Results of a Nonrandomized, Open-Label, Phase II Study of Combined Gemcitabine, Mitoxantrone, and Rituximab in Relapsed or Refractory Mantle Cell Lymphoma.

Mantle cell lymphoma (MCL) is an aggressive type of B-cell non-Hodgkin’s lymphoma that usually presents as disseminated disease. Prognosis is poor, and responses to chemotherapy are less durable than those achieved in other types of lymphoma. New treatment options are desperately needed. Gemcitabine has shown activity in MCL as a single agent. In addition, the combination of mitoxantrone and rituximab has also been shown to be active in MCL. However, the use of these drugs in combination has not been evaluated in the treatment of MCL. The primary objective of this study was to determine the efficacy of gemcitabine+mitoxantrone+rituximab in relapsed or refractory MCL; secondary objectives were duration of response, survival at 1-year, progression-free survival (PFS), and toxicity, especially myelotoxicity. Sixteen patients were enrolled between April 2005 and December 2006, and only 15 were evaluable due to one patient’s withdrawal of consent. Patients received gemcitabine 900 mg/m² IV (30–60 min infusion), mitoxantrone 10 mg/m² IV (5–10 min infusion), and rituximab 375 mg/m² IV on Day 1 (max 400 mg/hr). Patients also received gemcitabine 900 mg/m² on Day 8 of the 21-day cycle. Medication was administered in the following order: gemcitabine→mitoxantrone→rituximab. Patients were to be treated for a maximum of 8 cycles or until the patient had evidence of a response, progressive disease, or intolerable toxicity. The median patient age was 74 years, 100% were white, and 69% were male. Of all patients, 86% had Stage IV MCL at baseline. Patients received a median of 6 cycles (range, 3 – 8). Efficacy results for the evaluable population are CR 13%, PR 27%, PD 13%, and SD 47%. Median PFS was 8.72 months (range, 1.84 – 23.49); median overall survival was 10.03 months (range, 2.50 – 23.49). Grade 3–4 treatment related toxicities reported in >1 patient were neutropenia (93%), leukopenia or thrombocytopenia (53% each), anemia (20%), and asthenia (13%). 60% of patients are currently alive as of July 2007; 9 patients discontinued study treatment due to disease progression (13%), toxicity (27%), MD request (7%), or withdrawal of consent (13%). 7 patients had normal study completion (44%). The study was closed early due to slow accrual owing to alternative treatment which became available at the time. The combination of gemcitabine, mitoxantrone, and rituximab in MCL was well-tolerated with manageable adverse events in spite of 93% neutropenia. Supplemented growth factor use was able to minimize neutropenia. No Grade 3–4 infection was reported. This regimen holds promise in patients with MCL and further studies are warranted. Updated data will be presented.