Abstract 5991: Improved venetoclax therapy by a novel conjugate with artemisinin by NOXA-mediated reduction of Mcl-1 and cyclin D1 protein in myeloid leukemia cells

Abstract Evasion of apoptosis is crucial for the growth, survival and chemoresistance of myeloid leukemia. The Bcl-2 selective inhibitor venetoclax is the only apoptosis inducer approved for clinical use. Venetoclax in combination with hypomethylating agents or low-dose cytarabine has now become the standard care for elderly AML patients. However, a sizeable fraction of patients are either refractory to venetoclax combination therapy or ultimately relapse. High or induced expression of Mcl-1 and Bcl-xL mediates venetoclax resistance. Previously we reported that artemisinin enhances venetoclax apoptosis induction by degrading Mcl-1 through NOXA induction. We designed a novel conjugate A1 of venetoclax with dihydroartemisinin. A1 shows dual functions of inhibiting Bcl-2 and inducing NOXA. A1 treatment releases Bim from both Bcl-2 and Mcl-1, further degrades Mcl-1 protein, and presents ten-fold stronger apoptotic induction ability in venetoclax insensitive cells. Acquired increase of Mcl-1 protein was observed in venetoclax resistant MOLM-13/VEN cells, which are sensitive to A1-induced apoptosis. In Bcl-xL expressing venetoclax refractory leukemia cells A1 obtains a new mechanism of inhibiting cell cycling by downregulating cyclin D1 through a new NOXA/cyclin D1 cascade, mediated through the endoperoxide moiety of artemisinin and intracellular iron, independent of Bcl-2 inhibition. We reveal a new compound A1 overcoming venetoclax resistance by NOXA-mediated degradation of Mcl-1 and cyclin D1 protein. Citation Format: Jingyi Zhang, Zhenwei Zhang, Samuel Waxman, Linxiang Zhao, Yongkui Jing. Improved venetoclax therapy by a novel conjugate with artemisinin by NOXA-mediated reduction of Mcl-1 and cyclin D1 protein in myeloid leukemia cells 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 5991.