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Leukemia. 2018 Feb;32(2):343-352. doi: 10.1038/leu.2017.207. Epub 2017 Jun 30.

BET protein proteolysis targeting chimera (PROTAC) exerts potent lethal activity against mantle cell lymphoma cells.

Author information

1
Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
2
Arvinas LLC, New Haven, CT, USA.
3
Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA.
4
Department of Lymphoma/Myeloma, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
5
Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, USA.
6
Department of Chemistry, Yale University, New Haven, CT, USA.
7
Department of Pharmacology, Yale University, New Haven, CT, USA.

Abstract

Bromodomain extraterminal protein (BETP) inhibitors transcriptionally repress oncoproteins and nuclear factor-κB (NF-κB) target genes that undermines the growth and survival of mantle cell lymphoma (MCL) cells. However, BET bromodomain inhibitor (BETi) treatment causes accumulation of BETPs, associated with reversible binding and incomplete inhibition of BRD4 that potentially compromises the activity of BETi in MCL cells. Unlike BETi, BET-PROTACs (proteolysis-targeting chimera) ARV-825 and ARV-771 (Arvinas, Inc.) recruit and utilize an E3-ubiquitin ligase to effectively degrade BETPs in MCL cells. BET-PROTACs induce more apoptosis than BETi of MCL cells, including those resistant to ibrutinib. BET-PROTAC treatment induced more perturbations in the mRNA and protein expressions than BETi, with depletion of c-Myc, CDK4, cyclin D1 and the NF-κB transcriptional targets Bcl-xL, XIAP and BTK, while inducing the levels of HEXIM1, NOXA and CDKN1A/p21. Treatment with ARV-771, which possesses superior pharmacological properties compared with ARV-825, inhibited the in vivo growth and induced greater survival improvement than the BETi OTX015 of immune-depleted mice engrafted with MCL cells. Cotreatment of ARV-771 with ibrutinib or the BCL2 antagonist venetoclax or CDK4/6 inhibitor palbociclib synergistically induced apoptosis of MCL cells. These studies highlight promising and superior preclinical activity of BET-PROTAC than BETi, requiring further in vivo evaluation of BET-PROTAC as a therapy for ibrutinib-sensitive or -resistant MCL.

PMID:
28663582
DOI:
10.1038/leu.2017.207
[Indexed for MEDLINE]

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