Efficacy of a Novel BCL-xL Degrader, DT2216, in Preclinical Models of JAK2-mutated Post-MPN AML.

Acute myeloid leukemia (AML) that evolves from myeloproliferative neoplasm (MPN) is known as post-MPN AML. Current treatments don't significantly extend survival beyond 12 months. BCL-xL has been found to be overexpressed in leucocytes from MPN patients, making it a potential therapeutic target. We investigated the role of BCL-xL in post-MPN AML and tested the efficacy of DT2216, a platelet-sparing BCL-xL proteolysis-targeting chimera (PROTAC), in preclinical models of post-MPN AML. We found that BCL2L1, the gene encoding BCL-xL, is expressed at higher levels in post-MPN AML patients compared to those with de novo AML. Single-cell multi-omics analysis revealed that leukemia cells harboring both MPN-driver and TP53 mutations exhibited higher BCL2L1 expression, elevated scores for leukemia stem cell, megakaryocyte development, and erythroid progenitor than wild-type cells. BH3 profiling confirmed a strong dependence on BCL-xL in post-MPN AML cells. DT2216 alone, or in combination with standard AML/MPN therapies, effectively degraded BCL-xL, reduced the apoptotic threshold, and induced apoptosis in post-MPN AML cells. DT2216 effectively eliminated viable cells in JAK2-mutant AML cell lines, induced pluripotent stem cell-derived hematopoietic progenitor cells (iPSC-HPCs), primary samples, and reduced tumor burden in cell line-derived xenograft model in vivo by degrading BCL-xL. DT2216, either as a single agent or in combination with azacytidine, effectively inhibited the clonogenic potential of CD34+ leukemia cells from post-MPN AML patients. In summary, our data indicate that the survival of post-MPN AML is BCL-xL dependent, and DT2216 may offer therapeutic advantage in this high-risk leukemia subset with limited treatment options.