Moderna-Merck personalized mRNA melanoma vaccine cuts relapse risk in late-stage trial

Moderna and Merck's experimental melanoma vaccine, combined with Keytruda, reduced recurrence or death risk by 42% in a Phase 3 trial. Despite positive results, Moderna's shares fell 18%, likely due to high investor expectations. The vaccine is personalized using mRNA technology, targeting unique tumor mutations. Trial data showed 82.2% of patients treated with the vaccine and Keytruda were alive without recurrence after two years, compared to 70% with Keytruda alone.

Merck (MRK) will acquire Silence Therapeutics (SLN) for $1.3B, or $20 per ADS, an 82% premium. Silence's Phase 3-ready siRNA therapy for polycythemia vera will join Merck's pipeline. The deal, expected to close in Q1 2027, aims to boost Merck's rare disease portfolio and aligns with its specialty healthcare strategy.

Pembrolizumab (Keytruda) plus chemo did not significantly improve event-free survival (EFS) in cisplatin-eligible muscle-invasive bladder cancer (MIBC) patients, per KEYNOTE-866 trial results. Median EFS was 74.1 months with pembrolizumab vs not reached with placebo (HR 0.88, P = .1366). Overall survival (OS) was similar, and pCR rate was higher with pembrolizumab. Adverse effects were consistent with prior reports. The trial enrolled 907 patients, with EFS as the primary endpoint.

Merck and Moderna reported positive results from a cancer vaccine trial. The personalized vaccine, combined with existing immunotherapy, reduced melanoma recurrence by training the immune system to target cancer cells, according to the study.

Moderna (MRNA) shares fell 1% on Friday, following a 17% drop the prior day, as investors reacted to leaked data from a late-stage melanoma vaccine trial. The data, set for official release on Saturday, initially underwhelmed investors. Analysts' price targets vary, with Goldman Sachs at $137, Morgan Stanley at $95, and Citi at $80. The stock has rallied this year on hopes for its cancer treatment pipeline.

Merck's enlicitide (Lipfendra) showed significant LDL-C reduction in patients with reduced kidney function, according to a pooled analysis of phase 3 trials. The FDA approved the drug in July 2026 for lowering LDL-C in adults with hypercholesterolemia, including HeFH. The analysis found placebo-adjusted LDL-C reductions of 65.9% at week 24 in patients with eGFR below 60, with comparable safety to placebo.