Globally 4.5 million people are affected by IRDs — a group of diseases having a broad clinical spectrum — that damage the retina. The main characteristics of IRDs are the loss or dysfunction of photoreceptors, and patients with IRDs can experience severe vision loss or even blindness.
As mentioned in the article Updating the Genetic Landscape of Inherited Retinal Dystrophies published in July 2021, there were over 270 different genes linked to IRDs.
Despite the challenges stemming from this high genetic and clinical heterogeneity, Gene Therapy treatments have significant potential for treating retinal conditions, and scientists are working toward their development.
Factors driving progress in Gene Therapy treatments for Inherited Retinal Disorders.
Gene therapies for retinal disorders have made significant progress thanks to the advancements in cell-specific targeting and the high transduction efficiency achieved by AAVs.
Moreover, the eye has the following three main characteristics that make it an appropriate gene therapy target which is not susceptible to drug side effects. More specifically, the eye:
- is easily accessible
- has the ability to tolerate antigens
- has tight blood-ocular barriers
Inherited Retinal Disorders classification brings us closer to effective Gene Therapy treatments.
IRDs classification enables better disease prognosis and ensures effective disease management.
Genetic testing is necessary to identify the causative mutation because scientists have identified more than 300 IRDs (as of May 2022).
Photoreceptor disorders, macular dystrophies, and choroidal dystrophies are three major classes of IRDs that are already classified.
The table below shows a few disorders per class (the list is not exhaustive), as discussed in the “Gene Therapy for Inherited Retinal Disease” article.
| Class | Diseases (not exhaustive list) |
| Photoreceptor disorders | Retinitis pigmentosa, Leber congenital amaurosis |
| Macular dystrophies | Stargardt disease, X-linked retinoschisis, |
| Choroidal dystrophies | Choroideremia |
Table 1: IRD classes and diseases (information from Gene Therapy for Inherited Retinal Disease ,Review of Ophthalmology)
Promising landscape for Gene Therapy for Inherited Retinal Disorders
Luxturna by Spark Therapeutics is the first and only FDA-approved (2017) gene therapy for Inherited Retinal Disorders due to mutations in the RPE65 gene, which are responsible for Retinitis pigmentosa and Leber congenital amaurosis (LCA).
Gene Therapy treatments for different IRD s underway. Clinical trials’ data as of May 2022 showed 47 trials that were recruiting, 25 beginning soon, and 72 that had been completed.
Companies such as Allergan / Editas Medicine (NCT03872479), Biogen (NCT03507686), Spark Therapeutics (NCT02341807), Sanofi (NCT01736592), and Janssen (NCT04671433) are major players in this space.
While the treatment landscape is promising, it is still challenging. The path forward largely depends upon strategic aspects to commercialize the treatment options.
Gene Therapy Treatments for Inherited Retinal Diseases. Addressing the Challenges
The first step would be to raise awareness within the entire ecosystem, including patients, physicians, carers, and payers, about genetic testing and the available treatment options. Leveraging patient organizations and creating a social media buzz would be a good starting point for the companies.
Then the companies in the Gene Therapy space should set up teams dedicated to networking with centers certified in gene therapy administration.
Finally, there is a need for innovative reimbursement strategies to create strong payer traction.
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#IRDs #InheritedRetinalDystrophy #GeneTherapy #retinitispigmentosa #Luxturna #SparkTherapeutics #GeneTherapyTrials #Ophthalmology #ClinicalResearch #Biogen #Sanofi #Janssen
Sources:
Updating the Genetic Landscape of Inherited Retinal Dystrophies
Gene Therapy for Inherited Retinal Disease
Gene therapy in retinal diseases: A review : Indian Journal of Ophthalmology
https://classic.clinicaltrials.gov/ct2/show/NCT03872479
https://classic.clinicaltrials.gov/ct2/show/NCT03507686
https://classic.clinicaltrials.gov/ct2/show/NCT02341807
https://classic.clinicaltrials.gov/ct2/show/NCT01736592
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8421966/
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