OncoMed Presents Updated Phase 1b Data For Tarextumab In Small Cell Lung Cancer

Higher Doses of Tarextumab Appear to Correlate with Improved Progression-free and Overall Survival

Redwood City, CA (GLOBE NEWSWIRE) - OncoMed Pharmaceuticals Inc. (NASDAQ:OMED), a clinical-stage company developing novel anti-cancer stem cell and immuno-oncology therapeutics, announced updated survival data from a Phase 1b clinical trial of tarextumab (anti-Notch2/3, OMP-59R5) for the treatment of small cell lung cancer.

The Phase 1b dose-escalation trial enrolled 27 previously untreated patients with extensive-stage small cell lung cancer to assess the safety, biomarker, and anti-tumor activity of tarextumab in combination with etoposide and platinum-based chemotherapy.  Doses of tarextumab ranged from 5 mg/kg to 15 mg/kg and a Phase 2 combination dose of 15mg/kg every three weeks was selected.  Among all patients in the trial, median progression-free survival (PFS) was 4.4 months and the median overall survival (OS) was 10.3 months.  Additional survival benefit was observed in 15 patients who received higher doses of tarextumab (at or above 12.5 mg/kg every three weeks) in combination with standard-of-care therapy, with a median PFS of 5.8 months and median OS of 16 months. 

“These more mature follow-up data from our Phase 1b trial of tarextumab plus chemotherapy in small cell lung cancer patients provide early signs of encouraging efficacy.  Of note, we are seeing a dose-efficacy association with a manageable side effect profile for tarextumab in the small cell lung cancer Phase 1b clinical trial.  This Phase 1b data supports our ongoing Phase 2 PINNACLE trial,” said Jakob Dupont, M.D., OncoMed’s Chief Medical Officer.  “Small cell lung cancer responds quickly to chemotherapy, but has a high rate of recurrence.  By targeting cancer stem cells, and Notch3 in particular, we hope to have a positive impact on patient outcomes.”

Additional Phase 1b Results

On-target adverse events associated with tarextumab included diarrhea, fatigue, nausea and decreased appetite.  These were mostly Grade 1 or 2 events, and manageable with supportive care.  No dose-limiting toxicities were observed at the Phase 2 dose of 15 mg/kg with platinum-based chemotherapy and etoposide. 

As previously reported at the 2015 ASCO Annual Meeting, 77 percent of evaluable patients achieved RECIST responses and six achieved stable disease for an overall clinical benefit rate of 100 percent.  Greater tumor size reductions were observed among those patients who received doses of tarextumab at or above 12.5 mg/kg. 

The updated survival data from the Phase 1b PINNACLE study were recently presented by Anne Chiang, M.D., Ph.D., of the Yale School of Medicine, during the 16th Annual Targeted Therapies of Lung Cancer Meeting.

OncoMed is conducting the PINNACLE Phase 1b/2 clinical trial of tarextumab for the treatment of small cell lung cancer. The randomized Phase 2 trial is comparing progression-free survival (PFS) outcomes for patients treated with tarextumab administered at 15 mg/kg every three weeks in combination with etoposide and cisplatin or carboplatin versus patients who receive placebo plus chemotherapy. Additionally, PFS will be assessed using a predictive biomarker for high tumor Notch3 expression. Secondary endpoints for the Phase 2 study include overall survival, overall response rate, pharmacokinetics, safety and other biomarkers. The PINNACLE study is being conducted at about 40 sites in the U.S. and is expected to enroll approximately 130 patients. Results from the Phase 2 PINNACLE trial are anticipated in early 2017.

Patients interested in participating in the tarextumab small cell lung cancer study may learn more by calling 1-866-914-7347 or emailing oncomed@emergingmed.com.

About Small Cell Lung Cancer
According to the American Cancer Society, lung cancer (both small cell and non-small cell) is the second most common cancer in men and women and is by far the leading cause of cancer death. Small cell lung cancer is expected to make up about 10%-15% of the 221,200 newly diagnosed lung cancer cases and the 158,040 deaths estimated to occur in the U.S. in 2015¹. SCLC tends to grow and spread quickly, and is typically not discovered until it has metastasized to other parts of the body (extensive stage). The current standard of care in treating small cell lung cancer is the chemotherapeutic etoposide in combination with either cisplatin or carboplatin (platinum therapy). In spite of a high sensitivity to chemotherapy and remission rates of up to 80% following initial treatment, the median overall survival is six-twelve months for patients with extensive stage disease².

About Tarextumab (anti-Notch2/3, OMP-59R5)
Tarextumab (anti-Notch2/3, OMP-59R5) is a fully human monoclonal antibody that targets the Notch2 and Notch3 receptors.  Preclinical studies have suggested that tarextumab exhibits two mechanisms of action: (1) by downregulating Notch pathway signaling, tarextumab appears to have anti-cancer stem cell effects, and (2) tarextumab affects pericytes, impacting stromal and tumor microenvironment. 

Tarextumab is part of OncoMed's collaboration with GlaxoSmithKline (GSK).  GSK has an option to obtain an exclusive license to tarextumab during certain time periods through completion of the proof-of-concept Phase 2 trials.

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 has formed strategic alliances with Celgene Corporation, Bayer Pharma AG and GlaxoSmithKline (GSK).  OncoMed is advancing its wholly owned GITRL-Fc candidate and an undisclosed immuno-oncology candidate that is part of OncoMed’s collaboration with Celgene (IO#2) toward clinical trials in the 2016-2017 timeframe. 

Please see the company's website at for additional information.

1. http://www.cancer.org/cancer/lungcancer-smallcell/detailedguide/small-cell-lung-cancer-key-statistics 
2. Jänne PA, Freidlin B, Saxman S, et al. Cancer 2002; 95:1528-38.

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 potential for tarextumab to have a positive impact on SCLC patient outcomes; the manageability of the side effect profile of tarextumab in SCLC patients; the timing of results from the PINNACLE Phase 2 trial; and the timing of advancement of OncoMed’s GITRL-Fc candidate and IO#2 immuno-oncology candidate to clinical trials. 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 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 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; and OncoMed's dependence on its Chairman and Chief Executive Officer, its Chief Scientific Officer, its Chief Medical Officer and other 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 for the fiscal year ended December 31, 2014, filed with the Securities and Exchange Commission (SEC) on March 12, 2015, OncoMed's Quarterly Report on Form 10-Q for the fiscal quarter ended March 31, 2015, filed with the SEC on May 7, 2015, OncoMed's Quarterly Report on Form 10-Q for the fiscal quarter ended June 30, 2015, filed with the SEC on August 10, 2015, and OncoMed's Quarterly Report on Form 10-Q for the fiscal quarter ended September 30, 2015, filed with the SEC on November 5, 2015.

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