Moderna and Merck’s Phase 3 melanoma vaccine trial hit its primary endpoint, cutting the risk of recurrence or death by 42% with intismeran autogene plus pembrolizumab versus pembrolizumab alone, after a median follow-up of about two years. The study also reported a 38% reduction in the risk of cancer spreading or death, reinforcing the strategy of personalized mRNA neoantigen vaccination as an adjuvant approach. The data rollout followed a leak and the companies issued early results ahead of formal presentation at ESMO. While overall survival and quality-of-life endpoints remain to be fully detailed, the magnitude of the recurrence-risk reduction sets a high benchmark for competitors pursuing personalized cancer vaccines. Separate from the melanoma program, the FDA also granted accelerated approval to dostarlimab (Jemperli) in first-line stage II/III microsatellite instability-high (MSI-H) or mismatch repair-deficient (dMMR) locally advanced rectal cancer. The approval is based on the single-arm AZUR-1 trial and uses a clinical complete response endpoint with nonoperative management for responders. Together, the two updates highlight how pembrolizumab-combination regimens and checkpoint-based immunotherapy continue to reshape regulatory pathways for biomarker-defined solid tumors, with growing emphasis on response depth and duration rather than conventional chemo-based comparators.