GRI Bio Presents Phase 2a Data Mapping GRI-0621's Nine-Pillar Mechanism of Action in IPF

Multi-modal biomarker evidence from GRI Bio's Phase 2a study of GRI-0621 (oral tazarotene) in idiopathic pulmonary fibrosis is now detailed enough to inform regulatory submission strategy and CMC planning for fibrotic disease programs. The company presented the dataset at the 2026 European Respiratory Society Congress in Barcelona, covering a late-breaking oral session and three posters.

The 35-patient GRI-0621-IPF-02 study integrated four independent measurement modalities applied to the same population: whole-blood RNA sequencing of 72 curated anchor genes, a 12-marker serum extracellular matrix neo-epitope panel, 28-color spectral flow cytometry of paired blood and bronchoalveolar lavage samples, and clinical and patient-reported readouts. Eighteen anchor transcripts reached statistical significance at FDR<0.05, including ALDH1A2, confirming pharmacodynamic engagement of the retinoic acid receptor pathway. Thirteen flow cytometry readouts reached p<0.05.

The concordant signals resolve into nine pre-specified mechanistic pillars: immune re-balancing, reduced lung injury, myofibroblast inhibition, fibrolysis, basement-membrane repair, re-epithelialization, FVC stabilization, antitussive effect, and gastrointestinal protection. Each pillar is supported by direction-consistent findings from at least two independent modalities, a design choice that strengthens the evidentiary weight of any future regulatory package. For QA and regulatory leads, the multi-modal corroboration approach mirrors the totality-of-evidence standard increasingly expected under ICH Q10-aligned development frameworks.

On the mechanistic side, a Th2-to-Th1 immune shift was observed at both RNA and protein levels, with CCR4, IL-4, and IL-13 downregulated by sequencing and mirrored in flow cytometry. Myofibroblast inhibition was evidenced through coordinated downregulation along the TGF-β axis, including SMAD6/7 and PMEPA1 upregulation as negative-feedback regulators, corroborated by reduced serum fibrillar collagen synthesis markers PRO-C3 and PRO-C6. Increased HLA-DR on lung macrophages indicated immune reprogramming rather than suppression.

Lung function data showed approximately 2x to 2.5x as many GRI-0621-treated patients experienced an FVC increase compared with placebo. Placebo-adjusted FVC change from baseline at Week 12 was +99 mL overall and +139 mL in patients on background standard-of-care antifibrotic therapy. GRI Bio stated the totality of Phase 2a findings supports advancement into a longer-duration study.

The FVC signal at Week 12, set against the nine-pillar mechanistic framework, will serve as the primary benchmark against which a longer-duration trial's endpoints and biomarker panel design will be evaluated.

Source: GRI Bio, Inc. via GlobeNewswire, 8 September 2026.