AbbVie has agreed to acquire Gilgamesh Pharmaceuticals’ lead clinical candidate, bretisilocin (GM-2505), a psychedelic compound in Phase II development for major depressive disorder (MDD). The deal is valued at up to $1.2 billion, including upfront payment and milestones. Bretisilocin is a 5-HT2A receptor agonist and 5-HT releaser designed to provide therapeutic benefits with a shorter psychoactive duration compared to traditional psychedelics. Recent Phase IIa data showed a significant reduction in depression severity with favorable safety. AbbVie plans to advance bretisilocin into late-stage clinical development while Gilgamesh will spin out a new entity to pursue other programs. This acquisition signals AbbVie's expanding commitment to innovative psychiatric therapies.