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12-month results from Part A of LIGHTHOUSE Trial reinforce ATSN-201’s favorable safety profile and durable structural and functional benefits in patients with X-linked retinoschisis

Three-year data from Phase 1/2 trial confirm durable efficacy and tolerability of ATSN-101 in patients with Leber congenital amaurosis type 1

Atsena is advancing ATSN-201 and ATSN-101 into pivotal clinical trials in 2026

DURHAM, NC, May 7, 2026 – Atsena Therapeutics, a clinical-stage gene therapy company focused on using the life-changing power of genetic medicine to reverse or prevent blindness, this week presented data from three studies at the Association for Research in Vision and Ophthalmology (ARVO) Annual Meeting in Denver, CO. The presentations included 12-month data for ATSN-201 in X-linked retinoschisis (XLRS), three-year data for ATSN-101 in Leber congenital amaurosis type 1 (LCA1), and a novel approach to measuring functional vision in inherited retinal diseases.

“Atsena is advancing two gene therapies into pivotal clinical trials — ATSN-201 for XLRS and ATSN-101 for LCA1 — making us one of a very small number of gene therapy companies with two programs in late-stage clinical development. The data we presented at ARVO 2026 reinforce our confidence in both,” said Kenji Fujita, MD, Chief Medical Officer of Atsena Therapeutics. “The 12-month Part A results for ATSN-201 demonstrate durable structural improvements and meaningful functional gains in XLRS patients, supported by a consistently favorable safety profile. The ATSN-101 data confirm durable vision improvements and sustained tolerability through at least three years post-treatment.”

ATSN-201 in X-linked Retinoschisis: 12-Month Part A Results:

Lesley Everett, MD, PhD, Assistant Professor of Ophthalmology at the Casey Eye Institute at Oregon Health & Science University, presented 12-month safety and efficacy results from Part A of the Phase 1/2/3 LIGHTHOUSE Trial. ATSN-201 continued to demonstrate a favorable safety profile across all nine adult patients, with no drug-related serious adverse events, no dose-limiting toxicities, and no patient discontinuations. Foveal schisis closure was maintained in seven of nine treated eyes at 12 months — a result not observed in untreated eyes — and statistically significant improvements in microperimetry, best-corrected visual acuity, and low-luminance visual acuity were observed in treated eyes. Patient screening is underway for Part C of the LIGHTHOUSE Trial, the study’s pivotal Phase 3 portion, with enrollment expected to complete by end of Q1 2027 and a Biologics License Application (BLA) filing targeted for 2028.

ATSN-101 in Leber Congenital Amaurosis: 36-Month Results:

Artur Cideciyan, PhD, Research Professor of Ophthalmology at the Scheie Eye Institute at the University of Pennsylvania, presented three-year safety and efficacy data from the Phase 1/2 clinical trial evaluating ATSN-101 in 15 patients with LCA1. Patients treated at the high dose continued to demonstrate clinically meaningful improvements in dark-adapted full-field stimulus testing (FST), with a mean improvement of approximately 20 decibels — a 100-fold gain in light sensitivity — that has been durable through at least three years post-treatment. ATSN-101 was well-tolerated with no drug-related serious adverse events and no patient discontinuations. Atsena expects to initiate a global pivotal Phase 3 trial for ATSN-101 in the second half of 2026.

Modified Multi-Luminance Mobility Test (modMLMT):

Alexandra Garafalo, Research Project Manager at the Scheie Eye Institute at the University of Pennsylvania, presented a poster describing a modified version of the Multi-Luminance Mobility Test (modMLMT) developed to better capture functional vision benefits in patients with retained rod function, such as those with LCA1. The modMLMT demonstrated treatment effect in more patients treated with ATSN-101 than the standard MLMT, and Atsena plans to use the modMLMT in the pivotal clinical trial evaluating ATSN-101 for LCA1.

About X-linked Retinoschisis (XLRS)
XLRS is a monogenic X-linked disease caused by mutations in the RS1 gene which encodes retinoschisin, a protein secreted primarily by photoreceptors. RS1 is localized to the extracellular surface of rods, cones and bipolar cells. XLRS is characterized by schisis, or abnormal splitting of retinal layers, which causes impaired visual acuity that is not correctable with glasses and leads to progressive vision loss and ultimately blindness. XLRS primarily affects males and is typically diagnosed in early childhood. Approximately 30,000 males in the U.S. and EU have XLRS, for which there are currently no approved treatments.

About ATSN-201
ATSN-201 is Atsena’s investigational gene therapy leveraging AAV.SPR, a novel, laterally spreading capsid designed to efficiently target photoreceptors in the central retina while avoiding the surgical risks of foveal detachment. It is currently being evaluated in the Phase 1/2/3 LIGHTHOUSE Trial, which consists of three parts (A, B and C) and six cohorts. The Phase 1/2 portion includes cohorts 1-3 (Part A) and cohorts 4-5 (Part B), while cohort 6 (Part C) is the pivotal Phase 3 portion of the study.

ATSN-201 is the first XLRS gene therapy to demonstrate preliminary evidence of efficacy and safety in a Phase 1/2 trial, with the majority of patients demonstrating improvements in retinal structure (foveal schisis closure) and meaningful improvements in retinal and visual function as assessed by microperimetry, best-corrected visual acuity and low-luminance visual acuity. ATSN-201 has demonstrated a favorable safety profile and has been well-tolerated for up to one year post-treatment. This best-in-class gene therapy product candidate has received Regenerative Medicine Advanced Therapy, Fast Track, Rare Pediatric Disease and Orphan Drug Designations from the U.S. Food and Drug Administration and Orphan Designation from the European Medicines Agency. Enrollment for this study is ongoing. For more information, visit ClinicalTrials.gov (Identifier: NCT05878860).

About GUCY2D-associated Leber congenital amaurosis (LCA1)
LCA1 is a monogenic eye disease that disrupts the function of the retina. It is caused by mutations in the GUCY2D gene and results in early and severe vision impairment or blindness. LCA1 is one of the most common forms of LCA, affecting approximately 20 percent of patients who live with this group of inherited retinal diseases. There are currently no approved treatments for LCA1.

About ATSN-101
ATSN-101 is a first-in-class, investigational, subretinal AAV5 gene therapy being developed for Leber congenital amaurosis type 1 (LCA1). ATSN-101 has completed a Phase 1/2 trial with positive results, and Atsena expects to initiate a global pivotal Phase 3 clinical trial evaluating ATSN-101 in the second half of 2026. As part of a strategic collaboration, Nippon Shinyaku Co., Ltd. has exclusive commercial rights for ATSN-101 in the U.S. and Japan, while Atsena retains commercial rights in the rest of the world.

About Atsena Therapeutics
Atsena is a clinical-stage gene therapy company developing best-in-class treatments for the reversal or prevention of blindness from inherited retinal diseases. The company’s lead program is evaluating ATSN-201 in a pivotal clinical trial for X-linked retinoschisis (XLRS), a genetic condition that is typically diagnosed in childhood and leads to blindness later in life. The company’s proprietary pipeline also includes gene therapies in development for Usher Syndrome Type 1B and for Stargardt Disease. Atsena is also developing ATSN-101, a first-in-class, investigational gene therapy for Leber congenital amaurosis type 1 (LCA1), as part of its exclusive strategic collaboration with Nippon Shinyaku Co., Ltd. ATSN-101 has completed a Phase 1/2  trial with positive results (https://doi.org/10.1016/s0140-6736(24)01447-8), and Atsena expects to initiate a global pivotal Phase 3 clinical trial evaluating ATSN-101 in the second half of 2026.

Founded by pioneers in ocular gene therapy, Atsena is led by an experienced team dedicated to addressing the needs of patients with vision loss. For more information, please visit https://atsenatx.com/.

Investor and Media Contact:
Argot Partners
[email protected]

Business Contact:
[email protected]

Six-month data from adult Cohort 4 show structural and functional improvements and a favorable safety profile; early safety data from pediatric Cohort 5 are consistent with adult cohorts

Enrollment underway in pivotal Part C cohort; FDA is aligned with primary endpoint of microperimetry at 52 weeks; BLA filing is targeted for 2028

DURHAM, NC, May 4, 2026 – Atsena Therapeutics, a clinical-stage gene therapy company focused on using the life-changing power of genetic medicine to reverse or prevent blindness, presented interim six-month results from Part B of the Phase 1/2/3 LIGHTHOUSE Trial evaluating ATSN-201 in patients with X-linked retinoschisis (XLRS) at the Foundation Fighting Blindness Retinal Therapeutics Innovation Summit on May 1, 2026, in Denver, CO.

“Part B of our LIGHTHOUSE study is delivering exactly as we expected — a favorable safety profile, schisis resolution, and functional improvements at six months that closely replicate what we observed at the same time point in Part A of the study. Foveal schisis closure was observed in four of six treated adults, and there was no structural change observed in untreated control subjects or untreated contralateral eyes. The kinetics of microperimetry response across Cohort 4 mirror what we saw in Part A of the study. No serious adverse events were observed in any Part B cohort, including in our pediatric patients,” said Shannon Boye, PhD, Co-Founder and Chief Scientific Officer of Atsena.

“Enrollment in the pivotal Part C cohort is now underway, and this marks a significant milestone for patients with XLRS and for Atsena. ATSN-201 is the first gene therapy to advance to a registrational trial for XLRS, a disease with no approved treatments. We remain on track for a BLA filing in 2028,” said Kenji Fujita, MD, Chief Medical Officer of Atsena.

Part B of the study is evaluating nine adults and three pediatric patients with XLRS. The adult cohort is divided into three arms: two arms evaluating different injection volumes and an untreated control arm. Patients in the control arm will have the option to receive treatment after one year of observation. This part of the study will continue to assess safety and efficacy, including microperimetry, visual acuity, and macular structure.

Safety and efficacy highlights from the interim six-month Part B data include:

• The kinetics of structural and functional responses in Cohort 4 were consistent with those observed in Cohorts 1-3.
  • Foveal schisis closure at Month 6 was confirmed in 4 of 6 treated adults (67%) in Cohort 4. Notably, none of the three untreated control subjects and none of the six untreated contralateral eyes demonstrated foveal schisis closure.
  • Microperimetry response at Month 6 for Part B closely mirrors that observed for Part A at the same time point.
• A favorable safety profile was observed across all Part B cohorts
  • No serious adverse events (SAEs), no instances of macular hole formation or retinal detachment, and no subject discontinuations were observed.
  • Subretinal deposits observed in a subset of subjects in Cohort 4 were resolved with transient steroid treatment.
• A clean safety profile was observed in pediatric subjects (Cohort 5, ages 8–12), with no SAEs, no subretinal deposits, no macular hole formation, no retinal detachment, and no discontinuations.

Part C of the LIGHTHOUSE Trial is the Phase 3 pivotal portion of the study, enrolling a total of 76 patients with XLRS across leading clinical sites in North America and Europe. Patients are separated into two groups: treatment and control. Patients in the treatment arm will receive treatment with ATSN-201, while patients in the control arm will be observed for 12 months and then have the option to receive treatment with ATSN-201. The primary endpoint is microperimetry at 52 weeks, as aligned with the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA), with visual acuity and optical coherence tomography (OCT) as key secondary endpoints. Patient screening is underway, and enrollment is expected to be completed by the end of the first quarter of 2027. Data from the Phase 3 cohort are expected to support a Biologics License Application (BLA) filing in 2028.

About X-linked Retinoschisis (XLRS)
XLRS is a monogenic X-linked disease caused by mutations in the RS1 gene which encodes retinoschisin, a protein secreted primarily by photoreceptors. RS1 is localized to the extracellular surface of rods, cones and bipolar cells. XLRS is characterized by schisis, or abnormal splitting of retinal layers, which causes impaired visual acuity that is not correctable with glasses and leads to progressive vision loss and ultimately blindness. XLRS primarily affects males and is typically diagnosed in early childhood. Approximately 30,000 males in the U.S. and EU have XLRS, for which there are currently no approved treatments.

About ATSN-201
ATSN-201 is Atsena’s investigational gene therapy leveraging AAV.SPR, a novel, laterally spreading capsid designed to efficiently target photoreceptors in the central retina while avoiding the surgical risks of foveal detachment. It is currently being evaluated in the Phase 1/2/3 LIGHTHOUSE Trial, which consists of three parts (A, B and C) and six cohorts. The Phase 1/2 portion includes cohorts 1-3 (Part A) and cohorts 4-5 (Part B), while cohort 6 (Part C) will serve as the Phase 3 portion of the study.

ATSN-201 is the first XLRS gene therapy to demonstrate preliminary evidence of efficacy and safety in a Phase 1/2 trial, with the majority of patients demonstrating improvements in retinal structure (foveal schisis closure) and meaningful improvements in retinal and visual function as assessed by microperimetry, best-corrected visual acuity and low-luminance visual acuity. ATSN-201 has demonstrated a favorable safety profile and has been well-tolerated for at least one year post-treatment. This best-in-class gene therapy product candidate has received Regenerative Medicine Advanced Therapy, Fast Track, Rare Pediatric Disease and Orphan Drug Designations from the U.S. Food and Drug Administration and Orphan Designation from the European Medicines Agency. Enrollment for this study is ongoing. For more information, visit ClinicalTrials.gov (Identifier: NCT05878860).

About AAV.SPR
AAV.SPR, one of Atsena’s novel capsids, spreads laterally beyond the subretinal injection site to enable safe and efficient transduction of the central retina when injected into areas outside the macula. A preclinical study in non-human primates demonstrated that AAV.SPR promotes transgene expression well beyond subretinal injection bleb margins. This is in contrast to benchmark AAV vectors, which remain confined to the original bleb margins. At clinically relevant doses, AAV.SPR efficiently transduces foveal cones without the need for surgical detachment and has a favorable safety profile relative to benchmark capsids. For more information about the preclinical study and how AAV.SPR works, visit https://atsenatx.com/our-approach/laterally-spreading-aav/.

About Atsena Therapeutics
Atsena is a clinical-stage gene therapy company developing best-in-class treatments for the reversal or prevention of blindness from inherited retinal diseases. The company’s lead program is evaluating ATSN-201 in a pivotal clinical trial for X-linked retinoschisis (XLRS), a genetic condition that is typically diagnosed in childhood and leads to blindness later in life. The company’s proprietary pipeline also includes gene therapies in development for Usher Syndrome Type 1B and for Stargardt Disease. Atsena is also developing ATSN-101, a first-in-class, investigational gene therapy for Leber congenital amaurosis type 1 (LCA1), as part of its exclusive strategic collaboration with Nippon Shinyaku Co., Ltd. ATSN-101 has completed a Phase 1/2  trial with positive results (https://doi.org/10.1016/s0140-6736(24)01447-8), and Atsena expects to initiate a global pivotal Phase 3 clinical trial evaluating ATSN-101 in the second half of 2026.

Founded by pioneers in ocular gene therapy, Atsena is led by an experienced team dedicated to addressing the needs of patients with vision loss. For more information, please visit https://atsenatx.com/.

Investor and Media Contact:
Argot Partners
[email protected]

Business Contact:
[email protected]

 

DURHAM, NC, April 23, 2026 – Atsena Therapeutics, a clinical-stage gene therapy company focused on using the life-changing power of genetic medicine to reverse or prevent blindness, today announced upcoming presentations at the Foundation Fighting Blindness (FFB) Retinal Therapeutics Innovation Summit, the Association for Research in Vision and Ophthalmology (ARVO) Annual Meeting, and the American Society of Gene & Cell Therapy (ASGCT) Annual Meeting.

Details of Atsena’s presentations and poster sessions are as follows:

May 1: FFB Retinal Therapeutics Innovation Summit (Denver, Colorado)

Title: Safety and Efficacy of ATSN-201 in Patients with X-linked Retinoschisis: An Update on the LIGHTHOUSE Study
Session: Retinal Genetic Augmentation: Clinical
Date and Time: Friday, May 1, 4:20-4:35 p.m. MT
Location: Sheraton Denver Downtown Hotel
Presenter: Shannon Boye, Ph.D., Atsena Therapeutics

May 3-7: ARVO Annual Meeting (Denver, Colorado)

Title: Safety and Efficacy of ATSN-201 in Patients with X-linked Retinoschisis: 12-month Dose Finding Results of LIGHTHOUSE study
Session: Stem Cell and Gene Therapy
Date and Time: Thursday, May 7, 12:00-12:15 p.m. MT
Location: Bluebird Ballroom 1B
Presentation Number: 5500
Presenter: Lesley Everett, M.D., Ph.D., OHSU Casey Eye Institute

Title: Safety and Efficacy of ATSN-101 in Patients with Leber Congenital Amaurosis Caused by Biallelic Variants in GUCY2D (LCA1): Durability Through 3 Years Post-treatment
Session: Retinal Translational Research
Date and Time: Wednesday, May 6, 2:45-3:00 p.m. MT
Location: Mile High 4E
Presentation Number: 4480
Presenter: Artur Cideciyan, Ph.D., Scheie Eye Institute, University of Pennsylvania

Title: Modified Multi-Luminance Mobility Test (modMLMT) to Evaluate Therapeutic Benefit to Night Vision Mediated by Rod Photoreceptors
Session: Stem Cell and Gene Therapy
Date and Time: Wednesday, May 6, 2:00-3:45 p.m. MT
Location: Exhibit Hall
Posterboard Number: 0631
Presenter: Alexandra Garafalo, Scheie Eye Institute, University of Pennsylvania

May 11-15: ASGCT Annual Meeting (Boston, Massachusetts)

Title: Safety and Efficacy of ATSN-201 in Patients with X-linked Retinoschisis: 12-month Dose Finding Results of the LIGHTHOUSE Study
Session: In Vivo Clinical Trials in Eye and Muscle Disorders
Date and Time: Friday, May 15, 4:45-5:00 p.m. ET
Location: MCEC Room 2010ABC (Level 2)
Abstract Number: 507
Presenter: Laura Pardon, O.D., Ph.D., Atsena Therapeutics

About Atsena Therapeutics
Atsena is a clinical-stage gene therapy company developing best-in-class treatments for the reversal or prevention of blindness from inherited retinal diseases. The company’s lead program is evaluating ATSN-201 in a pivotal clinical trial for X-linked retinoschisis (XLRS), a genetic condition that is typically diagnosed in childhood and leads to blindness later in life. The company’s proprietary pipeline also includes gene therapies in development for Usher Syndrome Type 1B and for Stargardt Disease. Atsena is also developing ATSN-101, a first-in-class, investigational gene therapy for Leber congenital amaurosis type 1 (LCA1), as part of its exclusive strategic collaboration with Nippon Shinyaku Co., Ltd. ATSN-101 has completed a Phase 1/2 trial with positive results (https://doi.org/10.1016/s0140-6736(24)01447-8), and Atsena expects to initiate a global pivotal Phase 3 clinical trial evaluating ATSN-101 in the second half of 2026. Founded by pioneers in ocular gene therapy, Atsena is led by an experienced team dedicated to addressing the needs of patients with vision loss. For more information, please visit https://atsenatx.com/.

Investor and Media Contact:
Argot Partners
[email protected]

Business Contact:
[email protected]

Patient screening to begin this month

DURHAM, NC, April 20, 2026 – Atsena Therapeutics, a clinical-stage gene therapy company focused on using the life-changing power of genetic medicine to reverse or prevent blindness, today announced that the independent Data Monitoring Committee (DMC) for the Phase 1/2/3 LIGHTHOUSE Trial evaluating ATSN-201 for the treatment of X-linked retinoschisis (XLRS) has completed its review of accumulated data from Parts A and B of the study and has recommended that the Company proceed with enrollment of the pivotal Part C cohort. Atsena will initiate Part C screening this month.

“We are excited that the DMC has recommended that we proceed with the pivotal Part C cohort,” said Kenji Fujita, MD, Chief Medical Officer of Atsena Therapeutics. “This recommendation reflects the strength of the safety and efficacy data we have accumulated to date and brings us one step closer to delivering what we believe will be the first approved therapy for patients with XLRS.”

Part C Enrollment Details

Part C of the LIGHTHOUSE Trial will serve as the Phase 3 pivotal portion of the study, enrolling a total of 76 patients with XLRS across leading clinical sites in North America and Europe. Patients will be separated into two groups: treatment and control. Patients in the treatment arm will receive bilateral or unilateral treatment with ATSN-201, while patients in the control arm will be observed for 12 months and then have the option to receive treatment with ATSN-201. Patient screening is expected to begin in April 2026, with enrollment expected to be completed by the end of the first quarter of 2027. Data from the Phase 3 cohort are expected to support a Biologics License Application (BLA) filing in 2028.

About X-linked Retinoschisis (XLRS)

XLRS is a monogenic X-linked disease caused by mutations in the RS1 gene which encodes retinoschisin, a protein secreted primarily by photoreceptors. RS1 is localized to the extracellular surface of rods, cones and bipolar cells. XLRS is characterized by schisis, or abnormal splitting of retinal layers, which causes impaired visual acuity that is not correctable with glasses and leads to progressive vision loss and ultimately blindness. XLRS primarily affects males and is typically diagnosed in early childhood. Approximately 30,000 males in the U.S. and EU have XLRS, for which there are currently no approved treatments.

About ATSN-201

ATSN-201 is Atsena’s investigational gene therapy leveraging AAV.SPR, a novel, laterally spreading capsid designed to efficiently target photoreceptors in the central retina while avoiding the surgical risks of foveal detachment. It is currently being evaluated in the Phase 1/2/3 LIGHTHOUSE Trial, which consists of three parts (A, B and C) and six cohorts. The Phase 1/2 portion includes cohorts 1-3 (Part A) and cohorts 4-5 (Part B), while cohort 6 (Part C) will serve as the Phase 3 portion of the study.

ATSN-201 is the first XLRS gene therapy to demonstrate preliminary evidence of efficacy and safety in a Phase 1/2 trial, with the majority of patients demonstrating improvements in retinal structure (foveal schisis closure) and meaningful improvements in retinal and visual function as assessed by microperimetry, best-corrected visual acuity and low-luminance visual acuity. ATSN-201 has demonstrated a favorable safety profile and has been well-tolerated for at least one year post-treatment. This best-in-class gene therapy product candidate has received Regenerative Medicine Advanced Therapy, Fast Track, Rare Pediatric Disease and Orphan Drug Designations from the U.S. Food and Drug Administration and Orphan Designation from the European Medicines Agency. Enrollment for this study is ongoing. For more information, visit ClinicalTrials.gov (Identifier: NCT05878860).

About AAV.SPR

AAV.SPR, one of Atsena’s novel capsids, spreads laterally beyond the subretinal injection site to enable safe and efficient transduction of the central retina when injected into areas outside the macula. A preclinical study in non-human primates demonstrated that AAV.SPR promotes transgene expression well beyond subretinal injection bleb margins. This is in contrast to benchmark AAV vectors, which remain confined to the original bleb margins. At clinically relevant doses, AAV.SPR efficiently transduces foveal cones without the need for surgical detachment and has a favorable safety profile relative to benchmark capsids. For more information about the preclinical study and how AAV.SPR works, visit https://atsenatx.com/our-approach/laterally-spreading-aav/.

About Atsena Therapeutics

Atsena is a clinical-stage gene therapy company developing best-in-class treatments for the reversal or prevention of blindness from inherited retinal diseases. The company’s lead program is evaluating ATSN-201 in a pivotal clinical trial for X-linked retinoschisis (XLRS), a genetic condition that is typically diagnosed in childhood and leads to blindness later in life. The company’s proprietary pipeline also includes gene therapies in development for Usher Syndrome Type 1B and for Stargardt Disease. Atsena is also developing ATSN-101, a first-in-class, investigational gene therapy for Leber congenital amaurosis type 1 (LCA1), as part of its exclusive strategic collaboration with Nippon Shinyaku Co., Ltd. ATSN-101 has completed a Phase 1/2  trial with positive results (https://doi.org/10.1016/s0140-6736(24)01447-8), and Atsena expects to initiate a global pivotal Phase 3 clinical trial evaluating ATSN-101 in the second half of 2026.

Founded by pioneers in ocular gene therapy, Atsena is led by an experienced team dedicated to addressing the needs of patients with vision loss. For more information, please visit https://atsenatx.com/.

Investor and Media Contact:
Argot Partners
[email protected]

Business Contact:
[email protected]

AAV.SPR capsid delivers RS1 to foveal photoreceptors from a safe, peripheral injection site, overcoming problems experienced with conventional AAV capsids

Atsena’s lead AAV.SPR program, ATSN-201, is now advancing into a pivotal clinical trial in patients with X-linked retinoschisis

DURHAM, NC, March 27, 2026 – Atsena Therapeutics, a clinical-stage gene therapy company focused on reversing or preventing blindness from inherited retinal diseases, today announced the publication of a peer-reviewed study in Molecular Therapy that establishes the scientific rationale for AAV.SPR, its proprietary laterally spreading capsid, as a critical enabling technology for retinal gene therapy. The study provides rigorous preclinical evidence that lateral spread is not simply a performance advantage; it is necessary for delivering certain gene therapies to the central retina safely and effectively.

Building on this foundational research, ATSN-201, Atsena’s investigational gene therapy delivering a functional RS1 gene via the AAV.SPR capsid, is currently being evaluated in the Phase 1/2/3 LIGHTHOUSE Trial. XLRS is a monogenic X-linked disease caused by mutations in RS1, which encodes retinoschisin, a protein secreted primarily by photoreceptors that plays a critical role in maintaining retinal cell organization and synaptic function. The disease is characterized by the formation of schisis cavities — abnormal splitting of the retinal layers — that cause impaired visual acuity beginning in early childhood and ultimately lead to blindness. XLRS affects approximately 30,000 males in the United States and European Union, and there are currently no approved treatments.

“AAV.SPR represents a technological breakthrough in ocular gene therapy. For decades, the field has grappled with a fundamental tradeoff: either place the vector directly under the fragile fovea and risk iatrogenic damage or inject it intravitreally and fail to achieve therapeutic levels of gene expression while also contending with inflammation,” said Shannon E. Boye, Ph.D., Co-Founder and Chief Scientific Officer of Atsena Therapeutics. “This publication demonstrates that AAV.SPR can transduce virtually all foveal cones from a safe, peripheral injection site. It also reveals why conventional capsids can never achieve the same result, even in theory: RS1 stays where the vector goes, and a non-spreading capsid simply cannot get to the fovea from the periphery. These data provide a rigorous scientific foundation for the exciting results we are now seeing in our clinical trial.”

The Problem AAV.SPR Addresses: Subretinal Injection of Conventional AAV Capsids and Intravitreal Delivery Fall Short for XLRS and Many Other Retinal Diseases

The fovea, the small, densely packed region of the central retina responsible for sharp, detailed vision, is the primary therapeutic target in many inherited retinal diseases (IRDs). Yet reaching it safely has been a formidable hurdle in the retinal gene therapy field.

The treatment of photoreceptor-mediated diseases relies on efficient gene delivery to these cells, with therapeutically meaningful transduction levels attained only when adeno-associated virus (AAV) vectors are delivered subretinally. Conventional AAV capsids remain confined to the margins of the subretinal bleb formed at the point of injection. Delivering genes to foveal photoreceptors has therefore historically required placing the injection directly underneath the fovea, surgically detaching this irreplaceable structure in the process. In diseases such as XLRS, where characteristic schisis cavities make the central retina fragile and prone to damage, foveal detachment is strongly contraindicated. This created an apparent impasse: the cells that most needed treatment could not be safely reached.

Two earlier clinical trials conducted by the National Eye Institute and by AGTC, Inc. attempted to work around this constraint by delivering vector intravitreally, injecting it into the gel-filled cavity in front of the retina rather than beneath it. Neither trial demonstrated efficacy, and intravitreally delivered AAV led to significant, chronic inflammation in some patients. As the new publication explains, no AAV capsid has demonstrated efficient photoreceptor transduction following intravitreal administration in nonhuman primates at levels sufficient for therapeutic efficacy.

A Critical Biological Insight: RS1 Goes Where the Capsid Goes — and No Further

A key finding in the new publication addresses a question central to the biology of XLRS gene therapy: Because it is a secreted protein, could RS1 expressed by photoreceptors at a peripheral injection site simply diffuse across the retina and reach the fovea on its own, even without foveal transduction?

The answer, the study shows, is no. By subretinally delivering a mixture of AAV containing a tagged RS1 construct and AAV-GFP in non-human primates (NHPs), the researchers demonstrated that RS1 protein is localized strictly to the area where photoreceptors are transduced by the AAV vector. Wherever GFP expression ended, RS1 expression ended too. RS1 does not migrate meaningfully beyond the transduced cells. To achieve RS1 expression at the fovea following peripheral subretinal injection, a spreading capsid is required.

This finding has direct implications not only for XLRS, but for all retinal gene therapies where central photoreceptor transduction is the goal and submacular injection or intravitreal injection carries unacceptable risk.

The Solution: AAV.SPR Uniquely Enables Safe Delivery to the Central Retina

AAV.SPR, Atsena’s proprietary laterally spreading capsid, was engineered to solve this problem. When administered via peripheral subretinal injection, safely away from the fovea. AAV.SPR spreads laterally well beyond the margins of the injection bleb, transducing photoreceptors across a substantially larger area of retina than conventional capsids. Key preclinical findings from the publication include:

• Foveal cone transduction without detachment. In NHP studies, two small peripheral subretinal injections of AAV.SPR transduced up to 99% of foveal cones without any surgical detachment of the fovea. Conventional AAV5, delivered identically, transduced zero foveal cones.
• Exceptional lateral spread. Transgene expression from AAV.SPR was detected more than 7 mm beyond the subretinal bleb margins in NHP retina. This spread lends itself to success in clinical outcome measures such as microperimetry which require improvements in pre-specified retinal loci.
• Higher potency at the injection site. AAV.SPR transduced a higher percentage of photoreceptors within the bleb itself relative to conventional capsids, providing greater therapeutic gene expression at equivalent doses.
• Correct RS1 localization. AAV.SPR-mediated RS1 expression in NHP retina localized correctly to photoreceptor inner segments and photoreceptor-bipolar cell synapses, precisely mimicking the natural pattern of RS1 expression.

The study also demonstrates that the same lateral spreading properties that make AAV.SPR suited for XLRS are broadly applicable to other IRDs in which safe delivery to the central retina is the goal, including Usher syndrome and conditions where foveal cones are the last remaining functional photoreceptors.

From Bench to Clinic: ATSN-201 Advances into Pivotal Trial

The clinical data accumulated to date in the LIGHTHOUSE Trial validate the potential of the AAV.SPR approach in patients. ATSN-201 has demonstrated a favorable safety profile and has been well-tolerated thus far, with no related serious adverse events. The majority of treated patients have shown improvements in retinal structure, including foveal schisis closure, as well as meaningful functional improvements assessed by microperimetry and visual acuity. This is the first time any gene therapy has been shown to reverse this structural hallmark of XLRS and provide functional improvements. Having completed enrollment in the Phase 1/2 portions of the study, Atsena is preparing to advance ATSN-201 into the pivotal Phase 3 portion of the study.

About Atsena Therapeutics

Atsena is a clinical-stage gene therapy company developing best-in-class treatments for the reversal or prevention of blindness from inherited retinal diseases. The company’s lead program is evaluating ATSN-201 in a pivotal clinical trial for X-linked retinoschisis (XLRS), a genetic condition that is typically diagnosed in childhood and leads to blindness later in life. The company’s proprietary pipeline also includes gene therapies in development for Usher Syndrome Type 1B and for Stargardt Disease. Atsena is also developing ATSN-101, a first-in-class, investigational gene therapy for Leber congenital amaurosis type 1 (LCA1), as part of its exclusive strategic collaboration with Nippon Shinyaku Co., Ltd. ATSN-101 has completed a Phase 1/2 trial with positive results (https://doi.org/10.1016/s0140-6736(24)01447-8), and Atsena expects to initiate a global pivotal Phase 3 clinical trial evaluating ATSN-101 in the second half of 2026.

Founded by pioneers in ocular gene therapy, Atsena is led by an experienced team dedicated to addressing the needs of patients with vision loss. For more information, please visit https://atsenatx.com/.

Investor and Media Contact:
Argot Partners
[email protected]

Business Contact:
[email protected]

Lexington, MA and Durham, NC – January 20, 2026 – Genezen, a leading gene therapy contract development and manufacturing organization (CDMO), and Atsena Therapeutics (“Atsena”), a clinical-stage gene therapy company focused on using the life-changing power of genetic medicine to reverse or prevent blindness, today announced a strategic manufacturing partnership to advance the clinical development and commercial manufacturing of Atsena’s pipeline programs powered by novel adeno-associated virus (AAV) technology engineered to overcome the hurdles presented by inherited retinal diseases. Atsena’s lead program is evaluating ATSN-201 in the pivotal LIGHTHOUSE study for the treatment of X-linked retinoschisis (XLRS) and is on track for a potential Biologics License Application filing in early 2028.

Under the collaboration, Genezen will leverage its viral vector manufacturing expertise to support clinical and commercial manufacturing using Atsena’s existing platform. The partnership is designed to provide a streamlined and cost-efficient path to commercial manufacturing, reinforcing Genezen’s track record of supporting late-stage programs through regulatory and validation readiness.

“With this strategic partnership, we will leverage our deep technical capability and commercial capacity to support Atsena’s pipeline programs,” said Steve Favaloro, Chairman and Chief Executive Officer of Genezen. “We are honored to support Atsena as they advance their critical gene therapies into pivotal clinical trials and move closer to providing life-changing treatments for patients with vision loss.”

“Genezen’s demonstrated technical capabilities make them an ideal partner to support the commercial development and advancement of our pipeline,” said Michael Kelly, Senior Vice President, Chemistry, Manufacturing and Controls of Atsena Therapeutics. “This collaboration brings us closer to our mission of improving the quality of life of patients with inherited retinal disease with gene therapies that prevent or reverse genetic blindness.”

About Genezen

Genezen is a best-in-class gene therapy CDMO with over a decade of experience and state-of-the-art viral vector manufacturing facilities. From concept to commercial scale, Genezen partners with innovators to deliver life-saving gene and cell therapies worldwide. Learn more at genezen.com or follow Genezen on LinkedIn.

About Atsena Therapeutics

Atsena is a clinical-stage gene therapy company developing best-in-class treatments for the reversal or prevention of blindness from inherited retinal diseases. The company’s lead program is evaluating ATSN-201 for X-linked retinoschisis (XLRS), a genetic condition that is typically diagnosed in childhood and leads to blindness later in life. Atsena plans to initiate enrollment in the pivotal Part C cohort of the ATSN-201 LIGHTHOUSE clinical trial in the first quarter of 2026. The company’s proprietary pipeline also includes gene therapies in development for Usher Syndrome Type 1B and for Stargardt Disease. Atsena is also developing ATSN-101, a first-in-class, investigational gene therapy for Leber congenital amaurosis type 1 (LCA1), as part of its exclusive strategic collaboration with Nippon Shinyaku Co., Ltd. ATSN-101 has completed a Phase I/II trial with positive results (https://doi.org/10.1016/s0140-6736(24)01447-8), and Atsena expects to initiate a pivotal global clinical trial evaluating ATSN-101 in the second half of 2026.

Founded by pioneers in ocular gene therapy, Atsena is led by an experienced team dedicated to addressing the needs of patients with vision loss. For more information, please visit https://atsenatx.com/.

 

Genezen Media Contact: Meg Bor [email protected]

Atsena Therapeutics Media Contact: Argot Partners [email protected]

Atsena Completes Dosing in Part B of the Phase I/II/III LIGHTHOUSE Trial Evaluating ATSN-201 to Treat X-linked Retinoschisis and Announces Plans for Initiation of Pivotal Part C Cohort

Enrollment of pivotal cohort expected to begin in Q1 2026; ATSN-201 BLA submission
on track for early 2028

DURHAM, NC, January 8, 2026 – Atsena Therapeutics, a clinical-stage gene therapy company focused on using the life-changing power of genetic medicine to reverse or prevent blindness, today announced that dosing is complete in patients enrolled across all adult and pediatric cohorts in Part B of the Phase I/II/III Lighthouse Trial evaluating subretinal injection of ATSN-201 for the treatment of X-linked retinoschisis (XLRS). The Company plans to initiate enrollment of the pivotal Part C cohort of patients in the first quarter of 2026.

“Given the significant unmet needs of patients of all ages with XLRS, we are proud to complete dosing in Part B of the LIGHTHOUSE Trial, which includes pediatric and adult cohorts,” said Kenji Fujita, MD, Chief Medical Officer of Atsena Therapeutics. “All three pediatric patients have been successfully dosed with ATSN-201 with no surgical complications. Preliminary safety data remain favorable, and no serious adverse events related to treatment have been reported. We look forward to building upon the encouraging structural and functional benefits reported in Part A of the study as we conduct follow-up for Part B and look ahead to the enrollment of Part C, the study’s pivotal cohort.”

“I’m pleased with the meaningful progress we continue to achieve in the ongoing LIGHTHOUSE study as we work to bring this potential first- and best-in-class gene therapy to patients with XLRS,” said Patrick Ritschel, MBA, Chief Executive Officer of Atsena Therapeutics. “We have alignment with the FDA on the design of the pivotal Part C cohort, and we look forward to beginning enrollment in the first quarter of 2026. Results from this cohort will support a potential regulatory submission, bringing us one step closer to delivering the first ever approved therapy for XLRS.”

Part B of the ongoing multicenter LIGHTHOUSE study is evaluating a total of nine adults and three pediatric patients with XLRS. Adults are separated into three groups: low volume, high volume and control. Patients in the control group will be observed off therapy for one year and then have the option to receive treatment. Pediatric patients received the low volume. In July 2025, the U.S. Food and Drug Administration (FDA) agreed to the expansion of the study to serve as a pivotal trial.

Part C of the ongoing multicenter clinical trial will serve as the Phase III pivotal portion of the study and evaluate a total of 56 adult and pediatric patients with XLRS recruited at leading U.S. and international clinical sites. Patients will be separated into two groups: treatment and control. Patients in the treatment group will receive bilateral or unilateral treatment with ATSN-201, and patients in the control group will be observed for 12 months and then have the option to receive treatment with ATSN-201. The Phase III cohort is expected to support a Biologics License Application (BLA), anticipated in early 2028.

About X-linked Retinoschisis (XLRS)

XLRS is a monogenic X-linked disease caused by mutations in the RS1 gene which encodes retinoschisin, a protein secreted primarily by photoreceptors. RS1 is localized to the extracellular surface of rods, cones and bipolar cells. XLRS is characterized by schisis, or abnormal splitting of retinal layers, which causes impaired visual acuity that is not correctable with glasses and leads to progressive vision loss and ultimately blindness. XLRS primarily affects males and is typically diagnosed in early childhood. Approximately 30,000 males in the U.S. and EU have XLRS, for which there are currently no approved treatments.

About ATSN-201

ATSN-201 is Atsena’s investigational gene therapy leveraging AAV.SPR, a novel, laterally spreading capsid designed to efficiently target photoreceptors in the central retina while avoiding the surgical risks of foveal detachment. It is currently being evaluated in the Phase I/II/III LIGHTHOUSE Trial which consists of three parts (A, B and C) and six cohorts. The Phase I/II portion includes cohorts 1-3 (Part A) and cohorts 4-5 (Part B), while the remaining cohort 6 (Part C) will serve as the Phase III portion of the study.

ATSN-201 is the first XLRS gene therapy to demonstrate efficacy and positive safety data in a Phase I/II trial, with the majority of patients demonstrating improvements in retinal structure (foveal schisis closure) and meaningful improvements in retinal and visual function as assessed by microperimetry, best-corrected visual acuity and low-luminance visual acuity. ATSN-201 has demonstrated a favorable safety profile and has been well-tolerated for at least one year post-treatment with no serious adverse events reported to date. If approved, ATSN-201 will be the first gene therapy approved for XLRS. This best-in-class gene therapy product candidate has received Regenerative Medicine Advanced Therapy, Fast Track, Rare Pediatric Disease and Orphan Drug Designations from the U.S. Food and Drug Administration. Enrollment for this study is ongoing. For more information, visit ClinicalTrials.gov (Identifier: NCT05878860).

About AAV.SPR

AAV.SPR, one of Atsena’s novel capsids, spreads laterally beyond the subretinal injection site to enable safe and efficient transduction of the central retina (where schisis cavities predominate in XLRS patient retinas) when injected into areas outside the macula. A preclinical study in non-human primates demonstrated that AAV.SPR promotes transgene expression well beyond subretinal injection bleb margins. This is in contrast to benchmark AAV vectors, which remain confined to the original bleb margins. At clinically relevant doses, AAV.SPR efficiently transduces foveal cones without the need for surgical detachment and has a favorable safety profile relative to benchmark capsids. For more information about the preclinical study and how AAV.SPR works, visit https://atsenatx.com/our-approach/laterally-spreading-aav/.

About Atsena Therapeutics
Atsena Therapeutics (“Atsena”) is a clinical-stage gene therapy company developing best-in-class treatments for the reversal or prevention of blindness from inherited retinal diseases. The company’s lead program is evaluating ATSN-201 in an ongoing Phase I/II/III clinical trial for X-linked retinoschisis (XLRS), a genetic condition that is typically diagnosed in childhood and leads to blindness later in life. ATSN-101, Atsena’s first-in-class, investigational gene therapy for Leber congenital amaurosis type 1 (LCA1) has completed a Phase I/II trial with positive results (https://doi.org/10.1016/s0140-6736(24)01447-8). Atsena is advancing ATSN-101 toward the initiation of a global pivotal trial as part of its exclusive strategic collaboration with Nippon Shinyaku Co., Ltd. Atsena’s pipeline is powered by novel adeno-associated virus (AAV) technology tailored to overcome the hurdles presented by inherited retinal diseases. Founded by pioneers in ocular gene therapy, Atsena is led by an experienced team dedicated to addressing the needs of patients with vision loss. For more information, please visit https://atsenatx.com/.

Investor and Media Contact:
Argot Partners
[email protected]

Business Contact:
[email protected]

Atsena Therapeutics Appoints McDavid Stilwell as Chief Financial Officer

Seasoned biotech executive brings over 25 years of leadership experience across financial strategy and operations, investor relations and business development

DURHAM, NC, January 6, 2026 – Atsena Therapeutics, a clinical-stage gene therapy company focused on using the life-changing power of genetic medicine to reverse or prevent blindness, today announced the appointment of McDavid Stilwell as Chief Financial Officer.

“We’re excited to welcome McDavid to the Atsena team as we look to build upon our strong clinical progress and the momentum from our oversubscribed Series C financing,” said Patrick Ritschel, MBA, Chief Executive Officer of Atsena Therapeutics. “His strategic and operational expertise will be invaluable as we continue to advance our pipeline of therapies with first- and best-in-class potential for the treatment of inherited retinal diseases, including our ongoing Phase I/II/III LIGHTHOUSE trial of ATSN-201 in X-linked retinoschisis.”

“I’m thrilled to join Atsena during this exciting time in the company’s evolution, as we move toward initiation of the pivotal portion of the LIGHTHOUSE trial in the first quarter of 2026,” said Mr. Stilwell. “I look forward to working with the Atsena team to develop ATSN-201 and other genetic medicines with the potential to transform the lives of patients with vision loss.”

Prior to Atsena, Mr. Stilwell was CFO at CPTx. Previously, he served as CFO at Coherus Oncology, where he led the company’s financial operations during multiple U.S. product launches. Earlier in his career, he held leadership positions at biotechnology companies such as Sangamo Therapeutics, Orexigen Therapeutics, and GTx. Mr. Stilwell began his career as a Senior Investment Analyst at Shadwell Capital. He received a BA from St. John’s College and an MBA from Harvard Business School.

About Atsena Therapeutics
Atsena Therapeutics (“Atsena”) is a clinical-stage gene therapy company developing best-in-class treatments for the reversal or prevention of blindness from inherited retinal diseases. The company’s lead program is evaluating ATSN-201 in an ongoing Phase I/II/III clinical trial for X-linked retinoschisis (XLRS), a genetic condition that is typically diagnosed in childhood and leads to blindness later in life. ATSN-101, Atsena’s first-in-class, investigational gene therapy for Leber congenital amaurosis type 1 (LCA1) has completed a Phase I/II trial with positive results (https://doi.org/10.1016/s0140-6736(24)01447-8). Atsena is advancing ATSN-101 toward the initiation of a global pivotal trial as part of its exclusive strategic collaboration with Nippon Shinyaku Co., Ltd. Atsena’s pipeline is powered by novel adeno-associated virus (AAV) technology tailored to overcome the hurdles presented by inherited retinal diseases. Founded by pioneers in ocular gene therapy, Atsena is led by an experienced team dedicated to addressing the needs of patients with vision loss. For more information, please visit https://atsenatx.com/.

Investor and Media Contact:
Argot Partners
[email protected]

Business Contact:
[email protected]

Atsena Therapeutics Announces Dosing Complete for Adults in Part B of the Phase I/II/III LIGHTHOUSE Trial Evaluating ATSN-201 to Treat X-linked Retinoschisis

Pediatric dosing expected to begin in Q4 2025

Pivotal cohort expected to begin enrolling in Q1 2026

BLA submission anticipated in early 2028

Part A results demonstrated efficacy and safety; ATSN-201 on track to be first gene therapy and one-time treatment for XLRS

DURHAM, NC, September 23, 2025 – Atsena Therapeutics, a clinical-stage gene therapy company focused on using the life-changing power of genetic medicine to reverse or prevent blindness, today announced that dosing is complete in adults enrolled in Part B of the LIGHTHOUSE study, the Phase I/II/III clinical trial evaluating subretinal injection of ATSN-201 for the treatment of X-linked retinoschisis (XLRS). Based on the evaluation of preliminary data from the adult cohort, dosing of the pediatric patients is expected to begin in the fourth quarter of 2025, pending approval from the Data Monitoring Committee.

“Dosing of adult patients in all groups of Part B is now complete, and follow-up is ongoing,” said Kenji Fujita, MD, Chief Medical Officer of Atsena Therapeutics. “Preliminary safety data remain favorable, and early structural and functional readouts, including improvements in foveal schisis and retinal sensitivity, are consistent with the positive signals observed in Part A. These findings will enable initiation of pediatric dosing, a critical next step in assessing the full therapeutic potential of ATSN-201 across the XLRS patient population.”

Part B of the ongoing multicenter clinical trial is evaluating a total of nine adults and three pediatric patients with XLRS. Adults are separated into three groups: low volume, high volume and control. Patients in the control group will be observed off-therapy for one year and then have the option to receive treatment. In July 2025, the U.S. Food and Drug Administration (FDA) agreed to the expansion of the study to serve as a pivotal trial and support a Biologics License Application (BLA), anticipated in early 2028.

“Completing adult dosing in Part B of the LIGHTHOUSE study represents a meaningful milestone as we advance ATSN-201 through the pivotal trial pathway,” said Patrick Ritschel, MBA, Chief Executive Officer of Atsena Therapeutics. “The FDA’s alignment on our trial design underscores the growing momentum behind this program. With no approved therapies, we remain committed to progressing this potential first- and best-in-class gene therapy as rapidly and rigorously as possible to patients with XLRS.”

About X-linked Retinoschisis (XLRS)
XLRS is a monogenic X-linked disease caused by mutations in the RS1 gene which encodes retinoschisin, a protein secreted primarily by photoreceptors. RS1 is localized to the extracellular surface of rods, cones and bipolar cells. XLRS is characterized by schisis, or abnormal splitting of retinal layers, which causes impaired visual acuity that is not correctable with glasses and leads to progressive vision loss and ultimately blindness. XLRS primarily affects males and is typically diagnosed in early childhood. Approximately 30,000 males in the U.S. and EU have XLRS, for which there are currently no approved treatments.

About ATSN-201
ATSN-201 is Atsena’s investigational gene therapy leveraging AAV.SPR, a novel, laterally spreading capsid designed to efficiently target photoreceptors in the central retina while avoiding the surgical risks of foveal detachment. It is currently being evaluated in the Phase I/II/III LIGHTHOUSE Trial which consists of three parts (A, B and C) and six cohorts. The Phase I/II portion includes cohorts 1-3 (Part A) and cohorts 4-5 (Part B), while the remaining cohort 6 (Part C) will serve as the Phase III portion of the study.

ATSN-201 is the first XLRS gene therapy to demonstrate efficacy and positive safety data in a Phase I/II trial, with the majority of patients demonstrating improvements in retinal structure (foveal schisis closure) and meaningful improvements in retinal and visual function as assessed by microperimetry, best-corrected visual acuity and low-luminance visual acuity. ATSN-201 has demonstrated a favorable safety profile and has been well-tolerated for at least one year post-treatment with no serious adverse events reported to date. If approved, ATSN-201 will be the first gene therapy approved for XLRS. The best-in-class gene therapy product candidate has received Regenerative Medicine Advanced Therapy, Fast Track, Rare Pediatric Disease and Orphan Drug Designations from the U.S. Food and Drug Administration. Enrollment for this study is ongoing. For more information, visit ClinicalTrials.gov (Identifier: NCT05878860).

About AAV.SPR
AAV.SPR, one of Atsena’s novel capsids, spreads laterally beyond the subretinal injection site to enable safe and efficient transduction of the central retina (where schisis cavities predominate in XLRS patient retinas) when injected into areas outside the macula. A preclinical study in non-human primates demonstrated that AAV.SPR promotes transgene expression well beyond subretinal injection bleb margins. This is in contrast to benchmark AAV vectors, which remain confined to the original bleb margins. At clinically relevant doses, AAV.SPR efficiently transduces foveal cones without the need for surgical detachment and has a favorable safety profile relative to benchmark capsids. For more information about the preclinical study and how AAV.SPR works, visit https://atsenatx.com/our-approach/laterally-spreading-aav/.

About Atsena Therapeutics
Atsena Therapeutics (“Atsena”) is a clinical-stage gene therapy company developing best-in-class treatments for the reversal or prevention of blindness from inherited retinal diseases. The company’s lead program is evaluating ATSN-201 in an ongoing Phase I/II/III clinical trial for X-linked retinoschisis (XLRS), a genetic condition that is typically diagnosed in childhood and leads to blindness later in life. ATSN-101, Atsena’s first-in-class, investigational gene therapy for Leber congenital amaurosis type 1 (LCA1) has completed a Phase I/II trial with positive results (https://doi.org/10.1016/s0140-6736(24)01447-8). Atsena is advancing ATSN-101 toward the initiation of a global pivotal trial as part of its exclusive strategic collaboration with Nippon Shinyaku Co., Ltd. Atsena’s pipeline is powered by novel adeno-associated virus (AAV) technology tailored to overcome the hurdles presented by inherited retinal diseases. Founded by pioneers in ocular gene therapy, Atsena is led by an experienced team dedicated to addressing the needs of patients with vision loss. For more information, please visit https://atsenatx.com/.

Media Contact:
Gina Mangiaracina
6 Degrees
(917) 797-7904
[email protected]

Business Contact:
[email protected]

Atsena Therapeutics Announces Alignment with FDA on Regulatory Pathway to Approval for ATSN-201 in X-Linked Retinoschisis (XLRS)

Outcome of Regenerative Medicine Advanced Therapy (RMAT) meeting provides clear regulatory pathway to approval in a continuous Phase 1 / 2 / 3 study, avoiding the requirement for an additional registrational study and accelerating time to potential approval

Expansion builds on favorable efficacy and safety data from Part A of the LIGHTHOUSE study

Enrollment of pivotal cohort expected to begin in Q1 2026; BLA submission anticipated in early 2028

ATSN-201 on track to potentially be the first gene therapy and one-time treatment for XLRS

DURHAM, NC, July 9, 2025 – Atsena Therapeutics, a clinical-stage gene therapy company focused on using the life-changing power of genetic medicine to reverse or prevent blindness, today announced that the U.S. Food and Drug Administration (FDA) has agreed to the expansion of the company’s ongoing Phase 1 / 2 LIGHTHOUSE study of ATSN-201 into a continuous Phase 1 / 2 / 3 trial, enabling it to serve as a pivotal trial to support a Biologics License Application (BLA) submission for the treatment of X-linked retinoschisis (XLRS). The BLA submission is anticipated in early 2028.

“This regulatory milestone marks another significant step toward delivering a potentially first- and best-in-class gene therapy for patients living with XLRS,” said Patrick Ritschel, MBA, Chief Executive Officer of Atsena Therapeutics. “The agency’s agreement will expedite the clinical development of ATSN-201 by at least 1.5 years, compared to a separate Phase 3 clinical trial. If approved, this would be the first available treatment for XLRS, offering hope to patients and families affected by this inherited retinal disease. We’re grateful for the FDA’s continued guidance as we continue to advance this trial and prepare for filing a BLA in early 2028.”

The first- and best-in-class gene therapy product candidate has received Regenerative Medicine Advanced Therapy (RMAT), Fast Track, Rare Pediatric Disease and Orphan Drug Designations from the FDA. The regulatory feedback follows an RMAT meeting with the FDA. The Agency agreed on the proposed study design, endpoints and patient population to support potential registration. An additional cohort will be added to the ongoing multicenter trial. In the additional cohort, approximately 30 adult and pediatric patients will be randomized 1:1 between treatment and control groups. Patients in the control group will have the opportunity to receive treatment after one year. Efficacy and safety will be assessed in all patients using measures such as microperimetry, visual acuity and macular structure. The pivotal cohort is anticipated to begin enrolling in the first quarter of 2026 with a pivotal data readout expected in the second half of 2027.

“Data from the ongoing trial show that subretinal delivery of ATSN-201 has been well tolerated to date, including in patients with severe schisis cavities, and has led to encouraging improvements in both retinal structure and visual function,” said Kenji Fujita, MD, Chief Medical Officer of Atsena Therapeutics. “This program marks the first clinical use of our laterally spreading subretinal vector, offering important proof of principle for our ocular gene therapy platform. With the study’s expansion, we’re positioned to generate the pivotal data needed to potentially bring the first treatment for XLRS across the finish line.”

Currently, there are no approved treatments for XLRS, which is typically diagnosed in early childhood and affects approximately 30,000 males in the U.S. and the EU combined. The LIGHTHOUSE study is a dose-escalation and dose-expansion clinical trial in male patients ages six and older with a clinical diagnosis of XLRS caused by mutations in the RS1 gene. Enrollment for this study is ongoing. For more information, visit ClinicalTrials.gov (Identifier: NCT05878860).

About X-linked Retinoschisis (XLRS)
XLRS is a monogenic X-linked disease caused by mutations in the RS1 gene which encodes retinoschisin, a protein secreted primarily by photoreceptors. RS1 is localized to the extracellular surface of rods, cones and bipolar cells. XLRS is characterized by schisis, or abnormal splitting of retinal layers, which causes impaired visual acuity that is not correctable with glasses and leads to progressive vision loss and ultimately blindness. XLRS primarily affects males and is typically diagnosed in early childhood. Approximately 30,000 males in the U.S. and EU have XLRS, for which there are currently no approved treatments.

About ATSN-201
ATSN-201 is Atsena’s investigational gene therapy leveraging AAV.SPR, a novel laterally spreading capsid designed to efficiently target photoreceptors in the central retina while avoiding the surgical risks of foveal detachment. ATSN-201 is the first XLRS gene therapy to demonstrate efficacy and positive safety data in a Phase 1 / 2 trial. The majority of patients in Part A of the trial demonstrated improvements in retinal structure (foveal schisis closure) and meaningful improvements in retinal and visual function as assessed by microperimetry, best-corrected visual acuity and low-luminance visual acuity. ATSN-201 has demonstrated a favorable safety profile and has been well-tolerated up to one year post-treatment. No serious adverse events have been reported. If approved, ATSN-201 will be the first gene therapy approved for XLRS. The first and best-in-class gene therapy product candidate has received Regenerative Medicine Advanced Therapy, Fast Track, Rare Pediatric Disease and Orphan Drug Designations from the U.S. Food and Drug Administration.

About AAV.SPR
AAV.SPR, one of Atsena’s novel capsids, spreads laterally beyond the subretinal injection site to enable safe and efficient transduction of the central retina (where schisis cavities predominate in XLRS patient retinas) when injected into areas outside the macula. A preclinical study in non-human primates demonstrated that AAV.SPR promotes transgene expression well beyond subretinal injection bleb margins. This is in contrast to benchmark AAV vectors, which remain confined to the original bleb margins. At clinically relevant doses, AAV.SPR efficiently transduces foveal cones without the need for surgical detachment and has a favorable safety profile relative to benchmark capsids. For more information about the preclinical study and how AAV.SPR works, visit https://atsenatx.com/our-approach/laterally-spreading-aav/.

About Atsena Therapeutics
Atsena Therapeutics (“Atsena”) is a clinical-stage gene therapy company developing best-in-class treatments for the reversal or prevention of blindness from inherited retinal diseases. The company’s lead program is evaluating ATSN-201 in an ongoing Phase 1 / 2 / 3 clinical trial for X-linked retinoschisis (XLRS), a genetic condition that is typically diagnosed in childhood and leads to blindness later in life. ATSN-101, Atsena’s first-in-class, investigational gene therapy for Leber congenital amaurosis type 1 (LCA1), has completed a Phase 1 / 2 trial with positive results (https://doi.org/10.1016/s0140-6736(24)01447-8). Atsena is advancing ATSN-101 toward the initiation of a global pivotal trial as part of its exclusive strategic collaboration with Nippon Shinyaku Co., Ltd. Atsena’s pipeline is powered by novel adeno-associated virus (AAV) technology tailored to overcome the hurdles presented by inherited retinal diseases. Founded by pioneers in ocular gene therapy, Atsena is led by an experienced team dedicated to addressing the needs of patients with vision loss. For more information, please visit https://atsenatx.com/.

Media Contact:
Gina Mangiaracina
6 Degrees
(917) 797-7904
[email protected]

Business Contact:
[email protected]