Moderna's melanoma vaccine succeeds in major trial. So why did its stock plunge?

Moderna and Merck reported late-stage trial results showing their personalized mRNA melanoma vaccine, intismeran, reduced relapse risk by 42% when combined with Keytruda. The trial involved 1,137 patients, with 82% of vaccine recipients showing no recurrence after two years, compared to 70% for the placebo group. The companies plan to present the findings at a medical conference and continue long-term studies.

Moderna's cancer vaccine trial showed a 42% reduction in melanoma recurrence risk when combined with immunotherapy, but investors reacted negatively, causing shares to drop 19%. Analysts noted the results fell short of expectations. Merck, the co-developer, faces challenges as Keytruda's patent nears expiration. Experts highlight cost and patient-specific factors in treatment decisions.

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.