Monoclonal antibodies show promise in treatment of blood cancer

Immunologists at Duke University Medical Center have found that a new monoclonal antibody that targets immune system B cells could be a pioneering treatment for leukemias, autoimmune diseases and transplant rejection.

B cells are the main producers of antibodies, the body's defense mechanism against invading antigens. But the uncontrolled production of these B cells is responsible for leukemias such as multiple myeloma and acute lymphoblastic leukemia and autoimmune diseases like rheumatoid arthritis and lupus. The findings of the study have been published in the online Early Edition of the Proceedings of the National Academy of Sciences for the week October 10, 2005.

Professor and Chair of Immunology Thomas Tedder, Ph.D., Norhito Yazawa, Yasuhito Hamaguchi and Jonathan Poe in Tedder's laboratory are the co-authors of this report. Basically, monoclonal antibodies are directed against specific proteins. In this study, the Duke researchers targeted a surface protein called CD19, which is found on the B cells. When this was administered to laboratory mice, the researchers found that this reduced the number of B cells greatly. Significantly they also found that this monoclonal antibody behaved aggressively against B cell tumors. In 10 mice with malignant B cell lymphomas, the monoclonal antibody prevented the appearance of tissue tumor circulating cells for seven weeks. In contrast untreated mice died in three weeks. "We were actually quite shocked at how effectively CD19 mAb-treatments prevented malignant B cell expansion," said Tedder. "Treatment of such tumors in mouse models is extraordinarily difficult." Based on their findings, the researchers conclude, "In addition, this treatment could greatly aid transplant patients who require multiple organ transplants because they develop a humoral antibody response to their transplanted organs, or they already have preformed antibodies that prevent them from accepting some donor grafts."