Abstract 7191: Targeting IGF1R/INSR pathway with approved ALK inhibitors inhibits AKT signaling and overcomes proteasome inhibitor resistance in multiple myeloma

Abstract Background: Resistance to proteasome inhibitors (PI) bortezomib (BTZ) and carfilzomib (CFZ) is a major obstacle to the successful treatment of multiple myeloma (MM) ; thus, identification of novel therapeutic options is an unmet medical need. ALK inhibitors have been shown to exhibit anti-MM activity in monotherapy or in combination with CFZ. Our data showed that MM cells were negative for ALK; thus, we aimed to identify the mechanism of action of the ALK inhibitor ceritinib in MM cells and the mechanism of synergy between ceritinib and CFZ. Methods: A set of PI-naïve and PI-resistant MM cells was used in this study. Genome-wide CRISPR/Cas9-based screening using the Brunello library was performed in the AMO-1 cell line. Kinase inhibitor selectivity data were retrieved from ChEMBL, v30 database. RNA sequencing was used to determine expression changes after treatment, and RNA-seq data from patients included in the CoMMpass study were analyzed. Western blotting was performed to assess the levels of total and phosphorylated protein. Unbiased LC-MS/MS was performed to determine the effects of ceritinib and CFZ on the intracellular metabolites. An in vivo mouse model based on the orthotopic injection of AMO-BTZ cells into the femur of NSG mice was used to determine the effect of the drug combination in vivo. Results: Among approved ALK inhibitors, ceritinib has been identified as the most synergistic cytotoxic combination with CFZ in PI-naïve and PI-resistant MM cells. An in silico search of the ChEMBL database identified InsR and IGF1R as receptor tyrosine kinase that are inhibited by ceritinib. PI-naïve, PI-resistant cell lines, as well as MM patients were negative for ALK, but positive for InsR and IGF1R expression. CRISPR/Cas9-screening identified genes involved in the negative regulation of mTORC signaling (DDIT4, NPRL2/3, TSC1/2) and the transcription factor FOXO1 as the major resistance candidates to ceritinib. Subsequently, FOXO1 inhibition using a selective chemical inhibitor protected the cells from ceritinib-induced cytotoxicity. Next, ceritinib inhibited mTORC signaling and induced the expression of genes related to cell cycle arrest, which are downstream of FOXO1. Likewise, ceritinib, by targeting the InsR/IGF1R, impaired purine-pyrimidine and amino acid homeostasis, suggesting metabolic and proliferation shut-down and amino acid starvation due to downstream mTORC and Akt inhibition and FOXO1 induction. The combination of ceritinib and CFZ was superior to CFZ in PI-resistant MM in vivo and showed strong synergistic cytotoxicity in primary cells from MM patients progressing under or after PI-containing therapy. Conclusion: Ceritinib, an FDA-approved drug, overcomes PI resistance in MM by inhibiting InsR/IGF1R and downstream Akt signaling. Therefore, ceritinib is a promising treatment option for PI-resistant MM. Supported by the project National Institute for Cancer Research (Programme EXCELES, ID Project No. LX22NPO5102) - Funded by the European Union - Next Generation EU. Citation Format: Andrej Besse, Tiberiu Totu, Marianne Kraus, Anthonius P. Janssen, Jana Veprkova, Max Mendez Lopez, Ondrej Slaby, Marija Buljan, Mario van der Stelt, Christoph Driessen, Lenka Besse. Targeting IGF1R/INSR pathway with approved ALK inhibitors inhibits AKT signaling and overcomes proteasome inhibitor resistance in multiple myeloma abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 7191.