A Phase II Study of the Multikinase Inhibitor Ponatinib in Patients With Advanced, RET-Rearranged NSCLC

Introduction RET rearrangements define a distinct molecular subset of NSCLC. The multikinase inhibitor ponatinib reveals potent activity in preclinical models of RET-rearranged NSCLC. Methods In this single-arm, multicenter, phase II trial, we evaluated the clinical activity of ponatinib in patients with advanced, previously treated, RET-rearranged NSCLC (NCT01813734). RET rearrangements were identified through fluorescence in situ hybridization or next-generation sequencing. Ponatinib was administered at a dose of 30 mg once daily. Patients without a documented objective response were eligible to dose-escalate ponatinib to 45 mg daily. The primary end point was objective response rate. Results Between August 2014 and December 2017, nine patients were enrolled. The median age was 58 years (range 49–73 y). Eight patients (89%) had a history of brain metastases. The median number of previous lines of therapy was three (range 1–5). Of the nine evaluated patients, five (55%) experienced tumor shrinkage from baseline, but no confirmed responses were observed (objective response rate 0%). The disease control rate was 55%. With a median follow-up of 9.33 months, the median progression-free survival and overall survival were 3.80 months (95% CI: 1.83–5.30) and 17.47 months (95% CI: 6.57–19.20), respectively. The most common treatment-related adverse events were rash (n = 5; 56%), constipation (n = 4; 44%), and diarrhea (n = 4; 44%). No treatment-related thromboembolic or cardiac events were observed. The study was stopped prematurely owing to slow accrual and lack of clinical activity. Conclusions Ponatinib has limited clinical activity in patients with RET-rearranged NSCLC. Continued development of more potent and selective RET inhibitors is needed.