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July, 09 2025 • Articles

Atsena Therapeutics Releases XLRS Community Statement

This morning, Atsena issued a press release to announce that they have achieved alignment with the FDA on a regulatory pathway for ATSN-201 in X-linked retinoschisis (XLRS). Atsena is pleased that the FDA has agreed to their proposal to expand our Phase 1/2 gene therapy trial into a continuous Phase 1/2/3 trial.

How do clinical trials usually work — and what is different about a continuous Phase 1/2/3 trial?

Typically, new treatments go through three separate phases of clinical trials before they can be approved:

• Phase 1 tests safety in a small group of people.

• Phase 2 looks at whether the treatment works, usually in a slightly larger group.

• Phase 3 confirms those results in an even bigger group to make sure the treatment is effective and safe.

Each phase usually happens one after the other, and it can take many years to complete all three.

But in rare diseases, researchers are sometimes able to combine several phases. They may propose using a "continuous Phase 1/2/3 trial" — one continuous study that includes all three phases in a single trial. Instead of starting and stopping between phases, the trial is designed to move smoothly through each stage as more information becomes available. This approach can save time and help bring potential treatments to patients more quickly.

What does this mean for the timing of Atsena’s XLRS clinical trial?

Atsena believes that converting their existing Phase 1/2 clinical trial into a continuous Phase 1/2/3 trial speeds up the overall development timeline by about 18 months compared to the traditional process of conducting a separate Phase 3 trial. This means that they may be able to submit an application to the FDA for potential approval of the gene therapy for broad use as early as 2028.

What is the current status of Atsena’s XLRS clinical trial?

Atsena has completed the “Phase 1” portion of the trial and is currently recruiting adult participants (age 18+) for the “Phase 2” portion. They will recruit several pediatric participants (ages 6-17) after obtaining additional safety and efficacy data in adults from the “Phase 2” portion of the clinical trial.