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Chemistry: Generation 2.5

ION357 (formerly IONIS-RHO-2.5Rx), also known as QR-1123, is an investigational antisense medicine drug designed to selectively reduce the production of the rhodopsin P23H mutant protein in the eye while allowing normal protein to be expressed. The allele-selective targeting of the ASO to the single-base P23H mutation prevents degeneration of rod photoreceptor cells and preserves cone photoreceptor cell function. ION357 provides a novel approach to treating autosomal dominant retinitis pigmentosa, in which patients have limited therapeutic options.

About Retinitis Pigmentosa

Retinitis pigmentosa (RP) is a group of rare inherited eye disorders causing photoreceptor degeneration that leads to progressive vision loss. The disease is clinically and genetically heterogeneous and can have an autosomal recessive, autosomaldominant, or X-linked pattern of inheritance. Affected patients first experience defective dark adaptation during adolescence or young adulthood, followed by loss of peripheral visual field when rod photoreceptor function declines. Patients eventually have only a residual central island of vision, which ultimately leads to complete blindness around the age of sixty.