Novartis had received a trifecta of designations that helped speed approval: the FDA gave fast-track, breakthrough therapy, and priority review status to tisagenlecleucel's application.
In a key study of 63 advanced patients, 83 percent went into remission soon after receiving the CAR-T cells. It is the first gene therapy to be allowed in the United States - a "historic" approval, the agency said.
XAutoplay: On | OffKymriah, a cell-based gene therapy, was approved to treat patients up to age 25 with what's called B-cell acute lymphoblastic leukemia.
This type of immunotherapy, known as a CAR-T cell therapy, was known by the term CTL019 until now.
Beyond the cost of the procedure, patients would need to pay for traditional chemotherapy, which is given before auto T-cell therapy to improve its odds of success.
The Switzerland-based company said the drug will cost nothing if patients fail to benefit in the first month.
In clinical trials, CAR-T therapies have shown remarkable efficacy against blood cancers.
"We're entering a new frontier in medical innovation with the ability to reprogram a patient's own cells to attack a deadly cancer", said FDA Commissioner Scott Gottlieb, who was appointed to the position by President Donald Trump earlier this year.
"Five years ago, we began collaborating with the University of Pennsylvania and invested in further developing and bringing what we believed would be a paradigm-changing immunocellular therapy to cancer patients in dire need", Novartis CEO Joseph Jimenez said in a statement.
Because patients can develop life-threatening side effects weeks after the procedure, doctors will ask patients to stay within two hours of the hospital for up to a month. Auto T-cell therapies can damage healthy immune cells, including the cells that produce the antibodies that fight disease. The others still are being tracked to see how they fare long-term. Novartis already is facing pressure from patient advocates about the expected cost. In the US, only a few dozen specialized hospitals are now qualified to provide CAR-T treatments, which require retrieving, processing and then returning immune cells to the patient.
Of course, plenty of questions remain as CAR-T use is just ramping up, but leaders in the field have made progress with manufacturing and logistical problems lately, as well as safety, which previously plagued Juno Therapeutics.
Potential side effects of Kymriah include cytokine release syndrome, a bodily response characterized by high fever and flu-like symptoms.
Other genetic therapies for cancer are also in the research pipeline.