Phase 2 Trial of Gene Therapy VY-AADC to Include More Parkinson’s Patients

José Lopes, PhD avatar

by José Lopes, PhD |

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The ongoing Phase 2 study of the gene therapy VY-AADC will enroll more Parkinson’s disease patients than originally planned, Voyager Therapeutics announced.

The company’s revised trial protocol will include more patients — up from 75 to 100 — in the RESTORE-1 Phase 2 clinical trial (NCT03562494). Voyager also is planning to conduct a parallel Phase 3 study named RESTORE-2, with similar size and design to RESTORE-1.

These updates result from a type B meeting the company had with the U.S. Food and Drug Administration (FDA) in December 2018 and from the written feedback Voyager got from the agency.

“Our recent meeting with the FDA was informative and helps to clarify the expected regulatory pathway for VY-AADC,” Andre Turenne, Voyager’s president and CEO, said in a press release. “We look forward to continuing to engage with the FDA and other regulators as we advance our clinical development program and our work to bring VY-AADC to patients in need,” he said.

Parkinson’s is characterized by progressive loss of dopamine-producing neurons in a brain area called substantia nigra, which is key in controlling movement. This leads to lower levels of dopamine in the putamen, a connected brain region that contains dopamine receptors.

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In Parkinson’s patients, the putamen also has markedly reduced levels of the enzyme AADC, which is required to convert levodopa — the gold standard treatment — into dopamine.

Voyager’s VY-AADC consists of a modified and harmless adeno-associated virus to deliver the DDC gene, thereby providing the instructions for making the AADC enzyme directly in the putamen.

RESTORE-1 is currently enrolling individuals diagnosed with Parkinson’s for four years or more and who are not responding well to oral medications. Eligible patients also need to have at least three hours of daily “off” periods — characterized by the return of motor and non-motor symptoms when levodopa’s effects wear off — as assessed by a self-reported patient diary.

Enrolled participants are then randomized to either one-time administration of VY-AADC or placebo surgery.

The double-blind trial’s primary efficacy endpoint, or goal, is on time without troublesome dyskinesia (involuntary, jerky movements), or good “on” time, as measured by a self-reported patient diary at 12 months. The scientists will continue following the patients beyond this timepoint to collect further safety data and to assess how long the therapy’s potential benefits last.

Secondary goals include assessing changes in response to levodopa and in activities of daily living assessed with the United Parkinson’s Disease Rating Scale (UPDRS-II), quality of life with the Parkinson’s Disease Questionnaire, and global function through the proportion of patients with improved Clinical Global Impression score.

The trial also will assess the treatment’s safety, as well as changes in non-motor symptoms with the Non-Motor Symptom Scale. As for biomarkers, the investigators will measure the extension of VY-AADC coverage of the putamen , and AADC enzyme expression and activity in this brain region. Changes in patients’ levodopa dose per day and related medications also will be analyzed.

The company anticipates that RESTORE-1 will take about 15 to 21 months to fully enroll. Recruitment for RESTORE-2 is planned in both active Phase 2 sites and other global locations in the first half of 2020. If positive, results from the Phase 2 and Phase 3 trials could be the basis for the submission of a biologics license application to the FDA covering VY-AADC, according to Voyager.

In June 2018, the FDA granted VY-AADC regenerative medicine advanced therapy (RMAT) designation for the treatment of therapy-resistant motor fluctuations in Parkinson’s patients.

This designation was based on the positive results of a Phase 1b trial (NCT03065192) in 15 Parkinson’s patients, which revealed improvements in motor function and marked reductions in daily use of levodopa and other medications upon treatment with VY-AADC.