OncoMed saw its shares drop more than 45% on news that its experimental pancreatic cancer drug tarextumab is unlikely to succeed in a mid-stage trial.

The Phase II ALPINE study is assessing efficacy of the stem cell therapy, in combination with Abraxane/gemcitabine, in patients with previously untreated Stage IV pancreatic cancer, with endpoints including overall survival, progression-free survival and overall response.

However, an independent data safety monitoring board has informed the firm of a statistically significant worsening of response rate and progression-free survival (PFS) in the treatment arm.

There was also a strong trend to lack of benefit in the treatment arm for overall survival, the Committee said.

Based on this information, OncoMed is unblinding the study “to carefully assess the current results and determine appropriate next steps for this fully enrolled trial”.

Tarextumab is part of OncoMed's 2007 collaboration with GlaxoSmithKline, under which the UK drug giant has the option of obtaining rights to the drug.