HDAC9 and Thrombocytopenia: Key AEs associated with HDAC inhibitors in patients with B cell lymphomas include grade ≥ 3 fatigue, neutropenia, and thrombocytopenia (which can affect ≥ 30% of patients), and gastrointestinal issues (e.g., diarrhea, dehydration, anorexia) [88, 92].