AVR-RD-01 is an investigational lentiviral-based gene therapy developed by AVROBIO to treat Fabry disease.

How AVR-RD-01 works

Fabry disease is a rare genetic condition caused by a mutation in the GLA gene, which results in the deficiency of an enzyme called alpha-galactosidase A. The lack or reduced activity of the enzyme causes a fatty substance called globotriaosylceramide (Gb3 or GL-3) to build inside cells, leading to irreversible organ damage.

AVR-RD-01 is a gene delivery system using a harmless virus that inserts the nonmutated form of the GLA gene containing information for making functional alpha-galactosidase A into the body.

For the treatment, adult stem cells in the blood (hematopoietic stem cells) are isolated from the patient and exposed to the lentiviral vector, or modified virus. The virus inserts the gene into the stem cells, which are then returned to the patient’s body. Because secreted alpha-galactosidase A by modified blood stem cells is taken up by other cells in the vicinity, this therapy potentially restores alpha-galactosidase A levels to normal ranges throughout the body.

AVR-RD-01 in clinical trials

AVR-RD-01 is currently being tested in two separate clinical trials that are still recruiting patients.

The first (NCT02800070) is a Phase 1 study in Canada aimed at determining whether AVR-RD-01 can safely increase alpha-galactosidase A levels in Farby patients. A six-month follow-up of the first patient to receive this therapy showed consistent and normal levels of alpha-galactosidase A starting at 45 days after treatment with no negative side effects. The study’s enrollment is estimated at six participants.

The second trial (NCT03454893) is a multinational Phase 1/2 study assessing the effectiveness and safety of AVR-RD-01 in patients with Fabry disease who have not received any other treatments. It is being conducted in Australia with the first results expected in 2020. The preparation, treatment, and initial follow-up process is expected to take about one year, after which patients will be monitored regularly. Enrollment is estimated at 12 participants.

Further information

Enzyme replacement therapy is the current standard of care for Fabry disease, requiring lifelong weekly infusions. AVR-RD-01 offers a potentially permanent cure for the disease with only one infusion.

Although AVR-RD-01 trials have not reported any side effects yet, gene therapy has some potential risks that can only be revealed in time. Some of these are toxicity, inflammation, and cancer.

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