Compass Pathways has reported another phase 3 win for its psilocybin therapy in treatment-resistant depression, sending the British biotech’s share price up 30% and teeing up talks about filing for approval.
London-based Compass had already reported a win for COMP360, a synthetic form of the magic mushroom extract psilocybin, in one phase 3 trial last year. The biotech’s share price dropped in the wake of the update, only to regain lost ground—and then some—in the following weeks and months. A second trial offered Compass a chance to maintain momentum by showing the effect of a second dose.
In the latest study, patients received two doses of COMP360 three weeks apart. At Week 6, Compass reported a statistically significant 3.8-point reduction in symptom severity measured by the Montgomery-Åsberg Depression Rating Scale (MADRS). The analysis compared 25 mg of COMP360 to a 1-mg control dose. Compass CEO Kabir Nath discussed the findings on a call with investors.
“The key takeaways are that COMP360 is safe to try and that if you respond, on average, you do so on day one,” Nath told investors on a call this morning.
“If you have a clinically meaningful reduction in MADRS, the treatment effect is durable,” Nath added.
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In a note to investors last week, TD Cowen analysts said a MADRS reduction of 4 to 5 points was their base-case scenario. Compass reported a 3.6-point, placebo-adjusted MADRS reduction at Week 6 in its first phase 3 trial. Participants only received a single dose of COMP360 in the primary endpoint analysis of the earlier study.
The analysts last week named a 30% remission rate as the other part of their base-case expectations for the second trial. Compass’ press release and data presentation this morning lack a remission rate. The only remission data cover patients in the first study who had a clinically meaningful MADRS reduction but had not remitted by Week 6. A total of 40% of those patients went into remission after receiving a second dose.
Compass also shared durability data from the first trial. Improvements seen at Week 6 persisted out to Week 26, although they trended in the wrong direction over the final four weeks. A total of 70% of patients in the COMP360 cohort received a second dose at Week 6.
Across the two trials, the biotech reported one suicidal behavior serious adverse event. The participant received the 1-mg control dose in the second phase 3 trial. The rate for suicidal ideation was less than 1% across the two trials. The chair of the independent data safety monitoring board said there is no evidence of a clinically meaningful imbalance between treatment arms in suicidality in either study.
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On the back of the latest data, Compass has asked for a meeting with the FDA to discuss a rolling approval submission that it aims to complete in the fourth quarter. Nath said the company has asked for—and expects to receive—an expedited review.
Analysts at Evercore expressed increased confidence in the drug’s prospects, writing in a Feb. 17 note that COMP360 “looks like an approvable drug,” citing durability data that exceeded their expectations heading into the trial.
Compass’ share price rose 31% to $7.60 in premarket trading Tuesday from a Friday closing price of $5.81.
