"MIRO" Molecularly Oriented Immuno-radio-therapy

Stage I/IIA follicular lymphoma (FL) is considered a localized disease that can be adequately treated with radiotherapy alone. This strategy is recommended by the guidelines of the "Società Italiana di Ematologia" (SIE) and of the "European Society for Medical Oncology" (ESMO) The accurate definition of the truly localised forms represents a crucial issue in order to ensure an appropriate treatment design for such patients. The characteristic t(14;18) translocation, which leads to the over-expression of the Bcl-2 gene, is found in approximately 85% of FL; cells bearing this translocation can be detected in the peripheral blood (PB) or bone marrow (BM) by polymerase chain reaction (PCR). PCR for the t(14;18) translocation provides a sensitive device to identify the presence of minimal non-Hodgkin lymphoma (NHL) cell contamination. Previous experiences have demonstrated that despite the limited stage, Bcl-2/IgH+ cells can be found at diagnosis in PB and/or BM of the majority of the patients. After treatment with local radiotherapy confined to the involved lymph node(s) only, disappearance of circulating Bcl-2/IgH+ cells in PB and/or BM was demonstrated in approximately 60% of positive patients. Quantitative PCR demonstrated the feasibility of clearing PB and BM Bcl-2+ cells after local irradiation of the primary site of the disease only when the basal number of lymphoma cells was \<1:100 000. Anti-CD20 monoclonal antibody treatment has clearly demonstrated, both alone and in combination with chemotherapy and radiotherapy, a high therapeutic potential in FL. A significant impact of treatment with the anti CD20 monoclonal antibody in reducing the minimal residual disease in FL has been demonstrated in several studies when used as consolidation or during the maintenance phase. No data are currently available concerning the ability of anti-CD20 antibody treatment in reducing the proportion of Bcl-2 positive residual cells after radiotherapy in localized FL. The objective of this study is to take advantage of the therapeutic potential of anti-CD20 monoclonal antibody to reduce or eliminate minimal residual disease in patients with FL in localized stage (I/II) after conventional treatment with local radiotherapy of the involved site(s). The effectiveness of anti-CD20 monoclonal antibody treatment will be determined by the proportion of negativization of residual Bcl-2 positive cells after radiotherapy, evaluated by qualitative and quantitative PCR detection of viable Bcl-2/IgH rearranged cells in PB and/or BM.