breakthrough cancer treatment approved

Opening a new era in cancer care, U.S. health officials on Wednesday approved a breakthrough treatment that genetically engineers patients' own blood cells into an army of assassins to seek and destroy childhood leukemia.

The Food and Drug Administration called the approval historic, the first gene therapy to hit the U.S. market. Made from scratch for every patient, it's one of a wave of "living drugs" under development to fight additional blood cancers and other tumors, too.

Novartis Pharmaceuticals set the price for its one-time infusion of so-called "CAR-T cells" at $475,000, but said there would be no charge for patients who didn't show a response within a month.

"This is a brand new way of treating cancer," said Dr. Stephan Grupp of Children's Hospital of Philadelphia, who treated the first child with CAR-T cell therapy — a girl who'd been near death but now is cancer-free for five years and counting. "That's enormously exciting."

CAR-T treatment uses gene therapy techniques not to fix disease-causing genes but to turbocharge T cells, immune system soldiers that cancer too often can evade. Researchers filter those cells from a patient's blood, reprogram them to harbor a "chimeric antigen receptor" or CAR that zeroes in on cancer, and grow hundreds of millions of copies. Returned to the patient, the revved-up cells can continue multiplying to fight disease for months or years.

It's a completely different way to harness the immune system than popular immunotherapy drugs called "checkpoint inhibitors" that treat a variety of cancers by helping the body's natural T cells better spot tumors. CAR-T cell therapy gives patients stronger T cells to do that job.

"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.

In a key study of 63 advanced patients, 83 percent went into remission soon after receiving the CAR-T cells. Importantly, it's not clear how long that benefit lasts: Some patients did relapse months later. The others still are being tracked to see how they fare long-term.

Still, "a far higher percentage of patients go into remission with this therapy than anything else we've seen to date with relapsed leukemia," said Dr. Ted Laetsch of the University of Texas Southwestern Medical Center, one of the study sites. "I wouldn't say we know for sure how many will be cured yet by this therapy. There certainly is a hope" that some will be.