ESMO: Merck's Keytruda matches Opdivo on key survival metric for post-surgery melanoma

Keytruda Opdivo
Merck's Keytruda and Bristol's Opdivo both bear approvals in stage 3 adjuvant melanoma. (Merck, Bristol Myers Squibb)

Merck’s Keytruda is battling Bristol Myers Squibb’s Opdivo in stage 3, post-surgery melanoma, and it just racked up trial results that could help it even the playing field.

At 3 1/2 years of median follow-up, 65.3% of Keytruda patients hadn’t seen their cancer spread to a faraway part of the body, Merck said Saturday at the European Society for Medical Oncology’s virtual congress.

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That figure matches up to the 66% distant metastasis-free survival (DMFS) rate Opdivo posted at the three-year mark in results unveiled last year from the Checkmate-238 study.

What makes that rate so important? Once melanoma spreads to other parts of the body, “we generally don’t speak of being able to cure those patients,” Scot Ebbinghaus, Merck's vice president of clinical research, said. “The best shot we have is to prevent the metastases from occurring in the first place, and that’s what (the) endpoint in this trial is showing.”

Both drugs already bear approvals in this setting, which they scored after showing they could help keep patients from relapsing after surgery. Keytruda “is being used pretty commonly out in the real world already as a standard-of-care treatment for adjuvant therapy of melanoma, as is” Opdivo, Ebbinghaus noted.

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The gold standard in cancer trials, though, are data showing that treatments can prolong lives. And while overall survival “can take a long time to read out” in adjuvant trials, “DMFS is sort of the next step in … showing that these benefits could translate, ultimately, into” life extension.

Keytruda and Opdivo have been duking it out in several cancers over the last several years, but melanoma was the original battleground. The two drugs nabbed their first FDA green lights back in 2014, with Keytruda debuting in September and Opdivo following with its own nod in December.