Recently, biopharmaceutical company GenSight Biologics (“GenSight”) announced the publication of data from a study evaluating GS030-Drug Products (GS030-DP or “GS030”) as a potential treatment option for retinitis pigmentosa (RP). Although the study was centered around the drug in non-human primates (NHP), GS030 fits into GenSight’s overall mission of developing gene therapy solutions for central nervous system (CNS) or retinal neurodegenerative conditions. Read the full study, discussing optogenetics in NHP, in Communications Biology.
GS030
GenSight uses a specialized optogenetics platform, leveraged by GS030 to treat retinal neurodegeneration. According to Nature:
Optogenetics is a method that uses light to modulate molecular events in a targeted manner in living cells or organisms. It relies on the use of genetically-encoded proteins that change conformation in the presence of light to alter cell behaviour, for example, by changing the membrane voltage potential of excitable cells.
Basically, researchers transfer a gene to patients, which encodes for a specific light-sensitive protein. This prompts cells to respond to light stimulation which, in turn, allows patients to regain some vision or visual capabilities. In this case, GS030 uses optogenetics to provide this gene into retinal ganglion cells, which later become photosensitive cells. Patients wear a set of goggles which allow the retina to be treated directly. Interestingly, GS030 would not be siloed to only treat Retinitis Pigmentosa. In fact, it could also be used for other neurodegenerative retinal conditions, offering a more comprehensive and accessible treatment option for patients.
The Research
Within the recently published research, GenSight offered proof-of-concept data regarding optogenetics, GS030, and retinal ganglion cell improvement in NHPs. By using the treatment, researchers improved vision, allowing NHPs to see above the level of legal blindness. GenSight used this data for their Investigational New Drug (IND) application, which has been approved. Now, GenSight will be able to perform the Phase 1/2 PIONEER trial to analyze the safety, efficacy, and tolerability of GS030 for human patients with Retinitis Pigmentosa. Data should be available by the middle of 2021. Additional findings from the proof-of-concept study include:
- Injecting the gene and therapy into the retina did not cause a severe injection response, a poor immune reaction, or inflammation in or around the eye.
- Using a modified viral vector worked better than using a wild-type vector.
- The ideal therapeutic dose is 5 × 1011 vg/eye. However, considering the use of NHPs, this dose will need to be studied again in human-oriented clinical trials.
- After treatment, NHPs were able to distinguish between specific patterns of shapes, showing that their vision was higher than the level of legal blindness. Legal blindness is typically considered to be 20/400.
Retinitis Pigmentosa (RP)
Retinitis Pigmentosa (RP) refers to a group of inherited conditions which cause retinal degeneration. The retina, a thin tissue of tissue in the back of the eye, helps us see. As light passes through the retina, the retina converts the light into electrical signals; the brain later uses this to see what is in front of us. More than 60 gene mutations are associated with RP, with over 20 of these mutations associated with the autosomal dominant form. RHO gene mutations cause up to 30% of autosomal dominant cases. Forms of RP include Bardet-Biedl syndrome and Leber congenital amaurosis. As photoreceptor cells in the retina degenerate, RP causes progressive vision loss. In many cases, patients with RP become legally blind before or by 40 years old. An estimated 1.5 million people globally have RP. Symptoms include:
- Night blindness
- Inability to perceive colors or details
- Decreased central vision
- Tunnel vision
- Difficulty driving, reading, or recognizing faces or objects
- Sensitivity to bright lights
