Is AbbVie planning an epic Gilgamesh takeover?

AbbVie could be heading for its second acquisition in the space of a month, with reports emerging of late-stage negotiations with Gilgamesh Pharmaceuticals, a central nervous system (CNS) drug developer.

According to a Bloomberg report, citing people familiar with the matter, AbbVie is considering a bid of around $1 billion for New York-based Gilgamesh, whose lead programme is a serotonin-directed drug for major depressive disorder (MDD).

If confirmed, the deal would come just a few weeks after AbbVie agreed to buy autoimmune disease therapy specialist Capstan Therapeutics for up to $2.1 billion, and a few months after it completed a $200 million-plus takeover of Nimble Therapeutics and its peptide drug for psoriasis. Last year, it also bolstered its presence in the CNS sector by acquiring Alzheimer's disease drug developer Aliada Therapeutics for $1.4 billion.

AbbVie already has a working relationship with Gilgamesh, in the form of an R&D collaboration and opt-in licensing agreement for 'next-generation' therapies for psychiatric disorders that was signed in May 2024 with an upfront fee of $64 million.

The alliance, which includes another $1.95 billion in potential milestones, is focusing on 'neuroplastogens', small-molecule drugs – often with their roots in psychedelic compounds – that can exert effects on neuronal structure and function that are designed to provide efficacy without the side effects associated with current psychiatric medicines.

The aim is to ape the effects of psychedelics like ketamine and psilocybin whilst avoiding their psychoactive effects, like hallucinations, which mean they have to be administered in carefully controlled settings.

Since that agreement was signed, Gilgamesh has reported encouraging results with GM-2505, a serotonin 5-HT2A receptor agonist and 5-HT releaser in a phase 2a trial involving patients with moderate-to-severe MDD.

In the 40-subject study, patients were given either an intravenous dose of GM-2505 or a low-dose psychoactive comparator, achieving an 18.5-point reduction from baseline in the MADRS depression scale within 24 hours of the first dose.

A second IV administration was given two weeks later, after which investigators recorded a 28-point change in baseline with 94% of patients deemed to be in remission from MDD.

The results, released in May, prompted Gilgamesh chief executive Jonathan Sporn to speculate that GM-2505 could be a "groundbreaking therapy" for MDD that fits into the company's target of a simple, two-hour model for in-clinic treatment pioneered by Johnson & Johnson's Spravato (esketamine).

Spravato was first approved for treatment-resistant depression in 2019 and had its label extended to include adults with MDD and suicidal ideation the following year. Since then, it has grown into a blockbuster product with sales topping $1 billion for the first time last year.