LAUSR

9065Background: BRG is a potent and selective ALK inhibitor with preclinical and clinical activity against wild-type ALK and a broad range of mutants associated with clinical CRZ resistance, including G1202R. Herein we examine the association between BRG efficacy and ALK mutation status using plasma specimens from the initiation of BRG treatment (baseline [BL]) and the end of BRG treatment (EOT) in CRZ-resistant ALK+ NSCLC pts enrolled in the BRG Ph1/2 or pivotal Ph2 (ALTA) trials. Methods: Plasma samples were analyzed using the Resolution Bioscience ctDx Lung Panel v3.0. BRG activity was described using the confirmed objective response rate (cORR) (RECIST v1.1). Data are reported as of May 31, 2016 for the Ph1/2 (NCT01449461) and ALTA (NCT02094573) trials. Results: Of 291 CRZ-resistant ALK+ NSCLC pts enrolled in the Ph1/2 (N = 69) and ALTA (N = 222) trials, evaluable plasma samples were obtained from 67 pts at BL. cORR to BRG in these pts was 49% (33/67). An ALK fusion was detected in plasma in 45% (30/6...