Dyskinesia Trial Testing Dipraglurant Postponed Due to COVID-19

A Phase 2/3 trial (Study 301) testing Addex Therapeutic’s candidate dipraglurant for people with levodopa-induced dyskinesia associated with Parkinson’s disease (PD-LID) has been postponed — until further notice — due to the continued spread of COVID-19 in Europe and the U.S., where the trial was set to occur.

The intended patient population for this trial is among those with the highest risk for severe illness and death associated with the new coronavirus. As such, Addex is following the guidance of public health authorities that recommend people at high risk stay at home and avoid unnecessary exposure to COVID-19.

“As the situation with COVID-19 has evolved, we have stayed in close communication with study sites, vendors and colleagues and learned of new institutional precautions being put in place for clinical research,” Roger Mills, MD, chief medical officer of Addex Therapeutics, said in a press release.

“Sites are temporarily suspending on-site visits for monitors, vendors, and all other non-patient visitors and several sites have cancelled all non-essential patient visits,” Mills said.

“Priority is now rightly being placed on how to manage regular care for patients in the light of the increasing COVID-19 containment requirements,” he said. “We care about the well-being of all PD patients and do not wish to have them make the additional visits to doctors’ offices that are required in a clinical study, putting them at increased risk of contracting COVID-19.”

One of the gold standards in Parkinson’s treatment has long been therapy with levodopa, or L-DOPA — a precursor to the neurotransmitter dopamine, the increasing loss of which is a hallmark of the disease. However, levodopa therapy can lead to uncontrollable movements, a condition called levodopa-induced dyskinesia, or LID.

Dipraglurant is a new oral small molecule that inhibits the metabotropic glutamate receptor 5 (mGluR5), which has been shown to play a role in LID. The candidate therapy has a pharmacokinetic profile — meaning, its absorption, distribution, metabolism, and excretion in the body — that mimics the profile of levodopa, making it a potential treatment for LID.

The previous Phase 2 ADX48621-201 trial (NCT01336088) assessed the safety and tolerability of dipraglurant in 76 people with Parkinson’s and moderate-to-severe LID. The participants were randomly assigned to receive dipraglurant (from 50 mg once daily to 100 mg three times daily, 52 patients) or a placebo (24 patients).

The results showed that dipraglurant was in general safe. Moreover, it reduced PD-LID clinical symptoms, as measured by the modified Abnormal Involuntary Movement Scale, on day 1 (50 mg) and on day 14 (100 mg), and across a three-hour post-dose period on day 14. Treatment with dipraglurant did not worsen Parkinson’s symptoms.

Addex is continuing to work with the study sites to continue preparations so as to start the study as soon as it is “appropriate to do so.”