Unique approach to enhance the immune system in patients with breast or colorectal cancer

Researchers at Mount Sinai School of Medicine are conducting clinical trials on a unique approach to enhance the immune system in patients with breast or colorectal cancer.

The study uses a potent immune-enhancing gene delivered directly into the cancer cells to make them look foreign to the body's immune system, which will then attack and destroy the cancer.

In experiments with laboratory animals, Mount Sinai researchers have demonstrated that their approach, known as tumor immunization, extended life in all animals tested and wiped out cancer entirely in up to 20-30% of animals whose breast or colorectal cancer had spread. With currently available treatments, the prognosis for patients with breast or colorectal cancer which has spread to other organs, including the liver, is poor.

"Cancer cells are able to grow unimpeded by the body's defenses because they look very similar to healthy cells, with only very subtle differences that pass under the radar screen of the body's immune cells," said Savio Woo, PhD, Professor and Chairman of the Department of Gene and Cell Medicine at Mount Sinai School of Medicine. "We use gene transfer technology to insert an immune enhancing gene into the cancer cells that makes them visible to the body's natural immune defenses."

The method of tumor immunization which Mount Sinai researchers developed involves transferring a gene that codes for Interleukin-12 (IL12) into cancer cells directly in the patient's tumor. IL12 is a potent immune enhancing protein that is not normally produced by cancer cells. When the cancer cells produce this protein as a result of gene transfer it acts as a signal to a special class of white blood cells of the immune system telling them, "These cancer cells are dangerous. Come over here and destroy them."

The laboratory animal studies conducted by Dr. Woo and colleagues have provided evidence that delivering the IL12 gene to cancer cells can trigger a targeted immune response that destroys tumor cells. Their impressive results along with extensive pharmacological and toxicology studies they conducted were sufficient evidence to convince the FDA, NIH and Mount Sinai's Institutional Review Board that the promise of this research is ready to be tested in humans. The first phase of clinical trials to establish the safety of these treatments in patients with breast or colorectal cancer began recently.

Dr. Woo and colleagues developed a disarmed virus that carries the IL12 gene into the cancer cells. "The virus was developed in a special multi-million dollar facility here at Mount Sinai," said Dr. Woo. "This state-of-the-art facility provides us the means to produce a disarmed virus that can not reproduce itself and can not lead to a sustained infection in patients. In animal experiments we have found that this maximizes both effectiveness and safety, and we hope to see the same in humans."

The researchers will use one of the tumors which has spread to the liver as the target for inserting the gene. "The procedure does not require surgery and is done with just local anesthesia to the skin," said Max W. Sung, MD, Medical Director for the Derald H. Ruttenberg Cancer Treatment Center and Associate Professor in Hematology-Oncology at Mount Sinai School of Medicine. "Using one to three needles, the disarmed virus harboring the IL12 gene is injected through the skin into a metastatic tumor in the liver. We perform an ultrasound exam at the same time to track the needles so that we can deliver the virus to the correct location. The entire procedure can be completed within half an hour."