What is immunotherapy?
Immunotherapy is a treatment that uses substances to boost or suppress the immune system, helping the body fight cancer, infections, and other diseases. It can target specific immune cells or have a broader impact and includes cytokines, vaccines, BCG, and certain monoclonal antibodies.
Evolution of Immunotherapy
The concept of the immune system dates back to ancient Greece, but the first immunotherapy trial occurred in the 18th century in London. Dr. Charles Maitland began experimenting by infecting children with small amounts of smallpox, using pus from infected individuals. The children showed symptoms but recovered without scarring. Encouraged by these results, the Princess of Wales allowed Maitland to inoculate six prisoners, none of whom became ill when exposed to smallpox afterward. This led to further inoculations to prevent the disease. While the understanding of the immune system progressed from these early efforts, the use of immunotherapy in cancer treatment wasn’t explored until later.
What are different types of immunotherapy?
Immunotherapy comes in various forms, each enhancing or educating the immune response to target cancer cells. Each type has specific side effects and effectiveness varies by cancer type. Treatment options depend on a patient’s overall health and cancer type.
- Adoptive cellular therapy
Adoptive cellular therapy enhances the quantity and/or efficacy of immune cells, primarily T cells, thereby strengthening the immune response against cancer.
Adoptive cellular therapy includes four main types:
1. Chimeric antigen receptor (CAR) T cell therapy: Genetic modification of T cells to target cancer.
2. Chimeric antigen receptor (CAR) NK cell therapy: Enhances natural killer cells with chimeric receptors for better cancer recognition.
3. Tumor-infiltrating lymphocyte (TIL) therapy: Extracts T cells from a tumor, amplifies them in the lab, and reinfuses them into the patient.
4. Endogenous T cell (ETC) therapy: Uses T cells from the patient’s blood, selectively multiplying those that recognize cancer markers before reinfusion.
- Immunomodulators/immune system modulators
Immunomodulators can be categorized into four groups: adjuvants, agonists, cytokines, and checkpoint inhibitors. Checkpoint inhibitors block immune checkpoints, which tumors exploit to evade immune responses. Cytokines regulate the development and activity of immune cells, while agonists stimulate innate immune cells and help activate “killer” T cells against cancer. Adjuvants in the innate immune system trigger nonspecific immune responses that can lead to adaptive responses.
- Targeted Antibodies
Targeted antibodies represent a type of cancer immunotherapy that can interfere with the functions of cancer cells and activate the immune system to identify and destroy those cells.
- “Naked” Monoclonal Antibodies (mAbs): These antibodies are designed to specifically target antigens present on cancer cells, such as trastuzumab for breast cancer that is HER2-positive.
- Antibody-Drug Conjugates (ADCs): These formulations transport cytotoxic medications directly to cancer cells, exemplified by ado-trastuzumab emtansine for breast cancer.
- Bispecific Antibodies: These are created to target two distinct elements at the same time, like blinatumomab, which connects T cells with cancer cells for acute lymphoblastic leukemia.
- Cancer vaccines
Cancer vaccines are a type of immunotherapy that train the immune system to recognize and eliminate cancer cells. Preventive vaccines, like the HPV vaccine, protect against infections that may lead to cancer. Therapeutic vaccines target unique antigens on cancer cells, while neoantigen vaccines personalize treatment by developing vaccines based on the specific antigens in an individual’s tumor.
- Oncolytic Virus Therapy
Oncolytic virus therapy represents a distinctive method in immunotherapy, employing viruses that specifically target and eliminate cancer cells. These viruses are modified to selectively focus on malignant cells while leaving healthy tissues unharmed. Furthermore, this treatment enhances the immune system’s capacity to eliminate any residual cancer cells.
What types of cancer does immunotherapy treat?
Immunotherapy has demonstrated significant success in managing advanced stages of cancers such as lung cancer, melanoma, advanced bladder cancer, and kidney cancer, among others. It is essential to recognize that the range of cancers that can be treated with immunotherapy is continually expanding as additional drugs are tested in clinical trials.
References
- Schuster, M., Nechansky, A., & Kircheis, R. (2006). Cancer immunotherapy. Biotechnology Journal: Healthcare Nutrition Technology, 1(2), 138-147.
- Mellman, I., Coukos, G., & Dranoff, G. (2011). Cancer immunotherapy comes of age. Nature, 480(7378), 480-489.
- Waldmann, T. A. (2003). Immunotherapy: past, present and future. Nature medicine, 9(3), 269-277.
- Taefehshokr, S., Parhizkar, A., Hayati, S., Mousapour, M., Mahmoudpour, A., Eleid, L., … & Taefehshokr, N. (2022). Cancer immunotherapy: Challenges and limitations. Pathology-Research and Practice, 229, 153723.
- Wang, Y., Wang, M., Wu, H. X., & Xu, R. H. (2021). Advancing to the era of cancer immunotherapy. Cancer Communications, 41(9), 803-829.
