Company: BLTE
Filing Date: 2025-12-02
Form Type: 424B5
Source: 0001104659-25-117702
Chunk: 41

Company: BELITE BIO, INC
Filing Date: 2025-12-02
Form: 424B5
Chunk 41
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 toxic vitamin A by-products and cellular debris which precedes the death of retinal tissue and loss of vision. STGD1 is the most common inherited retinal dystrophy, with an average prevalence rate of approximately 1:8,800 based on a weighted population proportion calculation. The estimated patient population is approximately 53,000 in the United States and approximately 109,000 in China. The disease is typically diagnosed at a young age, often starting during childhood or adolescence, and is characterized by lesions within retinal tissue which cause severe and irreversible loss of visual acuity gradually leading to legally defined blindness at a very young age. Older age at onset (>20 years of age) is associated with slower disease progression. There are no FDA-approved treatments for STGD1.

Individuals affected with STGD1 harbor mutations in a retina-specific ATP-binding cassette, or ABC, transporter gene, known as ABCA4 . The ABCA4 gene encodes an ATP-dependent transporter, known as ABCA4, or Rim Protein. This protein resides at the rim of rod and cone photoreceptor disc membranes where it removes light-activated or ‘bleached’ visual chromophore (all-trans retinal) from the retina permitting detoxification by a retinal dehydrogenase (RDH8) which, in turn, allows recycling within the underlying RPE. The primary function of the RPE is to provide metabolic and trophic support to sustain health and integrity of the retina. The intimate association of the RPE with outer segments of rod and cone photoreceptors facilitates this function.

The RPE converts dietary vitamin A delivered from the blood circulation, and recycled retinol liberated from the retina following exposure to light, into visual chromophore (11-cis retinal). The visual chromophore is then transferred to the retina to maintain light sensitivity and function of the retina. The enzymatic conversion of dietary vitamin A to a light-sensitive visual chromophore is a unique process which only occurs within RPE cells and the ABCA4 protein plays a key role in this process—see figure below.

The processing of vitamin A (aka, retinol, or all-trans retinol) in the visual cycle begins with the delivery of circulating retinol to the RPE. The ternary complex of RBP4-retinol-TTR is presented to RBP4 receptors which are located on the basal surface of RPE. The RBP4-TTR vehicle serves to solubilize retinol and produce a