Moderna stock fell more than 17% to $202.63 on Thursday after detailed results for its melanoma vaccine trial surfaced earlier than scheduled. The decline occurred despite the Phase 3 trial meeting its primary treatment goals when combined with Merck's Keytruda immunotherapy.
Trial results briefly appeared on an oncology website before their planned Saturday presentation. Moderna and Merck subsequently published the findings on Thursday. During intraday trading, Moderna shares fell more than 25%, temporarily erasing approximately $24 billion in market value. The stock recovered some losses by close but weakened again in Friday's premarket session. Merck shares also declined following the announcement.
Trial Outcomes
The INTerpath-001 trial enrolled 1,137 patients with high-risk stage IIB-IV melanoma that had been surgically removed. Participants received either a personalized vaccine called intismeran autogene combined with Keytruda, or placebo with Keytruda. Each vaccine was designed using genetic mutations identified in the patient's individual tumor.
After a median follow-up of 24.6 months, the combination treatment reduced recurrence or death risk by 42% compared with Keytruda alone. Two-year recurrence-free survival reached 82.2% with the combination versus 70% for Keytruda monotherapy. The treatment also reduced the risk of distant cancer spread or death by 38%.
Severe treatment-related side effects occurred in 14.2% of combination patients and 13.4% of comparison patients. The companies reported no new safety concerns.
Analyst Perspective
UBS analyst Michael Yee characterized the recurrence findings as solid overall but attributed the selloff to the stock's substantial prior gains. William Blair analyst Myles Minter raised questions about whether similar benefits would extend to other cancer types. Some analysts noted that the distant-spread reduction trailed expectations from earlier research, though the studies used different methodologies.
Next Steps
Moderna and Merck plan to present the complete trial results on October 24 at a medical conference in Madrid while continuing regulatory discussions. Overall survival data remain incomplete, and the trial has not yet demonstrated a definitive survival benefit.
