The effect of 2-h infusion of 2-chlorodeoxyadenosine (cladribine) with prednisone in previously untreated B-cell chronic lymphocytic leukaemia.

2-Chlorodeoxyadenosine (2-CdA) is a new antimetabolite chemotherapeutic agent active in indolent lymphoid malignancies. In this retrospective study, 69 previously untreated patients with B-cell chronic lymphocytic leukaemia (B-CLL) were treated with 2-CdA administered at a dose of 0.12 mg/kg daily in 2-h intravenous infusion for 5 consecutive days. 45 patients also received prednisone 30 mg/m2 orally each day for 5 days starting with 2-CdA courses. Patients were given 2-6 courses (mean 4.6) of 2-CdA repeated usually at monthly intervals. If a complete response was achieved, no further 2-CdA courses were administered. Guidelines for response were those developed by the NCI Sponsored Working Group. Complete response (CR) was achieved in 26 (38%) and partial response (PR) in 27 (39%) cases, giving an overall response rate of 77%. 16 patients (23%) did not respond to 2-CdA. In the subgroup of 45 patients receiving 2-CdA with prednisone, CR was obtained in 15 (33%) and PR in 20 (44%) patients giving an overall response rate of 78%. CR was achieved in 11 (46%) out of 24 patients treated only with 2-CdA and in 7 cases (29%) PR was observed, giving an objective response rate of 75%. The differences between both subgroups were not statistically significant. However, we observed a relationship between the response and the number of courses of 2-CdA given in patients receiving and those not receiving prednisone. In the subgroup receiving 2-CdA with prednisone, an earlier response to 2-CdA was observed. In this group a response was achieved in 9 (20%) patients after two courses of 2-CdA and in 18 (40%) after four courses. In the subgroup receiving only 2-CdA, 17 (71%) responses were obtained after six cycles.