Immunotherapy - a Game Changer in Treating Cancer

Author: Danielle Wirz. (IG: @kadani_health_sciences)

SCG ID: 2507202018

Our immune system is capable of fighting all kinds of foreign substances, be it viruses, bacteria or parasitic worms. An army of immune cells is constantly on call, ready to catch the next invading pathogen.

However, the immune cells are not just battling threats from the outside - they also battle threats from the inside. One of the biggest is cancer.

What is cancer?

Under normal circumstances, a cell's life cycle consists of growing until it is ready to divide into two daughter cells (mitosis). This process is regulated by a strict control mechanism.

If a cell loses the ability to follow the control mechanism, it either dies (apoptosis) or it begins to divide uncontrollably. The latter can develop into a lump of cells, known as a tumour. A tumour can be benign (harmless) or malignant (harmful).

A malignant tumour has the potential to grow without limit and spread to other parts of your body, leading to the disease we call cancer.

Did you know? Cancer cells are immortal

The immune system vs. cancer

It is the responsibility of the immune cells to take care of any uncontrolled cell growth. They act as quality control, patrolling our bodies and removing abnormal cells before they become a threat.

In early cancer stages, the immune system is in control and capable of detecting and destroying early tumours before they become clinically visible. This is the elimination phase.

If the cancer cells persist and begin to grow more rapidly, they can match the activity of our immune system and force the body into the equilibrium phase.

A patient can sit in the equilibrium phase for years until their cancer is either destroyed or cancer learns to escape our patrolling immune cells, known as the escape phase.

Cancer cells use various tricks to escape. For example, they can develop genetic changes to become less recognisable. The genetic changes give them something like a make-over but instead of a new haircut, they get new surface markers (molecules on their surface). The cancer cells copy the surface marker from the surrounding healthy cells so that they "blend in" and bypass recognition from the immune cells.

How can immunotherapy help us fight back cancer?

Researchers know that our immune cells are not powerless. They simply need to be taught to stop falling for the cancer cell’s tricks. Immunotherapy can help us achieve this.

In broad terms, immunotherapy is a type of treatment that strengthens the patient’s natural immune response to fight cancer.

Current types of immunotherapy for cancer are:

Antibody therapy. Antibodies are proteins produced by immune cells to bind and label pathogens or cells as “dangerous”. A cell labelled by an antibody will be removed by the immune system. Antibodies can be designed in the lab to bind and label cancer cells (shown below)

Figure 1: Designer antibodies grabbing onto a cancer cell

Non-specific therapy. Drugs or other substances that do not specifically target cancer cells, but instead amplify the overall immune response which can help kill cancer cells. For example, the BCG vaccine (used against TB) is used to treat pancreatic cancer.
T-cell transfer therapy (e.g. TCR, CAR). A group of immune cells (T-cells) are taken from a patient and modified in the lab to make them stronger and better able to target and kill cancer cells. Millions of copies are grown in the lab and then given back to the patient. This type of therapy is used in some children with leukaemia and some adults with lymphoma.

Figure 2: The T-cell transfer therapy process

Immune checkpoint inhibitors. Remember the bit about cancer cells getting a make-over? Checkpoint inhibitors prevent the patrolling immune cells from getting "tricked" into thinking a cancer cell is healthy. This allows the immune cells to attack the cancer cells.

While immunotherapy is not yet as widely used as surgery, chemotherapy, or radiation therapy, it is a promising treatment in the fight against cancer. Experts have said that someday for some types of cancer, these immunotherapies will cure patients without any chemotherapy necessary.

The future of Immunotherapy

The future of immunotherapy is bright, especially for check-point inhibitors. Klas Kärre who awarded the 2018 Nobel Prize for the discovery of checkpoint inhibitors even said

“We can beat cancer with it”

A lot of funding flows into immunotherapy research. A quick google search and we found that in 2020 alone, the following companies have received significant investments from venture capitalists, private investors and public grants:

Norway-based Zelluna Immunotherapy (T-cell transfer therapy): €7.5m
Texas-based Shattuck Labs (checkpoint therapy): $118 million
Lyon-based Tollys: €2.3M
Helsinki-based Tilt Biotherapeutics: €18m

References:

Yang, Y., 2015. Cancer immunotherapy: harnessing the immune system to battle cancer. Journal of Clinical Investigation, 125(9), pp.3335-3337. doi: 10.1146/annurev-med-112311-083918
Herr, H., Dalbagni, G. and Donat, S., 2011. Bacillus Calmette-Guérin Without Maintenance Therapy for High-Risk Non–Muscle-Invasive Bladder Cancer. European Urology, 60(1), pp.32-36.
Prize announcement. NobelPrize.org. Nobel Media AB 2020. Wed. 17 Jun 2020. <https://www.nobelprize.org/prizes/medicine/2018/prize-announcement/>
Cancerresearchuk.org. 2020. What Is Immunotherapy| Cancer Research UK. [online] Available at: <https://www.cancerresearchuk.org/about-cancer/cancer-in-general/treatment/immunotherapy/what-is-immunotherapy> [Accessed 17 June 2020].
National Cancer Institute. 2019. Immunotherapy for Cancer. [online] Available at: <https://www.cancer.gov/about-cancer/treatment/types/immunotherapy> [Accessed 17 June 2020].