Summary
Background
Erlotinib is approved for the treatment of all patients with advanced non-small cell lung cancer (NSCLC), but is most active in the treatment of EGFR mutant NSCLC. Cabozantinib, a small molecule tyrosine kinase inhibitor, targets MET, VEGFR, RET, ROS1, and AXL, which are implicated in lung cancer tumorigenesis. We tested the efficacy of cabozantinib and the combination of erlotinib plus cabozantinib, as compared with erlotinib, in patients with EGFR wild-type NSCLC.
Methods
In this three arm, randomised phase 2 study, the primary endpoint was to compare progression-free survival (PFS) of patients treated with cabozantinib versus erlotinib alone, and the combination of erlotinib plus cabozantinib versus erlotinib alone. Patients were eligible if they had received 1–2 previous treatments for advanced non-squamous EGFR wild-type NSCLC. Patients were stratified by performance status and line of therapy, then randomised using permuted blocks within strata to receive open label oral daily dosing of erlotinib (150 mg), cabozantinib (60 mg), or erlotinib (150 mg) and cabozantinib (40 mg). Imaging was performed every 8 weeks. At the time of radiographic progression, there was optional crossover for patients in either single agent arm to receive combination therapy. The comparison between erlotinib and each of the arms was powered (91%) to detect a PFS hazard ratio (HR) of 0.5 (1-sided p-value 0.10-level). Secondary objectives were overall survival (OS), radiographic response by RECIST version 1.1 and description of adverse events by CTCAE version 4.0. This trial is registered with ClinicalTrials.gov, number NCT01708954.
Findings
At complete enrollment, we randomised 125 patients (42 assigned to erlotinib, 40 assigned to cabozantinib, 43 assigned to the combination), of which 111 (89%) were eligible and received treatment per protocol were included in the primary analysis (38, 38, and 35 patients on erlotinib, cabozantinib, and combination, respectively). Compared to erlotinib alone (median 1.8 months), PFS was significantly improved in the cabozantinib arm (4.3 months, HR 0.39, 1-sided p=0.0003, 80% CI 0.27–0.55) and also in the erlotinib plus cabozantinib arm (4.7 months, HR 0.37, 1-sided p=0.0003, 80% CI 0.25–0.53).
The safety analysis population included all patients who received study therapy regardless of eligibility. The most common grade 3 or 4 adverse events were diarrhea (3 [8%] in the erlotinib group vs 3 [8%] in the cabozantinib group vs 11 [28%] in the erlotinib and cabozantinib group), hypertension (none vs 10 [25%] vs 1 [3%]), fatigue (5 [13%] vs 6 [15%] vs 6 [15%]), oral mucositis (none vs 4 [10%] vs 1 [3%]), and thromboembolic event (none vs 3 [8%] vs 2 [5%]). Adverse events that were grade 3 or worse occurred in 13 (33%) patients in the erlotinib group, in 28 (70%) patients in the cabozantinib group, and in 28 (72%) patients in the erlotinib and cabozantinib group. One death of respiratory failure occurred in the cabozantinib group, deemed possibly related to either drug or diseas...
