Answers to Questions about CALD, Gene Therapy
and Clinical Studies

What is Cerebral Adrenoleukodystrophy (CALD)?

CALD is a rare, fatal, genetic brain disorder. In its most severe form, it is characterized by a breakdown of the protective sheath around the nerves in the brain, called myelin, which surrounds and protects the nerve cells responsible for thinking and muscle control. As breakdown of the myelin occurs, the brain can no longer function properly.

What is gene therapy?

Gene therapy works by using functioning genes as medicine for people who have a gene that is not working properly. The goal of gene therapy is to help correct the genetic disease by providing a functioning copy of the gene to make up for the genetic defect.

How does gene therapy work for CALD patients?

A gene therapy clinical research study, called the Starbeam Study, for patients with CALD, is evaluating an investigational treatment of the disease by transferring a functioning copy of the ABCD-1 gene into a patient’s own blood stem cells.

What is the purpose of the Starbeam clinical study for CALD?

The Starbeam Study will determine if the modified stem cells become a permanent source of brain cells that can break down very long chain fatty acids and prevent demyelination.

Have there been gene therapy studies for CALD using a lentivirus?

An investigational gene therapy using a lentiviral vector was previously used in a clinical study in France to treat four patients with CALD. As of March 2013, the disease stopped progressing in three of the four patients. None of the four patients have experienced serious, unexpected side effects from the investigational gene therapy treatment. However, not all short- and long-term risks are known at this time, and all patients continue to be followed by their physicians.

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Who is sponsoring the study?

bluebird bio, based in Cambridge, MA, is sponsoring the Starbeam Study. bluebird bio is dedicated to developing next generation products based on the transformative potential of gene therapy to treat patients with severe genetic and orphan diseases. bluebird bio will be working with research centers of excellence to conduct the clinical study.