Tigit mystery deepens with Merck's clinical expansion

Renewed enthusiasm has marked Tigit as a hot target in immuno-oncology, but developments have taken place almost in secret. In January Roche started a huge pivotal programme with tiragolumab, and told Vantage it had waited until the last possible moment to disclose this so as not to tip off its biggest rival, Merck & Co. For its part the latter company has quietly been expanding its phase I trial of MK-7684, which initially targeted 120 subjects but now seeks to enrol 432. And just last week Merck fired its own shot at Roche, listing on clinicaltrials.gov three new mid-stage studies that look like they could support approval of its Tigit combos across three melanoma settings. Roche has just listed the Skyskraper-01 and 04 tiragolumab trials in NSCLC and cervical cancer respectively, and five more settings have yet to be revealed. Still unknown is what clinical data have driven such enthusiasm; Evercore ISI analysts last week wrote that “it’s clear there is a signal ... but we haven’t got additional disclosures yet”. Roche was due to present early Tigit data at April’s AACR, but the meeting has been rescheduled owing to the Covid-19 pandemic.