Astra completes its Merck rout

With Tuesday’s US approval of Imfinzi for the periadjuvant treatment of stomach cancer AstraZeneca has completed its rout of Merck & Co in this setting. The green light, specifically for neoadjuvant and adjuvant Imfinzi plus chemo in gastric or gastroesophageal junction adenocarcinoma, is backed by an event-free survival benefit that yielded a 0.71 hazard ratio versus chemo alone, as reported at ASCO. For its part, Merck’s Keynote-585 trial, which tested Keytruda in place of Imfinzi, failed for EFS, yielding a less impressive 0.81 hazard ratio, which failed to clear a p=0.0178 statistical significance boundary (a tough bar that resulted from the alpha being split between three co-primary endpoints). One surprising aspect of Imfinzi’s success here is that Astra appears never even to have pursued metastatic gastric/GEJ settings in phase 3, shooting straight for early, periadjuvant use. The US green light imperils not only Keytruda, but also Bristol Myers Squibb’s Opdivo and BeOne’s Tevimbra; all three anti-PD-(L)1 drugs are approved first line, but whether any of them would retain meaningful efficacy in patients pretreated perioperatively with Imfinzi has just become an open question.

US physician choices in gastric/GEJ adenocarcinoma

Source: OncologyPipeline & US prescribing info.