Multifaceted Attack on Ovarian and Breast Cancer

Ovarian and breast cancer, which strike hundreds of thousands of women throughout the world each year, are under intense study at the Weizmann Institute.

Prof. Ruth Arnon and Dr. Bilha Schechter of the Department of Chemical Immunology, together with Prof. Meir Wilchek of the Department of Membrane Research and Biophysics, have developed an experimental immunotherapy that would treat ovarian cancer more effectively while sparing women the devastating side effects of present treatments. The scientists are trying to decrease the toxicity of cisplatin, a common ovarian cancer drug, by supplying it as part of a much larger molecule. Using immunotargeting, a method in which antibodies guide drug molecules towards malignant cells, they prompt the drug to zero in on the tumor and circumvent healthy tissues.

The approach consists of a two-step treatment involving the avidin-biotin binding complex, a field in which Prof. Wilchek has been working for over two decades. A patient would first receive an injection of monoclonal antibodies modified with biotin that home in on an ovarian tumor, and then a dose of a cisplatin sugar-avidin complex. Because of the high chemical affinity of avidin for biotin, the cisplatin complex is picked up specifically where it is needed by the biotinylated antibodies present in the tumor tissue.

Another researcher in the Department of Chemical Immunology, Prof. Benjamin Geiger, is developing an improved diagnostic classification of the various types of ovarian cancer based on the use of monoclonal antibodies. While people tend to think of ovarian cancer as a single entity, the ovaries can in fact be affected by various malignancies that require different treatments. Prof. Geiger's system may eventually allow physicians to select optimal therapies for different kinds of ovarian cancer. The work is conducted in close collaboration with Prof. Bernard Chernobilsky of the Kaplan Medical Center.

A third ovarian cancer study is being carried out by Dr. Michal Neeman of the Department of Hormone Research, who is using magnetic resonance imaging, or MRI, to investigate factors that control the spread of ovarian tumors. The focus of her research, conducted in collaboration with Prof. Eli Keshet of the Hebrew University-Hadassah Medical School, is a growth factor that appears to call upon blood vessels to invade a tumor, a process that allows the cancer to grow explosively. This process is simulated by the use of multicellular spheroids about half a millimeter to a millimeter in size, which are composed of human ovarian cancer cells.

MRI may also help evaluate the effectiveness of hormone therapy for breast cancer, allowing doctors to identify women who may best benefit from such treatment. Taking advantage of her earlier work with laboratory animals, Prof. Hadassa Degani of the Department of Chemical Physics is now using MRI to monitor the response of breast tumors to therapeutic hormones in human patients.

The various MRI methods and magnetic resonance of carbon and phosphorous molecules make it possible to measure processes in breast tissues and characterize changes in the composition, perfusion, vitality and metabolic activity of the tumor cells.

This research is conducted in collaboration with Prof. Raphael Catane and Prof. John M. Gomori and their colleagues at the Hebrew University Hadassah Medical School.

Prof. Wilchek holds the Marc B. Gutwirth Chair of Molecular Biology; Prof. Arnon, the Paul Ehrlich Chair of Immunology; and Prof. Geiger, the Erwin Neter Chair of Tumor Biology.