A phase 2 clinical trial of luspatercept in non-transfusion-dependent patients with myelodysplastic syndromes.

Luspatercept has shown durable clinical efficacy for the treatment of anemia in transfusion-dependent patients with lower-risk myelodysplastic syndromes (LR-MDS). We report the results of a prespecified primary analysis of a phase 2 trial of luspatercept in non-transfusion-dependent (NTD) Japanese patients with anemia due to LR-MDS. Luspatercept (starting dose 1.0 mg/kg) was administered subcutaneously once every 3 weeks. The primary endpoint was the proportion of patients who achieved hematological improvement-erythroid (HI-E) response (≥ 1.5 g/dL increase in hemoglobin level for 8 weeks) without transfusions within the first 24 weeks of treatment. At the primary analysis data cutoff, 21 patients had been enrolled/treated; 17 and 10 patients had completed 24 and 48 weeks of treatment, respectively. HI-E response occurred within 24 weeks in 10 patients (47.6%; 95% confidence interval, 25.7-70.2; P < 0.0001), which was significantly higher than the predefined threshold (10%). By week 48, HI-E response occurred in 12 patients (57.1%) and 17 patients (81.0%) remained NTD. Luspatercept was well tolerated. Three patients (14.3%) had grade 3-4 treatment-related treatment-emergent adverse events. Luspatercept resulted in statistically and clinically significant improvements in hemoglobin levels, and may help delay the need for transfusions in NTD patients with LR-MDS.