Parkinson’s gene therapy trial initiates third cohort

Written by RegMedNet

Safety and dosage of VY-AADC01 being explored in phase 1b trial

An ongoing Phase 1b open-label trial of a gene therapy for patients with Parkinson’s disease has announced dosing of the first patient in its third cohort.

Extensive research has identified death of dopamine neurons in the substantia nigra to be largely responsible for the progressive motor symptoms of Parkinson’s. These neurons are responsible for conversion of levodopa to dopamine, a process catalysed by AADC enzyme. When AADC levels are reduced in Parkinson’s patients, the body’s ability to convert oral levodopa to dopamine is impaired. The gene therapy being investigated in this trial being conducted by Voyager Therapeutics (MA, USA), VY-AADC01, comprises the adeno-associated virus-2 capsid and a cytomegalovirus promotor to drive AADC transgene expression. The therapy is designed to deliver the AADC gene directly into the putamen where the dopamine receptors are located, bypassing the substantia nigra neurons and enabling AADC enzyme expression in the putamen, where conversion of levodopa into dopamine can then occur.

Patients enrolled in cohorts 1 and 2 of the phase 1b trial have received a single administration of VY-AADC01 at a total dose up to of 7.5 × 1011 vector genomes (vg) and 1.5 × 1012 vg, respectively. Patients in cohort 3 will receive up to a three-fold higher total dose (4.5×1012 vg) versus cohort 2. The primary objective of this study is to assess VY-AADC01 safety at ascending dose levels, while secondary objectives include an assessment of the surgical coverage of the putamen and the assessment of AADC expression and activity in the putamen before and after treatment using 18-fluorodopa and PET.

“We are pleased with the progress of this ongoing Phase 1b trial and the initiation of the planned third cohort in this trial of up to 20 patients,” stated Voyager Therapeutics’ vice president of clinical development, Bernard Ravina. “Along with assessing safety, the goal of this open-label trial is to explore ascending dose levels and optimal delivery of VY-AADC01 in patients with advanced Parkinson’s disease. We remain on track to deliver six-month data on safety, motor function and biomarkers from patients in Cohort 1 and 2, as well as preliminary data from some patients in Cohort 3 by the end of this year. We will report longer-term safety and clinical data as we continue to advance the program next year.”

Written by Hannah Wilson

Source: Voyager Therapeutics Press Release