Development and characterization of the venetoclax-resistant AML model to enable preclinical drug discovery

Acute myeloid leukemia (AML) is an aggressive type of hematological cancer, causing over 100,000 death per year globally. Venetoclax, a BCL-2 antagonist, was approved in 2018 for the treatment of AML in combination with Azacytidine. Through neutralizing BCL-2 function, Venetoclax restores the apoptotic cascade in tumor cells. However, long-term efficacy of Venetoclax is often limited by the development of drug resistance, underscoring the need for preclinical Venetoclax-resistant (Ven-R) tumor models. In this study, we successfully established two Venetoclax-resistant cell lines, Ven-R-MV4-11 and Ven-R-MOLM-13, through chronic exposure to Venetoclax. Compared to the parental cell lines, both resistant cell lines exhibited increased expression of MCL-1, an anti-apoptotic protein that plays a crucial role in Venetoclax resistance. Cell viability assays in these resistant cell lines demonstrated strong synergy between Venetoclax and two MCL-1 inhibitors, AMG-176 and MIK665. In vivo , both Ven-R-MV4-11 and Ven-R-MOLM-13 models showed increased growth rate and substantial resistance to Venetoclax alone and in combination with Azacytidine (standard therapy). Interestingly, the MCL-1 inhibitor, MIK665 effectively overcame the resistance in the Ven-R-MV4-11 tumor model when used in combination with Venetoclax and Azacytidine. In conclusion, we have developed two Venetoclax-resistant AML models, which serve as a promising tool for mechanistic research and drug discovery aimed at overcoming the BCL2 inhibitor resistance.