CancerQuest | How Antibody Treatments Work

Our immune system performs its job remarkably well. It is possible that many abnormal cells are eliminated by the immune system before they can progress to cancer. Unfortunately many cancer cells tend to go unnoticed by the immune system because they originate from normal body cells. Despite the fact that they behave like foreign organisms within our bodies, cancer cells often do not elicit a significant immune response. The use of the immune system and its products in the treatment of cancer has yielded promising results.

Antibodies can be used to inhibit the growth of cancer cells in several different ways:

Antibodies that stimulate cell killing: These antibodies function by targeting proteins on the surface of cancer cells. The antibodies themselves mark the cell for destruction by cells of the immune system. This process is termed antibody dependent cellular cytotoxicity (ADCC).⁽¹⁾
Blockage of receptors: These antibodies may function as a blockade to the receipt of required growth signals.
Immunotoxins: This approach utilizes antibodies to target toxic molecules to the cancer cells. These toxic molecules can be proteins that inhibit cellular activities or radioactive compounds that cause DNA damage and the induction of apoptosis.

The first two mechanisms of action are depicted in the diagram below:
In the top image, antibodies (purple) bound to a cancer cell (blue) are recognized by killer T-cells (aqua) via specific antibody receptors (yellow) on the surface of the T-cells. These cells then produce toxic compounds that kill the cancer cell.

In the second mechanism, the bound antibodies block the attachment of growth factors (green) to the cancer cell, depriving it of required pro-growth signals.

antibody treatment

The third mechanism is shown below. Antibodies carrying a toxic substance target the drug to cancer cells leading to the internalization of the poison and the death of the cancer cells.