Merck and Moderna Present Leaked Melanoma Vaccine Data at ESMO Amid Market Volatility

Key points

• Intismeran autogene combined with Keytruda achieved an 82.2% recurrence-free survival rate at 24 months, compared to 70% for Keytruda alone.
• The combination reduced the risk of distant metastasis or death by 38%, with a distant metastasis-free survival rate of 88.5% versus 80.2% in the control group.
• A premature leak of the data on Thursday triggered a 25% drop in Moderna shares, even though the results exceeded Wall Street expectations.
• Merck’s Shweta Jain stated that the presentation content remained unchanged despite the leak, emphasizing the clinical significance of the results.
• Merck is preparing to submit the data to the FDA for approval next year and has initiated phase 2 trials for the vaccine in renal cell carcinoma, bladder cancer, and non-small cell lung cancer.

Background

Merck and Moderna began collaborating on mRNA vaccines in 2016. Intismeran autogene is a personalized vaccine designed to target neoantigens in cancer patients. Previous phase 2 trials had generated high expectations for efficacy, which contributed to significant investor interest. Moderna’s stock had risen more than 530% year-to-date before the leak, while Merck’s stock had climbed nearly 41%. The companies are also exploring other oncology therapies, including the antibody-drug conjugate sac-TMT, to diversify their pipeline beyond Keytruda.

How outlets are covering it

Fierce Biotech highlighted Merck’s confidence in the data, with Shweta Jain describing the results as a validation of the long-standing collaboration and emphasizing the potential for curative outcomes. CNBC focused on the market reaction, noting that Moderna’s stock fell 25% despite the positive data, driven by the premature leak and high prior expectations. STAT covered the event as a major highlight of the ESMO Congress, noting the presence of nearly 40,000 attendees and the broader context of other cancer therapies being presented. All sources agreed that the clinical results were significant, but differed in emphasis: Fierce focused on the scientific and collaborative aspects, CNBC on the financial impact, and STAT on the conference context.

Why it matters

The phase 3 results for intismeran autogene represent a potential breakthrough in personalized cancer treatment, offering a 42% reduction in recurrence or death for melanoma patients. The data supports the viability of mRNA-based vaccines in oncology and could lead to FDA approval next year. The incident also highlights the challenges of managing high-profile clinical data releases in a volatile market, where even positive results can trigger sell-offs if expectations are too high. The expansion of the vaccine to other cancer types could further diversify Merck and Moderna’s pipelines and reduce reliance on Keytruda.

What to watch

Merck is preparing to submit the phase 3 data to the FDA for approval, aiming for a decision next year. The company has also initiated phase 2 trials for intismeran autogene in renal cell carcinoma, bladder cancer, and non-small cell lung cancer. Merck and Moderna will continue to present other oncology data at ESMO, including results for the antibody-drug conjugate sac-TMT. Investors will monitor the stock performance of both companies in the coming weeks as the market digests the full implications of the data.