What the trial found
INTerpath-001 enrolled 1,137 people whose melanoma, stage IIB to IV, had been fully removed. Some received the personalized mRNA vaccine intismeran together with pembrolizumab (Keytruda), the rest got placebo plus pembrolizumab. After a median of 24.6 months, the risk of recurrence or death was 42% lower (hazard ratio 0.58). At two years, 82.2% of patients on the vaccine were free of recurrence, against 70.0% in the comparison group.
What sits behind the number
The 42% is a relative reduction. In absolute terms the gap at two years is about 12 percentage points. During the first six months the two groups looked almost the same, and the advantage showed up later. Overall survival data are still immature, and the companies only mention a favorable trend. There was no vaccine-only arm, so the vaccine's own contribution cannot be separated out.
Safety and status
Severe side effects of grade 3 to 5 appeared in 14.2% of vaccine patients and 13.4% of the control group. The most common complaints were fever, pain at the injection site and fatigue. The drug is still investigational and the companies say they are talking to regulators. Each dose is made for one patient's tumor, and production takes roughly six weeks.