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

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.