Myosin 7A (MYO7A) is the gene involved in USH1B, the most common form of USH type 1.
In Paris (Hopital Nationale des Quinze-Vingt, France) and Portland (Casey Eye Institute, Portland, Oregon, USA), researchers have in cooperation with the pharmaceutical company Sanofi been busy for some time conducting a study with patients (clinical trial) into the safety and effectiveness of gene therapy for USH1B. The trial study is called @UshStat and focuses on delivering the normal MYO7A gene with one single surgical injection below the retina. In this study no use is made of the AAV vector but of a Lentiviral vector, called EIAV. Contrary to an AAV vector, a lentiviral vector has sufficient capacity to deliver the entire MYO7A gene.In phases 1 and 2 of clinical trials the safety and the effectiveness are tested with a small number of persons. The main objective of the study is to find out whether the therapy does not have any side effects and is safe for use on patients. The phase 1/2 clinical studies for @UshStat have already been started. The test persons treated in this study suffer from really serious retinal degeneration caused by mutations in the MYO7A gene, USH1B. Only 1 eye is treated during the trial in order to be able to compare the effect of the treatment with the untreated eye of the patient. The first test with a low dose appeared to be safe. When applying a higher dose, 1 of the 9 test persons developed pan-uveitis, an infection in the vitreous of the injected eye. This patient was treated for the developed infection and fully recovered. All treated test persons were followed for 150 days after the treatment. An improved sharpness of vision in the treated eyes was recorded. Some test persons also showed some differences in the size of their fields of vision.
The serious infection as a possible side effect of the treatment made the Independent Safety Committee in France decide to pause the 1/2 trial.
The trial was stopped for a year and this year was used to increase the safety of the treatment. The researchers received approval to resume the trial @UshStat (MYO7A gene replacement therapy) late 2018/early 2019.

However, the pharmaceutical company Sanofi has decided not to continue this study and wants to sell the licenses. The @UshStat trial study (SAR 421869) is now pending a new pharmaceutical company that wants to buy the licenses and restart the trial. (July 2019 update).

There is a second study that tracks the long-term effects of those who participated in the discontinued phase 1/2 SAR421869 trial.