Personalized mRNA melanoma vaccine clears Phase 3 endpoint after surgery

An experimental personalized skin cancer vaccine significantly reduced the risk of melanoma returning or spreading after surgery in a late-stage trial from Merck and Moderna, Fox News and NPR reported.

The INTerpath-001 study enrolled 1,137 patients worldwide with high-risk Stage IIB through Stage IV melanoma that had been surgically removed. Patients were randomly assigned to Keytruda plus the personalized mRNA vaccine, or Keytruda plus placebo.

Patients on the combination had significantly better recurrence-free survival and distant metastasis-free survival than those on Keytruda alone, the companies said. They described the result as the first positive Phase 3 trial of an mRNA-based personalized cancer therapy.

Unlike a flu shot, the vaccine is made after surgery. Doctors sample tumor and healthy tissue, then use algorithms to pick up to 34 tumor-specific neoantigens for a custom mRNA product called intismeran autogene. The goal is to train the immune system to hunt leftover cancer cells.

Dr. Murad Alam, chief of dermatology at Northwestern Medicine in Chicago, told Fox News Digital that melanomas differ from patient to patient, which is why one-size chemotherapy often fails. He called the approach nearly individualized immunotherapy aimed at people whose disease already threatens more than a small patch of skin.

Dr. Robert Vonderheide of Penn Medicine told NPR the manufacturing challenge is real because each vaccine is built for one patient, but a trial of more than 1,000 people shows the process can scale. He said overall survival data and proof of T-cell response still matter for regulators.

Merck and Moderna plan to talk with the FDA and other regulators about filings. They also plan tests in lung, bladder, and kidney cancers. Side effects looked similar to earlier studies, the companies said. The Phase 3 readout did not yet prove longer overall survival, and results apply to the studied stages after surgery, not to prevention in healthy people.