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Amicus Therapeutics has announced the discontinuation of its investigational AT-GTX-501 gene therapy program for late childhood neuronal ceroid lipofuscinosis, also known as CLN6 Batten disease.

The company is, however, advancing its gene therapy program for juvenile Batten disease, also known as CLN3 disease, according to a press release.

The decision to discontinue its CLN6 gene therapy program was based on data from a long-term follow-up study (NCT04273243) of CLN6 Batten patients, ages one year and older, which showed that AT-GTX -501 failed to stabilize disease progression.

Patients were enrolled in the long-term follow-up (extension) study after completing a Phase 1/2 clinical trial (NCT02725580) where they received a single injection of AT-GTX-501 into the spinal canal ( intrathecal).

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Interim data collected two years after injection showed that gene therapy stabilized motor and language functions.

Now, the company reports that the following extension study found that this stabilizing effect was not sustained beyond two years.

Amicus will perform further analysis and plan data sharing with key stakeholders in the CLN6 community.

AT-GTX-501 provides a working version of the CLN6 gene, which is mutated in people with the disease. This causes toxic deposits called lipofuscins to build up, especially in cells of the central nervous system (brain and spinal cord).

Gene therapy uses an adeno-associated virus (AAV), a common naturally occurring virus, which has been shown to be effective as a gene therapy delivery vehicle. The virus is modified in the laboratory so that it does not cause disease.

Amicus has another gene therapy program for juvenile Batten disease. The company plans to move the program forward, but with some adjustments, pending new data from the ongoing Phase 1/2 trial (NCT03770572) testing AT-GTX-502 in infants and children, aged 3 to 10 years old, with juvenile Batten disease and new preclinical studies. The data. These data are expected this year.

In this trial, the therapy is given by injection directly into the patient’s cerebrospinal fluid (intrathecal injection), to ensure that it reaches the cells of the central nervous system. Early results showed that gene therapy was well tolerated and had the potential to stabilize early signs of the disease in children and infants.

The new tweaks include using a higher dose, a different promoter (an element that acts like a switch to turn genes on), and a different route of administration – namely, directly into the brain in cerebrospinal fluid (CSF), the fluid surrounding the brain and spinal cord.

AT-GTX-502 uses an AAV, called AAV9, to provide a working copy of CLN3 — the defective gene in CLN3 disease — to patients’ nerve cells. Therapy should slow the physical and neurodevelopmental decline that characterizes the disease.

“We see further opportunities to impact the lives of people with rare diseases through our genetic medicine business and capabilities,” said John F. Crowley, Amicus President and CEO. “Amicus is in a stronger position than ever and we remain true to our mission to transform the lives of people living with rare and life-threatening diseases.”