Long-term outcome of hairy cell leukemia treated with 2-chlorodeoxyadenosine

The long-term results of both pretreated and previously untreated patients with hairy cell leukemia (HCL) using uniformly a single 7-day course of 2-chlorodeoxyadenosine (2-CdA) by continuous infusion are reported. In addition, the probability of obtaining another response with this drug in patients who relapsed after 2-CdA treatment will be addressed. Forty-two consecutive patients (32 men, 10 women) with a median age of 56 years (range 32-75) at the time of initiation of 2-CdA treatment were analyzed. Ten patients were pretreated with either splenectomy (n=6) or interferon a (n=8) or deoxycoformycin (dCF) (n=3) or with all procedures in sequence. Two patients who did not respond to dCF did respond to 2-CdA. Median time to start of 2-CdA treatment of the ten pretreated patients was 47 months (10-160); 41 of the 42 (98%) achieved CR, and one patient reached a good partial response with a single cycle of 2-CdA. Ten of the 42 patients had no toxicities at all. Toxicities (WHO grades I-IV) were mainly of grades I and II; in one patient with a preexisting brain injury grade III neurotoxicity was seen, and one patient suffered a grade-IV infectious complication. Bone marrow biopsies were performed at the time of recovery of hematopoiesis, thereafter at 2- to 3-month intervals, then at 6 months, and finally annually in all 42 patients. Median follow-up is 32 months (2-72). Disease-free survival from start of 2-CdA treatment is 75% at 6 years; 6/42 patients relapsed. Three of these patients were treated with 2-CdA again. All three patients reached another CR (+1, +2, +13). Four of the 42 patients had a second malignancy (carcinomas of the bladder, breast, cervix, prostate gland) before receiving 2-CdA. One patient died in CR due to the second malignancy. 2-CdA is a safe and effective treatment of HCL, inducing complete remissions in the majority of patients with only a single cycle of 2-CdA and a paucity of toxicities. Responses are durable and long lasting. Patients relapsing following a treatment with 2-CdA seem to respond to this drug again.