Geron Halts Phase 3 IMpactMF Myelofibrosis Trial on Futility Finding, Shares Sink More Than 20%

Geron Corporation has discontinued its Phase 3 IMpactMF clinical trial evaluating imetelstat in patients with JAK inhibitor-relapsed or refractory myelofibrosis after an independent Data Monitoring Committee determined the study was unlikely to meet its primary endpoint of overall survival. The trial had enrolled 327 subjects and was comparing imetelstat against best available therapy. The committee found no new safety concerns, meaning the halt was driven entirely by a futility assessment on efficacy.

With the myelofibrosis program now ceased, Geron is shifting its commercial focus entirely to RYTELO, its branded form of imetelstat that already holds regulatory approvals in both the United States and the European Union for lower-risk myelodysplastic syndromes. The decision eliminates one of the company's two major development bets and concentrates the business on a single approved indication.

Geron shares fell sharply on the news, dropping more than 20% and trading around $0.90, reflecting investor concern over the loss of the myelofibrosis growth opportunity. The company filed an 8-K with the SEC on October 28, 2026 formalizing the discontinuation.