PHILADELPHIA (CBS) — A new gene therapy developed by a team at the University of Pennsylvania shows unprecedented success in curing leukemia.

Two of the three patients who received the treatment a year ago are still cancer-free.

Dr. David Porter is on the team that developed the treatment, which involves engineering the patients’ T-cells to seek and destroy leukemia cells, then injecting them back into the patient’s immune system.

“I don’t think any of us anticipated how dramatically this was going to work and how rapidly this was going to work,” said Dr. Porter.

The first patient developed complications within two weeks because his body was processing so many dead cancer cells and a few days later tests revealed he was cancer free.

“We were excited, I think we were all incredibly energized and absolutely thrilled for the patients.”

A second patient had similar succes, the third had dramatic but not complete reduction of the leukemia. The team hopes to treat more patients in the coming months.

Reported by Pat Loeb, KYW Newsradio