OncoMed Presents Data on Multiple Anti-Cancer Stem Cell Programs at American Association for Cancer Research Annual Meeting

OncoMed Presents Data on Multiple Anti-Cancer Stem Cell Programs at American
Association for Cancer Research Annual Meeting

REDWOOD CITY, Calif. and SAN DIEGO, April 8, 2014 (GLOBE NEWSWIRE) -- OncoMed
Pharmaceuticals, Inc. (Nasdaq:OMED), a clinical-stage company developing novel
therapeutics that target cancer stem cells (CSCs), or tumor-initiating cells,
today announced data from an oral presentation and eight poster presentations
at the American Association of Cancer Research (AACR) Annual Meeting in San
Diego, CA April 5-9, 2014. The research presented at AACR highlight OncoMed's
drug discovery platforms along with preclinical and biomarker discoveries on
its clinical-stage product candidates and several emerging product candidates.
A brief summary of each presentation is provided below.

"The nine presentations at this year's AACR Annual Meeting demonstrate the
breadth and depth of OncoMed's preclinical research and discovery
work.Encompassing many of our clinical- and preclinical- stage candidates,
data being presented this week highlight the potent anti-cancer stem cell
activity seen across our portfolio, the opportunities to combine our compounds
with standard-of-care, and our ongoing biomarker identification efforts being
applied to programs in clinical development," said John Lewicki, PhD,
Executive Vice President, Chief Scientific Officer.

Oral Presentation

Timothy Hoey, PhD, OncoMed's Senior Vice President of Cancer Biology, gave an
oral presentation entitled "Using PDX models for anticancer drug screening" as
part of a Methods Workshop on Applications of Patient Derived Xenograft Models
to Translational Cancer Research.Dr. Hoey discussed the central role of
OncoMed's patient-derived tumor bank to evaluate anti-tumor and anti-cancer
stem cell activity of its novel drug candidates; provide insights into
potential clinical indications and dosing regimens; and generate and evaluate
predictive biomarker hypotheses for application in clinical trials.OncoMed
has developed a large bank of patient-derived tumors, comprising more than 200
tumors from many different tumor types, including the detailed phenotypic,
functional and genomic characterization of each tumor.

Poster Presentations

Clinical-stage Programs

Belinda Cancilla, PhD, Director, presented abstract #910, "NOTCH3 expression
is predictive of efficacy in pancreas tumor models treated with OMP-59R5, a
monoclonal antibody targeting the NOTCH2 and NOTCH3 receptors," in the
Predictive Biomarker 1 Poster Session.Expression of NOTCH3 mRNA by
next-generation sequencing in pancreatic tumor models correlated with response
to OncoMed's anti-Notch2/3 antibody, OMP-59R5, where tumor efficacy correlated
with NOTCH3 biomarker levels.A Research Use Only (RUO) qPCR assay for
quantifying NOTCH3 mRNA expression using Formalin-Fixed, Paraffin-Embedded
(FFPE) samples and an immunohistochemistry (IHC) assay for measuring levels of
NOTCH3 protein in tumor samples have been developed. These assays will be used
to correlate NOTCH3 levels with patient response in ALPINE, a Phase 1b/2
clinical trial of OMP-59R5 in first-line advanced pancreatic cancer patients.
OMP-59R5 is part of OncoMed's collaboration with GlaxoSmithKline (GSK).

Marcus Fischer, Associate Scientist, presented abstract #3048, "OMP-59R5
(Anti-Notch2/3) inhibits tumor growth and reduces cancer stem cell frequency
in patient derived SCLC xenografts," in the Cancer Stem Cell Phenotype and
Function 2Poster Session.OMP-59R5 was highly effective in reducing tumor
growth and cancer stem cell populations in models of small cell lung cancer
(SCLC). Treatment with OMP-59R5 increased the expression of differentiation
markers and reduced CSC and Notch pathway genes.OncoMed is currently
evaluating OMP-59R5 in the Phase 1b/2 PINNACLE trial in patients with SCLC. 

Dr. Hoey also presented abstract #1898, "The combination of
gemcitabine/nab-paclitaxel and anti-DLL4 (demcizumab) produces synergistic
growth inhibition, delays tumor recurrence and reduces tumor initiating cells
in pancreatic cancer," as part of the New Diagnostics, Therapeutic Targeting,
and Response Assessments Poster Session.Demcizumab, in combination with
nab-paclitaxel (Abraxane^®) and gemcitabine produced profound anti-tumor
activity and anti-CSC activity in a series of pancreatic tumor xenografts.The
triple combination of demcizumab, Abraxane and gemcitabine was more
efficacious compared with the combination of demcizumab plus gemcitabine alone
and in several instances led to shrinkage of tumors to undetectable
levels.OncoMed is currently testing the combination of demcizumab with
Abraxane/gemcitabine in a Phase 1b study of advanced pancreatic cancer
patients and plans to initiate a Phase 2 study in this patient population
later this year.The demcizumab program is part of OncoMed's collaboration
with Celgene.

Chun Zhang, Senior Scientist II, presented abstract #2830, "Predictive
biomarker identification for response to vantictumab (OMP-18R5; anti-Frizzled)
by mining gene expression data of human breast cancer xenografts," in the
Predictive Biomarkers 2 Poster Session.A novel six-gene signature was derived
based on the responsiveness of breast cancer xenografts to vantictumab and has
been used successfully to accurately predict the responsiveness of six
additional xenograft models to this antibody.A clinical use test for this
six-gene signature is under development and will be used in the analysis of
patients from OncoMed's ongoing Phase 1b study of vantictumab in breast
cancer. Vantictumab is part of OncoMed's Wnt pathway collaboration with Bayer
Pharma AG (Bayer).

Pete Yeung, Associate Scientist, presented abstract #1907, "Wnt pathway
antagonist OMP-54F28 (FZD8-Fc) inhibits tumor growth and reduces
tumor-initiating cell frequency in patient-derived hepatocellular carcinoma
and ovarian cancer xenograft models," in the Cancer Stem Cell Phenotype and
Function 1 poster session.Researchers at OncoMed evaluated OMP-54F28 in
models of hepatocellular cancer (HCC) and ovarian cancer, two of the three
indications that are currently being pursued in Phase 1b studies of this
therapeutic candidate.OMP-54F28 demonstrated activity as a single-agent and
in combination with sorafenib in four HCC models and exhibited single agent
and combination activity with paclitaxel in two ovarian cancer xenografts.A
marked reduction in CSC frequency was observed following treatment with
OMP-54F28 alone and in combination with chemotherapy in both tumor
types.OMP-54F28 also induced the differentiation of these tumors and blocked
Wnt pathway genes.OMP-54F28 is part of OncoMed's collaboration with Bayer.

Wan-Ching Yen, PhD, Senior Scientist II presented abstract #4547, "Enhanced
anti-tumor effect of WNT pathway antagonists in combination with taxanes," in
the Cell Cycle Mechanisms of Anticancer Drug Action Poster Session.The
combination of Wnt pathway antagonists with taxanes in patient-derived
pancreatic or ovarian xenografts showed additivity and/or synergy that
exceeded that observed when Wnt blockade is combined with DNA synthesis
inhibitors gemcitabine and carboplatin.Both Wnt pathway antagonists and
taxanes are active at the G2/M phase of the cell cycle, which is thought to
explain observed synergies.Taxanes are currently being combined with either
vantictumab or OMP-54F28 in multiple ongoing Phase 1b studies.

"The presentations at AACR by OncoMed's scientists reinforce the clinical data
being generated across our development programs," said Jakob Dupont, OncoMed's
Chief Medical Officer."These research results provide valuable insights on
potential combination regimens, where the addition of standard-of-care
therapies may best enhance the activity of our anti-cancer stem cell
candidates and guide our predictive biomarker programs." 

Emerging Preclinical Programs

Dr. Yen also presented abstract #207, "Dual targeting of DLL4 and VEGF
signaling by a novel bispecific antibody inhibits tumor growth and reduces
cancer stem cell frequency," in the Stem Cell Expansion and Cancer Stem Cell
Targeting Poster Session. OMP-305B83, OncoMed's novel high affinity bispecific
antibody targeting DLL4 and VEGF demonstrated significant in vivo anti-tumor
efficacy in a range of solid tumor xenografts, delayed tumor recurrence
following termination of chemotherapy, and decreased the frequency of cancer
stem cells. Dual inhibition of these two targets appears to exhibit additive
anti-tumor activity at doses where blockade of either target alone elicited
sub-optimal activity. OncoMed expects to file an Investigational New Drug
(IND) application with the US Food and Drug Administration for OMP-305B83 in
the second half of 2014.

Austin Gurney, PhD, Senior Vice President of Molecular and Cellular Biology at
OncoMed, presented abstract #1764, "Inhibition of R-spondin (RSPO) signaling
reduces the growth of multiple human tumors," in the New Targets and Agents 1
Poster Session. Inhibition of RSPO-LGR signaling with novel anti-RSPO
antibodies inhibited tumor growth in numerous patient derived xenograft
models, including ovarian, colon, non-small cell lung and pancreatic cancers.
The RSPO blockade was effective in reducing tumor growth in tumors
overexpressing RSPO, including tumors with genetic translocations, suggesting
that levels of RSPO expression may serve as biomarkers in identifying patients
most likely to respond to RSPO blockade.OncoMed expects to file an IND for
its lead anti-RSPO3 antibody in late 2014 or early 2015.

Both the anti-DLL4/anti-VEGF antibodies and anti-RSPO programs are encompassed
within OncoMed's collaboration with Celgene.

"Our strong presence at this year's AACR Annual Meeting reflects the
productivity of OncoMed's platform technologies and our commitment to
continued discovery research, proprietary human tumor xenograft models, and
predictive biomarkers," said Paul J. Hastings, Chairman and Chief Executive
Officer."OncoMed's preclinical and translational medicine work informs and
supports the efforts of our development organization, which is currently
conducting 15 clinical trials for five anti cancer stem cell agents, and fuels
the growth of our pipeline of anti-cancer stem cell therapeutics, as
exemplified by the presentations of in vivo tumor efficacy data for our
pre-IND candidates, OMP-305B83 and Anti-RSPO3."

About Cancer Stem Cells

Cancer stem cells, or CSCs, are the subpopulation of cells in a tumor
responsible for driving growth and metastasis of the tumor. CSCs, also known
as tumor-initiating cells, exhibit certain properties which include the
capacity to divide and give rise to new CSCs via a process called self-renewal
and the capacity to differentiate or change into the other cells that form the
bulk of the tumor. Common cancer drugs target bulk tumor cells but have
limited impact on CSCs, thereby providing a path for recurrence of the
tumor.OncoMed's product candidates target CSCs by blocking self-renewal and
driving differentiation of CSCs toward a non-tumorigenic state, and also
impact bulk tumor cells. OncoMed believes its product candidates are distinct
from the current generations of chemotherapies and targeted therapies, and
have the potential to significantly impact cancer treatment and the clinical
outcome of patients with cancer.

About OncoMed Pharmaceuticals

OncoMed Pharmaceuticals is a clinical-stage company focused on discovering and
developing novel therapeutics targeting cancer stem cells. OncoMed has five
anti-cancer product candidates in clinical development, including demcizumab
(Anti-DLL4, OMP-21M18), OMP-59R5 (Anti-Notch2/3), OMP-52M51 (Anti-Notch1),
vantictumab (Anti-Fzd7, OMP-18R5), and OMP-54F28 (Fzd8-Fc), which target key
cancer stem cell signaling pathways including Notch and Wnt. OncoMed has two
other antibodies in preclinical development, OMP-305B83 (Anti-DLL4/Anti-VEGF
bispecific) and Anti-RSPO3, with Investigational New Drug filings planned for
late 2014 or early 2015. OncoMed is also pursuing discovery of additional
novel anti-CSC product candidates. OncoMed has formed strategic alliances with
Celgene Corporation, Bayer Pharma AG and GlaxoSmithKline (GSK). Additional
information can be found at the company's website: www.oncomed.com.

Forward-Looking Statements

To the extent that statements contained in this press release are not
descriptions of historical facts regarding OncoMed Pharmaceuticals, they are
forward-looking statements reflecting the current beliefs and expectations of
management made pursuant to the safe harbor provisions of the Private
Securities Litigation Reform Act of 1995, including OncoMed's expectations
regarding the ability of OncoMed to advance its research and development
pipeline, including its discovery and preclinical pipeline and its anti-CSC
therapeutics in clinical trials; OncoMed's ability to discover and develop
novel anti-CSC therapeutics; the tolerability of OncoMed's product candidates
at efficacious doses; the potential of OncoMed's product candidates to
significantly impact cancer treatment and the clinical outcome of patients
with cancer; the potential for successful development of predictive biomarkers
for OncoMed's product candidates; the timing of clinical trials for OncoMed's
product candidates; and the timing of Investigational New Drug filings for
OncoMed's product candidates, including OMP-305B83 and Anti-RSPO3.Such
forward-looking statements involve substantial risks and uncertainties that
could cause OncoMed's clinical development programs, 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 uncertainties inherent in the preclinical and
clinical development process; the risks and uncertainties of the regulatory
approval process; OncoMed's dependence on its collaboration partners,
including Celgene, GSK and Bayer, for the funding of its partnered programs;
OncoMed's ability to raise additional capital to support the development of
its unpartnered programs; OncoMed's dependence on the development and
marketing efforts of its partners for the commercial success of its partnered
product candidates; OncoMed's reliance on third parties to conduct certain
preclinical studies and all of its clinical trials; OncoMed's reliance on
single source third-party contract manufacturing organizations to manufacture
and supply its product candidates; OncoMed's ability to validate, develop and
obtain regulatory approval for companion diagnostics; OncoMed's ability to
achieve market acceptance and commercial success of its product candidates
once regulatory approval is achieved; OncoMed's ability to discover, develop
and commercialize additional product candidates; the ability of competitors to
discover, develop or commercialize competing products more quickly or more
successfully; OncoMed's dependence on its Chairman and Chief Executive
Officer, its Chief Scientific Officer, its Chief Medical Officer and other key
executives; risk of third party claims alleging infringement of patents and
proprietary rights or seeking to invalidate OncoMed's patents or proprietary
rights; and the ability of OncoMed's proprietary rights to protect its
technologies and product candidates.OncoMed 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 OncoMed's business in general, see OncoMed's Annual Report on Form 10-K for
the fiscal year ended December 31, 2013, filed with the Securities and
Exchange Commission on March 18, 2014.

CONTACT: Investor Contact:
         OncoMed Pharmaceuticals
         Shari Annes
         Investor Relations
         (650) 888-0902
         Media Inquiries:
         BCC Partners
         Karen L. Bergman or
         Michelle Corral
         (650) 575-1509 or (415) 794-8662
         kbergman@bccpartners.com or

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