Pharma BD Deal Intelligence
AbbVie acquired Gilgamesh Pharmaceuticals' lead asset bretisilocin (GM-2505), a novel short-acting serotonin 5-HT2A receptor agonist and 5-HT releaser in Phase 2 development for moderate-to-severe major depressive disorder (MDD), for up to $1.2B (upfront plus development milestones). The deal was announced August 25, 2025 and completed October 17, 2025. As part of the transaction Gilgamesh spun off its remaining programs into a new independent entity, Gilgamesh Pharma Inc. Bretisilocin is designed for a shorter in-office dosing experience than classic psychedelics such as psilocybin, and the Phase 2a MDD study reported a statistically significant reduction in MADRS depression severity versus low-dose active comparator. The acquisition is AbbVie's first major move into psychedelic medicine, extending its neuropsychiatry pipeline beyond the assets gained in the Cerevel Therapeutics acquisition; AbbVie has stated it intends to accelerate bretisilocin into late-stage development.