Inhibikase’s setback continues biopharma’s losing streak against Parkinson’s, marked by several clinical failures and abandoned assets in recent months.
Inhibikase Therapeutics on Wednesday announced that it will suspend the further development of its investigational drug risvodetinib in Parkinson’s disease.
The decision was spurred by underwhelming findings from a Phase II trial, which the biotech in an SEC filing said met its primary efficacy endpoint of safety and tolerability but failed to demonstrate significant efficacy. Inhibikase provided limited data in its regulatory document, but promised to present a more complete readout and analysis at a future medical congress.
In a hierarchy of 15 functional endpoints, risvodetinib failed to elicit a significant improvement in the top measure, which was the sum of scores in parts 2 and 3 of the Movement Disorder Society Universal Parkinson’s Disease Rating Scale (MDS-UPDRS).
Still, Ironwood flagged certain promising signals of efficacy. Patients treated with 100 mg risvodetinib saw a 1.41-point improvement in part 2 of the MDS-UPDRS, an effect with a nominal p-value of 0.036, according to the biotech. Meanwhile, the 50-mg dose led to a 4% increase in the results of the Schwab & England Activities of Daily Life Scale, a treatment effect with a nominal p-value of 0.0004.
With risvodetinib paused, Inhibikase is switching its focus to its new lead program IkT-001Pro, which it is developing for pulmonary arterial hypertension. The biotech will look at potential strategic options for risvodetinib but has yet to specify possibilities such as licensing deals or a sale. Aside from Parkinson’s, Inhibikase was also trialing risvodetinib for neurogenic constipation, dysphagia and multiple system atrophy.
Inhibikase’s stock price declined more than 19% in after-hours trading at $2.26 per share, down from $2.80 at the previous close.
Risvodetinib’s discontinuation highlights the difficulties of developing effective therapies for Parkinson’s disease, a therapeutic space that has suffered several stumbles and even more abandoned assets in recent months.
Last month, for instance, Roche disclosed that its Prothena-allied prasinezumab failed a Phase IIb Parkinson’s study, unable to significantly slow motor progression in patients. Just days earlier, Novartis and UCB announced that their drug candidate minzasolmin likewise failed a proof-of-concept Parkinson’s study.
Fellow Big Pharma Johnson & Johnson has also struggled with Parkinson’s, revealing in October 2024 that it would no longer invest in JNJ-0376, an early-stage drug candidate that, according to an earlier business presentation, had “novel mechanisms to modify, treat and/or prevent neurodegenerative disorders.”
In April of the same year, Sage Therapeutics was also forced to turn its back on its Parkinson’s program for the oral asset dalzanemdor after a mid-stage study found no significant cognitive improvements in treated adult patients.
