Moderna and Merck said Thursday that adding their personalized mRNA treatment, intismeran autogene, to Keytruda after surgery reduced the relative risk of melanoma returning or causing death by 42% in a Phase 3 trial involving 1,137 people.
The international study included patients whose stage IIB to IV melanoma had been completely removed. Patients received either the vaccine with Keytruda or Keytruda with a placebo. The midpoint of the follow-up period was 24.6 months.
At two years, 82.2% of patients given the combination were alive without their melanoma returning, compared with 70% of patients given Keytruda alone. The combination also reduced the risk of cancer spreading to distant parts of the body or causing death by 38%. Intismeran is made to match mutations found in a patient’s tumor, with the aim of training the immune system to recognize cancer cells.
Keytruda helps immune cells attack tumors. The vaccine is still being studied. Results on overall survival are not yet mature.
The trial has therefore not established that the combination helps patients live longer. The companies said they are working with regulators. The detailed findings are scheduled to be presented at the European Society for Medical Oncology congress in Madrid.