Diamond Therapeutics plans to run a Phase II trial for anxiety with an interesting twist: patients will self-administer low doses of the psychedelic psilocybin at home.
Toronto, Canada-based Diamond Therapeutics will initiate the four-week trial in late 2023 or early 2024, enrolling 40 patients with generalized anxiety disorder, CMO Dr. Michael McDonnell tells Clinical Trials Arena. Patients will receive one week’s worth of psilocybin doses at a time, with weekly follow-ups to ensure compliance and distribute subsequent doses, he adds.
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By GlobalDataOn January 24, Diamond Therapeutics announced that Health Canada had approved plans for the Phase II study based on established safety and tolerability in a previous Phase I study. Despite the trial’s unique take-home dosing regimen, McDonnell says there were not any significant challenges to gaining the regulatory go-ahead.
The biotech is only administering small numbers of psilocybin doses unlikely to cause any hallucinogenic effects, which alleviated Health Canada’s primary concerns of dose distribution, McDonnell explains. “The total combined weekly dose in the Phase II trial is reasonably low, even if someone, for unknown reasons, decided to take the entire week all at once,” he adds.
Psilocybin, which is the main psychoactive ingredient found in psychedelic ‘magic mushrooms,’ has been linked to improvement in several mental health conditions during early clinical research. However, there has been limited research on low-dose or micro-dose psychedelic approaches to anxiety disorders, which McDonnell says was the impetus for Diamond Therapeutics’ planned study. “We’re trying to approach this very much like we would any other medication,” he notes.
Diamond’s Phase II trial design
The Phase II trial’s primary objective is to establish the safety and tolerability of low-dose psilocybin selected in a previous Phase I study, McDonnell says. The planned Phase II trial will also measure the General Anxiety Disorder-7 (GAD-7) scale, which is a patient assessment of anxiety disorder symptoms, McDonnell says. In addition, the study will include other scales of anxiety and depression, which commonly occur alongside generalized anxiety disorder, he adds.
On December 7, Diamond Therapeutics reported that a 56-subject Phase I trial had established a safe and tolerable non-hallucinogenic psilocybin dose. McDonnell says there were no reported serious adverse events, and the most common reported side effect was drowsiness.
The main safety concern in the Phase II trial, though unlikely, is the worsening of anxiety symptoms, McDonnell notes. As a safety mechanism, the Phase II trial design allows for patients to take rescue doses of benzodiazepines—a class of anti-anxiety medications—if needed, he explains.
Generalized anxiety disorder, also referred to as GAD, is defined as severe anxiety that interferes with daily activities for at least six months. Approximately 6.8 million people in the US experience generalized anxiety disorder, including nearly twice as many women as men.
Rise in clinical trials for psilocybin
Overall, new clinical research and shifting regulatory perspectives have led to a recent surge in clinical trials testing psychedelics for psychiatric disorders. The sharp uptick in new trial activity is particularly clear for psilocybin.
According to GlobalData’s Clinical Trials Database, studies testing psilocybin account for 8.76% of all drug trials planned for psychiatric disorders in 2023. Meanwhile, just five years earlier, psilocybin trials accounted for less than 1% of all new trial initiations in the psychiatric disorder space. GlobalData is the parent company of Clinical Trials Arena.
Nevertheless, the recent growth of psychedelic trials is not without its challenges. In many cases, rising expectations for psychedelics can sometimes pose a challenge for clinical trial sponsors as they work to recruit patients and organize new trials. But given the high unmet need for medications to treat anxiety and other psychiatric disorders, the hope for new treatments remains high.
