Reunion Neuroscience raises $103 million for a psychedelic to treat depression

Reunion Neuroscience, a start-up focused on mental health, has raised a $103 million series A round, co-led by MPM BioImpact and the Novo Nordisk Foundation’s investment arm Novo Holdings. The company’s lead asset, RE104, is a novel psychedelic that is being developed to treat adjustment disorder in cancer patients as well as postpartum depression.

RE104 is a prodrug of 4-OH-DiPT, which acts on the serotonin 2A receptor in a manner similar to that of psilocybin. It is thought to improve neuroplasticity and the formation of new neural pathways. But its exact mechanism of action, like that of psilocybin, is unknown. According to Greg Mayes, Reunion’s president and CEO, RE104 has a critical advantage over psilocybin: brevity. One session of psilocybin therapy takes about 6–8 hours of administration and monitoring, but one session of RE104 therapy should take half that time.

“That is significant for patients’ acceptance of the process,” as well as for physician time and office space, and coverage through insurance companies and third-party payers, says Mayes.

Mayes says that the company has received “extensive” intellectual property protection for RE104 lasting into 2042, giving the company more freedom for research and development. As for whether the therapy will be affordable for patients, he said that the biggest factor will be approval from the US Food and Drug Administration, which will determine how insurance will pay for the therapy.

The FDA has approved only two drugs to treat postpartum depression: zuranolone, an oral drug, and brexanolone, an intravenous drug that requires a stay in the hospital for 2½ days for monitoring. The FDA has not approved any drug to treat adjustment disorder in cancer patients.

Currently, Reunion’s postpartum depression program is taking the lead. The series A funding will be used to carry out a Phase 2 trial, which is expected to dose its first patient this quarter and finish in the first half of 2025. Mayes estimates that the drug could be approved in 2028 at the earliest, with the adjustment disorder program following behind.

Reunion filed a lawsuit against Mindset Pharma in March 2023, accusing that company of copying RE104 and trying to patent it. According to court records, the suit was dismissed in early January.