Phase 1 Study of Cabozantinib in Japanese Patients With Expansion Cohorts in Non–Small-Cell Lung Cancer

Abstract

BackgroundCabozantinib inhibits tyrosine kinases including MET, AXL, VEGFR2, RET, KIT, and ROS1 and has demonstrated antitumor activity in multiple tumor types. The primary objective of this phase 1 study (NCT01553656) was to determine the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) of cabozantinib in Japanese patients. Patients and MethodsPatients with advanced solid tumors were enrolled at 2 sites in Japan. After determining the MTD and RP2D, an expansion in non–small-cell lung cancer (NSCLC) consisting of 3 molecularly defined cohorts (EGFR mutation; KRAS mutation; ALK, RET, or ROS1 fusion) was initiated. The study was registered with ClinicalTrials.gov (NCT01553656). ResultsForty-three Japanese patients were enrolled (dose escalation, n = 23; NSCLC expansion, n = 20). The MTD of cabozantinib capsules was 60 mg daily, and the RP2D of cabozantinib tablets was 60 mg daily. Dose-limiting toxicities were hypertension, proteinuria, and venous embolism. Safety and pharmacokinetics in Japanese patients were consistent with those in non-Japanese patients. Common adverse events included palmar–plantar erythrodysesthesia, hypertension, and diarrhea. Reduction in tumor lesion size was observed in multiple tumor types in the dose-escalation cohorts, with partial responses observed in 4 of 9 patients with NSCLC (EGFR mutation, n = 1; ALK fusion, n = 2; and RET fusion, n = 1). In the NSCLC expansion, 4 patients with EGFR-mutant NSCLC had partial responses; the remaining 16 (EGFR mutation, n = 11; KRAS mutation, n = 2; ALK fusion, n = 1; and RET fusion, n = 2) had stable disease as best response. ConclusionCabozantinib had a manageable safety profile in Japanese patients with solid tumors. Responses were observed in diverse molecular subtypes of NSCLC.