Comparison of cladribine plus prednisone with chlorambucil plus prednisone in patients with chronic lymphocytic leukemia. Final report of the Polish Adult Leukemia Group (PALG CLL1).

Background: We previously published an early report of a randomized, multicenter trial on the efficacy and toxicity of cladribine (2-CdA) + prednisone (P) compared with chlorambucil (Chl) + P in previously untreated patients with progressive or symptomatic chronic lymphocytic leukemia. Here we present the final report of this study.

Material/methods: Of 229 patients, 126 received 2-CdA+P and 103 Chl+P. Patients with no response or progression after three courses or who relapsed earlier than 12 months after completing one treatment were switched to the other. Patients who relapsed later were retreated with the same schedule as before.

Results: Thirty-three patients were retreated with 2-CdA+P and 19 with Chl+P. Overall response (and complete response) rates were 35% (6%) and 47% (16%), respectively. In 50 patients initially treated with Chl+P and then with 2-CdA+P, complete response (CR) was achieved in 12 (24%) and overall response (OR) in 32 (64%). In 28 patients originally treated with 2-CdA+P and then with Chl+P, CR in 1 (3%, p=0.01) and OR in 6 (21%, p=0.003) were obtained. We found no statistically significant difference in overall survival time in patients treated initially with 2-CdA+P and Chl+P aged 60 years (4.63 and 5.27 years, respectively, p=0.45), 60-70 years (3.29 and 3.14 years, p=0.79), and >70 years (1.53 and 1.93 years, p=0.11).

Conclusions: 2-CdA+P is significantly more effective as a second-line treatment and re-treatment than Chl+P. However, we found a trend to longer survival in elderly patients treated with Chl+P.