Brief report: EGFR L858M/L861Q cis mutations confer selective sensitivity to afatinib.

Brief report: EGFR L858M/L861Q cis mutations confer selective sensitivity to afatinib.

J Thorac Oncol. 2017 Jan 11;:

Authors: Saxon JA, Sholl LM, Jänne PA

Abstract
INTRODUCTION: Tyrosine kinase inhibitors (TKIs) have been developed to treat patients with epidermal growth factor receptor (EGFR)-mutant lung cancers. However, the therapeutic efficacy of TKIs in patients with uncommon EGFR mutations remains unclear.
METHODS: Next-generation sequencing was performed on a patient's lung adenocarcinoma tumor sample, revealing rare combined in cis (on the same allele) EGFR mutations. Stable Ba/F3 and NIH-3T3 cell lines harboring the mutations were established to investigate the effect of first, second, and third generation EGFR TKIs on cell proliferation by MTS assay and EGFR phosphorylation by Western blotting.
RESULTS: EGFR L858M/L861Q mutations in cis were detected in a non-small cell lung cancer patient's tumor. The patient demonstrated primary resistance to erlotinib and was subsequently treated with afatinib, which caused tumor regression. In in vitro studies, first and third generation TKIs exhibited a decreased capacity to prevent EGFR phosphorylation and inhibit cell proliferation in EGFR L858M/L861Q cells compared to cells harboring the common EGFR L858R point mutation. In contrast, afatinib treatment reduced proliferation and inhibited EGFR phosphorylation in L858M/L861Q and L858R mutant cells at similar concentrations.
CONCLUSIONS: Afatinib may be a beneficial therapeutic option for a subset of lung cancer patients with rare EGFR mutations in their tumors. Understanding how uncommon mutations affect protein structure and TKI binding will be important for identifying effective targeted therapies for these patients.

PMID: 28088511 [PubMed - as supplied by publisher]

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