Less than a month after reports of takeover talks between AbbVie and Gilgamesh Pharma first emerged, the pair have gone public with details of a $1.2 billion deal – but it is not an acquisition.
It turns out that AbbVie is only interested in buying Gilgamesh’s lead drug programme, a psychedelic candidate for major depressive disorder (MDD) – called bretisilocin (GM-2505) – that recently hit the mark in a phase 2a trial.
AbbVie is taking full control of the drug, described as a short-acting serotonin 5-HT2A receptor agonist and 5-HT releaser, for an undisclosed upfront payment and development milestones. Meanwhile, Gilgamesh is spinning out a new company with the same name that will take forward its remaining R&D programmes.
Those include an oral glutamate NMDA receptor antagonist, blixeprodil (GM-1020), which is also in mid-stage clinical testing for depression. The pipeline also includes a cardio-safe ibogaine analogue (GM-3009) for post-traumatic stress disorder (PTSD) and other indications, including opioid use disorder, an M1/M4 agonist programme in preclinical development for schizophrenia
AbbVie and Gilgamesh have been partnering since May 2024 on therapies for psychiatric disorders based on ‘neuroplastogens’, small-molecule drugs that can exert effects on neuronal structure and function that are designed to provide efficacy without the side effects associated with current psychiatric medicines, and those are also staying with the new company.
In May, Gilgamesh reported encouraging results with bretisilocin in a 40-patient study involving patients with moderate to severe MDD, including a 21.6-point reduction in the MADRS depression scale after two weeks, versus a 9.6-point reduction with a low-dose psychoactive comparator.
A rapid antidepressant effect was seen with Gilgamesh’s drug, an 18.5-point reduction from baseline in MADRS after just 24 hours.
That speed of onset has been held up as the main benefit for psychedelic medicines compared to other approaches to MDD, which often rely on sequentially trying different therapies that can take weeks to confer a benefit – if they are effective at all.
Nearly 300 million people are living worldwide with depression, and it is estimated that a third of them have symptoms that do not improve after first- and second-line treatment with conventional antidepressant drugs like SSRIs.
The benefit on MADRS at 24 hours is around the same magnitude as other psychedelics in development for MDD, including Beckley Psytech’s BPL-003, and greater than was seen in trials of Johnson & Johnson’s Spravato (esketamine), which is already approved for treatment-resistant depression and MDDD with suicidal thinking.
One potential advantage of Gilgamesh’s drug is a short duration of action compared to other psychedelics, limiting the risk of side effects.
The acquisition comes 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.
“The field of psychiatry represents one of the most challenging areas in medicine, with a significant need for innovative solutions,” said Roopal Thakkar, AbbVie’s chief scientific officer.
“This acquisition underscores our commitment to broadening and enhancing psychiatric care by investing in novel treatment approaches with the potential to reach patients for whom other treatments have been ineffective,” he added. “We look forward to advancing bretisilocin to late-stage clinical development.”
