By Stephanie Stahl

PHILADELPHIA (CBS)–A first-of-its-kind cancer treatment, developed here in Philadelphia, won a unanimous endorsement on Wednesday from FDA advisors.

Emily Whitehead was the first pediatric patient at Children’s Hospital to be treated with the immunotherapy treatment in 2012. She had relapsed twice with acute lymphoblastic leukemia.

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Doctors and researchers at CHOP developed the treatment called CAR-T. It involves removing immune cells from a patients’ blood, reprogramming them to create an army of attack cells and putting them back into the patient.

“A way of genetically engineering each patient’s immune system so it can go back and kill its own cancer cells,” said Dr. Stephan Grupp. “This is a brand new completely different a totally new way of treating cancer.”

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Dr. Grupp and his colleagues at CHOP have now treated more than 150 children with the experimental therapy. The results have been described as impressive.

Dr. Grupp and the Whitehead family were among those testifying before the FDA advisory panel, hoping to get the treatment approved.

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“They keep telling us that Emily is rewriting the history books because she was the first child in the world with the immune system trained to beat her leukemia,” said Tom Whitehead in January 2016.

Last year the Emily Whitehead Foundation donated $100,000 to CHOP’s cancer center

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“We were just hoping for anything because this was her last chance this was the only thing she had left,” said Kari Whitehead.

A grateful family giving back with their 12-year-old daughter–the history maker–who 5 years later remains cancer free.

The cost of CAR-T therapy is likely to be hundreds of thousands of dollars, and there can be some serious side effects. But it’s only given once.

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Researchers admit there are still a lot of unknowns about long term outcomes.

Stephanie Stahl