Overcoming resistance to EGFR tyrosine kinase inhibitors in lung cancer, focusing on non-T790M mechanisms

ABSTRACT

Introduction: despite initial dramatic efficacy of EGFR tyrosine kinase inhibitors (TKIs) in EGFR-mutant lung cancer patients, emergence of acquired resistance is almost inevitable. The EGFR T790M secondary mutation that accounts for ~50% of resistance is now treatable with osimertinib. However, for the remaining 50% of patients who develop resistance mechanisms other than T790M mutation, cytotoxic chemotherapies are still the standard of care and novel treatment strategies are urgently needed.

Areas covered: In this review, we discuss current experimental and clinical evidence to develop better treatment strategies to overcome or prevent acquired resistance to EGFR-TKIs in lung cancers, focusing on non-T790M mechanisms.

Expert commentary: There are numerous non-T790M resistant mechanisms to EGFR-TKIs, and therefore, strategies that can be applied to many of these resistance mechanisms may be reasonable and useful in clinical practice. Although the combination of cytotoxic chemotherapy plus an EGFR-TKI has proved to be detrimental following front-line EGFR-TKI treatment failure, promising experimental and/or early clinical data have been reported for the combination of bevacizumab or anti-EGFR monoclonal antibody plus EGFR-TKIs. Upfront polytherapy, which co-targets potential resistance mechanisms or other important signaling for EGFR-mutant lung cancer cells, is also a promising strategy.

KEYWORDS:

• Non-small cell lung cancers (NSCLCs)
• EGFR mutation
• acquired resistance
• resistance mechanisms
• molecular targeted therapy
• cytotoxic chemotherapy
• combination therapy
• upfront polytherapy
• tumor heterogeneity

Declaration of interest

T Mitsudomi has received honoraria from AstraZeneca, Chugai, Boehringer-Ingelheim, Pfizer and Roche; has received compensation from AstraZeneca, Chugai, Boehringer-Ingelheim, Pfizer, Roche and Clovis Oncology for participating in advisory boards; and has received research funding (through Kindai University Faculty of Medicine) from AstraZeneca and Chugai. FR Hirsch has received compensation from Genentech/Roche, Pfizer, BMS, Lilly, Merck and Ventana/Roche for participating in advisory boards; and has received research funding (through the University of Colorado) from Genentech/Roche, BMS, Lilly, Bayer, Amgen and Ventana/Roche. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Additional information

Funding

This study was supported by a grant from the International Association for the Study of Lung Cancer, Young Investigator Award to K Suda (2015 – 2017).