Incannex’s psychotherapy study delivers ‘significant’ benefits

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By Danica Cullinane - 
Incannex Healthcare ASX IHL psilocybin psychotherapy study significant benefits generalised anxiety disorder

Interim results from Incannex’s ongoing phase two trial has given it the confidence to start manufacture of its own psilocybin drug product.


Incannex Healthcare (ASX: IHL) has emerged from a trading halt with news that its psychotherapy program to treat generalised anxiety disorder (GAD) has achieved promising results in an ongoing phase two clinical trial.

The cannabinoid and psychedelic medicines company’s proprietary program is being developed to use psilocybin to improve the effectiveness of psychotherapy for GAD.

A review of interim data from the first 29 participants to complete the treatment protocol has indicated a high probability (greater than 85%) that the total study will show a “statistically significant benefit” for the psilocybin treatment arm over the placebo treatment arm.

A review was also conducted by an independent Data Safety Monitoring Board (DSMB), which identified no safety concerns to date and recommended no adjustments to the original study design or sample size.

Incannex chief executive officer and managing director Joel Latham said these interim results provide the company with encouragement that its “PsiGAD” psilocybin-assisted psychotherapy treatment protocol has the potential the transform the lives of people suffering from anxiety.

“Even though the results must remain blinded until the conclusion of the trial, the confidential review has given us the confidence to commence manufacture of our own psilocybin drug product with the appointment of Catalent, progress planning of our pivotal trials and commence drafting our FDA IND application for the PsiGAD treatment program,” he said.

Mr Latham noted that the clinical psychedelic lab at Monash University had overseen training of 14 psychotherapists to work on the phase two trial, demonstrating the treatment is scalable to many therapists and patients throughout the world.

To date, more than 45 participants have been enrolled in the study with 29 participants having completed the treatment protocol and main outcome assessment following treatment. Incannex anticipates treatment of a total of 72 participants is anticipated to be completed in the fourth quarter of 2023.

Inadequate current treatments for GAD

GAD, characterised by excessive anxiety and worry occurring over more days than not for at least six months, is a common disorder affecting millions of people around the world each year.

Symptoms include feelings of persistent and excessive worry, nervousness, restlessness, difficulty concentrating, and a range of somatic manifestations.

According to Incannex, current GAD treatments remain inadequate with less than half of patients achieving remission following evidence-based treatment, alongside high relapse rates and substantial treatment side effects or cost.

The ongoing PsiGAD trial

The psilocybin-assisted treatment arm of Incannex’s ongoing trial involves two administrations of psilocybin in conjunction with psychotherapy in a controlled clinical setting as part of a 10-week course of specialised treatment.

The projection made in these interim results assumes the effect size observed in the 29 participants is representative of the effect size through the remaining 43 participants.

The end point used in the modelling was a reduction in the Hamilton Anxiety Rating Scale (HAM-A) score at 11 weeks relative to baseline.

This scale consists of 14 items defined by symptoms and measures both psychic anxiety (mental agitation and psychological distress) and somatic anxiety (physical complaints related to anxiety).

According to Incannex, the HAM-A scale used for assessing GAD in this PsiGAD trial has been used to demonstrate the efficacy of other FDA-approved medications for the same indication including Lexapro, Paxil and Effexor XR.