Dr Mascarenhas on the IMpact-MF Trial of Imetelstat in R/R Myelofibrosis

"The primary end point [of Impact-MF] is OS. That is unique in the myelofibrosis field because spleen and symptom assessment that are typically the regulatory end points. This [choice of end point] is [therefore seeking to fulfill] an unmet need."

John Mascarenhas, MD, a professor of medicine at the Icahn School of Medicine at Mount Sinai and director of the Adult Leukemia Program at The Tisch Cancer Institute, discussed the primary objective and design of the ongoing phase 3 IMpact-MF trial (NCT04576156) investigating imetelstat (Rytelo) for patients with relapsed or refractory myelofibrosis.

The IMpact-MF study was designed in part to address a significant unmet need in the myelofibrosis treatment paradigm: improving overall survival (OS), Mascarenhas began. It is a randomized phase 3 trial enrolling patients who have progressed on treatment with ruxolitinib or another JAK inhibitor therapy, he detailed. These patients are randomly assigned to receive either imetelstat or best available therapy (BAT). Imetelstat is administered intravenously every 3 weeks, while BAT is determined by investigator’s choice, with the specific exclusion of JAK inhibitors in the control arm.

The primary end point of the IMpact-MF trial is OS, Mascarenhas shared. He noted that this is unique in the myelofibrosis field, as regulatory end points in this setting focus on spleen and symptom assessment. Beyond survival, the study also assesses other crucial end points, including spleen response, symptom response, and anemia response. Of note, anemia responses were observed with imetelstat in the prior phase 2 IMbark trial (NCT02426086).

Mascarenhas pointed out the strong rationale for using this drug in myeloid malignancies, citing that imetelstat is already an approved drug for lower-risk, transfusion-dependent myelodysplastic syndrome, based on data from the phase 3 IMerge trial (NCT02598661). Mascarenhas hopes that the accrual for the ongoing IMpact-MF study will be completed in 2025, after which close follow-up of the patients will be necessary.