GRI Bio, Inc.

We are a clinical-stage biopharmaceutical company focused on discovering, developing, and commercializing innovative therapies for serious diseases linked to dysregulated immune responses, specifically inflammatory, fibrotic, and autoimmune disorders. Our primary product candidate is GRI-0621, an oral inhibitor of type 1 invariant Natural Killer T (iNKT) cells. The active pharmaceutical ingredient in GRI-0621 is tazarotene, a synthetic retinoid acid receptor-beta and gamma selective agonist. Tazarotene is currently approved in the United States for topical treatment of psoriasis and acne. Although there are no approved oral formulations of tazarotene, as of December 31, 2025, it has been evaluated in over 1,700 patients as an oral product for up to 52 weeks. We are developing GRI-0621 to treat severe fibrotic lung diseases, including idiopathic pulmonary fibrosis (IPF). IPF is a progressive fibrotic lung disease affecting approximately 140,000 people in the United States, with up to 40,000 new cases annually in the United States, and an estimated 3 million globally. While two approved therapies exist for lung fibrosis, they have not improved overall survival and are associated with significant side effects leading to poor patient adherence. Preliminary and topline data from our trials with GRI-0621, and earlier trials with oral tazarotene, indicate that GRI-0621 is well-tolerated and inhibits iNKT cell activity. Activated iNKT cells are elevated in patients with IPF, primary sclerosing cholangitis (PSC), metabolic dysfunction-associated steatohepatitis (MASH), alcoholic liver disease (ALD), systemic lupus erythematosus (SLE), multiple sclerosis (MS), and ulcerative colitis (UC), and correlate with more severe disease. We recently evaluated GRI-0621 in a randomized, double-blind, multi-center, 2-arm Phase 2a clinical trial for IPF patients.