Metformin Plus Tyrosine Kinase Inhibitors for Treatment of Patients With Non-small Cell Lung Cancer With EGFR Mutations (METLUNG)

Lung cancer represents the most frequent neoplastic disease worldwide, with an annual incidence of over 2 million cases, which represents 11.6% of all cancer diagnoses. Further, it constitutes the main cause of cancer-related deaths. Among the lung cancer types, non-small cell lung cancer represents 80-85% of cases, and the majority of patients are diagnosed with locally advanced or metastatic disease, and 5-year survival rates remain discouraging in most world regions, ranging from 8-18%.

Advances in molecular biology have led to the discovery of several molecular targets and development of targeted therapy for patients with specific molecular subtypes of NSCLC. One of the most widely studied is the epidermic growth factor receptor (EGFR), which has been long recognized as a key modulator for specific tumor cell functions, and thus it has been used in drug development strategies.

Mutations in the EGFR gene are reported in 15% of all NSCLC cases, though incidence varies widely and in Mexico up to 34% of patients present with tumors with EGFR mutations. Treatment of patients with tumors with these characteristics is based on specific tyrosine kinase inhibitors (TKIs), achieving higher objective response rates and improved progression-free survival (PFS) compared with chemotherapy-based schemes. Nonetheless, despite the initial response, most patients treated with TKIs will eventually develop resistance mechanisms and present progressive disease. Consequently, the development of novel strategies to overcome TKI resistance and improve PFS of patients with NSCLC with epidermic growth factor receptor mutations (EGFRm) is priority.

Up to 30% of patients with NSCLC present with somatic mutations in the liver kinase B1 (LKB1) gene, which acts as a tumor suppressor through inhibition of mammilian target of rapamycin (mTOR). In a study which included 24 patients with LKB1 expression who received treatment with metformin + TKIs, overall survival was improved significantly, and therefore it is important to evaluate LKB1 expression in addition to mutations which could be related with treatment response in patients given metformin plus antineoplastic agents. LKB1 can activate AMP-activated protein kinase (AMPK) signaling through specific phosphorylations at aminoacid residues. AMPK can regulate cell cycle, cell proliferation and cell survival in NSCLC. Recently, the loss of expression of LKB1 has been associated with a reduced activation in AMPK using in vivo models, and increase in tumor necrosis after treatment with bevacizumab. The expression of AMPK has also been evaluated in NSCLC, a study which included 99 samples concluded that increased AMPK expression was associated with worse overall survival. Nonetheless, the association between AMPK expression and metformin treatment has not been ascertained.

Metformin is a biguanide used as treatment for type 2 diabetes. Additionally, several studies have identified a reduced incidence and mortality from diverse neoplasms in patients treated with metformin. In vitro studies have shown that metformin is cytotoxic in lung adenocarcinoma cells, producing a cell cycle arrest at G0 and G1, and it inhibits resistance to TKIs induced by Epithelial-Mesenchymal transition (EMT). Retrospective trials have also provided evidence as to the benefit of metformin in patients undergoing treatment for NSCLC. Several prospective trials have evaluated the concurrent use of metformin plus TKIs for patients with lung adenocarcinoma, though results have been controversial.

This randomized, phase 3 study will evaluate the PFS in patients with NSCLC with EGFR mutations undergoing treatment with TKIs plus placebo vs. TKIs plus metformin.