T cell therapy is a new and experimental therapy used to treat cancer. It falls under the category of “immunotherapy,” which is a type of a cancer treatment that “helps your immune system fight cancer.” When the immune system normally functions, it is responsible for detecting “non-self” organisms/cells and destroying them. These “non-self” cells can be foreign pathogens, but they can also be damaged or mutated host cells (i.e. cancer cells). Even though the immune system can slow, or even stop cancer growth, we all know there must be ways for cancer cells to avoid the immune system because people die from cancer every day. This can include genetic changes that make them “less visible” to the immune system, having proteins on the cell surface that “turn off” immune cells, and changing neighboring cells to interfere with the effectiveness of immune cells. Immunotherapy helps our immune systems combat sneaky cancer cells by making them more efficient.
Chimeric antigen receptor (CAR) T-cell therapy is a new therapy that first gained FDA approval in 2017. It is when T-cells are removed from the body, made “new and improved,” and then returned to the body. They are modified to produce “chimeric antigen receptors” (CARs), which are then added to the cell membrane. When the CAR T cells are reintroduced to the body, the CARs help them better identify and target cancer cells. CAR T-cell therapy has been approved by the FDA for “aggressive, relapsed and/or refractory diffuse large B cell lymphoma (DLBCL), primary mediastinal B-cell lymphoma, and transformed follicular lymphoma (drug names Yescarta and Kymriah),” and “patients age 25 and under with relapsed or refractory B-cell acute lymphoblastic leukemia (drug name Kymriah).” Although this therapy can be very effective, it can also involve significant side effects, such as cytokine release syndrome (CRS). CAR T cells can cause a massive release of cytokines as a part of the immune response, which may cause symptoms such as low blood pressure, high fever, and difficulty breathing. It can also cause brain and nervous system issues. Patients may be confused, or have difficulty understanding language or speaking. Patients may go into anaphylaxis (life-threatening allergic reaction) or get B-cell aplasia (low B cell count). Due to these high-risk side effects, patients are watched carefully during treatment to help prevent life-threatening or long-term effects.
CAR T-cell therapy has its benefits: it is a one-time treatment, and can last beyond the initial infusion due to the ability of white blood cells to multiply and keep a “memory” of the cancer cells they target. This means that treatment is shorter when compared to traditional chemotherapy and radiation options, and that it may be able to prevent recurrence in cases where other treatments will not. It has also expanded the options for people who have already been through unsuccessful traditional treatments (this treatment is currently specifically approved for those who have already attempted other standard therapies). Previously, there wasn’t a “standard of care” for people who had unsuccessfully tried two lines of treatment. However, this treatment is still extremely expensive — from hundreds of thousands of dollars, to over a million when including all additional hospital-related costs.
Clinical trials have given promising results in the early outcomes of CAR T-cell therapy patients with blood cancers, and newer clinical trials are attempting to apply this same therapy to other blood cancers and solid tumors. There isn’t much long-term data for remission rates, etc for obvious reasons, but it is a promising treatment for those who have limited options and previously unsuccessful treatments. This is a new way of thinking about cancer treatments, and new approaches are welcome in the field of cancer research, which seeks to simultaneously increase length and quality of life during and after treatment. Traditional, or standard, cancer treatments have accomplished incredible things, and extended millions of lives over the past several decades, but sometimes they are not effective. New treatments can increase our chances of putting different cancers into remission, and give hope to those who are suffering through unsuccessful therapies. As they say, “there is more than one way to skin a cat,” and sometimes a different approach is needed.
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