Radioimmunotherapy with 131I-rituximab for patients with relapsed/refractory B-cell non-Hodgkin's lymphoma (NHL)

Aim: To evaluate the efficacy and safety of radioimmunotherapy (RIT) with radioiodinated human/murine chimeric anti-CD20 monoclonal antibody rituximab (I-131-rituximab) for treating Korean patients with relapsed or refractory B-cell non-Hodgkin's lymphomas (NHL). Methods: All patients received unlabeled rituximab 70 mg immediately prior to the administration of a therapeutic dose (median dose: 7.3 GBq) of I-131-rituximab. The tumor response was evaluated 1 month later by contrast enhanced F-18-fludeoxyglucose positron emission tomography-computed tomography. Results: Between May 2004 and October 2006, 24 patients received single treatment with I-131-rituximab. The overall response rate (ORR) was 29%; 46% (three complete responses, two partial responses (PR) for patients with low grade B-cell NHL (LGL) and 9% (one PR) for patients with diffuse large B-cell lymphoma (DLBCL). After a median follow-up of 55 months, the median progression-free survival (PFS) for all the patients was 2.2 months. The median overall survival (OS) was 11.3 months. There were statistically significant differences between the LGL and the DLBCL for the median PFS (4.5 months vs 1.3 months, respectively, P = 0.0007) and the median OS (30.3 months vs 6.5 months, respectively, P = 0.0295). Grades 3-4 thrombocytopenia and neutropenia occurred in 33% (8/24) and 21% (5/24) of the patients, respectively. Conclusion: RIT with I-131-rituximab seems to be effective and tolerable for patients with refractory LGL, although this treatment had modest activity in patients with refractory DLBCL. Further studies are warranted to determine the efficacy of I-131-rituximab for treating the patients with DLBCL.