FDA grants orphan drug designation to DSP-3077 for retinitis pigmentosa

The US Food and Drug Administration (FDA) has granted orphan drug designation to DSP-3077, an investigational induced pluripotent stem cell (iPSC)–derived retinal sheet therapy for the treatment of retinitis pigmentosa (RP), according to a March 23, 2026, announcement from Sumitomo Pharma America, Inc. The designation highlights ongoing efforts to address a rare, progressive retinal degeneration for which treatment options remain limited.

For clinicians, the designation signals regulatory support for early-stage development of regenerative approaches in inherited retinal disease, though clinical efficacy and long-term safety data for DSP-3077 are not yet available. The therapy is currently under investigation in a phase 1/2 clinical trial.

Trial and Regulatory Overview

DSP-3077 is being evaluated in an ongoing phase 1/2 study (NCT06891885), designed to assess safety, tolerability, and preliminary efficacy in patients with RP. According to the sponsor, the investigational product consists of allogeneic retinal sheets derived from iPSCs and engineered into multilayered retinal tissue structures containing photoreceptor precursors.

The study involves surgical implantation of these retinal sheets into the eyes of affected patients. As of this report, no peer-reviewed efficacy or safety outcomes from the trial have been published. Early-phase trials of cell-based retinal therapies typically focus on feasibility, engraftment, and adverse event profiling rather than definitive visual outcomes.

The FDA’s orphan drug designation is granted to therapies targeting conditions affecting fewer than 200,000 individuals in the United States and provides incentives including tax credits for clinical development, waiver of certain user fees, and eligibility for 7 years of market exclusivity upon approval.¹

Clinical Context

Retinitis pigmentosa encompasses a heterogeneous group of inherited retinal dystrophies characterized by progressive degeneration of rod and cone photoreceptors. Patients typically present with nyctalopia and peripheral visual field constriction, with eventual central vision loss in advanced stages.

The prevalence of RP is estimated at approximately 1 in 3,000 to 1 in 5,000 individuals worldwide.² Disease progression varies by genetic subtype, with more than 80 causative genes identified.³ Despite advances in genetic diagnostics, therapeutic options remain limited.

Currently, the only FDA-approved therapy specifically targeting an inherited retinal dystrophy is voretigene neparvovec for RPE65 mutation–associated retinal disease.⁴ Management for most RP patients remains supportive, including low vision rehabilitation and monitoring for complications such as cystoid macular edema.

Drug and Mechanistic Background

DSP-3077 represents a regenerative medicine approach aimed at replacing degenerated photoreceptors rather than modifying disease progression at the genetic level. iPSC-derived retinal organoids have emerged as a promising platform for generating transplantable retinal tissue, with preclinical studies demonstrating the potential for structural integration and partial restoration of visual function.⁵

Unlike gene therapies that target specific mutations, cell-based therapies such as DSP-3077 may offer broader applicability across genetically diverse RP populations. However, challenges remain, including immune compatibility, long-term graft survival, and functional synaptic integration with host retinal circuitry.

Other investigational strategies in RP include gene-agnostic neuroprotective agents, optogenetic therapies, and additional stem cell–based approaches, though most remain in early clinical development.

Interpretation and Expert Perspective

The orphan drug designation for DSP-3077 reflects regulatory recognition of unmet need rather than validation of clinical efficacy. While regenerative retinal therapies are an area of active investigation, translation from preclinical success to clinically meaningful vision improvement has historically been difficult.

Early-phase trials of retinal cell therapies have demonstrated variable outcomes, with some evidence of anatomical integration but inconsistent functional gains.⁶ As such, clinicians should interpret this development as exploratory, pending robust clinical data.

Limitations and Next Steps

At present, no published clinical data are available for DSP-3077. Key unanswered questions include the durability of the implanted tissue, the degree of visual function improvement, and the risk of adverse events such as proliferative vitreoretinopathy or immune rejection.

Further data from the ongoing phase 1/2 trial will be critical to determine whether this approach can progress to later-stage studies. Long-term follow-up will also be necessary to assess safety in the context of cell-based transplantation.

References

1. US Food and Drug Administration. Orphan Drug Designation Program. Accessed March 23, 2026. https://www.fda.gov/industry/developing-products-rare-diseases-conditions/orphan-drug-designation-program

2. Hartong DT, Berson EL, Dryja TP. Retinitis pigmentosa. Lancet. 2006;368(9549):1795-1809. https://doi.org/10.1016/S0140-6736(06)69740-7

3. Daiger SP, Sullivan LS, Bowne SJ. Genes and mutations causing retinitis pigmentosa. Clin Genet. 2013;84(2):132-141. https://doi.org/10.1111/cge.12203

4. Russell S, Bennett J, Wellman JA, et al. Efficacy and safety of voretigene neparvovec for RPE65-mediated inherited retinal dystrophy. N Engl J Med. 2017;376(1):7-16. https://doi.org/10.1056/NEJMoa1609468

5. Gonzalez-Cordero A, West EL, Pearson RA, et al. Photoreceptor precursors derived from pluripotent stem cells integrate and restore vision. Nature. 2013;497(7451): 547-551. https://doi.org/10.1038/nature12156

6. Mead B, Tomarev S. Bone marrow-derived mesenchymal stem cells-derived exosomes promote survival of retinal ganglion cells through miRNA-dependent mechanisms. Stem Cells Transl Med. 2017;6(4):1273-1285. https://doi.org/10.1002/sctm.16-0428