Bolus administration of cladribine in the treatment of Waldenström macroglobulinaemia.

This phase II clinical trial evaluated bolus cladribine as a single agent in Waldenstrom macroglobulinaemia (WM). Cladribine was administered to 20 patients at a dose of 0.12 mg/kg/d by 2 h intravenous infusion for 5 consecutive days at monthly intervals for three courses. Partially responding patients were continued on therapy until maximal response and/or prohibitive toxicity, to a maximum of eight courses. Complete responders were treated with one additional course of cladribine. After a median of three courses of cladribine, all 20 patients were evaluable; one achieved a complete response (CR) (5%) and 10 achieved a partial response (PR) (50%). The median duration of response follow-up was 28 months (range 1-37 months). Four of 7 (57%) untreated and 7/13 (54%) previously treated patients responded. The major toxicity encountered was myelosuppression with 60% of patients demonstrating grade 3 or 4 neutropenia. Non-haematological toxicities included two patients with herpes zoster and two patients with non-melanoma skin cancers. At a median follow-up duration of 20 months, 17 patients remain alive and three have died. We confirm that bolus cladribine is an effective and safe method of drug delivery in WM patients. Recommendations regarding the equivalence of the continuous infusion and bolus methods in untreated patients requires further study. Bolus cladribine is more convenient and less costly than infusional cladribine since it obviates the need for central catheters and infusional devices.