OncoMed and Celgene Announce Strategic Collaboration Advancing Multiple Anti-Cancer Stem Cell Therapeutics to Offer Potential

OncoMed and Celgene Announce Strategic Collaboration Advancing Multiple
Anti-Cancer Stem Cell Therapeutics to Offer Potential Benefits to Cancer

Celgene Invests in OncoMed's Demcizumab and up to Five Additional Preclinical
     Biologics Programs; OncoMed Leads Early Clinical Trials and Retains
        Co-Development, Co-Commercialization and Profit-Sharing Rights

OncoMed to Receive $177.25 Million Upfront, Including a $22.25 Million Equity

 OncoMed to Host a Conference Call This Morning for Investors at 8:30 a.m. ET

REDWOOD CITY, Calif., Dec. 3, 2013 (GLOBE NEWSWIRE) -- OncoMed
Pharmaceuticals, Inc. (Nasdaq:OMED) and Celgene Corporation (Nasdaq:CELG)
today announced an agreement to jointly develop and commercialize up to six
anti-cancer stem cell (CSC) product candidates from OncoMed's biologics
pipeline, including demcizumab (OMP-21M18, Anti-DLL4).

OncoMed will control and conduct initial clinical studies at which point
Celgene has an option to license worldwide rights to up to six novel anti-CSC
therapeutic candidates. OncoMed retains global co-development and U.S.
co-commercialization rights for five of the six anti-CSC product candidates
with 50/50 U.S. profit sharing, and royalties to be received in other
territories. Celgene will also have research, development and
commercialization rights to small molecule compounds in an undisclosed cancer
stem cell pathway.

Celgene obtains an exclusive option on one of OncoMed's most advanced clinical
candidates, demcizumab, during or after the completion of certain future
planned Phase II clinical trials to be conducted by OncoMed.Demcizumab is
currently in three Phase Ib clinical studies in combination with
standard-of-care therapeutics, including a trial in patients with first-line
advanced pancreatic cancer.Subsequent to option exercise, the parties will
co-develop demcizumab, sharing global development costs on a 1/3 OncoMed and
2/3 Celgene basis.The companies will co-commercialize demcizumab in the
United States with 50/50 profit sharing.Outside the United States, Celgene
would lead development and commercialization, with OncoMed eligible to receive
milestones and tiered double-digit royalties on sales outside the United

In addition to demcizumab, the collaboration includes up to five preclinical-
or discovery-stage biologics programs:OncoMed's anti-DLL4/VEGF bispecific
antibody and up to four additional biologics programs targeting either the
RSPO-LGR CSC pathway or an additional undisclosed CSC pathway.Celgene obtains
exclusive options on these programs during or after completion of certain
Phase I clinical trials to be conducted by OncoMed.For the anti-DLL4/VEGF
bispecific antibody and three of the four additional biologics programs,
OncoMed retains 50/50 U.S. profit sharing and co-commercialization terms, plus
1/3 OncoMed and 2/3 Celgene global development cost-sharing and mid-single
digit to mid-double digit royalties outside the profit-sharing territory.On
the fourth biologics program, Celgene would receive an exclusive worldwide
license, with OncoMed receiving high-single digit to mid-double digit
royalties on worldwide sales.Celgene also obtains an option to conduct small
molecule research, development, and commercialization in an undisclosed CSC
pathway, with OncoMed eligible to receive milestones and low- to mid-single
digit royalties on any resulting small molecule anti-cancer product

Under the terms of the agreement, OncoMed will receive an upfront payment of
$155 million, and Celgene will also purchase approximately $22.25 million in a
private placement of newly issued shares of OncoMed's common stock at a price
of $15.13 per share.

The collaboration also includes option exercise payments and payments for
achievement of development, regulatory and commercial milestones, paid on a
per-program basis.For demcizumab, these payments could total up to
approximately $790 million, and include an undisclosed payment for achievement
of pre-determined safety criteria in Phase II clinical trials.For the
anti-DLL4/VEGF bispecific antibody, option exercise, development, regulatory
and commercial payments could total up to $505 million.For the other four
biologics, each program is eligible for approximately $440 million of option
exercise, development, regulatory and commercial payments. OncoMed could also
receive more than $100 million in option exercise, development and regulatory
approval payments for the small molecule program.Such total payments include
milestones for regulatory approvals in multiple indications per
program.OncoMed retains worldwide rights to certain targets in multiple
pathways that do not become collaboration programs with Celgene.

"Through this major alliance with Celgene, we gain substantial resources that
will enable us to continue to discover and develop new therapeutics
independently while positioning OncoMed for substantial potential downstream
value and profits.Importantly, by retaining co-development and
co-commercialization rights to up to five biologic product candidates in our
pipeline, we expect to add commercial capabilities to our core research and
development competencies as we continue to build a premier oncology
biotherapeutics company," said Paul J. Hastings, OncoMed's Chairman and
CEO."Celgene is a preeminent biopharmaceutical innovator with a successful
track record of translating unique science into disease-altering therapies
that benefit patients, healthcare and society.We can greatly benefit from
their expertise and look forward to many years of successful collaboration."

Tom Daniel, President, Global Research & Early Development, of Celgene said,
"We are very pleased to enter into this broad based collaboration with
OncoMed, one that holds great promise for cancer patients. Demcizumab's
substantial early clinical activity warrants aggressive yet careful evaluation
in several indications where we have strength, including non-small cell lung
cancer and pancreatic cancer. The earlier partnerships in the RSPO-LGR and
another, undisclosed cancer stem cell pathway provide us complementary and
strategically valuable targeting opportunities across both biologic and small
molecule modalities in the cancer stem cell arena where OncoMed has provided
leadership and great strength."

Latham & Watkins LLP and Leerink Swann LLC acted as advisors to OncoMed for
this transaction.

OncoMed Conference Call

OncoMed management will host a conference call today beginning at 8:30 a.m.
ET/5:30 a.m. PT to discuss today's announcement regarding this strategic
collaboration with Celgene Corporation.

Analysts and investors can participate in the conference call by dialing (855)
420-0692 for domestic callers and (484) 756-4194 for international
callers.The live conference call will also be webcast and available on the
Investor Relations page of OncoMed's website at www.oncomed.com. Please access
the webcast at least 10 minutes prior to the start of the call to ensure time
for any software downloads that may be required.A telephone replay will be
available following the conclusion of the call by dialing (855) 859-2056 for
domestic callers and (404) 537-3406 for international callers using the
passcode 19812706.

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 has advanced five distinct anti-CSC targeting product
candidates into clinical trials, including demcizumab (OMP-21M18). 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 Demcizumab (OMP-21M18)

Demcizumab is a humanized monoclonal antibody that inhibits Delta-Like Ligand
4 (DLL4) in the Notch signaling pathway. Two Phase Ib combination trials of
demcizumab are ongoing: demcizumab with standard-of-care in first-line
advanced pancreatic cancer patients, and demcizumab with standard-of-care
carboplatin and pemetrexed (Alimta™) in first-line advanced non-small cell
lung cancer (NSCLC) patients.In addition, a Phase Ib/II trial of demcizumab
and paclitaxel in patients with platinum-resistant ovarian cancer is ongoing
at MD Anderson Cancer Center.Demcizumab is part of OncoMed's collaboration
with Celgene Corporation.

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, Anti-DLL4/Anti-VEGF bispecific
and Anti-RSPO3, with Investigational New Drug filings planned for as early as
2014.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, Inc., 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 expectations regarding its ability
to co-develop and co-commercialize demcizumab or any other product candidate;
the receipt of the upfront payment from Celgene and the completion of the
private placement of shares of OncoMed's common stock; OncoMed's ability to
discover and develop novel anti-CSC therapeutics; OncoMed's expectations
regarding its ability to realize substantial potential downstream value and
profits from its alliance with Celgene; and the potential of OncoMed's product
candidates to significantly impact cancer treatment and the clinical outcome
of patients with cancer.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, Bayer and GSK, for the funding of its partnered
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 Prospectus filed with the Securities and
Exchange Commission on July 18, 2013 and OncoMed's Quarterly Report on Form
10-Q for the fiscal quarter ended September 30, 2013, filed with the
Securities and Exchange Commission on November 13, 2013.

CONTACT: OncoMed Pharmaceuticals
         Shari Annes
         (650) 888-0902
         BCC Partners
         Karen L. Bergman or
         Michelle Corral
         (650) 575-1509 or (415) 794-8662
         kbergman@bccpartners.com or mcorral@bccpartners.com
         Celgene Corporation
         (908) 673-9628
         (908) 673-2275

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