REDWOOD CITY, Calif., Oct. 29, 2013 (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 that it has started a multi-center Phase 1b clinical trial of its first-in-class Wnt-pathway-targeting antibody vantictumab (OMP-18R5) with paclitaxel in breast cancer. This trial is the first of three Phase 1b trials for vantictumab that OncoMed expects to initiate this year as part of OncoMed's collaboration with Bayer Pharma AG. Interim results for the single-agent first-in-human Phase 1a trial for vantictumab in solid tumor patients were recently reported at the 2013 European Cancer Congress (ECC 2013) in Amsterdam, NL in September 2013. Additionally, vantictumab clinical biomarker data from the Phase 1a trial were presented at the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics in Boston, MA in October 2013. The Phase 1b clinical trial is a dose escalation study of the anti-CSC antibody vantictumab in combination with paclitaxel in patients with first-, second- and third-line, locally advanced or metastatic HER2 negative breast cancer. Primary objectives of the trial are to evaluate safety of this combination regimen and determine a recommended Phase 2 dose for vantictumab in combination with paclitaxel. Key secondary and exploratory objectives include evaluation of the pharmacokinetics (PK) of vantictumab, as well as the pharmacodynamics (PD) and efficacy of this combination. Tumor tissue from patients will be used to explore predictive biomarker hypotheses related to the efficacy of vantictumab. Dr. Carlos Becerra at the Baylor Sammons Cancer Center – The US Oncology Network, Dallas, TX, is the Principal Investigator who treated the first patient enrolled in this study and noted, "Breast cancer patients with advanced HER2 negative disease are in need of novel agents that have a lasting impact on their cancer. Vantictumab has the potential to have an impact for breast cancer patients in combination with standard paclitaxel chemotherapy because of its novel mechanism of action targeting cancer stem cells."