Rituximab followed by localized radiation therapy in limited stage indolent non-Hodgkin’s lymphoma: Preliminary results of a pilot study

Abstract

6696 Background: The most common approach for limited-stage low-grade non-Hodgkin’s lymphoma (NHL) is localized radiotherapy (L-RT). However, some studies have reported prolonged disease-free survival if chemotherapy (CT) is combined with RT. Nevertheless, there is some concern about the use of cytotoxic drugs in this group of patients. In order to deliver a systemic anti-lymphoma drug while avoiding the potential toxicity of chemotherapy, a phase I study program was designed combining the anti-CD20 Rituximab (Rb) monoclonal antibody with L-RT. Aim of the study was to assess toxicity profile, overall response rate and time to treatment failure. Methods: Since January 2000, patients with stage I-II Follicle Center Lymphoma (FCL) or low-grade MALT lymphoma, have been enrolled in a study program, including 4 Rb doses (375 mg/sqm) given at 1 week intervals, followed by L-RT, limited to involved sites with standard doses of 36–40 Gy. So far, 18 patients have been treated and are evaluable: 11 nodal FCL (9 inguinal, 1 cervical, 1 parothid gland involvement), 5 low-grade MALT lymphoma (1 parothid gland, 2 orbital and 2 breast involvement) and 2 primary cutaneous FCL. Results: Treatment was well tolerated. In 4 patients mild Rb-related side effects were observed (fever with chills); no hematological toxicity was seen. Mild RT-induced xerostomia (grade 1) was recorded at 2 years from RT in the patient treated for parothid gland MALT NHL. All patients were in CR at the end of the combined treatment. With a median follow-up of 20 months, all 18 patients are presently alive and well, 17 of them in continuous CR. One patient (inguinal FCL) relapsed out of radiation field, but with different histology (diffuse large B cell). Conclusions: Administration of 4 doses of Rb followed by L-RT appears to be a safe, tolerable and active combined modality regimen for patients with grade 1–2 FCL or low-grade MALT NHL presenting with limited stage disease. Among them, the use of Rb along with RT might result in prolonged event-free survival reducing outside-field relapse rate without the need of CT administration. Furthermore, the addition of Rb might allow to reduce RT doses and treatment volumes, minimizing RT toxicity. No significant financial relationships to disclose.