An experimental mRNA vaccine developed by Moderna in partnership with Merck has demonstrated a significant reduction in the risk of melanoma returning or death when used in combination with Merck's immunotherapy drug Keytruda. The investigational vaccine, known as Intisemran, met its primary endpoints in a Phase 3 clinical trial, according to interim results released by the companies.
The trial showed that the combination therapy slashed the risk of melanoma recurrence or death by 49% compared to Keytruda alone. This marks the first positive late-stage trial for an mRNA cancer vaccine and the first to show superior efficacy when an mRNA vaccine is added to an existing immunotherapy treatment.
The Phase 3 trial involved 1,137 high-risk patients with stage IIB-IV melanoma that had been surgically removed. Participants were randomly assigned to receive up to nine doses of Keytruda along with the personalized vaccine or Keytruda alone for approximately one year. The companies reported that no new safety concerns emerged during the trial.
Intisemran utilizes mRNA technology, similar to that used in COVID-19 vaccines. It is designed to teach the body's immune system to recognize and attack cancer cells. The vaccine is personalized, using genetic material from a patient's tumor to create a vaccine tailored specifically to them. After surgery, the vaccine is administered to help prevent the cancer from returning by enabling the body to identify and destroy cancer cells before they can multiply.
Side effects observed in Phase 2 trials included fatigue, injection site pain, and chills. Moderna CEO Stephane Bancel stated that pricing for the treatment has not yet been determined, as the data is very recent. He noted that the manufacturing process for this vaccine, which does not use a patient's own cells, could potentially be scaled to reduce costs.
The companies are continuing to monitor overall survival and other outcomes in the Phase 3 study. Findings are expected to be presented at an upcoming international medical conference, though the timeline for seeking U.S. approval remains unclear. Beyond melanoma, Merck and Moderna are also investigating the vaccine's potential in treating other cancers, including bladder cancer, kidney cancer, and non-small cell lung cancer.
Melanoma is the most serious form of skin cancer, affecting over one million Americans, with approximately 4% of cases being advanced. The positive results from this trial offer a hopeful advancement in the treatment of high-risk melanoma patients.