OncoMed Doses First Patient in Phase 1b Portion of anti-TIGIT Clinical Trial  

Expanded Phase of Trial will Assess anti-TIGIT in Combination with anti-PD1

REDWOOD CITY, Calif., June 12, 2018 (GLOBE NEWSWIRE) -- OncoMed Pharmaceuticals Inc. (NASDAQ:OMED), a clinical-stage biopharmaceutical company focused on discovering and developing novel anti-cancer therapeutics, today announced that the first patient has been dosed in the company’s Phase 1b portion of the Phase 1a/1b clinical trial of anti-TIGIT (OMP-313M32) in combination with anti-PD1 (nivolumab). TIGIT (T-cell immunoreceptor with Ig and ITIM domains) is a next generation checkpoint receptor, and upon activation by the PVR ligand, a protein broadly expressed on tumor cells, it blocks T-cell activation. OncoMed’s anti-TIGIT candidate is an IgG1 monoclonal antibody checkpoint inhibitor which binds to the human TIGIT receptor on T-cells with a goal of improving the activation and effectiveness of T-cell and NK cell tumor-killing activity.

“The dosing of the first patient in the Phase 1b portion of the anti-TIGIT trial marks an important milestone in the advancement of this therapeutic candidate through the clinic, where we will be evaluating the potential synergy of our anti-TIGIT monoclonal antibody with anti-PD1,” said John Lewicki, Ph.D., president and chief executive officer of OncoMed. “We look forward to continuing our exploration of the potential anti-tumor activity of anti-TIGIT and its ability to combine safely with anti-PD1 in key clinical oncology settings. Simultaneously, dose escalation in the Phase 1a portion of the trial is nearing completion and dose expansion in select tumor types is planned.”

The Phase 1b portion of the open-label Phase 1a/1b clinical trial is designed to assess safety, tolerability, preliminary efficacy, and biomarkers with escalating doses of anti-TIGIT in combination with anti-PD1 in the treatment of patients with selected advanced or metastatic solid tumors who have progressed after treatment with anti-PD1 or anti-PD-L1. The Phase 1a/1b trial is being conducted at 5 centers in the U.S., and OncoMed currently plans to enroll approximately 12 patients in the Phase 1b portion of the study. The trial will define a dosing regimen that could provide the basis for expanded studies of anti-TIGIT in combination with anti-PD1.

TIGIT blocks T-cells from attacking tumor cells and is similar in structure and function to the inhibitory protein PD-1. OncoMed's anti-TIGIT antibody (OMP-313M32) is intended to activate the immune system through multiple mechanisms and enable anti-tumor activity. At the 2018 AACR Annual Meeting, OncoMed presented preclinical data (Abstract 5627) which demonstrated that anti-TIGIT treatment reduced the abundance of regulatory T-cells (Tregs) within tumors in animal models. Mechanistic studies demonstrated an important contribution of effector function for anti-tumor efficacy. Using a surrogate anti-TIGIT antibody, potent single-agent dose-dependent anti-tumor efficacy was demonstrated on large established CT26 WT tumors. Anti-TIGIT efficacy was shown to require effector function for tumor growth inhibition and biomarker analysis demonstrated reduction of Treg frequency and activation of T-cells and NK cells as part of the mechanism of action of anti-TIGIT. CD226, a co-receptor for TIGIT’s ligands PVR and PVRL2, was significantly upregulated in T-cells, Tregs and NK cells, reflecting a feedback loop activated by the inhibition of TIGIT activity. Additionally in a human tissue study, TIGIT expression on Tregs was found to be considerably higher than on CD8+ T-cells in multiplexed IHC panels across a panel of multiple solid tumors types. This program is part of OncoMed's Celgene collaboration.

About OncoMed Pharmaceuticals
OncoMed Pharmaceuticals is a clinical-stage biopharmaceutical company focused on discovering and developing novel anti-cancer therapeutics. OncoMed has internally discovered a broad pipeline of investigational drugs intended to address the fundamental biology driving cancer's growth, resistance, recurrence and metastasis. Anti-TIGIT (OMP-313M32), navicixizumab (anti-DLL4/VEGF bispecific, OMP-305B83), and rosmantuzumab (anti-RSPO3, OMP-131R10) are part of OncoMed's strategic alliance with Celgene Corporation. OncoMed is independently developing GITRL-Fc (OMP-336B11), as well as continuing to pursue new drug discovery research. For further information about OncoMed Pharmaceuticals, please see 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, without limitation, OncoMed’s intentions and expectations regarding the anti-tumor activity of anti-TIGIT; the number of patients to be enrolled in the Phase 1b portion of the anti-TIGIT trial; the potential for expanded studies of anti-TIGIT in combination with anti-PD1; the continued advancement of anti-TIGIT in the clinic; and the potential synergy and safety of anti-TIGIT in combination with anti-PD1. 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; OncoMed's ability to raise additional capital to support the development of its unpartnered programs; and OncoMed's dependence on its key executives. 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 filed with the U.S. Securities and Exchange Commission (SEC) on March 9, 2018, OncoMed’s Quarterly Report on Form 10-Q filed with the SEC on May 8, 2018, and OncoMed's other current and periodic reports filed with the SEC.

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