Merck and Moderna disclose phase 3 cancer vaccine data early after leak, showing improved recurrence-free survival with Keytruda

Merck & Co. and Moderna were forced to release their phase 3 trial results for the intismeran autogene cancer vaccine two days ahead of schedule after an unexpected leak of the data ahead of the ESMO Presidential Symposium.

The data showed that at 24 months, patients receiving the vaccine together with Keytruda achieved a recurrence‑free survival rate of 82.2%, compared with 70% for Keytruda alone, corresponding to a hazard ratio of 0.58 and a 42% reduction in risk of recurrence or death in melanoma.

However, the distant metastasis‑free survival outcome did not meet the expectations set by the earlier phase 2 readout, with the vaccine cohort reporting an 88.5% rate versus 80.2% in the control group.

The premature disclosure rattled investors, and the share prices of both companies fell as the market digested the mixed results.