The INTerpath-001 trial tested intismeran autogene, also known as V940 or mRNA-4157. The vaccine is made for each patient after genetic sequencing of their tumor. Everyone enrolled had melanoma from stage IIB to stage IV that had been completely removed by surgery. Reports differ on what the comparison group received. One account says the combination was compared with pembrolizumab, sold as Keytruda, given alone. Another says patients in the control group got pembrolizumab plus a placebo vaccine. The two accounts also give different enrollment figures: 1,137 patients in one and 1,130 in the other.

The more detailed of the two reports gives a median follow-up of 24.6 months. By its figures, 82.2% of patients on the combination were alive without relapse at two years, against 70% in the control group. Two-year survival without distant metastasis was 88.5% compared with 80.2%, and the risk of distant metastasis or death fell by 38%. Overall survival data are not yet mature, though that report says a favorable trend was seen.

The same report says 95.8% of patients on the combination had treatment-related side effects, including fever, injection site pain and fatigue. Severe adverse events, grade 3 or higher, occurred at similar rates in both arms, at 14.2% in the combination group and 13.4% in the control group.

Georgina Long of Melanoma Institute Australia and the University of Sydney, the trial's principal investigator, called the results a "defining moment," according to that report.

The other account says the phase 3 findings replicate an earlier phase 2 study, which showed a 49% reduction in risk. In that account, Dr. David Berman, Moderna's chief development officer, said the treatment effect appears to begin six months into therapy. The same report describes the mRNA approach as scalable, with each vaccine developed within weeks. It says the companies are studying the combination in nine other trials covering cancers that include pancreatic, gastric and non-small cell lung cancer.