Keros Therapeutics presents data from Phase 2 RESTORE trial of elritercept

Elritercept Demonstrated Potential to Treat Myelofibrosis and Mitigate Ruxolitinib-Associated Cytopenias in the Phase 2 RESTORE Trial: This ongoing, open-label, two-part Phase 2 clinical trial is evaluating elritercept administered with or without ruxolitinib in patients with MF who have anemia and were either currently on, failed, or ineligible for ruxolitinib at baseline. Safety data are presented for all patients that received at least one dose of elritercept as of the data cut-off date. Evaluations of markers of hematopoiesis and anemia over 12 weeks, along with measurements of spleen volume and symptom scores over 24 weeks, were presented for dose levels 1 through 4 in Part 1 and the RP2D, ranging from 0.75 mg/kg to 5.0 mg/kg. Enrollment of Part 1 of the trial, the dose escalation portion, is complete. Part 2, the dose expansion portion, is open and enrolling with a RP2D of 3.75 mg/kg with the option to up-titrate to 5.0 mg/kg. All data presented from this trial is as of the data cut-off date. Elritercept was generally well-tolerated by the safety population. There were four cases of fatal TEAEs in the trial that were each deemed unrelated to treatment. The most commonly reported TEAEs were thrombocytopenia and diarrhea. The majority of treatment-related TEAEs were mild to moderate, with three patients experiencing Grade 3 or higher treatment-related TEAEs. Additional data from the efficacy evaluable patients include: Increases in hemoglobin were observed in the majority of evaluable non-transfusion dependent patients in both arms over a 12-week period within the first 24 weeks, suggesting that elritercept has the potential to address anemia due to MF and ruxolitinib-associated anemia. 60.6% of patients that received at least three RBC units per 12 weeks at baseline in both arms and all dose levels tested showed reductions in transfusion burden over 12 weeks within the first 24 weeks. 60% of the patients who showed reductions in transfusion burdens had a reduction of 50% or greater in the number of transfusions. Of the patients receiving 3.0 mg/kg of elritercept or higher in combination with ruxolitinib, 72.7% had reduction of 50% or greater and 45.5% of patients achieved TI. At Week 24, some reduction in spleen volume was observed in 52.9% of patients with baseline spleen size greater than or equal to 450 cm3 and a Week 24 spleen assessment, including three patients who had reductions of 35% or greater. Reductions in spleen volume in the combination arm generally occurred without an increase in ruxolitinib dose. At Week 24, some reduction in disease symptoms was observed in a majority of patients with at least two symptoms with an average score greater than or equal to 3 or an average total score of greater than or equal to 10 on the MF-SAF-TSS questionnaire at baseline and a week 24 MF-SAF-TSS assessment. Three patients had reductions of at least 50%, including two in the monotherapy arm and one in the combination arm. The data support the potential of elritercept to ameliorate ineffective hematopoiesis and address cytopenias due to MF and associated with ruxolitinib, and provide broader clinical benefit in patients, as supported by the observed reduction in spleen volume and improvement in total symptom scores.