Moderna and Merck (MSD) are evaluating the individualized neoantigen therapy mRNA-4157 (V940) with the PD-1 checkpoint inhibitor Keytruda (pembrolizumab). The program includes the Phase 3 INTerpath-001 trial in resected high-risk melanoma.

Unlike preventive vaccines against pathogens, V940 is therapeutic and individualized. It encodes selected tumor neoantigens with the aim of directing the patient's T cells toward cells carrying those mutations.

🧬 Illustrative overview of the proposed combination
Simplified illustration; not a patient-level simulation
Current Stage
Stage 1 of 4
Illustrated target state
Not selected
Illustrated T-cell state
No response shown
PD-1 pathway illustration
Shown active
Outcome
Not simulated
🔬 Illustration note

This graphic is a simplified teaching aid. It does not model an individual tumor, immune response, treatment effect, or clinical outcome.

1. Preventive and therapeutic cancer vaccines

Preventive vaccines against cancer-causing infections and individualized therapeutic vaccines address different targets:

  • Preventive vaccines: Some vaccines reduce cancer risk by preventing infection with cancer-associated viruses, such as HPV or hepatitis B.
  • Individualized therapeutic vaccines: V940 is designed from selected mutations found in a patient's tumor and is being studied after cancer has been diagnosed.
Modality Mechanism Analogy
mRNA Vaccine (V940) Encodes up to 34 patient-specific neoantigens and is intended to elicit neoantigen-specific T-cell responses. Supplies selected tumor-specific antigen targets.
CAR-T Cell Therapy Extracts patient T-cells, edits chimeric antigen receptors ex-vivo, re-infuses. Engineers receptors on extracted T cells before reinfusion.
PD-1 Blockade (Keytruda) Blocks PD-1, an inhibitory receptor on activated T cells. Blocks inhibitory PD-1 signaling.

2. How mRNA-4157 (V940) is made

Sponsor descriptions and the published Phase 2b paper describe the process at a high level:

  1. Tumor analysis: A tumor sample is sequenced to identify mutations that may yield neoantigens.
  2. Candidate selection: An algorithm selects up to 34 patient-specific neoantigens for the investigational product.
  3. Manufacture and dosing: The selected sequences are encoded in synthetic mRNA and delivered by intramuscular injection.
  4. Intended immune response: Translation and antigen presentation are intended to generate or expand T-cell responses against the selected neoantigens. This is a proposed mechanism, not a guarantee of response in an individual patient.

3. Combining V940 with Keytruda

The PD-1 / PD-L1 immune checkpoint pathway can suppress T-cell activity. PD-L1 expression varies within and between tumors, so the illustration should not be read as showing every cancer cell expressing PD-L1 or every T cell being switched off.

The combination is intended to address both antigen recognition and checkpoint suppression:

  • V940: Aims to prime and expand lymphocytes directed at selected neoantigens.
  • Keytruda (pembrolizumab): Blocks PD-1 engagement, reducing one inhibitory signal on T cells.

4. Clinical evidence and the Phase 3 program

The note's reported figures come from the KEYNOTE-942 Phase 2b follow-up. Phase 3 enrollment and endpoints should be kept separate from those earlier efficacy estimates:

  • KEYNOTE-942 (Phase 2b):
    • The reported recurrence-free-survival hazard ratio was 0.51, described as a 49% reduction in the risk of recurrence or death for V940 plus pembrolizumab compared with pembrolizumab alone.
  • INTerpath-001 (Phase 3):
    • The larger trial should be assessed on its own endpoints and results. The Phase 2 estimate should not be described as Phase 3 success.

5. Open constraints

Individualized manufacturing and tumor evolution create practical and biological constraints:

  1. Turnaround time: Sequencing, candidate ranking, and custom manufacturing add time between tissue collection and dosing. This note does not claim a fixed interval.
  2. Manufacturing and cost: V940 is made for one patient at a time. Scaling this process while controlling cost remains a manufacturing problem.
  3. Antigen escape and clonal evolution: Tumor subclones may lose or downregulate targeted neoantigens. Whether later formulations can or should be updated using liquid-biopsy data remains a research question.

Primary references