Inhibikase Halts Parkinson's Drug Development Amid Industry Setbacks

Inhibikase Therapeutics has announced the suspension of further development for its investigational Parkinson's disease drug, risvodetinib, following disappointing results from a Phase II clinical trial. This decision marks another setback in the pharmaceutical industry's ongoing struggle to develop effective treatments for Parkinson's disease.

Phase II Trial Results and Decision

The Phase II trial for risvodetinib met its primary endpoint of safety and tolerability but failed to demonstrate significant efficacy. In a hierarchy of 15 functional endpoints, the drug did not show 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).

Despite the overall disappointment, Inhibikase reported some promising signals of efficacy:

• Patients treated with 100 mg of risvodetinib saw a 1.41-point improvement in part 2 of the MDS-UPDRS, with a nominal p-value of 0.036.
• The 50-mg dose led to a 4% increase in the results of the Schwab & England Activities of Daily Life Scale, with a nominal p-value of 0.0004.

Following this setback, Inhibikase is shifting its focus to IkT-001Pro, its new lead program for pulmonary arterial hypertension. The company will explore strategic options for risvodetinib, which was also being trialed for neurogenic constipation, dysphagia, and multiple system atrophy.

Industry-wide Challenges in Parkinson's Drug Development

Inhibikase's decision to halt risvodetinib's development is part of a broader trend of difficulties in the Parkinson's disease therapeutic space. Several major pharmaceutical companies have faced similar challenges in recent months:

1. Roche reported that prasinezumab, developed in collaboration with Prothena, failed a Phase IIb study, unable to significantly slow motor progression in Parkinson's patients.

2. Novartis and UCB's drug candidate, minzasolmin, failed a proof-of-concept Parkinson's study.

3. Johnson & Johnson announced in October 2024 that it would no longer invest in JNJ-0376, an early-stage drug candidate for neurodegenerative disorders.

4. Sage Therapeutics abandoned its Parkinson's program for dalzanemdor in April 2024 after a mid-stage study found no significant cognitive improvements in treated adult patients.

These setbacks underscore the complexity of Parkinson's disease and the challenges faced by researchers in developing effective treatments. As the industry continues to grapple with these obstacles, the need for innovative approaches and renewed focus on understanding the disease mechanisms becomes increasingly apparent.