Citarinostat (ACY-241) is a selective HDAC6 inhibitor being investigated primarily for its potential in cancer therapy. It modulates the acetylation of key proteins involved in cell survival, proliferation, and immune response by targeting HDAC6, which plays a role in the degradation of misfolded proteins and regulation of the heat shock response. One of its main applications is in hematologic malignancies and solid tumors, where it has shown preclinical activity alone and in combination with other agents such as immunotherapies and proteasome inhibitors. By enhancing antigen presentation and reducing immunosuppressive factors, citarinostat may improve the effectiveness of immune checkpoint inhibitors. It is also being explored for its ability to cross the blood-brain barrier, opening potential use in central nervous system cancers or neurodegenerative conditions involving protein aggregation. Clinical development focuses on its favorable safety profile and synergistic potential in combination regimens, particularly in non-Hodgkin lymphoma, multiple myeloma, and non-small cell lung cancer.