Understanding Gene Modification and Cellular Therapies
The widespread introduction of gene modification and cellular therapies has brought us to the cusp of a health care revolution. These groundbreaking therapies are bringing hope to people with a wide range of previously incurable rare conditions.
While these therapies are costly, they are potentially curative and prevent the need for long-term adherence to complex maintenance medications. The resulting health care savings and the humanistic impacts on quality of life can far exceed the cost of these therapies.
The site of the genetic manipulation is the primary difference between gene modification and cellular therapies. For gene modification, this occurs in the patient’s body (“in vivo”). Cellular therapies leverage an approach where cells are manipulated outside the patient’s body (“in vitro”). Both are capable of treating diseases in ways we never thought possible.
Let’s break down the other similarities and differences between gene modification and cellular therapies.
Gene Modification Therapies Edit DNA
Gene modification therapies edit a patient’s DNA at the site of the gene defect by introducing new genetic code to fill a gap or fix a flaw. This modification provides a correct set of instructions for necessary biological functions. For example, patients diagnosed with hemophilia A don’t have the correct genetic code to instruct cells how to make functional Factor VIII, which is critical to forming blood clots. Without this correct set of instructions, patients have little to no Factor VIII and cannot regulate the bleeding and clotting process. This leads to easily triggered or spontaneous bleeding episodes that could be life threatening. Current therapy consists of replacing the missing factor through frequent intravenous infusions – as often as multiple times a week. Gene therapy offers the potential to correct the gene mistake, leading to patients producing their own Factor VIII just like someone without hemophilia.
One of the first gene modification therapies on the market was Luxturna®, which treats Leber congenital amaurosis (LCA). LCA is a rare, inherited eye disease that can lead to severe vision loss or blindness. LCA is caused by a mutation of a retinal gene that shares responsibility for providing instructions to form various proteins involved in healthy vision. Luxturna, which is administered through a medical procedure one eye at a time, modifies the defective gene so the body can begin producing the necessary proteins. This prevents or drastically slows the rate of vision loss.
Cellular Therapies Treat or Fight Disease Directly
Cellular therapies are created by a process that involves removing cells from the patient’s body and modifying the genes of those cells in a laboratory, essentially programming them to treat or fight a specific disease. These modified cells are then introduced back into the body. These cells can also originate from a live donor.
Chimeric antigen receptor T cell therapies (or CAR-Ts) are a commonly referenced form of cellular therapy currently available in the market. One example is Kymriah®, which treats B-cell acute lymphoblastic leukemia. Kymriah is manufactured specifically for each patient by collecting their immune response cells called T cells, inserting a genetic code, and reintroducing those cells into the patient. The inserted code tells the T-cell how to fight B-cell acute lymphoblastic leukemia.
1 Maude SL, et al. Tisagenlecleucel in Children and Young Adults with B-Cell Lymphoblastic Leukemia. N Engl J Med. 2018 Feb 1;378(5):439-448.
2 Pasquini MC, et. al. Real-world evidence of tisagenlecleucel for pediatric acute lymphoblastic leukemia and non-Hodgkin lymphoma. Blood Adv (2020) 4 (21): 5414–5424.