With meteorological summer now officially underway, the heat rising and millions of Americans heading outdoors for longer days in the sun, new research offers encouraging news in the fight against melanoma, the deadliest form of skin cancer.

Researchers from NYU's Langone Perlmutter Cancer Center have announced significant progress in preventing melanoma recurrence, with a new treatment approach reducing the risk of the deadly skin cancer returning by nearly 50% over five years. The results were presented Monday at the American Society of Clinical Oncology's annual meeting and published in the Journal of Clinical Oncology.

The experimental treatment combines Moderna and Merck’s personalized mRNA vaccine, called intismeran autogene, with Merck's established cancer drug Keytruda. In a clinical trial involving 157 patients with advanced melanoma, those receiving both treatments fared substantially better than those receiving standard care alone.

After five years, approximately 69% of patients who received the vaccine combination remained cancer-free, compared to just 49% of those treated with Keytruda alone. The combination also reduced the risk of cancer spreading to other parts of the body by 59%.

How the treatment works

The personalized vaccine is created using genetic material from each patient's specific tumor. Scientists identify unique proteins called neoantigens that appear on cancer cell surfaces, then design a vaccine to train the immune system's T-cells to recognize and attack these targets. Each patient receives up to nine vaccine doses over several months, coordinated with their immunotherapy treatments. The personalized vaccines typically take four to six weeks to develop after surgery.

Promising safety profile

Unlike many cancer treatments that can cause severe side effects, the vaccine showed low toxicity. Patients reported flu-like symptoms similar to COVID vaccines, including chills and headaches, that lasted only a few days.

Next steps

The results come from a smaller trial, with researchers now analyzing data from a larger Phase 3 study involving 1,000 patients across multiple countries. If those results prove equally promising, experts say the approach could revolutionize cancer treatment.

“We have tried to use vaccines in cancer therapy for decades, but the efficacy has not been clinically relevant in phase 3 trials to date. If this is successful, this will open up a new field that will be relevant not just to melanoma, but many other cancers,” Dr. Shailender Bhatia of Fred Hutch Cancer Center, who was not involved in the research, told NBC News.

Melanoma affects about 112,000 Americans annually, and remains the most deadly form of skin cancer, with about half of patients experiencing recurrence within five years of initial treatment.

While this breakthrough offers hope for treatment, health officials continue to emphasize that prevention remains key; particularly during summer months, when UV exposure peaks. The American Cancer Society recommends using broad-spectrum sunscreen, seeking shade during peak hours, and wearing protective clothing when spending extended time outdoors.