A group of scientists have reported findings that provide a foundation for the structure-based design of safe and effective non-hallucinogenic, rapid-acting antidepressants.
Psychedelic medicines are showing promising results for a number of indications such as depression, anxiety and PTSD. However, many drug development companies are searching for psychedelic compounds without the trip – as this aspect can make it difficult to deliver care at scale.
A team of scientists have now reported for the first time a structure-based strategy to design novel rapid-acting antidepressant compounds.
The team was led by Dr Wang Sheng at the Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology of the Chinese Academy of Sciences, and Dr Cheng Jianjun at the iHuman Institute, ShanghaiTech University.
Extended binding pocket binding
Psilocybin – the psychedelic compound found in a number of different mushrooms – is converted in the liver to pharmacologically active psilocin, which then acts on serotonin 2A receptors (5-HT2AR) in the brain.
For the study, the team produced six new crystal structures of 5-HT2AR that bound to compounds including psilocin, LSD, serotonin and non-hallucinogenic psychedelic analogues.
The team discovered that psilocin displayed an unexpected binding mode known as the “extended binding pocket” (EBP) mode, which is regulated by lipids. They also found that compounds that occupied more EBP than “orthosteric binding pocket” (OBP) – the usual site for receptor binding – were associated with anti-depressive activity in test animals without triggering hallucinations.
The scientists then designed several new psychedelic analogues they thought would favour EBP binding over OBP binding.
After repeating behavioural tests on mice receiving the compounds, the team found that two compounds – IHCH-7079 and IHCH-7806 – did not trigger “head twitch behaviour”, which is commonly seen as indicative of hallucinations.
Instead, the mice displayed standard behavioural measures, which the authors suggest means that the compounds were effective antidepressants.
Science explains that: “The structures reveal ligand-receptor interactions that cause a bias toward arrestin recruitment. Based on these insights, the authors designed arrestin-biased ligands that displayed antidepressant-like activity in mice without hallucination effects.
“Arrestin recruitment alone is insufficient for antidepressant effects, but the low G-protein signaling of the arrestin-biased ligands appears to allow antidepressant effects without causing hallucination.”
The authors state: “Serotonin and psilocin display a second binding mode in addition to the canonical mode, which enabled the design of the psychedelic IHCH-7113 (a substructure of antipsychotic lumateperone) and several 5-HT2AR β-arrestin–biased agonists that displayed antidepressant-like activity in mice but without hallucinogenic effects.
“The 5-HT2AR complex structures presented herein and the resulting insights provide a solid foundation for the structure-based design of safe and effective non-hallucinogenic psychedelic analogues with therapeutic effects.”
The team pointed out that the compounds reported in the study are not approved drugs, and further preclinical and clinical studies are needed to verify their safety and antidepressant effects in humans.
Psilocybin analogue shows positive results in Phase 2 depression study
Cybin has announced positive Phase 2 topline safety and efficacy data for its proprietary deuterated psilocybin analogue – CYB003 – for the treatment of major depressive disorder (MDD).
Results from Cybin’s study have shown that 79% of patients were in remission from depression at six weeks after receiving two doses of CYB003.
CYB003 demonstrated a large improvement in symptoms after one dose and a total of 79% of patients were responsive to the treatment. The compound also demonstrated an excellent safety profile in doses tested, with all reported adverse events mild to moderate and self–limiting.
Additionally, Cybin has stated that the magnitude of improvement was superior compared to approved antidepressants and recently reported data with other psychedelics, stating that the effects translate into an unprecedented effect size.
The company has said that the results compare favorably to pooled data from 232 industry studies of current standard-of-care antidepressants, SSRIs, submitted to the FDA.
The announcement follows Phase 2 interim results in early November 2023, which demonstrated that CYB003 saw a “rapid, robust and statistically significant reduction in symptoms of depression three weeks following a single 12mg dose compared to placebo”.
Cybin CEO, Doug Drysdale, stated: “We are delighted to share that CYB003 achieved the primary efficacy endpoint in this study and showed rapid and statistically significant improvements in depression symptoms after a single dose, with a clear incremental benefit of a second dose, resulting in four out of five patients in remission from their depression at six weeks.
“This is an impressive finding and follows on from the unprecedented interim results we announced earlier this month.”
Drysdale emphasised that the strength of the data will support CYB003 into Phase 3 of the study.
Cybin CMO, Amir Inamdar, added: “The significant reduction in depression symptoms observed in our Phase 2 study is highly gratifying.
“At the three-week primary efficacy endpoint, a single 12mg dose of CYB003 showed a rapid, robust, and highly statistically significant improvement in depression symptoms compared to placebo, with a -14.08 point difference in change from baseline in MADRS.
“This translated into a very large effect size. Similar significant and robust effects were also seen with a single 16mg dose, which resulted in an improvement in symptoms of depression as measured using the MADRS total score by about 13 points versus placebo.
“These effects were evident on day one with the 16mg dose and were also highly statistically significant. When data from 12mg and 16mg are pooled, these robust effects are maintained. Further, with two doses, response and remission rates in excess of 75% were observed with CYB003 (12mg).
“With these findings in hand, we are encouraged by the potential of CYB003 to help those with MDD and look forward to progressing to a multinational, multisite Phase 3 study early next year.”
Cybin is planning on submitting topline data to the FDA with an aim to hold a Phase 2 meeting in Q1 of 2024, with further 12-week durability data from Phase 2 CYB003 expected in Q1, and recruitment for the Phase 3 study anticipated to begin by the end of Q1 2024.
Clerkenwell Health calls for volunteers to support groundbreaking psychedelic research
Mental health research provider Clerkenwell Health is calling for volunteers to join its groundbreaking clinical trials that will research whether psychedelics can provide effective treatments for complex mental health conditions.
Clerkenwell is seeking a diverse group of volunteers from across the UK between 18 and 65 years old to take part in the trials if they suffer from a relevant condition.
The trials, which will be conducted at Clerkenwell Health’s purpose-built facility near Harley Street in London, are being run in partnership with a number of world-leading drug developers to test whether psychedelic drugs – often combined with talking therapy – can offer a new approach to treating a variety of mental health illnesses.
Clerkenwell Health is seeking volunteers for trials that look to find cures for a range of conditions, including PTSD, depression, alcohol use disorder and anorexia.
Many of the conditions have few successful treatment options and Clerkenwell’s innovative methods of combining psychedelics with therapy aim to to treat these problems more holistically, providing long-term quality of life for patients.
Chief Scientific Officer at Clerkenwell Health, Dr Henry Fisher, said: “With the current system for treating mental health disorders simply not working, we’re calling for patients to help identify the next wave of treatments.
“These have the potential to be groundbreaking for the millions of people across the UK who are affected by poor mental health.
“The status quo for mental health treatment has not only resulted in patients experiencing debilitating side-effects, huge waiting lists and high relapse rates, but is costly, complicated and broadly ineffective.
“By participating in upcoming clinical trials, patients have an opportunity to make a valuable contribution to growing research which will support the development of the next generation treatments for mental health conditions.”
According to MIND, approximately 1 in 4 people in the UK will be affected by a mental health condition each year and with a significant rise in people contacting mental health services in recent years, there has never been a more desperate need to identify new and innovative treatments.
Given the challenges facing the country’s health service and with mental health challenges on the rise, the search for volunteers to test effective treatments has never been more pressing.
Clerkenwell has stated, in this regard, that it has gone national with its search for volunteers in an effort to deliver medical breakthroughs in mental health akin to the Polio clinical trials in the 20th Century.
Paper explores extended difficulties following psychedelic trips
A new paper has explored the extended difficulties experienced by some people following psychedelic drug use and discusses psychedelic harm reduction.
While multiple studies have shown that psychedelics can be safe when administered appropriately, some people experience difficulties following their use. These difficulties can last anywhere from a few days to years.
With a rise in clinical research surrounding these compounds, there is a drive to change drug policy and several places have already implemented progressive approaches to accessing these therapies such as decriminalisation or including them on authorised medical access schemes.
In light of these developments, it is vital to understand the potential risks associated with psychedelic use and what actions can be taken to reduce these risks.
The paper has been published in Plos One and authored by a team of leading psychedelic scientists from the Universities of Exeter, Greenwich and Queen Mary, University College London and Royal Holloway, New York University and the Perception Restoration Foundation.
Extended difficulties following psychedelic use
The team of researchers has gathered data on the context of use, nature and duration of these difficulties and explored risk factors and perceived causes that may contribute to these experiences.
The most common forms of extended difficulty that the team uncovered include symptoms such as anxiety/fear and existential struggle, as well as social disconnection, depersonalisation and derealisation.
“For approximately one-third of the participants, problems persisted for over a year, and for a sixth, they endured for more than three years,” the authors write.
The findings revealed that the length of time these experiences last following psychedelic use could be predicted by the participants’ knowledge of dose and drug type, and that the experiences were shorter if a participant had taken part in a guided psychedelic experience.
Additionally, the most common length of time such difficulties lasted was between one and three years. When asked about mental illness onset following the psychedelic experience, 18.8% said they had gone on to be diagnosed with a mental illness, while 76.8% said they had not.
The authors write: “Our findings support the results of Simonsson et al., who found that anxiety was the most common enduring difficulty, based on quantitative questionnaire data and Bouso et al’s study of the Global Ayahuasca Survey, in which ‘feeling nervous, anxious or on edge’ was the second most common adverse mental health effect. Our findings also suggest that a Sense of disconnection from others was within the top five most prevalent themes, as did the studies by Simonsson et al. and Bouso et al.
“Some extended adverse effects that were quite common in other studies weren’t so common in our data set–for example, feeling a harmful connection to the spirit world was reported by 14% of respondents to the Global Ayahuasca Survey but by less than 4% of our data set, which may suggest some forms of difficulty are particularly associated with certain psychedelic substances and/or their associated cultures.”
Reducing risk factors
The authors suggest a number of actions that could be taken to reduce these risks.
Highlighting that, as anxiety and fear are some of the most commonly reported difficulties, the authors suggest that all legal psychedelic experience providers give guidance on methods for “self-soothing and overcoming bouts of anxiety following the retreat, clinical trial or ceremony.”
Further suggestions include informing participants of potential harms and risks and advising participants that the integration process may take some time, and what practices can be done to help people cope with difficulties. The authors say these practices will be explored in an upcoming paper.
The team writes: “We envisage using the information in this study, and accompanying future papers that focus on social support and forms of coping used by those with enduring difficulties, to provide structured guidance and training to psychedelic retreats, therapists and clinical trial centers about the potential for adverse experiences, what the potential risk factors are and what can be done to help individuals who report such extended difficulties.”
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