Gene therapy

The optimal solution for recessive retinal dystrophies.

The end goal of gene therapy is to provide diseased retinal cells with healthy DNA corresponding to a particular gene. To achieve this goal, HORAMA uses vectors, which penetrate the cells and transfer the healthy DNA into their nuclei (a process termed transduction). Once there, the healthy gene can then produce the normal protein it encodes. These vectors are generally viruses stripped of their infectious, viral activity (retrovirus, adenovirus, lentivirus).

HORAMA has made the choice to engineer such gene therapy vectors using recombinant-adeno-associated viruses (rAAV), which are the first-in-class vectors in the gene therapy race.

Our rAAV vector technology is aimed at a one-time administration to produce a therapeutic protein over the long-term.

Our target diseases, retinal dystrophies, are monogenic, progressively evolving pathologies. Many clinical trials over the past years, including the phase 1/2 clinical trial for Leber congenital amaurosis type 2 of HORAMA’s team, have shown the toxicological and immunological safety of rAAV technology.


Retina presents many advantages for gene therapy.

The retina is accessible by non-invasive subretinal injections i.e. between photoreceptors and retinal pigment epithelium (RPE).

The retina is small & enclosed, allowing the localised delivery of a relatively modest amount of gene therapy vector at or near the target site.

The retina is immuno-privileged due to the blood-retina barrier that prevents leakage of the administered vector to the systemic circulation. The blood-retina barrier limits the extent of vector dissemination outside of the eye and reduces the severity of potential immune responses to gene transfer vectors.

Moreover, the high stability of the targeted retinal cell populations and the lack of cell division allows the use of non-integrating vector systems such as rAAVs thus reducing the possibility of malignant transformation of the target cells (insertional mutagenesis and oncogenesis), which can arise from the insertion of the vector genome into the host cell genome.