Atsena Therapeutics Wins EMA Orphan Designation for Two Retinal Gene Therapy Candidates

Atsena Therapeutics announced that the EMA has granted orphan designation to both of its clinical-stage gene therapy candidates for inherited retinal diseases: ATSN-101 for Leber congenital amaurosis 1 (LCA1), and ATSN-201 for X-linked retinoschisis (XLRS).¹ The EMA grants orphan designation to drugs and biologics addressing rare, life-threatening, or chronically debilitating conditions, and the designation provides benefits including reduced regulatory fees, clinical protocol assistance, research grants, and up to 10 years of market exclusivity in the EU.¹

Patrick Ritschel, chief executive officer of Atsena, said, "Receiving orphan designation from the EMA for both ATSN-101 and ATSN-201 underscores that these programs address significant unmet needs for patients who currently have no treatment options. With our pivotal trial for ATSN-201 enrolling rapidly and our global pivotal trial for ATSN-101 on track to begin later this year, we are closer than ever to delivering gene therapies that can change the trajectory of these inherited retinal diseases for patients in the US, Europe and beyond."¹

Both candidates already held Orphan Drug, Rare Pediatric Disease, Fast Track, and Regenerative Medicine Advanced Therapy (RMAT) designations from the FDA prior to this EMA decision.¹

How does ATSN-201 work, and what data support it?

ATSN-201 uses AAV.SPR, a proprietary capsid engineered to spread laterally beyond the initial subretinal injection site, allowing it to reach photoreceptors across the central retina without the surgical risk of detaching the fovea.¹ XLRS is caused by mutations in the RS1 gene, which encodes retinoschisin, a protein that helps maintain retinal layer structure; without it, patients develop schisis, an abnormal splitting of retinal layers that causes progressive, uncorrectable vision loss.¹ Approximately 30,000 males in North America and Europe have XLRS, and no disease-specific treatment is currently approved.¹

In the completed phase 1/2 portion of the LIGHTHOUSE trial, ATSN-201 became the first XLRS gene therapy to demonstrate evidence of efficacy and safety, with most patients showing foveal schisis closure alongside improvements in retinal and visual function, effects that have remained durable out to two years in some patients.¹ The pivotal phase 3 cohort began dosing in June 2026 and is enrolling ahead of schedule at US sites, with European and UK sites expected to open later this year.¹

How does ATSN-101 work, and what data support it?

ATSN-101 targets LCA1, caused by mutations in the GUCY2D gene, one of the most common forms of Leber congenital amaurosis and a condition with no approved treatments.¹ In a completed phase 1/2 trial, patients receiving the high dose showed durable, clinically significant vision improvements out to 36 months post-treatment, with no drug-related serious adverse events reported.¹ Atsena is developing ATSN-101 through a strategic collaboration with Nippon Shinyaku, which holds exclusive US and Japan rights while Atsena retains rights for the rest of the world, and expects to begin a global pivotal phase 3 trial later this year across sites in the US, Europe, and Japan.¹

VeonGen Therapeutics' VG801, an AAV gene therapy for Stargardt disease, followed a comparable designation path. Caroline Man Xu, PhD, co-founder and CEO of VeonGen, said of that RMAT designation, "Receiving RMAT designation is strong recognition of VG801's therapeutic potential for Stargardt disease, the most common inherited retinal disorder with no approved therapies."²

What happens next?

With EMA orphan designation now secured for both programs, Atsena's near-term focus remains execution: continuing to enroll the ATSN-201 pivotal cohort across its expanding US, European, and UK site network, and initiating the ATSN-101 global pivotal trial later this year across the US, Europe, and Japan.¹

References

1. Atsena Therapeutics Receives Orphan Designation from the European Medicines Agency (EMA) for ATSN-101 and ATSN-201. (2026 Jan 23). GlobeNewswire. https://www.globenewswire.com/news-release/2026/07/23/3332096/0/en/atsena-therapeutics-receives-orphan-designation-from-the-european-medicines-agency-ema-for-atsn-101-and-atsn-201.html?
2. Lavery P. (2025 Aug 22). VeonGen's Stargardt Disease Gene Therapy Gets FDA RMAT Status. BioPharm International. https://www.biopharminternational.com/view/veongen-stargardt-disease-gene-therapy-gets-fda-rmat-status