Eye On the Cure Research News

May 14, 2021

Biogen’s Phase 2/3 Clinical Trial for XLRP Gene Therapy Doesn’t Meet Primary Endpoint

More details from the clinical trial will be reported at a later date

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Biogen, a global biotech therapy developer, has announced that XIRIUS, a Phase 2/3 clinical trial for an X-linked retinitis pigmentosa (XLRP) gene therapy, did not meet its primary endpoint — improvement in central retinal sensitivity as measured by microperimetry. The company did report that it was encouraged by positive trends in other clinically relevant endpoints, such as a measure of visual acuity under low light conditions. Data from the trial were assessed at 12-months after dosing.

Complete analysis of the XIRIUS study is ongoing. The company will report detailed results at a future scientific forum and will communicate next steps for the program at a later date.

Biogen’s emerging XLRP gene therapy is for people with mutations in the gene RPGR. The therapy is designed to deliver normal copies of RPGR to replace the patient’s mutated copies. The RPGR copies are delivered using a human-engineered adeno-associated virufighs (AAV), which works like a vast container system to penetrate retinal cells with the therapeutic, genetic cargo. The gene therapy is contained in a tiny drop of liquid which is injected underneath the retina.

XLRP affects approximately 20,000 people in the US and EU. The condition causes constriction of vision, reduced vision in dark settings, and central vision loss, especially in later stages. Most people with XLRP are legally blind by the age of 45. XLRP primarily affects men. While women are XLRP carriers and usually unaffected, they can have vision loss, as well.