A phase Ib, dose-finding study of erlotinib in combination with a fixed dose of pertuzumab in patients with advanced non-small-cell lung cancer

Abstract Background Pertuzumab, a dimerization inhibitor of human epidermal growth factor receptor 2 (HER2), has demonstrated pharmacodynamic activity, with stable disease in non–small-cell lung cancer. Combining erlotinib and pertuzumab may enhance antitumor activity. This study aimed to establish the recommended dosing of the erlotinib and pertuzumab combination; assess safety, preliminary efficacy, and pharmacokinetics; and analyze biomarkers. Patients and Methods Fifteen patients with stage IIIb/IV non–small-cell lung cancer who failed chemotherapy were recruited. The patients received erlotinib (days −8 to −1), then combination therapy (21-day cycles for 6 cycles). Pertuzumab was given intravenous at 840 mg, then 420 mg once every three weeks, with erlotinib given daily (100 or 150 mg). Results No dose-limiting toxicities were observed. Adverse events were generally grade 1/2 and manageable. The objective response rate was 20% (3/15 patients; 2 responders had mutant HER1, 1 responder had wild-type HER1), median overall progression-free survival was 9.3 weeks. High HER1, HER2, and HER3 messenger RNA expression correlated with increased progression-free survival. Combination therapy did not affect erlotinib's pharmacokinetics; however, pertuzumab mean exposures (maximum concentration, 231 mg/L; area under the concentration-time curve from 0 to 21 days, 1780 mg*d/L) were slightly higher than in previous studies. Conclusions Combination therapy was well tolerated in patients with good performance status, with encouraging efficacy. A loading dose of pertuzumab 840 mg followed by 420 mg once every three weeks plus daily erlotinib 150 mg appears to be the most appropriate regimen for this combination.