Cd20 Expression and Effects on Outcome of Relapsed/Refractory Diffuse Large B Cell Lymphoma after Treatment with Rituximab

Abstract

Introduction: Down regulation of CD20 expression has been reported in diffuse large B cell lymphoma (DLBCL)).<br />Therefore, it is important to determine whether chemotherapy with rituximab induces CD20 down regulation and effects<br />survival. Objectives: To determine the incidence of down regulation of CD20 expression in relapsed DLBCL after<br />treatment with rituximab and to compare outcomes and assess pattern of relapse between CD20 negative and CD20<br />positive cases. Methodology: We retrospectively reviewed patients with relapsed DLBCL who received rituximab in<br />the first line setting at Aga Khan University Hospital between January 2007 and December 2014. Data were recorded<br />on predesigned questionnaires, with variables including demographics, details regarding date of diagnosis and relapse,<br />histology, staging, international prognostic index, treatment and outcomes at initial diagnosis and at relapse. The Chi<br />square test was applied to determine statistical significance between categorical variables. Survival curves were generated<br />by the Kaplan–Meier method. Results: A total of 54 patients with relapsed DLBCL were included in our study, 38 (70<br />%) males and 16(30%) females. Some 23 (43%) patients were at stage IV at the time of diagnosis and 34 (63%) had B<br />symptoms. The most frequent R-IPI at diagnosis was II in 24 (44%) patients. Only 6 (11%) did not show CD20 expression<br />on re-biopsy for relapsed/refractory disease, 2 with CD20 negative DLBCL responding to second line chemotherapy.<br />A complete response after salvage chemotherapy was noted in 16 (29.6%) cases with relapsed/refractory DLBCL.<br />Seven (13%) patients underwent an autologous bone marrow transplant as consolidation after second line treatment.<br />Median overall survival was 18 months in CD20 positive vs. 13 months in CD20 negative patients. Conclusion: This<br />study demonstrated that a small percentage of patients treated with rituximab lose their CD20 expression at the time<br />of relapse. However, it is unclear whether this is associated with an inferior outcome.