The complexity of the treatment, involving the harvesting the patient cells and the subsequent genetic editing, is undoubtedly time-consuming and labor-intensive, so it remains to be seen how widely this kind of customized gene therapy could be rolled out.
The drug was one of several CAR-T therapies rushing to be the first to market.
About 15 percent to 20 percent of patients with B-cell ALL have cancer that either did not respond to treatment or has recurred, the FDA says. The approval was based largely on a trial in 63 severely ill children and young adults who had a remission rate of 83 per cent within three months - a high rate, given that relapsed or treatment-resistant disease is often quickly fatal.
Wednesday's announcement will "change the face of modern medicine and drug development", FDA Commissioner Dr. Scott Gottlieb said at a news briefing.
Doctors remove T cells from each cancer victim and ship the material to its factory in Morris Plains, New Jersey.More news: Alexa has a new friend: Cortana
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Dr. Kevin Curran, a pediatric oncologist at Memorial Sloan Kettering Cancer Center in NY, noted the treatment's high cost. "The lessons learned from the clinical trials of auto T-cell operations will assist us in being able to provide to the larger population".
"We're excited and proud to have moved this vehicle therapy, in collaboration with Novartis and CHOP, through all phases of development and clinical trials, established its efficacy, and now extended its reach to children across the country under this FDA approval", he added.
Patients who do not respond to the treatment within the first month would not be expected to pay, he told reporters.
The breakthrough has been welcomed by Australian medical practitioners and researchers as a promising sign not only for leukaemia, but for the future treatment of many other forms of cancer. Salvage therapies for children with relapsed ALL are highly toxic and only work in about 50 percent of relapsed patients.
However, Kymriah comes with the potential for severe side effects.
The one-time treatment has a boxed warning for cytokine release syndrome or CRS, a life-threatening side effect that can cause blood pressure to drop dangerously low.
Novartis points out that some groups think the company could actually have charged more for Kymriah. According to him, a price of $475,000 per treatment was "excessive".
His current research is focused on similar reprogramming of cells but for the detection of lung cancer cells.
"Before that, it may be that Australian patients travel overseas to access the therapy".