RadioimmunotherapyMark Kaminski, M.D., Director, Adult Hematology Clinic pioneered the development of a treatment called radioimmunotherapy. This type of treatment involves the use of radioactive antibodies that seek out tumor cells. Dr. Kaminski's work involved the development of Bexxar as a radioimmunotherapeutic agent.
Bexxar regimenBexxar (the commercial name for the compound tositumomab and iodine I131 tositumomab) is a monoclonal or man-made antibody, which is a protein that attaches to and rids the body of a foreign substance (called an antigen). In more than 95% of low-grade or follicular non-Hodgkin's lymphoma cases, a specific cancerous antigen called CD-20 is expressed on the surface of the patient's B-cells (a type of white blood cell). When Bexxar is injected into the blood, it goes directly to these cells and attaches to them. The immune system is activated, as when the body reacts to an infection, and Bexxar tries to "gobble up" the cancer. But Bexxar carries an additional payload in the form of iodine 131, which gives off radiation, one of the most effective treatments for lymphoma. So Bexxar acts like a guided missile, delivering radiation to cancer cells while avoiding most normal tissues.
Treatment with Bexxar is a dramatic contrast to chemotherapy. Patients on chemotherapy face a repeating cycle of treatment and side effects followed by recovery, with the entire process extending over several months. Bexxar patients receive one test injection at the beginning of a week, and a therapeutic dose later in the week to conclude their treatment. According to Kaminski, "We have a patient celebrating her 10th year of remission thanks to Bexxar. Previously, after seven courses of chemotherapy, she had never known more than six months of remission. With Bexxar, your life is not spent in treatment. You're back to living."
With a single treatment of Bexxar (an iodine-131-tagged anti-CD20 antibody), dramatic tumor regressions, including complete remissions, have been observed in 70 percent of patients who had undergone prior chemotherapy for low-grade, follicular non-Hodgkin's lymphoma and had either relapsed or were no longer responding to chemotherapy. In the 35 percent of patients who achieved complete remissions, no return of lymphoma has been seen up to eight years after receiving treatment. In a study conducted in patients with low-grade lymphoma who had never received any other prior treatment, 95 percent of patients have had tumor remissions and 75 percent had complete remissions. Complete remissions are ongoing from two to five years so far. In contrast to standard chemotherapy, which can cause serious side effects, these patients have had few side effects.
The Food and Drug Administration approved Bexxar for treatment of patients with relapsed or refractory follicular lymphoma in June 2003.