Miami, Florida, USA, A new update from Moderna and Merck is bringing encouraging news for people living with high-risk melanoma.
At the 2026 ASCO Annual Meeting, the companies shared five-year results from their Phase 2b KEYNOTE-942 study. The findings show that a personalized cancer vaccine called intismeran autogene, when used with KEYTRUDA, continued to help patients stay cancer-free for longer after surgery.
Melanoma is one of the most serious forms of skin cancer. Even after successful surgery, many patients with Stage III or Stage IV melanoma face a high risk of the disease returning. That is why researchers have been looking for better ways to prevent recurrence and improve long-term outcomes.
The latest data followed patients for a median of 60.3 months, or about five years.
Researchers found that patients who received intismeran autogene along with KEYTRUDA had a 49% lower risk of cancer recurrence or death compared with patients who received KEYTRUDA alone. The combination treatment also reduced the risk of distant metastasis or death by 59%.
Distant metastasis happens when cancer spreads to other organs or parts of the body, making treatment more difficult.
Researchers also observed a positive trend in overall survival.
Although the survival analysis is still exploratory and requires more follow-up, patients receiving the combination therapy showed better survival outcomes than those receiving KEYTRUDA alone. One reason these results are attracting attention is the personalized nature of the treatment.
Unlike traditional therapies, intismeran autogene is designed individually for each patient. Scientists analyze the genetic mutations inside a patient's tumor and create an mRNA-based vaccine specifically targeted to those mutations.
The goal is to help the immune system recognize cancer cells more effectively and destroy them before they can grow again. Additional data presented at ASCO showed that patients receiving the combination therapy developed stronger immune responses. Researchers observed greater expansion of cancer-fighting T-cells and the emergence of new T-cell populations that were linked to the vaccine's targeted tumor mutations.
Patients who remained free from recurrence generally showed stronger immune responses than those whose cancer returned.
The treatment's safety profile remained consistent with earlier reports.
The most common side effects were fatigue, injection-site pain, and chills. Most side effects were mild to moderate, and no new safety concerns were identified during the five-year follow-up period. The findings add to growing evidence that personalized mRNA-based cancer treatments may play an important role in future cancer care.
For patients with high-risk melanoma, the ability to reduce the chance of recurrence for several years after surgery could represent a meaningful advance in treatment.
Moderna and Merck are continuing to evaluate intismeran autogene in several ongoing Phase 2 and Phase 3 studies across different cancers, including lung cancer, bladder cancer vaccine, kidney cancer, and melanoma.
As more data become available, researchers hope these personalized therapies can help deliver longer-lasting protection and better outcomes for cancer patients around the world.
About Merck
Merck, known as MSD outside the United States and Canada, is a global biopharmaceutical company focused on improving lives through science. With more than 130 years of experience, the company develops innovative medicines and vaccines for people and animals to help prevent and treat diseases worldwide.
About Moderna
Moderna is a biotechnology company and a leader in mRNA medicine. Its innovative platform supports the development of vaccines and treatments for infectious diseases, cancer, rare diseases, and other health conditions, with a mission to improve lives through advanced science.