Phase II Study of Rituximab Combined with Cladribine and Mitoxantrone in Relapsed or Refractory Indolent Non-Hodgkin’s Lymphoma

BACKGROUND. Synergistic or additive activities for rituximab and cladribine have been shown in preclinical studies. Indolent Non-Hodgkin’s lymphoma (I-NHL) tends to recur with shortening intervals of remission after standard chemotherapy. New modalities of treatment are necessary. Therefore, we evaluated the feasibility, efficacy, and toxicity of combined regimen that consisted of rituximab plus cladribine plus mitoxantrone (the RCM regimen) in the treatment of patients with relapsed or refractory I-NHL.

METHODS. The RCM protocol consisted of rituximab at a dose of 375 mg/m² on Day 1, cladribine at a dose of 0.09 mg/kg per day on Days 2 through 6, and intravenous mitoxantrone at a dose of 6 mg or 10 mg/m² per day on Day 2. The RCM courses were repeated at 4-week intervals, for up to 4 cycles.

RESULTS. Fourteen patients with I-NHL and one patient with mantle cell lymphoma entered in the study. The median age was 60 (range 47–77) and 8 were females. Histology was small lymphocytic lymphoma (n=1), follicular lymphoma (n=13), mantle cell lymphoma (n=1). Median time from diagnosis to RCM treatment was 3.6 (range 0.2–8.1) years and median number of prior treatment regimen was 2 (range 1–4). Twelve patients (80%) had recurrent disease after prior therapy including high dose therapy with autologous stem cell transplant, and 3 patients (20%) had refractory disease. Thirteen patients were treated on the RCM regimen, and 8 patients (61.5%) achieved a complete response, 3 patients (23.1%) achieved a partial response. Therefore, the overall response rate was 92.3%. Median time to response was 2.8 months (range 1.0–6.7). Median progression free survival of responders was 16.5 (range 1.3–25.5) months. The treatment revealed tolerability, with episodes of severe neutropenia (grade 3 and 4) observed in 12 patients (85.7%), episodes of grade 3 and 4 thrombocytopenia observed in 2 patients (15.4%). However, severe infections were not observed in any patients.

CONCLUSIONS. The RCM regimen is highly effective and well tolerated modalities of treatment in heavily pretreated and relapsed or refractory patients with I-NHL.