Analysis of Tumor Heterogeneity Through AXL Activation in Primary Resistance to EGFR Tyrosine Kinase Inhibitors

• DOI: 10.1016/j.jtocrr.2023.100525
• Publication Date: 2023-05-12T02:08:19Z
• Authors: Ryota Nakamura; Hiroyuki Fujii; Tadaaki Yamada; Yohei Matsui; Takeshi Yaoi; Mizuki Honda; Noriyuki Tanaka; Aya Miyagawa-Haya...; Akihiro Yoshimura; Kenji Morimoto; Masahiro Iwasaku; Shinsaku Tokuda; Young Hak Kim; Eiichi Konishi; Kyoko Itoh; Koichi Takayama
• Keywords: EGFR tyrosine kinase inhibitor; Drug resistance; AXL; Non–small cell lung cancer; Neoplasms. Tumors. Oncology. Including cancer and carcinogens; Original Article; Heterogeneity; RC254-282; 3. Good health

EGFR tyrosine kinase inhibitors are standard therapeutic agents for patients with advanced NSCLC harboring EGFR mutations. Nevertheless, some patients exhibit primary resistance to EGFR tyrosine kinase inhibitors in the first-line treatment setting. AXL, a member of the TYRO3, AXL, and MERTK family of receptor tyrosine kinases, is involved in primary resistance to EGFR tyrosine kinase inhibitors in EGFR-mutated NSCLC.We investigated spatial tumor heterogeneity using autopsy specimens and a patient-derived cell line from a patient with EGFR-mutated NSCLC having primary resistance to erlotinib plus ramucirumab.Quantitative polymerase chain reaction analysis revealed that AXL mRNA expression differed at each metastatic site. In addition, AXL expression levels were likely to be negatively correlated with the effectiveness of erlotinib plus ramucirumab therapy. Analysis of a patient-derived cell line established from the left pleural effusion before initiation of treatment revealed that the combination of EGFR tyrosine kinase inhibitors and an AXL inhibitor remarkably inhibited cell viability and increased cell apoptosis in comparison with EGFR tyrosine kinase inhibitor monotherapy or combination therapy of these inhibitors with ramucirumab.Our observations suggest that AXL expression may play a critical role in the progression of spatial tumor heterogeneity and primary resistance to EGFR tyrosine kinase inhibitors in patients with EGFR-mutated NSCLC.