Scientists are reporting that the initial tests to treat leukemia by using the patient's own blood cells to destroy cancer tumors have been successful.

Researchers at the University of Pennsylvania published their findings in The New England Journal of Medicine and Science Translational Medicine. They engineered the patients' own pathogen-fighting T-cells to target the leukemia cells.

The two participants in the Phase I Trial are now in remission while a third had a strong anti-tumor response and his cancer remains in check. The researchers plan on treating four more patients before launching Phase II trials.

"It worked great; we were surprised it worked as well as it did," said Dr. Carl June, a gene therapy expert at the University of Pennsylvania and the study's lead researcher. "We're just a year out now. We need to find out how long these remissions last.

The researchers used a new technique that delivered new genes into the patients' white blood cells and added a signaling mechanism that orders the T-cells to kill cancer cells and multiply.

"We put a key onto the surface of the T-cells that fits into a lock that only the cancer cells have," said Dr. Michael Kalos, director of translational and correlative studies at the University of Pennsylvania's Perelman School of Medicine and an investigator on the study.

The results also offer future techniques that can target other forms of cancer including lung and ovary cancer.

While the technique seems to be effective an editorial in The New England Journal of Medicine urged caution and added that it was too soon to determine the therapy's effectiveness.

"One of the big questions is ... will those persistent T-cells continue to work and prevent that tumor from coming back," wrote Dr. Walter J. Urba, who was not involved in the study.

The researchers remain optimistic and are looking for corporate sponsors as they head into the Phase II trials.