Pentostatin, Cyclophosphamide, and Rituximab (PCR) Achieve High Response Rates in Indolent B-Cell Lyphoma without Prolonged Myelosuppression

Background: The addition of rituximab to combination chemotherapy has improved treatment outcomes of indolent lymphomas. Combination therapy with purine analogs, akylating agents, and monoclonal antibodies is a promising approach for treating indolent B-cell lymphoma. Nucleoside analog-based regimens selectively target lymphoid cells, making them attractive drugs for lymphoid cancers. Pentostatin is a nucleoside analog that compared with other nucleoside analogs is reported to have less bone marrow cell toxicity. The combination of pentostatin, cyclophosphamide, and rituximab (PCR) is an effective regimen for relapsed chronic lymphocytic leukemia.

Methods:In this study, we examined the efficacy of pentostatin, cyclophosphamide, and rituximab for the treatment of B-cell lymphoma. Pentostatin (4 mg/m2), cyclophosphamide (600 mg/m2), and rituximab (375 mg/m2) were given on day 1 of a 21-day cycle with planned 6 or 9 cycles and restaging after every 3 cycles. Patients received prophylaxis with acyclovir 400 mg/po bid and trimethoprim-sulfamethoxazole 3 times per week. Small lymphocytic lymphoma/chronic lymphocytic leukemia (SLL/CLL) tissues were stained for ZAP70 protein.

Results: At the time of abstract submission, 80 patients with a median age was 60 years were treated, 43 patients with follicular lymphoma, 27 with SLL/CLL, and 9 with mucosa-associated lymphoid tissue. We observed an overall response of 77 out of 80 (96%), CR/CRu in 65 out of 80 (81%), PR in 12 out of 80 (15%), and mixed response or progression in 3 out of 80 (4%). Neutropenia (49% < 1000/uL), thrombocytopenia (2% < 100,000/uL), nausea (15% grade 3), fatigue (37% grade 3 and 4), and muscle pain (21% grade 3) was observed. ZAP70 staining and response will be reported. Two patients experienced prolonged pancytopenia that resolved and no cases of myelodysplasia were observed.

Conclusions: PCR therapy is an effective regimen in indolent B cell lymphoma with tolerable toxicity.