Dr. Andrew Raubitschek’s work in this ground-breaking area of medicine has resulted in new treatments - and new hope - for cancer patients. Radioimmunotherapy attaches radioactive isotopes to genetically engineered monoclonal antibodies (mAbs), which carry the radiation directly to tumor cells. A major advancement has been the identification of the carcinoembryonic antigen (CEA) in more than 60% of colorectal, breast, and lung cancers. We have developed technology that utilizes anti-CEA antibodies for imaging and therapy.
Among the patients benefiting from this technology are those receiving bone marrow transplants (BMT), who currently receive total body irradiation (TBI) in combination with high-dose chemotherapy as part of their treatment. Though intended for the patient’s cancer, TBI affects the entire body and causes harsh side effects. Radioimmunotherapy offers a more targeted treatment by focusing radiation on the cancer while only minimally affecting surrounding tissues. These efforts have led to the development of a variety of molecularly engineered antibodies, culminating in clinical trials.
Our radioimmunotherapy program is investigating a new area of medicine that combines radiation and immune therapy using monoclonal antibodies to:
- Locate cancer within the body, known as radioimmunoimaging (RII) and
- Treat cancer, called radioimmunotherapy (RIT).
RII uses a radioactive material attached to specially designed antibodies to locate cancer within the body. Antibodies are naturally produced by the body's immune system. They are normally used to fight infections caused by bacteria and viruses. The antibodies used in RII are monoclonal antibodies (MAbs). These antibodies are developed in the laboratory and recognize substances on the surface of tumor cells. These antibodies are further "engineered" in the laboratory to improve their efficacy. The MAbs are then modified to bind radioactive metals (Indium-111 or Copper-64) or radioactive iodine (Iodine 123, Iodine 131, or Iodine 124) which can be visualized with a special camera in Nuclear Medicine. Images from these cameras show areas where the MAbs have localized in the body.
RIT uses the same MAbs for therapy but switches the radioactive metal to Yttrium-90, which delivers higher levels of local radiation to the tumor. The radiolabeled MAb is administered through a vein and then circulates through the body to the surface of tumor cells. The tumor cells are destroyed by the radiation given off from the localized radiolabeled MAbs.
Three different antibodies are being used in our current clinical trials. One binds carcinoembryonic antigen (CEA), a tumor antigen found in certain patients with breast, colon, lung, thyroid and ovarian cancers. The second antibody binds to CD20, an antigen found on the surface of certain lymphomas. The third antibody binds to HER2 (human epidermal growth factor receptor 2) which is overexpressed in approximately 25% of breast cancer patients.