The trial patients were all in the early to early-mid stages of the disease and lived an average of 5.4 more years. At death, their brains were then autopsied.
"Up to this point, we hadn't known whether growth factors could effect degenerating neurons of Alzheimer's brains," said Mark Tuszynski, director of the Center for Neural Repair at the University of California-San Diego School of Medicine and the study's lead author. "All the 10 patients showed growth factor response. ... Cells that had clearly been in the process of dying were regrowing axons."
The results of the trial confirmed that the therapy was safe, which was the principal goal of the Phase 1 trial. But the bonus, Tuszynski said, was that the researchers learned "very unequivocally that degenerating neurons can respond."
What they did not learn, he said, was whether those restored neurons would improve the clinical symptoms of Alzheimer's patients. That's the focus of a phase 2 clinical trial currently taking place at the University of Southern California.
One of the upsides to gene therapy treatment is that it is targeted and can be restricted to specific, affected areas of the brain without damaging healthy cells nearby. But Tuszynski is also excited about the one-and-done aspect of the treatment.
"With gene therapy, the potential is you can go in and have a surgical procedure of three to four hours and have lifelong protection, without having to take a drug every day," he said. "If you know you have a disease that robs you of the essence of your intellect, will you undergo a three-hour operation? Pardon the expression, but that seems like a no-brainer."