<SEC-DOCUMENT>0001193125-23-160757.txt : 20230605
<SEC-HEADER>0001193125-23-160757.hdr.sgml : 20230605
<ACCEPTANCE-DATETIME>20230605163757
ACCESSION NUMBER:		0001193125-23-160757
CONFORMED SUBMISSION TYPE:	6-K
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20230605
FILED AS OF DATE:		20230605
DATE AS OF CHANGE:		20230605

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Mereo Biopharma Group plc
		CENTRAL INDEX KEY:			0001719714
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			X0
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		6-K
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-38452
		FILM NUMBER:		23993120

	BUSINESS ADDRESS:	
		STREET 1:		ONE CAVENDISH PLACE
		STREET 2:		FOURTH FLOOR
		CITY:			LONDON
		STATE:			X0
		ZIP:			W1G0QF
		BUSINESS PHONE:		4403330237300

	MAIL ADDRESS:	
		STREET 1:		ONE CAVENDISH PLACE
		STREET 2:		FOURTH FLOOR
		CITY:			LONDON
		STATE:			X0
		ZIP:			W1G0QF
</SEC-HEADER>
<DOCUMENT>
<TYPE>6-K
<SEQUENCE>1
<FILENAME>d498858d6k.htm
<DESCRIPTION>6-K
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<Center><DIV STYLE="width:8.5in" align="left">
 <P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:0pt;border-bottom:1px solid #000000">&nbsp;</P>
<P STYLE="line-height:3.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000">&nbsp;</P> <P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>UNITED STATES </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>SECURITIES AND EXCHANGE COMMISSION </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>WASHINGTON, D.C. 20549 </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center>
<P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>FORM <FONT
STYLE="white-space:nowrap">6-K</FONT> </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center>
<P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>REPORT OF
FOREIGN PRIVATE ISSUER </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>PURSUANT TO RULE <FONT STYLE="white-space:nowrap">13a-16</FONT> or
<FONT STYLE="white-space:nowrap">15d-16</FONT> </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>UNDER THE&nbsp;SECURITIES EXCHANGE ACT OF 1934 </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>For the month of June, 2023 </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Commission File Number: <FONT STYLE="white-space:nowrap">001-38452</FONT> </B></P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center> <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:24pt; font-family:Times New Roman" ALIGN="center"><B>MEREO BIOPHARMA GROUP PLC </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(Translation of registrant&#146;s name into English) </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center>
<P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>4<SUP
STYLE="font-size:75%; vertical-align:top">th</SUP> Floor, One Cavendish Place,</B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>London, W1G 0QF, United Kingdom</B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Address of principal executive office) </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center>
<P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Indicate by check mark whether
the registrant files or will file annual reports under cover of Form <FONT STYLE="white-space:nowrap">20-F</FONT> or Form <FONT STYLE="white-space:nowrap">40-F.</FONT> </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">Form
<FONT STYLE="white-space:nowrap">20-F&nbsp;&nbsp;&#9746;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Form</FONT> <FONT STYLE="white-space:nowrap">40-F&nbsp;&nbsp;&#9744;</FONT> </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Indicate by check mark if the registrant is submitting the Form <FONT STYLE="white-space:nowrap">6-K</FONT> in paper as permitted by Regulation <FONT
STYLE="white-space:nowrap">S-T</FONT> Rule 101(b)(1):&nbsp;&nbsp;&#9744; </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Indicate by check mark if the registrant is submitting the Form <FONT
STYLE="white-space:nowrap">6-K</FONT> in paper as permitted by Regulation <FONT STYLE="white-space:nowrap">S-T</FONT> Rule 101(b)(7):&nbsp;&nbsp;&#9744; </P> <P STYLE="font-size:10pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:0pt;border-bottom:1px solid #000000">&nbsp;</P> <P STYLE="line-height:3.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000">&nbsp;</P>
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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B><U>Exhibit Index </U></B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="bottom" ALIGN="center"><B>Exhibits</B></TD>
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<TD VALIGN="top" NOWRAP>99.1</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"><A HREF="d498858dex991.htm">Joint press release of Ultragenyx Pharmaceutical Inc. and Mereo BioPharma Group plc dated June&nbsp;5, 2023. </A></TD></TR>
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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>SIGNATURES </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">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, thereunto duly authorized. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Date: June&nbsp;5, 2023 </P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><DIV ALIGN="right">
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<TD VALIGN="top" COLSPAN="3"><B>MEREO BIOPHARMA GROUP PLC</B></TD></TR>
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<TD HEIGHT="16"></TD>
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<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Charles Sermon</P></TD></TR>
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<TD VALIGN="top"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top">Name:&nbsp;Charles Sermon</TD></TR>
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<TD VALIGN="top"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top">Title:&nbsp;General Counsel</TD></TR>
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<Center><DIV STYLE="width:8.5in" align="left">
 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="right"><B>Exhibit 99.1 </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Ultragenyx and Mereo BioPharma Announce Positive Data from the Ongoing Phase 2/3 </B><B><I>Orbit </I></B><B> </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Study of Setrusumab (UX143) in Osteogenesis Imperfecta (OI) </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><I>Pediatric data show substantial induction of bone production in 1 week and a large increase in </I></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><I>bone formation within 3 months of initiating monthly setrusumab treatment </I></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><I>Phase 3 sites beginning to screen patients </I></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><I>Conference call to discuss data planned for 5 p.m. Eastern Time </I></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>NOVATO, </B><B>Calif</B><B> and LONDON, UK </B>&#151; June&nbsp;5, 2023 &#151; Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE) and Mereo BioPharma Group plc
(NASDAQ: MREO) today announced data from the dose-selection Phase 2 portion of the Phase 2/3 <I>Orbit </I>study showing that setrusumab rapidly induced bone production in <FONT STYLE="white-space:nowrap">OI-affected</FONT> patients. Across all
patients evaluated, as of the data cut off, setrusumab demonstrated statistically significant increases in levels of serum P1NP, a sensitive marker of bone formation, and a substantial and significant improvement in bone mineral density (BMD) by 3
months. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">&#147;The rate of increasing bone mineralization we&#146;re observing on DXA scans is striking, unlike anything I have typically seen with
bisphosphonate therapy. This increase in bone mass underscores the potential to make denser and stronger bone,&#148; said Gary Gottesman, MD, Professor of Pediatrics and Medicine, Washington University School of Medicine. </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">As of the data cut off, serum P1NP levels through at least 1 month of treatment were available from all 24 patients enrolled in <I>Orbit </I>and demonstrated
that treatment with setrusumab significantly increased serum P1NP in both dosing cohorts, peaking at one to two weeks and again, as expected, after the <FONT STYLE="white-space:nowrap">2-month</FONT> dosing timepoint. In the 20 mg/kg cohort, there
was a mean serum P1NP increase of 57% from baseline over the first month. Because of the higher baseline P1NP level in younger patients, this represents an approximate <FONT STYLE="white-space:nowrap">8-fold</FONT> greater increase in serum P1NP
over 1 month in pediatric and adolescent patients when compared to adult OI patients. The absolute effect of setrusumab on increasing serum P1NP over the <FONT STYLE="white-space:nowrap">1-month</FONT> period with the 20 mg/kg dose, was
approximately 80% of the effect achieved with the 40 mg/kg dose, demonstrating a dose response. Patients on placebo at the <FONT STYLE="white-space:nowrap">1-month</FONT> timepoint (n=4) showed no significant change in mean serum P1NP from baseline.
</P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">The large increase in BMD observed in the <I>Orbit </I>patient population over the first 3 months was consistent with the rapid increase in serum P1NP
levels and was similar to results that took 1 year to achieve in the ASTEROID study in adult OI patients. Lumbar spine BMD data were available in 17 of 24 <I>Orbit </I>patients at the <FONT STYLE="white-space:nowrap">3-month</FONT> timepoint.
Treatment with setrusumab for 3 months resulted in an increase in lumbar spine BMD from baseline of 9.4% at 20 mg/kg (n=10) which represents a substantial mean change in <FONT STYLE="white-space:nowrap">Z-score</FONT> of +0.65. Treatment with 40
mg/kg (n=7) resulted in a 9.8% BMD increase. Patients on placebo at the <FONT STYLE="white-space:nowrap">3-month</FONT> timepoint (n=2) showed no significant change in BMD or change in lumbar spine <FONT STYLE="white-space:nowrap">Z-score.</FONT>
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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">&#147;The dramatic lumbar spine BMD improvements in children at 3 months show that growing bones are more
dynamic, and we anticipate the potential for a greater effect on bone formation and strength in younger patients with maturing bones,&#148; said Eric Crombez, M.D., chief medical officer at Ultragenyx. &#147;Based on the reports from study
investigators, we&#146;re encouraged by the impact setrusumab appears to be having on bone health so far.&#148; </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">There have been no treatment-related
serious adverse events observed in the study. Reported adverse events have been generally consistent those observed in the ASTEROID study and include infusion associated events, headache and sinusitis. There have been no reported hypersensitivity
reactions related to setrusumab. There were no safety-related differences observed between dosing groups or age groups. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">The totality of data demonstrated
meaningful response in serum P1NP and BMD across both cohorts, with the majority of the effect observed at 20 mg/kg, which is the dose planned across the setrusumab Phase 3 program. Screening has begun for the Phase 3 portion of the study, which is
designed to enroll approximately 195 patients at more than 40 sites across 12 countries. </P> <P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>Investor Conference Call and Webcast Information </B></P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Ultragenyx will host an investor conference call today, Monday, June&nbsp;5, at 2 p.m. PT / 5 p.m. ET to discuss the results. The live and replayed webcast of
the call will be available through the company&#146;s website at <U>https://ir.ultragenyx.com/events-presentations</U>. To participate in the live call, please register by clicking on the following link (<U>registration link</U>), and you will be
provided with dial in details. The replay of the call will be available for one year. </P> <P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>The Setrusumab Phase 3 Program </B></P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Ultragenyx and Mereo are developing setrusumab in pediatric and young adult patients across OI <FONT STYLE="white-space:nowrap">sub-types</FONT> I, III and IV
with two late-stage trials: the pivotal Phase 2/3 <I>Orbit</I> study and Phase 3 <I>Cosmic </I>study. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">The global, seamless Phase 2/3 <I>Orbit </I>study
is evaluating the effect of setrusumab versus placebo on fracture rate in patients aged 5 to &lt;26 years. In the Phase 2 portion, 24 patients were randomized 1:1 to receive setrusumab at one of two doses to determine the optimal dosing strategy for
Phase 3. The <I>Orbit</I> study was designed to be placebo-controlled, however the placebo arm was removed from the Phase 2 portion by amendment. All of the placebo patients enrolled in Phase 2 (n=4) were subsequently rerandomized to one of the
dosing cohorts. </P>
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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">The pivotal Phase 3 portion of the study will include approximately 195 patients, randomized 2:1 to receive
setrusumab or placebo, with a primary efficacy endpoint of annualized clinical fracture rate. All patients will transition to an extension period and receive open-label setrusumab after the Phase 3 primary analysis is complete. </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">The Phase 3<I> Cosmic </I>study is an open-label, randomized, active-controlled study in patients aged 2 to &lt;5 years evaluating setrusumab versus
intravenous bisphosphonates <FONT STYLE="white-space:nowrap">(IV-BP)</FONT> therapy on reduction in total fracture rate, including morphometric vertebral fractures. The <I>Cosmic </I>study is anticipated to start in the next few months and will
enroll approximately <FONT STYLE="white-space:nowrap">50-66</FONT> patients. </P> <P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>About Osteogenesis Imperfecta (OI) </B></P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Osteogenesis Imperfecta (OI) includes a group of genetic disorders impacting bone metabolism. Approximately 85% to 90% of OI cases are caused by mutations in
the <I>COL1A1</I> or <I>COL1A2 </I>genes, leading to either reduced or abnormal collagen and changes in bone metabolism. The collagen mutations in OI can result in increased bone brittleness, which contributes to a high rate of fractures, including
at atypical sites. Patients with OI also exhibit increased bone resorption (breakdown of old bone) and inadequate production of new bone, which leads to decreased bone mass, bone fragility and weakness. OI can also lead to bone deformities, abnormal
spine curvature, pain, decreased mobility, and short stature. No treatments are approved for OI, which affects approximately 60,000 people in the developed world. </P>
<P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>About Setrusumab (UX143) </B></P> <P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Setrusumab is a fully human
monoclonal antibody that inhibits sclerostin, a protein that acts on a key bone-signaling pathway that inhibits the maturation and activity of bone-forming cells. The goal of blocking inhibitory effects of sclerostin is to increase new bone
formation, bone mineral density and bone strength. Sclerostin inhibition also reduces excessive bone resorption, further enhancing its impact on bone density. In mouse models of OI, the use of anti-sclerostin antibodies was shown to stimulate bone
formation, improve bone mass and density, and increase bone strength against fracture force testing. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Mereo BioPharma&#146;s Phase 2b study (ASTEROID)
treatment phase of the dose-finding study of setrusumab for the treatment of OI in 112 adults was concluded in 2019. The ASTEROID study demonstrated treatment with setrusumab resulted in a clear, dose-dependent and statistically significant effect
on bone formation and bone density at multiple anatomical sites among adult participants with OI. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Ultragenyx and Mereo BioPharma are collaborating on the
development of setrusumab globally based on the collaboration and license agreement between the parties. The companies have developed a comprehensive late-stage program to continue development of setrusumab in pediatric and young adult patients
across OI <FONT STYLE="white-space:nowrap">sub-types</FONT> I, III and IV. </P>
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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>About Ultragenyx Pharmaceutical Inc. </B></P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Ultragenyx is a biopharmaceutical company committed to bringing novel products to patients for the treatment of serious rare and ultrarare genetic diseases.
The company has built a diverse portfolio of approved therapies and product candidates aimed at addressing diseases with high unmet medical need and clear biology for treatment, for which there are typically no approved therapies treating the
underlying disease. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">The company is led by a management team experienced in the development and commercialization of rare disease therapeutics.
Ultragenyx&#146;s strategy is predicated upon time- and cost-efficient drug development, with the goal of delivering safe and effective therapies to patients with the utmost urgency. </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">For more information on Ultragenyx, please visit the company&#146;s website at: <U>www.ultragenyx.com</U>. </P>
<P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>About Mereo BioPharma </B></P> <P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Mereo BioPharma is a
biopharmaceutical company focused on the development of innovative therapeutics for rare diseases. The Company has two rare disease product candidates, setrusumab for the treatment of Osteogenesis Imperfecta (OI) and alvelestat for the treatment of
severe <FONT STYLE="white-space:nowrap"><FONT STYLE="white-space:nowrap">alpha-1-antitrypsin</FONT></FONT> deficiency-associated lung disease <FONT STYLE="white-space:nowrap">(AATD-LD)</FONT> and Bronchiolitis Obliterans Syndrome (BOS). The
Company&#146;s partner, Ultragenyx Pharmaceutical, Inc., has initiated a pivotal Phase 2/3 pediatric study in young adults <FONT STYLE="white-space:nowrap">(5-25</FONT> years old) for setrusumab in OI and expects to initiate a study in pediatric
patients (&lt;5 years old) in the next few months. The partnership with Ultragenyx includes potential milestone payments of up to $254&nbsp;million and royalties to Mereo on commercial sales in Ultragenyx territories. Mereo has retained EU and UK
commercial rights and will pay Ultragenyx royalties on commercial sales in those territories. Alvelestat has received U.S. Orphan Drug Designation for the treatment of AATD, Fast Track designation from the FDA, and positive data were reported from a
Phase 2 <FONT STYLE="white-space:nowrap"><FONT STYLE="white-space:nowrap">proof-of-concept</FONT></FONT> study in North America, Europe and the UK. In addition to the rare disease programs, Mereo has two oncology product candidates in clinical
development. Etigilimab (anti-TIGIT) has completed enrollment in a Phase 1b/2 basket study evaluating its safety and efficacy in combination with an <FONT STYLE="white-space:nowrap"><FONT STYLE="white-space:nowrap">anti-PD-1</FONT></FONT> in a range
of tumor types including three rare tumors and three gynecological carcinomas&#151;cervical, ovarian, and endometrial; navicixizumab, for the treatment of late line ovarian cancer, has completed a Phase 1 study and has been partnered with OncXerna
Therapeutics, Inc. in a global licensing agreement that includes payments of up to $300&nbsp;million in milestones and royalties. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">For more information on
Mereo BioPharma, please visit <U>www.mereobiopharma.com</U> </P>
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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>Ultragenyx Forward-Looking Statements and Use of Digital Media </B></P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><I>Except for the historical information contained herein, the matters set forth in this press release, including statements related to Ultragenyx&#146;s
expectations and projections regarding its future operating results and financial performance, business plans and objectives for UX143, expectations regarding the tolerability and safety of UX143, and future clinical and regulatory developments for
UX143 are forward-looking statements within the meaning of the &#147;safe harbor&#148; provisions of the Private Securities Litigation Reform Act of 1995. Such forward-looking statements involve substantial risks and uncertainties that could cause
our clinical development programs, collaboration with third parties, future results, performance or achievements to differ significantly from those expressed or implied by the forward-looking statements. Such risks and uncertainties include, among
others, the uncertainty of clinical drug development and unpredictability and lengthy process for obtaining regulatory approvals, the ability of the company and Mereo BioPharma to successfully develop UX143, the company&#146;s ability to achieve its
projected development goals in its expected timeframes, risks related to adverse side effects, risks related to reliance on third party partners to conduct certain activities on the company&#146;s behalf, the potential for any license or
collaboration agreement, including the company&#146;s collaboration agreement with Mereo to be terminated, smaller than anticipated market opportunities for the company&#146;s products and product candidates, manufacturing risks, competition from
other therapies or products, and other matters that could affect sufficiency of existing cash, cash equivalents and short-term investments to fund operations, the company&#146;s future operating results and financial performance, the timing of
clinical trial activities and reporting results from same, and the availability or commercial potential of Ultragenyx&#146;s products and drug candidates. Ultragenyx undertakes no obligation to update or revise any forward-looking statements. For a
further description of the risks and uncertainties that could cause actual results to differ from those expressed in these forward-looking statements, as well as risks relating to the business of Ultragenyx in general, see Ultragenyx&#146;s
Quarterly Report on Form <FONT STYLE="white-space:nowrap">10-Q</FONT> filed with the Securities and Exchange Commission (SEC) on May&nbsp;5, 2023, and its subsequent periodic reports filed with the SEC. </I></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><I>In addition to its SEC filings, press releases and public conference calls, Ultragenyx uses its investor relations website and social media outlets to
publish important information about the company, including information that may be deemed material to investors, and to comply with its disclosure obligations under Regulation FD. Financial and other information about Ultragenyx is routinely posted
and is accessible on Ultragenyx&#146;s Investor Relations website (<U>https://ir.ultragenyx.com/</U>) and LinkedIn website
(<U><FONT STYLE="white-space:nowrap"><FONT STYLE="white-space:nowrap">https://www.linkedin.com/company/ultragenyx-pharmaceutical-inc-/mycompany/</FONT></FONT></U>). </I></P>
<P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>Mereo BioPharma Forward-Looking Statements </B></P> <P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><I>This press
release contains &#147;forward-looking statements.&#148; All statements other than statements of historical fact contained in this press release are forward-looking statements within the meaning of Section&nbsp;27A of the United States Securities
Act of 1933, as amended (the &#147;Securities Act&#148;), and Section&nbsp;21E of the United States Securities Exchange Act of 1934, as amended (the &#147;Exchange Act&#148;). Forward-looking statements usually relate to future events and
anticipated revenues, earnings, cash flows or other aspects of Mereo BioPharma&#146;s operations or operating results. Forward-looking statements are often identified by the words &#147;believe,&#148; &#147;expect,&#148; &#147;anticipate,&#148;
&#147;plan,&#148; &#147;intend,&#148; &#147;foresee,&#148; &#147;should,&#148; &#147;would,&#148; &#147;could,&#148; &#147;may,&#148; &#147;estimate,&#148; &#147;outlook&#148; and similar expressions, including the negative thereof. The absence of
these words, however, does not mean that the statements are not forward-looking. These forward-looking statements are based on Mereo BioPharma&#146;s current expectations, beliefs and assumptions concerning future developments and business
conditions and their potential effect on Mereo. While management believes that these forward-looking statements are reasonable as and when made, there can be no assurance that future developments affecting Mereo BioPharma will be those that it
anticipates. </I></P>
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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><I>All of Mereo BioPharma&#146;s forward-looking statements involve known and unknown risks and
uncertainties some of which are significant or beyond its control and assumptions that could cause actual results to differ materially from Mereo BioPharma&#146;s historical experience and its present expectations or projections. </I></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><I>Such risks and uncertainties include, among others, the uncertainties inherent in the clinical development process; Mereo BioPharma&#146;s reliance on
third parties to conduct and provide funding for its clinical trials; Mereo&#146;s dependence on enrollment of patients in its clinical trials; and Mereo&#146;s dependence on its key executives. You should carefully consider the foregoing factors
and the other risks and uncertainties that affect Mereo BioPharma&#146;s business, including those described in the &#147;Risk Factors&#148; section of its latest Annual Report on Form <FONT STYLE="white-space:nowrap">20-F,</FONT> reports on Form <FONT
STYLE="white-space:nowrap">6-K</FONT> and other documents furnished or filed from time to time by Mereo BioPharma with the Securities and Exchange Commission. Mereo BioPharma wishes to caution you not to place undue reliance on any forward-looking
statements, which speak only as of the date hereof. Mereo BioPharma undertakes no obligation to publicly update or revise any of our forward-looking statements after the date they are made, whether as a result of new information, future events or
otherwise, except to the extent required by law</I>. </P> <P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>Contacts </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><U>Ultragenyx Pharmaceutical Inc</U>.</P> <P STYLE="font-size:12pt; margin-top:0pt; margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><U>Investors</U></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Joshua Higa</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><FONT STYLE="white-space:nowrap"><FONT STYLE="white-space:nowrap">415-475-6370</FONT></FONT></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><U>ir@ultragenyx.com</U></P> <P STYLE="font-size:12pt; margin-top:0pt; margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><U>Media</U></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Jeff Blake</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><FONT STYLE="white-space:nowrap"><FONT STYLE="white-space:nowrap">415-612-7784</FONT></FONT></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman"><U>media@ultragenyx.com</U></P></TD>
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<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><U>Mereo BioPharma Group plc</U></P> <P STYLE="font-size:12pt; margin-top:0pt; margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Denise Scots-Knight, Chief Executive Officer</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Christine Fox, Chief
Financial Officer</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">+44 (0)333 023 7300</P> <P STYLE="font-size:12pt; margin-top:0pt; margin-bottom:0pt">&nbsp;</P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Burns McClellan (Investor Relations Advisor to Mereo)</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Lee Roth
+01 <FONT STYLE="white-space:nowrap"><FONT STYLE="white-space:nowrap">646-930-4406</FONT></FONT></P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman"><U>investors@mereobiopharma.com</U></P></TD></TR>
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