Learn About Gene Therapy and Cell Therapy

What is cell and gene therapy?

Some people think that gene therapy and cell therapy are the same, but there are important differences.

With cell therapy, doctors insert new cells of a specific type into the body to repair or replace damaged tissues. Doctors can harvest your own cells and then use the therapy to multiply new, healthy cells in the lab before returning them to your body. In other cases, healthy donors provide the new cells. Stem cell transplants (also called bone marrow transplants) are an example of cell therapy.

Gene therapies change genes within cells to treat an inherited or acquired disease. With gene therapy, doctors “fix” a mutated gene (a gene that has changed and no longer works as it should) or replace a mutated gene with a healthy copy by inserting new genetic material into your cells.

How does cell and gene therapy work?

Preparing and administering cell and gene therapies is a complicated and expensive process. And health care providers and other hospital staff must receive extensive training on how to store and handle the cells.

Here is an example of how a therapy… Chimeric antigen receptor (CAR) T cell therapy — used to treat some blood cancers. This therapy changes the genes inside T cells, a type of immune cell, and trains them to find and destroy cancer cells.

This is how the process works:

• Your healthcare provider collects T cells from your blood.
• Scientists in the lab add a gene that helps T cells bind to a specific part of cancer cells.
• Scientists in the lab grow many copies of the altered cells, which are now called CAR T cells. This may take several weeks.
• Your doctor will introduce CAR T cells into your bloodstream so they can attack cancer cells.

What diseases can cell therapy treat?

Cellular therapies have been successful in treating a variety of conditions and diseases, including:

• Autoimmune disorders
• Spinal cord injuries
• Multiple myeloma
• Neurological disorders
• Some forms of leukemia
• Some forms of lymphoma

What diseases can gene therapy treat?

Currently, FDA-approved gene therapies can be used to treat these and other conditions:

• Retinal dystrophy associated with the RPE65 mutation
• Hemophilia B (congenital factor IX deficiency)
• Spinal muscular atrophy (SMA)
• Beta thalassemia
• Duchenne muscular dystrophy

What are the risks of gene and cell therapy?

Both gene and cell therapies can cause life-threatening side effects, so you will need to receive treatment at a large medical center where all staff have received special training.

In cell therapy, which restores the immune system, your body will temporarily be unable to fight infections. Your immune system may also increase to dangerous levels. You can get cytokine release syndrome (CRS) when new multiplying cells flood your bloodstream with chemicals called cytokines. CRS can cause serious respiratory and heart problems, as well as dangerous fevers, headaches, vomiting and diarrhea.

Other possible side effects of cell therapy include allergic reactions, dangerously low blood mineral levels, and low blood cell counts.

Gene therapy requires the use of a carrier, often a virus whose genes have been modified, to deliver the new gene into cells. Your body may respond to the treatment as a threat. If that happens, your immune system can overreact and cause severe inflammation and even organ failure.

It’s also possible that the treatment could target the wrong cells, introduce a new infection, or cause a tumor if the new genes are placed in the wrong place in the DNA.

What are the benefits of gene and cell therapy?

The greatest potential benefit of gene and cell therapy is the possibility of treating or curing a life-threatening or serious disease that has limited treatment options. Gene and cell therapies treat the underlying cause of the disease at the cellular level. When treatment is successful, these disorders stop getting worse or may even disappear completely.

Humans have approximately 20,000 genes, and those genes carry DNA, which tells cells how to behave. This means that gene therapies create changes at the most basic level of the body. That’s why gene therapies are usually one-time treatments. Some cell therapies are once-in-a-lifetime treatments, but others may need to be repeated for certain diseases, such as blood cancer.

Gene and cell therapy now and in the future

Since 2017, the FDA has approved 32 genetic and cellular therapies, and more approvals will surely come in the coming months and years. The American Society for Gene and Cell Therapy (ASGCT) reportsthat almost 3,000 gene therapies and cell therapies will be in clinical development starting in 2023. This is in addition to the 850 cell therapies currently in development, says the ASGCT.