LONDON - An experimental drug could offer hope for restoring damaged brain cells in Parkinson's patients, scientists said on Wednesday, although they cautioned that a clinical trial was not able to prove the treatment slowed or halted the neurodegenerative disease.
The trial involved delivery of a protein therapy directly into the brains of Parkinson's patients. Scientists said some brain scans revealed "extremely promising" effects on damaged neurons of those who received the treatment.
"The spatial and relative magnitude of the improvement in the brain scans is beyond anything seen previously in trials," said Alan Whone, a Parkinson's specialist at Britain's Bristol University who co-led the trial.
Researchers said the therapy warranted further investigation even though it failed to demonstrate improvement of symptoms in patients who received it when compared to others given a placebo.
"The primary outcome was disappointing," Whone told reporters at a briefing in London.
Parkinson's is a neurodegenerative disease that affects around one percent to two percent of people over age 65. It causes tremors, muscle stiffness and movement and balance problems. Although some medicines can improve symptoms, there is no cure or treatment that can slow progression of the disease.
This trial involved 41 patients who all underwent robot-assisted surgery to have tubes placed into their brains.
That allowed doctors to infuse either the experimental treatment - called Glial Cell Line Derived Neurotrophic Factor (GDNF) - or a placebo directly to the affected brain areas. GDNF is made by privately-held Canadian biotech firm MedGenesis Therapeutix.
Half of the patients were given monthly GDNF infusions and half received monthly placebo infusions. After nine months, all participants were offered the GDNF infusions for a further nine months.
Results showed some signs of improvements, Whone said, but there was no significant difference between the treatment and placebo groups. He said this was in part due to the sizeable placebo effect in this trial.
The placebo effect has been known to confound clinical trials of treatments for conditions involving the brain, boosted by patients' expectations that a potential treatment will work.
But the brain scan results suggested the drug might be starting to reawaken damaged brain cells. After nine months, there was no change in the scans of patients who received a placebo, but those who got GDNF showed major changes in a key area of the brain affected by the disease.
Whone said this suggested GDNF could be "a means to possibly reawaken and restore" brain cells that are gradually destroyed in Parkinson's.