Story highlights Kymriah works by genetically modifying a patient's own cells so they can attack the cancer

An advisory committee recommended the drug for approval in July

(CNN) The US Food and Drug Administration approved a new leukemia treatment, which the agency considers the first gene therapy it has cleared to hit the market in the United States.

The treatment, called Kymriah, aims to give some patients a second chance after first-line drugs have failed. This may happen in up to a fifth of patients, according to the FDA.

Each dose of Kymriah contains a patient's own immune cells, which are sent to a lab to be genetically modified using a virus. This therapy -- known as chimeric antigen receptor T-cell therapy, or CAR-T -- gives the cells the ability to recognize and kill the source of the cancer.

"We're entering a new frontier in medical innovation with the ability to reprogram a patient's own cells to attack a deadly cancer," FDA Commissioner Dr. Scott Gottlieb said in a statement

"We've never seen anything like this before and I believe this therapy may become the new standard of care for this patient population," said Dr. Stephan Grupp, director of cancer immunotherapy at Children's Hospital of Philadelphia, which spearheaded this research.

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