Breast cancer resistance protein (BCRP) affected acquired resistance to gefitinib in a ''never-smoked'' female patient with advanced non-small cell lung cancer

Summary Development of acquired resistance to gefitinib after an initial good response is common. Recently, it was reported that this acquired resistance is related to a secondary mutation associated with a substitution of threonine by methionine at codon 790 (T790M) of the epidermal growth factor receptor (EGFR) gene. In this report, we present a “never smoking” woman with advanced lung cancer who showed acquired resistance to gefitinib, and analysis of autopsy samples revealed no evidence of EGFR mutations in either exons 18–21 or codon 790, and positive immunostaining for breast cancer resistance protein (BCRP). We describe, for the first time, a case in which expression of BCRP was associated with acquired resistance to gefitinib, independent of EGFR mutations.