Pentostatin and rituximab therapy for previously untreated patients with B-cell chronic lymphocytic leukemia.

BACKGROUND

The combination of pentostatin (P), cyclophosphamide (C), and rituximab (R) achieved an overall response (OR) rate >90%, with >40% complete responses (CRs) in patients with untreated chronic lymphocytic leukemia (CLL).

METHODS

To evaluate whether the tolerability of this regimen could be enhanced without sacrificing efficacy, a phase 2 trial was conducted of P and R without C, using a higher P dose (4 mg/m(2)). Among the 33 patients enrolled, 82% were male, the median age was 65 years (9 patients were aged >or=70 years), and 64% were classified as having Rai stage III to IV disease.

RESULTS

The OR rate was 76%, with 9 CRs (27%), 5 nodular partial responses, and 11 partial responses (PRs) reported. At the time of last follow-up, 29 of 33 patients were still alive at a median follow-up of 14 months (range, 1-34.8 months). Four (12%) patients experienced grade 3 or higher hematologic toxicity, and 5 (15%) experienced grade 3 or higher nonhematologic toxicity. Comparison of this trial with the previous PCR trial demonstrated that patients treated with PCR had a higher OR rate (91% vs 76%) and CR rate (41% vs 27%) compared with patients treated with PR. The median treatment-free survival for all accrued patients was notably longer in patients treated with PCR compared with PR (30 months vs 16 months).

CONCLUSIONS

The findings of the current study suggest that increasing the dose of the purine nucleoside analogue does not eliminate the need for cyclophosphamide in chemoimmunotherapy for the treatment of CLL.