Moderna’s experimental cancer vaccine cleared a hurdle no cancer vaccine has cleared before. As STAT’s Matthew Herper, Jason Mast, and Angus Chen report, a randomized, 1,137-patient Phase 3 trial found that intismeran autogene, developed with Merck and paired with Keytruda, reduced the odds that surgically removed melanoma would recur or spread.
A long-shot bet that paid off
The therapy, a neoantigen vaccine, sequences a patient’s tumor and encodes its mutations into a custom mRNA shot built in six weeks. Moderna oncologist Tal Zaks pitched the idea in 2015; the company’s board demanded a deep-pocketed partner before funding such a costly bet.
Merck nearly walked away after a Covid-driven manufacturing crunch pushed the study $40 million over budget. “At that time, I think we had pretty much written it off at Merck,” said Eric H. Rubin, who led Merck’s oncology clinical development until 2023. A 2022 Phase 2 readout — a 44% cut in recurrence risk — revived the program.
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The stakes reach beyond melanoma. Intismeran autogene rests on a decades-old idea — training the immune system to hunt a tumor’s own mutations the way it hunts a virus. Oncologists expect it to become a key melanoma treatment, and the same approach is already being tested against other cancers.
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Rubin doesn’t think this will be a one-off. “I think this is likely to be something that’s going to be helpful for a lot of cancer patients,” he said. Even Zaks, who championed the idea in 2015, wasn’t always so sure: “I honestly don’t know. All I know is that I feel like we’ve been put on earth to test this hypothesis.”


















