OncoMed Pharmaceuticals, Inc. Initiates Phase I Clinical Trial For Anti-RSPO3 Antibody

REDWOOD CITY, Calif., July 28, 2015 (GLOBE NEWSWIRE) -- OncoMed Pharmaceuticals, Inc. (NASDAQ:OMED), a clinical-stage company developing novel anti-cancer stem cell and immuno-oncology therapeutics, today announced dosing of the first patient in its anti-RSPO3 antibody (OMP-131R10) Phase 1a/1b clinical trial. Anti-RSPO3 is the first drug in its class to target the R-spondin-LGR pathway, an important cancer stem cell pathway identified by OncoMed researchers.

"The inhibition of RSPO3 has shown robust preclinical activity against a number of solid tumor types. In this trial, we look forward to establishing a suitable dose and exploring this antibody's safety and initial efficacy," said Jakob Dupont, M.D., OncoMed's Chief Medical Officer. "In addition, studies using our human tumor xenograft models have demonstrated a strong correlation between activity and RSPO3 biomarkers as well as potent activity in the colorectal cancer setting, which we will examine in the second part of this comprehensive Phase1a/1b trial."

The Phase 1a/1b clinical trial is initially enrolling patients with advanced refractory solid tumors. Patients will receive escalating doses of anti-RSPO3 until disease progression. The open-label study is designed to assess the safety, pharmacokinetics, pharmacodynamics and initial evidence of efficacy of the anti-RSPO3 antibody. Once a single-agent dose has been identified, biomarker-selected patients will be enrolled in a Phase 1a expansion arm to obtain additional preliminary information on possible anti-tumor activity. In the Phase 1b portion of the trial, anti-RSPO3 will also be tested in second-line colorectal cancer patients in combination with the chemotherapeutic standard of care in metastatic colon cancer, known as FOLFIRI (folinic acid, fluorouracil and irinotecan). The trial is being conducted at five sites in the United States.

Dr. Gail Eckhardt, Professor, Division of Medical Oncology and Stapp-Harlow Endowed Chair at the University of Colorado, is a Principal Investigator of the study who treated the first patient on the clinical trial. Dr. Eckhardt commented, "RSPO3 is an exciting new therapeutic target in solid tumors and in particular in colorectal cancer. OncoMed's OMP-131R10 is a novel antibody approach that will hopefully provide clinical benefit and therapeutic options for cancer patients."

R-spondin proteins bind to or activate leucine-rich repeat containing G-coupled receptors (LGRs) and blocking this activity has been shown to inhibit tumor growth. In preclinical studies OncoMed's anti-RSPO3 antibody demonstrated robust in vivo anti-tumor efficacy as a single agent and in combination with standard of care across a range of solid tumors, including colon, lung, ovarian, and pancreatic cancers, among others. The anti-RSPO3 antibody delayed tumor recurrence following termination of chemotherapy, and decreased the frequency of cancer stem cells.

The anti-RSPO3 antibody represents the third drug in the clinic that is part of OncoMed's collaboration with Celgene.

About OncoMed Pharmaceuticals

OncoMed Pharmaceuticals is a clinical-stage company focused on discovering and developing novel anti-cancer stem cell and immuno-oncology therapeutics. OncoMed has seven anti-cancer product candidates in clinical development, including demcizumab (anti-DLL4, OMP-21M18), tarextumab (anti-Notch2/3, OMP-59R5), brontictuzumab (anti-Notch1, OMP-52M51), anti-DLL4/VEGF bispecific antibody (OMP-305B83), vantictumab (anti-FZD7, OMP-18R5), ipafricept (FZD8-Fc, OMP-54F28) and anti-RSPO3 (OMP-131R10), which each target key cancer stem cell signaling pathways including Notch, Wnt and R-spondin LGR. OncoMed is also pursuing discovery of additional novel anti-CSC and cancer immunotherapy 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 its ability to establish a suitable dose for anti-RSPO3 and advance anti-RSPO3 through Phase1a/1b; the correlation between RSPO3 biomarkers and the activity of anti-RSPO3; and the ability of anti-RSPO3 to provide clinical benefit and therapeutic options for cancer patients, including colorectal cancer patients. 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 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; 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, 2014, filed with the Securities and Exchange Commission (SEC) on March 12, 2015, and OncoMed's Quarterly Report on Form 10-Q for the fiscal quarter ended March 31, 2015, filed with the SEC on May 7, 2015.

Contact:

OncoMed Pharmaceuticals

Michelle Corral

Investor Relations and Corporate Communications

michelle.corral@oncomed.com

(650) 995-8373

Shari Annes

Annes Associates

shari.annes@oncomed.com

(650) 888-0902

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