Bad vibes continue for Merck

Yesterday Merck admitted that its Tigit-Keytruda coformulation MK-7684A was numerically inferior to chemo in the phase 2 Keyvibe-002 lung cancer trial, and the question now is what that means for other studies of the Tigit, vibostolimab. The trial was a long shot since patients had already failed on one checkpoint inhibitor and chemotherapy, and following the disappointing performance of vibostolimab in Keynote-001 three years ago. Data from the open-label arm of Keyvibe-002 showed that the vibostolimab-Keytruda combo was inferior to docetaxel on the primary endpoint of PFS in NSCLC patients who had progressed on anti-PD(L)1 and platinum-based chemo. Keyvibe-002 also has a blinded comparison of the combo plus docetaxel versus docetaxel alone, and Merck is continuing this. But attention will now shift to the much bigger phase 3 study Keyvibe-003, in the first-line treatment of NSCLC patients with PD(L)1 expression of at least 1%, and while this is a different setting the chance of success now looks even slimmer. That said, both Mizuho and SVB analysts point to the Keymaker-U02 substudy 02C in neoadjuvant stage III melanoma, data from which is expected at AACR next month, as giving closer read-through to the Keyvibe programme in an earlier setting.