Treatment with elritercept was effective for patients with lower-risk myelodysplastic syndromes, according to phase 2 data that will be presented during the poster sessions at the Fourteenth Annual Meeting of the Society of Hematologic Oncology in Houston, Texas.
Elritercept, an investigational modified activin receptor type IIA ligand trap, was well-tolerated and associated with rapid, durable transfusion and erythroid responses, including in patients with ring sideroblast (RS)–negative MDS or high transfusion burden, wrote the authors, led by Rami Komrokji, MD, of the Moffitt Cancer Center in Tampa, Florida.
The phase 2 study enrolled transfusion-dependent and non-dependent patients with very low, low, or intermediate risk MDS and chronic myelomonocytic leukemia. Elritercept was evaluated at 3.75 mg/kg every 4 weeks, with optional up-titration to 5 mg/kg. Endpoints included red blood cell transfusion independence and hematologic improvement in erythroids. HI-E was defined as a mean hemoglobin increase of 1.5 g/dL or more for low transfusion burden patients, or a transfusion burden reduction of four or more red blood cell units per eight weeks versus the eight-week pretreatment period for HTB patients.
The analysis covered 96 patients with LR-MDS with a median treatment exposure of 13.8 months. Any-grade treatment-emergent adverse events related to elritercept occurred in 45.8% of patients, most commonly nausea (7.3%) and diarrhea (6.3%). Grade 3 or higher TEAEs occurred in 5.2% of patients.
By week 24, 38.5% of evaluable patients achieved TI for eight or more weeks. Among subgroups, TI rates were 29.3% for HTB, 44.2% for RS–positive, 28% for RS–negative, 37.2% for HTB with erythropoietin (EPO) below 500 units/L, 48.9% for RS–positive with EPO below 500 units/L, and 43.8% for RS–negative with EPO below 500 units/L.
By week 48, 26.9% of patients achieved transfusion independence for 24 or more weeks, including 15.5% HTB patients. Median time to first transfusion independence outcome was 0.4 weeks (95% CI, 0.3-5.3), and 67.3% of patients with TI for eight or more weeks sustained TI to 24 or more weeks. Median duration of TI was 110.9 weeks (95% CI, 24.3-not estimable) in patients with TI for eight or more weeks by week 24.
By week 24, 49% of evaluable patients achieved HI-E. Among subgroups, HI-E rates were 48.3% for HTB, 51.9% for EPO below 500 units/L, 53.1% for RS–positive, and 38.7% for RS–negative. The median time to HI-E was 3.1 weeks (95% CI, 1.1-8.1), and median duration of HI-E was 43.9 weeks (95% CI, 24.6-59.1).
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