Merck and Moderna said on October 22 that their personalised cancer vaccine, combined with Keytruda, reduced the risk of melanoma recurrence or death by 42% compared with Keytruda alone in a major international trial. The results concern treatment after surgery, and the vaccine remains experimental.
The phase 3 INTerpath-001 study enrolled 1,137 patients with high-risk melanoma whose tumours had been completely removed. Participants were randomly assigned to Keytruda with either the vaccine, intismeran autogene, or a placebo. Reuters reported that the companies announced success in August without releasing detailed findings.
According to the companies, after median follow-up of 24.6 months, the proportion alive without recurrence at two years was 82.2% with the combination and 70.0% in the comparison group. The risk of distant spread or death fell by 38%. The 42% figure is a relative reduction in the combined endpoint, not a 42-percentage-point improvement or proof that patients live longer overall.
The vaccine is tailored to mutations in each patient's tumour to help the immune system recognise cancer cells. AP reported that the regimen involves nine injections three weeks apart. This approach aims to prevent a removed cancer from returning, rather than prevent an infection as conventional vaccines do. Keytruda is an immunotherapy already used after surgery.
The companies reported grade 3–5 treatment-related adverse events in 14.2% of patients receiving the combination and 13.4% of those receiving Keytruda alone. Fever, injection-site pain and fatigue were the most common adverse events with the combination. They said no new safety signals emerged, while overall survival data were not yet mature.
AP reported that an early public leak prompted Thursday's release before the planned Saturday presentation at the European Society for Medical Oncology congress in Madrid. The companies said they were engaging with regulators, and follow-up continues. The results support further evaluation of personalised cancer treatment, but do not establish a cure or effectiveness against other cancers.
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