Abstract 6501: Preclinical evidence for synergistic activity of alectinib and everolimus in ALK-positive non-small cell lung cancer

Abstract Introductory Sentence: This study investigates the therapeutic potential of dual alectinib and everolimus inhibition to prolong the clinical benefit of alectinib in ALK-positive non-small cell lung cancer. Pertinent experimental procedures: ALK-rearranged NSCLC cell lines (CUTO8, CUTO9, CUTO29.1, CUTO39, CUTO41, CUTO43, CUTO46) obtained from the University of Colorado; DFCI032 from Dana-Farber; NCI-H2228 and NCI-H3122 from ATCC; and SNU2292 and SNU2535 from Seoul National University were screened using a high-throughput drug-combination platform to identify synergistic interactions between alectinib and a curated library of 1,600 approved and experimental compounds. Functional validation in NCI-H3122 included colony-formation and Glo-Caspase 3/7 apoptosis assays with therapeutically relevant concentrations of everolimus (Cmax and Caverage) plus 100 nM alectinib, ∼ten-fold lower than reported Cmax/Caverage. Apoptotic activation was further confirmed by Western blot for cleaved PARP, cleaved caspase-3, and the pro-survival protein MCL-1. In parallel, ex vivo screening was conducted on ALK167-T-01, an ALK-positive PDX model harboring the p.Leu1196Met ALK mutation. Summary of new unpublished data: High-throughput screening identified a consistent synergistic response to alectinib combined with multiple mTOR inhibitors across all the ALK-rearranged models tested. Synergy was assessed by the Chou-Talalay method, with Cl 1 in most ALK-positive cell lines tested. In NCI-H3122, the combination significantly reduced clonogenic potential (alectinib alone VS combo Caverage; p0.01 and alectinib alone VS combo Cmax; p0.001) and induced apoptosis, evidenced by increased Caspase 3/7 activity (alectinib alone VS combo Caverage; p0.01 and alectinib alone VS combo Cmax; p0.001) and significant PARP and caspase-3 cleavage. Ex vivo PDX screening using ALK167-T-01 with Glo-Caspase 3/7 assays at therapeutically relevant everolimus concentrations plus 100 nM alectinib showed higher apoptosis vs single agents (alectinib alone VS combo Caverage; p0.001 and alectinib alone VS combo Cmax; p0.0001), confirming synergy is not exclusive to sensitive lines. Statement of the conclusions: Dual ALK and mTOR targeting with alectinib and everolimus produces synergistic antitumor activity in vitro and ex vivo, reflected by significantly increased apoptosis vs single agents. These findings support further investigation in in vivo models, including alectinib-sensitive and -resistant tumors. AI disclosure: AI was used for language editing only; content was verified by the authors. Citation Format: Hamadi Madhi, Habib Serhan, Rachel Mercer, Benjamin Levy, Anna Rottinghaus, Liwei Bao, Xu Cheng, Sharon R. Pine, Ross Camidge, Angel Qin, Nathan M. Merrill, Sofia D. Merajver, Matthew B. Soellner. Preclinical evidence for synergistic activity of alectinib and everolimus in ALK-positive non-small cell lung cancer abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 6501.