Isoform-specific histone deacetylase inhibitors: the next step?

Area of Science:

• Biochemistry
• Pharmacology
• Oncology

Background:

• Histone deacetylases (HDACs) are key regulators of gene expression and are targeted for cancer therapy.
• The HDAC family comprises four classes; three are zinc-dependent enzymes targeted by current inhibitors.
• Existing HDAC inhibitors often lack selectivity, leading to dose-limiting toxicities.

Purpose of the Study:

• To review the selectivity and toxicity of HDAC inhibitors in clinical trials.
• To compare pan-HDAC inhibitors with Class I selective compounds.
• To analyze the development and potential clinical utility of isoform-specific HDAC inhibitors.

Main Methods:

• Review of current literature on HDAC inhibitors in clinical development.
• Analysis of selectivity profiles and toxicity data for various HDAC inhibitors.
• Examination of preclinical and clinical data for isoform-specific HDAC inhibitors, focusing on HDAC1, 2, 4, and 8.

Main Results:

• Pan-HDAC inhibitors demonstrate efficacy but are associated with significant toxicities.
• Class I selective HDAC inhibitors show improved toxicity profiles compared to pan-HDAC inhibitors.
• Emerging isoform-specific inhibitors, particularly for HDAC1, 2, 4, and 8, offer potential for targeted cancer therapy with reduced side effects.

Conclusions:

• Isoform-specific HDAC inhibitors represent a promising strategy to enhance therapeutic efficacy and minimize toxicity in cancer treatment.
• Targeting specific HDAC isoforms involved in tumor maintenance could overcome limitations of current broad-spectrum inhibitors.
• Further development and clinical evaluation of isoform-specific HDAC inhibitors are warranted for various neoplastic indications.