Long-term outcome with pentostatin treatment in hairy cell leukemia patients. A French retrospective study of 238 patients

With the introduction of new drugs such as alpha-interferon (IFN) and purine analogs, the management of hairy cell leukemia (HCL) patients has changed. However, deoxycoformycin (DCF) produced higher complete remission rates than IFN. The current study was undertaken to provide long-term data on duration of overall survival (OS) and disease-free survival (DFS) and incidence of subsequent malignancies. We retrospectively analyzed the data of patients treated with DCF (4 mg/m(2)/day, every 2 weeks) from 39 French centers. In 84 of 238 included patients, DCF was the first-line therapy. Pretreatment variables influencing the achievement of complete remission, DFS, and OS were identified by multivariate analysis. Two hundred and thirty-eight patients received a median of nine cycles (range, 1-19 cycles). A complete remission was obtained in 182 of 230 evaluable patients (79%) and a partial response was obtained in 38 patients, for an overall response rate of 95.6%. In the multivariate analysis hemoglobin level less than 100 g/l and leukocytes less than 2 x 10(9)/l were parameters adversely influencing complete remission achievement. With a median follow-up of 63.5 months (range, 0.39-138.4 months), disease recurrence was observed in 34 of 220 responding patients (15%). The estimated 5-years and 10-years DFS was 88.1 % and 68.8%, respectively. Hemoglobin level less than 100 g/l and leukocytes less than 2 x 10(9)/l were the pre-treatment variables associated with a shorter DFS. The estimated 5-year and 10-year OS were 89.4% and 88.7%, respectively. Hemoglobin level less than 100 g/l, leukocytes less than 2 x 10(9)/l, and adenopathy were significant factors of reduced survival. Hematologic toxicity was the main side-effect, followed by infection and emesis. During the period of follow-up, 18 patients developed second cancer, but the standardized incidence ratio was 0.95. Pentostatin is a highly effective regimen for hairy cell leukemia that produces durable complete responses. Toxicity of DCF is acceptable. Subsequent malignancies do not appear to be increase with pentostatin treatment.