Immunotherapy: medical treatment with amazing possibilities

Here at science made simple, we love sharing our passion for science, and helping others who wish to do the same! This blog post is written by Charlotte Cain, a PhD student from New York. 

Immunotherapy: a new type of treatment strategy for cancer. Sounds daunting and a mouthful.

The major use of immunotherapy at the moment is treating cancer with multiple Food and Drug Administration (FDA) approved drugs already on the market. Understanding the basis of the mechanism at play will show the amazing potential for all types of disease treatments in the future.

Crash course on our immune system

Our body develops an immune system when we are in our mother’s womb and protects us throughout our life when it meets infectious agents.

There are two forms of immunity:

By Fvasconcellos 19:03, 6 May 2007 (UTC) – Colour version of Image: Antibody.png, originally a Work of the United States Government, Public Domain, https://commons.wikimedia.org/w/index.php?curid=2067564

The first is what we call innate immunity. It’s our body’s first barrier against outside infections i.e. cells called macrophages and dendritic cells. This system will prevent the entrance of foreign diseases or anything that could carry any, called pathogens, in our system, and attack them if necessary. This system has also evolved so that it can use pieces of these pathogens, called antigens, to show the rest of our immune system that the pathogen in question is not “self”, i.e. that it doesn’t belong to us, and should be destroyed.

The second form of immune defence is called adaptive immunity. This second line of our immune defence adapts by learning from the first barrier. The cells that make up our adaptive immune system, the T and B lymphocytes, can “scan” these antigens and subsequently make antibodies directed against the pathogen.  Antibodies can attach to the antigens and the pathogens, and clear up the infection. At the same time, some of these T and B lymphocytes will make memory versions of themselves in case a second infection with the same pathogen comes along so that our body can react better and faster. That’s the principle of vaccinations!

Our immune system is constantly fighting off foreign pathogens but also cells in our body that go haywire and need to be neutralised. Cancer is exactly that. Cells in our body that go off course and develop their own program that isn’t what they were originally supposed to do! These rogue cells multiply and create tumours, masses of our own cells that are doing harm to our body.

Why does cancer spread?

Cancer is a widespread disease that does not choose depending on age, race or ethnicity. Approximately 40% of people will be diagnosed with cancer at some point in their lifetime (based on research studies conducted between 2010-2012).

Image from Cancer Research UK – What is cancer?

The problem with cancer cells is that they are derived from our cells! Our immune system is not trained to attack itself. There are markers and signals that our immune system uses to guard against this called immune checkpoints. This marker is found at the surface of T lymphocytes and is a protein called PD-1. Other cells will contain its complementary protein PD-L1. Normally, this interaction leads to the lymphocyte moving on and accepting the PD-L1 cell as “self”.

We now know that some tumour cells can develop tricks to evade our immune system. They hijack these immune checkpoints that then tells our immune system that the cancer cells are not dangerous and to move on. For example, tumour cells can express PD-L1 which allows the tumour to continue growing and spreading without intervention from our body’s protective network.

How does immunotherapy fit in?

For decades, we have been developing means of attacking cancer cells through surgery, radiation therapy, and chemotherapy are some of these treatments. Although these have been shown effective for some patients, they are often heavy and taxing treatments on our body and in case of a recurring cancer, you need to start all over again.

Credit: Billion Photos/Shutterstock

Immunotherapy is a type of treatment that will not directly attack your cancer, but boost your immune system to recognise it as dangerous. Almost all immunotherapy in cancer today uses methods of interfering with immune checkpoints. By preventing the cancer cells from using this as a means of escaping, immunotherapy allows for our body to recognise the cancer cells for what they are: targets to be destroyed. Companies today have been focusing on immune checkpoint pathways and design antibodies directed against the ones used by the tumour so that immune cells (i.e. lymphocytes and macrophages) can attack the tumour. Some have also been exploring other methods of attracting immune cells to the tumour, for example designing new molecules, inspired by antibodies, that can physically bring immune cells into contact with tumour cells.

This new method of treating cancer provides for the first time a “cure” for some patients, even those with metastases, which was not the case before the emergence of immunotherapy.

What does the future hold?

This brief breakdown of immunotherapy in cancer treatments is just one example of the potential applications. If we can boost the immune system on command, we can help our body fight off viruses and other infectious diseases. If we can suppress the immune system we can help treat autoimmune diseases, allergies, and even transplant issues tied to organ rejection.

What will be the next step? Will our generation see the end of any kind of disease? Maybe. In the past decade the discoveries and improvements in science have brought us very close to that future. Immunotherapy is one example of a new and out-of-the-box approach to fighting diseases, so who knows what’s around the corner!

 


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