Small Pharma Inc. announced further positive results from the Company's Phase IIa trial of SPL026, the first placebo-controlled study of a short-duration psychedelic for the treatment of Major Depressive Disorder. The trial investigated the efficacy and safety of a 21.5mg intravenous dose of SPL026, N,N-Dimethyltryptamine, with supportive therapy in 34 patients with moderate/severe MDD. Analyses of additional secondary and exploratory endpoints, including effects on self-reported depression, anxiety and wellbeing, demonstrated that patients receiving at least a single dose of IV SPL026 with supportive therapy experienced clinically relevant improvements in function and mood, further supporting previously announced topline efficacy results.

The two-staged study included a two-week blinded, randomized, placebo-controlled phase followed by a 12-week open-label phase, in which all participants received a single dose of SPL026. In January 2023 the Company reported that the Phase IIa trial met its primary endpoint with a statistically significant and clinically relevant reduction in depression symptoms at two-weeks post-dose, compared to placebo. SPL026 with supportive therapy also demonstrated a rapid onset and durable antidepressant effect, as assessed by the Montgomery-Asberg Depression Rating Scale.

Analysis of patient-reported depression scores corroborate the MADRS assessments conducted by independent clinical raters. Improvements in depression scores from baseline were observed across all study timepoints in patients receiving at least a single dose of SPL026, as measured by the Beck Depression Inventory, including a statistically significant improvement in depression symptoms compared to placebo at two-weeks post-dose (p=0.002). The efficacy outcomes on the BDI were consistent with MADRS, providing additional support for the rapid and sustained therapeutic profile of SPL026 for the treatment of MDD.

Measures assessing patients' anxiety and wellbeing, areas which are often negatively impacted by depression, were also analyzed across the study. Following both one and two doses of IV SPL026 with supportive therapy, patients demonstrated a rapid and sustained improvement in anxiety symptoms as measured by the State-Trait Anxiety Inventory-Trait scale. A statistically significant improvement in anxiety symptoms was observed compared to placebo at two-weeks post-dose (p=0.03).

At 12-weeks following the open-label dose, a -14.2 mean change from baseline was demonstrated in the patient group receiving the single dose regimen. Further, a rapid and sustained improvement in wellbeing was observed following at least a single treatment of IV SPL026 with supportive therapy, as measured by the Warwick-Edinburgh Mental Wellbeing Scale. The results at two-weeks following the blinded dose of SPL026 or placebo showed a 10.1 mean CFB in the SPL026 group compared to 0.9 in the placebo group.

Statistical analysis was conducted on the MADRS open-label data. A statistically significant difference in mean total MADRS score was observed for both the one and two dose regimen groups across all open-label study timepoints (p<0.05). Further analysis was conducted to assess the difference in total MADRS scores between the one and two dose regimen groups using a mixed model of repeated measures for all subjects across all timepoints.

No statistical difference (p=ns) was demonstrated between these dose regimens across all time points to 12-weeks. This analysis provides further support that a single dose of SPL026 is sufficient to elicit a rapid and durable antidepressant effect.