OncoMed Pharmaceuticals and its once-promising cancer stem cell technology has had a torrid time of late, with Bayer Pharma declining to exercise options on two Phase I Wnt pathway inhibitors and a trio of clinical trial failures jeopardising the future of its two other major collaborations. OncoMed rose to prominence in 2013 by partnering with Celgene in an option-based deal potentially worth up to US$3.3 B to develop up to six anti-cancer stem cell products.