Gilgamesh Pharmaceuticals reported top-line results from its Phase IIa study of GM-2505, an experimental 5-HT2A receptor agonist and 5-HT releaser being developed for major depressive disorder (MDD). The drug achieved a 94% remission rate about a month after just two treatment sessions, the company said.The randomised study evaluated 40 patients with moderate-to-severe MDD who received either 10 mg of GM-2505 or a low-dose psychoactive comparator via intravenous infusion on the first day, followed by a 15-mg dose of GM-2505 for everyone on day 15.10-point advantageResults showed a significant and "clinically impactful" reduction in Montgomery-Åsberg Depression Rating Scale (MADRS) scores. Within 24 hours of the first dose, patients on GM-2505 saw an 18.5-point drop in their depression scores.After two weeks, the 10-mg group had a 21.6-point reduction on MADRS, nearly 10 points better than those who had started on the low-dose psychoactive comparator. By day 29, following the second dose, the high-dose group had a 28-point reduction from baseline, with benefits lasting up to day 74 without additional treatment.The medication was well-tolerated with no serious adverse events reported, and most side effects resolved within two hours of administration.Later-stage trials"GM-2505's rapid and sustained antidepressant effect fits seamlessly into the existing two-hour, in-clinic treatment model," said CEO Jonathan Sporn. The company plans to advance GM-2505 into later-stage trials, alongside its other lead programme, an oral NMDA receptor antagonist called GM-1020 that is completing a Phase IIa study in MDD this year.The trial results come on the heels of Gilgamesh's $2-billion partnership with AbbVie last May, aimed at neuroplastogens that mimic the therapeutic potential of psychedelics without hallucinations or the need for in-office administration and supportive care. However, GM-2505 is not part of that collaboration (see – Spotlight On: Neuroplastogens hit the mainstream in 2024. What's next for trip-less psychedelics?).The field of neuropsychiatry saw a surge of investment and deal-making over the last year or two (see – Spotlight On: Neuropsychiatry startups take centre stage). Arguably one of largest deals in the space, Bristol Myers Squibb is banking that Cobenfy (xanomeline/trospium chloride), a key asset acquired through its $14-billion takeover of Karuna Therapeutics — and since approved for schizophrenia — can drive an entire pipeline of products. Meanwhile, AbbVie's $8.7-billion buyout of Cerevel Therapeutics hit turbulence after a key asset stumbled in two trials — though the company is still looking for a silver lining.