ASCO 2023 – Gilead/Arcus’s Tigit data worsen

If the weeks before this year’s ASCO meeting saw a notable resurgence of interest in the TIGIT mechanism, today’s update on Gilead/Arcus’s Arc-7 study could bring enthusiasm back to earth. With 7.4 months’ additional median follow-up, and six more patients in each cohort, the PFS data for domvanalimab plus zimberelimab have deteriorated versus zimberelimab monotherapy. The anti-TIGIT/PD-1 doublet had at December’s ASCO virtual plenary shown a 45% reduction in risk of progression or death and a 6.6-month increase in median PFS versus the Arcus PD-1 alone, but the numbers now stand at a 33% reduction and 3.9-month delta, today’s ASCO update revealed. What’s more, the confidence interval’s upper bound is now 1.13, having earlier stood, precariously, at exactly 1.00. True, the shape of the PFS curves and small numbers of patients make it evident that just one or two early progressers might be making the difference, but the meaningfulness of Arc-7 already seemed questionable, and the harsh reality today is that this is a dataset that is clearly not improving.

Gilead/Arcus's deteriorating Arc-7 dataset

Source: ASCO.