Biogen’s rare eye disease gene therapy falls short at Phase III
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Biogen’s rare eye disease gene therapy falls short at Phase III

By Kezia Parkins 15 Jun 2021

Biogen's late-stage study evaluating timrepigene emparvovec to treat choroideremia has failed to hit its main goals.

Biogen’s rare eye disease gene therapy falls short at Phase III
Biogen’s Phase III STAR study of its gene therapy for the rare inherited eye disease choroideremia failed to meet its primary and key secondary endpoints. Image Credit: Shutterstock

Biogen’s Phase III trial of its gene therapy, timrepigene emparvovec, did not meet its primary or key secondary endpoints in patients with the rare inherited eye disease choroideremia, the firm has announced.

The Phase III STAR study, a multicenter, randomized, three-arm, parallel-controlled group trial, evaluated the safety and efficacy of a single subretinal injection of the investigational gene therapy. It enrolled 169 adult males with a genetically confirmed diagnosis of choroideremia, a rare inherited retinal disease that results in progressive vision loss and eventually leads to blindness.

Timrepigene emparvovec is an investigational recombinant AAV2 vector ‘designed to deliver a functional version of the human choroideremia gene into the retinal pigment epithelium and photoreceptor cells that aims to address the underlying genetic cause of choroideremia’.

The primary endpoint of the study was the proportion of patients with an improvement of at least 15 letters from baseline in best-corrected visual acuity (BCVA) at 12 months post-treatment, as measured by the Early Treatment Diabetic Retinopathy Study (ETDRS) chart.

The study failed to meet this primary endpoint and saw that the gene therapy did not increase the number of patients demonstrating an improvement on this measure.

Additionally, the Phase III STAR study did not demonstrate efficacy on key secondary endpoints, although the safety results were consistent with earlier studies evaluating timrepigene emparvovec.

“We extend our deepest gratitude to all those who contributed to the STAR study, including the participants, investigators, site staff, and the broader choroideremia community,” said Biogen Therapeutics Development Unit head Katherine Dawson.

“While we are disappointed by the results of the STAR study, we are hopeful that the clinical insights gleaned from this study may help to shape therapeutic innovation for inherited retinal diseases including choroideremia, so that in the future there may be treatment options for the community affected by these debilitating disorders.”

Biogen said it will evaluate the complete data set before confirming next steps for the timrepigene emparvovec clinical development program. Detailed results of the study will be made available at a future scientific forum.