The immunotherapy Aims to stimulate the immune system of the body against cancer cells. This stimulation of the immune system can be done in particular thanks to checkpoint inhibitors, antibodies or even therapeutic vaccines.

What is the immune system?

The immune system includes all cells and molecules in the human body whose role is to detect abnormal cells and then trigger an action to eliminate them. There are two answers to remember: innate (or natural) immunity and acquired (or adaptive) immunity. THEinnate immunity is Immediate ; it is put in place as soon as the foreign body enters, in order to destroy it without ever having encountered it first. THEacquired immunity adapts to each new pathogen. Following an initial encounter between the immune system and the pathogen, white blood cells will adapt to the aggressor by developing antibodies specific to the latter and remain in the blood. We call them memory lymphocytes. In this way, when the same pathogen arrives in the body, memory lymphocytes come into action and the elimination process will be much faster and more effective.

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Why doesn't the immune system work against cancer cells?

The immune system is very effective in combating abnormal cells that come from outside. However, a cancer cell is an initially normal cell in the human body that will undergo a transformation and then multiply uncontrollably until forming a tumor. The immune system will therefore not immediately recognize it as being abnormal. It must therefore be reactivated to take action and fight against cancer cells. Immunotherapy is based on this principle.

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How does immunotherapy work?

Several ways to stimulate the immune system are under development. Currently, the most common immunotherapy treatments are based on the use ofcheckpoint inhibitors. Tumor cells have the ability to inactivate immune cells using “checkpoints” like CTLA-4 or PD-L1. Checkpoint inhibitors (Anti-PD-L1: Nivolumab, Pembrolizumab... ; Anti-CTLA-4: Ipilimumab...) will block these points, making it possible to remove the inactivity of immune cells, which will be able to resume their role and destroy cancer cells. However, these treatments may cause side effects. Indeed, the implementation of immunotherapy treatment with a checkpoint inhibitor can lead to autoimmune reactions that can attack healthy cells.

Another way to stimulate the immune system is the use ofbispecific antibodies. These antibodies have the particularity of bind to two different cell types ; for example, on the one hand, immune cells (T lymphocytes) and, on the other hand, cancer cells. One reconciling The physical structure of these two types of cells is made, thus facilitating the destruction of the cancer cell by the immune cell.

Les therapeutic vaccines, unlike preventive vaccines, do not aim to prevent a disease but to trigger an immune response against a foreign body already present in the body, such as a cancer cell for example. A therapeutic vaccination technique consists in the introduction into the body of antigens specific to the cancer cell.

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Numerous immunotherapy treatment strategies are being developed as part ofclinical trials. You can find them on the Klineo platform.

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Sources: Inserm, CEA, Institut Curie, Institut Curie, National Cancer Institute, ENS