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.