CML-089: Retrospective Independent Review of Arterial Occlusive Events (AOEs) in the Ponatinib Phase 2 PACE Trial (NCT01207440) in Patients with Philadelphia Chromosome Positive (Ph+) Leukemia

Abstract

Objectives In the PACE trial 5-year analysis evaluating use of ponatinib in patients with refractory chronic myeloid leukemia (CML) and Ph+ acute lymphoblastic leukemia, a 25% incidence of AOEs was identified (Cortes, Blood 2018) using Medical Dictionary for Regulatory Activities (MedDRA) preferred terms (PTs). We performed a retrospective review using a charter-based independent Adjudication Committee (AC) to better understand clinically relevant AOE rates in PACE. Methods The AC (3 cardiologists, 1 hematologist, and 1 neurologist) evaluated AOEs (identified using >500 terms) in PACE using established definitions developed by the American College of Cardiology/American Heart Association (ACC/AHA), US Food and Drug Administration (FDA), and Standardized Data Collection for Cardiovascular Trials Initiative (SCTI). The AC also reviewed patient profiles including event, severity, concomitant medication, and hospitalization data. These adjudicated results were compared with pre-adjudication MedDRA PT search results. The AC was blind to dose, dose modification, and investigator causality opinion. Events not associated with a cardiovascular etiology or that failed to meet the ACC/AHA, FDA, and SCTI definitions were determined by the AC not to be AOEs. Results This review included all 449 heavily pretreated patients with Ph+ leukemia enrolled in PACE (median age, 59 y; 47% female; 93% ≥2 tyrosine kinase inhibitors). At a median follow-up of 37.3 months, adjudicated AOEs occurred in 17.4% of the overall patient population compared with 24.7% pre-adjudication. The majority of the pre-adjudication serious AOEs were adjudicated as serious AOEs (20% pre-adjudication vs 16% adjudicated). The most common adjudicated AOE (>2%) was peripheral arterial occlusive disease. Exposure-adjusted incidence of newly occurring adjudicated AOEs decreased over time. Analyses by baseline risk factors demonstrated that patients with the following baseline risk factors had higher incidence rates of adjudicated AOEs than those without ischemic cardiac disease, hypertension, hypercholesterolemia, and diabetes. Conclusions Independent AC review of the PACE trial identified a lower rate of clinically relevant AOEs than previously reported, suggesting an earlier possible overestimation that may not accurately reflect the risk of AOEs with ponatinib. The ongoing ponatinib dose-ranging OPTIC study will further evaluate dose-dependent AOE incidence rates.