Abstract 6794: Elucidating mechanisms of cancer cell persistence to lorlatinib in ALK positive NSCLC

Abstract ALK fusion-positive lung cancers exhibit deep and durable responses to ALK tyrosine kinase inhibitors (TKIs), however the emergence of acquired drug resistance is inevitable. Current targeted therapies are insufficient to eliminate all cancer cells within a tumor. So called drug tolerant “persister” cells (DTPCs) evade initial treatment, subsequently evolve mechanisms of acquired resistance, and drive disease relapse. Currently, our understanding of the underlying mechanisms driving DTPC survival and evolution in ALK+ fusion NSCLC, especially during treatment with the most advanced ALK lorlatinib, remains incomplete. To identify mechanisms and therapeutic vulnerabilities of DTPC survival in ALK+ NSCLC, we performed bulk and single-cell RNA-seq and ATAC-seq on ALK+ NSCLC patient-derived cell lines and PDX tumors before, during and after treatment with lorlatinib. Tumors exhibited robust initial responses to lorlatinib (> 50% of tumor reduction) followed by a stable residual disease phase and in some cases tumor regrowth after extended treatment, mimicking clinical treatment trajectories. Transcriptomic analysis revealed progressive upregulation of MAPK pathway signaling in DTPC cells in residual tumors and resistant cells in relapsing tumors. Furthermore, we discovered a sub-population of cells with stem-like features present in untreated and residual tumors, potentially representing a pre-existing cell state poised to evade lorlatinib treatment. Finally, we identified several tumor surface proteins upregulated in residual and relapsing tumors that could serve as potential targets for antibody drug conjugate therapies. These results reveal mechanisms driving survival and evolution of DTPCs and identify potential therapeutic targets to prevent resistance of ALK+ NSCLCs to lorlatinib. Citation Format: Toshio Fujino, Darlan C. Minussi, Christina L. Anastasia, Emily Hensley, Satoshi Yoda, Mari Mino-Kenudson, Wei Ping, Katya Marjon, Xinmeng J. Mu, Marco Maruggi, Aaron N. Hata. Elucidating mechanisms of cancer cell persistence to lorlatinib in ALK positive NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6794.