Voyager Therapeutics recently announced it is recruiting participants for the company’s phase 2 clinical trial testing the safety and effectiveness of the gene therapy VY-AADC02 in people with advanced Parkinson’s disease.

Gene therapy is a technique that involves inserting new DNA into a cell using a virus as a carrier or vector. In Parkinson’s, the DNA can help the cell to produce beneficial proteins that go on to help alleviate the motor features of the condition.

Voyager Therapeutics is a clinical-stage gene therapy company that is focused on treatments such as Parkinson’s. Voyager’s gene therapy product, VY-AADC01, carries a gene called AADC, an enzyme that converts L-dopa into dopamine. In September 2017 the company announced positive results from its Phase 1b trial of VY-AADC01. 

By injecting the virus carrying VY-AADC01 into the putamen of people with advanced Parkinson’s disease, Voyager is hoping to alleviate the motor features of the condition by allowing the brain to produce a constant supply of dopamine in the exact location that is missing the dopamine – the putamen is where dopamine is released in the brain. This approach will not cure the disease, but it may make life a lot easier for those affected by Parkinson’s.

The results of the Phase 1b trial suggested that the virus was well tolerated and resulted in increased AADC enzyme activity, enhanced response to L-dopa treatment, and clinically meaningful improvements in various measures of patients’ motor function (44% improvement in ‘off medication’ measures and 55% improvement in ‘on medication’ measures).

One of the most interesting results in the first study was the physician-rated motor examination which suggested that while cohort 1 on the lowest dose of VY-AADC01 treatment did not improve, the members of cohort 2 and 3 (the higher doses of the virus) demonstrated remarkable improvements.

The important point to remember in the first phase 1 trial of VY-AADC01 was that the study was ‘Open label’. This means that everyone involved (participants and clinicians) knew who was receiving the treatment. VY-AADC01 is now going to be tested in a double-blind fashion. 

The phase 2 clinical trial testing the safety and effectiveness of the gene therapy VY-AADC02 in people with advanced Parkinson’s is now recruiting patients at select sites in the U.S. Subjects involved in the Phase 2 study all have advanced Parkinson’s so it will be interesting to see trials which can potentially benefit later stage subjects.

Our ability to deliver genes to different locations shows just how far we have come with our understanding of the biology of Parkinson’s and gene therapy is one treatment approach which is very exciting.