Nature Communications (Mar 2024)

Development and crystal structures of a potent second-generation dual degrader of BCL-2 and BCL-xL

  • Digant Nayak,
  • Dongwen Lv,
  • Yaxia Yuan,
  • Peiyi Zhang,
  • Wanyi Hu,
  • Anindita Nayak,
  • Eliza A. Ruben,
  • Zongyang Lv,
  • Patrick Sung,
  • Robert Hromas,
  • Guangrong Zheng,
  • Daohong Zhou,
  • Shaun K. Olsen

DOI
https://doi.org/10.1038/s41467-024-46922-4
Journal volume & issue
Vol. 15, no. 1
pp. 1 – 17

Abstract

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Abstract Overexpression of BCL-xL and BCL-2 play key roles in tumorigenesis and cancer drug resistance. Advances in PROTAC technology facilitated recent development of the first BCL-xL/BCL-2 dual degrader, 753b, a VHL-based degrader with improved potency and reduced toxicity compared to previous small molecule inhibitors. Here, we determine crystal structures of VHL/753b/BCL-xL and VHL/753b/BCL-2 ternary complexes. The two ternary complexes exhibit markedly different architectures that are accompanied by distinct networks of interactions at the VHL/753b-linker/target interfaces. The importance of these interfacial contacts is validated via functional analysis and informed subsequent rational and structure-guided design focused on the 753b linker and BCL-2/BCL-xL warhead. This results in the design of a degrader, WH244, with enhanced potency to degrade BCL-xL/BCL-2 in cells. Using biophysical assays followed by in cell activities, we are able to explain the enhanced target degradation of BCL-xL/BCL-2 in cells. Most PROTACs are empirically designed and lack structural studies, making it challenging to understand their modes of action and specificity. Our work presents a streamlined approach that combines rational design and structure-based insights backed with cell-based studies to develop effective PROTAC-based cancer therapeutics.