Archive · 20 Aug 2026
Merck and Moderna Vaccine Posts Positive Phase 3 Melanoma Results
Merck and Moderna tested a new vaccine for people with a serious type of skin cancer called melanoma.
The vaccine is made specially for each patient by studying changes in their tumor.
It is designed to help the immune system recognize and attack the cancer.
Patients also received Merck’s Keytruda medicine.
In a large Phase 3 study, the combination worked better than Keytruda alone at stopping the cancer from returning.
It also lowered the chance that the cancer would spread to other parts of the body.
The study will continue to see whether patients live longer overall.
The companies have not yet announced when they will ask regulators to approve the treatment.
Merck and Moderna’s personalised mRNA cancer vaccine met key goals in its first Phase 3 trial.
The trial involved more than 1,100 patients whose high-risk melanoma had been surgically removed.
Combined with Keytruda, the vaccine significantly extended the time patients lived without cancer returning.
The combination also reduced the risk of melanoma spreading to distant parts of the body.
The companies will continue monitoring overall survival and plan discussions with regulators in coming months.
- Who
- Merck and Moderna, which developed the personalised cancer vaccine, and more than 1,100 patients with surgically removed high-risk melanoma.
- What
- A Phase 3 trial found that the vaccine combined with Keytruda improved outcomes compared with Keytruda alone.
- When
- The positive Phase 3 results were reported on Wednesday; longer-term follow-up is continuing.
- Where
- The articles do not specify where the trial took place.
- Why
- The companies are evaluating a personalised treatment intended to help the immune system identify and attack each patient’s cancer.
- Treatment
- An mRNA-based personalised cancer vaccine used with Merck’s Keytruda immunotherapy.
- Cancer type
- High-risk melanoma.
- Trial phase
- Phase 3.
- Participants
- More than 1,100 patients whose melanoma was completely removed through surgery.
- Main result
- The combination significantly extended the time patients lived without their cancer returning compared with Keytruda alone.
- Additional result
- The treatment reduced the risk of melanoma spreading to distant parts of the body.
- Next steps
- The trial will assess overall survival, while the companies prepare to discuss the results with regulators.