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Immune cells called T cells attack a cancer cell.

Rita Elena Serda, Duncan Comprehensive Cancer Center at Baylor College of Medicine, NCI, NIH

Modified T cells that attack leukemia become first gene therapy approved in the United States

The U.S. Food and Drug Administration (FDA) today approved a new cancer therapy that involves genetically modifying a patient’s immune cells. The agency called the decision a “historic action” because the therapy, developed by Novartis, is the first gene therapy treatment approved in the United States.

The new treatment involves removing immune cells called T cells from a patient’s blood and giving them a gene for a protein called a chimeric antigen receptor, or CAR, that directs the T cells to target leukemia cells. The modified cells are then transfused back. Although the treatment sometimes causes severe side effects, in a Novartis clinical trial the drug caused remission in 83% of 63 young patients with a certain type of leukemia, B cell acute lymphoblastic leukemia (ALL).

FDA approved the Novartis drug, called Kymriah (tisagenlecleucel), for children and adults up to age 25 with B cell ALL who have not responded to conventional therapy or who have relapsed. About 3100 people under age 21 are diagnosed with ALL each year in the United States, though most respond to standard therapy.

The FDA decision was expected after an agency advisory panel met in July to discuss the risks and benefits of the Novartis treatment. Panelists raised some safety concerns, but voted unanimously to recommend approval.

Along with the excitement surrounding CAR-T cells, which are being developed by several companies, there are worries about pricing—the Novartis drug will cost $475,000, although that is reportedly less than expected. Supply is also a concern. The modified cells must be made specifically for each patient in special production facilities, and, in clinical trials, shortages have already arisen at some medical centers.

FDA could approve a CAR-T cell therapy for a form of lymphoma later this year. Researchers are trying to get the approach to work for solid tumors.

Although China has approved a gene therapy cancer drug and two gene therapy treatments for inherited genetic diseases are on the market in Europe, this is the first to win approval from FDA. The first gene therapy to gain FDA approval for an inherited disease could be a treatment for a form of blindness.