VLR199

VLR199 is an investigational recombinant fusion protein (specifically an ActRIIA-Fc ligand trap) being developed for the treatment of pulmonary arterial hypertension (PAH) and related cardiopulmonary diseases, including secondary pulmonary hypertension. Originally discovered by Paragon Labs and developed by Velaris (which was acquired by Alaunos Therapeutics in October 2026), VLR199 is designed to replicate and improve upon the clinically validated pharmacology of Merck's Winrevair (sotatercept). By acting as a ligand trap, VLR199 binds to and sequesters activins and growth differentiation factors (GDFs), thereby inhibiting the activin-related signaling pathways that drive pathological pulmonary vascular remodeling. The program is currently in preclinical development, with an IND or CTA filing planned for the second half of 2027 and clinical proof-of-concept data expected in 2028.