Chronic lymphocytic leukemia and hairy-cell leukemia.

In recent years, major advances in our understanding of the biology of the chronic lymphoid leukemias have been accompanied by the emergence of new therapeutic options. Chronic lymphocytic leukemia, the most common of these disorders, appears to be related to a failure of apoptosis, leading to accumulation of functionally abnormal lymphocytes. Fludarabine, a nucleoside analogue that may activate apoptosis, has emerged as the most effective agent for newly diagnosed as well as relapsed patients with chronic lymphocytic leukemia. Nevertheless, few if any patients are cured with this agent. Unique chemotherapeutic and biologic therapies are being explored, and new strategies combining several approaches will likely be established. For patients with hairy-cell leukemia, pentostatin and 2-chlorodeoxyadenosine achieve durable complete remissions in 65% to 85% of patients, with comparable toxicity.