For some B-cell-related blood cancers, the efficacy of CAR-T therapy is unquestionable. Last year, the FDA approved two CAR-T therapies, and many pharmaceutical companies began investing a lot of money and manpower in the field.
However, the clinical application of CAR-T therapy still faces many obstacles, such as toxicity control and low efficiency of solid tumors, which are urgent problems to be solved. And how to develop a general-purpose CAR-T is also the direction that researchers in the field are working hard.
But at the same time, a small number of scientists are also trying to answer another question: Can CAR-T therapy be applied to other disease treatment areas besides cancer?
Many scientists believe that the answer to this question is yes. In addition to cancer, CAR-T therapy is also likely to be used in the treatment of diseases such as viral infections, autoimmune diseases, and rejections caused by organ transplants, and this may open a new direction for CAR-T therapy.
In CAR-T-related therapies for treating cancer, doctors first extract the patient’s T cells, which are transformed into the patient’s body after being engineered and expressing a specific chimeric antigen receptor, thereby identifying and killing the tumor cells. . It should be noted that the currently successful disease areas are all B cell-associated cancers.
However, B cells also play an important role in the pathological process of many autoimmune diseases. Certain types of antibodies secreted by B cells may bind to healthy tissue cells, causing these healthy cells to be attacked by immune cells, thereby causing autoimmune diseases.
So far, these immune diseases have not been cured, and patients can usually receive immunosuppressive drugs, but these drugs may increase the risk of infection and cancer.
Therefore, some researchers are also trying to use CAR-T therapy to treat these diseases. However, unlike CAR-T therapy for cancer treatment, CAR-T therapy for autoimmune diseases does not require the removal of all B cells in the patient, but only the removal of B cells that produce antibodies that cause autoimmune disease: By allowing T cells to express specific CAARs (chimeric autoantibody receptors), it is possible for these cells to recognize specific autoimmune B cells, thereby killing them for the purpose of treating such diseases.
But even this type of CAR-T therapy for autoimmune diseases uses killer T cells. And such T cells are actually only one member of the T cell army. Many researchers are also studying how to use another type of T cell: Treg cells and apply them to CAR-T therapy.
Treg cells can suppress the excessive response of the immune system. The existence of such cells is also a self-protection mechanism of the body, preventing the immune response in the body from being out of control and causing damage to the body. Many autoimmune diseases are also caused by the inability of Treg cells to function properly.
CAR-expressing regulatory T cell therapy
In 2016, a study published by a research team in Canada showed that Treg cells expressing chimeric antigen receptors can suppress immune rejection caused by organ transplantation. This study confirms the feasibility of this treatment strategy for CAR-Treg.
Not long ago, some CAR-Treg-related Phase I clinical studies have shown that these therapies are safe, and they also show that these therapies can delay the progression of type 1 diabetes and control graft-versus-host disease after bone marrow transplantation.
Domestic CAR-T therapy is highly homogenized, and how to conduct differentiated research will be a difficult problem for many companies in the field. Perhaps research focusing on autoimmune diseases and graft-versus-host disease will become a new way for many companies to seek differentiation.