Population Pharmacokinetic and Exposure-Response Analyses for Ponatinib in the Phase 3 PhALLCON Study

In March 2024, ponatinib received accelerated FDA approval for the treatment of newly diagnosed Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph + ALL) in combination with chemotherapy based on the Phase 3 PhALLCON study (NCT03589326), which demonstrated a higher rate of minimal residual disease (MRD)-negative complete remission (CR) at the end of induction (EOI) with ponatinib (34.4%) versus imatinib (16.7%; p = 0.002). Patients received ponatinib (30 mg QD with reduction to 15 mg QD upon achievement of MRD-negative CR at EOI) or imatinib (600 mg QD) combined with 20 cycles of reduced-intensity chemotherapy (induction: 3 cycles; consolidation: 6 cycles; and maintenance: 11 cycles). Ponatinib pharmacokinetics (PK) were similar in patients in PhALLCON and patients in a previous population PK analysis. Bayesian re-estimation of the previously developed population PK model adequately described PhALLCON PK data. Exposure-efficacy analyses did not identify a significant relationship between ponatinib exposure and the probability of MRD-negative CR at EOI (p = 0.619), suggesting a consistent efficacy benefit across exposures. Ponatinib exposure was not a significant predictor of arterial occlusive events, venous thromboembolic events, thrombocytopenia, or lipase increase (p > 0.05). However, higher exposures were associated with a higher probability of hypertension (p = 0.0340) and alanine aminotransferase (ALT) increase (p = 0.0034). Dose reduction from 30 to 15 mg was predicted to decrease the odds of experiencing hypertension by 37.7% and ALT increase by 44.2%. Collectively, exposure-response analyses support a favorable benefit-risk profile of the approved ponatinib dosage (30 mg QD reduced to 15 mg QD upon achievement of MRD-negative CR at EOI), combined with chemotherapy, for frontline treatment of Ph + ALL.