A multicenter, open-label phase II study of metformin with erlotinib in second-line therapy of stage IV non-small-cell lung cancer patients: treatment rationale and protocol dynamics of the METAL trial.

We present the rationale and study design of the METAL (METformin in Advanced Lung cancer) trial (EudraCT number: 2014-000349-59), a multicenter, open label phase II study, designed to evaluate the safety and activity of metformin combined with erlotinib as second-line therapy in patients with stage IV non-small-cell lung cancer. This is a 2-part trial, consisting of a safety run-in part followed by a phase II part. The primary end point for the first part is the maximum tolerated dose and the identification of the recommended phase II dose of metformin in combination with erlotinib. Secondary end points are the study of pharmacokinetics and the antitumor activity evaluation of the experimental combination. The primary end point of part II is the time to disease progression with the combination, and antitumor activity as a secondary end point. Based on the statistical design, we plan to enroll approximately 60 patients.