CMET-30. BRAIN METASTASES FROM EGFR-MUTATED NSCLC WHICH HAD ACQUIRED RESISTANCE TO EGFR-TKI. ~LESS-FREQUENT T790M AND PRESERVED RESPONSE TO OTHER TKIs~

摘要

BACKGROUNDDespite the favorable response, most brain metastases (MBs) acquire resistance to TKIs. T790M is the most common mechanism and accounts for approximately half of acquired resistance to TKIs. The aim of this study is to clarify the role of T790M in the acquired resistance of BMs, and optimal treatment for BMs progressed after TKI. METHOD: Upfront TKI was performed for BMs from EGFR-mutated NSCLC, and TKI was changed at progression. Gefitinib, erlotinib, afatinib and osimertinib were used and the selection of these TKIs were owing to the physicians’ decision. During the disease course, re-biopsies of progressed diseases were performed to verify mutations of EGFR, and the incidences of T790M were compared among the organs biopsied. The time to CNS-progression (TCP) were evaluated for each TKI.