Immunotherapy is an exciting and active area of research and investigation in the cancer world. Immunotherapies are treatments that help the body’s own immune system fight cancer. Although there are several different types of immunotherapies being used to treat cancer, let’s look more closely at PD-1 inhibitors.
The Immune System & Checkpoint Proteins
The immune system works in two different ways:
1. Destroying foreign invaders such as bacteria or viruses
2. Destroying the body’s own cells that have abnormal mutations such as cancer cells
In order to keep the immune system from attacking healthy cells, the body has checkpoint proteins. PD-1 is a type of checkpoint protein found on T-cells. T-cells, which are a type of white blood cell, act as the body’s bouncers by destroying foreign invaders and cancer cells. The PD-1 checkpoint proteins keep the T-cells from destroying healthy cells by acting as an “off switch.” This suppresses the immune system’s response. The PD-1 checkpoint recognizes healthy cells by attaching to the PDL-1 protein found on the surface of healthy cells.
Typically, the immune system does a good job at distinguishing between healthy cells and cancer cells. However, sometimes cancer cells are able to “disguise” themselves as healthy cells by covering themselves in PDL-1. This “tricks” the checkpoint proteins into flipping the off switch and stopping the immune system from attacking the cancer cell. If enough of the cancer cells survive, they can multiple and grow into a tumor.
PD-1 inhibitors treat cancer by blocking the PD-1 checkpoint protein. This ruins the cancer cell’s disguise and releases the brakes put on the immune system by the PD1 checkpoint proteins. The T-cells are free to attack and destroy the cancer cells.
Two PD-1 inhibitors have already been approved by the U.S. Food and Drug Administration (FDA) to treat multiple cancer types. Nivolumab is approved to treat certain types of lung cancer, melanoma, kidney cancer, and lymphoma. Pembrolizumab is approved to treat certain types of head and neck cancer, lung cancer, and melanoma. Both are given to patients through an IV infusion, like traditional chemotherapy. Typically, the side effects from these drugs are less severe than traditional chemotherapy.
All new cancer treatments, such as PD-1 inhibitors, must go through a heavily regulated clinical trial process to be approved by the FDA. This process ensures that treatments are safe and effective. All the current treatments used for cancer were once investigated through a clinical trial. Without clinical trials, cancer care cannot improve.