Moderna's 177% surge on cancer vaccine lifts biotech sector

Moderna (MRNA) shares rose 177% in a single session Wednesday after the company released late-stage results from a cancer vaccine trial run with Merck (MRK). The stock closed the week up 129%.

The trial tested an mRNA-based vaccine in combination with Merck's Keytruda against a standard of care in patients with high-risk melanoma. The data showed a statistically significant improvement in recurrence-free survival, the companies said. Moderna plans to file for accelerated approval with the FDA this year.

Merck shares hardly moved on the news. The drugmaker trades under Alpha Score 51, indicating a mixed outlook. Moderna scores 46 on the same metric, reflecting the volatility baked into a single-product biotech with a pipeline that, until this readout, had mostly disappointed.

The melanoma market is roughly $3 billion a year in the U.S., dominated by Bristol Myers Squibb's Opdivo and Merck's own Keytruda. A preventive vaccine would slot into the adjuvant setting, where patients get treated after surgery to prevent recurrence. Analysts at Jefferies estimated peak sales of $4 billion if the vaccine wins approval for melanoma and then expands into lung and other solid tumors. They did not provide a timeline for those additional indications.

The rally also lifted other mRNA-focused names. BioNTech, which has its own cancer vaccine collaboration with Genentech, rose 12% in sympathy. CureVac, a smaller German biotech with preclinical mRNA oncology programs, gained 8%. The readout is the first late-stage win for an mRNA cancer vaccine, a category that has drawn significant investment since the Covid-19 vaccine success but produced few clinical results.

The next catalyst for Moderna is the FDA's decision on whether to grant priority review. The company said it expects a filing decision by mid-2026.