Combination therapies to improve the long-term outcome in hairy cell leukemia

Since its first description in 1958, hairy cell leukemia (HCL) had a long period of different unsatisfactory treatments till the early 1980s, when interferon-alfa and subsequently purine analogs (PAs) pentostatin or cladribine, or pentostatin were described to determine durable responses. However, second lines of treatments are very often needed in the life span of patients with HCL and a small minority of patients are refractory and with poor prognosis. These disadvantages have led to test the efficacy of additional compounds, mainly monoclonal antibodies, combined with PAs. The objective of this presentation is to review the current knowledge of combination treatments in HCL. Combination treatments have been used or proposed for different purposes in HCL: to reduce acute toxicity, to improve complete remission (CR) rate, to overcome resistance/refractoriness, to prolong disease-free survival, or to prolong overall survival. The type of patients to be selected for the combinations and the perspectives of combinations of PAs with monoclonal antibodies will also be discussed.