Moderna and Merck mRNA Cancer Vaccine Cuts Melanoma Recurrence Risk 42% in First Phase 3 Win as Oncology Data Flood ESMO 2026

Moderna and Merck reported that their personalized mRNA cancer vaccine, intismeran autogene (mRNA-4157), combined with Merck's Keytruda, reduced the risk of melanoma death or recurrence by 42% in the first-ever Phase 3 trial of the therapy, a landmark result that validates the mRNA cancer vaccine platform. Despite the headline success, the focus for investors and clinicians now shifts to whether the vaccine can prevent relapse at longer follow-up horizons, with nine total Phase 2 and Phase 3 studies ongoing across melanoma, non-small cell lung cancer, bladder cancer, and renal cell carcinoma. Moderna shares fell roughly 1% on the data release, a sign that some of the result had been priced in after the companies had telegraphed trial success in August without releasing full numbers.

The ESMO 2026 congress also brought a wave of oncology trial readouts across the industry. Xencor presented dose-selection data from its Phase 1 study of XmAb819, a first-in-class ENPP3 x CD3 bispecific T-cell engager in advanced clear cell renal cell carcinoma, with results delivered by City of Hope's Sumanta Pal. The data cover expansion cohorts used to identify a recommended Phase 3 dose, with a pivotal monotherapy study in ccRCC planned to begin in 2027. Genmab reported updated Phase 2 results for petosemtamab in colorectal cancer, data the company had flagged at its second-quarter earnings call as a catalyst for initiating two Phase 3 studies, one in first-line and one in second-line settings.

Pfizer, meanwhile, published a path forward for a cancer drug that had already failed a late-stage survival trial, the antibody-drug conjugate sigvotatug vedotin, which had not significantly improved overall survival versus docetaxel in advanced lung cancer. The company is assessing which patient subgroups or settings might still support a viable development program for the Seagen-acquired asset. NovaBridge also reported Phase 1b data for a gastric cancer drug at the same congress.