PROTAC-induced BET protein degradation as a therapy for castration-resistant prostate cancer

Proc Natl Acad Sci U S A. 2016 Jun 28;113(26):7124-9. doi: 10.1073/pnas.1521738113. Epub 2016 Jun 6.

Abstract

Prostate cancer has the second highest incidence among cancers in men worldwide and is the second leading cause of cancer deaths of men in the United States. Although androgen deprivation can initially lead to remission, the disease often progresses to castration-resistant prostate cancer (CRPC), which is still reliant on androgen receptor (AR) signaling and is associated with a poor prognosis. Some success against CRPC has been achieved by drugs that target AR signaling, but secondary resistance invariably emerges, and new therapies are urgently needed. Recently, inhibitors of bromodomain and extra-terminal (BET) family proteins have shown growth-inhibitory activity in preclinical models of CRPC. Here, we demonstrate that ARV-771, a small-molecule pan-BET degrader based on proteolysis-targeting chimera (PROTAC) technology, demonstrates dramatically improved efficacy in cellular models of CRPC as compared with BET inhibition. Unlike BET inhibitors, ARV-771 results in suppression of both AR signaling and AR levels and leads to tumor regression in a CRPC mouse xenograft model. This study is, to our knowledge, the first to demonstrate efficacy with a small-molecule BET degrader in a solid-tumor malignancy and potentially represents an important therapeutic advance in the treatment of CRPC.

Keywords: BET; BRD4; PROTAC; prostate; protein degradation.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Antineoplastic Agents / administration & dosage*
  • Cell Cycle Proteins
  • Cell Line, Tumor
  • Humans
  • Male
  • Mice
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Prostatic Neoplasms, Castration-Resistant / drug therapy*
  • Prostatic Neoplasms, Castration-Resistant / genetics
  • Prostatic Neoplasms, Castration-Resistant / metabolism*
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism*
  • Proteolysis
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism*
  • Receptors, Androgen / genetics
  • Receptors, Androgen / metabolism
  • Signal Transduction / drug effects
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*

Substances

  • Antineoplastic Agents
  • BRD2 protein, human
  • BRD3 protein, human
  • BRD4 protein, human
  • Cell Cycle Proteins
  • Nuclear Proteins
  • RNA-Binding Proteins
  • Receptors, Androgen
  • Transcription Factors
  • Protein Serine-Threonine Kinases