Israeli Researchers Make Progress in Fighting Cancer

Researchers at Israel’s Weizmann Institute have discovered the key to combating one of the most devastating kinds of cancer.

, | updated: 18:43

Prostate cancer, one of the leading causes of cancer death among men worldwide, spreads through the body to bones, where it is very difficult to treat. The resulting metastasis to the bone causes over 70% of prostate cancer deaths.

Prof. Zelig Esh-Har, Head of the Immunology Department at Weizmann Institute, has now shown how a treatment that effectively combats cancer in the prostate can be redirected to the bones. A Weismann Institute release explains.

The treatment is based on cells engineered to combine two different types of anti-invader weapons used by the immune system: T-cells and antibodies. The latter are best at recognizing foreign or altered molecules such as antigens on the outer walls of bacteria, viruses or cancer cells. T-cells are better at killing unwanted cells, but are not as adept at identification, especially of tricky cancer cells that may already have developed methods of evading detection by the immune system.

By attaching an antibody-based structure designed to recognize specific cancer cells directly to a T-cell receptor, Esh-Har produced custom-modified cells, dubbed T-bodies, which are effective in both finding and killing cancer cells.

Getting T-bodies into the bone to treat metastasized cancer was more difficult, though. Cancer in such cases is likely to be spread throughout the bone, to hard-to -reach places. When Esh-Har’s research team first injected T-bodies into immuno-deficient mice in whose leg bones human prostate cancer had developed, they saw no real improvement. This indicated to them that the cells were not getting to the cancer in significant enough quantities to have an effect.

The Weizmann team addressed the problem by “preconditioning” the mice, using one of two strategies already in use in some forms of cancer therapy: low doses of radiation or a specific chemotherapy drug. Both treatments cause some disruption in the bone marrow, the intended target of the T-bodies. In response, the bone marrow sends out a chemical distress signal to the immune system. This signal not only alerts immune cells such as T-cells to the danger, but assists them in homing in on the problem area and in passing through barriers that might otherwise prevent them from getting into the bone marrow tissue.

Mice treated with either therapy 24 hours prior to being injected with T-bodies showed a significant drop in the tumor marker, PSA (an indicator of cancer levels), a reduction in the tumor load and prolonged survival. Because the method holds promise for treating disseminated cancers that are resistant to other forms of therapy, Esh-Har hopes to move it into clinical trials in the near future.