12/19/24
Emily Estrada
According to research presented by Justin Watts, MD, Sylvester Cancer Center Institute, University of Miami, Miami, Florida at the 2024 American Society of Hematology (ASH) Annual Meeting & Exposition in San Diego, California, INCB057643 may improve patient outcomes in the treatment of hematologic malignancies, including myelofibrosis (MF).
A small-molecular bromodomain and extra-terminal BET protein inhibitor, INCB057643, has shown safety and tolerability as monotherapy and combination with Janus kinase (JAK) 1 and 2 inhibitors among patients with MF in previous phases of the ongoing phase 1/2 clinical trial. In this dose-escalation and expansion portion of the trial, the dose of INCB057643 in patients with MF receiving monotherapy was increased from 4mg to 12mg and for patients with MF who had an inadequate response to ruxolitinib, combination therapy dosage was increased from 4mg to total maximum dosage.
The primary end points were safety and tolerability, as well as dose-limiting toxicities of INCB057643 at 24 weeks. The secondary end points included spleen volume reduction greater than 35% from baseline (SVR35), symptom reduction by greater than 50% from baseline via MPN-Symptom Assessment Form (TSS50), and anemia response of a hemoglobin increase at least 1.5 g/dL from baseline in patients that were not receiving transfusions or transfusion-free for at least 12 weeks for patients dependent on transfusions at baseline.
Patients with relapsed/refractory MF (84.1%%), essential thrombocythemia ([ET]; 4.5%), myelodysplastic syndromes (MDS), or myeloproliferative neoplasm (MPN) syndromes (11.4%). were included in the study. In total, 18 patients were treated with a monotherapy dose escalation and 10 patients received dose expansion. Combination therapy dose escalation was received by 16 patients whose median age was 71 years and whose median ruxolitinib dose was 22.4mg per day. The median duration of INCB057643 exposure was 195.5 days for patients in the monotherapy dose-escalation cohort and 139.0 days for patients in the dose-expansion cohort. As for patients who were in the combination therapy dose-escalation cohort, median INCB057643 exposure was 194.0 days.
At 24 weeks, 3 out of 16 patients who received monotherapy achieved SVR35 and 5 out of 14 achieved TSS50 with any dose of INCB057643, of which 3 received a dose of at least 10 mg. During any time of treatment, improvements in spleen volume and TSS50 best response were demonstrated by 13/19 and 12/15 patients, respectively. Among patients who received combination therapy of INCB057643 and ruxolitinib, 3 out of 12 patients achieved SVR35 and 6 out of 11 achieved TSS50 at any combo dose. Improvements were seen at any time during treatment for both SVR35 and TSS50 in 13 out of 16 and 10 out of 15 patients, respectively. Of patients not dependent on blood transfusions, an anemia response was demonstrated by 3 patients in both the monotherapy and the combination group. Additionally, of 6 patients who were blood transfusion dependent at BL, 2 achieved transfusion independence.