SAN ANTONIO, TX. (Ivanhoe Newswire) -- The most aggressive form of brain tumors has a new enemy. Gene therapy is giving doctors and patients high hopes.

“Oh, it’s just devastating. It’s like your life it's over," John Worch, a brain tumor patient, told Ivanhoe.

That’s the first thing that went through John Worch’s mind last April when he found out he had stage four glioblastoma, the deadliest kind of brain tumor. The elementary school principal, who also serves in the air national guard, had the three and a half inch tumor removed from his brain, but in February, it started growing back.

John got in touch with Dr. Andrew Brenner, who enrolled him into a first of its kind gene therapy study. As part of the one-time treatment, John was injected with a cold virus.

“Instead of the virus carrying its own DNA, it carries our engineered DNA,” Andrew Brenner, M.D., a neuro-oncologist at the University of Texas Health Science Center at San Antonio's Cancer Therapy & Research Center, said.

The doctor says the virus delivers that engineered gene to cells around the brain tumor, signaling them to die.

“It basically causes the tumor to starve. No nutrients. No oxygen,” Dr. Brenner said.

According to Dr. Brenner only three people in the world are taking part in the study.

“But of the patients who have been treated, none of them have had tumor growth,” Dr. Brenner said.

A promising sign, but Brenner says it’s too early to draw any conclusions.

“You hope as time goes on, the more it gets starved, the more it will shrink and die away,” Dr. Brenner said.

John says he feels better since the treatment. He hopes the innovative therapy will allow him to keep working with these children and be here for his own children.

“I’m hoping to see them grow up into adults and have their own families. That’s what I hope to see,” John said.

Dr. Brenner says so far, the three patients in the gene therapy study haven’t had any side effects. The doctor hopes to expand the study to include about 25 more brain tumor patients in the near future.