Moderna mRNA-4359 Shows 83% Response Rate in First-Line Melanoma at AACR 2026

At the AACR Annual Meeting in San Diego (April 17–22, 2026), Moderna presented Phase 1/2 data on mRNA-4359, an mRNA-based cancer antigen therapy combined with pembrolizumab as first-line treatment for locally advanced or metastatic melanoma. Among 12 evaluable participants: overall response rate (ORR) was 83% (95% CI: 52%–98%), disease control rate was 92%, and 2 complete responses and 8 partial responses were observed. Median time to response was 6 weeks. All 7 evaluable patients showed antigen-specific T-cell responses by immunoassay. PD-L1-positive tumors (TPS≥1%) achieved 88% ORR; PD-L1-negative tumors showed 67% ORR, suggesting activity beyond checkpoint-sensitive subsets. The FDA had previously granted Fast Track designation for this combination in checkpoint-inhibitor-refractory metastatic melanoma. mRNA-4359 encodes specific tumor-associated antigens to prime the immune system in combination with checkpoint blockade.