Moderna and Merck's experimental vaccine Intismeran, combined with Keytruda, slashes the risk of death and melanoma returning by 49 percent, according to Phase 3 trial results.
Interim data released on Wednesday shows that the treatment met both of its main clinical trial goals by reducing cancer recurrence and preventing tumors from spreading to other parts of the body. The study marks the first positive late-stage trial for a messenger RNA cancer vaccine and the first to show that adding the shot to Keytruda works better than immunotherapy alone.
Phase 3 of the study involved 1,137 high-risk patients diagnosed with stage IIB to IV melanoma whose tumors had been surgically removed. Melanoma is the deadliest form of skin cancer, originating in pigment-producing cells known as melanocytes.
Phase 3 trial details
Trial volunteers were randomized to receive either Keytruda alone or Keytruda in combination with up to nine doses of the personalized vaccine for about one year. The pharmaceutical companies reported that no new safety signals have emerged during the study, which evaluates late-stage clinical safety and efficacy prior to regulatory submission.
The interim findings released on Wednesday build upon positive data gathered from Phase 2 trials of the same combination treatment regimen earlier this year. Keytruda, manufactured by American pharmaceutical company Merck, is an established immunotherapy drug designed to help the body's immune system detect and attack tumor cells.
Speaking on CNBC's Squawk Box alongside Merck Research and Development head Dean Li, Moderna Chief Executive Stephane Bancel hailed the clinical results. "It's a big moment for medicine, a big moment for patients," Bancel said during the broadcast.
Bancel noted that Moderna and Merck have not yet decided on pricing for Intismeran because the trial data only became available "a couple days ago." He explained that unlike certain personalized cell therapies, the treatment does not use patients' own living cells, which could allow manufacturing to scale more easily and help lower costs.
How the mRNA cancer vaccine works
Intismeran utilizes messenger RNA technology, a platform pioneered by Massachusetts-based biotechnology firm Moderna during the development of Covid vaccines. Messenger RNA, or mRNA, acts as a genetic blueprint that instructs human cells to manufacture specific proteins.
The manufacturing process begins by extracting DNA snippets from a patient's surgically removed tumor. Scientists insert these specific genetic sequences into mRNA molecules, creating a custom shot where no two doses are identical for different individuals.
Administered post-surgery, the personalized vaccine delivers genetic instructions into human cells to train the immune system to recognize cancer cells. The goal is to prompt the immune system to identify and destroy recurring cancer cells before they can multiply and form new tumors.
Data from the earlier Phase 2 trial indicated that side effects from the vaccine included fatigue, followed by injection site pain and chills.
Melanoma impact and patient results
Melanoma represents the most serious form of skin cancer. More than 1 million Americans are currently living with melanoma, with roughly 4 percent affected by advanced forms of the disease.
Among the participants in the Phase 2 trial was Gary Keblish, a 61-year-old teacher from Brooklyn, New York, who was diagnosed with late-stage melanoma in 2019. The cancer was initially detected in a dark-brown mole on his back that he had possessed for as long as he could remember.
Keblish previously told NBC News that he initially "felt numb" upon receiving his cancer diagnosis. He subsequently enrolled in the clinical trial testing the experimental vaccine to prevent tumor recurrence, received the combination treatment, and has remained cancer-free for two years.
Future clinical trials and regulatory plans
The Phase 3 study will continue tracking overall patient survival alongside other key secondary outcomes. Moderna and Merck plan to present the full trial findings at an upcoming international medical meeting, though the companies have not specified when they will apply for approval from US regulatory authorities.
In addition to melanoma, the two drugmakers are currently testing the experimental mRNA vaccine across several other tumor types, including bladder cancer, kidney cancer, and non-small cell lung cancer.
