Atsena Therapeutics announced that dosing is complete in adults enrolled in Part B of LIGHTHOUSE, a phase 1/2/3 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, the company said in a press release. 

ATSN-201 leverages AAV.SPR, the company’s novel spreading capsid, to achieve therapeutic levels of gene expression in photoreceptors of the central retina while avoiding the surgical risks of foveal detachment. This gene therapy has received regenerative medicine advanced therapy, fast track, rare pediatric disease, and orphan drug designations from the US Food and Drug Administration (FDA). 

Part B of the ongoing multicenter clinical trial is evaluating a total of 9 adults and 3 pediatric patients with XLRS. Adults are separated into 3 groups: low volume, high volume, and control. Patients in the control group will be observed off-therapy for 1 year and then have the option to receive treatment.

In July 2025, the FDA agreed to expand the LIGHTHOUSE study to serve as a pivotal trial and support a biologics license application (BLA), which is anticipated in early 2028. RP