FDA Clears IND for RAG-1C saRNA candidate targeting proliferative vitreoretinopathy

The US Food and Drug Administration (FDA) has cleared an Investigational New Drug (IND) application for Ractigen Therapeutics’ RAG-1C, a small activating RNA (saRNA) candidate, for the treatment of proliferative vitreoretinopathy (PVR).1 PVR is a severe fobrotic complication caused by rhegmatogenous retinal detachment (RRD), which has no FDA-approved treatment currently. This clearance, announced July 31, gives way for the first clinical evaluation of an saRNA-based therapy in ocular disease in the United States.1

"PVR represents a critical unmet clinical need with zero approved drug options," said Long-Cheng Li, MD, founder and CEO of Ractigen Therapeutics, in a company statement. "We look forward to initiating our clinical studies to bring this transformative therapy to patients worldwide."¹

The US clearance follows an IND approval granted by China's National Medical Products Administration (NMPA/CDE) in March 2025, positioning RAG-1C as the first saRNA therapeutic candidate in ophthalmology to enter simultaneous clinical development in both countries, according to the company.¹

Phase 1 trial overview

The Phase 1 trial will evaluate the safety, tolerability, pharmacokinetics, and preliminary efficacy of RAG-1C in patients undergoing surgical repair of retinal detachment and who are considered at high risk for PVR development. The details of the trial design, enrollment criteria, primary endpoints, and expected timeline have not yet been announced at the time of this article.

RAG-1C is intended to be administered as a single intravitreal injection at the time of surgery—a one-time intraoperative approach described as potentially providing long-lasting anti-fibrotic protection.¹

Clinical context and unmet need

Occuring in approximately 5% to 10% of all RRD cases, PVR is the leading cause of surgical failure following RRD repair, as well as in up to 40% of severe ocular trauma cases, according to Ractigen.¹

PVR is characterized by aberrant proliferation and migration of retinal pigment epithelium (RPE) cells and fibroblasts, leading to membrane formation on the retinal surface, tractional retinal detachment, and permanent vision loss.

Despite decades of research into adjunctive pharmacologic strategies—including 5-fluorouracil, low molecular weight heparin, and daunorubicin—no agent has achieved FDA approval for PVR prevention or treatment.² Current management of the condition relies entirely on surgical intervention, which is associated with high rates of recurrence and repeated procedures,² representing a substantial gap in the retinal surgical armamentarium.

Mechanism of action and drug background

RAG-1C employs RNA activation (RNAa), a gene-regulatory mechanism in which small double-stranded RNAs induce transcriptional upregulation of endogenous target genes—an approach mechanistically distinct from RNA interference (RNAi), which silences gene expression.³

Specifically, RAG-1C is designed to upregulate the p21 (CDKN1A) gene, a cyclin-dependent kinase inhibitor that mediates cell cycle arrest. By increasing p21 protein expression in target ocular cells, the therapy aims to inhibit cellular proliferation and myofibroblast transformation—the core pathophysiological drivers of PVR—without inducing cytotoxicity, according to the company.¹

The candidate is delivered via Ractigen's proprietary LiCO™ (Lipid-Conjugated Oligonucleotide) platform, a non-lipid nanoparticle conjugated delivery system designed for tissue-targeted distribution following intravitreal injection. The company reports that the platform has demonstrated favorable ocular tolerability and minimal systemic exposure in GLP toxicology studies, though peer-reviewed preclinical data specific to RAG-1C in ocular tissues have not been independently published at the time of this writing.¹

Interpretive framing and limitations

IND clearance indicates the FDA has determined that available preclinical data are sufficient to permit initiation of human studies; it does not constitute evidence of clinical efficacy or safety. Phase 1 trials are primarily powered to assess safety and dose-finding parameters, and preliminary efficacy signals—if observed—must be interpreted with caution given sample sizes and the absence of randomized controls at this stage.

The novelty of the saRNA platform in ophthalmology also means that the ocular tolerability profile of this therapeutic class in humans remains to be established in the clinical setting. Additionally, PVR's multifactorial pathophysiology—involving inflammatory, proliferative, and contractile cellular processes—raises questions about whether targeting a single gene pathway will be sufficient to meaningfully alter clinical outcomes.

Note: Key published trial data and peer-reviewed preclinical results for RAG-1C have not yet appeared in the indexed literature, limiting independent assessment of the mechanistic and translational evidence base at this stage.

References

1. Ractigen Therapeutics. Ractigen Therapeutics Announces U.S. FDA IND Clearance for First-in-Class saRNA Candidate RAG-1C to Treat Proliferative Vitreoretinopathy. News release. July 31, 2026. https://www.prnewswire.com/news-releases/ractigen-therapeutics-announces-us-fda-ind-clearance-for-first-in-class-sarna-candidate-rag-1c-to-treat-proliferative-vitreoretinopathy-302839921.html

2. Idrees S, Sridhar J, Kuriyan AE. Proliferative vitreoretinopathy: a review. Int Ophthalmol Clin. 2019;59(1):221-240. doi:10.1097/IIO.0000000000000258

3. Voutila J, Reebye V, Roberts TC, et al. Development and mechanism of small activating RNA targeting CEBPA, a regulator of liver function and hepatocellular carcinoma. Mol Ther. 2017;25(12):2705-2714. doi:10.1016/j.ymthe.2017.07.018

4. Schwartz SG, Flynn HW Jr, Wang X, Scott IU. Proliferative vitreoretinopathy. Curr Pharm Des. 2020;26(39):4895-4900. doi:10.2174/1381612826666200812221732