XLRS is a monogenic X-linked disorder caused by RS1 gene mutations, resulting in declining visual acuity and blindness. Credit: Mangza2029 / Shutterstock.com.

Atsena Therapeutics is set to proceed with the pivotal Part C cohort of its Phase I/II/III LIGHTHOUSE trial of ATSN-201 in patients with X-linked retinoschisis (XLRS), following the recommendation from the independent data monitoring committee (DMC).

The DMC’s recommendation comes after a review of accumulated safety and efficacy data from earlier parts of the study for this XLRS gene therapy trial.

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Atsena Therapeutics will begin screening for Part C of the trial this month.

Part C of the LIGHTHOUSE trial is the pivotal Phase III section and aims to enrol 76 patients with XLRS across major clinical sites in Europe and North America.

Participants will be assigned to either treatment or control groups; those in the treatment arm will receive bilateral or unilateral ATSN-201 treatment, while the control group will be observed for 12 months before administering the therapy.

Screening is planned to begin this month, with enrolment completion expected by the end of the first quarter of 2027. Phase III cohort data are expected to support a biologics licence application submission in 2028.

XLRS is a monogenic X-linked disorder caused by mutations in the RS1 gene, leading to improper retinal layer splitting, declining visual acuity, and eventual blindness.

The investigational product, ATSN-201, uses the company’s AAV.SPR capsid to target central retinal photoreceptors without requiring foveal detachment.

Early trial data indicate ATSN-201 has shown a favourable safety profile and improvement in retinal structure and function, as measured by imaging and vision tests.

Regulatory designations have been granted in the US and Europe, and the study remains ongoing.

Atsena Therapeutics chief medical officer Kenji Fujita said: “We are excited that the DMC has recommended that we proceed with the pivotal Part C cohort. 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.”

In May 2024, Atsena Therapeutics announced positive preliminary data for its gene therapy candidate ATSN-201 for XLRS.