AbbVie will acquire Gilgamesh's bretisilocin (GM-2505) for up to $1.2B, bringing a serotonergic psychedelic for major depressive disorder into big pharma

Bretisilocin (GM-2505), a serotonergic psychedelic being developed for major depressive disorder (MDD), is the lead candidate Gilgamesh Pharmaceuticals is set to sell to AbbVie. The deal values the acquisition at up to $1.2B, including an upfront payment and development milestones. A key structural detail is that Gilgamesh plans to spin out “Gilgamesh Pharma Inc.” to keep its employees and other pipeline programs, while transferring the option-to-license arrangement connected to AbbVie. The news frames the transaction as a signal of big pharma interest in psychedelic development, and highlights potential implications for other psychedelic drug developers competing for investment and partnerships.