RE:mRNA vaccine company Phase 2 trial fails on wrong biomarker Gritstone's disappointing result puts into doubt Granite's chances of an accelerated approval; Gritstone previously hoped to pursue this based on molecular response data, which has drawn a blank. The company now intends to use PFS as the primary endpoint in a future pivotal study.
This shift in endpoint is surely down to Granite's complete failure to show a molecular response benefit. Molecular response was the primary outcome of the phase 2 portion of Granite's ongoing phase 2/3 trial in first-line metastatic microsatellite-stable colorectal cancer – a “cold” tumour that has seen little benefit from immunotherapy. There was a 30% molecular response rate in the Granite cohort, compared with 42% in the chemo arm, Gritstone revealed on April 01, 2024.