Merck's Keytruda makes liver-cancer headway, putting BMS and Bayer on notice

Merck's Keytruda provoked a response in more than 16% of previously treated liver cancer patients in a phase 2 study. (Merck)

Kidney cancer isn’t the only disease area where Merck’s Keytruda is moving in to challenge Bristol-Myers Squibb’s Opdivo.

At the American Society of Clinical Oncology’s GI Cancers Symposium Friday, Merck rolled out phase 2 liver cancer data that could advance it into that arena, too. The immuno-oncology superstar produced a response in 16.3% of study patients with hepatocellular carcinoma (HCC)—the most common form of liver cancer—who had been previously treated with Bayer’s Nexavar. In 1% of patients, no trace of cancer remained after treatment.

While a 16.3% response rate doesn’t sound all that impressive, it’s not much lower than the rate Opdivo posted on its way to its September liver cancer approval. The BMS drug put up an 18.2% overall response rate in a phase 1/2 study, with 3.2% of patients responding completely.

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“Unfortunately, the majority of HCC patients are diagnosed with advanced-stage disease,” Adrian Bisceglie, chief of hepatology at the Saint Louis University Liver Center, said in a statement after Opdivo won its go-ahead. Andrew Zhu, lead investigator of the Keytruda study, noted that “the durable responses observed with Keytruda monotherapy in this difficult-to-treat cancer are encouraging.”

If Keytruda can eventually land a go-ahead in the field, it’ll face some stiff competition not just from its immuno-oncology nemesis Opdivo but from Bayer, which has dominated the liver cancer landscape for years with Nexavar. Last April, the German drugmaker picked up a nod for Stivarga—its follow-up to the older Nexavar—in previously treated liver cancer, and it’s working to position the pair of meds as a sequential regimen. That way, it can keep patients who fail on Nexavar in the family, rather than ceding them to other drugmakers.

RELATED: Merck, Eisai nab Keytruda-Lenvima 'breakthrough' in quickly crowding kidney cancer field

Meanwhile, Merck is also readying Keytruda to poach territory from Opdivo in kidney cancer, where Keytruda—along with Eisai’s Lenvima—earlier this month nabbed a breakthrough designation from the FDA. It’s not the only one, though. Roche and the Pfizer-Merck KGaA team are both in that race, too, with their IO drugs Tecentriq and Bavencio, respectively.