CRAIG M. KESSLER, MD: I think the basic principle over here for the use of Rituximab is that it is an antibody which is directed against other types of antigens or proteins on the surface of lymphocytes, a type of white cell in the circulation. These particular white cells are the white cells that are responsible for producing certain types of blood cell malignancies called lymphomas and chronic lymphocytic leukemias. The characteristic protein on their surface with the target of the antibody directed against that surface, will allow that cell to be bound by the antibody and then the antibody will destroy that malignant cell.
BRETT SCOTT: At this meeting there are several presentations on the use of Rituxan for ITP or TTP. Can you comment on the rationale behind this and the success?
CRAIG M. KESSLER, MD: ITP is immune thrombocytopenic purpura. TTP is thrombotic cytopenic purpura. These are diseases of the immune system which both result in a very dramatic decrease in the platelet count in the bloodstream. And when these platelet counts decrease then the patient is at increased risk for bleeding into organs, brain, GI tract, bladder, etc., and it can cause very severe disease. Knowing that the immune system is altered in these individuals and that it's the proliferation of these abnormal lymphocytes that are associated with the development of the disease, then the use of Rituximab again can be used to target those specific abnormal lymphocytes in the bloodstream and in the bone marrow and thereby eradicate this population of cells responsible for producing the disease.
BRETT SCOTT: There are also presentations this weekend on the use of Rituxan for certain forms of anemia and Factor 8 deficiency. Is the rationale for use in these conditions the same as ITP or TTP?
