Abstract 655: Macrophage mediated resistance to TKI therapy in ALK fusion positive non-small cell lung cancer

Abstract

Abstract Patients with lung cancer bearing driver oncogenes such as epidermal growth factor receptor (EGFR) mutations or anaplastic lymphoma kinase (ALK) fusions, often experience long term disease control on targeted therapy. Despite excellent initial responses, ultimately these tumors develop resistance to targeted therapy. While several cancer cell intrinsic mechanisms of targeted therapy resistance are well known, they do not account for all cases of resistance. Based on our previous observations, we hypothesized components of the tumor microenvironment, specifically monocytes and macrophages, also contribute to the development of targeted therapy resistance. We generated bone marrow derived macrophages from C57BL/6 mice and polarized them to an M0, M1, or M2 phenotype over the course of 6 days. At day 7, cells were plated in fresh media and after 2 days, the conditioned media (CM) was collected. Macrophage polarization was verified via qPCR. Murine cell lines, EA-1, EA-2, and EA-3 are unique, murine lung adenocarcinomas bearing an oncogenic ALK fusion derived from C57BL/6 mice. These murine cell lines were then cultured in the macrophage CM prior to exposure to ALK fusion specific tyrosine kinase inhibitors (TKI), alectinib or crizotinib. We observed that culture in M2-CM resulted in at least a 10-fold increase in alectinib resistance across all 3 murine cell lines when compared to the same cell lines cultured in M1 or M0-CM. We next tested for the activity of known, clinically relevant bypass signaling pathways as mediator of M2-CM protection. Aftatinib, an inhibitor of EGFR and human epidermal growth factor receptor 2 (HER2) family of proteins, did not alter M2-CM protection in the presence of alectinib. M2-CM did not impart TKI resistance to the murine cell lines in the presence of crizotinib, a TKI which inhibits ALK fusion activity and MET receptor tyrosine kinase activity, suggesting bypass signaling through MET drives the M2-CM resistance. Ongoing animal model studies demonstrate a clear role for innate immune cells in decreasing tumor responsiveness to TKI. In summary, our work demonstrates TKI therapy may be modulated by the presence of and interaction with specific immune cells within the tumor microenvironment. These data support exploring macrophage targeting therapies to improve TKI responsiveness. Citation Format: Melanie Mandell, Katherine Priest, Anh Le, Lynn Heasley, Raphael Nemenoff, Erin L. Schenk. Macrophage mediated resistance to TKI therapy in ALK fusion positive non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 655.