By Vera Shively and the Genetic Counseling Team at Lurie Children’s
Background: Cells, Genes and DNA
Our bodies are made of trillions of cells. Cells are like tiny factories that make products the body needs to grow and stay healthy. The instructions for making these products are stored in our genes. Each gene is a very long string of DNA molecules. Sometimes the reason that a person has a health problem is because there is a disease causing change in one or more of their genes. These harmful genetic changes may cause cells to make a product that doesn’t work quite right, or even prevent cells from making the product at all.
What Is Gene Therapy & How Does It Work?
Gene therapy is a way to correct these harmful genetic changes. Its purpose is to give cells the right DNA instructions needed to make products that work as they should. It has the potential to treat and cure cancers and genetic disorders. In some genetic conditions, there are no specific treatments. In other genetic conditions, the symptoms are managed with specific drugs, special diets or other medical treatments. This means that treatment must be ongoing and does not correct the underlying genetic change. Gene therapy takes a different approach, treating the genetic origin of the condition, not just the symptoms. The goal is to be able to give a single dose of medicine that has long-lasting effects.
The hard part about gene therapy is getting the correct DNA instructions into cells that can use them. Scientists have developed a variety of carriers to deliver the DNA that is needed. The carriers are called vectors. Special kinds of viruses are often used as vectors. These viruses have been changed so they don’t cause illness and instead are able to insert DNA into cells. In this way, scientists can take advantage of what viruses do naturally, but have modified the process to deliver a corrected genetic change needed by the body.
What Are Some of the Recent Advances in Gene Therapy?
Recent improvements in the design of the viral vectors used for gene delivery have led to increased treatment success. These newer vectors are better at delivering DNA to the right type of cells. This has greatly increased the number of conditions that can now potentially be treated with gene therapy.
What Are the Gene Therapy-Based Clinical Trials Currently in Progress at Lurie Children’s?
There are several gene therapy based clinical trials being conducted at Lurie Children’s. Below is a highlight of two of our clinical trials:
- Beta-Thalassemia: Thalassemia is a blood condition that may lead to heart and bone problems, liver damage and diabetes. People with the disorder have anemia, and often feel tired and weak. Patients with severe disease require regular red blood cell transfusions to treat their symptoms. Early results from the beta-thalassemia gene therapy clinical trials have been promising. Most patients treated with the gene therapy, called LentiGlobin, no longer needed monthly blood transfusions. Alexis Thompson, MD, Head of Hematology and Director of the Comprehensive Thalassemia Program, is leading this trial at Lurie Children’s.
- Mucopolysaccharidosis Type II (MPS II): This condition is also called Hunter syndrome. It is a rare inborn error of metabolism that may affect every organ of the body. Patients with MPS II are unable to breakdown certain types of complex sugar molecules. This leads to an unhealthy build-up of these molecules inside the cell, causing a variety of progressive health problems. A new gene therapy drug, SB-913, is being studied in adult patients with MPS II who do not have developmental disabilities. Barbara Burton, MD, Clinical Practice Director of the Division of Genetics, Birth Defects and Metabolism, is leading this trial at Lurie Children’s.
Genetic Counselors Inform Patients on Advances in Treatment
Genetic counselors guide patients and families in the search for the latest treatment options. We call attention to opportunities for patients to participate in clinical trials. We also help families better understand the benefits, risks and limitations of clinical trials, including those for new gene targeted therapies.