Scientists built a melanoma vaccine from each patient’s own tumour, and it cut recurrence risk by 42%
A personalised mRNA melanoma vaccine used each patient’s own tumour data and lowered recurrence or death risk by 42% in a phase 3 trial.
A melanoma treatment that is made separately for each patient has cleared a major test. In a phase 3 trial, adding the personalised mRNA vaccine to standard immunotherapy lowered the risk of the cancer coming back, or causing death, compared with immunotherapy alone.
What changed for melanoma patients in the trial
The vaccine, called intismeran autogene, was tested in 1,137 patients with high risk melanoma whose tumours had been completely removed with surgery. These were patients with stage IIB through stage IV disease, including people with deeper tumours, cancer in nearby lymph nodes, and some whose distant spread had been removed by surgeons.
Researchers found that combining the vaccine with pembrolizumab, sold as Keytruda, reduced the risk of recurrence or death by 42 percent compared with pembrolizumab on its own. After two years, 82.2 percent of patients on the combination were alive without recurrence, versus 70 percent of those who got the standard treatment plus a placebo.
The benefit also showed up in spread to distant parts of the body. At the two year mark, 88.5 percent of patients given the combination were alive without distant spread, compared with 80.2 percent in the immunotherapy only group.
The effect was not immediate. Investigators said the advantage became more noticeable after six months, suggesting the immune system needed time to build its response.
Why this vaccine is different
This is not a one size fits all cancer shot. Scientists build it using the genetic information inside each patient’s own tumour. They compare material from the removed melanoma with healthy tissue, usually blood, then use computer analysis to identify mutations that may create neoantigens, abnormal proteins the immune system can potentially recognise as cancer.
Up to 34 of those targets are selected and encoded into messenger RNA. Once delivered into the body, the instructions prompt cells to briefly make harmless pieces of those abnormal proteins, giving immune cells, especially T cells, a chance to learn what to attack if any melanoma cells are still left behind.
Pembrolizumab plays a separate role. It blocks a signal that cancer can use to dampen immune attacks, so the drug helps release the brakes while the vaccine teaches the immune system what to look for. Georgina Long, the trial’s global principal investigator, described the approach as a more personalised way to use the immune system to lower the chance of melanoma returning or leading to death.
How the study was run, and what is still unknown
The trial, known as INTerpath-001, enrolled patients at 157 medical centres around the world. It was randomised and double blinded, meaning neither patients nor treating teams knew who received the vaccine. A total of 757 people got intismeran with pembrolizumab, while 380 received pembrolizumab with a placebo.
Patients were given up to nine injections of the vaccine, spaced three weeks apart, alongside about a year of pembrolizumab. The median follow up was 24.6 months.
Researchers say the result marks the first phase 3 success for an mRNA cancer treatment designed around the specific mutations in an individual patient’s tumour. One key question remains, though. The study has shown the vaccine can help stop melanoma from coming back, but it has not yet shown whether it helps patients live longer overall.
