GRI Bio Inc. (NASDAQ: GRI) presented Phase 2a data for GRI-0621, an oral retinoic acid receptor agonist, at the European Respiratory Society Congress in Barcelona. The study, GRI-0621-IPF-02, enrolled 35 patients with idiopathic pulmonary fibrosis (IPF) and randomized them in a 2:1 ratio to receive GRI-0621 at 4.5 mg once daily or placebo for 12 weeks. Eighty percent of patients received background pirfenidone or nintedanib, standard-of-care antifibrotic therapy.
The study measured outcomes across four modalities: whole-blood RNA sequencing, serum extracellular matrix biomarkers, spectral flow cytometry, and clinical readouts. Eighteen anchor transcripts reached statistical significance in RNA sequencing, and 13 flow cytometry readouts reached p < 0.05. Forced vital capacity (FVC) was an exploratory endpoint, and the study was not powered for statistical significance. At week 12, 39% of GRI-0621-treated patients experienced an FVC increase compared to 20% on placebo. Patients receiving background antifibrotic therapy showed a 50% FVC increase. The placebo-adjusted FVC change from baseline at week 12 was +99 mL overall and +139 mL on background standard-of-care therapy. Eight percent of GRI-0621-treated patients experienced an FVC decline compared to 20% on placebo. Ten post hoc sensitivity analyses of the FVC endpoint remained directionally positive, with estimates ranging from +40 to +65 mL overall and +67 to +89 mL on background standard-of-care.
The safety profile of GRI-0621 was favorable, with no serious treatment-emergent adverse events reported in the GRI-0621 arm versus 8% on placebo. Adverse events reported were dry lips, dry skin, arthralgia, and myalgia (all Grade 1–2). Treatment-emergent cough was reported in 0% of GRI-0621 patients versus 25% on placebo.
GRI Bio stated that the findings support advancing GRI-0621 into a longer-duration study.
