OvaRex® Promising for Recurrent Ovarian Cancer
According to proceedings from the annual meeting of the Society of Gynecologic Oncologists (SGO), the combination of OvaRex® plus chemotherapy may significantly improve survival in patients with 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, thus sparing healthy cells from destruction. This is in contrast to chemotherapy or radiation, which do not differentiate between cancer cells or healthy cells in the body, a characteristic leading to potentially destructive side effects.
Researchers from the U.S. Oncology in Dallas recently conducted a clinical trial evaluating OvaRex® plus chemotherapy in 15 patients with recurrent ovarian cancer. After four doses of therapy, 33% of patients achieved anti-cancer responses or disease stabilization. After five doses of therapy, almost 40% of patients experienced a complete remission (disappearance of cancer). Patients who demonstrated an immune response to OvaRex®, consisting of elevated levels of immune cells, achieved a significantly greater anti-cancer response rate and survival time than patients who did not demonstrate an immune response. The average time to disease progression following therapy has not yet been reached in patients who demonstrated an immune response compared to 10.6 weeks for patients who did not respond. The average survival time following therapy has not yet been reached in patients who demonstrated an immune response, compared to 27.6 weeks for non-responders.
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 annual meeting of the Society of Gynecologic Oncologists, Miami, Florida, March 16-20, 2002)
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