A novel gene therapy to improve symptoms in Parkinson's disease is being trialled by researchers in London and Paris.
Parkinson's disease is a neurodegenerative condition characterised by progressively worsening motor impairments such as rigidity, tremor and balance problems. The symptoms are related to a decreased level of dopamine, an important neurotransmitter (a chemical messenger that transmits signals across brain cells). This is caused by a loss of dopamine-producing neurons in the part of the brain involved in motor functions, the substantia nigra.
The treatment, called AXO-Lenti-PD, was developed by biotech companies Axovant and Oxford Biomedica. It aims to boost dopamine levels by delivering genetic instructions into the striatum of the brain where dopamine from substantia nigra is normally released. This is achieved by surgically injecting these cells with an inactivated virus that contains three genes involved in making dopamine.
'Genes that increase the production of dopamine could help alleviate the symptoms of Parkinson's disease, potentially with fewer side effects than traditional drug treatments, by targeting only the areas of the brain that are lacking in dopamine,' said Professor Thomas Foltynie at University College London Hospital and a lead clinician on the study.
'While we do not yet know if it is effective, it is hoped this therapy will provide patient benefit for many, many years following a single treatment,' he added.
The precise delivery of the gene therapy may also limit the undesirable side effects of current therapies. It is important to note, however, that the therapy aims to improve the symptoms but does not slow down the progression of the disease.
The clinical trial of about 30 patients with Parkinson's disease will first evaluate the safety and tolerability of different doses in patients at hospitals in London, Cambridge and Paris. These findings will then inform the second stage of the study, where the researchers will look at the long-term effects of the therapy on motor functions, compared with a sham surgery to exclude potential placebo effects. The preliminary results from the first part of the study are expected in 2019.