AbbVie Inc., advised by Covington & Burling LLP, has announced a blockbuster acquisition of Gilgamesh Pharmaceuticals’ lead psychedelic therapy candidate, bretisilocin, in a deal worth up to $1.2 billion. The agreement, unveiled Monday, positions AbbVie at the forefront of cutting-edge psychiatric care, targeting moderate-to-severe major depressive disorder.

Under the terms, AbbVie will purchase the bretisilocin program through an upfront payment and development milestones. Gilgamesh, represented by Ropes & Gray LLP, will simultaneously spin off a new company—Gilgamesh Pharma Inc.—to retain its workforce and continue development of other research programs.

Bretisilocin: A Next-Gen Psychedelic Therapy

Unlike traditional psychedelic compounds, bretisilocin is engineered to shorten the psychoactive experience while preserving its long-term therapeutic benefits. The compound has generated buzz in the psychiatric field as a potential breakthrough for patients who have found little relief in existing therapies.

Roopal Thakkar, AbbVie’s Executive Vice President of R&D and Chief Scientific Officer, emphasized the importance of the deal:

“Psychiatry remains one of the most complex fields in medicine, and patients urgently need innovative solutions. This acquisition reflects AbbVie’s dedication to expanding psychiatric treatment options with novel approaches.”

From Collaboration to Acquisition

The acquisition builds on a partnership established in 2024, when AbbVie and Gilgamesh entered into an option-to-license agreement to explore next-gen psychiatric therapies. That agreement will now transfer to the newly spun-off Gilgamesh Pharma, ensuring continuity in both research and collaboration.

Gilgamesh CEO Jonathan Sporn hailed the deal as transformative:

“AbbVie’s leadership in neuroscience makes them the ideal partner to accelerate bretisilocin’s development, while Gilgamesh can continue advancing its mission of delivering groundbreaking therapies for complex mental health and neurological conditions.”

Legal Advisors Behind the Deal

• AbbVie: Advised by Covington & Burling LLP, with partners Catherine Dargan and Kyle Rabe leading the team.

• Gilgamesh: Represented by Ropes & Gray LLP, with life sciences partner Hannah England and M&A partner Matt Byron steering the transaction.

This acquisition, blending pharmaceutical innovation with psychedelic science, underscores how far Big Pharma is willing to go in the race to conquer treatment-resistant depression—staking billions on a future where mental health care may look very different from today.