Newleos Therapeutics announced that the first participant has been dosed in the company’s third Phase 1b study of NTX-1955, designed to evaluate its safety and tolerability in generalized anxiety disorder (GAD). NTX-1955 is Newleos’ GABAA-γ1 positive allosteric modulator (PAM) and represents a potential first-in-class treatment for GAD. The company previously announced initial dosing of participants in two other Phase 1b trials being conducted in the EU in July and September 2025.
The Phase 1b study is a multi-center randomized, double-blind, placebo-controlled trial being conducted in the U.K. in adults with GAD. Data from the three Phase 1b studies are expected to inform dose selection and design of a Phase 2 efficacy study. The study is actively enrolling participants ages 18 to 55 years with current diagnoses of GAD. Participants are randomized to receive NTX-1955 at one of two possible dose levels or matched placebo once daily for two weeks, visiting the clinic six times over a six-week study period including screening and follow-up visits.
Treatment Mechanism and Current Limitations
According to Federico Bolognani, M.D., Ph.D., Newleos’ Co-founder and Chief Medical Officer, “Unlike traditional therapeutic approaches like SSRIs and benzodiazepines, our product candidate is designed to precisely target the neural circuits that drive anxiety.” GAD is the second most common mental health disorder among adults, affecting approximately 20 million adults in the U.S. alone. A substantial proportion of GAD patients remain inadequately managed by approved pharmacological therapies. While first-line SSRIs and SNRIs are ineffective in roughly half of all patients, second-line benzodiazepines, while highly efficacious, are not recommended for long-term use due to sedation, potential for misuse and dependence, and cognitive impairment. NTX-1955 has shown dose-dependent anxiolytic activity in several preclinical models matching benzodiazepines’ efficacy without the side effect profile of classical benzodiazepines.
This article is an AI-assisted summary. All facts and figures are drawn from the original report: https://www.biospace.com/press-releases/newleos-announces-dosing-of-first-participant-in-u-k-phase-1b-study-of-ntx-1955-in-generalized-anxiety-disorder