Shares in Blueprint Medicines took a significant hit after it emerged that its Ayvakit (avapritinib) failed to best Bayer’s Stivarga (regorafenib) in patients with gastrointestinal stromal tumours (GIST).

Top-line results from the Phase III VOYAGER study showed that Ayvakit (avapritinib) did not significantly prolong progression-free survival (PFS) versus Stivarga in patients with third- or fourth-line GIST.

US regulators approved Ayvakit in January for adults with unresectable or metastatic GIST harbouring a PDGFR-alpha exon 18 mutation, including PDGFRA D842V mutations, but the firm said based on the data it would not be pursuing further development of the drug in GIST beyond its approved indication.

“We hope these data will reveal important insights to improve the scientific understanding of the disease and inform future innovations in GIST, and we are committed to sharing the results at a future medical meeting,” said Jeff Albers, Blueprint’s chief executive.

The company said it anticipates a decision from the European Commission on its marketing application for the treatment of adults with PDGFRA D842V-mutant GIST in the third quarter.