ASCO: Merck's Keytruda-chemo combo approach racks up more support with positive overall survival data

New Keytruda image
Merck's Keytruda-chemo combo last week nabbed an FDA approval in first-line lung cancer.

If investors needed more reason to feel positively about Merck’s Keytruda-chemo combo, they just got it.

With Wednesday’s ASCO abstract release came the finding of an overall survival benefit for patients on the tandem in Merck’s Keynote-021G trial, Bernstein analyst Tim Anderson wrote in a note to clients. As the data have matured, OS curves have separated in the Merck pair’s favor, and a 0.69 hazard ratio points its way, too.

Related: Pressure mounts on Bristol-Myers, AstraZeneca as Merck bags Keytruda chemo combo approval

The finding isn’t a shock—at least, not to Anderson, who predicted an OS benefit when the European Medicines Agency (EMA) agreed to accept Merck’s chembo combo filing for review. While the FDA, as of earlier this month, has already approved the regimen in first-line lung cancer, “the bar to filing/approval is typically much higher” in Europe, and until yesterday, all the company had shown from Keynote-021G was positive overall response rate and progression-free survival results.

Now, though, the OS evidence supports “the overall concept of adding together” a PD-1/PD-L1 med and chemo, Anderson wrote. “There have been concerns that chemotherapy might adversely impact the immune system, thereby rendering immune-activation by a PDx ineffective if given in combination, and negating any OS benefit,” he wrote.

And while Keynote-021G is still only in phase 2, “this new data is nonetheless very encouraging.”

Related: Editor's Corner—Notes on a crazy 2 weeks that transformed immuno-oncology

It’s been a good couple of weeks for Merck—and, by extension, Roche, which is testing a chemo combo of its own. The FDA green-lighted the Keytruda-chemo one-two punch last Wednesday, marking “the first true endorsement of the general ‘chemo combo’ approach,” Anderson wrote at the time.

Now, the pressure’s on Bristol-Myers Squibb and AstraZeneca, which have gone in another direction with their combos. The drugmakers have matched their checkpoint inhibitors up with CTLA-4 meds, and it’s not yet clear if those will succeed—and if they do, how they will stack up against the Merck-Roche approach.

That doesn’t mean the pressure’s off the latter two drugmakers in the combo arena, though. Roche’s combo, which adds chemo to Tecentriq, could end up looking better or worse than Merck’s, and Merck’s larger phase 3 study could turn up better or worse results than its phase 2, Anderson has noted.