Gene therapy for ophthalmic disorders

Gene therapy is the process of modifying a patient’s cells by adding a functional copy of the mutated gene responsible for the disease. The new functional copy allows a patient’s own body to produce proteins to treat or prevent genetic conditions. A single treatment can provide long lasting benefits, potentially leading to a better quality of life.

Gene therapy has a growing research potential in the field of retinal diseases owing to three main characteristics of the eye. First, it is easily accessible for treatment via injections and surgical interventions. Second, its immune-privileged status means the eye can accommodate the antigenicity of a viral vector, and third, the tight blood-ocular barrier prevents other organs from unwanted contamination.

Pipeline

Beacon Therapeutics has a broad ophthalmic development pipeline of differentiated assets including a late-stage development candidate, AGTC-501, to treat X-linked retinitis pigmentosa (XLRP), as well as two preclinical programs one targeting dry age-related macular degeneration (dry AMD) and another spun out from the University of Oxford targeting cone-rod dystrophy (CRD), an inherited retinal disease.

AGTC-501

Lead development candidate, AGTC-501, is a gene therapy program currently in Phase 2 clinical trials for the treatment of XLRP, an inherited monogenic recessive disorder that causes progressive vision loss in boys and young men. XLRP is predominantly caused by mutations in the RPGR gene. AGTC-501 correctly
expresses the full length RPGR protein, thereby addressing the full complement of photoreceptor damage caused by XLRP, including both rod and cone loss.

Preclinical stage asset for dry AMD

Beacon Therapeutics is developing an intravitreally (IVT) delivered novel adeno-associated viruses (AAV) based program for dry AMD. Dry AMD is a leading cause of irreversible vision loss in people over 60, if left untreated. Around 20 million people in the United States suffer from AMD.

Preclinical stage asset for CRD

Null mutations in the Cadherin Related Family Member 1 (CDHR1) gene can cause cone-rod dystrophy (CRD). As a monogenic recessive disorder, Beacon Therapeutics’ gene therapy could be the ideal platform to address this currently underserved patient population. Professor Robert MacLaren, Professor of Ophthalmology at the University of Oxford, a retinal expert and an experienced biotech company founder, is an active advisor on Beacon’s CDHR1 program and is also a Co-Founder of Beacon Therapeutics.

Target generation technology platform

Beacon Therapeutics has access to a target generation technology platform that will identify, screen and search secreted proteins in the ophthalmology space.

Retinal diseases

The retina is the layer at the back of your eyeball which contains light-sensitive cells. It converts light that enters into your eye into electrical signals that your optic nerve sends to your brain which, in turn creates the images you see. It’s a key part of your vision. Retinal diseases can either be inherited or can be caused by aging.

X-linked retinitis pigmentosa (XLRP)

Retinitis pigmentosa (RP) describes a group of rare genetic eye diseases that damage light-sensitive cells in the retina, leading to loss of sight over time. In about 10% of RP cases, the non-working gene is passed down from the mother to her children resulting in a form of RP known as XLRP.

XLRP causes gradual vision loss in boys and young men. The disease begins with night blindness and is followed by a slow narrowing of the peripheral field of vision. In general, the decline in vision (also referred to as “visual acuity”) results in a person becoming legally blind in their 40s.

Further information about how RP is inherited and the impact on the vision of male and female children can be found here.

Dry AMD

Age-related macular degeneration (AMD) is a retinal disease that can blur your central vision. It occurs when aging causes damage to the macula, the part of the eye that controls sharp, straight-ahead vision.

Dry AMD is a slow deterioration of the cells of the macula, often over many years, as the retinal cells die off and are not replaced.
The progression of dry AMD varies but can take a long time so many suffering with the condition do not immediately seek medical help and diagnosis can therefore be delayed.

Further information on the symptoms and causes of age-related macular degeneration (AMD) can be found here.

Cone-rod dystrophy (CRD)

Cone-rod dystrophy (CRD) is a group of inherited eye disorders that affect the light sensitive cells of the retina called the cones and rods. There are over 30 types of CRD caused by genetic changes in several different genes that can be inherited in many ways including autosomal recessive, autosomal dominant, X-linked or mitochondrial patterns. Beacon Therapeutics is working on null mutations in the Cadherin Related Family Member 1 (CDHR1 gene), which may cause cone-rod dystrophy in younger patients, resulting in severe sight loss. In adults, a recently characterised mutation that reduces CDHR1 function also leads to a macular dystrophy in older people that is very similar to dry AMD.

People with CRD experience vision loss over time as the cones and rods deteriorate. Initial signs and symptoms that usually occur in childhood may include decreased sharpness of vision (visual acuity) and abnormal sensitivity to light (photophobia). These signs are usually followed by blind spots in the central field of vision (scotomas), loss of color perception, and loss of peripheral vision. Most individuals with this condition are legally blind by mid adulthood.

Further information on the symptoms and causes of CRD can be found here.