AbbVie Inc. announced a definitive agreement to acquire Gilgamesh Pharmaceuticals Inc.'s lead investigational therapy, bretisilocin (GM-2505), in a deal valued at up to $1.2 billion. The drug, currently in Phase 2 clinical development, represents a potential breakthrough treatment for major depressive disorder (MDD) and underscores the pharmaceutical giant's commitment to advancing psychiatric care through novel therapeutic approaches.
Novel Mechanism Addresses Treatment Limitations
Bretisilocin is a short-acting psychedelic compound that targets the serotonin 5-HT2A receptor and acts as a 5-HT releaser. Unlike existing agents in the same class, which can trigger prolonged psychoactive experiences, bretisilocin has been designed to deliver rapid and durable antidepressant benefits while significantly reducing the duration of hallucinogenic effects.
The compound's unique profile addresses a critical challenge in psychedelic medicine: balancing therapeutic efficacy with patient tolerability and clinical practicality. Traditional psychedelic therapies often require extensive monitoring due to prolonged hallucinogenic effects, potentially limiting their widespread adoption in clinical settings.
Promising Phase 2a Results Drive Acquisition
Phase 2a trial results demonstrated bretisilocin's therapeutic potential. A single 10mg dose achieved a -21.6-point reduction in depressive symptoms on the Montgomery-Åsberg Depression Rating Scale (MADRS) by Day 14, compared with -12.1 points for a low-dose comparator. The therapy was well tolerated, with no serious adverse events reported during the study period.
These results represent a substantial improvement over the comparator group, suggesting bretisilocin could offer meaningful clinical benefits for patients with major depressive disorder. The rapid onset of action, combined with the durability of effects, positions the compound as a potentially transformative treatment option in a field where current therapies often require weeks to demonstrate efficacy.
Strategic Investment in Psychiatric Innovation
"The field of psychiatry represents one of the most challenging areas in medicine, with a significant need for innovative solutions," said Dr. Roopal Thakkar, AbbVie's executive vice president of research and development. "This acquisition underscores our commitment to broadening psychiatric care by investing in novel treatment approaches. We look forward to advancing bretisilocin to late-stage clinical development."
The acquisition builds on a 2024 partnership between AbbVie and Gilgamesh aimed at advancing next-generation psychiatric therapies. This strategic relationship provided AbbVie with insights into Gilgamesh's pipeline and development capabilities, ultimately leading to the current acquisition agreement.
Gilgamesh Restructuring Preserves Pipeline
As part of the transaction, Gilgamesh will spin off a new entity, Gilgamesh Pharma Inc., which will retain its employees and pipeline programs. The new company will continue developing other novel therapies for mental health and neurological disorders, including blixeprodil (GM-1020), an NMDA receptor antagonist, as well as a cardio-safe ibogaine analog and M1/M4 agonist programs.
Gilgamesh CEO Dr. Jonathan Sporn called AbbVie "the ideal partner to advance bretisilocin rapidly," noting that the acquisition allows Gilgamesh to continue developing other novel therapies while ensuring bretisilocin receives the resources necessary for late-stage development. The company's existing collaboration with AbbVie will also be transferred to the new entity.
Market Impact and Future Development
The deal represents one of the largest acquisitions in the psychedelic medicine space, signaling growing pharmaceutical industry confidence in psychedelic-based therapies for psychiatric conditions. AbbVie's investment provides validation for the broader field of psychedelic medicine and could accelerate development timelines for similar compounds.
The acquisition is subject to customary closing conditions, with AbbVie expected to advance bretisilocin through late-stage clinical development. The company's extensive resources and regulatory expertise position bretisilocin for potential rapid advancement through Phase 3 trials and toward potential regulatory approval.
