Robert C. Bast Jr., M.D.

Early Detection Biomarker for Ovarian Cancer

Research Area: Early Detection

Portrait of Robert C. Bast Jr., M.D.
Robert C. Bast Jr., M.D.
Early Detection Biomarker for Ovarian Cancer

Robert C. Bast, Jr. M.D., was searching for an immunological treatment for ovarian cancer in 1981, when instead he found a circulating biomarker that helps to detect the disease. The marker became known as CA-125, a part of marketed tests to help predict ovarian cancer in women at risk of the disease.

As a research associate in NCI’s Biology Branch in the early 1970s, Dr. Bast worked with immunotherapy pioneer Berton Zbar, M.D., to optimize immunotherapy treatments with injections directly into the tumor using the body’s normal immune response. Later, in his own laboratory at the Dana Farber Cancer Institute, he wanted to use the techniques he learned at NCI to develop an immunotherapy for ovarian cancer. He joined forces with Robert Knapp, M.D., a gynecologic oncologist, and after some success, decided that finding an antibody specific to human ovarian cancer would be the best way to elicit the wanted immune response to the tumor.

Using new technology for the time, they worked to create laboratory-produced antibodies to mimic the immune system’s attack process by recognizing antigens, typically proteins, produced by ovarian cancer cells. The cancer antigen recognized by this antibody (which was the 125th clone) became known as CA-125. They found, however, that ovarian cancer shed CA-125 into the fluid surrounding the tumor, making it a poor target for therapy. Instead, the shed antigen was later used to monitor the effectiveness of ovarian cancer treatment, and since then, CA-125 has evolved to become part of the widely used Overa and ROMA tests to predict ovarian cancer risk in women with an abdominal mass.

To learn more about Dr. Bast, read his reflection on the discovery of CA-125.