Rituximab is a monoclonal antibody specific for the cell surface CD20 protein and is used to treat non-Hodgkin's lymphoma (NHL) characterized by overgrowth of B-cells. More than 90% of B-cell cancers express the CD20 protein on the cell surface, a requirement for the proper function of rituximab. By binding the CD20 protein on the B-cell, the antibody targets it for removal from the circulation. Its developers believe that rituximab triggers both cell-mediated and complement-mediated means to kill the B-cells.

In the current study investigators at the University of Texas Southwestern Medical Center (Dallas, USA) evaluated results of a randomized, double-blind study in which 87 patients between 8 and 40 years of age who had newly diagnosed type I diabetes were assigned to receive infusions of rituximab or placebo on days 1, 8, 15, and 22 of the study. The primary outcome, assessed one year after the first infusion, was the geometric mean area under the curve (AUC) for the serum C-peptide level during the first two hours of a mixed-meal tolerance test. Secondary outcomes included safety and changes in the glycated hemoglobin level and insulin dose.

Results published in the November 26, 2009, issue of the journal New England Journal of Medicine (NEJM) revealed that after one year, the mean AUC for the level of C-peptide was significantly higher in the rituximab group than in the placebo group. The rituximab group also had significantly lower levels of glycated hemoglobin and required less insulin. More patients in the rituximab group than in the placebo group had adverse events after the first infusion. The reactions appeared to be minimal with subsequent infusions. There was no increase in infections or neutropenia with rituximab.

The finding that B-lymphocytes contribute to the pathogenesis of type I diabetes may open a new pathway for exploration in the treatment of patients with this condition.

"Our findings in no way suggest that rituximab should be used as a treatment or that it will eliminate the need for daily insulin injections,” said senior author Dr. Philip Raskin, professor of internal medicine at the University of Texas Southwestern Medical Center. "This is not a cure for type I diabetes. The results do, however, provide evidence that B- cells play a significant role in type I diabetes and that selective suppression of these B-cells may deter the destruction of the body's beta cells.”

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University of Texas Southwestern Medical Center