Molecular photoswitch improves visual acuity in retinitis pigmentosa

Retinitis pigmentosa

Topline results from a Phase I/II clinical trial have shown that Kiora’s light-restoring small molecule KIO-301 has the potential to meaningfully improve vision in patients with retinitis pigmentosa (RP).

The results of the ABACUS study for Kiora’s intravitreal (IVT) molecular photoswitch were presented at the American Academy of Ophthalmology annual conference by Russell Van Gelder, Professor and Chair, Department of Ophthalmology, University of Washington, School of Medicine.

Although the study was not powered to primarily assess efficacy, the kinetic visual field (Goldmann perimetry) increased significantly from baseline at days seven and 14 post treatment.

There was a mean improvement in visual acuity of 0.30 logMAR (equivalent to three lines of visual acuity) in the high dose group, and light perception improved from baseline in patients with no or bare light perception.

Functional MRI demonstrated a qualitative increase in brain activity in the primary visual cortex at days two and 14 post-injection compared to baseline. KIO-301 was safe and well tolerated with no ocular and non-ocular serious adverse events, nor any signs of retinal inflammation.

“This new technology offers hope to patients living with late stage inherited retinal diseases. The mechanism of action and trial data firmly support KIO-301’s continued development, potentially filling a major unmet need in the search for treatments for these patients,” said Dr Van Gelder. “Based on shared pathology between RP and other inherited retinal diseases, we believe there is an opportunity to explore KIO-301 for several other indications including choroideremia and Stargardt’s disease.”

Conferring light-sensing capabilities

KIO-301 can potentially confer light-sensing capabilities to retinal neurons called retinal ganglion cells (RGCs). Once inside the cell, KIO-301 localises within specific voltage-gated ion channels involved in regulating neural signalling. When light hits these RGCs, KIO-301 alters its shape to change the flow of current, thereby activating the cell, and resulting in signalling the brain. When light is removed, KIO-301 reverts to its lower energy shape, stopping the signalling to the brain.

Dr Eric Daniels, Chief Development Officer of Kiora, said: “First-in-human studies are about safety and looking for signals of efficacy. In consultation with our scientific and medical advisors, data generated in this first-in-human study strongly support Kiora continuing to a sham-controlled, multi-dose Phase II clinical trial in 2024. We will share the results of ABACUS and design of ABACUS II with the US FDA in the fourth quarter to ensure alignment as we look to expand our clinical development into the US and EU.”

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