Efficacy and safety of luspatercept in non-transfusion-dependent β-thalassemia: long-term results from the BEYOND study.

Chronic anemia due to non-transfusion-dependent β-thalassemia (NTDT) can result in clinical morbidities, particularly with inadequate management. Luspatercept was previously shown to improve hemoglobin levels in patients with NTDT in the phase 2, randomized, double-blind, placebo-controlled BEYOND trial (ClinicalTrials.gov identifier: NCT03342404). Here, we report long-term efficacy and safety results from the final analysis of BEYOND spanning an additional 26 months (∼2.2 years) of follow-up. Median treatment duration was 202.8 weeks for luspatercept and 61.1 weeks for placebo. Overall, 94.8% and 22.4% of patients in the luspatercept and placebo arms, respectively, achieved a mean hemoglobin increase from baseline ≥1.0 g/dL during any 12-week interval, with mean durations of response of 1136.0 and 203.3 days, respectively. Patient-reported tiredness and weakness showed sustained improvement with luspatercept treatment. The most common treatment-emergent adverse events in the luspatercept group were headache (45.8% vs 20.4% with placebo), bone pain (43.8% vs 6.1%), back pain (39.6% vs 12.2%), and arthralgia (38.5% vs 16.3%). Treatment-emergent extramedullary hematopoiesis events were reported in 12 (9.0%) and 2 (4.1%) patients receiving luspatercept and placebo, respectively, although differences in treatment exposures prevented informative comparisons. Of the 4 patients receiving luspatercept who reported thromboembolic events, all had >1 risk factor. These results show that luspatercept led to a sustained increase in hemoglobin levels in patients with NTDT for up to ∼4.6 years of treatment, with a consistent safety profile and no new safety findings. Luspatercept is a valuable treatment option for patients with NTDT, addressing the need for effective long-term treatment of anemia. This trial was registered at www.clinicaltrials.gov as #NCT03342404.