INCB84344-201: Ponatinib and steroids in frontline therapy of unfit patients with Ph+ acute lymphoblastic leukemia

Abstract

Tyrosine kinase inhibitors have improved survival for patients with Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL). However, prognosis for old or unfit patients remains poor. In the INCB84344-201 (formerly GIMEMA LAL 1811) prospective, multicenter, phase 2 trial, we tested the efficacy and safety of ponatinib plus prednisone in newly diagnosed patients with Ph+ ALL aged ≥60 years, or unfit for intensive chemotherapy and stem cell transplantation. Forty-four patients received oral ponatinib 45 mg/day for 48 weeks (core phase), with prednisone tapered to 60 mg/m2/day from days -14 to 29. Prophylactic intrathecal chemotherapy was administered monthly. Median age was 66.5 years (range, 26-85). The primary endpoint (complete hematologic response [CHR] at 24 weeks) was reached in 38/44 patients (86.4%); complete molecular response (CMR) was reached in 18/44 patients (40.9%) at 24 weeks. 61.4% of patients completed the core phase. As of April 24, 2020, median event-free survival was 14.31 months (95% CI 9.30, 22.31). Median overall survival and duration of CHR were not reached; median duration of CMR was 11.6 months. Most common treatment-emergent adverse events (TEAEs) were rash (36.4%), asthenia (22.7%), alanine transaminase increased (15.9%), erythema (15.9%), and gamma-glutamyltransferase increased (15.9%). Cardiac and vascular TEAEs occurred in 29.5% (grade ≥3, 18.2%) and 27.3% (grade ≥3, 15.9%) of patients, respectively. Dose reductions/interruptions/discontinuations due to TEAEs occurred in 43.2%/43.2%/27.3% of patients; 5 patients had fatal TEAEs. Ponatinib and prednisone had efficacy in unfit patients with Ph+ ALL; however, a lower ponatinib dose may be more appropriate in this population. (This trial is registered at www.clinicaltrials.gov as NCT01641107).