WHAT ARE THE PRINCIPLES, BENEFITS AND CHALLENGES OF IMMUNOTHERAPY FOR CANCER?
Cancer is a disease that occurs when abnormal cells grow and spread uncontrollably in the body. The immune system is the body’s natural defense against infections and diseases, including cancer. It is made up of white blood cells and organs and tissues of the lymph system. The immune system can recognize and destroy abnormal cells, but sometimes cancer cells can evade or suppress the immune system’s response.
Immunotherapy is a type of cancer treatment that helps the immune system fight cancer. It can boost or change how the immune system works so it can find and attack cancer cells more effectively. Immunotherapy can be used alone or in combination with other treatments, such as surgery, radiation therapy, chemotherapy, or targeted therapy.
Types of immunotherapy
There are several types of immunotherapy that are used to treat different kinds of cancer. Some of the most common ones are:
Immune checkpoint inhibitors: These are drugs that block immune checkpoints, which are molecules on some immune cells that normally regulate the intensity of the immune response. By blocking these checkpoints, these drugs allow the immune system to respond more strongly to cancer cells. Some examples of immune checkpoint inhibitors are pembrolizumab (Keytruda), nivolumab (Opdivo), ipilimumab (Yervoy), atezolizumab (Tecentriq), durvalumab (Imfinzi), and avelumab (Bavencio).
T-cell transfer therapy: This is a treatment that boosts the natural ability of T cells, which are a type of white blood cell, to fight cancer. In this treatment, T cells are taken from the patient’s tumor or blood and modified in the lab to make them more effective against the patient’s cancer. Then, they are grown in large numbers and infused back into the patient’s body. This treatment may also be called adoptive cell therapy, adoptive immunotherapy, or immune cell therapy. Some examples of T-cell transfer therapy are chimeric antigen receptor (CAR) T-cell therapy and tumor-infiltrating lymphocyte (TIL) therapy.
Monoclonal antibodies: These are immune system proteins that are made in the lab and designed to bind to specific targets on cancer cells or other molecules that affect the immune system. Some monoclonal antibodies mark cancer cells so that they can be better seen and destroyed by the immune system. Others block signals that help cancer cells grow or survive. Some monoclonal antibodies carry toxins, such as radiation or chemotherapy, directly to cancer cells. Some examples of monoclonal antibodies are rituximab (Rituxan), trastuzumab (Herceptin), cetuximab (Erbitux), bevacizumab (Avastin), alemtuzumab (Campath), brentuximab vedotin (Adcetris), and ibritumomab tiuxetan (Zevalin).
Cancer vaccines: These are substances that stimulate the immune system to recognize and attack specific antigens, which are substances that trigger an immune response. Cancer vaccines can be made from killed or weakened cancer cells, parts of cancer cells, or antigens that are similar to those found on cancer cells. Some cancer vaccines are given to prevent certain cancers from developing in healthy people who have a high risk of getting them. Others are given to treat existing cancers by boosting the immune system’s response to them. Some examples of cancer vaccines are bacillus Calmette-Guérin (BCG) vaccine for bladder cancer, sipuleucel-T (Provenge) for prostate cancer, and talimogene laherparepvec (Imlygic) for melanoma.
Cytokines: These are proteins that are naturally produced by the immune system to regulate its activity and communication. Cytokines can be made in the lab and given to patients to enhance or restore the immune system’s ability to fight cancer. Some examples of cytokines are interferons (IFNs) and interleukins (ILs).
Immunomodulators: These are substances that modify the immune system’s response to cancer by either stimulating or suppressing it. Immunomodulators can be natural or synthetic molecules that affect different parts of the immune system. Some examples of immunomodulators are thalidomide (Thalomid), lenalidomide (Revlimid), pomalidomide (Pomalyst), and imiquimod (Aldara).
Usage scenarios
Immunotherapy can be used to treat different types of cancer, depending on the characteristics of the cancer and the patient. Some factors that may influence the choice of immunotherapy include:
– The type and stage of the cancer
– The genetic mutations or biomarkers of the cancer
– The previous treatments and their outcomes
– The patient’s overall health and preferences
– The availability and cost of the immunotherapy
Some examples of cancers that are commonly treated with immunotherapy are:
– Melanoma, a type of skin cancer that can spread to other organs
– Non-small cell lung cancer (NSCLC), a type of lung cancer that accounts for most cases of lung cancer
– Kidney cancer, a type of cancer that starts in the kidneys
– Bladder cancer, a type of cancer that starts in the bladder or other parts of the urinary system
– Head and neck cancer, a type of cancer that starts in the mouth, throat, nose, or sinuses
– Hodgkin lymphoma, a type of blood cancer that affects a type of white blood cell called lymphocytes
– Non-Hodgkin lymphoma, a type of blood cancer that affects different types of lymphocytes
– Leukemia, a type of blood cancer that affects immature blood cells in the bone marrow
– Multiple myeloma, a type of blood cancer that affects plasma cells, which are a type of white blood cell that make antibodies
– Breast cancer, a type of cancer that starts in the breast tissue
– Colorectal cancer, a type of cancer that starts in the colon or rectum
– Liver cancer, a type of cancer that starts in the liver or bile ducts
– Pancreatic cancer, a type of cancer that starts in the pancreas
– Prostate cancer, a type of cancer that starts in the prostate gland
– Ovarian cancer, a type of cancer that starts in the ovaries or fallopian tubes
Benefits and challenges
Immunotherapy can offer several benefits for patients with cancer, such as:
– It can target specific molecules or cells that are involved in cancer growth or survival, while sparing normal cells.
– It can work with the body’s natural defense system to fight cancer.
– It can have long-lasting effects by creating immunological memory, which means the immune system can remember and attack the same or similar cancers in the future.
– It can work synergistically with other treatments to enhance their effectiveness or reduce their side effects.
However, immunotherapy also poses some challenges and limitations, such as:
– It can cause serious side effects by triggering an overactive or misdirected immune response that can damage normal tissues and organs. These side effects can include inflammation, rash, fever, fatigue, nausea, diarrhea, colitis, hepatitis, pneumonitis, endocrinopathies, neuropathies, and autoimmune disorders.
– It can be expensive and not widely available in some regions or settings.
– It can be ineffective or less effective for some patients or cancers due to various reasons, such as tumor heterogeneity, immune evasion mechanisms, immunosuppressive microenvironment, low tumor immunogenicity, or lack of predictive biomarkers.
Conclusion
Immunotherapy is a promising and evolving field of cancer treatment that harnesses the power of the immune system to fight cancer. It has shown remarkable results for some patients and cancers, but it also has some challenges and limitations that need to be addressed. Immunotherapy is not a one-size-fits-all approach and requires careful selection and monitoring of patients and treatments. More research and clinical trials are needed to improve our understanding and application of immunotherapy for different types and stages of cancer.
## References
(1) Immunotherapy for Cancer – NCI. https://www.cancer.gov/about-cancer/treatment/types/immunotherapy
(2) What Is Immunotherapy? | Immunotherapy for Cancer – American Cancer Society. https://www.cancer.org/cancer/managing-cancer/treatment-types/immunotherapy.html
(3) Immunotherapy | Canadian Cancer Society. https://cancer.ca/en/treatments/treatment-types/immunotherapy