Co-targeting BCL-XL and BCL-2 by PROTAC 753B eliminates leukemia cells and enhances efficacy of chemotherapy by targeting senescent cells

Haematologica. 2023 Oct 1;108(10):2626-2638. doi: 10.3324/haematol.2022.281915.


BCL-XL and BCL-2 are key anti-apoptotic proteins and validated cancer targets. 753B is a novel BCL-XL/BCL-2 proteolysis targeting chimera (PROTAC) that targets both BCL-XL and BCL-2 to the von Hippel-Lindau (VHL) E3 ligase, leading to BCLX L/BCL-2 ubiquitination and degradation selectively in cells expressing VHL. Because platelets lack VHL expression, 753B spares on-target platelet toxicity caused by the first-generation dual BCL-XL/BCL-2 inhibitor navitoclax (ABT-263). Here, we report pre-clinical single-agent activity of 753B against different leukemia subsets. 753B effectively reduced cell viability and induced dose-dependent degradation of BCL-XL and BCL-2 in a subset of hematopoietic cell lines, acute myeloid leukemia (AML) primary samples, and in vivo patient-derived xenograft AML models. We further demonstrated the senolytic activity of 753B, which enhanced the efficacy of chemotherapy by targeting chemotherapy-induced cellular senescence. These results provide a pre-clinical rationale for the utility of 753B in AML therapy, and suggest that 753B could produce an added therapeutic benefit by overcoming cellular senescence-induced chemoresistance when combined with chemotherapy.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents* / pharmacology
  • Antineoplastic Agents* / therapeutic use
  • Apoptosis
  • Cell Line, Tumor
  • Cellular Senescence
  • Humans
  • Leukemia, Myeloid, Acute* / drug therapy
  • Leukemia, Myeloid, Acute* / genetics
  • Leukemia, Myeloid, Acute* / metabolism
  • Proto-Oncogene Proteins c-bcl-2
  • bcl-X Protein / genetics


  • bcl-X Protein
  • Proto-Oncogene Proteins c-bcl-2
  • Antineoplastic Agents