Reunion’s psilocybin like drug shows promise for postpartum depression, moves to Phase 3

Reunion Neuroscience’s experimental psychedelic drug RE104 significantly reduced symptoms of postpartum depression (PPD) in a mid-stage trial, paving the way for a pivotal Phase 3 study.

Why it matters: PPD affects nearly 500,000 U.S. women annually, yet treatments are limited and often slow acting. If approved, RE104 could provide faster symptom improvements within 1 week, a more effective option for maternal mental health care.

Backstory:

• The Phase 2 study enrolled 84 women with moderate to severe PPD.

• A single 30 mg injection of RE104 led to a 23-point drop in depression scores after one week, versus 17.2 points in the control group.

• 71% of patients in the treatment arm achieved remission by day 7, compared to 41% in the control.

• The drug was well tolerated, with no serious safety concerns reported.

• The company argues its shorter effect time (under 4 hours) gives it an edge over traditional psilocybin therapies, which can last 6 to 8 hours.

Big picture: RE104 could reshape the PPD treatment landscape, which currently relies on Sage Therapeutics’ drugs Zurzuvae and Zulresso; both of which are facing commercial hurdles. A safe, effective, and faster-acting therapy would fill a major unmet need in maternal health.

Zoom out: Psychedelics are reshaping mental health treatment. RE104 could offer a more practical alternative to longer-acting agents like Compass Pathways’ COMP360—and build on the momentum set by Johnson & Johnson’s Spravato, an FDA-approved ketamine-based nasal spray that helped normalize clinical use of psychedelics in depression.