Clinical trials in hairy cell leukemia. Current status and future directions.

During the past 5 years, clinical trials in hairy cell leukemia have shown dramatic activity for alpha-interferon and 2'-deoxycoformycin (pentostatin). Responses can be induced in more than 80% of patients using either agent, although a greater number of complete pathologic remissions may be achieved with deoxycoformycin. Despite interesting preliminary data, the optimal dose, schedule, treatment duration, and impact of therapy on survival are unknown. Clinical trials comparing efficacy and toxicity of alpha-interferon and deoxycoformycin, the extent of cross-resistance, and relationship of activity to previous splenectomy are in progress. Additional studies are testing combinations of these agents. Although interferon is commercially available for treating hairy cell leukemia, considering such therapy routine is counterproductive. Long-term clinical trials of interferon and deoxycoformycin are essential to advance our biologic knowledge of this rare disease, and to ensure optimal therapy for a potentially curable malignancy.