A personalized mRNA cancer vaccine has shown promising results in a late-stage clinical trial, helping patients with high-risk melanoma remain cancer-free for longer after surgery.
The vaccine, known as intismeran, was developed using genetic information from each patient’s own tumour. When combined with the immunotherapy drug Keytruda, it reduced the risk of melanoma returning compared with Keytruda alone.
The Phase 3 trial involved more than 1,000 patients with stage 2, 3 or 4 melanoma. Participants were randomly assigned to receive either the personalized vaccine alongside Keytruda or Keytruda alone for approximately one year.
Patients receiving the combination remained cancer-free for longer and were less likely to experience the cancer spreading to other organs. Researchers say the results represent an important milestone for personalized cancer vaccines.
However, detailed findings from the trial have not yet been published or peer reviewed. The companies developing the treatment, Moderna and Merck & Co., have so far released preliminary results, meaning questions remain about the long-term effectiveness of the vaccine.
The treatment works by identifying mutations in an individual patient’s tumour. These mutations can produce proteins called neo antigens, which can help the immune system recognize cancer cells. The personalized vaccine uses mRNA to instruct the immune system to target these specific markers.
Keytruda works alongside the vaccine by blocking a signal that cancer cells use to suppress immune responses, allowing immune cells to remain active against the tumour.
The latest findings build on earlier research involving the same vaccine and immunotherapy combination. A mid-stage study involving 157 melanoma patients previously found that the combination reduced the risk of recurrence by about half compared with Keytruda alone.
Researchers are also investigating personalized mRNA vaccines for other difficult-to-treat cancers. In an early-stage pancreatic cancer study, several patients developed long-lasting immune responses after receiving a personalized vaccine alongside chemotherapy and immunotherapy.
The melanoma results do not yet mean that a personalized cancer vaccine is widely available as a standard treatment. Further analysis and peer-reviewed publication will be needed to establish how durable the benefits are and how the approach could be used across different cancers.
Nevertheless, the findings represent a significant development in cancer immunotherapy and suggest that mRNA technology could eventually enable treatments tailored to the genetic characteristics of an individual patient’s tumour.
