The immune system generally does not recognize cancer cells in the body as enemies. The insertion of the antigen-specific T cell receptors engineered to seek out a tumor antigen on the surface of the melanoma cells in effect uncloaks the malignant cells, revealing them as deadly invaders that must be sought out and killed.
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 then result in better monitoring response to therapy in melanoma patients.
In this study, the cells were injected into the bloodstreams of the mice and they had found and begun to fight the melanoma within two to three days. The mice were imaged periodically for 10 days to ensure the lymphocytes were indeed killing the cancer. The process to find and kill the malignant cells could take longer in people, Ribas said.
If a patient's tumor did not respond well to the administration of the genetically engineered T cells, scientists could determine by PET scanning whether the cells had not successfully made it to the tumor site or, if they did arrive, whether or not they functioned as expected. Monitoring the immune response also could provide clues on ways to better engineer the lymphocytes to more effectively enter and attack the tumors.
In this study, about one million genetically engineered lymphocytes were created and injected into a mouse. In humans, the number of tumor-seeking cells needed to fight the cancer is about one billion, Ribas said.
Ribas and his team are working now on creating a vector, or vehicle, to insert the T cell receptors and report
'/>"/>
| Contact: Kim Irwin kirwin@mednet.ucla.edu 310-206-2805 University of California - Los Angeles Source:Eurekalert |