Psilocybin-assisted therapy may significantly reduce anxiety scores in phase 2 trial

The trial met its primary endpoint, demonstrating a large clinical effect in the psilocybin treatment group over the placebo group.

The trial protocol and treatment design were developed in partnership with the Clinical Psychedelic Lab at Monash University, led by Dr Paul Liknaitzky.

The reduction in HAM-A score from baseline in the psilocybin group was 12.8 points, from 29.5 at baseline to 16.8 at week 11 (6 weeks following the final dosing session), representing a decrease of 9.2 points over the placebo group (-12.8 psilocybin vs. -3.6 placebo; p<0.0001). 44% of patients in the psilocybin group showed a clinically meaningful improvement of at least 50% reduction in anxiety score from baseline; a ‘response rate’ more than four times higher than that of the placebo group. 27% of patients in the psilocybin group achieved full disease remission; a rate more than five times higher than that of psychotherapy with placebo.

Psilocybin within the context of PsiGAD psychotherapy was observed to be well-tolerated, with only mild and moderate adverse events (AEs) reported. The reported AEs were consistent with the known effects of the drug. No serious or severe adverse events were observed. Only one person of the 73 participants withdrew from the trial during the 7-week treatment program.

“We are thrilled with the results from our initial PsiGAD trial,” said President and CEO Joel Latham. “This is the first time psilocybin has been investigated for treatment of generalised anxiety disorder, and the reduction in HAM-A scores we have observed are far greater those reported from trials on established medicines for treatment of anxiety. The improvement in anxiety scores in PsiGAD1 are of a similar magnitude to the change seen in studies investigating psilocybin for treatment of depression disorders. Safety is a key component of any new therapy, and we are delighted that no serious or severe adverse events were observed in PsiGAD patients, which is testament to the focus on safety within the PsiGAD treatment protocol. The safety and efficacy results from PsiGAD1 implore us to continue the development of PsiGAD through large scale well-controlled trials, because this treatment method has the potential to improve the quality of life for millions of people suffering from generalised anxiety disorder.”

Incannex have designed the follow-up Phase 2B clinical trial, PsiGAD2, with the assistance of Clerkenwell Health, a UK based contract research organisation specialising in psychiatry and CNS treatments. This trial will be conducted at multiple sites in the United States (US) and United Kingdom (UK).

In parallel, Incannex has finalised the development of formulation of its psilocybin drug product, PSX-001. Final preparations for the manufacture of the cGMP clinical trial supply of PSX-001 are underway. Documentation on the formulation development and cGMP manufacture will form the final pieces of the FDA IND application that Incannex commenced in August of 2023. Clearance of the IND by the agency is required for the Company to conduct the PsiGAD2 study at sites in the US.

Incannex is continuing to work with Clerkenwell Health to select trial sites and prepare the relevant regulatory documents for submission to the Medicines and Healthcare products Regulatory Agency (MHRA) in the UK.

About Generalised Anxiety Disorder

Generalised Anxiety Disorder (GAD) is characterised by excessive anxiety and worry that occurs more days than not for at least 6 months and is not restricted to any particular environmental circumstances. Symptoms are variable, including feelings of persistent and excessive worry, nervousness, restlessness, difficulty concentrating, and a range of somatic manifestations. People with GAD find it difficult to control their worry, which may cause significant distress and impairment in social, occupational, or other areas of functioning. GAD is a relatively common disorder (about 6-9% lifetime prevalence, and about 3% 12-month prevalence in countries like Australia and the United States). As with other mood disorders, successful treatment of GAD remains inadequate, with less than half of patients achieving remission following evidence-based treatment, alongside high relapse rates, and substantial treatment side-effects or cost.