RIT Simplified
Radioimmunotherapy is often misunderstood and since several people are new to the blog, I'd like to simplify how it works.
RIT uses antibodies to attack malignant cells. Our bodies naturally produce antibodies which recognize and seek foreign substances that invade the body and they then call other components of the immune system into action. The concept of RIT dates back to 1908 when a German scientist, Paul Ehrlich, won a Nobel Prize for his studies of the immune system. Ehrlich believed that substances could be attached to antibodies to kill malignant cells. However, his theory required that scientists produce antibodies in the lab, and it wasn't until 1975 that two scientists produced man-made antibodies in a lab in Cambridge, England. When we hear the term "monoclonal antibodies," it means nothing more than antibodies that are man-made.
Scientists soon began to produce different monoclonal antibodies for different uses, but early trials fell short of expectations and interest in the monoclonals dwindled to a few small biotech companies and academics. One of those companies was Idec, which is now Biogen Idec. The company made history in 1997 when the FDA approved the first monoclonal antibody for the treatment of cancer, specifically for low-grade lymphoma. The drug, known as Rituxan, identifies, then attaches to lymphoma cells. Ideally, this action triggers the body's own immune system into attacking the diseased cells and causing them to self-destruct.
Several years earlier, in the late 1980's, two University of Michigan scientists, Drs. Mark Kaminski and Richard Wahl, believed that monoclonal antibodies would be more successful if, instead of relying on the body's own immune system, they could also carry radiation directly to the tumor cells. They began working with an antibody called B1, which recognizes and attaches to a specific protein, called CD20, which is located on the surface of B cells, from which virtually all lymphomas are derived. To that antibody, they attached minute quantities of a radioactive isotope known as I-131, which is a molecule that emits radiation. Effectively, this created a guided missile. The antibody seeks the target on the surface of the cells, latches on, and calls the body's own immune system into action. For an extra lethal effect, the I-131 emits a burst of radiation directly to the tumor. This dual-action drug became known as Bexxar.
In 1993, Idec began investigating its version of this treatment. To Rituxan, which was then still in the early stage of development, they added a different radioactive isotope called Yttrium-90. This combination became known as Zevalin.
Combining a monoclonal antibody with a radioactive isotope creates a radiolabeled antibody, and using radiolabeled antibodies for treatment is known as radioimmunotherapy. Unlike chemotherapy, which uses chemicals, requires months of treatment and often causes unpleasant, even life-threatening, side effects, RIT is given in two doses a week apart, and because it spares healthy cells, side effects are minimal. Better still, years of clinical trials show that RIT produces better results than either chemotherapy or Rituxan.
In my own case, two kinds of chemotherapy, one of which was combined with Rituxan, had to be suspended during treatment because it wasn't destroying the malignant cells. However, those treatments did deprive me of my hair and send me to the hospital with numerous side effects and complications. RIT became available in the nick of time and ultimately saved my life. I just had a checkup on Monday and remain free of lymphoma and full of energy. Today, that means that I have been disease free for 4 years, 4 months, and 14 days. As I told my doctor, I'm not counting the time, only my blessings.
Betsy