mRNA Vaccine Reduces Risk of Melanoma Recurrence or Death

New clinical trial results show a personalized mRNA-based melanoma vaccine, intismeran, significantly reduces the risk of cancer recurrence or death within two years. The vaccine, the first individualized cancer vaccine to show positive results in a Phase III clinical trial, is custom-made to target genetic mutations unique to an individual’s melanoma. 

The Australian-led study that was conducted across 157 sites worldwide included 1,137 patients whose melanoma had been surgically removed but were at high risk of it returning. All were treated with an immunotherapy drug called pembrolizumab for 12 months, and some were also given the personalized intismeran vaccine. Patients had not previously received any cancer drug treatment. Findings showed at two years post-treatment, the combination of intismeran and pembrolizumab reduced the risk of melanoma recurrence or death by 42 percent compared to treatment with pembrolizumab alone. In patients receiving the combination of intismeran and pembrolizumab, 82 percent were alive and recurrence-free after two years, compared with 70 percent of participants treated with pembrolizumab alone.

Jessamy Tiffen, PhD, acting deputy director of the Centre for Cancer Innovations at the Centenary Institute, who was not involved in the research, said what was “truly remarkable” about the vaccine was the “deeply personalized nature of the treatment, something cancer researchers have been striving to achieve for decades. Where previously oncologists could pick a targeted therapy based on a single gene mutation present in the melanoma, this bespoke mRNA vaccine targets up to 34 gene mutations, unique to each patient. This vaccine, in combination with another type of immunotherapy, then trains the immune system to recognize and eliminate the melanoma, and most importantly, stop it from coming back.”

Dr. Tiffen noted that the treatment, if progressed, would not benefit all people with melanoma: “A significant portion do not respond to the vaccine in the first instance. Cancer cells also have an insidious ability to adapt and evade whatever treatment we throw at them. Only time will tell how effective the treatment is beyond two years, but the results are clear that the combination works better than immunotherapy alone, and that’s a very exciting development.”

The drug manufacturers said it was too early to tell from the data whether the combination treatment improved long-term survival.