Geron halts phase 3 Rytelo trial after data monitoring panel deems unlikely to improve survival in JAK-inhibitor-pretreated myelofibrosis

Geron announced the discontinuation of its phase 3 IMpactMF trial of Rytelo (imetelstat) in patients with myelofibrosis who had previously failed JAK inhibitor therapy.

The decision followed an interim analysis by an independent data monitoring committee, which concluded the drug was unlikely to achieve a statistically significant overall survival benefit, the trial’s primary endpoint.

The trial enrolled 327 intermediate‑2 or high‑risk myelofibrosis patients and compared Rytelo to best available therapy. The news sent Geron’s shares down about 16% to under $1, the lowest level since March 2020.

Geron’s R&D chief said the company will review the data to learn from the outcome, while Novartis is preparing a delayed FDA filing for its own blood‑cancer candidate pelabresib.