GRI Bio Presents Phase 2a GRI-0621 Lung-Function and Biomarker Data at ERS

GRI Bio presented Phase 2a data for GRI-0621 in idiopathic pulmonary fibrosis at the European Respiratory Society Congress in Barcelona on Sunday, putting lung function, translational biomarkers and tolerability at the center of the company’s case for advancing the oral drug into a larger study. The 35-patient GRI-0621-IPF-02 trial was randomized, double-blind and placebo-controlled, with participants assigned 2:1 to 4.5 mg of GRI-0621 or placebo once daily for 12 weeks.

The lung-function signal was an exploratory finding rather than the study’s primary endpoint. GRI Bio has reported a 99 mL placebo-adjusted improvement from baseline in forced vital capacity, or FVC, for the overall GRI-0621 arm at 12 weeks, rising to 139 mL among participants who were also taking background antifibrotic therapy. The company’s latest SEC filing also says 39% of treated participants had an increase in FVC, compared with 20% on placebo, while 8% of treated participants had an FVC decline of at least 10%, versus 20% in the placebo arm.

Sunday’s program included three morning posters and a late-breaking oral presentation. GRI Bio had announced the ERS presentations in August, and the official congress program lists the oral presentation as OA2380 alongside posters PA895, PA896 and PA897. The presentation gives the clinical-stage biotechnology company a scientific forum for data it has been releasing in stages since late 2025, rather than marking the first disclosure of every numerical result.

FVC findings strengthen the development case, but the study is small

FVC measures the amount of air a person can forcibly exhale after taking a full breath and is widely used to track functional decline in pulmonary fibrosis. In GRI Bio’s Phase 2a study, pulmonary function was exploratory, while the primary endpoint was safety and tolerability. That distinction matters because the trial was designed mainly to characterize safety and biological activity, not to provide the statistical evidence expected from a registrational study.

GRI Bio’s June-quarter filing says the 99 mL placebo-adjusted FVC change was observed across the treated arm, with the 139 mL figure applying to participants who received GRI-0621 on top of standard-of-care antifibrotics. Roughly 80% of all study participants were taking either pirfenidone or nintedanib in the background. The filing also cautions that spirometry can vary from visit to visit and depends on patient effort, which can create outliers in a small data set.

The company has performed sensitivity analyses around the FVC data, but the larger point for investors is that the functional signal is directionally consistent with the biomarker story GRI Bio is trying to establish. A short, 35-patient Phase 2a trial cannot determine whether GRI-0621 will durably slow IPF progression or improve clinical outcomes. It can, however, help the company select endpoints, sample size and trial duration for the next stage of development.

The ERS Congress 2026 program lists the lung-function poster as PA897, titled around a positive effect on FVC after 12 weeks of treatment. The late-breaking oral session also combines lung function with safety and translational biomarkers, suggesting that the scientific argument being presented is based on several lines of evidence rather than FVC alone.

Biomarker changes support GRI Bio’s fibrosis-remodeling hypothesis

GRI-0621 is an oral retinoic acid receptor beta/gamma-selective agonist that GRI Bio is developing to inhibit type 1 invariant natural killer T cells, or iNKT cells. The company believes those immune cells participate in inflammatory and fibrotic signaling in IPF. In the Phase 2a program, it has measured serum collagen markers, immune-cell activity and gene expression to test whether the drug produces biological changes consistent with that mechanism.

Among the more concrete collagen findings, GRI Bio reported that PRO-C6, a marker of type VI collagen formation, fell 3% from baseline in treated participants while rising 12% in the placebo-plus-standard-of-care group. C6M, a marker of type VI collagen degradation, increased 6% with GRI-0621 and decreased 3% in the comparison group. The company interprets that pattern as suggestive of a shift away from ongoing fibrogenesis and toward collagen breakdown, but the biomarker changes are not themselves proof that lung fibrosis has been reversed in patients.

GRI Bio has also reported changes in type IV collagen markers that it links to the alveolar basement membrane. PRO-C4 rose 9% from baseline in the treated group and fell 2% in the placebo group, while C4Ma3 increased less in the GRI-0621 arm than in the comparison arm. Gene-expression and immune-profiling analyses added another layer: treated subjects showed increased type 1-associated interferon-gamma and reductions in several type 2 and type 3 cytokines, including IL-4, IL-13, IL-17A and IL-22, along with lower TGF-beta in multiple immune-cell populations.

Those findings are why GRI Bio’s ERS biomarker poster describes a repair phenotype with anti-fibrotic and pro-resolving effects. That language remains the company’s interpretation of an early-stage data set. The study’s size, short duration and reliance on exploratory and translational endpoints mean the biological signals need to be tested against clinical outcomes in a larger and longer trial.

Safety was the Phase 2a study’s primary focus. GRI Bio has said there were no serious adverse events in the active arm and one in the placebo arm. Dry skin, dry lips, muscle pain and joint pain were among the most commonly reported adverse events, and the company has also highlighted descriptive differences in cough, shortness of breath, weight loss and diarrhea between the two groups. Those symptom comparisons are potentially useful for planning future studies, but the trial was too small to treat them as definitive evidence of symptom benefit.

The next hurdle is a larger trial and the capital to fund it

For GRI Bio, the ERS presentations arrive after a regulatory step that could help the program if it advances successfully. The U.S. Food and Drug Administration granted orphan drug designation to GRI-0621 for IPF in June. The designation can provide development incentives and, if the drug is eventually approved for the orphan indication and other requirements are met, potential eligibility for seven years of U.S. market exclusivity. It does not establish efficacy or make approval more likely on its own.

The company has already begun discussing the next clinical stage with the FDA. In its June-quarter Form 10-Q, GRI Bio said it had requested a Type C meeting, received written feedback and was evaluating its clinical strategy. It intends to seek another FDA meeting on a proposed adaptive Phase 2b/3 design. The filing also makes clear that there is no assurance the agency will agree with that design.

Financing is a separate constraint. GRI Bio reported about $10.9 million of cash and cash equivalents at June 30 and said its current operating plan could fund planned expenses into the second quarter of 2027. That runway assumes only preliminary work toward additional GRI-0621 studies. The company said it would need substantial additional capital or resources to complete further dose-ranging and other clinical trials, and its filing includes substantial doubt about its ability to continue as a going concern without additional financing.

That makes the practical value of the ERS appearance broader than scientific visibility alone. A clearer Phase 2a package can support discussions with regulators, prospective partners and investors as GRI Bio works toward a larger study. The next material milestones are whether the FDA accepts the company’s proposed development path and whether GRI Bio secures enough capital or partnership support to carry GRI-0621 into that next trial.