Tolerability, pharmacodynamics, and pharmacokinetics studies of depsipeptide (Romidepsin) in patients with acute myelogenous leukemia or advanced myelodysplastic syndromes

Purpose: Epigenetic modulation of gene expression plays an important role in cancer, including leukemia. Furthermore, histone deacetylase inhibitors may induce the reexpression or repression of genes critical for normal hematopoiesis. The purpose of this study was to evaluate the toxicity, pharmacokinetic profile, and selected pharmacodynamic properties of the histone deacetylase inhibitor depsipeptide in patients with myelodysplastic syndromes (MDS) or acute myelogenous leukemia (AML). Experimental Design: Depsipeptide was administered to MDS or AML patients at a (solid tumor) phase I dose of 18 mg/m² i.v. on days 1 and 5 every 3 weeks. Toxicities and clinical activity were monitored and pharmacokinetic and pharmacodynamic studies were done. Results: Twelve patients (nine with AML, three with MDS) received one to five cycles of depsipeptide. The most common grade 3/4 toxicities were febrile neutropenia/infection (five patients), neutropenia/thrombocytopenia (nine patients), nausea (nine patients), and asymptomatic hypophosphatemia (three patients). No clinically significant cardiac toxicity was observed. The best response of 11 assessed patients was one complete remission in a patient with AML, stable disease in six patients, and progression of disease in four patients. Exploratory laboratory studies showed modest but rapid increases in apoptosis and changes in myeloid maturation marker expression. Histone H3 and H4 acetylation levels were evaluated in five patients; no consistent changes were observed. Conclusion: Depsipeptide therapy can be administered with acceptable short-term toxicity. However, gastrointestinal symptoms and fatigue seem to be treatment-limiting after multiple cycles. Depsipeptide monotherapy has limited clinical activity in unselected AML/MDS patients.