2-Chlorodeoxyadenosine (Cladribine) in the treatment of patients with chronic lymphocytic leukemia 55 years old and younger.

The aim of the study was to determine the effectiveness of 2-chlorodeoxyadenosine (2-CdA) administered in 2-h i.v. infusions in the treatment of B cell chronic lymphocytic leukemia (B-CLL) in patients 55 years old and younger. One hundred and thirteen patients received three to 10 courses of 2-CdA administered at a dose of 0.12 mg/kg daily for 5 consecutive days. Sixty-seven patients were previously treated with chlorambucil and prednisone, COP and some of them also with CHOP, and 46 were untreated. Complete remission (CR) was achieved in 21 (18.6%) (19 in untreated and two in previously treated) patients and partial response (PR) in 38 (33.6%) (23 and 15, respectively) giving an overall response rate in 52.2%. The differences in CR and overall response rate between previously treated and untreated patients were statistically significant (P = 0.001). Surface immunophenotyping by flow cytometry using dual-color staining on the peripheral blood and/or bone marrow was performed in 38 patients who responded to 2-CdA therapy. Residual disease had been demonstrated in five out of 17 (29.4%) patients who were in CR and in all 21 investigated PR patients. 2-CdA-induced thrombocytopenia occurred in 24 (35.8%) of previously treated and in 13 (28.3%) previously untreated patients (P = NS). Neutropenia was observed in eight (11.9%) and in five (10.9%) patients, respectively (P = NS). Severe infections, including pneumonia and sepsis, occurred more often in previously treated (44.8%) than untreated patients (26.1%) (P < 0.05). Twenty-seven (23.9%) patients died, 11 because of infections, five because of drug-related thrombocytopenia and hemorrhage, one because of second malignancy and eight because of disease progression. In conclusion, our results indicate that 2-CdA is an effective agent in younger patients with B-CLL, especially used as a first line therapy.