Merck and Moderna report Phase 3 melanoma trial results

Merck (NYSE: MRK) and Moderna (NASDAQ: MRNA) announced results from the Phase 3 INTerpath-001 trial evaluating intismeran autogene in combination with KEYTRUDA (pembrolizumab) as adjuvant treatment for patients with completely resected stage IIB-IV melanoma. The results were presented at the European Society for Medical Oncology (ESMO) Congress 2026 and accepted for publication in The New England Journal of Medicine.

The trial enrolled 1,137 patients randomized 2:1 to receive intismeran plus KEYTRUDA or placebo plus KEYTRUDA. At the primary pre-specified analysis, after a median follow-up of 24.6 months, intismeran combined with KEYTRUDA reduced the risk of recurrence or death by 42% (HR=0.58 [95% CI, 0.45–0.75]; p<0.001) compared to KEYTRUDA alone. The combination also reduced the risk of distant metastasis or death by 38% (HR=0.62 [95% CI, 0.45–0.85]; p=0.002).

The two-year recurrence-free survival rate was 82.2% for the combination arm versus 70.0% for KEYTRUDA alone. The two-year distant metastasis-free survival rate was 88.5% versus 80.2%, respectively. Overall survival data remain immature, though a favorable trend was noted.

A pre-specified sensitivity analysis showed that after six months, following the intismeran immunization regimen, the combination reduced the risk of recurrence or death by 58% (HR=0.42 [95% CI, 0.30–0.58]) compared to KEYTRUDA alone. During the first six months, efficacy was comparable between arms.

Treatment-related adverse events occurred in 95.8% of patients receiving the combination and 90.0% receiving KEYTRUDA alone. Grade 3–5 adverse events occurred in 14.2% and 13.4% of patients, respectively. The most common adverse events in the combination arm were pyrexia (52.2%), injection site pain (51.0%), and fatigue (38.5%). No new safety signals were observed.

The companies stated they are engaging with regulatory authorities based on these data. Merck and Moderna are also advancing nine Phase 2 and Phase 3 clinical trials across multiple tumor types through their INTerpath clinical development program, including three ongoing Phase 3 trials in non-small cell lung cancer.

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