An experimental mRNA vaccine cut the risk of melanoma recurrence or death by 42% in a large clinical trial, according to results first reported by KOLD 13 News. The finding carries particular weight in Arizona, where melanoma rates run 40% above the national average.

"I'd say it's really way too common," Andrew Saal of the Pima County Health Department told KOLD, speaking about melanoma in the region.

The vaccine, called intismeran autogene, was developed jointly by Moderna and Merck. In the Phase 3 INTerpath-001 trial, the vaccine combined with the immunotherapy drug pembrolizumab (sold as Keytruda) reduced the risk of recurrence or death by 42% compared with Keytruda alone, according to the American Journal of Managed Care. Keytruda is already an established post-surgery treatment for high-risk melanoma, so the vaccine's benefit came on top of existing therapy.

The trial enrolled 1,137 patients with completely resected stage IIB-IV melanoma. After a median follow-up of about two years, 82.2% of patients who received the combination remained recurrence-free, compared with 70% of those on Keytruda alone, according to the companies' detailed results.

The vaccine is personalized. Each dose is produced from a patient's own tumor sample and contains synthetic mRNA coding for up to 34 markers unique to that patient's cancer, according to the companies.

Not yet approved

The vaccine has not received FDA approval. Saal told KOLD the trial results still need independent review.

"Right now it's just the manufacturers announcing this trial. The actual trial itself should be published in the next few months in the New England Journal," Saal said. "We are eagerly looking forward to this to make certain that it was designed well and the outcomes are what they say they should be."

Merck and Moderna said they are "engaging with regulatory authorities," according to the companies' statement. STAT News reported in October that the companies are preparing to file the vaccine for approval.

Saal called the vaccine a potential "game changer" for the region.

Arizona's melanoma burden

Arizona's melanoma rates are 40% higher than the U.S. average, according to the most recent data from the American Cancer Society, as reported by KOLD. Melanoma incidence in the state has been rising for about two decades.

Candice Mason, a Tucson-area melanoma survivor interviewed by KOLD, was diagnosed with stage one melanoma in 2017. The cancer progressed to stage three after it was found in her lymph nodes, and she was diagnosed again in 2019.

"The melanoma that started on the side of my nose spread to my brain, lungs, spleen and pelvic wall," Mason told KOLD. She underwent brain surgery, dual immunotherapy and multiple rounds of radiation. She is in remission.

"I don't really think that remission is, you know, 100 percent ever," Mason said. "It's always in the back of your mind, you never know if it's gonna come back."

A treatment, not prevention

The vaccine is a treatment for patients who have already had melanoma surgically removed. It is not a preventive measure. Both Saal and Mason told KOLD that sunscreen, shade and regular skin checks remain the best protection against skin cancer.

Overall survival data from the trial are not yet mature, though the companies reported a favorable trend.