Irlab moving on Phase 3 trial of mesdopetam to treat dyskinesia

After FDA meeting, envisions study in at least 200 patients with daily off times

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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Irlab Therapeutics is preparing to start a Phase 3 clinical trial of mesdopetam, its experimental oral treatment intending to ease levodopa-induced dyskinesia, the uncontrolled movements affecting people with Parkinson’s disease.

After announcing results of a Phase 2 trial of mesdopetam, Irlab requested an end-of-Phase 2 meeting with the U.S. Food and Drug Administration (FDA). At this type of meeting, the FDA reviews available data from previous trials and provides feedback on plans for future studies designed to support regulatory approval.

At this recent meeting, the FDA provided “positive feedback” and alignment on several key features of the planned Phase 3 trial, including the trial’s main efficacy measures, according to a company press release. Irlab now is planning to seek similar guidance from regulators in Europe before initiating a Phase 3 study in up to 250 Parkinson’s patients.

“Following the successful End-of-Phase 2 meeting for mesdopetam, we are now delighted to conclude that the FDA’s formal meeting minutes confirm our plans for Phase III and validate the quality of our development activities,” said Gunnar Olsson, CEO of Irlab.

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“It is gratifying to see that the extensive work carried out by Irlab’s experienced team meets the requirements of the regulatory authority to move mesdopetam into a confirmatory clinical Phase III program,” Olsson added.

Parkinson’s is caused by the death and degeneration of brain cells responsible for making the signaling molecule dopamine. Reduced dopamine signaling ultimately gives rise to most disease symptoms.

The gold standard treatment for Parkinson’s is levodopa, which basically works by giving the damaged cells more raw materials with which to make dopamine. Although levodopa can be potent for relieving Parkinson’s motor symptoms, its long-term use frequently leads to dyskinesia as a side effect.

Patients on long-term levodopa also frequently experience off periods, times where symptoms aren’t well controlled between scheduled doses.

Mesdopetam, formerly called IRL790, is designed to block the activity of the D3 receptor, a specific dopamine receptor that’s been linked with levodopa-induced dyskinesia.

Oral mesdopetam at high dose showed efficacy, safety in a Phase 2b trial

The prior Phase 2b study (NCT04435431) tested several doses of mesdopetam against a placebo in more than 150 Parkinson’s patients who were experiencing dyskinesia. The trial hoped to show the therapy could improve patients’ on time when symptoms are well controlled without dyskinesia. Although the treatment failed to meet that study goal, improvements in good on time were seen for those given the highest dose of mesdopetam, a 7.5 mg capsule taken twice daily.

Phase 2 results also showed a significant reduction in scores on the Unified Dyskinesia Rating Scale (UDysRS), a standardized measure of dyskinesia severity, in treated patients. Irlab reported that mesdopetam was well tolerated and showed reasonable safety.

The upcoming Phase 3 study plans to use the UDysRS (specifically, parts 1, 3, and 4 of this scale) as its main measure of efficacy in testing if mesdopetam can ease dyskinesia. Secondary outcomes will include other measures of symptom severity, as well as patient-kept diaries to assess good on time.

It is expected to enroll 200 to 250 patients who have dyskinesia for at least two hours per day, the same population enrolled in previous trials. Participants will be randomly assigned to either mesdopetam at 7.5 mg twice daily or to a placebo for about three months.

To meet FDA requirements for long-term safety data, the Phase 3 study also will include an extension phase where at least 100 patients will be treated with mesdopetam for at least one year.

Irlab had been developing the therapy in collaboration with Ipsen under a 2021 agreement. It secured full ownership of the mesdopetam program in August 2023, while agreeing to pay Ipsen royalties based on potential future sales.