In brief
- Moderna (MRNA) jumped ~131% Wednesday after the Phase 3 INTerpath-001 trial of intismeran autogene plus Keytruda hit its RFS and DMFS endpoints in resected melanoma.
- Intismeran autogene is a personalized mRNA neoantigen therapy built from each patient's tumor mutations, paired with Merck's Keytruda immunotherapy.
- Traders shorting Moderna faced ~$4.8B in mark-to-market losses as the stock doubled; short interest sat at 13.5% of free float.
Moderna's personalized mRNA cancer shot cleared its first Phase 3 readout, and the market reacted like it had won more than a trial.
Shares of Moderna, which trades as MRNA, surged about 131% on Wednesday, more than doubling to near $148 after touching $163 intraday, a record one-day jump. Merck (MRK), the larger partner that sells Keytruda, also spiked on the news.
The companies said the Phase 3 INTerpath-001 trial of intismeran autogene plus Keytruda met its recurrence-free and distant-metastasis-free survival goals in patients whose stage IIB–IV melanoma had been surgically removed.
It's the first positive Phase 3 result for a personalized neoantigen therapy, and the first for an mRNA-based cancer treatment.
What the therapy actually does
Intismeran autogene (also called V940 or mRNA-4157) isn't a mass-produced vial. Doctors sequence a patient's tumor, map its unique mutations, and the mRNA teaches the body to manufacture neoantigens—protein fragments the immune system learns to spot and attack.
Keytruda, an anti-PD-1 drug, lifts the brakes on immune cells. Together they're meant to scrub out any cancer surgery left behind.
The combo developed by Moderna and Merck beat Keytruda alone, the current standard of care, on both endpoints. That's the first time a personalized neoantigen therapy has shown a clinically meaningful edge over the blockbuster immunotherapy in the adjuvant setting (treatment after surgery to prevent return). For Moderna, which has leaned on a collapsed COVID franchise and carried one of the heaviest short bets among large caps, the readout lands at a make-or-break hour.
It also lit a fuse. When a heavily shorted stock rockets, borrowers scramble to buy back and stop the bleeding—the same short-squeeze mechanics that rattled markets during the 2021 GameStop frenzy. Crypto-linked equities recently handed short sellers $2.6 billion in losses as rallies reversed, and Moderna's move was far bigger..
"With each shorted share now down almost $100, that is exactly the kind of pressure that can trigger a squeeze," ORTEX co-founder Peter Hillerberg said in a statement.
The trial will continue to evaluate overall survival and other secondary endpoints not yet reported.