Irlab's shares plummet 60% after Ipsen-partnered Parkinson's drug flunks phase 2 trial

Irlab Therapeutics' stock has cratered after the Swedish biotech reported that its Ipsen-partnered Parkinson’s therapy failed to reduce involuntary body movements in a phase 2b trial.

The therapy, dubbed mesdopetam, failed to hit the primary endpoint of a clinically significant reduction in the number of hours participants with Parkinson’s experienced dyskinesia, a term for involuntary, erratic, writhing movements of the face, arms, legs or trunk.

Searching for positives, Irlab pointed to “significant anti-dyskinetic effects” as measured by a secondary endpoint for one of the dose levels across the 12-week study as well a broadly similar rate and nature of adverse events as seen in the placebo cohort.

CEO Richard Godfrey pointed to the secondary endpoint as evidence that it's too early to give up on mesdopetam. “Clearly, further detailed analysis is required to fully understand the potential of this first-in-class compound,” Godfrey said in a release Tuesday afternoon.

Investors didn’t appear placated, however, sending the company’s stock plummeting over 60% to 15 Swedish krona as the Stockholm stock exchange opened this morning. It’s a sudden fall from grace for the biotech, which had managed to maintain its share price in the thirties for the previous year.

It’s also bad news for Ipsen, which dished out $28 million upfront for the worldwide rights to mesdopetam back in 2021. The French pharma was due to take over phase 3 duties and all other remaining clinical development and global commercialization responsibilities should the treatment get the green light.

The therapy was being tested in Parkinson’s patients who have been treated for five years and are experiencing dyskinesia as a side effect of the widely used medicine levodopa. About 40% to 50% of people living with the disease experience this side effect, according to Irlab.

“Although the study did not meet its primary efficacy endpoint, a well-established scale used to assess dyskinesia, the UDysRS, demonstrated anti-dyskinetic effects by mesdopetam,” Irlab’s head of R&D Nicholas Waters pointed out in the release. “Notably, these anti-dyskinetic properties were obtained without impairing normal motor function and are further strengthened by an apparent reduction in OFF-time.”

One of the aims of the study had been to select the best dose from a range of 2.5 mg, 5 mg and 7.5 mg. The company now has a “clear understanding” that 7.5 mg is the ideal dose for further trials, Waters added.

Irlab can take some comfort from the fact that it is far from alone in struggling to get a Parkinson’s disease to market. In the past year alone, Inhibikase Therapeutics’ midstage drug was slapped with an FDA hold, Kyowa Kirin axed its own candidate, Addex Therapeutics halted a phase 2b/3 study and AbbVie terminated its Parkinson’s-focused collaboration with BioArctic.

Even if mesdopetam falls flat, Irlab still has one other Parkinson’s disease treatment in the clinic, called pirepemat. The therapy is undergoing phase 2 studies for falls and dementia related to the disease.