A MeiraGTx Holdings gene therapy for Parkinson’s disease has preliminary data from a small clinical trial showing the one-time treatment showed both safety and efficacy, results that lay the groundwork for discussions with regulators about a Phase 3 study.
The MeiraGTx gene therapy, AAV-GAD, had previously posted Phase 1 and Phase 2 results showing it was well tolerated with no significant adverse effects. The results announced Tuesday are from a Phase 1 bridging study designed to evaluate doses of AAV-GAD manufactured by London-based MeiraGTx at its own facilities using its commercial platform process.
Parkinson’s patients lack sufficient amounts of a neurotransmitter called dopamine. Standard treatment includes the drug levodopa, a compound that a brain enzyme converts into dopamine. But dopamine replacement therapies lose efficacy over time. The motor symptoms of Parkinson’s can also be treated with deep brain stimulation, but that’s an invasive procedure.
MeiraGTx’s gene therapy is designed to spark local production of a neurotransmitter called GABA, which is intended to reprogram dysfunctional brain circuits and restore more normal activity to cells, alleviating motor symptoms. The 26-week bridging study enrolled Parkinson’s patients who had a history of responsiveness to levodopa treatment for at least 12 months. A total of 14 participants were randomly assigned to receive a high dose, a low dose, or a sham treatment.
According to MeiraGTx, AAV-GAD met the main goal of safety and tolerability with no serious adverse events (SAEs) reported. Efficacy, an exploratory endpoint, was evaluated by measuring motor examination scores. The company said at week 26, results show a statistically significant 18-point average improvement from baseline according to a rating scale used to measure the severity and progression of Parkinson’s. By comparison, no significant change was observed in the low-dose group or the sham cohort.
“With material made using our proprietary production process at commercial scale, we have demonstrated that AAV-GAD is safe at all doses studied, including a higher dose than previously tested,” MeiraGTx President and CEO Alexandria Forbes said in a prepared statement. “We have now treated a total of 58 patients in this development program in three independent multicenter clinical studies and have seen no SAEs related to AAV-GAD treatment.”
Participants who completed the bridging study have the option of enrolling in a long-term follow-up study, which will monitor them for five years. Meanwhile, MeiraGTx said it plans to discuss the results with regulators in the U.S., Europe, and Japan as it looks ahead to pivotal testing of the gene therapy.
MeiraGTx isn’t the only company working to develop a one-time treatment for Parkinson’s. Bayer’s bemdaneprocel is made by engineering donor cells, turning them into dopamine-producing neurons. These cells are surgically transplanted into a patient’s brain where they are intended to replace a patient’s lost dopamine production. Last year, Bayer reported positive safety and efficacy data from bemdaneprocel’s Phase 1 test. Last month, Bayer reported these encouraging trends continued measured at 24 months.
Aspen Neuroscience is also developing a Parkinson’s cell therapy. But unlike Bayer’s approach, Aspen’s ANPD001 is made from stem cells sourced from a patient’s own skin, offering the potential to avoid immunosuppressive drugs needed to prevent the body from rejecting the transplanted cells. Last month, Aspen announced it had completed dosing of the first cohort of a Phase 1/2a test of this cell therapy.
Image: Dr_Microbe, Getty Images
