What is the role of cladribine in the treatment of hairy cell leukemia (HCL)?

Updated: Sep 16, 2018
  • Author: Emmanuel C Besa, MD; Chief Editor: Koyamangalath Krishnan, MD, FRCP, FACP  more...
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The first-line therapy for hairy cell leukemia is cladribine, 0.1 mg/kg/d by continuous intravenous infusion for 7 days. The drug can be administered on an outpatient basis with a pump, after placement of a percutaneous intravenous central catheter (PICC). [28, 29, 30]

Growth factors are not routinely given but may be added in patients with febrile neutropenia. Platelet counts usually respond first (in 2-4 weeks), followed by white blood cell counts and neutrophil counts and, finally, hemoglobin levels. Bone marrow biopsy is repeated in 3 months, but minimal residual disease does not need therapy.

With one course of therapy of cladribine, 80% of patients obtain a complete remission (CR), and the remainder obtain a partial remission (PR). Several long-term studies have been reported. Chadha et al reported that although the overall survival rate at 12 years was 87%, the progression-free survival at 12 years was only 54%. [31] In addition, 17% of patients had developed another malignancy during that time.

For greater convenience, some groups have given cladribine as a 2-hour infusion (0.14 mg/kg/d) for 5 days. Zinzani et al reported a CR rate of 81% and a PR rate of 19% using this schedule. [4] The 13-year overall survival rate was 96%, and the relapse-free survival rate was 52%. [4] No randomized study comparing the 24-hour infusional versus the 2-hour infusional schedules is available.

In patients with minimal residual disease following treatment with cladribine, observation is currently the standard therapy. Ravandi et al reported that treatment with rituximab resulted in eradication of minimal residual disease in 11 of 12 patients with residual disease following cladribine therapy. [32]  Whether this treatment alters the natural history of hairy cell leukemia or prevents relapse is unclear.

For patients with relapsed hairy cell leukemia who have previously been treated with splenectomy, interferon, or pentostatin, retreatment with cladribine in the same manner is indicated, especially if their disease had previously responded to cladribine. In patients previously treated with cladribine, response rates of 50% are typical. [33]  In patients with relapsed or refractory hairy cell leukemia who are treated with rituximab, response rates of 50% are reported.

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