A drug has two clocks. One measures what happens in the brain. The other measures how long someone must sit in a treatment room. Gilgamesh Pharma built its business around the awkward relationship between them. A medicine might act quickly and still consume a patient’s day. An intriguing molecule might also be a thoroughly inconvenient product.
- AbbVie acquired bretisilocin after Gilgamesh spun out its other programs and employees.
- The independent company’s lead candidate, blixeprodil, is an investigational oral depression treatment.
- A $60 million financing in March 2026 funds the next chapter. Early clinical signals still need larger trials.
That helps explain an unusual ending. In October 2025, AbbVie completed the acquisition of Gilgamesh Pharmaceuticals and its lead program, bretisilocin. But the people and remaining programs had been placed in a new, independent company, Gilgamesh Pharma Inc. The research team could continue while a larger pharmaceutical company took responsibility for the acquired candidate.
01 / The exit with a sequel
Acquisition headlines advertised up to $1.2 billion. AbbVie’s annual filing supplies the less glamorous, more informative arithmetic: $906 million paid upfront, with up to $300 million in additional development milestones. Conditional payments are promises attached to conditions. They belong in a different mental drawer from cash already paid.
Acquisition of the predecessor after the spinout. Bars compare disclosed payment amounts, not company valuation.
The distinction matters because Gilgamesh has several financial stories. The predecessor raised $27 million in 2021 and $39 million in 2022. In March 2026, the independent spinout announced a $60 million Series A, led by Satori Neuro with Prime Movers Lab participating. A Series A following a Series B looks peculiar until you notice the change of company.
Its business model is familiar biotechnology economics: create proprietary drug candidates, generate evidence, and negotiate with pharmaceutical partners. Research agreements, licensing options and asset transactions can produce income before an approved medicine reaches a pharmacy. Patients are the intended beneficiaries; pharmaceutical companies are the commercial counterparties. There is no Gilgamesh subscription to buy.
02 / Make the molecule fit the appointment
Founded in 2019, Gilgamesh joined Y Combinator’s Summer 2020 batch. Its founders brought together psychiatry, medicinal chemistry and pharmacology. Jonathan Sporn leads the company; Andrew Kruegel is chief scientific officer. Dalibor Sames, Michael Cunningham and Jeffrey Witkin were also among its founders. The company’s starting proposition was to create new molecules with selected properties, rather than simply carry familiar psychedelic compounds into trials.
Bretisilocin, formerly GM-2505 and now ABBV-2505, illustrates that approach. It is a short-acting serotonin 5-HT2A receptor agonist and serotonin releaser, developed for major depressive disorder. Gilgamesh describes a two-hour treatment window. Duration becomes part of the product brief: how much benefit might a clinician deliver within a manageable appointment?
In May 2025, Gilgamesh reported positive Phase 2a results from 40 patients. The study compared a 10 mg intravenous dose with a 1 mg psychoactive comparator before a second dose on day 15. The company reported a statistically significant depression-score advantage at day 14. Those results preceded AbbVie’s acquisition; they did not turn an investigational drug into an approved treatment.
“Our mission is to fundamentally reshape the treatment of mental illness.”Jonathan Sporn, 2022 financing announcement
03 / The next appointment might start with a pill
Blixeprodil, or GM-1020, takes another route: an oral NMDA receptor antagonist. The ambition is rapid antidepressant activity with a tolerability profile suited to simpler delivery. Oral dosing could remove an infusion from the process. Whether it can support at-home treatment safely remains a development question, not a service patients can presently order.
In January 2026, Gilgamesh announced results from a 46-patient Phase 2a proof-of-concept study. At 24 hours, the company reported a 6.3-point greater reduction than placebo on the Montgomery-Åsberg Depression Rating Scale, with p=0.006. The study also included repeated dosing and follow-up. Its small size makes the findings a reason to investigate further, rather than a settled verdict.
A proof-of-concept signal. Not an approval, a population-wide prediction, or a comparison with other medicines.
One methodological wrinkle deserves attention. Residual effects carried into the second dosing period of the crossover study, so the efficacy analysis used only the first period, as prespecified. The experiment’s tidy comparison ran into the candidate’s persistence. Readers should retain that detail alongside the encouraging headline.
04 / Chemistry has more than one door
The independent company also kept its separate AbbVie neuroplastogen collaboration. Announced in May 2024, that agreement included $65 million upfront and eligibility for up to $1.95 billion in aggregate option fees and milestones, plus royalties. These non-hallucinogenic compounds aim to promote brain plasticity. That research agreement and the bretisilocin acquisition are distinct transactions.
GM-3009 addresses another obstacle: the cardiovascular toxicity that has complicated ibogaine’s pharmaceutical development. A $14 million, multi-year National Institute on Drug Abuse grant supports toxicology, manufacturing and early clinical work on Gilgamesh’s analog for opioid use disorder. Better cardiac safety is the assignment. Demonstrating it in people is part of the work.
Gilgamesh combines behavioral, electrophysiological, molecular and machine-learning approaches to characterize candidates. AI sits inside that research process; it is not a standalone product customers license from a software menu. The team’s disclosed experience spans pharmaceutical companies and academic laboratories. Its investor’s description of an execution-oriented team fits the emphasis on moving chemistry into clinical experiments.
05 / The lesson is in the bottleneck
Gilgamesh occupies a crowded neighborhood. Compass Pathways pursues psilocybin treatment for treatment-resistant depression; Delix Therapeutics pursues non-hallucinogenic neuroplastogens. Gilgamesh’s distinction is its combination of novel chemistry, several mechanisms and pharmaceutical dealmaking. Different studies and populations prevent a neat ranking of whose medicine is better.
The useful lesson to copy is a design question: what makes a promising treatment difficult to deliver? Duration, route and tolerability belong in that question from the beginning. The approach depends on biological benefits surviving the chemical changes, larger studies confirming early signals, and delivery becoming practical. A shorter appointment cannot rescue an ineffective medicine. Gilgamesh’s next chapter will be decided in those experiments.