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