Cloretazine (VNP40101M), a novel sulfonylhydrazine alkylating agent, in patients age 60 years or older with previously untreated acute myeloid leukemia

Purpose Cloretazine (VNP40101M) is a sulfonylhydrazine alkylating agent with significant antileukemia activity. A multicenter phase II study of cloretazine was conducted in patients 60 years of age or older with previously untreated acute myeloid leukemia (AML) or high-risk myelodysplastic syndrome (MDS). Patients and Methods Cloretazine 600 mg/m(2) was administered as a single intravenous infusion. Patients were stratified by age, performance score, cytogenetic risk category, type of AML, and comorbidity. Results One hundred four patients, median age 72 years (range, 60 to 84 years), were treated on study. Performance status was 2 in 31 patients (30%) and no patient had a favorable karyotype. Forty-seven patients (45%) had cardiac disease, 25 patients (24%) had hepatic disease, and 19 patients (18%) had pulmonary disease, defined as per the Hematopoietic Cell Transplantation Specific Comorbidity Index, at study entry. The overall response rate was 32%, with 29 patients (28%) achieving complete response (CR) and four patients (4%) achieving CR with incomplete platelet recovery. Response rates in 44 de novo AML patients, 45 secondary AML patients, and 15 high-risk MDS patients were 50%, 11%, and 40%, respectively. Response by cytogenetic risk category was 39% in 56 patients with intermediate cytogenetic risk and 24% in 46 patients with unfavorable cytogenetic risk. Nineteen (18%) patients died within 30 days of receiving cloretazine therapy. Median overall survival was 94 days, with a 1-year survival of 14%; the median duration of survival was 147 days, with a 1-year survival of 28% for those who achieved CR. Conclusion Cloretazine has significant activity and modest extramedullary toxicity in elderly patients with AML or high-risk MDS. Response rates remain consistent despite increasing age and comorbidity.