Merck and Moderna's Individualized mRNA Cancer Vaccine Intismeran (V940) Achieves Historic Phase 3 Victory in Adjuvant Melanoma
On August 19, 2026, Merck and Moderna, Inc. announced positive topline results from the pivotal Phase 3 INTerpath-001 trial (NCT05933577) evaluating adjuvant treatment with intismeran autogene (V940 or mRNA-4157) in combination with Keytruda (pembrolizumab) in patients with completely resected Stage IIB-IV cutaneous melanoma.
This milestone represents the first successful Phase 3 readout for an individualized neoantigen therapy (INT) and the first for any mRNA-based cancer therapy. It is also the first Phase 3 trial to demonstrate a statistically significant and clinically meaningful improvement over standard-of-care immunotherapy alone (Keytruda monotherapy) in the adjuvant setting for resected melanoma.
Mechanism of Action: Tailored to the Patient's Tumor
Intismeran autogene is a potential first-in-class individualized neoantigen therapy designed and manufactured specifically for each patient. Using a tumor sample obtained during surgery, the patient's unique mutational signature ("fingerprint") is sequenced to design a synthetic mRNA coding for up to 34 patient-specific neoantigens encapsulated within a lipid nanoparticle. Once injected, the mRNA is translated to train the patient's immune system (specifically T-cells) to recognize and destroy residual cancer cells.
Key Efficacy and Safety Data from INTerpath-001
The trial enrolled 1,137 patients who were randomized 2:1 to receive either the combination (up to 9 doses of intismeran and 9 cycles of Keytruda) or Keytruda alone for approximately one year:
- Primary Endpoint Met: At a pre-specified interim analysis, the combination therapy demonstrated statistically significant and clinically meaningful improvements in Recurrence-Free Survival (RFS) compared to Keytruda alone in patients with high-risk completely resected cutaneous melanoma who had not received prior systemic therapy.
- Secondary Endpoint Met: The study also met its key secondary endpoint of Distant Metastasis-Free Survival (DMFS).
- Safety Profile: The combination showed a safety and tolerability profile consistent with prior Phase 2b results, with no new safety signals observed.
- Ongoing Follow-up: The trial continues in a double-blind fashion to evaluate other secondary endpoints, including Overall Survival (OS).
Building on Strong 5-Year Phase 2b Data
This Phase 3 success solidifies the long-term efficacy seen in the randomized Phase 2b KEYNOTE-942/mRNA-4157-P201 trial. Five-year follow-up data presented at the 2026 ASCO Annual Meeting demonstrated that adding intismeran to Keytruda led to:
- A 49% reduction in the risk of recurrence or death (HR=0.51; 95% CI, 0.294-0.887).
- A 59% reduction in the risk of distant metastasis or death (HR=0.411; 95% CI, 0.200-0.843) compared to Keytruda alone.
Executive and Investigator Reactions
Professor Georgina Long, principal investigator and medical director of Melanoma Institute Australia, highlighted the clinical impact:
"Today’s results represent a landmark moment for adjuvant melanoma treatment. This is the first Phase 3 study to show that intismeran, a treatment designed based on the unique mutational ‘fingerprint' of a patient's own tumor, given in combination with pembrolizumab can reduce the risk of recurrence or death in patients with completely resected stage IIB-IV melanoma compared to KEYTRUDA alone. Intismeran in combination with pembrolizumab has the potential to establish a new treatment paradigm in the adjuvant melanoma setting, helping patients remain cancer-free for longer."
Stéphane Bancel, CEO of Moderna, celebrated the realization of personalized medicine:
"These Phase 3 findings represent a pivotal moment for the field of cancer research. For many years, the idea of creating an mRNA treatment designed specifically for an individual patient's cancer was aspirational. We are now helping turn that vision into a reality."
Next Steps and Broad Development
Merck and Moderna plan to present the detailed INTerpath-001 data at an upcoming international medical meeting and intend to engage with global regulators to initiate marketing application submissions.
The companies are actively expanding the INTerpath clinical development program, which currently includes nine trials across multiple solid tumor types and stages, including non-small cell lung cancer (NSCLC), bladder cancer, renal cell carcinoma, and pancreatic ductal adenocarcinoma.