Promising Gene Therapy for PDE6b Retinitis Pigmentosa Shows Positive Phase I/II Data

Promising Gene Therapy for PDE6b Retinitis Pigmentosa Shows Positive Phase I/II Data

For individuals and families affected by inherited retinal diseases (IRDs), particularly those with retinitis pigmentosa (RP) caused by mutations in the PDE6b gene, news of advancements in gene therapy offers a beacon of hope. Coave Therapeutics recently announced positive 12-month results from its Phase I/II clinical trial of CTx-PDE6b, an innovative gene therapy designed to address this specific form of RP. This development is significant as there are currently no approved treatments for PDE6b RP, a condition that can lead to blindness by midlife.

Key Findings from the Trial

Coave Therapeutics reported that CTx-PDE6b demonstrated a good safety profile and clinically meaningful benefit in visual functions at the highest dose in patients with RP caused by bi-allelic mutations in PDE6b. The gene therapy, known as CTx-PDE6b (also referred to as HORA-PDE6b), is an AAV5-based treatment designed to deliver a full-length, non-mutated copy of the human PDE6b gene into the subretinal space. This aims to induce the synthesis of functional PDE6b protein in photoreceptive rod cells, with the goal of stabilizing or halting retinal degeneration.

The Phase I/II trial (NCT03328130) is a monocentric, open-label, dose-ranging study evaluating the safety and efficacy of CTx-PDE6b. Seventeen patients, aged 18 and above, with advanced PDE6b RP, completed the 12-month study period across three cohorts and two doses. A subgroup of six patients with less advanced disease who received the higher dose showed positive efficacy results across multiple clinical endpoints, including best-corrected visual acuity (BCVA), visual fields, microperimetry, full-field sensitivity test, and mobility test. Notably, microperimetry showed a significant favorable progression of sensitivity in the central retina of treated eyes compared to untreated eyes in this subgroup.

What This Means for Patients and Families

Retinitis Pigmentosa, particularly that caused by PDE6b mutations, is an inherited retinal dystrophy characterized by the progressive loss of photoreceptors, often leading to severe visual impairment and blindness. The positive 12-month data from this trial are encouraging, suggesting that CTx-PDE6b has the potential to make a real difference in the lives of those affected. The therapy aims to provide the missing functional protein, which is crucial for the process by which light is converted into electrical signals in the eye.

Coave Therapeutics has also received regulatory approval to expand the ongoing trial to include a new cohort of six younger patients, aged 13-25 years, with earlier stages of the disease. This expansion is significant because patients in earlier stages of the disease are expected to benefit most from gene therapy designed to preserve visual function. The first patient in this new cohort was expected to receive treatment by July 2023.

Looking Ahead

These positive results support Coave Therapeutics' preparations for a registrational trial for CTx-PDE6b in this indication. A registrational trial is a crucial step towards potentially seeking marketing approval from regulatory bodies. The continued development of CTx-PDE6b represents a hopeful step forward in the quest for effective treatments for PDE6b RP, offering the possibility of stabilizing or even halting the progression of this debilitating condition.