI
		ZIP:			48104
		BUSINESS PHONE:		(734) 332-7800

	MAIL ADDRESS:	
		STREET 1:		9605 MEDICAL CENTER DRIVE
		STREET 2:		SUITE 270
		CITY:			ROCKVILLE
		STATE:			MD
		ZIP:			20850

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ADEONA PHARMACEUTICALS, INC.
		DATE OF NAME CHANGE:	20081027

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	PIPEX PHARMACEUTICALS, INC.
		DATE OF NAME CHANGE:	20061214

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	SHEFFIELD PHARMACEUTICALS INC
		DATE OF NAME CHANGE:	19970730
</SEC-HEADER>
<DOCUMENT>
<TYPE>8-K
<SEQUENCE>1
<FILENAME>tv493213_8k.htm
<DESCRIPTION>8-K
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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center"><B>SECURITIES AND EXCHANGE COMMISSION</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center"><B>Washington, D.C. 20549</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center"><B>FORM 8-K</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center"><B>CURRENT REPORT</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center"><B>Pursuant to Section 13 or 15(d)</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center"><B>of the Securities Exchange Act of 1934</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center">Date of Report (Date of earliest event reported):
May 7, 2018</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center"><FONT STYLE="font-size: 14pt"><B>SYNTHETIC
BIOLOGICS, INC.</B></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center">(Exact name of registrant as specified in
its charter)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font: 10pt Times New Roman, Times, Serif; border-collapse: collapse">
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    <TD STYLE="width: 33%; border-bottom: black 1pt solid; padding-right: 0.8pt; text-align: center"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Nevada</FONT></TD>
    <TD STYLE="width: 1%; padding-right: 0.8pt; text-align: center">&nbsp;</TD>
    <TD STYLE="width: 32%; border-bottom: black 1pt solid; padding-right: 0.8pt; text-align: center"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">001-12584</FONT></TD>
    <TD STYLE="width: 1%; padding-right: 0.8pt; text-align: center">&nbsp;</TD>
    <TD STYLE="width: 33%; border-bottom: black 1pt solid; padding-right: 0.8pt; text-align: center"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">13-3808303</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.8pt; text-align: center"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">(State or other jurisdiction of incorporation)</FONT></TD>
    <TD STYLE="padding-right: 0.8pt; text-align: center">&nbsp;</TD>
    <TD STYLE="padding-right: 0.8pt; text-align: center"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">(Commission File No.)</FONT></TD>
    <TD STYLE="padding-right: 0.8pt; text-align: center">&nbsp;</TD>
    <TD STYLE="padding-right: 0.8pt; text-align: center"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">(IRS Employer Identification No.)</FONT></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center">9605 Medical Center Drive, Suite 270</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center">Rockville, MD 20850</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center">(Address of principal executive offices
and zip code)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center">&nbsp;&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center">Registrant&rsquo;s telephone number, including
area code: (301) 417-4364</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center">N/A&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center">(Former name or former address, if changed
since last report)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">Check the appropriate
box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the
following provisions:</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font: 10pt Times New Roman, Times, Serif; border-collapse: collapse">
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    <TD STYLE="width: 6%; text-align: justify">&nbsp;</TD>
    <TD STYLE="width: 3%; padding-right: 0.8pt"><FONT STYLE="font-family: Wingdings; font-size: 10pt">&uml;</FONT></TD>
    <TD STYLE="width: 91%; padding-right: 0.8pt; text-align: justify"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)</FONT></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.85in; text-indent: -25.15pt">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font: 10pt Times New Roman, Times, Serif; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 6%; text-align: justify">&nbsp;</TD>
    <TD STYLE="width: 3%; padding-right: 0.8pt"><FONT STYLE="font-family: Wingdings; font-size: 10pt">&uml;</FONT></TD>
    <TD STYLE="width: 91%; padding-right: 0.8pt; text-align: justify"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)</FONT></TD></TR>
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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.85in; text-indent: -25.15pt">&nbsp;</P>

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<TR STYLE="vertical-align: top">
    <TD STYLE="width: 6%; text-align: justify">&nbsp;</TD>
    <TD STYLE="width: 3%; padding-right: 0.8pt"><FONT STYLE="font-family: Wingdings; font-size: 10pt">&uml;</FONT></TD>
    <TD STYLE="width: 91%; padding-right: 0.8pt; text-align: justify"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))</FONT></TD></TR>
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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.85in; text-indent: -25.15pt">&nbsp;</P>

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<TR STYLE="vertical-align: top">
    <TD STYLE="width: 6%; text-align: justify">&nbsp;</TD>
    <TD STYLE="width: 3%; padding-right: 0.8pt"><FONT STYLE="font-family: Wingdings; font-size: 10pt">&uml;</FONT></TD>
    <TD STYLE="width: 91%; padding-right: 0.8pt; text-align: justify"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))</FONT></TD></TR>
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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Indicate by check mark whether the registrant
is an emerging growth company as defined in in Rule 405 of the Securities Act of 1933 (&sect;230.405 of this chapter) or Rule 12b-2
of the Securities Exchange Act of 1934 (&sect;240.12b-2 of this chapter).</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: right"><FONT STYLE="font-family: Times New Roman, Times, Serif">Emerging
growth company </FONT><FONT STYLE="font-family: Wingdings">&uml;</FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"><FONT STYLE="font-family: Times New Roman, Times, Serif">If
an emerging growth company, indicate by checkmark if the registrant has elected not to use the extended transition period for complying
with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. &nbsp; </FONT><FONT STYLE="font-family: Wingdings">&uml;</FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>



<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;&nbsp;</P>


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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Item 1.01 Entry into a Material Definitive Agreement.</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">On May 7, 2018, Synthetic Biologics, Inc.
(the &ldquo;Company&rdquo;) entered into amendment no. 1 (the &ldquo;Amendment&rdquo;) to its existing At Market Issuance Sales
Agreement that it entered into with B. Riley FBR, Inc. on August 5, 2016 (the &ldquo;Sales Agreement&rdquo; and, as amended by
the Amendment, the &ldquo;Amended Sales Agreement&rdquo;). The sole effect of the Amendment is to allow for the sale of the shares
of the Company&rsquo;s common stock under the Amended Sales Agreement to be sold pursuant to a new registration statement on Form
S-3 to be filed by the Company.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">A copy of the Amendment is attached as
Exhibit 1.1 hereto and is incorporated herein by reference. A copy of the Sales Agreement is attached as Exhibit 1.2 hereto and
is incorporated herein by reference. The foregoing description of the material terms of the Amended Sales Agreement, consisting
of the Amendment and the Sales Agreement, does not purport to be complete and is qualified in its entirety by reference to such
exhibits.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><FONT STYLE="font: 10pt Times New Roman, Times, Serif"><B>Item 9.01 Financial Statements and Exhibits.</B></FONT></P>



<P STYLE="margin: 0"></P>

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    <TD STYLE="width: 3%; padding: 0; text-indent: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="width: 97%; padding: 0; text-indent: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding: 0; text-indent: 0"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">(d)</FONT></TD>
    <TD STYLE="padding: 0; text-indent: 0"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Exhibits</FONT></TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding: 0; text-indent: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="padding: 0; text-indent: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding: 0; text-indent: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="padding: 0; text-indent: 0"><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><FONT STYLE="font-size: 10pt"><A HREF="tv493213_ex1-1.htm">1.1
        Amendment No. 1 to At-The-Market Issuance Sales Agreement dated May 7, 2018 between Synthetic Biologics, Inc. and B. Riley
        FBR, Inc.&nbsp;</A></FONT></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P></TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding: 0; text-indent: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="padding: 0; text-indent: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding: 0; text-indent: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="padding: 0; text-indent: 0"><A HREF="http://www.sec.gov/Archives/edgar/data/894158/000114420416116716/v446112_ex1-1.htm" STYLE="-sec-extract: exhibit"><FONT STYLE="font-size: 10pt">1.2 At-the-Market Issuance Sales Agreement dated August
    5, 2016 between Synthetic Biologics, Inc. and FBR Capital Markets &amp; Co. (Incorporated by reference to 1.1 of the Registrant&rsquo;s
    Current Report on Form 8-K filed August 5, 2016 (File No. 001-12584).</FONT></A></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>


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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center"><B>SIGNATURES</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Pursuant to the requirements of the Securities
Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font: 10pt Times New Roman, Times, Serif; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.8pt"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Dated:&nbsp;&nbsp;May 7, 2018</FONT></TD>
    <TD COLSPAN="2" STYLE="padding-right: 1.8pt"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">SYNTHETIC BIOLOGICS, INC.</FONT></TD>
    <TD STYLE="padding-right: 0.8pt">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 52%; padding-right: 0.8pt">&nbsp;</TD>
    <TD STYLE="width: 4%; padding-right: 0.8pt">&nbsp;</TD>
    <TD STYLE="width: 29%; padding-right: 0.8pt">&nbsp;</TD>
    <TD STYLE="width: 15%; padding-right: 0.8pt">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.8pt">&nbsp;</TD>
    <TD STYLE="padding-right: 0.8pt">&nbsp;</TD>
    <TD STYLE="padding-right: 0.8pt">&nbsp;</TD>
    <TD STYLE="padding-right: 0.8pt">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.8pt">&nbsp;</TD>
    <TD STYLE="padding-right: 0.8pt"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">By:</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding-right: 0.8pt"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">/s/ Steven A. Shallcross</FONT></TD>
    <TD STYLE="padding-right: 0.8pt">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.8pt">&nbsp;</TD>
    <TD STYLE="padding-right: 0.8pt">&nbsp;</TD>
    <TD STYLE="padding-right: 0.8pt"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Name: Steven A. Shallcross</FONT></TD>
    <TD STYLE="padding-right: 0.8pt">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.8pt">&nbsp;</TD>
    <TD STYLE="padding-right: 0.8pt">&nbsp;</TD>
    <TD>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0.8pt 0pt 0">Title: Interim Chief Executive Officer and</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0.8pt 0pt 0">Chief Financial Officer</P></TD>
    <TD STYLE="padding-right: 0.8pt">&nbsp;</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>


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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center"><B>EXHIBIT INDEX</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font: 10pt Times New Roman, Times, Serif; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2" STYLE="border-bottom: black 1pt solid; padding: 0; text-indent: 0"><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0.8pt 0pt 0; text-align: center"><FONT STYLE="font-size: 10pt"><B>Exhibit</B></FONT></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0.8pt 0pt 0; text-align: center"><FONT STYLE="font-size: 10pt"><B>Number</B></FONT></P></TD>
    <TD STYLE="padding: 0; text-indent: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid; padding: 0; text-indent: 0"><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0.8pt 0pt 0"><FONT STYLE="font-size: 10pt"><B>&nbsp;</B></FONT></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0.8pt 0pt 0"><FONT STYLE="font-size: 10pt"><B>Description</B></FONT></P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2" STYLE="padding: 0; text-align: center; text-indent: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="padding: 0; text-indent: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="padding: 0; text-align: justify; text-indent: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding: 0; text-indent: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD COLSPAN="3" STYLE="padding: 0; text-indent: 0"><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><FONT STYLE="font-size: 10pt"><A HREF="tv493213_ex1-1.htm">1.1
        Amendment No. 1 to At-The-Market Issuance Sales Agreement dated May 7, 2018 between Synthetic Biologics, Inc. and B. Riley
        FBR, Inc.</A></FONT></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P></TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD STYLE="padding: 0; text-indent: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD COLSPAN="3" STYLE="padding: 0; text-indent: 0"><A HREF="http://www.sec.gov/Archives/edgar/data/894158/000114420416116716/v446112_ex1-1.htm" STYLE="-sec-extract: exhibit"><FONT STYLE="font-size: 10pt">1.2 At-the-Market Issuance Sales Agreement
    dated August 5, 2016 between Synthetic Biologics, Inc. and FBR Capital Markets &amp; Co. (Incorporated by reference to 1.1
    of the Registrant&rsquo;s Current Report on Form 8-K filed August 5, 2016 (File No. 001-12584).</FONT></A></TD></TR>
<TR>
    <TD STYLE="width: 1%; padding: 0; text-indent: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="width: 13%; padding: 0; text-indent: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="width: 5%; padding: 0; text-indent: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="width: 81%; padding: 0; text-indent: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD></TR>
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<TYPE>EX-1.1
<SEQUENCE>2
<FILENAME>tv493213_ex1-1.htm
<DESCRIPTION>EXHIBIT 1.1
<TEXT>
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<HEAD>
     <TITLE></TITLE>
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<P STYLE="margin: 0; text-align: right"><B>Exhibit 1.1</B></P>

<P STYLE="margin: 0">&nbsp;</P>

<P STYLE="margin: 0"></P>

<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-transform: uppercase; text-align: center">&nbsp;</P>

<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-transform: uppercase; text-align: center">&nbsp;</P>

<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-transform: uppercase; text-align: center"><U>AMENDMENT
NO. 1 TO At-THE-market issuance SALES AGREEMENT</U><BR>
<BR></P>

<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-transform: uppercase; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-transform: uppercase; text-align: right"><FONT STYLE="font-weight: normal; text-transform: none">May
7, 2018</FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-transform: uppercase; text-align: right">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-transform: uppercase; text-align: center"><FONT STYLE="font-weight: normal">&nbsp;</FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-transform: uppercase; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">Ladies and Gentlemen:</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">Synthetic Biologics,
Inc. (the &ldquo;<B><U>Company</U></B>&rdquo;) and FBR Capital Markets &amp; Co. (&ldquo;<U>FBR</U>&rdquo;) are parties to that
certain At-the-Market Issuance Sales Agreement dated August 5, 2016 (the &ldquo;<B><U>Original Agreement</U></B>&rdquo;). All capitalized
terms not defined herein shall have the meanings ascribed to them in the Original Agreement. The parties, together with B. Riley
FBR, Inc. (&ldquo;<B><U>B. Riley FBR</U></B>&rdquo;), intending to be legally bound, hereby amend the Original Agreement as follows:</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">1.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;All
references to &ldquo;FBR Capital Markets &amp; Co.&rdquo; and &ldquo;FBR&rdquo; set forth the Original Agreement are revised to
read &ldquo;B. Riley FBR, Inc.&rdquo; and &ldquo;B. Riley FBR&rdquo; respectively.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">2.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Section
1 is deleted in its entirety and replaced with the following:</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&ldquo;<U>Issuance
and Sale of Shares</U>. &nbsp;Company agrees that, from time to time during the term of this Agreement, on the terms and subject
to the conditions set forth herein, it may issue and sell through the Agent, shares of common stock (the shares to be offered and
sold hereunder being referred to as the &ldquo;<B><U>Placement Shares</U></B>&rdquo;) of the Company, par value $0.001 per share
(the &ldquo;<B><U>Common Stock</U></B>&rdquo;);&nbsp;<I>provided</I>,&nbsp;<I>however</I>, that in no event shall the Company issue
or sell through the Agent such number or dollar amount of Placement Shares that would (a) exceed the number or dollar amount of
shares of Common Stock registered on the effective Registration Statement (as defined below) pursuant to which the offering is
being made, (b) exceed the number of authorized but unissued shares of Common Stock, (c) exceed the number or dollar amount of
shares of Common Stock permitted to be sold under Form S-3 (including General Instruction I.B.6 thereof, if applicable) or (d)
exceed the number or dollar amount of Common Stock for which the Company has filed a Prospectus Supplement (as defined below) (the
lesser of (a), (b), (c) and (d), the &ldquo;<B><U>Maximum Amount</U></B>&rdquo;). Notwithstanding anything to the contrary contained
herein, the parties hereto agree that compliance with the limitations set forth in this Section 1 on the number or the dollar amount
of Placement Shares issued and sold under this Agreement shall be the sole responsibility of the Company and that Agent shall have
no obligation in connection with such compliance. The issuance and sale of Placement Shares through Agent will be effected pursuant
to the Registration Statement (as defined below) filed by the Company and which will be declared effective by the Securities and
Exchange Commission (the &ldquo;<B><U>Commission</U></B>&rdquo;), although nothing in this Agreement shall be construed as requiring
the Company to use the Registration Statement to issue Common Stock.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify; text-indent: 0.5in">The Company
has filed or will file, in accordance with the provisions of the Securities Act of 1933, as amended, and the rules and regulations
thereunder (the &ldquo;<B><U>Securities Act</U></B>&rdquo;), with the Commission a registration statement on Form S-3 , including
a base prospectus, relating to certain securities, including the Placement Shares to be issued from time to time by the Company,
and which incorporates by reference documents that the Company has filed or will file in accordance with the provisions of the
Securities Exchange Act of 1934, as amended (the &ldquo;<B><U>Exchange Act</U></B>&rdquo;), and the rules and regulations thereunder.
The Company will, if necessary, prepare a prospectus supplement to the base prospectus included as part of the registration statement,
which prospectus supplement relates to the Placement Shares to be issued from time to time by the Company pursuant to this Agreement
(the &ldquo;<B><U>Prospectus Supplement</U></B>&rdquo;). The Company will furnish to the Agent, for use by the Agent, copies of
the base prospectus included as part of such registration statement, as supplemented by the Prospectus Supplement, relating to
the Placement Shares to be issued from time to time by the Company. The Company may file, if necessary, one or more additional
registration statements from time to time that will contain a base prospectus and related prospectus or prospectus supplement,
if applicable (which shall be a Prospectus Supplement), with respect to the Placement Shares. Except where the context otherwise
requires, such registration statement(s), including all documents filed as part thereof or incorporated by reference therein, and
including any information contained in a Prospectus (as defined below) subsequently filed with the Commission pursuant to Rule
424(b) under the Securities Act or deemed to be a part of such registration statement(s) pursuant to Rule 430B of the Securities
Act, is herein called the &ldquo;<B><U>Registration Statement</U></B>.&rdquo; The base prospectus or base prospectuses, including
all documents incorporated or deemed incorporated therein by reference, included in the Registration Statement, as it may be supplemented
by the Prospectus Supplement, in the form in which such prospectus or prospectuses and/or Prospectus Supplement have most recently
been filed by the Company with the Commission pursuant to Rule 424(b) under the Securities Act, together with the then issued Issuer
Free Writing Prospectus(es) (defined below), is herein called the &ldquo;<B><U>Prospectus</U></B>.&rdquo;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify; text-indent: 0.5in">Any reference
herein to the Registration Statement, any Prospectus Supplement, Prospectus or any Issuer Free Writing Prospectus shall be deemed
to refer to and include the documents, if any, incorporated by reference therein (the &ldquo;<B><U>Incorporated Documents</U></B>&rdquo;),
including, unless the context otherwise requires, the documents, if any, filed as exhibits to such Incorporated Documents. Any
reference herein to the terms &ldquo;amend,&rdquo; &ldquo;amendment&rdquo; or &ldquo;supplement&rdquo; with respect to the Registration
Statement, any Prospectus Supplement, the Prospectus or any Issuer Free Writing Prospectus shall be deemed to refer to and include
the filing of any document under the Exchange Act on or after the most-recent effective date of the Registration Statement, or
the date of the Prospectus Supplement, Prospectus or such Issuer Free Writing Prospectus, as the case may be, and incorporated
therein by reference. For purposes of this Agreement, all references to the Registration Statement, the Prospectus or to any amendment
or supplement thereto shall be deemed to include the most recent copy filed with the Commission pursuant to its Electronic Data
Gathering Analysis and Retrieval System, or if applicable, the Interactive Data Electronic Application system when used by the
Commission (collectively, &ldquo;<B><U>EDGAR</U></B>&rdquo;).&rdquo;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&nbsp;&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">3.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The
reference in Section 3 to &ldquo;NYSE MKT LLC&rdquo; shall be deleted and replaced with &ldquo;NYSE American.&rdquo;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: left">&nbsp;&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">4.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Section
6(vv) is deleted in its entirety and replaced with the following:</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify; text-indent: 0.5in">&ldquo;<U>Market
Capitalization</U>.&nbsp; At the time the Registration Statement was or will be declared effective, and at the time the Company&rsquo;s
most recent Annual Report on Form 10-K was filed with the Commission, the Company met or will meet the then applicable requirements
for the use of Form S-3 under the Securities Act, including, but not limited to, General Instruction I.B.6 of Form S-3, if applicable.&nbsp;
The aggregate market value of the outstanding voting and non-voting common equity (as defined in Securities Act Rule 405) of the
Company held by persons other than affiliates of the Company (pursuant to Securities Act Rule 144, those that directly, or indirectly
through one or more intermediaries, control, or are controlled by, or are under common control with, the Company) (the &ldquo;<B>Non-Affiliate
Shares</B>&rdquo;), was approximately $44,622,269 (calculated by multiplying (x) the highest price at which the common equity of
the Company closed on the Exchange within 60 days of the date of this Agreement times (y) the number of Non-Affiliate Shares).&rdquo;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">5.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Section
14 is hereby amended to replace,</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&ldquo;FBR Capital Markets &amp;
Co.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">1300 North 17<SUP>th</SUP> Street</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">Suite 1400</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">Arlington, VA 22209</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">Attention: Legal Department&rdquo;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">With,</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&ldquo;B. Riley FBR, Inc.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">299 Park Avenue</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">New York, NY 10171</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">Attention:&#9;General Counsel</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">Telephone: &#9;(212) 457-9947&#9;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">Email:&#9;atmdesk@brileyfbr.com&rdquo;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">6.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Schedule
3 is hereby amended to replace,</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&ldquo;<U>The Agent</U></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font: 10pt Times New Roman, Times, Serif; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 0.5in; padding: 0; text-align: justify; text-indent: 0">&nbsp;</TD>
    <TD STYLE="width: 2in; padding: 0; text-align: justify; text-indent: 0"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Margery Fischbein </FONT></TD>
    <TD STYLE="padding: 0; text-align: justify; text-indent: 0"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">mfiscbein@fbr.com</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding: 0; text-align: justify; text-indent: 0">&nbsp;</TD>
    <TD STYLE="padding: 0; text-align: justify; text-indent: 0"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Ryan Loforte </FONT></TD>
    <TD STYLE="padding: 0; text-align: justify; text-indent: 0"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">rloforte@fbr.com</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding: 0; text-align: justify; text-indent: 0">&nbsp;</TD>
    <TD STYLE="padding: 0; text-align: justify; text-indent: 0"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Patrice McNicoll </FONT></TD>
    <TD STYLE="padding: 0; text-align: justify; text-indent: 0"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">pmcnicoll@fbr.com</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding: 0; text-indent: 0">&nbsp;</TD>
    <TD STYLE="padding: 0; text-indent: 0"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Keith Pompliano </FONT></TD>
    <TD STYLE="padding: 0; text-indent: 0"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">kpompliano@fbr.com</FONT></TD></TR>
</TABLE>


<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">With a copy to mlvatmdesk@mlvco.com&rdquo;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">With</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&ldquo;<U>B. Riley FBR</U></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="width: 100%; font: 10pt Times New Roman, Times, Serif; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 0.5in; padding: 0; text-indent: 0">&nbsp;</TD>
    <TD STYLE="width: 2in; padding: 0; text-align: justify; text-indent: 0"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Matthew Feinberg</FONT></TD>
    <TD STYLE="padding: 0; text-align: justify; text-indent: 0"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">mfeinberg@brileyfbr.com</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding: 0; text-indent: 0">&nbsp;</TD>
    <TD STYLE="padding: 0; text-align: justify; text-indent: 0"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Ryan Loforte</FONT></TD>
    <TD STYLE="padding: 0; text-align: justify; text-indent: 0"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">rloforte@brileyfbr.com</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding: 0; text-indent: 0">&nbsp;</TD>
    <TD STYLE="padding: 0; text-align: justify; text-indent: 0"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Patrice McNicoll</FONT></TD>
    <TD STYLE="padding: 0; text-align: justify; text-indent: 0"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">pmcnicoll@brileyfbr.com</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding: 0; text-indent: 0">&nbsp;</TD>
    <TD STYLE="padding: 0; text-indent: 0"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Keith Pompliano</FONT></TD>
    <TD STYLE="padding: 0; text-indent: 0"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">kpompliano@brileyfbr.com</FONT></TD></TR>
</TABLE>


<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">with a copy to atmdesk@brileyfbr.com&rdquo;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">7.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;All
references to &ldquo;August 5, 2016&rdquo; set forth in Schedule 1 of the Original Agreement are revised to read &ldquo;August
5, 2016 (as amended by Amendment No. 1 to At-the-Market Issuance Sales Agreement, dated May 7, 2018)&rdquo;.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">8.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Except
as specifically set forth herein, all other provisions of the Original Agreement shall remain in full force and effect.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">9.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<U>Entire
Agreement; Amendment; Severability</U>. This Amendment No. 1 to the Original Agreement together with the Original Agreement (including
all schedules and exhibits attached hereto and thereto and Placement Notices issued pursuant hereto and thereto) constitutes the
entire agreement and supersedes all other prior and contemporaneous agreements and undertakings, both written and oral, among the
parties hereto with regard to the subject matter hereof. All references in the Original Agreement to the &ldquo;Agreement&rdquo;
shall mean the Original Agreement as amended by this Amendment No. 1; <I>provided, however</I>, that all references to &ldquo;date
of this Agreement&rdquo; in the Original Agreement shall continue to refer to the date of the Original Agreement, and the reference
to &ldquo;time of execution of this Agreement&rdquo; set forth in Section 13(a) shall continue to refer to the time of execution
of the Original Agreement.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">10.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<U>Applicable
Law; Consent to Jurisdiction</U>. This amendment shall be governed by, and construed in accordance with, the internal laws of the
State of New York without regard to the principles of conflicts of laws. Each party hereby irrevocably submits to the non-exclusive
jurisdiction of the state and federal courts sitting in the City of New York, borough of Manhattan, for the adjudication of any
dispute hereunder or in connection with any transaction contemplated hereby, and hereby irrevocably waives, and agrees not to assert
in any suit, action or proceeding, any claim that it is not personally subject to the jurisdiction of any such court, that such
suit, action or proceeding is brought in an inconvenient forum or that the venue of such suit, action or proceeding is improper.
Each party hereby irrevocably waives personal service of process and consents to process being served in any such suit, action
or proceeding by mailing a copy thereof (certified or registered mail, return receipt requested) to such party at the address in
effect for notices to it under this amendment and agrees that such service shall constitute good and sufficient service of process
and notice thereof. Nothing contained herein shall be deemed to limit in any way any right to serve process in any manner permitted
by law.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">11.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<U>Waiver
of Jury Trial</U>. The Company and B. Riley FBR each hereby irrevocably waives any right it may have to a trial by jury in respect
of any claim based upon or arising out of this amendment or any transaction contemplated hereby.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">12.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<U>Counterparts</U>.
This amendment may be executed in two or more counterparts, each of which shall be deemed an original, but all of which together
shall constitute one and the same instrument. Delivery of an executed amendment by one party to the other may be made by facsimile
transmission.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify">&nbsp;</P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>&nbsp;</B></P>


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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">If the foregoing correctly
sets forth the understanding among the Company and B. Riley, please so indicate in the space provided below for that purpose, whereupon
this letter shall constitute a binding amendment to the Original Agreement between the Company and B. Riley FBR.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 5in">Very truly yours,</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3in"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 225pt; text-align: justify"><FONT STYLE="text-transform: uppercase">&nbsp;</FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 225pt; text-align: justify"><FONT STYLE="text-transform: uppercase">&nbsp;</FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 5.25in; text-align: justify"><FONT STYLE="text-transform: uppercase"><B>SYNTHETIC
BIOLOGICS INC.</B></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 5.25in; text-align: justify"><FONT STYLE="text-transform: uppercase">&nbsp;</FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 5.25in; text-align: left">By:&#9;/s/ Steven Shallcross</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 5.25in; text-align: left">Name: Steven A. Shallcross</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 5.25in; text-align: left">Title:&#9;Interim Chief Executive
Officer and</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 5.25in; text-align: justify">Chief Financial Officer</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 5.25in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 5.25in; text-align: justify"><FONT STYLE="text-transform: uppercase"><B>&nbsp;</B></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 5.25in; text-align: justify"><FONT STYLE="text-transform: uppercase"><B>&nbsp;</B></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 5.25in; text-align: justify"><FONT STYLE="text-transform: uppercase"><B>B.
Riley FBR, INc.</B></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 5.25in; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 5.25in; text-align: justify">By: /s/Patrice McNicoll&#9;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 5.25in; text-align: justify">Name: Patrice McNicoll&#9;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 5.25in; text-align: justify">Title: Co-Head of Investment
Banking</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 225pt; text-align: justify"><FONT STYLE="text-transform: uppercase"><B>&nbsp;</B></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 225pt; text-align: justify"><FONT STYLE="text-transform: uppercase"><B>&nbsp;</B></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 225pt; text-align: justify"><FONT STYLE="text-transform: uppercase"><B>&nbsp;</B></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center"><I>[Signature page to Amendment No. 1 to
At-the-Market Issuance Sales Agreement]</I></P>



<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 225pt; text-align: justify"><FONT STYLE="text-transform: uppercase"><B>&nbsp;</B></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 225pt; text-align: justify"><FONT STYLE="text-transform: uppercase"><B>&nbsp;</B></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 225pt; text-align: justify"><FONT STYLE="text-transform: uppercase"><B></B></FONT></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 225pt; text-align: justify"><FONT STYLE="text-transform: uppercase"><B></B></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 225pt; text-align: justify"><FONT STYLE="text-transform: uppercase"><B>&nbsp;</B></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 3in">&nbsp;</P>



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