eunion Neuroscience is preparing to move its experimental psychedelic therapy into late-stage testing following encouraging mid-stage trial results in women with postpartum depression (PPD).
The company announced Monday that its investigational drug, RE104 — a psilocybin-like compound — produced rapid and meaningful improvements in women with moderate-to-severe PPD. Some participants experienced benefits within just 24 hours of treatment.
“We are encouraged by the results from our RECONNECT Phase II trial, which provide strong clinical validation for RE104 as a well-tolerated and effective treatment for PPD offering rapid relief with minimal interruption to daily activities,” said Dr. Mark Pollack, Reunion’s chief medical officer.
The RECONNECT study, supported by a $103 million Series A financing round last year, enrolled 84 women between ages 21 and 45. Participants received either a single 30-milligram subcutaneous dose of RE104 or a 1.5-milligram dose as an active control.
Results showed that patients on the higher dose achieved clinically significant reductions in depression scores as early as day one, with effects sustained through the 28-day follow-up. On day seven, the high-dose group recorded a 23-point reduction on the Montgomery-Åsberg Depression Rating Scale (MADRS), compared with a 17.2-point reduction for the control group — meeting the trial’s primary endpoint.
At the one-week mark, 77.1% of patients in the high-dose group achieved at least a 50% improvement in MADRS scores, while 71.4% reached remission. By contrast, 61.6% and 41% of patients in the control group met those respective benchmarks.
The treatment was generally well-tolerated. Nausea (43.9%) and headache (34.1%) were the most common side effects, mostly occurring on the day of dosing. Importantly, no serious adverse events — such as suicidal ideation — were reported. Within four hours of administration, 92.7% of patients were ready for discharge, setting RE104 apart from traditional psychedelics like psilocybin or LSD, which often require longer supervision due to extended psychoactive effects.
A separate lactation study showed that less than 0.1% of the drug’s metabolites were present in breast milk, a level far below thresholds considered harmful for infants.
Reunion plans to launch a pivotal Phase III trial of RE104 for PPD in 2026. Ahead of that, the company will begin the Phase II REKINDLE study later this year, testing RE104 in patients with adjustment disorders linked to cancer and other medical conditions.
Additionally, Reunion is preparing another Phase II study for RE104 in a major yet undisclosed mental health condition, expected to start in early 2026.
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