Blueprint Medicines' Phase III VOYAGER trial of avapritinib in GIST fails endpoint

Blueprint Medicines’ (Nasdaq: BPMC) shares dropped 19% in early trade on Tuesday and were still down 17.3% at $58.63 at close, after the rare diseases and cancer immunotherapy company announced that its late-stage trial of already marketed Ayvakit (avapritinib) in an extended indication was a flop.

The US biotech firm released top-line results yesterday from the Phase III VOYAGER clinical trial of avapritinib versus regorafenib, Bayer's (BAYN: DE) Stivarga, in patients with locally-advanced unresectable or metastatic gastrointestinal stromal tumor (GIST) that did not meet the primary endpoint of an improvement in progression-free survival (PFS) for avapritinib versus regorafenib. Top-line safety data for avapritinib were consistent with those previously reported.

Blueprint Medicines plans to continue to commercialize Ayvakit in the USA for the treatment of adults with unresectable or metastatic GIST harboring a PDGFRA exon 18 mutation, including PDGFRA D842V mutations, and seek marketing approval for avapritinib for the treatment of this patient population in additional geographies. Blueprint Medicines continues to anticipate a decision from the European Commission on its marketing authorization application for the treatment of adults with PDGFRA D842V mutant GIST in the third quarter of 2020. Based on the top-line VOYAGER data, the company plans to discontinue further development of avapritinib in GIST beyond PDGFRA exon 18 mutant GIST.