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Inhibikase Halts Parkinson's Drug Development Following Phase II Trial Setback

• Inhibikase Therapeutics discontinues development of risvodetinib for Parkinson's disease after Phase II trial fails to show significant efficacy despite meeting safety endpoints.

• While the drug showed modest improvements in specific measures, including a 1.41-point improvement in MDS-UPDRS Part 2 scores at 100mg dosage, it failed to meet the primary functional endpoints.

• The company will pivot to focus on IkT-001Pro for pulmonary arterial hypertension, marking another setback in the challenging landscape of Parkinson's drug development.

Inhibikase Therapeutics announced Wednesday the suspension of its investigational Parkinson's disease drug risvodetinib, following disappointing results from a Phase II clinical trial. The decision triggered a significant market response, with the company's stock declining over 19% in after-hours trading to $2.26 per share.
The Phase II trial results revealed a mixed picture of the drug's performance. While risvodetinib met its primary safety and tolerability endpoints, it failed to demonstrate significant efficacy across the key functional measures. The trial evaluated multiple endpoints, with particular attention to the Movement Disorder Society Universal Parkinson's Disease Rating Scale (MDS-UPDRS).

Detailed Trial Outcomes

Despite the overall disappointing results, some secondary measures showed promise. Patients receiving 100mg of risvodetinib demonstrated a 1.41-point improvement in Part 2 of the MDS-UPDRS, achieving a nominal p-value of 0.036. Additionally, the 50mg dosage group showed a 4% improvement in the Schwab & England Activities of Daily Life Scale, with a notable nominal p-value of 0.0004.

Strategic Pivot and Market Impact

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

Broader Industry Context

This development adds to a series of recent setbacks in Parkinson's disease drug development. Notable failures include:
  • Roche and Prothena's prasinezumab, which failed to significantly slow motor progression in a Phase IIb study
  • Novartis and UCB's minzasolmin, which did not meet expectations in a proof-of-concept study
  • Johnson & Johnson's decision to discontinue investment in JNJ-0376, an early-stage neurodegenerative disorder candidate
These consecutive setbacks underscore the significant challenges in developing effective treatments for Parkinson's disease, highlighting the complexity of targeting this neurodegenerative disorder.
The company plans to present a more comprehensive analysis of the trial data at an upcoming medical congress, which may provide additional insights into the drug's performance and potential future applications.
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