Treatment of hairy cell leukemia with deoxycoformycin (YK-176). The Deoxycoformycin (YK-176) Study Group

Eleven patients with hairy cell leukemia (HCL) were treated with YK-176 (2'-deoxycoformycin) at a dose of 5 mg/m2 by intravenous injection every week or every other week. Patients received a median of eight (range 4-19) injections of YK-176. Five patients had previously been untreated, four of whom had massive splenomegaly. Six patients had previously been treated, four with interferon-alpha (IFN-alpha) or IFN-alpha and chemotherapy and two with prednisolone. Two patients had had splenectomies. Five patients achieved complete remission (CR) and six, partial remission (PR) according to WHO criteria (remission rate 100%, 95% confidence interval (CI) 74-100%). All six neutropenic patients recovered > 1,500/microliters neutrophils, six of seven anemic patients recovered > 12.0 g/dl hemoglobin and five of nine thrombocytopenic patients recovered > 100,000/microliters platelets following the treatment. According to the response criteria for HLC, five patients achieved CR, two PR and four minor response. The overall remission (CR + PR) rate was 64% (95% CI 35-85%). The CR and PR have lasted from > 30 to > 718 days (median, > 281 days) so far with no relapses. Of four patients previously treated with IFN-alpha, two achieved CR and one, PR. All patients were alive with a median survival time of > 290 days from treatment (range > 50- > 763 days). The treatment was generally well tolerated. Mild to moderate nausea, vomiting, appetite loss and general fatigue were experienced in two patients, skin rash in one and a transient fever in three. YK-176 was a highly active agent in the treatment of HCL.