OMP-54F28 is one of five anti-CSC product candidates currently being advanced through clinical studies by OncoMed and the company's second distinct Wnt-pathway modulating therapeutic to enter the clinic as part of the collaboration between OncoMed and Bayer. OncoMed's first Wnt pathway anti-cancer stem cell compound, vantictumab (OMP-18R5, Anti-FZD7), is being advanced into three Phase 1b combination clinical studies. The first of these trials was recently initiated in patients with advanced breast cancer to evaluate the combination of vantictumab with paclitaxel. Bayer retains an option to exclusively license OMP-54F28 and/or vantictumab at any point through completion of certain Phase 1 trials.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's product candidates target CSCs by blocking self-renewal and driving differentiation of CSCs toward a non-tumorigenic state, and also impact bulk tumor cells. 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 OMP-54F28 (Fzd8-Fc) OMP-54F28 is a first-in-class fusion protein that has shown broad anti-CSC and anti-tumor activity in patient-derived xenograft tumor models. OMP-54F28 inhibits a key signaling pathway in cancer, the Wnt pathway. Specifically, OMP-54F28 consists of the extracellular ligand-binding domain of the Frizzled 8 receptor and the Fc domain of a human IgG1 antibody. OMP-54F28 selectively binds Wnt ligands, which are activators of Wnt signaling. OMP-54F28 is currently in Phase 1a in patients with refractory solid tumors. Data from the OMP-54F28 solid tumor trial were presented at the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics in Boston, MA, in October 2013. OMP-54F28 is part of OncoMed's collaboration with Bayer Pharma AG.