Current report 4/2025 – Phase II top – line results for CPL’ 36, a PDE10a inhibitor in the treatment of Dyskinesia in Parkinson’s disease

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In reference to current report 17/2024 regarding positive results of the Phase II clinical trial on a drug based on CPL'36, an innovative PDE10A inhibitor, in the treatment of schizophrenia, in which the Company informed about the simultaneous ongoing Phase II clinical trial of the use of this compound in patients with dyskinesia in Parkinson's disease, the Management Board of Celon Pharma S.A. (the "Company") announces positive Phase II results of this study.

This was multinational, multicenter, randomized, placebo controlled study in group of 105 adult patients with dyskinesia in Parkinson’s disease. CPL’36 was administered orally in two doses - 20mg and 40 mg, and compared with placebo (1:1:1) once daily for a period of 4 weeks. The baseline score of UDysRS (Unified Dyskinesia Rating Scale) for randomized patients was approximately 45 points, indicating they were moderately severe to severely ill.

At week 4, the improvement in UDysRS total score (designated as primary endpoint) at the dose 20 mg  was 12,30 units (LS Mean difference from placebo, p<0,001, Cohen’s d: 0,90) and improvement at the dose 40 mg was 13,58 units  (LS Mean difference from placebo, p<0,001, Cohen’s d: 1,00).

The CPL’36 demonstrated improvement in most secondary endpoints, including UDysRS objective subcale, in which the improvement in both active groups was statistically significant from Day 7 of the treatment phase, and afterwords.

CPL’36 was well tolerated. There were only few adverse events with severe intensity (8,8% in placebo group, 0% in 20 mg dose and 5,7% in 40 mg dose). Related treatment emergent adverse events leading to discontinuation of study medication were recorded in 2,9% in placebo group, 11,1% in 20 mg dose and 8,6% in 40 mg dose. There were no deaths.

One Serious Adverse Event was reported in 40 mg group, described as atrial fibrillation with moderate intensity. The most common adverse event reported in both active groups was somnolence with intensity from mild to moderate.

The study met all endpoints, exceeding significantly earlier Company’s medical assumptions. It demonstrated robust and consistent efficacy across all different scales suggesting positive effect of CPL’36 in the treatment of dyskinesia in Parkinson’s disease. The effect size was large.

This is the first clinical study demonstrating robust efficacy of PDE10A inhibition in the treatment of patients suffering from dyskinesia in Parkinson’s disease with positive primary and secondary endpoints readouts. In the Company opinion, its results should be seen as breakthrough milestone in Parkinson disease pharmacotherapy.