Merck treads on Sanofi, Regeneron's turf with Keytruda's latest skin cancer OK

Merck's Keytruda boasts a long list of indications in skin cancer, lung cancer and beyond. (Merck)

It’s a feeling Sanofi and Regeneron’s immuno-oncology rivals know all too well: Merck & Co.’s Keytruda just moved into a market you had cornered. Now, the pair is about to get its first taste of that particular brand of competition.

The FDA Wednesday approved Keytruda in recurrent or metastatic cutaneous squamous cell carcinoma that can’t be cured by surgery or radiation. Regulators based their decision on data from the Keynote-629 trial, which showed the drug could spur a response in 34% of patients who hadn’t yet received another immunotherapy.

At the time of the trial check-in, the median duration of response hadn’t been reached, and some patients were still seeing benefit from Keytruda past the 13-month mark.

RELATED: Sixth-to-market Sanofi scores niche nod for PD-1 player—and blockbuster wannabe—Libtayo

Now, Merck’s superstar will make its way into an I-O arena previously occupied only by Sanofi and Regeneron’s Libtayo, the most recent addition to the cohort of marketed PD-1/PD-L1 drugs. But the partners have time on their side: Libtayo has been racking up sales in the indication since it hit the scene back in October 2018, pulling in $61.7 million for Regeneron through the first three months of 2020.

Still, nobody likes company from a rival—particularly when that rival is the class’s bestseller, with more than $11 billion in 2019 sales.

But two can play that game. Sanofi and Regeneron are currently working to tread on Merck’s turf in previously untreated lung cancer after putting up data in April that showed Libtayo, when pitted against chemotherapy, could cut the risk of death by 32.4% for patients with high levels of biomarker PD-L1.

RELATED: Sanofi, Regeneron take aim at Keytruda with Libtayo's first lung cancer win

Of course, wresting lung cancer share from Merck will be no easy task—and, at least for now, it’s Keytruda in the regulatory spotlight. The latest go-ahead comes before the FDA’s June 29 decision deadline and adds to a long list of indications for the blockbuster in skin cancer, bladder cancer, kidney cancer and beyond.