Clinical Efficacy and Patient-Reported Outcomes from Phase 3 IMerge Trial
Panelists discuss how the IMerge trial data demonstrate imetelstat’s efficacy in SF3B1-negative patients with lower-risk MDS who failed ESA therapy, achieving substantial hemoglobin improvements (averaging 4-5 g/dL in responders) with meaningful transfusion independence rates. They debate the clinical significance of modest patient-reported quality-of-life improvements and question whether historical hemoglobin ceiling limits should be reconsidered given robust treatment responses.
EP: 1.Long-Term Update on Efficacy and Safety in Phase 3 COMMANDS Trial
EP: 2.Expert Perspectives on Long-Term COMMANDS Findings
EP: 3.Real-World Outcomes From 1L ESA vs Luspatercept Use in LR-MDS
EP: 4.Long-Term Updates From Phase 3 MEDALIST Trial
EP: 5.Clinical Efficacy and Patient-Reported Outcomes from Phase 3 IMerge Trial
EP: 6.Debate Round 1: Treatment Choices for RS-, EPO < 200 mU/mL LR-MDS (1L Luspatercept or ESA)
Clinical Efficacy and Patient-Reported Outcomes From Phase 3 IMerge Trial
The phase 3 IMerge trial evaluated imetelstat, a first-in-class telomerase inhibitor, in patients with lower-risk or intermediate-1 MDS who relapsed after or whose disease was refractory to ESAs or had baseline serum erythropoietin levelsless than500 mU/mL, making them ineligible for ESA therapy. Eligible patients were transfusion dependent, defined as requiring 4 units or more of red blood cells within 8 weeks, and had not previously received hypomethylating agents or lenalidomide. Approximately 178 patients were randomly assigned 2:1 to imetelstat or placebo. The updated outcomes focused particularly on the SF3B1-negative subgroup with a median follow-up of 26 months, where baseline transfusion burden was high and median time from diagnosis to enrollment was nearly 3 years.
In this subgroup, imetelstat achieved meaningful clinical benefit: 33% of patients attained transfusion independence for 8 weeks or more, 21% for 24 weeks or more, and 13% for 1 year or more. Responders showed prolonged durability, with median durations of 44, 123, and 141 weeks, respectively. Hemoglobin improvements were notable, with median rises of 4 to 5 g/dL among responders, restoring many patients to near-normal levels. These findings highlight imetelstat’s potential as a transformative therapy in patients who had few prior options, particularly given the lack of effective treatments for SF3B1-negative disease. Importantly, this study challenges historical safety concerns regarding higher hemoglobin thresholds, as patients who achieved normalization did not demonstrate adverse outcomes, suggesting prior restrictions may be outdated.
The trial also incorporated patient-reported outcomes, a critical consideration in chronic hematologic malignancies. Measures included total fatigue burden, physical functioning, and emotional well-being. Responders demonstrated significant improvements in physical burden scores compared with nonresponders, though only about half of patients reported meaningful quality-of-life improvement despite robust hematologic responses. Experts note that this discrepancy may reflect limitations of assessment tools rather than lack of true benefit, as disease-related clinic visits and ongoing transfusion monitoring still affect patients’ lived experience. The panelists conclude that imetelstat represents an important new option for patients with lower-risk MDS, especially those with SF3B1-negative disease, while underscoring the need for refined end points that better capture functional and quality-of-life outcomes alongside traditional transfusion independence.
