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✍️Isha Ishtiaq | Medical Writer | Health & Wellness Copywriter
What is immunotherapy? 🤷
Cancer immunotherapy boosts the body's natural immune response, to defend against cancer acceleration.
Cancer is the leading cause of death worldwide. According to latest statistics, the global cancer burden is predicted to be approximately 28.4 million cases by 2040, which underpins the need for effective cancer treatment.
Traditionally, chemotherapy and radiotherapy are used to treat cancer. Now, there is a new promising treatment which is less harsh than traditional approaches. This new class of therapies called immunotherapy works by helping the body fight back by boosting the immune response. The first immunotherapy in cancer treatment was approved in 2011.
Let's break down what's the immune response and immune system to understand better:
The immune system is able to develop a response when a 'non-self' agent is detected in the body. This can include tumour cells, and the immune system can defend against it, using lymphocyte cells. These can be split into T and B cell, that help to recognise the non-self and destroy it. More specifically in cancer, tumour infiltrating lymphocytes (TIL) are key to the reduction of tumours.
However, tumours often manipulate their environments, making immune detection and destruction much harder. The aim of immunotherapy is to boost these immune cells, such as T and B cells, to identify and eliminate cancer cells.
What are active and passive immunotherapies?🧪
There are two ways of immunotherapy: active and passive.
The table below summarizes the difference between them.
Active Immunotherapy | Passive Immunotherapy |
Stimulates the immune system to fight cancer cells by recognizing them as foreign. | Direct administration of immune system components to destroy cancer cells. |
Examples include
| It includes:
|
How does immunotherapy works? ⚖
Immunotherapy works by regulating and optimizing the immune response against cancer in different ways.
Upregulation: Certain immunotherapies increase specific parts of your immune system to be more active against tumours.
Downregulation: Other immunotherapies help to decrease or block tumour mechanisms to suppress unhelpful immune responses.
What are the types of immunotherapy? 🧪
There are different types of immunotherapy based on their modes of action.
1. Adoptive cell therapy
Imagine customizing your immune cells to become cancer-targeting specialists. This is what occurs in adoptive cell therapy. It involves the transfer of T-cells in higher numbers to a better target cancer. This is performed in three ways.
TIL therapy (unmodified) Tumor-infiltrating Lymphocyte (TIL) therapy involves separating your own TILs from cancers, growing them in the laboratory and then reintroducing them into your body. Ultimately, this increases the ability of your immune system to fight cancer.
Engineered T-cell receptor therapy (modified) In this method, specific antigens are introduced to your T-cells, which helps them recognize tumour-specific antigens. These T-cells are then produced in larger quantities and infused back into your body.
CAR T-cell therapy (modified) Chimeric antigen receptors (CAR) are specialized structures that have both an intracellular signaling apparatus and antigen binding. A viral vector is used to transfer these receptors to your T cells, which helps them recognize cancerous cells and destroy them.
2. Immunomodulators
Immunomodulators are like coaches of your immune system. They don't fight the cancer directly but stimulate your immune system to improve the immune response against cancer cells. There are two types of immunomodulators:
Checkpoint Inhibitors Immune checkpoint inhibitors are drugs block specific proteins that prevent your immune system from attacking the cancer cells. For example, Ipilimumab (Yervoy®) is a drug that inhibit CTLA4 to help treat melanoma. Other target molecules in the body include programmed cell death receptor (PD1) and programmed cell death ligand 1.
Cytokines Cytokines are signalling molecules that allow your immune cells to communicate and generate an immune response against target cells. Currently, the FDA has approved only Interleukin-2 (IL-2) and interferon-α (IFNα) as immunomodulatory agents. Aldesleukin (Proleukin®), a synthetic form of Interluekin-2 (IL-2) been developed for the treatment of melanoma and kidney cancer.
3. Targeted Monoclonal Antibodies
Monoclonal antibodies (mAbs) are lab-created molecules that bind to specific targets in cancer cells.
Think of them as guided missiles that specifically target only cancer cells, leaving the healthy cells alone. Researchers have been experimenting with mAb use in cancer treatment of cancer for many years. The first mAb used in cancer research was rituximab, which targets CD20 expressed on the B-cell surface to treat non-Hodgkin lymphoma.
4. Cancer vaccines
Just like vaccines protect your from disease, cancer vaccines immunise against cancers.
Cancer vaccines are a type of active immunotherapy that activate the immune system to recognize and attack cancer cells. These are split into two types:
Therapeutic cancer vaccines are administered to patients to boost immunity. Examples include, Dendritic Cell Vaccines, Peptide Vaccines and DNA vaccines.
Prophylactic vaccines are administered to prevent primary and secondary cancer. The FDA has approved only two prophylactic vaccines, including vaccinations against hepatitis B virus (which protects against types of liver cancer) and human papilloma virus (which protects against cervical cancer).
5. Oncolytic Virus Therapy
Oncolytic virus therapy utilises viruses to kill cancer cells. The concept is quite interesting: using the natural ability of viruses to infect and kill cells to our benefit. In this case, the viruses are specifically directed at cancer cells.
The first oncolytic virus therapy approved by FDA was talimogene laherparepvec (T-VEC), also known as Imlygic, in 2015. This therapy is used for the treatment of melanoma, a serious form of skin cancer. T-VEC uses a genetically modified herpes simplex virus, which is the same type of virus that causes cold sores. However, T-VEC has been engineered to preferentially infect and kill cancer cells while leaving normal cells unharmed.
What are the benefits of immunotherapy in cancer?👍
Although the success rate of immunotherapy is only about 20-40%, the benefits of immunotherapy are numerous.
Targeted Treatment: Immunotherapy can specifically target cancer cells, which may lead to fewer side effects compared to traditional treatments.
Durable response: Some patients experience long-term remission after immunotherapy.
Versatility: Immunotherapy can be used for various types of cancers, including melanoma, lung cancer, and kidney cancer.
What are the challenges of immunotherapy?💪
Despite many benefits, there are several challenges associated with immunotherapy including:
Complexity of Cancer: Cancer is a complex disease with many different forms, making it challenging to develop a one-size-fits-all treatment.
Immune System Variation: Each person’s immune system is unique, which can lead to variable responses to immunotherapy.
Side Effects: Immunotherapy can cause significant side effects, some of which can be severe and impact quality of life.
Resistance: Some cancers may develop resistance to immunotherapy, reducing its effectiveness over time.
Cost: Immunotherapy treatments can be very expensive, which may limit access for some patients.
Identification of Responders: It is difficult to predict which patients will respond well to immunotherapy, leading to challenges in treatment planning.
Combination Therapies: Determining the most effective combination of treatments with immunotherapy requires further research.
What are the side-effects of immunotherapy in cancer? 🤢
While immunotherapy is generally less harsh than chemotherapy, it can still cause side effects, which are often referred to as immune-related adverse events (irAEs).
These may include:
Skin-related issues from toxicity such as rashes and itching.
Fatigue.
Digestive issues including diarrhoea and colitis.
What is the future of cancer immunotherapy? 🤞
Research in cancer immunotherapy is rapidly advancing, with clinical trials exploring new treatments and combinations of therapies.
Immunotherapy represents a significant shift in the treatment of cancer. By empowering the immune system, it opens the door to more effective and personalized cancer treatment options. As research continues, there is hope to see even more breakthroughs in this exciting field.
Edited by: Olivia Laughton | Content Editor | BSc Microbiology, University of Leeds
