BOSTON– Newleos Therapeutics, Inc., a clinical-stage biotechnology company developing treatments for neuropsychiatric disorders, announced today that the first subject has been dosed in its second Phase 1b study of NTX-1955 in the European Union. NTX-1955 is a GABAA-γ1 positive allosteric modulator (PAM) being evaluated as a novel therapy for generalized anxiety disorder (GAD). The milestone follows the initiation of the company’s first Phase 1b trial of NTX-1955 in July 2025.
The company also reported that the U.S. Food and Drug Administration has cleared its Investigational New Drug application for NTX-1472, a selective vasopressin 1a (V1a) receptor antagonist. This clearance paves the way for a Phase 2 randomized, double-blind, placebo-controlled study in adults with social anxiety disorder (SAD).
“I am extremely proud of the significant clinical and regulatory progress that Newleos has achieved in the short time since our launch earlier this year,” said David Donabedian, Ph.D., Founding Chief Executive Officer of Newleos and Executive Partner at Longwood Fund. “With NTX-1955 advancing in two Phase 1b studies and FDA clearance to begin a Phase 2 study of NTX-1472, we are making meaningful strides toward our mission of delivering next-generation pharmacotherapies to the millions of patients living with anxiety disorders who remain underserved by existing treatments.”
“These are critical milestones for Newleos, for anxiety patients and for the clinical validation of our novel oral therapies targeting GABAA-γ1 and V1a receptors,” said Federico Bolognani, M.D., Ph.D., Co-Founder and Chief Medical Officer at Newleos. “Existing treatments for both GAD and SAD are severely limited due to their undesirable side effects, and pharmacologic treatment is an integral part of a comprehensive plan for patients suffering from anxiety disorders. We look forward to presenting initial results from our ongoing NTX-1955 studies at upcoming industry meetings and beginning initial dosing in our Phase 2 trial of NTX-1472.”
Generalized anxiety disorder affects roughly 20 million adults in the United States, making it the second most common mental health disorder among adults. Social anxiety disorder impacts a similar population, representing about 7 percent of U.S. adults annually, with higher prevalence among teens and women. Current pharmacological treatments for both disorders often fall short due to lack of efficacy, side effects, or risk of dependence.
NTX-1955 has been designed to selectively engage GABAergic transmission in the amygdala, a brain region central to anxiety regulation, potentially avoiding the sedation and cognitive impairment associated with benzodiazepines. NTX-1472, meanwhile, targets V1a receptors that influence social behavior and anxiety circuits, offering another pathway to address unmet needs in patients with SAD. Both compounds were licensed from Roche and have demonstrated favorable safety and tolerability in earlier Phase 1 studies.
