28 September 2020 - - The European Commission has granted orphan drug designation for AVR-RD-02, US-based gene therapy company Avrobio, Inc's (NASDAQ: AVRO) investigational gene therapy for the treatment of Gaucher disease, the company said.

AVR-RD-02 consists of the patient's own hematopoietic stem cells, genetically modified to express glucocerebrosidase (GCase), the enzyme that is deficient in Gaucher disease.

Avrobio recently dosed the first patient in the GuardOne Phase 1/2 clinical trial to evaluate the safety and efficacy of AVR-RD-02.

The EC grants orphan drug designation to drugs and biologics intended for the safe and effective treatment, diagnosis or prevention of rare diseases or conditions that impact fewer than 5 in 10,000 patients in the European Union.

Orphan drug designation gives companies certain benefits, including reduced regulatory fees, clinical protocol assistance, research grants and 10 years of market exclusivity following regulatory approval.

AVR-RD-02 has also received orphan drug designation from the US Food and Drug Administration.

Gaucher disease is a rare, inherited lysosomal storage disorder characterized by the toxic accumulation of glucosylceramide (GlcCer) and glucosylsphingosine (GlcSph) in macrophages.

Macrophages bloated with these fatty substances are called Gaucher cells which amass primarily in the spleen, liver and bone marrow.

This results in a variety of potential symptoms, including grossly enlarged liver and spleen, bone issues, fatigue, low hemoglobin levels and platelet counts and an adjusted lifetime relative risk of developing Parkinson's disease that may be more than 20 times greater than the general population.

Even on enzyme replacement therapy the current standard of care people with Gaucher disease type 1 typically have a shortened life expectancy and may experience debilitating symptoms that significantly reduce their quality of life.

An estimated 1 in 44,000 people are diagnosed with Gaucher disease.

AVR-RD-02 is an investigational lentiviral gene therapy designed to provide a durable therapeutic benefit for people living with Gaucher disease.

The therapy starts with the patient's own hematopoietic stem cells, which are genetically modified to express functional glucocerebrosidase (GCase).

Functional GCase reduces levels of glucosylceramide and glucosylsphingosine, the accumulated substances which cause the symptoms of Gaucher disease. Avrobio is currently evaluating AVR-RD-02 in GuardOne, a Phase 1/2 clinical trial.

Lentiviral vectors are differentiated from other delivery mechanisms because of their large cargo capacity and their ability to integrate the therapeutic gene directly into the patient's chromosomes.

This integration is designed to maintain the therapeutic gene's presence as the patient's cells divide, which potentially enables dosing of pediatric patients, whose cells divide rapidly as they grow.

Because the therapeutic gene is integrated into the patients' own stem cells, patients are not excluded from receiving the investigational therapy due to pre-existing antibodies to the vector.