Multimodal Dose Dense Therapy for Mantle Cell Lymphoma.

BACKGROUND: With the poor prognosis and outcome described in mantle cell lymphoma (MCL), there is a continuing need to explore treatment options that might overcome suspected underlying drug resistance and improve the current median survival of about 24 months. One strategy to overcome drug resistance has been the use of high dose therapy followed by autologous transplant. Newer agents such as the monoclonal antibodies (MoAb) rituximab and alemtuzumab which target CD20 and CD52 respectively have recently become available. We have therefore incorporated both a dose dense approach in combination with these antibodies to treat newly diagnosed and relapsed MCL patients.

PATIENTS AND METHODS: A total of 16 patients have been enrolled since February 2003. Induction therapy consisted of 1 cycle of cytarabine 3gm/m² IV Q12H for 8 doses, mitoxantrone 10mg/m² daily for 3 days, and Alemtuzumab 30mg IV 3 times a week for 6 weeks with growth factor support. All responding patients were mobilized with cyclophosphamide 4gm/m² and G-CSF 10 mcg/kg/day and/or bone marrow harvest. The transplant preparative regimen was carmustine 15mg/kg on day -6, etoposide 60mg/kg on day -4, and cyclophosphamide 100mg/kg on day -2 followed by autologous re-infusion. Consolidation was given with rituximab 375mg/m2 weekly for 4 doses at 6 weeks and 6 months post transplant.

RESULT: Of the 16 patients, 12 had stage IV, 1 stage III, 3 stage IIA, and 1 stage I disease. The median age was 60 (48 66 years). Eight were newly diagnosed and 8 had relapsed disease with at least 2 prior chemotherapy treatments. In the induction phase, overall response rate was 94% (15/16 patients) with 73% complete response (CR) and 27% partial response (PR). Response rate were 100% and 88% in the newly diagnosed and relapsed patients respectively but CR was similar (75%) in both groups. Nine patients have been transplanted and one patient is awaiting transplant. Six patients were not transplanted due to death in 2 patients with relapsed disease at study entry, and one each due to progression of disease, prolonged cytopenias of > 60days, mental status changes and inability to collect peripheral or bone marrow stem cell respectively. Among the transplanted patient, 78% (7/9) remain in CR with 2-year lymphoma progression free survival of 67% after a median follow-up of 487 days (range 175–787 days). Induction therapy toxicities included average neutropenia duration of 11.6 days and CMV reactivation of 50% that was equally distributed in the transplanted and non-transplanted patients. Peripheral stem cell collection was inadequate in 5 of the transplanted patients requiring bone marrow harvest.

CONCLUSION: Our preliminary data continue to show a high induction response rate with majority of patients who are able to proceed to the transplant phase remaining free of lymphoma at 24 months. Toxicity was manageable although bone marrow harvest was needed to obtain adequate stem cells in majority of transplanted patients. While CMV reactivation was observed in half of the patients, its effect on the ability of subjects to complete the study and on survival appear to be minimal. Although a small study, multimodal dose dense strategy with maintenance MoAb for patients with mantle cell lymphoma is a promising strategy that needs to be confirmed in larger number of patients with prolonged follow-up.