Akeso's drug beats Keytruda in a head-to-head trial

Keytruda is the best-selling drug in the world, made by Merck. On Tuesday, a smaller challenger beat it. Akeso developed the drug with partner Summit Therapeutics. Ivonescimab outlived Keytruda in a head-to-head Phase 3 lung cancer trial in China. It's the first time a rival drug has beaten Keytruda on actual survival, not just tumor shrinkage.

Ivonescimab isn't just another copy of Keytruda. It blocks two things at once. PD-1 is the protein cancer cells use to hide from the immune system. VEGF is a protein tumors use to grow new blood vessels. An early look at this trial last year didn't convince investors; the survival benefit hadn't yet ruled out chance. This final analysis did. Merck has led cancer immunotherapy for a decade on Keytruda's roughly $30 billion a year in sales. A drug that beats it on survival, the hardest bar to clear, is the biggest threat that lead has faced.

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Will this hold up outside China? HARMONi-2 only enrolled Chinese patients, and cancer drugs can perform differently across populations. Summit still needs trials in the US and Europe before regulators there will consider approving it. If those confirm what China's trial found, Merck has a real problem on its hands.