Abstract P29: Zotatifin, the eukaryotic translation initiation factor 4A (eIF4A) inhibitor, synergizes with Venetoclax to inhibit acute myeloid leukemia cell growth

Abstract

Abstract New targeted therapies such as the selective and potent BCL-2 inhibitor Venetoclax have revolutionized the treatment of acute myeloid leukemia (AML). However, due to the cellular heterogeneity of the disease, drug-resistant cell types often emerge and drive relapse. We found that the eukaryotic translation initiation factor 4A (EIF4A) is highly expressed in multiple primitive AML cell types compared to their healthy counterparts, suggesting its potential as a therapeutic target. By unwinding complex structures in the 5’ UTR of transcripts, eIF4A promotes the translation of oncogene transcripts. A first-in-class drug, Zotatifin, inhibits the helicase activity of eIF4A and curtails tumor growth in receptor tyrosine kinase-driven tumors. Zotatifin is currently being evaluated in phase 1/2 trials across multiple solid tumors (NCT04092673). However, its effectiveness in blood cancers such as AML remains unexplored, and it is unknown whether Zotatifin may work synergistically with Venetoclax. Here, we treated AML cell lines in vitro and primary healthy or AML bone marrow ex vivo with Zotatifin or Venetoclax alone and in combination, and demonstrate synergistic killing of AML cells by the combination therapy (ZIP synergy score = 57.0 in MOLM-13, 19.3 in MV4-11, P < 0.0001). Mechanistically, we show that Zotatifin decreases eIF4A and AKT expression, and its combination with Venetoclax drives increased BAK and cleaved BAK expression, as well as increased cleavage of MCL-1 and BCL-2, consistent with drug synergy by convergence on the apoptotic pathway. In pilot colony-forming unit (CFU) assays, we found the combination to be tolerable in healthy CD34+ human hematopoietic stem and progenitor cells (HSPCs). To test drug efficacy in vivo, we generated a patient-derived xenograft (PDX) AML model from a patient who experienced relapse with complex cytogenetics, FLT3 and NPM1 mutations. Only the combination of Zotatifin and Venetoclax but not monotherapies effectively suppressed tumor burden as assessed by human CD45 engraftment in the peripheral blood. Further, the combination of Zotatifin and Venetoclax significantly prolonged survival of xenografted mice (median survival after treatment: vehicle 11 days, Venetoclax 13 days, Zotatifin 15 days, combination 42 days, P = 0.0002). Together, our data indicates that Zotatifin is synergistic with Venetoclax and may represent an effective treatment option for patients who are either primary refractory or have developed resistance to existing Venetoclax-containing regimens. Citation Format: Yoke Seng Lee, Jonathan Good, Noha Awais, Benjamin Eschle, Jenny Noel, Jean Acosta, Erica DePasquale, David Cucchi, Prafulla Gokhale, Fadi Najm, Peter van Galen. Zotatifin, the eukaryotic translation initiation factor 4A (eIF4A) inhibitor, synergizes with Venetoclax to inhibit acute myeloid leukemia cell growth [abstract]. In: Proceedings of the Blood Cancer Discovery Symposium; 2024 Mar 4-6; Boston, MA. Philadelphia (PA): AACR; Blood Cancer Discov 2024;5(2_Suppl):Abstract nr P29.