Clinical Trials

Geron is a late-stage clinical biopharmaceutical company focused on the development and potential commercialization of our first-in-class telomerase inhibitor, imetelstat, in hematologic myeloid malignancies.

Phase 2 clinical data strongly suggest imetelstat may have disease-modifying activity through the apoptosis of malignant stem and progenitor cells, which allows potential recovery of normal hematopoiesis. Geron's imetelstat development program includes two ongoing registration-enabling studies, IMerge™, a Phase 2/3 clinical trial in lower risk myelodysplastic syndromes (MDS), and IMpactMF, a Phase 3 clinical trial in refractory myelofibrosis (MF). 


The Phase 3 portion of the IMerge™ clinical trial is open for screening and enrollment to test the hypothesis that imetelstat improves the rate of red blood cell transfusion independence (RBC-TI) compared to placebo. To be eligible for the trial, patients need to have non-del(5q) lower risk MDS, be transfusion dependent and have relapsed after or are resistant to treatment with erythroid stimulating agents (ESAs). Patients must also be naïve to treatment with hypomethylating agents (HMAs) and lenalidomide. The Phase 2 portion of IMerge™ is no longer enrolling patients.


The IMpactMF Phase 3 clinical trial in refractory MF is open for screening and enrollment. The study is designed to evaluate a potential improvement in overall survival of participants treated with imetelstat compared to best available therapy. To be eligible for the trial, patients need to have Intermediate-2 or High-risk MF and also non-responsive, or refractory, to treatment with a janus kinase (JAK) inhibitor. 


To learn more about clinical trials, please visit To see clinical trials that are currently underway and to find out if a study is enrolling patients with your condition and in your area, including IMerge, please visit If you have any questions regarding ongoing clinical trials of imetelstat, please contact

Recent Phase 2 clinical data are available at