Another milestone achieved in major depressive disorder trial 

Cybin, a clinical-stage biopharmaceutical company developing psychedelic-based treatment options for mental health, has completed dosing in Cohort 5 of a Phase II trial evaluating CYB003, an investigational proprietary deuterated analog of psilocybin for the potential treatment of major depressive disorder (MDD).  

The dosing was completed with no serious adverse events or other adverse events that may preclude continued dosing. The completed Cohorts 4 and 5 evaluated two 12mg doses of CYB003, and recruitment is underway to commence dosing for Cohort 6, the final cohort in the Phase II portion of the study. 

“The completion of CYB003 dosing in Cohort 5 represents a significant milestone in the progression of our Phase II study, taking us one step closer towards establishing a therapeutically efficacious dose and advancing CYB003 towards pivotal studies with the goal of bringing CYB003 as a differentiated and rapid-acting therapeutic option for people with major depressive disorder,” said Doug Drysdale, Chief Executive Officer of Cybin. “We are proud of the speed with which we have advanced our clinical-stage programmes and remain on track to deliver topline efficacy data from this Phase II study later this year and submit data to the FDA in preparation for a potential pivotal study of CYB003.” 

To date, CYB003 has demonstrated a favourable safety and tolerability profile with no serious adverse events reported at the doses evaluated (1mg, 3mg, 8mg, 10mg, and 12 mg). Interim findings from the Phase I/IIa study have also demonstrated positive observations, showing that CYB003 dosing led to a rapid and robust psychedelic response in participants at low doses, while maintaining a safe and well-tolerated therapeutic profile. 

Upcoming milestones for the CYB003 program 

  • Completion of CYB003 dosing in MDD cohorts expected in Q3 2023 
  • Topline efficacy data readout from CYB003 Phase II clinical trial expected in Q3/Q4 2023 
  • US Food and Drug Administration (FDA) submission of CYB003 Phase I/IIa data for pivotal studies expected following topline efficacy data readout 

About the Phase I/IIa CYB003 trial 

The Phase I/IIa trial is a randomised, double-blind, placebo-controlled study evaluating CYB003 in participants with moderate to severe MDD and in healthy volunteers.  

Per a protocol amendment that was announced on 28 February 2023, the study introduced healthy volunteers for the lower (sub-therapeutic) dose cohorts and added a bioequivalence and food effect cohort to facilitate the transition to pivotal studies. Healthy volunteers receive two administrations (placebo/active and active/active) one week apart, and measures of psychedelic effect are assessed after each dose.  

Participants with MDD receive two administrations (placebo/active and active/active) three weeks apart and response/remission are assessed three weeks after each dose. MDD participants in the trial that are currently being treated with antidepressants will be allowed to remain on their antidepressant medication. 

The study will evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics, and psychedelic effect of ascending oral doses of CYB003. In participants with MDD, the trial will also assess rapid onset of antidepressant effect on the day of dosing, using the Montgomery-Asberg Depression Rating Scale and evaluate the incremental benefit of a second dose of CYB003 when administered in week three. An optional period of assessment will help determine the durability of treatment effect out to 12 weeks.  

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