Dr. Vafa Shahabi, Advaxis' Director of Research and Development, reports that because the human immune system is not designed to fight cancer on its own, she and her colleagues are trying to harness its power through a new kind of life form: specifically a family of vaccines, which they call Lovaxin. The vaccines are comprised of new strains of bacteria created in Advaxis' laboratory that are programmed to kill off specific cancers.
The Key: A Microbe Found in Dairy Products
Central to this startling discovery is the microbe Listeria monocytogenes, a common bacterium found in milk, cheese and other dairy products. This microorganism apparently aids in fighting cancer by activating the body's own killer (cytotoxic T) cells to elicit a stronger than normal immune response to the presence of cancer cells. The vaccines "teach" the immune system to mount a specialized, targeted response that is lethal to cancer.
When Listeria is introduced in the body, it has a powerful, direct stimulatory effect on the activities of tumor-killing T cells. "Essentially the modified Listeria vaccines harness the power of the immune system against this infectious agent," explains Dr. Shabahi, "and then directs it to successfully attack cancer cells. The bacterium in effect then becomes a cancer-fighting 'Trojan horse,' with the enemy tucked inside."
For breast cancer, Dr. Shababi's team fused Listeria with a tumor-associated protein, HER-2/Neu, to immune cells, to create a vaccine called Lovaxin B. What these cells do is enlist killer T cells to seek and destroy tumor cells that over-express the HER-2/Neu molecule. This is significant because HER-2/Neu is over- expressed in 20%- 40% of all breast cancers.
As Dr. Shababi explains: "We not only created a new breast cancer vaccine, but also have a new life form, since the modified Listeria becomes a new strain, not seen in nature. In effect, it becomes a cancer fighting "superbug" capable of treating breast cancer in patients whose tumors express the HER-X/Neu protein." Advaxis has already created several strains for potential use in future vaccines to treat other cancers. The company is also currently testing its cervical cancer vaccine, Lovaxin C, in phase I/II trials.