HDAC6 (Histone deacetylase 6)

Class

Small molecule, HDAC6-selective inhibitor (oral tablet)

Pathway

Histone deacetylase / epigenetic regulation of T-cell and inflammatory cell function

HDAC6 (histone deacetylase 6) is an enzyme that removes acetyl groups from proteins, thereby altering their shape, stability, or interactions. Unlike most histone deacetylases, which act mainly in the nucleus to control gene transcription by modifying histones, HDAC6 operates largely in the cytoplasm and targets non-histone proteins such as tubulin (a structural protein) and HSP90 (a protein-folding chaperone). Through these substrates, HDAC6 influences cell movement, protein quality control, and, notably, the activity of immune cells, including T lymphocytes and regulatory T cells that help restrain excessive immune responses. Selectively inhibiting HDAC6, rather than broadly inhibiting the histone deacetylase family, is intended to dampen inflammatory and autoimmune signaling while leaving the transcription-regulating class I deacetylases largely undisturbed, since broad inhibition of those enzymes is associated with more systemic toxicity. This selectivity rationale makes HDAC6 inhibitors of interest in autoimmune and inflammatory diseases, where the goal is to recalibrate T-cell function and cytokine output without the broader cytotoxic and hematologic effects seen with pan-HDAC inhibitors historically developed for cancer. The mechanism sits at the intersection of epigenetic regulation and immune cell biology, offering a pathway-specific way to modulate inflammation.