Newleos Therapeutics is a clinical-stage neuroscience company based in Boston, Massachusetts, focused on developing novel treatments for neuropsychiatric disorders. The company was co-founded by Longwood Fund and seasoned leaders in central nervous system (CNS) drug development.

In February 2025, Newleos closed an oversubscribed $93.5 million Series A financing round, led by Goldman Sachs Alternatives, with participation from Novo Holdings A/S, Longwood Fund, DCVC Bio, and Arkin Bio Capital. The funds are allocated to advance proof-of-concept clinical trials across the company's programs.

The company's clinical-stage pipeline was in-licensed from Roche and includes multiple oral small molecules targeting novel mechanisms across a broad range of indications, including generalized anxiety, social anxiety, substance use disorders, and cognitive impairment. Newleos' lead clinical program, NTX-1955 (RO7308480), is a first-in-class GABA_A-γ1 selective positive allosteric modulator designed to treat anxiety disorders with a differentiated mechanism of action without the side effects of currently available treatments.