Chimeric Antigen Receptor T-Cell Therapy

1. Background

The immune system is the body’s defence against infection and cancer. It is made up of billions of cells that are divided into several different types.

Lymphocytes, a subtype of white blood cells, comprise a major portion of the immune system. 

1.1.There are three types of lymphocytes

• B lymphocytes (B cells) make antibodies to fight infection.
• T lymphocytes (T cells) have several functions, including helping B lymphocytes to make antibodies to fight infection, and directly killing infected cells in the body.
• Natural killer cells also attack infected cells and eliminate viruses. 

1.2.Immunotherapy

• Is a type of treatment that utilizes the body’s immune system to fight cancer
• Improves the body’s ability to detect and kill cancer cells
• Is based on the concept that immune cells or antibodies can recognize and kill cancer cells.

Immune cells or antibodies can be produced in the laboratory under tightly controlled conditions and then given to patients to treat cancer. Several types of immunotherapy are either approved for use or are under study in clinical trials to determine their effectiveness in treating various types of cancer.

2. About Chimeric Antigen Receptor T-Cell Therapy

2.1.T cells are collected from a patient. 

• T cells are collected via apheresis, a procedure during which blood is withdrawn from the body and one or more blood components (such as plasma, platelets or white blood cells) are removed. 
• The remaining blood is then returned to the body.

2.2.T cells are reengineered in a laboratory. 

• The T cells are sent to a laboratory 
• or a drug manufacturing facility where they are genetically engineered, by introducing DNA into them, to produce chimeric antigen receptors (CARs) on the surface of the cells. 

2.3.After this reengineering, the T cells are known as “chimeric antigen receptor (CAR) T cells.” 

• CARs are proteins that allow the T cells to recognize an antigen on targeted tumour cells.

2.4.The re-engineered CAR T cells are then multiplied. 

• The number of the patient’s genetically modified T cells is “expanded” by growing cells in the laboratory. When there are enough of them, these CAR T cells are frozen and sent to the hospital or centre where the patient is being treated.

2.5.At the hospital or treatment centre, the CAR T cells are thawed and then infused into the patient. 

• Many patients are given a brief course of one or more chemotherapy agents, called “lymphodepletion,” before they receive the infusion of CAR T cells. 
• CAR T cells that have been returned to the patient’s bloodstream multiply in number. 
• These are the “attacker” cells that will recognize, and attack, cells that have the targeted antigen on their surface.

2.6.The CAR T cells may help guard against recurrence. 

• CAR T cells may eradicate all of the cancer cells and may remain in the body months after the infusion has been completed. 
• The therapy has resulted in long-term remissions for some types of blood cancer.

3. CART-Cell Therapy in India

• The Chimeric Antigen Receptor T-cell (CAR-T) therapy has emerged as a breakthrough in cancer treatment. 
• Clinical trials conducted globally have shown promising results in end-stage patients, especially in patients suffering from Acute Lymphocytic Leukemia. 
• Though this technology has a remarkable therapeutic potential for cancer patients, at present this technology is not available in India. 
• Each patient's CAR-T cell therapy costs 3-4 crore (INR). 
• The challenge, therefore, is to develop this technology cost-effectively and make it available for the patients.