Five years. In the brutal world of Stage III/IV melanoma — a cancer where the five-year survival rate was below 20 percent just fifteen years ago — five years of sustained, meaningful reduction in the risk of recurrence and death represents an outcome that was not achievable in the recent past. At the American Society of Clinical Oncology Annual Meeting in Chicago on June 3, 2026, and simultaneously published in the Journal of Clinical Oncology, researchers presented the five-year update from the KEYNOTE-942 Phase 2b trial of intismeran autogene (mRNA-4157/V940) combined with Keytruda (pembrolizumab). The results have prompted some of the most effusive responses ever heard at an oncology conference.
After a median 60.3 months of follow-up, patients who received the combination of intismeran autogene and Keytruda had a 49 percent lower risk of melanoma recurrence or death compared to those who received Keytruda alone. This 49 percent reduction is precisely identical to the three-year result reported in 2024 — a finding of remarkable significance. When a treatment effect maintains its magnitude unchanged from year 3 to year 5 in an oncology trial, it suggests that the immune system changes induced by the treatment are durable and potentially permanent, rather than fading as time passes.
The clinical numbers are equally striking. At 5 years: 68.8 percent of patients in the combination arm remained cancer-free versus 49.1 percent of patients receiving Keytruda alone. The vaccine's impact on the most feared outcome in melanoma — distant metastasis, the spread of cancer to organs throughout the body that defines Stage IV disease — was even more profound: the risk of distant metastasis or death was reduced by 59 percent in the vaccine group. And in an exploratory overall survival analysis, the combination produced a 53 percent improvement in overall survival — a directional signal that will need Phase 3 confirmation but that has energized the field.
"This study confirms that intismeran plus pembrolizumab demonstrates a durable benefit over pembrolizumab alone in resected high-risk melanoma," said study presenter Dr. Matteo Carlino of the University of Sydney at ASCO.
How Intismeran Autogene Is Made and How It Works
What makes intismeran autogene different from any vaccine ever made is its individualization. Every dose is built from scratch for a single patient. After surgical removal of a melanoma tumor, the tumor's DNA is sequenced. Bioinformatics algorithms identify up to 34 neoantigens — protein fragments present on the tumor's surface that mark it as "foreign" to the immune system. Those neoantigen sequences are then encoded into a synthetic mRNA strand and manufactured as an injectable vaccine customized specifically for that patient.
When the patient receives an injection, their immune system learns to recognize those specific neoantigens. When Keytruda (a PD-1 checkpoint inhibitor) is added to the regimen, it releases the immune system's natural brakes, allowing the trained T cells to attack any remaining microscopic melanoma cells with full force. The combination functions as both a targeting system and an accelerator for the immune attack.
Each dose is custom-manufactured by sequencing a patient's unique tumor to identify up to 34 neoantigens, which are then encoded into a synthetic mRNA strand. This is not mass production — it is bespoke medicine at the molecular level. Analysts from William Blair noted that the stability of the treatment effect from year 3 to year 5 "suggests the personalized vaccine successfully reprograms the adaptive immune system for long-term surveillance."
What This Means for the Pipeline and Future Cancer Treatment
Moderna and Merck now have eight Phase 2 and Phase 3 clinical trials underway across multiple tumor types — including melanoma (Phase 3 pivotal trial now enrolling), non-small cell lung cancer, bladder cancer, renal cell carcinoma, and cutaneous squamous cell carcinoma. The pivotal Phase 3 melanoma trial results are expected in 2026–2027 and will determine whether intismeran receives FDA approval, potentially entering the market in 2027. If the Phase 3 results confirm the Phase 2 findings, this could become standard of care for resected high-risk melanoma.
Frequently Asked Questions
Q: What were the 5-year results for intismeran autogene at ASCO 2026?
A: 49% reduction in risk of recurrence or death vs Keytruda alone (maintained from year 3). 59% reduction in distant metastasis or death. 53% improvement in overall survival (exploratory). 68.8% of combination patients cancer-free at 5 years vs 49.1% on Keytruda alone.
Q: What makes intismeran autogene different from other cancer treatments?
A: It is a fully personalized mRNA vaccine custom-made for each individual patient, encoding up to 34 neoantigens unique to that patient's tumor. No two doses are identical.
Q: Is intismeran autogene FDA-approved?
A: Not yet. Phase 3 pivotal trials are enrolling. FDA approval is expected in 2027 if Phase 3 results confirm Phase 2 findings. This remains an investigational therapy outside of clinical trials.
Q: What type of melanoma does this vaccine target?
A: Resected high-risk Stage III/IV melanoma — patients who have had surgery to remove their melanoma but face high risk of recurrence.
Q: What other cancers is intismeran being studied in?
A: Non-small cell lung cancer, bladder cancer, renal cell carcinoma, and cutaneous squamous cell carcinoma are among the eight ongoing Phase 2 and Phase 3 trials.
