The $475,000 drug

The US Food and Drug Administration recently approved the first gene therapy, Kymriah, to treat B-cell acute lymphoblastic leukemia. It uses a lentivirus to modify the patient’s T cells to kill tumor cells. Acute lymphoblastic leukemia, or ALL, is caused by uncontrolled growth of B cells, which normally produce antibodies to fight off infections. It is the most common cancer in children. The uncontrolled production of these cells by the bone marrow causes a shortage of blood cell production, leading to fever, increased risk of infection, and anemia. These B cells have on their surfaces a protein called B19 – which is the key to understanding how Kymriah works. The therapy begins with drawing blood from the patient, from which T cells are purified. These T cells are then infected with a lentivirus vector that encodes the gene for a chimeric antigen receptor (CAR) that recognizes the B19 protein. The CAR protein is synthetic – it doesn’t exist in any cell. The extracellular domain consists of a single-chain antibody directed against the B19 protein (pictured). The cytoplasmic domain of the protein contains sequences that stimulate the T cells to proliferate. After the T cells are infected with the CAR-encoding lentivirus, they are infused back into the patient. Upon encountering a B cell producing B19, the T cells bind to the protein and kill the cells, thus eliminating the cancer. Kymriah was licensed by the FDA after testing showed it was effective, le...
Source: virology blog - Category: Virology Authors: Tags: Basic virology Information ALL B cell B-cell acute lymphoblastic leukemia B19 CAR chimeric antigen receptor gene therapy Kymriah lentivirus viral viruses Source Type: blogs