United States pharmaceutical company Kite Pharma has released results from the initial half-year trial of its new chimeric antigen receptor (CAR) T-cell treatment, resulting in complete remission in 36 percent of the 101 patients in the trial. Since then, new gene-editing tools have improved on the CAR T cells, making them more effective at killing tumor cells.
CAR T cells are special white blood cells genetically altered to carry chimeric antigen receptors, which enable them to recognize and attack tumor cells that unmodified T cells will ignore in cancer patients. The T cells are filtered from the patient's blood, gene-modified to recognize cancer cells, then re-introduced to the patient's system where they go to work, according to Telegraph.
Looking for ways to improve on the CAR T-cell therapy that is currently having remarkable success in clinical trials, the Memorial Sloan Kettering Cancer Center has turned to a genome-editing technique using "clustered regularly interspaced short palindromic repeats" (CRISPR), prokaryotic deoxyribonucleic acid (DNA) fragments. Combined with smaller helper sequences called the CRISPR-associated system or CAS, the system called CRISPR/Cas can be used to create more potent T cells faster and with more precision, according to Cancer.gov.
Michael Sadelain, M.D., Ph.D. of Sloan Kettering have turned to a simpler variation of the CRISPR/Cas technique called CRISPR/Cas9 to address the difficulties with conventional approaches to engineering T cells, such as using a retrovirus. Instead of the random gene insertion points that characterize the usual methods, the new system can deliver the CAR gene fragment precisely where they need it — the T-cell receptor alpha chain (TRAC) gene.
The results are more effective batches of CAR T cells that are more stable than the conventionally engineered ones. "Expressing the CAR from the TRAC locus greatly diminished exhaustion, resulting in superior tumor eradication," Dr. Sadelain said.
This new development will further boost the exciting results of the CAR T-cell therapy currently on trial. Kite Pharma has published the result of their initial six-month trial of the new therapy, resulting in cancer remission for over a third of their subjects with aggressive non-Hodgkin's lymphoma.
"The numbers are fantastic," said Dr. Fred Locke, blood cancer expert and co-leader of the study. "These are heavily treated patients who have no other options," he continued.