Merck and Moderna report 42% lower melanoma recurrence risk with personalised mRNA therapy

Merck and Moderna have reported that their investigational personalised mRNA cancer therapy, intismeran autogene, combined with KEYTRUDA (pembrolizumab), reduced the risk of melanoma recurrence or death by 42% compared with KEYTRUDA alone in a Phase 3 clinical trial.

The results from the INTerpath-001 study cover patients with completely resected stage IIB-IV cutaneous melanoma, a form of skin cancer. The companies reported a hazard ratio of 0.58 for recurrence-free survival, with a 95% confidence interval of 0.45–0.75 and a p-value below 0.001. The findings were announced on 22 October 2026 ahead of presentation at the European Society for Medical Oncology (ESMO) Congress 2026.

The combination also reduced the risk of distant metastasis or death by 38% compared with KEYTRUDA alone, with a hazard ratio of 0.62. The results provide further Phase 3 evidence for an individualised neoantigen therapy designed around the mutations found in each patient’s tumour.

The treatment remains investigational. Overall survival data are not yet mature, and the companies said the study will continue to assess this and other endpoints. Merck and Moderna are engaging with regulatory authorities following the results.

INTerpath-001 reports improvements in recurrence-free survival

The global, randomised, double-blind Phase 3 INTerpath-001 trial enrolled 1,137 patients with high-risk melanoma following complete surgical resection. Participants were assigned in a 2:1 ratio to receive intismeran plus KEYTRUDA or placebo plus KEYTRUDA.

After a median follow-up of 24.6 months, the two-year recurrence-free survival rate was 82.2% among patients receiving the combination, compared with 70.0% in the KEYTRUDA-only group.

Recurrence-free survival measures the period patients remain alive without their cancer returning. The trial’s primary endpoint included recurrence at local, regional or distant sites, or death from any cause.

The two-year distant metastasis-free survival rate was 88.5% for the combination group and 80.2% for the control group. This endpoint assesses the period patients remain alive without cancer spreading to distant parts of the body.

The companies reported statistically significant improvements in both endpoints. Median recurrence-free survival and median distant metastasis-free survival had not been reached in either treatment group at the reported analysis.

These findings suggest that adding the individualised therapy can improve outcomes measured by recurrence and distant spread in the studied population. They do not yet establish whether the combination improves overall survival.

How the personalised mRNA cancer therapy works

Intismeran autogene, also known as V940 or mRNA-4157, is an investigational individualised neoantigen therapy jointly developed by Merck and Moderna.

Unlike a vaccine designed to target the same antigens in every recipient, the treatment is developed using information from an individual patient’s tumour. Tumour and normal DNA information is used to identify selected mutations and design an mRNA treatment encoding up to 34 neoantigens associated with that patient’s cancer.

After administration, the encoded sequences are translated in the body and presented to the immune system. The objective is to stimulate a targeted T-cell response against cancer cells carrying the relevant tumour-associated mutations.

The treatment is being evaluated alongside KEYTRUDA, Merck’s anti-PD-1 immunotherapy. Pembrolizumab helps the immune system recognise and attack cancer cells by blocking the PD-1 pathway, which can otherwise limit immune activity.

The combination is intended to pair a personalised immune response directed at tumour-specific targets with an established immunotherapy approach. Its clinical value must be assessed through controlled trials rather than the proposed mechanism alone.

Results show a delayed treatment benefit

The reported analysis found that the improvement in recurrence-related outcomes was not apparent during the first six months of treatment.

During that period, the hazard ratio for recurrence or death was 0.99, while the hazard ratio for distant metastasis or death was 1.01. Both estimates were broadly consistent with comparable risks between the treatment groups during the initial period.

In a pre-specified sensitivity analysis examining outcomes after six months, the combination was associated with a 58% lower risk of recurrence or death and a 50% lower risk of distant metastasis or death compared with KEYTRUDA alone.

A separate sensitivity analysis of the modified intention-to-treat population reported a 49% reduction in recurrence or death risk and a 45% reduction in distant metastasis or death risk.

These analyses provide additional detail on the timing and consistency of the reported effects. However, the six-month findings come from a specified sensitivity analysis and should not be interpreted as proof that every patient will experience a delayed benefit.

Safety and ongoing clinical evaluation

The companies reported that the safety profile of intismeran combined with KEYTRUDA was generally consistent with previous studies of the combination, with no new safety signals identified.

Treatment-related adverse events occurred in 95.8% of patients in the combination group, compared with 90.0% of patients receiving KEYTRUDA alone. Grade 3–5 treatment-related adverse events were reported in 14.2% and 13.4% of patients, respectively.

The most common reported adverse events in the combination group were fever, also known as pyrexia, at 52.2%; injection-site pain at 51.0%; and fatigue at 38.5%.

The results highlight the importance of assessing the incremental benefit of the personalised treatment alongside its additional adverse events, treatment burden and practical requirements. The full clinical assessment will also need to account for longer-term safety and patient-reported outcomes.

Merck and Moderna expand the clinical development programme

INTerpath-001 builds on earlier Phase 2b research evaluating intismeran with KEYTRUDA in patients with resected melanoma. The companies are also studying the approach in other cancer types and treatment settings.

According to the announcement, the wider INTerpath programme includes nine Phase 2 and Phase 3 trials, including three ongoing Phase 3 studies in non-small cell lung cancer. Additional research is examining potential applications in pancreatic, gastric and other cancers.

The breadth of the programme reflects an effort to determine whether personalised neoantigen therapies can be applied beyond a single tumour type. Results in melanoma cannot, however, establish effectiveness in other cancers, where tumour biology and treatment responses may differ.

For the companies, the latest findings provide further evidence to support discussions with regulators and continued clinical development. Regulatory decisions, manufacturing capacity, individualised production timelines, reimbursement and treatment costs will be important considerations if the therapy advances towards commercial use.

Regulatory decisions and overall survival remain key milestones

The INTerpath-001 results strengthen the evidence for combining an individualised mRNA therapy with checkpoint inhibition in high-risk resected melanoma. The absolute difference in two-year recurrence-free survival was 12.2 percentage points, while the difference in distant metastasis-free survival was 8.3 percentage points.

Those measures offer additional context alongside the relative risk reductions reported by the companies. They should not be confused with proof of a survival advantage, which remains under evaluation.

The next important developments will include the full presentation of the trial findings, further follow-up on overall survival and other endpoints, and regulatory review.

For the pharmaceutical industry, the study is a significant clinical milestone for personalised cancer immunotherapy. Whether the approach becomes a widely used treatment option will depend on the totality of clinical evidence, regulatory decisi

Follow B2B Market Signal on social media for the latest business news, industry developments, market intelligence and analysis. Connect with us on LinkedIn and follow us on Instagram at @b2bmarketsignal for regular updates.