Initial tests are done on cellular or animal models to establish “Proof of principle” If these test are successful then funding and authorization for a human clinical trial is sought.
Clinical trials are registered with a government agency – FDA in America, EMA in Europe and the Department of Health in South Africa.
Clinical trials are usually conducted in three phases with rigorous control and review at every stage. Trials can only progress to the next phase when all data and safety information has been reviewed by a board.
This is usually a small group of patients who live in close proximity to the clinic conducting the trial. The primary outcome is usually safety only. If there are no adverse events, permission will then be granted to go onto the next phase.
This involves more patients and safety, dosage and effectiveness is studied. This will typically be fewer than 50 patients, but varies tremendously. Again, once all data has been assessed, then permission is given for the next phase.
These often go to multicentre trials as in IRD the number of patients at a single clinic may not be sufficient to achieve the required results.
The endpoint of a Phase 3 trial is usually effectiveness prior to registration
A Clinical trial is not a cure.
Many IRD are considered as Orphan [ rare ] diseases and are often given special priority and dispensations.
The estimated incidence of IRD are:
- AMD [65+ age group]
- 25% Caucasians, 15% Coloured, 10% Indian/ Asian, 1% Black African
- Retinitis Pigmentosa [1 / 3000]
- Stargardt Dystrophy [1/ 8 000]
- Leber Congenital Amaurosis [3 / 100 000]
- Usher Syndrome – Type 1[1 / 12000], Type 2 [ 1 / 25 000]