Immunotherapy for Stomach Cancer

If you have stomach (or gastric) cancer and are discussing treatment options with your cancer care team, you may have heard of immunotherapy. Receiving new information about your treatment, which may include immunotherapy, might be overwhelming and difficult to digest. Understanding how immunotherapy works can be helpful to help you stay on top of medical discussions and prepare you for what to expect when receiving this type of cancer treatment. This article will explore what immunotherapy is, how it works and its use for gastric cancer.

Your immune system comprises a wide network of white blood cells, organs and tissues. Under normal circumstances, it is able to recognize and destroy any substances that are abnormal or foreign to the body, such as bacteria and viruses. This allows your immune system to protect you from all kinds of infections and diseases.

Your immune system is also capable of preventing or slowing cancer growth. However, sometimes, the immune response triggered against cancer cells may not be strong enough to kill them. Cancer cells also have the ability to evade your immune system through various ways. This includes:

• Developing genetic changes that make them less recognizable to your immune system
• Having proteins on the surface of their cells that inactivate immune cells and keep your immune system from attacking them
• Altering surrounding healthy cells so that they interfere with your immune response to the cancer cells

Immunotherapy is a type of cancer treatment that aims to overcome these problems. It works by boosting the ability of your immune system to identify and attack cancer cells, thereby strengthening your body’s immune response to cancer.

Depending on the type and dose you receive, immunotherapy can be administered every two to three weeks or every six weeks as an infusion into your veins (intravenously) during your outpatient visits. It is also typically combined with chemotherapy in the treatment of advanced gastric cancer.

While there are various types of immunotherapy for different cancers, the use of immunotherapy agents in gastric cancer is still fairly new. Only one type of immunotherapy is currently used as part of standard treatment for advanced gastric cancer – immune checkpoint inhibitors (ICIs).

Immune checkpoint inhibitors

To prevent itself from attacking normal and healthy cells in the body, your immune system uses immune checkpoint proteins found on the surface of immune cells. When immune checkpoint proteins attach to partner proteins on other cells, this interaction sends an ‘off’ signal to the immune cells and switches off the immune response, ensuring that healthy cells are not altered.

Some cancer cells are able to use these checkpoints to avoid detection and attack from immune cells. In the case of gastric cancer, some gastric tumors produce excessive amounts of a protein called programmed death-ligand 1 (PD-L1) on the surface of their cells. PD-L1 is a partner protein of programmed cell death protein 1 (PD-1), which is a checkpoint protein found on the surface of immune cells called T cells. When PD-1 binds to PD-L1 on the surface of gastric cancer cells, this interaction signals the T cells not to kill the cancer cells, thereby suppressing the immune response.

ICIs are a class of drugs that are able to target checkpoint proteins and trigger an immune response towards cancer cells. Two ICIs used in the treatment of gastric cancer are nivolumab and pembrolizumab. These drugs work by binding to PD-1 on the surface of T cells and preventing the interaction between PD-1 and its partner protein PDL-1. This enables the T cells to kill the gastric cancer cells, thus shrinking the tumor or slowing cancer growth.

While only two ICIs have been approved by the Food and Drug Administration (FDA), immunotherapy is emerging as a source of promising therapeutics for the treatment of advanced gastric cancer. Other immunotherapies are currently being tested in clinical trials to test their efficacy when combined with other types of cancer treatment, such as chemotherapy and targeted therapy. The results have been encouraging, with several showing notable anti-tumor activity. If you have any questions regarding immunotherapy and whether nivolumab or pembrolizumab can help in the treatment of your gastric cancer, please talk to your doctors and cancer care team. They will provide you with all the relevant information you need to decide if this type of treatment is right for your case.