ESMO: Merck details Keytruda's narrow head and neck cancer miss in phase 3

MADRID, SpainIn July, Merck’s Keytruda narrowly missed the mark in a head and neck cancer trial, failing to show it could significantly extend overall survival. And now, details of that miss are here.

Monday at the European Society for Medical Oncology annual meeting, the New Jersey drugmaker showed that in a phase 3 trial, Keytruda could only extend second-line head and neck cancer patients’ lives by 8.4 months, compared with the 7.1 months achieved with standard treatment. And the result fell just shy of the statistical significance cutoff.

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As Roy Baynes, chief medical officer of Merck Research Laboratories, said in an interview, “the drug behaved pretty much as expected,” turning up “no new safety signals.” And crossover between the study’s arms may have “contributed to the narrow miss,” he added.

While obviously disappointing to Merck, the results shouldn’t have too big an impact on the company’s regulatory status or sales. The head and neck cancer indication Merck already has isn’t in jeopardy, the drugmaker said after revealing the top-line results in May.

The fact that Merck has an ongoing study in previously untreated patients is helping, and the fact that Bristol-Myers Squibb’s Opdivo, a fellow PD-1 drug, has significant overall survival data in hand may be, too, because it suggests Keytruda's miss may have been an anomaly. Merck is confident enough in the space, in fact, to have launched a new awareness campaign in February.

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Either way, head and neck cancer isn’t a huge indication for Keytruda when it comes to sales firepower. The disease area generated just 15% of the blockbuster’s first-quarter sales, Bernstein analyst Tim Anderson wrote to clients in July, and that share has been shrinking as Keytruda’s share of the lung cancer market grows.

“Overall, this is only a small setback. Almost hitting statistical significance, and FDA deciding to not take action on the basis of these results, is reassuring, and prescribers are subsequently not likely to materially change how they use the product because of this,” he said.