Compass Pathways announces durable improvement in symptoms through 12 weeks in open-label phase 2 study of COMP360 psilocybin in post-traumatic stress disorder

• Study met primary safety endpoint; administration was well tolerated, with no serious adverse events observed
• Early and clinically meaningful improvement from baseline in mean CAPS-5 total score (29.5 point reduction at week 12), with change from baseline in mean SDS total score (14.4 point reduction at week 12)
• 81.8% response (reduction of ≥ 15 points in CAPS-5 score), 63.6% remission (total CAPS-5 ≤ 20) rates at week 4 with 77.3% response and 54.5% remission at week 12
• Measures of symptom scores relative to baseline improved following a single 25mg dose administered with psychological support (n=22)

Compass Pathways plc (Nasdaq: CMPS) ("Compass"), a biotechnology company dedicated to accelerating access to evidence-based innovation in mental health, today announced top-line results from an open-label phase 2 study evaluating the safety and tolerability of investigational COMP360 psilocybin treatment in 22 patients with post-traumatic stress disorder (PTSD). The study met its primary safety endpoint and available secondary efficacy endpoints. Study observations included meaningful and sustained symptom improvement from baseline in mean CAPS-5 total score, a measure of disease severity, and in Sheehan Disability Scale (SDS) score, a measure of functional impairment in daily life. Administration of COMP360 was well-tolerated, with a safety profile consistent with previous studies.

"These results, with early and lasting improvement in symptoms following a single administration of COMP360, are highly encouraging," said Dr. Guy Goodwin, Chief Medical Officer of Compass Pathways. "These observations, even with a small, open-label study, suggest that COMP360 could provide a clinically meaningful benefit and substantially improve patient daily function and quality of life. The well tolerated safety profile for COMP360 in patients with PTSD, with no serious adverse events observed, advance our understanding of potential applications of COMP360. We look forward to submitting the full results of this study for publication and potential presentation at an upcoming medical conference."

Key findings

• Administration was well tolerated, with no serious adverse events observed. There were no treatment-emergent serious adverse events. Treatment-emergent adverse events included headache (n=11 or 50.0%), nausea (n=8 or 36.4%), crying (n=6 or 27.3%), and fatigue (n=6 or 27.3%). There were two adverse events of suicidal ideation that resolved during the study. The first was a moderate and transient event which resolved on administration day in a patient who went on to be a responder, and it was deemed to be related to study drug. The second event was mild and occurred at week 7 in a non-responder, resolved during the study, and was deemed to be possibly related to study drug. Both participants had previous history of suicidality as measured by the Columbia-Suicide Severity Rating Scale.
  
  
• Durable improvement in symptoms from baseline observed following a single administration. Improvement in mean CAPS-5 total score from a baseline of 47.5 was observed (29.9 point reduction at week 4 and 29.5 point reduction at week 12).
  
  
• Improvement over time in Sheehan Disability Scale (SDS) measure of functional impairment over 12 weeks. From a mean SDS total score of 22.7 at baseline, there was a 11.7 point reduction at week 4 and a 14.4 point reduction at week 12.
  
  
• High and sustained rates of response and remission relative to baseline, with early onset of symptom improvement. Response, as defined by patients experiencing a ≥ 15-point improvement on CAPS-5 score, was 81.8% at week 4 and 77.3% at week 12. Remission, as defined by CAPS-5 total score of ≤ 20, was 63.6% at week 4 and 54.5% at week 12.
  
  
• No patients withdrew from the study and no patients returned to antidepressant medication treatment during the trial.
  

"PTSD is commonly underdiagnosed and even when recognized it is often left untreated. There have been no new medicines approved for the treatment of PTSD in over two decades, and effective treatment options are limited. It's promising to see positive signals from this study of investigational COMP360 psilocybin treatment in people with PTSD," said Dr. James Rucker, principal investigator, consultant psychiatrist, and lead for The Psychoactive Trials Group at King's College London.

"These promising results give us confidence to consider further robust evidence generation in the treatment of patients with PTSD," said Kabir Nath, CEO of Compass Pathways. "We are pleased to see the strong signal in PTSD, which, along with our prior data in treatment-resistant depression, lead us to believe that COMP360 has the potential to become an important treatment option for patients across a broad set of mental health conditions."

The open-label, multi-center, phase 2 safety study evaluated investigational COMP360 psilocybin treatment in 22 patients with PTSD resulting from trauma in adulthood. Participants received a single 25mg dose along with psychological support. Psychological support was provided by a licensed medical professional to ensure patient safety, which consisted of preparing participants for the treatment session, observing and being present with patients during the session and supporting them after the session. Primary endpoint was safety at week 12; available secondary endpoints were change in CAPS-5 from baseline and change in SDS total score from baseline.

The mean baseline severity of symptoms was a baseline of 47.5 (minimum of 25; maximum of 64) CAPS-5 total score, which is considered severe. The CAPS-5 assessment involves a structured interview that provides a PTSD diagnosis and measures symptom severity. The average age of participants at the time of screening was 39 and patients diagnosed with complex PTSD were excluded from study eligibility. The study was conducted at The Institute of Psychiatry, Psychology and Neuroscience at King's College London, Icahn School of Medicine at Mount Sinai in New York and Sunstone Therapies in Rockville, Maryland.

Compass previously announced 24-hour safety data from the study, which indicated that COMP360 was well-tolerated, with no treatment emergent serious adverse events.

About COMP360 in PTSD

COMP360 is a synthetic form of psilocybin under investigation as a treatment for certain difficult-to-treat mental health conditions when administered with psychological support. The psilocybin molecule has been shown to bind to specific receptors in the brain, including the serotonin 5-HT2A receptor ¹ . This receptor can mediate new patterns of functional connectivity across the brain, as well as cellular changes leading to neuroplasticity ^2,3 . Preclinical models related to the processing of trauma suggest a potential role for targeting the 5-HT2A receptor in the treatment of PTSD ⁴ .

¹ Halberstadt, AL et al., Journal of Psychopharmacology. 2011 Nov;25(11):1548-61.

² Petri, G et al., Journal of the Royal Society Interface. 2014 Dec 6;11(101):20140873.

³ Ly, C et al., Cell Reports. 2018 Jun 12; 23(11): 3170–3182.

⁴ Catlow, BJ et al., Experimental Brain Research. 2013 Aug;228(4):481-91.

About Compass Pathways

Compass Pathways plc (Nasdaq: CMPS) is a biotechnology company dedicated to accelerating patient access to evidence-based innovation in mental health. Our focus is on improving the lives of those who are living with mental health challenges and who are not helped by current treatments. We are pioneering the development of a new model of psilocybin treatment, in which our proprietary formulation of synthetic psilocybin, COMP360, is administered in conjunction with psychological support. COMP360 has Breakthrough Therapy designation from the U.S. Food and Drug Administration (FDA) and has received Innovative Licensing and Access Pathway (ILAP) designation in the UK for treatment-resistant depression (TRD).

We have commenced a phase 3 clinical program of COMP360 psilocybin treatment in TRD, the largest randomized, controlled, double-blind psilocybin treatment clinical program ever conducted. Previously, we completed a phase 2b study with top line data showing a statistically significant (p

Compass is headquartered in London, UK, with offices in New York and San Francisco in the United States. Our vision is a world of mental wellbeing. www.compasspathways.com

Forward-looking statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. In some cases, forward-looking statements can be identified by terminology such as "may", "will", "could", "would", "expect", "intend", "plan", "anticipate", "believe", "potential" and "continue" and "ongoing," or the negative of these terms or other comparable terminology, although not all forward-looking statements contain these words. Forward-looking statements include express or implied statements relating to, among other things, the safety or efficacy of investigational COMP360 psilocybin treatment as a treatment for TRD, PTSD or anorexia nervosa; our expectations regarding the full results for this phase 2 trial in PTSD; the potential for the pivotal phase 3 program in TRD, future pivotal trials in PTSD, or other trials to support regulatory filings and approvals; our ability to continue to advance its research, obtain regulatory approval or develop plans to bring COMP360 psilocybin treatment to patients, and our expectations regarding the benefits of our investigational COMP360 psilocybin treatment. The forward-looking statements in this press release are neither promises nor guarantees, and you should not place undue reliance on these forward-looking statements because they involve known and unknown risks, uncertainties, and other factors, many of which are beyond our control and which could cause actual results, levels of activity, performance or achievements to differ materially from those expressed or implied by these forward-looking statements.

These risks, uncertainties, and other factors include, among others: our expectations based on the top-line data from this phase 2 trial may change as full efficacy results and more patient data becomes available; full results from this phase 2 study in post-traumatic stress disorder or results from future studies may not be consistent with the top-line results to date; clinical development is lengthy and outcomes are uncertain, and therefore our clinical trials may be delayed or terminated; the results of early-stage clinical trials of our investigational COMP360 psilocybin treatment may not be predictive of the results of later stage clinical trials; our efforts to obtain marketing approval from the applicable regulatory authorities in any jurisdiction for COMP360 or any of future product candidates may be unsuccessful; and our efforts to obtain coverage and reimbursement for our investigational COMP360 psilocybin treatment, if approved, may be unsuccessful; and those risks and uncertainties described under the heading "Risk Factors" in our most recent annual report on Form 10-K or quarterly report on Form 10-Q and in other reports we have filed with the U.S. Securities and Exchange Commission ("SEC") , which are available on the SEC's website at www.sec . Except as required by law, we disclaim any intention or responsibility for updating or revising any forward-looking statements contained in this press release in the event of new information, future developments or otherwise. These forward-looking statements are based on our current expectations and speak only as of the date hereof.

Enquiries
Media: Amy Lawrence, amy@compasspathways.com, +44 7813 777 919
Investors: Stephen Schultz, stephen.schultz@compasspathways.com, +1 401 290 7324