Hope in Sight: Emixustat Offers New Path for Stargardt Patients

CLERMONT-FERRAND, France & TOKYO, Japan – May 04, 2026 – For the thousands of people worldwide living with Stargardt disease, a rare genetic condition that progressively steals central vision from a young age, the words “no approved treatment” have long been a grim reality. Now, a glimmer of hope has emerged in France, as a new agreement paves the way for patients to access an investigational therapy, Emixustat, years before it might otherwise be available.

In a significant cross-border collaboration, Japanese drug developer Kubota Vision Inc. has partnered with French rare disease specialist Laboratoires KÔL. The deal allows for the distribution of Emixustat under France’s “compassionate use” authorization, a special regulatory pathway designed for severe conditions with no therapeutic alternatives. While not a full market approval, the move provides a crucial lifeline for patients and marks a pivotal step in the global fight against this debilitating disease.

Stargardt disease, affecting an estimated 1 in 8,000 to 10,000 people, typically begins in childhood or adolescence, causing a gradual decline in visual acuity that often leads to legal blindness. This agreement brings a potential first-line intervention to a community that has been waiting for decades.

Targeting the Source of Vision Loss

At the heart of Stargardt disease is a genetic flaw, most often in the ABCA4 gene. This mutation disrupts the retina's ability to clear waste products generated during the visual cycle—the complex process that converts light into neural signals. As a result, toxic vitamin A-derived metabolites accumulate in the retinal pigment epithelium (RPE), the supportive cell layer for the eye's light-sensing photoreceptors.

This toxic buildup leads to the death of RPE cells, which in turn causes the photoreceptors to die off, creating blind spots in the central field of vision. Emixustat, an oral medication, is designed to intervene directly in this destructive process through a mechanism known as visual cycle modulation.

Developed using Kubota Vision’s proprietary technology, Emixustat selectively inhibits RPE65, a key enzyme in the visual cycle. By slowing down this cycle, the therapy aims to reduce the rate at which toxic byproducts are formed, thereby protecting the RPE and photoreceptors from damage and potentially slowing the disease's progression.

Ryo Kubota, Chairman, President, and CEO of Kubota Pharmaceutical Holdings, stated, “We are extremely pleased to enter into this Agreement with Laboratoires KÔL for the development, supply and distribution of Emixustat for Stargardt disease (STGD1). By combining Kubota Vision’s clinical development and visual cycle modulation technology with KÔL’s expertise in rare ocular diseases, we aim to deliver meaningful impact for patients and the global ophthalmic community.”

A Strategic Pathway Through Compassionate Use

The partnership leverages the unique strengths of both companies: Kubota Vision’s innovative science and manufacturing capabilities, and Laboratoires KÔL’s deep expertise in navigating French regulatory pathways and distributing treatments for rare eye diseases. Under the agreement, Kubota will manufacture Emixustat, and KÔL will have exclusive rights to distribute it to eligible patients in France under the country’s early access program, overseen by the French National Agency for Medicines and Health Products Safety (ANSM).

This compassionate use pathway, known as Autorisation d'Accès Compassionnel (AAC) or Autorisation d'Accès Précoce (AAP), is a critical mechanism for patients with high unmet medical needs. It allows access to promising drugs that have demonstrated a favorable risk-benefit profile but have not yet completed the lengthy process for full market authorization.

“We are honored to collaborate with Kubota Vision to explore the development and commercialization of Emixustat for Stargardt disease, a condition that currently has no cure,” commented Sophie Momège, Founder and CEO of Laboratoires KÔL. “By combining our expertise with Kubota Vision’s proven clinical capabilities, we aim to bring one of the first effective treatments to patients worldwide and help reduce vision loss among children and adults.”

Navigating a Competitive and Complex Landscape

The journey of Emixustat highlights the challenging road of drug development for rare diseases. In August 2022, Kubota Vision announced that its 194-patient Phase 3 clinical trial, known as SeaSTAR, did not meet its primary endpoint of reducing the rate of macular atrophy progression across the entire study population.

However, a subsequent post-hoc analysis revealed a potentially significant finding: in a subgroup of patients with smaller atrophic lesions at the start of the trial, Emixustat showed a 40.8% reduction in lesion progression compared to placebo over 24 months. This suggests the drug may be most effective in the earlier stages of the disease, a hypothesis that likely underpins the decision to pursue compassionate access while further development strategies are evaluated.

The field of Stargardt treatment is becoming increasingly competitive, with several other companies making significant strides. Alkeus Pharmaceuticals' Gildeuretinol (ALK-001), a modified form of vitamin A, has shown in clinical trials that it can halt disease progression in early-stage patients. Similarly, Belite Bio's Tinlarebant (LBS-008), an oral therapy that reduces vitamin A transport to the eye, met its primary endpoint in a Phase 3 trial by significantly slowing lesion growth.

Alongside these small molecules, multiple gene therapies are also advancing through clinical trials, aiming to correct the underlying genetic defect. This crowded and fast-moving landscape underscores the urgency and investment being poured into solving Stargardt disease. For patients in France, the Kubota and KÔL agreement means they will not have to wait on the sidelines as these scientific races unfold, providing them with a tangible option and a powerful dose of hope.