Question

10. Recent anti-cancer therapies focus on harnessing the immune system of the human body. A variety of approaches are being used and explored. For each of the anti-cancer therapies listed below, present a specific example of such a therapy and explain the proposed mechanism of action to describe how the therapy works.

1. Monoclonal antibody.

A monoclonal antibody will bind to an antigen

2. Vaccination against a specific microbe.

3. Use of T cells (e.g. CAR-T therapy).

Answer 1

Anticancer therapies:

a) Monoclonal antibody therapy: Monoclonal antibodies are antibodies that produced in the laboratory, and are designed to serve as substitutes of the natural or innate antibodies that would detect and fight the cancer cells. These antibodies bind specifically to antigens present more frequently on the surface of cancer cells. They help in targeting the cancer cells for attack by the immune cells. They can also block the growth of cancer cells by limitng the supply of growth factors from the cell's surroundings or by promoting disintegration of cell membrane.

Example: Rituximab is a monoclonal antibody that binds to the surface of certain types of cancer cells and allows those cells to be targeted by B-cells from the immune system.

b) Vaccine therapy: This strategy involves live vaccination using live bacterial and viral vectors. This strategy results in the development of a long-term immune response for targeting and eliminating cancer cells.

Example: Bacteria such as Salmonella and Listeria have been reported to colonize and destroy tumors. Attenuated bacterial strains are used to target and attack cancerous cells. Similarly, viruses such as Vaccinia and Adenoviruses can infiltrate cancerous cells. The presence of these viruses in the cancerous cell results in the production of antigens on the surface of the cancer cell. The immune system recognizes these antigens and T-cells are induced to target and destroy the cancerous cells harboring the virus.

c) CAR-T therapy: In this strategy, T-cells from the patient are extracted and modified in the laboratory to enable them to identify cancer cells. The modified T-cells are called Chimeric Antigen Receptor (CAR) T-cells. They are able to identify specific antogens on the surface of the cancer cells and attack them.

Example: Tisagenlecleucel is a CAR-T therapy used to treat patients with Acute Lymphoblastic Leukemia (ALL). This CAR-T cell is able to target CD19, a marker on B-cells that are adversely affected by B-cell ALL.