The Food and Drug Administration (FDA) has recently granted “fast track” status to OvaRex®, a monoclonal antibody designed to treat recurrent ovarian cancer.
Ovarian cancer is a common malignancy occurring in women in the United States, with about 25,000 new cases diagnosed each year. The ovary makes female hormones and stores all the eggs that are released once a month during ovulation. There are two ovaries, one on each side of the uterus. The earlier ovarian cancer is detected, the higher the cure rate. Unfortunately, because ovarian cancer begins deep in the pelvis and often does not cause any symptoms until advanced stages, the disease often goes unnoticed until it has reached a stage where it is incurable. Most women with ovarian cancer have advanced disease at the time of diagnosis. This means the cancer has spread from the ovary to other body locations within the abdomen, such as the surface or inside of the liver, intestine, or lymph nodes. Although many patients have an anti-cancer response to initial therapy, the majority of patients with advanced ovarian cancer ultimately experience a cancer recurrence.
OvaRex® is a monoclonal antibody targeted against the CA 125 antigen. Monoclonal antibodies can be produced in a laboratory and are able to identify specific proteins on the surface of certain cells and bind to them. This binding stimulates the immune system to attack and kill the cells to which the monoclonal antibody is bound. OvaRex® has been designed to identify and bind to CA 125, an antigen (protein) found on the surface of most ovarian cancer cells. A significant benefit of this approach is that OvaRex® only targets ovarian cancer cells, sparing healthy cells from destruction. This is in contrast to chemotherapy or radiation, which does not differentiate between cancer cells or healthy cells in the body, a characteristic leading to potentially destructive side effects.
Researchers from the Vancouver Cancer Center recently conducted a clinical trial evaluating OvaRex®. This trial involved 13 patients with advanced ovarian cancer who had failed multiple treatments. Over half of the patients in this study demonstrated a significant immune response to treatment. Following treatment with OvaRex®, one patient survived more than 18 months and 2 patients are still alive after almost 2 years. OvaRex® can be administered as an outpatient procedure with minimal side effects.
These results are significant as patients with advanced, recurrent ovarian cancer have a very poor prognosis with few treatment alternatives. Future clinical trials will evaluate OvaRex® in combination with other treatment modalities and/or when administered earlier in the course of the disease. Patients with ovarian cancer may wish to speak with their physician about participation in a clinical trial further evaluating OvaRex®. (Proceedings from the 32nd Annual Meeting of the Society of Gynecologic Oncologists, Nashville, TN, March, 2001)