AbbVie and Gilgamesh Pharmaceuticals Inc. announced a definitive agreement under which AbbVie will acquire bretisilocin, Gilgamesh’s lead investigational candidate currently in clinical development for moderate-to-severe major depressive disorder (MDD).
Psychedelic compounds such as 5-HT2A receptor agonists have emerged as promising treatments for mental health disorders, offering rapid and durable antidepressant effects. However, existing agents are limited by prolonged psychoactive experiences.
Bretisilocin, a next-generation 5-HT2A receptor agonist and 5-HT releaser, is designed to overcome these challenges. It has shown the ability to deliver an extended therapeutic benefit with a shorter psychoactive duration compared to existing compounds.
Recently reported positive Phase 2a results in MDD demonstrated that a single 10 mg dose of bretisilocin led to a -21.6 point change in MADRS total score, compared to -12.1 with a low-dose comparator (p = 0.003), at Day 14. The treatment was well tolerated with no serious adverse events.
“Psychiatry remains one of medicine’s most challenging fields, with a strong need for innovation,” said Roopal Thakkar, M.D., EVP of R&D and CSO, AbbVie. “This acquisition reinforces our commitment to advancing novel treatment approaches for patients unresponsive to current therapies. We are eager to move bretisilocin into late-stage development.” “AbbVie’s leadership in neuroscience makes them the ideal partner to advance bretisilocin quickly while enabling us to pursue our broader mission of developing transformative therapies,” added Jonathan Sporn, M.D., CEO, Gilgamesh Pharmaceuticals.
Under the agreement, AbbVie will acquire the bretisilocin program for up to $1.2 billion, including upfront payments and milestones. Gilgamesh will also spin off a new entity—Gilgamesh Pharma Inc.—to continue developing its other programs, including blixeprodil (GM-1020), a cardio-safe ibogaine analog, M1/M4 agonists, and its ongoing collaboration with AbbVie.
The deal, subject to customary closing conditions, builds on the 2024 AbbVie-Gilgamesh collaboration and option-to-license agreement for next-generation psychiatric therapies, which will be transferred to Gilgamesh Pharma Inc. as part of the spin-out.