Combatting disease through cell and gene therapy

Ground-breaking research is leading to treatments modifying DNA.

Through gene editing, scientists can treat some genetic disorders by removing a segment of DNA, then replacing a mutated gene or introducing a new or modified gene.
Photograph by nobeastsofierce Science, Alamy

In the fantastical world of science fiction, inserting a gene into the DNA of human cells to treat or cure disease is nothing new. Now, thanks to decades of ground-breaking research and manufacturing breakthroughs by biopharmaceutical and academic researchers, the gene therapy once reserved for futuristic stories is becoming a reality.

Cell and gene therapies use genes and cells to treat disease. This sounds simple, but the reality could not be more complex from a scientific and clinical standpoint. With gene therapy, the treatment involves adding, removing, or altering a gene. With cell therapy, cells are taken either from the patient themselves or a donor, are genetically altered to treat disease, then infused back into the patient. These treatments are often referred to together as cell and gene therapy because they generally involve genetically modifying cells, either inside or outside of the body.

In 2017, the U.S. Food and Drug Administration (FDA) approved the first gene therapy for use in the United States—a treatment for certain pediatric and young adult patients with a form of acute lymphoblastic leukemia. Since then, the agency has approved about 20 cell and gene therapies. When the therapy to repair a genetic form of childhood blindness was approved in December 2017, the childhood vision-loss treatment became the first gene therapy targeting mutations in a specific gene in vivo (in cells in the body), a historic milestone demonstrating that it is possible to use gene therapy to treat some inherited disorders. These new therapies have the potential to cure a number of previously “incurable” diseases and to fundamentally alter the trajectory of many other life-threatening conditions, including many rare diseases. In fact, more than 70 percent of the gene therapies in development are for treatment of rare diseases.

The leap from science fiction to actual cell and gene therapies was made possible by recent advancements in genetic research, the study of human DNA or genetic information to find out what genes and environmental factors contribute to diseases. Genes, which are made up of DNA, are basically the set of instructions the body follows to make each living organism unique. According to the National Institutes of Health, while most human genes are identical among people, a small amount—amounting to less than one percent—differ in subtle ways. Though small, these differences have widespread implications, affecting everything from physical traits, such as eye and hair color, to psychological characteristics like tolerance for risk.

Some people are genetically-predisposed to develop certain diseases, such as diabetes, heart disease, and specific cancers, while other people have a more direct connection between genes and disease. Hemophilia, cystic fibrosis, and certain forms of blindness are among the diseases caused by problems with genes themselves. For example, hemophilia results from mutations in the genes that produce proteins necessary for blood clotting, hampering the body’s ability to prevent excessive bleeding.

While it was only in the 1980s that scientists first began researching the potential of gene therapy to cure genetic disorders, scientists now have a much better understanding of the role that genes play in causing or preventing disease, as well as how to edit, remove, or return genes in a person’s cells. Examples include replacing a mutated gene with a functional copy or introducing a new or modified gene to help treat a disease.

Still, editing genes in the lab is one thing; modifying a patient’s genes in the real world is much more challenging. To ensure a person’s body will accept treatment, today’s gene therapies are sometimes packaged in a delivery vehicle, such as a deactivated virus, to target the correct cells and deliver therapeutic genetic material into them. In this instance, once the new material combines with the patient’s existing genes, affected cells can begin producing the correct protein, effectively fighting or ending the disease. In other examples a patient’s own immune cell are harvested and genetically modified so they can recognize and attack diseased tissue such as a tumor.

According to the November 2018, AdisInsight database for drug research and development, nearly 300 new cell and gene therapies—addressing a wide variety of conditions, such as cancer, cardiovascular disease, and eye disorders—are either in clinical trials or awaiting review by the FDA. Given the potential impact on a wide variety of diseases, biopharmaceutical companies are committed to making potentially life-changing gene therapies a reality for more and more patients.

Learn more about biopharmaceutical innovation, including the breakthrough gene therapies used to treat blood cancers.