LAUSR

e13002 Background: ERBB2 mutation has been found to be an oncogenic driver gene in non-small cell lung cancers (NSCLC) and ERBB2-directed therapies have shown promising results in this unique population, while little is known about ERBB2 fusion association with outcomes of afatinib. The aim of this study was to investigate the efficacy of afatinib in patients with advanced ERBB2 fusion NSCLC. Methods: A multicenter study in China was initiated from February 2014, and NSCLC patients have been enrolled as of December 2018. To determine the frequency of the ERBB2 fusions in NSCLC and other tumors, we analyzed data from 2743 clinical NSCLC cases, each of which had results from next-generation sequencing (NGS)-based 381 genes panel assay, analogous to the index patient. Results: Of this entire cohort, eight (0.29%) patients were identified with an ERBB2 fusion, including TNS4-ERBB2 (1), ERBB2-CD79B (1), IGFBP4-ERBB2 (1), ERBB2-PSMD3 (1), SEZ6-ERBB2 (1), ERBB2-PGAP3 (1), ARL5C-ERBB2 (1) and B3GNTL1-ERBB2 (1). The genes most frequently co-altered in patients with ERBB2 fusions were TP53 (37.50%), CDKN2A (25.00%), RB1 (25.00%) and RBM10 (25.00%). Overall TMB in the ERBB2 fusions was low (median 2.97 mut/Mb). For treatments, 25.00% patients chose afatinib, another patients chose chemotherapy or chemoradiotherapy, and case examples of advanced ERBB2 fusion driven NSCLC patients responding to afatinib were actively being sought thru our database. Conclusions: Patients with advanced ERBB2 fusion NSCLC showed a good outcome of afatinib compared to those with ALK/ ROS1 fusion which response to crizotinib, which strengthen the need for effective ERBB2-targeted drugs in clinical practice.