Incannex Healthcare Receives FDA Approval for Phase 2 Clinical Trial of Psilocybin Therapy

LOS ANGELES- Incannex Healthcare Inc. a clinical-stage pharmaceutical company, has received approval from the US Food and Drug Administration (FDA) to commence a Phase 2 clinical trial for its psilocybin pharmaceutical formulation, PSX-001, in combination with psychotherapy for patients with generalized anxiety disorder in the United States and the United Kingdom.

The FDA completed its review of Incannex’s Investigational New Drug (IND) application, submitted on June 26, 2024, within the designated 30-day period. The regulatory body has deemed the trial, named PsiGAD2, safe to proceed following an evaluation of the trial protocol, lead investigator, and a risk-benefit analysis of the trial and prospective drug product.

The PsiGAD2 trial will enroll approximately 94 patients with generalized anxiety disorder, including those currently treated with selective serotonin reuptake inhibitors, who meet the study’s inclusion and exclusion criteria. Participants will receive one of two dose strengths of PSX-001 under double-blind conditions, with two dosing sessions and additional preparatory and integration sessions to facilitate psychotherapy.

The primary endpoint for the study will be the change in the Hamilton Anxiety Rating Scale (HAM-A) score, a validated measure of anxiety, two weeks after the second dosing session. HAM-A scores will be collected at predefined intervals for 23 weeks post-dosing, with changes from baseline serving as secondary endpoints. Additional measures will include quality of life, healthcare utilization, electroencephalography (EEG) assessments, and monitoring of safety and tolerability through adverse event tracking.

PsiGAD2 builds on the positive results of PsiGAD1, a previous Phase 2 proof-of-concept trial conducted at Monash University. The earlier trial reported a 12.8-point reduction in HAM-A scores in the psilocybin treatment group, which was 9.2 points greater than the placebo group (p<0.0001). In PsiGAD1, 44% of patients in the psilocybin group experienced a greater than 50% reduction in HAM-A scores, and 27% achieved disease remission.

The PsiGAD2 trial is also under review by the Medicines and Healthcare Products Regulatory Agency (MHRA) in the United Kingdom. Incannex plans to conduct parallel startup activities for the trial in both the US and the UK.

Generalized Anxiety Disorder (GAD) is characterized by excessive anxiety and worry occurring more days than not for at least six months, unrelated to specific environmental circumstances. Symptoms include persistent worry, nervousness, restlessness, difficulty concentrating, and various somatic complaints. GAD often leads to significant distress and impairment in social, occupational, or other areas of functioning. The disorder has a lifetime prevalence of 6-9% and a 12-month prevalence of about 3% in countries like Australia and the United States. Treatment success remains inadequate, with less than half of patients achieving remission following evidence-based treatments, alongside high relapse rates and substantial treatment side effects or costs.