Ten-year follow-up of pentostatin combined with cyclophosphamide, and rituximab in previously untreated indolent B-cell lymphoma.
e19040 Background: Frontline regimens for indolent lymphoma are effective, but patients still suffer from relapse. From 2005 to 2007 we enrolled previously untreated patients on a phase II trial to investigate response rate and efficacy of pentostatin combined with cyclophosphamide and rituximab (PCR). PCR is an effective frontline therapy in chronic lymphocytic leukemia. We report the final analysis with a median follow up of nearly ten years. Methods: Patients were treated with 6 cycles of therapy with additional 3 cycles in case of not attaining a CR/CRu. All patients received Pentostatin (4 mg/m2), Cyclophosphamide (600 mg/m2), and Rituximab (375 mg/m2) on day one and every 21 days. Results: Of the 83 patients, five were considered unevaluable for response, but are included as non-responders in our intent-to-treat analysis. Diagnoses included FL (43.4%), SLL (38.5%), and MZL (18.1%). 78.3% had Ann Arbor stage IV lymphoma and 63.9% had bone marrow (BM) involvement. For all 83 patients, the overall response was 92%, and most toxicity events were hematologic, with grade ≥3 neutropenia in 68 of 509 cycles of chemotherapy administered. Long term toxicity includes secondary malignancies in 14 patients. Two patients developed treatment related MDS/AML and both occurred after additional lines of therapy. PFS at 10 years for FL, MZL, and SLL was 71%, 67% and 15%, respectively. PFS was affected by clinicopathologic characteristics. 10-year PFS rates for those with pretreatment β2M < 2.2 and > 2.2 mg/l were 71 % and 21 % respectively. Patients without BM involvement had 10-year PFS of 72% versus 29% for those with BM involvement. The median OS has not been reached. The overall survival rate was 87% at 5 years and 64% at 10 years. The difference in OS rate was statistically significant based on histology, 94% for FL, 66% for MZL, and 39 % for SLL. Conclusions: Long term follow up confirms that PCR is an effective, robust and tolerable treatment regimen for indolent B-cell lymphomas with 34 of 36 patients with FL alive at 10 years with 27 remaining in remission. Clinical Trial Information NCT00496873 Clinical trial information: NCT00496873.