Moderna and Merck Melanoma Vaccine Cuts Recurrence Risk 42%
Phase III data show Merck and Moderna's personalized mRNA vaccine intismeran plus Keytruda kept 82.2% of high-risk melanoma patients cancer-free at two years.
Merck and Moderna's personalized mRNA vaccine, intismeran autogene, reduced the risk of melanoma recurrence or death by 42% at two years when added to Keytruda, according to full Phase III results the companies released Thursday.
In the INTerpath-001 trial, 82.2% of patients who received the vaccine plus Keytruda (pembrolizumab) were cancer-free after two years, compared with 70% of those who received Keytruda alone. The combination also lowered the risk of distant metastasis or death by 38%. The companies say early evidence suggests patients on intismeran may also live longer overall, though that will take years to confirm.
How the trial worked
The double-blinded, randomized study enrolled 1,137 patients with high-risk melanoma, stages 2B to 4, that was likely to return. All had surgery to remove visible disease first. They were then assigned to Keytruda alone or to Keytruda plus up to nine doses of intismeran, given every three weeks. Two-thirds of participants received the combination.
The vaccine is tailored to each patient's tumor and trains the immune system to recognize up to 34 neoantigens, the distinct proteins produced by mutating cancer cells. No new safety signals appeared. Most treatment-related side effects are likely to stem from Keytruda, which commonly causes fatigue and muscle pain and can occasionally cause severe liver or lung inflammation.
The companies reportedly released the data early after a third party apparently broke the embargo. The results will be published in the New England Journal of Medicine and presented at a cancer conference this weekend. Investors responded coolly, and both stocks initially fell.
What comes next
Trial participant Beth Ryzyk, diagnosed with stage 3C melanoma in 2023, said at a Memorial Sloan Kettering press conference that she sometimes forgets about the cancer. She and her doctors remain blinded to her treatment group.
Michael Postow of Memorial Sloan Kettering said the hope is that the principle extends to other cancers, particularly those with a lower tumor mutation burden. Merck and Moderna are already running late-stage trials of intismeran plus immunotherapy in other tumor types, including non-small cell lung cancer.
Approval would make intismeran a leading next-generation cancer vaccine and would bolster mRNA technology, which has faced criticism from vaccine opponents, including U.S. Health Secretary Robert F. Kennedy Jr.
