FDA points way forward for Compass Pathways' psilocybin in treatment-resistant depression

Compass Pathways has initiated a rolling New Drug Application (NDA) to the US FDA for COMP360 (synthetic psilocybin), seeking approval in patients with treatment-resistant depression (TRD). The FDA granted the rolling review request and simultaneously selected COMP360 for its Commissioner's National Priority Voucher (CNPV) pilot program, a designation that carries enhanced agency communications and a shortened review window of one to two months following formal NDA filing.

Compass is aiming to be the first company to receive approval for a classic psychedelic compound in the United States. The application is supported by data from two Phase III randomized controlled trials, which the company said enrolled more than 1,000 participants with TRD. Compass has not disclosed a projected PDUFA date, though the CNPV designation is expected to compress the standard review timeline once the rolling submission is complete.

TRD is defined clinically as an inadequate response to two or more adequate courses of approved antidepressant therapy. An estimated four million patients in the United States meet that threshold, according to data the company cited from the 2026 Annual Meeting of the Anxiety and Depression Association of America. The condition carries substantially higher rates of functional impairment, comorbidity, and suicide risk than non-treatment-resistant major depressive disorder.

The clinical data package Compass presented to the FDA draws on two large Phase III trials, which the company described as producing statistically significant and clinically meaningful results. In its announcement, Compass said COMP360 demonstrated effects within one day of administration in responding patients, with durability extending to at least six months following one or two doses. The company reported that a majority of treatment-emergent adverse events were mild or moderate in severity and that most resolved within 24 hours. The underlying Phase IIb randomized controlled trial, published in Neuroscience Applied, provided the mid-stage evidence that preceded the Phase III program, with a long-term observational follow-up subsequently published in the same journal.

COMP360 holds Breakthrough Therapy designation from the US FDA and Innovative Licensing and Access Pathway designation in the United Kingdom, both for TRD. The Breakthrough designation, granted on the basis of early clinical evidence, provides more intensive FDA guidance during development and is distinct from the CNPV, which operates as a process-level accelerant rather than an evidentiary standard adjustment. Compass was explicit on this point, noting that CNPV selection does not alter the safety and efficacy requirements for approval.

The CNPV program is a recent FDA initiative, and COMP360 joins only a small number of compounds selected under it. Hernexeos (zongertinib), a lung cancer therapy, received the second approval under the program in 2026 following an NDA filed in January of that year, illustrating the compressed timelines the voucher can enable once a submission is complete.

The TRD pharmacotherapy landscape against which COMP360 would compete includes esketamine (Spravato), which received FDA approval in 2019 as an adjunctive treatment and in January 2025 as a monotherapy, and lumateperone (Caplyta), approved as an adjunctive agent in November 2025. Both require ongoing dosing. Esketamine, an NMDA receptor antagonist administered intranasally, carries a Risk Evaluation and Mitigation Strategy requiring in-clinic administration and a two-hour post-dose monitoring period, a logistical constraint that limits real-world access. Neuromodulation options including transcranial magnetic stimulation and electroconvulsive therapy are available but face their own access and tolerability barriers.

The mechanistic profile of psilocybin differs from all currently approved TRD pharmacotherapies. Where approved agents act on monoaminergic or glutamatergic pathways, psilocybin is a serotonin 5-HT2A receptor agonist hypothesized to produce neuroplastic changes that may underlie durable antidepressant effects from a limited number of administrations. This potential for sustained benefit from a short treatment course, rather than chronic dosing, is the central clinical hypothesis distinguishing the compound from the existing armamentarium, though the regulatory review will assess the strength of evidence for that claim.

The broader field of psychedelic medicine has faced regulatory headwinds. In 2024, the FDA declined to approve an MDMA-assisted therapy from Lykos Therapeutics for post-traumatic stress disorder, citing concerns about trial design and the difficulty of blinding in psychedelic studies — methodological challenges that are not unique to MDMA and that Compass has sought to address through what it describes as large, well-controlled trial designs meeting regulatory standards. The outcome of the COMP360 NDA review will carry implications for how the FDA approaches this class more broadly.

Compass said it is advancing commercial preparations in parallel with the rolling submission, and the CNPV is intended to reduce the interval between completed filing and a regulatory decision. The company has not disclosed the precise timeline for completing the rolling NDA submission, meaning the eventual review clock has not yet formally started. Whether the two Phase III datasets, once fully submitted and reviewed, satisfy the FDA's standards for a novel mechanism in a population with significant unmet need will determine whether COMP360 becomes the first approved classic psychedelic therapy in the United States.

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