RESEARCHERS AT UCLA'S JONSSON COMPREHENSIVE CANCER CENTER created a large, well-armed battalion of tumor-seeking immune-system cells and used positron emission tomography (PET) to watch in real time as they traveled throughout the body to locate and attack dangerous melanomas.
The gene-therapy work, done with melanomas grown in mice, employed a crippled HIV-like virus as a vehicle to arm the lymphocytes with T-cell receptors, which caused the lymphocytes to become specific killers of cancerous cells. A reporter gene, which glows “hot” during PET scanning, also was inserted into the cells. It allowed researchers to track the lymphocytes as they made their way to the lungs and lymph nodes and then specifically homed in on the tumors wherever they were located in the body.
“We’re trying to genetically engineer the immune system to become a cancer killer and then image how the immune system operates at the same time,” says Antoni Ribas, M.D., associate professor of hematology-oncology and author of the study in the July 2010 online edition of Proceedings of the National Academy of Sciences.
By imaging the genetically engineered T cells as they seek out and attack the cancer, the scientists can closely examine the processes of the immune system as it fights malignancies, which could result in better monitoring responses to therapy in melanoma patients. Dr. Ribas and his team are working now on creating a vector, or vehicle, to insert the T-cell receptors and reporter gene into the lymphocytes in a way that is safe to use in humans.