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Gene Therapy

Gene therapy is one of the newest forms of treatment for certain diseases. It is most often used in research studies called clinical trials.

Gene therapy involves modifying or repairing a faulty gene or replacing an unhealthy or missing gene with a healthy gene. It is under study for blood disorders, neurological disorders, immune disorders, cancer, and other rare diseases. 

Role of genes in disease

Genes are passed from parents to their biological children.

Each gene is a small piece of DNA that contains the genetic code for making a protein. A protein tells the body how to develop and function. It determines traits such as eye color, hair color, and height.

Genes work as a set of instructions to tell the body how to do important jobs. For example, genes transfer the genetic code to RNA. Then, RNA tells the cells in the body how to make proteins. 

Proteins do most of the work in cells. They help the body grow and stay healthy.

Sometimes genes do not work correctly. A mistake in a gene or genes can lead to disease.

Gene-targeted therapy targets DNA and RNA in cells. Its goal is to address the root cause of genetic diseases.

Diseases under study for gene therapy at St. Jude

Diseases under study for treatment with gene therapy at St. Jude include:

Types of gene therapy

There are different types of gene therapy. These include gene editing, RNA modification, and gene transfer.

Gene editing

Gene editing works by correcting mistakes in a gene that causes disease. A gene-editing tool called CRISPR/Cas finds parts of a gene that are not working and then corrects the mistake. St. Jude uses this method to treat sickle cell disease. 

RNA modification

Antisense oligonucleotide (ASO): Another form of gene-targeted therapy is antisense oligonucleotide (ASO). An ASO is a small piece of DNA-like material that is custom-made to attach to a specific segment of DNA or RNA. It changes how a defective gene functions. St. Jude is looking into new ways to use ASO treatments for spinal muscular atrophy and Duchenne muscular dystrophy.

Small-molecule drugs: These are more typical drugs like what you would get at the pharmacy and are designed to modify the RNA to improve the production of a deficient protein.

Gene transfer

Gene transfer, also known as gene addition, repairs the function of a defective or missing gene by adding a new, normal copy of the gene. Gene transfer uses a vehicle called a vector to deliver the healthy gene into the bloodstream, spinal fluid, or diseased tissue. 

Vectors are made from special non-disease-causing viruses that are good at getting into cells and delivering the new gene. Scientists change viruses so that their only function is to carry healthy genes into cells to make them safe for use as vectors. Or viruses are selected for gene therapy because they do not cause disease to begin with. Vectors are tested several times for safety. 

At St. Jude, this method has also been used to treat severe combined immunodeficiency (SCID). Gene transfer has also been used as a treatment approach for the bleeding disorders hemophilia B and hemophilia A.

How gene therapy is given

How gene therapy is given depends on the treatment plan and the type of gene therapy.

In some cases, gene therapy involves removing blood stem cells and modifying the genes in the lab. The patient gets chemotherapy to make room for the new cells before receiving the genetically modified cells back. Then the stem cells with the modified gene are given back to the patient. 

In other cases, the vector may be given directly into a specific tissue in the body. 

Gene therapy may be given in the following ways:

  • Intravenous: Into a vein
  • Intrathecal: Into the spinal fluid
  • Intraventricular: To the brain through a device called an Ommaya reservoir
  • Oral: Given by mouth

In some cases, your child will be admitted to the hospital to prepare for/receive gene therapy and will stay in the hospital to recover after gene therapy. In other cases, your child will get the treatment on an outpatient basis.

Side effects of gene therapy

Side effects of gene therapy depend on the type of treatment used. Each patient reacts to treatment differently. Your child’s care team will explain the possible side effects. The care team will follow your child for several years after gene therapy to see how they are doing.

Government agencies such as the Food and Drug Administration keep track of gene therapy trials. Researchers continue to improve gene therapy techniques. 

Side effects may include: 

  • Unwanted immune system reaction: The body's immune system may see new material as a foreign invader. So, the immune system may attack the tissue that the gene therapy has targeted. 
  • Infection caused by the virus vector: There is a small chance that the virus could cause disease. Scientists alter the viruses so that they will not cause disease. 
  • Chance of causing errors in your genes: There is a small possibility that the treatment can cause errors in your genes and that these errors can lead to diseases such as cancer.
  • Chance of targeting the wrong cells:  Viruses can impact different kinds of cells. Sometimes the modified viruses used in gene therapy might affect some healthy cells, not just the ones that need to be repaired.
  • Side effects from suppressing the immune system’s response to a viral vector: Prednisone, a strong steroid, is commonly used for a month or 2 after the gene therapy is given. This can cause side effects that must be watched and addressed.
  • Symptoms or conditions resulting from chemotherapy: In cases where chemotherapy is given to prepare for the gene therapy, patients may have side effects from the chemotherapy drugs. 

Gene therapy clinical trials

St. Jude offers clinical trials and cancer research studies for children, teens, and young adults who need gene therapy. Learn more about clinical research at St. Jude.

Why St. Jude for gene therapy?

St. Jude is a leader in the study and development of gene therapy to treat and prevent childhood diseases:

  • We have used gene therapy to treat blood diseases, immune disorders, and neurological disorders. Our experts continue to research gene therapy for diseases such as cancer and metabolic disorders. Most patients who are accepted at St. Jude take part in clinical research or clinical trials.
  • Many products needed for gene therapy are made by our Good Manufacturing Practices (GMP) facility on the St. Jude campus.
  • St. Jude researchers are studying ways that health care providers can use gene therapy to treat hemophilia in resource-limited countries.  
  • St. Jude started the GEMINI project to develop new genetic treatments for “ultrarare” neurological disorders. This project is part of the Pediatric Translational Neuroscience Initiative (PTNI). Through PTNI, scientists, care providers, and others work to develop new treatments.
  • The Partnership to Advance Development of Individualized Genomic Medicines (PARADIGM) seeks to develop gene editing cures for rare genetic bone marrow failure disorders.

More reasons to choose St. Jude for care include:

Learn more