AVROBIO Lentiviral-Based
Gene Therapy

AVROBIO has designed a proprietary, 3rd generation, 4 plasmid lentiviral vector system that is an efficient and proven gene transfer system for the stable addition of genes to the patient’s own CD34+ cells.

Lentiviral gene therapy offers permanent genomic integration, with a demonstrated safety record, for a durable and potential life-long curative benefit. The lentiviral system is a proven approach in gene therapy with > 200 patients successfully treated over the past 15 years.

How Does Lentiviral Gene Therapy Work?

The majority of treatments for life-threatening diseases address symptoms rather than root causes. Many simply delay disease progression but are not curative. This is especially true for rare diseases where existing treatments only manage, but do not cure, the patient’s underlying disease. We believe the solution is to address the root cause – the defective gene. AVROBIO’s lentiviral gene therapy differs from other approaches, as it has the capacity to insert directly into the patient’s genome for a durable and life-long potential curative benefit.  

Lentiviral-based gene therapy has many patient advantages and the fact that the conditioning regimen used in our approach is designed to be performed in an outpatient setting makes it convenient for patients and their doctors. Therapy begins when the patient receives a conditioning agent to stimulate the bone marrow to produce stem cells (CD34+) and release them into the blood. The patient’s peripheral blood stem cells are extracted and genetically modified by adding a new, fully functional copy of the faulty gene. The modified cells are then delivered back into the patient via a one-time infusion. A durable and constant elevation of the enzyme/protein is expected, with the potential to significantly improve patient outcomes and eliminate burdensome and costly lifelong standard-of-care treatments.

Ex Vivo Gene Therapy Clinical Proof-of-Concept Demonstrated for 15+ Years

In 1990, a 4-year old “bubble baby” was the first patient to receive gene therapy to treat severe combined immunodeficiency (ADA-SCID) caused by a defect in the gene for the enzyme, adenosine deaminase. Such early pioneering studies established proof-of-concept for gene therapy by safely treating genetic diseases. Dramatic and lasting results in more than 80 children with ADA-SCID has led leading organizations such as ESID and EBMT, to have guidelines recommending gene therapy as the first option to be considered for all ADA-SCID patients lacking a matched sibling donor. Indeed, gene therapy has now displaced Enzyme Replacement Therapy (ERT) as the standard-of-care. Importantly, there have been no reported serious adverse events in ADA-SCID patients treated with gene therapy. Former “bubble babies” are today having children of their own.

The gene revolution is now in full swing with hundreds of gene therapy products in clinical trials. Importantly, the FDA, EMA, Health Canada and other regulatory authorities around the globe are gaining significant insights in reviewing and understanding the substantial safety and efficacy record associated with gene transfer systems, in particular using lentivirus. Over the past 15 years, approximately 30 of the ADA-SCID children, and another 200 more patients with various genetic diseases, have likewise safely received lentiviral gene therapy. This track record has established lentivirus as a leading delivery system for successfully treating severe genetic diseases.