Rituximab and 2-Chlorodeoxyadenosine in Hairy Cell Leukemia as First Line Treatment: A Faster Way to Remission. Report of Five Cases.

Background Hairy-Cell leukaemia (HCL) is an uncommon B-cell chronic lymphoproliferative disorder that accounts for about 2% of all leukaemias. Although the disease is generally indolent in its natural course, the majority of patients requires treatment for life-threatening infections due to pancytopenia or symptomatic splenomegaly. Remarkable progresses have been made in the treatment of HCL. Prior to the advent of nucleoside analogues, which are currently the standard initial treatment, interferon and splenectomy were the most effective therapies. Treatment with purine analogs (PNA) such as 2-chlorodeoxyadenosine (2-CdA) is associated with excellent remission rate and long-term survival. Recently, immunotherapeutic approaches which use monoclonal antibodies, like rituximab, have increased the number of therapeutic options for HCL and offer promising salvage strategies for patients who relapse or who are refractory to treatment with purine analogues. Previously rituximab, used in patients relapsing or refractory to CdA and for elimination of MRD after treatment with PNA, showed hematological CR and good MRD eradication. Patients and treatment We analysed, in a retrospective study, five consecutive patients M/F 4/1, 4 with HCL and one with HCLVariant treated at the diagnosis with one rituximab administration at the dose of 375mg/mq and 2CdA at the dose of 0.14 mg/mq/day s.c. for 5 days. Their median age was 70 years (range 41–71). All patients showed splenomegaly and thrombocytopenia (median platelet count was 65000 with range 49000–88000), four of these presented neutropenia (median count was 435/mmc with range 430–800/mmc) and one patient was severely anemic (Hb < 8 g/dl).

Results None of the patients had severe therapy-related side effects. Four patients showed febrile cutaneous rash, although received prophyilaxis with acyclovir. The median time of recovery for neutrophil count >1500/mmc was 20 days (range 15–38) for platlets count> 100000/mmc was 21days (12–21), and hemoglobin level> 8g/dl was 31.5 days(27–36). Our median follow up at today was 264 days(range 40–570). At this time all patients are in hematological and morphologic complete remission.

Conclusions The use of Rituximab together with 2CDA in first line therapy is safe and feasible. Moreover when Rituximab is used in such setting, median time of recovery in neutrophils and platelets count is significatively shorter than that obtained after therapy with 2CdA alone (8 and 4 weeks respectively). A longer follow-up is needed to evaluate the long-term results of the treatment.