Update on phase III study P301 of SPN 810 explains variability of Impulsive aggression control in ADHD.- Supernus Pharma

Supernus Pharmaceuticals has provided an update on the results from the first Phase III study (P301) of SPN-810, a novel treatment of Impulsive Aggression (IA) in patients with ADHD. In early November 2019, the Company reported topline results from the Phase III P301 trial in patients 6 to 11 years. The study was a randomized, double-blind, placebo controlled, multicenter, parallel group clinical trial in patients diagnosed with ADHD. Patients receiving SPN-810 36mg showed a median percent reduction of 58.6% in the average weekly frequency of impulsive aggression episodes from baseline that was not statistically significant (p=0.092) compared to placebo. These results are based on the combined analysis of data from stages 1 and 2 in the study. In stage 1 (interim analysis stage), the median percent reduction was 60.0%, which was statistically significant (p=0.029) compared to placebo. However, in stage 2 of the P301 study, post the interim analysis, the increase in variability in the 36mg treatment arm seems to have adversely impacted the results in the combined analysis.

After conducting further analysis on the P301 data, the Company believes that the high variability in the 36mg treatment arm was primarily due to 6 patients out of 135 that had a mild IA condition with a baseline score of 6 episodes or less per week. In the placebo arm, there were 7 patients with the same mild IA condition. By excluding these subjects from the placebo and the 36mg treatment arm, the primary analysis (combined stage 1 and 2 data) of the P301 data on the primary endpoint results in a p value of 0.017 for the treatment arm compared to placebo. This positive result is also confirmed by the sensitivity analysis on the primary endpoint with a p value of 0.044. The Company plans on finalizing the statistical plan (SAP) for the second Phase III P302 study in patients 6 to 11 years old taking into consideration the exclusion of patients with 6 or less episodes of IA per week. The Company will be submitting the SAP to the Food and Drug Administration (FDA) and expects data from the P302 study in the first quarter of 2020.