Endogena Therapeutics Doses First Patient With Novel Treatment For All Retinitis Pigmentosa Types

Retinitis pigmentosa (RP) is a group of inherited diseases affecting 1 in 3,000-7,000 people, causing slow and progressive retinal degeneration, which finally can lead to the full loss of vision. “Inherited” hints that RP is caused by defective genes, which can have one of three inheritence patterns. The most common one is autosomal dominant, when one copy of an altered gene is enough to cause the disorder. The autosomal recessive inheritance is characterized by the pattern in which two gene copies should carry the mutation for the RP phenotype. Last, but not the least, in the X-linked inheritance the mutated gene is located on the X-chromosome, hence all men with the mutated gene will develop RP; females usually need two defective gene copies to develop RP, but around 20% have clinical symptoms even with one alteration.There are few other inheritance patterns described for RP, but they are comparatively rare. 

So far, there are more than 80 genes identified, alterations in which lead to syndromic and non-syndromic RP, indicating the considerable level of disease heterogeneity. The function of these mutated genes involve phototransduction, photoreceptor development, retinal homeostasis and many more.

Considering that the genetic mechanisms for the majority of RP types were discovered, it became the central strategy in building the therapeutic approaches to fight the disease. Firstly, when the altered gene is identified, gene therapy can be applied to deliver a correct copy of the gene directly to the retina cells, usually using viral vectors (“carriers”). This approach was used for — the first FDA-approved gene therapy for RP. Patients can be treated with Luxturna if they have autosomal recessive mutations in , the gene which codes the essential protein in the visual cycle of the retina. The approval of Luxturna induced an intensive research in the direction of gene therapy for RP, resulting in multiple other candidates entering the clinical trials.