A phase 3 trial of Belite Bio’s tinlarebant in adolescents with a rare genetic eye disease has met its primary endpoint, encouraging the biotech to add the U.S. to the list of countries in which it plans to file for approval next year.
The trial randomized 104 people with Stargardt disease type 1 (STGD1) to receive tinlarebant or placebo. People with the disease develop lesions in their eyes and experience loss of central vision. Tinlarebant, an oral drug candidate, is designed to reduce the accumulation of the vitamin A-based toxins that drive STGD1.
Belite linked tinlarebant to a 35.7% reduction in lesion growth rate versus placebo, achieving the study’s primary endpoint. A post hoc analysis intended to account for the progressive nature of STGD1 yielded a similar result, as did other measures of lesion growth.
The biotech saw minimal change in visual acuity after 24 months in either group. Belite said the vision result was expected. Quan Dong Nguyen, M.D., professor of ophthalmology at the Byers Eye Institute at Stanford, said in a statement that “it is only a matter of time before the observed reduction in lesion growth translates into measurable benefits in visual function.”
There were four treatment-related drug discontinuations. Xanthopsia—a color vision deficiency—and delayed dark adaptation were the most common drug-related ocular adverse events. Belite said most of those adverse events were mild and resolved during the study. Headaches were the most commonly reported treatment-related non-ocular adverse event.
Belite plans to seek FDA approval in the first half of next year. The plan sees the U.S. join China and the U.K. on the list of countries where Belite is preparing to seek approval. Regulators in China and the U.K. agreed to accept authorization filings after the data safety monitoring board reviewed interim data in February. The board recommended that Belite seek approval after the interim analysis.
Shares in Belite rose nearly 18% in premarket trading. The jump reflects the potential for Belite to be the first company to launch a treatment for STGD1 in the U.S. Multiple companies are developing drugs to treat Stargardt, with Ocugen’s phase 2/3 gene therapy OCU410ST among the most advanced candidates. But Belite is on course to be first to market in the U.S.
The hit in the STGD1 trial could also be an encouraging sign for Belite’s plans to develop tinlarebant in patients with geographic atrophy (GA). Astellas’ Izervay and Apellis Pharmaceuticals’ Syfovre are FDA approved in GA but are administered as intravitreal injections. Tinlarebant could give patients an oral treatment option. Belite is running a phase 3 trial in GA.