PRC2 loss of function confers a targetable vulnerability to BET proteins in T-ALL

Blood. 2021 Nov 11;138(19):1855-1869. doi: 10.1182/blood.2020010081.

Abstract

T-cell acute lymphoblastic leukemia (T-ALL) is a group of aggressive hematological cancers with dismal outcomes that are in need of new therapeutic options. Polycomb repressor complex 2 (PRC2) loss-of-function alterations were reported in pediatric T-ALL, yet their clinical relevance and functional consequences remain elusive. Here, we extensively analyzed PRC2 alterations in a large series of 218 adult T-ALL patients. We found that PRC2 genetic lesions are frequent events in T-ALL and are not restricted to early thymic precursor ALL. PRC2 loss of function associates with activating mutations of the IL7R/JAK/STAT pathway. PRC2-altered T-ALL patients respond poorly to prednisone and have low bone marrow blast clearance and persistent minimal residual disease. Furthermore, we identified that PRC2 loss of function profoundly reshapes the genetic and epigenetic landscapes, leading to the reactivation of stem cell programs that cooperate with bromodomain and extraterminal (BET) proteins to sustain T-ALL. This study identifies BET proteins as key mediators of the PRC2 loss of function-induced remodeling. Our data have uncovered a targetable vulnerability to BET inhibition that can be exploited to treat PRC2-altered T-ALL patients.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Animals
  • Antineoplastic Agents, Hormonal / therapeutic use
  • Cell Line, Tumor
  • Epigenesis, Genetic / drug effects
  • Female
  • Gene Expression Regulation, Leukemic* / drug effects
  • Humans
  • Loss of Function Mutation* / drug effects
  • Male
  • Mice
  • Mice, SCID
  • Middle Aged
  • Polycomb Repressive Complex 2 / genetics*
  • Precursor T-Cell Lymphoblastic Leukemia-Lymphoma / drug therapy
  • Precursor T-Cell Lymphoblastic Leukemia-Lymphoma / genetics*
  • Prednisone / therapeutic use
  • Transcription Factors / antagonists & inhibitors
  • Transcription Factors / genetics*
  • Tumor Cells, Cultured
  • Young Adult

Substances

  • Antineoplastic Agents, Hormonal
  • BRD2 protein, human
  • Transcription Factors
  • Polycomb Repressive Complex 2
  • Prednisone