IMerge Trial: Imetelstat Increases Transfusion Independence Sans Platelet Transfusions, MGF

Results from a subanalysis of the IMerge trial showed that imetelstat led to significant improvement in rates of red blood cell (RBC)-transfusion independence (TI) in patients with lower-risk myelodysplastic syndromes (LR-MDS), absent platelet transfusions or myeloid growth factor (MGF) use. These findings were presented at the Society of Hematologic Oncology 2024 Annual Meeting in Houston, Texas.

IMerge was a phase III, double-blind, placebo-controlled trial in which imetelstat showed significant efficacy for RBC-TI rates in patients with RBC transfusion-dependent (TD) LR-MDS who were relapsed or refractory to or ineligible for erythropoiesis-stimulating agents (ESAs). For this subanalysis, the investigators reported RBC-TI rates in the absence of platelet transfusions and MGF and evaluated RBC-TI in patients with a mean central hemoglobin (Hb) rise of at least 1.5 g/dL.

Patients from 118 global sites received 7.5 mg/kg of intravenous imetelstat (n = 118) or placebo (n = 60) every four weeks until disease progression. The primary endpoint was RBC-TI at eight weeks or longer, and the key secondary endpoint was RBC-TI for 24 weeks or more.

In the imetelstat group, 2% of patients required platelet transfusion and 3% required MGF, compared with 18% and 35%, respectively, in the placebo group. Absent platelet transfusion, rates of RBC-TI were significantly higher in the imetelstat group versus placebo at eight weeks or longer (39% vs 15%), 24 weeks or longer (27% vs 3%), and one year or longer (16% vs 2%). Similarly, rates of RBC-TI were higher absent MGF in the imetelstat group at all time points (eight weeks or longer: 39% vs 15%; 24 weeks or longer: 27% vs 3%; one year or longer: 18% vs 2%).

Patients who received imetelstat had higher rates of RBC-TI with concurrent Hb rise (≥1.5 g/dL) compared with placebo at all time points (eight weeks or longer: 28% vs 2%; 24 weeks or longer: 23% vs 0%; one year or longer: 17% vs 0%). Among patients who achieved RBC-TI, imetelstat increased median central Hb levels higher than placebo (eight weeks or longer: 3.6 g/dL vs 0.8 g/dL; 24 weeks or longer: 4.2 g/dL vs 1.1 g/dL; one year or longer: 5.2 g/dL vs 1.7 g/dL).

“[These] data further support the efficacy of imetelstat in patients with RBC-TD LR-MDS,” the investigators concluded.

Reference

Zeidan AM, Santini V, Platzbecker U, et al. Efficacy of imetelstat on red blood cell-transfusion independence in the absence of platelet transfusions or myeloid growth factors in IMerge. Abstract MDS-156. Presented at the Society of Hematologic Oncology 2024 Annual Meeting; September 4-7, 2024; Houston, Texas.