Immunotherapy is one of the most exciting and rapidly advancing fields in modern medicine. By harnessing the body's own immune system to fight disease — particularly cancer, autoimmune conditions, and allergies immunotherapy represents a fundamental shift in how we approach treatment. Unlike chemotherapy which attacks all rapidly dividing cells, or surgery which physically removes disease, immunotherapy works by training, boosting, or redirecting the immune system to target specific threats with precision. This article explores what immunotherapy is, how it works, the different types available, current applications, and the remarkable future possibilities this field holds.
What is Immunotherapy?
Immunotherapy (also called biological therapy or biologic therapy) is a type of treatment that uses substances derived from living organisms — or synthetically produced versions of them — to improve, stimulate, or suppress the immune system's response to disease. The immune system is the body's natural defence mechanism — a complex network of cells, tissues, and organs that identifies and destroys pathogens, abnormal cells, and foreign substances.
In healthy individuals, the immune system can identify and eliminate many abnormal cells, including early cancer cells, before they develop into disease. However, some diseases — including many cancers — have developed mechanisms to evade immune detection. Immunotherapy aims to overcome these evasion strategies, giving the immune system the tools it needs to recognise and destroy disease more effectively.
A Brief History of Immunotherapy
The concept of using the immune system to fight cancer dates back to 1891, when the American surgeon William Coley noticed that some cancer patients who developed bacterial infections after surgery experienced unexpected tumour regression. He began deliberately injecting cancer patients with bacteria (later called Coley's toxins), achieving remarkable results in some cases. While his work was largely sidelined by the rise of chemotherapy and radiation, Coley is now recognised as the pioneer of cancer immunotherapy.
The field accelerated dramatically in the late 20th century with the development of monoclonal antibodies (1975), the discovery of cytokines, and the identification of immune checkpoint proteins. The 2018 Nobel Prize in Physiology or Medicine was awarded to James P. Allison and Tasuku Honjo for their discovery of cancer therapy by inhibition of negative immune regulation — the foundation of checkpoint inhibitor immunotherapy, now a standard treatment for many cancers.
How the Immune System Fights Disease
Before understanding immunotherapy, it helps to understand how the immune system works:
- Innate immunity: The rapid, non-specific first line of defence — including physical barriers (skin, mucous membranes), fever, inflammation, and natural killer (NK) cells that destroy infected or abnormal cells.
- Adaptive immunity: The slower but highly specific second line of defence — involving T cells (which directly kill infected or abnormal cells) and B cells (which produce antibodies that mark foreign substances for destruction).
- Immune memory: After encountering a pathogen or abnormal cell, the immune system creates memory cells that enable faster, stronger responses on future encounters — the principle behind vaccines.
Immunotherapy works by enhancing or redirecting one or more of these mechanisms to improve disease outcomes.
Types of Immunotherapy
1. Checkpoint Inhibitors
The immune system has built-in "brakes" called checkpoints — proteins like PD-1, PD-L1, and CTLA-4 — that prevent it from attacking normal cells. Many cancers exploit these checkpoints to hide from immune attack. Checkpoint inhibitors are drugs that block these proteins, essentially releasing the brakes and allowing T cells to recognise and destroy cancer cells.
Checkpoint inhibitors like pembrolizumab (Keytruda), nivolumab (Opdivo), and ipilimumab (Yervoy) have produced remarkable results in melanoma, lung cancer, bladder cancer, and other tumour types — including long-term remissions in patients with previously untreatable advanced cancer.
2. CAR-T Cell Therapy
Chimeric Antigen Receptor T-cell (CAR-T) therapy is a revolutionary personalised treatment. A patient's own T cells are extracted from their blood, genetically engineered in a laboratory to express receptors that specifically recognise cancer cells, and then infused back into the patient in vastly expanded numbers. These engineered T cells seek out and destroy cancer cells with extraordinary precision.
CAR-T therapy has produced remarkable results in certain blood cancers — with some patients achieving complete remissions after all other treatments had failed. It is currently approved for certain leukaemias, lymphomas, and multiple myeloma.
3. Monoclonal Antibodies (mAbs)
Monoclonal antibodies are laboratory-produced proteins that mimic the immune system's ability to target specific threats. They can be designed to bind to specific proteins on cancer cells or immune cells, blocking their function, flagging cancer cells for immune destruction, or delivering toxic payloads directly to cancer cells (antibody-drug conjugates).
Monoclonal antibodies like trastuzumab (Herceptin) for HER2-positive breast cancer, rituximab for B-cell lymphomas, and bevacizumab for various cancers are now standard treatments worldwide.
4. Cancer Vaccines
Unlike preventive vaccines that stop infection, therapeutic cancer vaccines are designed to treat existing cancer by training the immune system to recognise specific tumour antigens. Sipuleucel-T (Provenge), approved for prostate cancer, was the first FDA-approved therapeutic cancer vaccine. Research into personalised neoantigen vaccines — custom-made vaccines targeting the specific mutations in an individual patient's tumour — is a rapidly advancing area of oncology.
5. Cytokines (Interleukins and Interferons)
Cytokines are signalling proteins that regulate immune responses. Interleukin-2 (IL-2) and interferon-alpha have been used in cancer treatment to boost immune activity. While older cytokine therapies have significant side effects, newer formulations with improved targeting are in development.
6. Allergen Immunotherapy (Allergy Shots)
One of the oldest forms of immunotherapy, allergen immunotherapy involves gradually exposing a patient to increasing amounts of an allergen (dust mites, pollen, bee venom) to desensitise the immune system and reduce allergic reactions over time. This is a well-established, evidence-based treatment for allergic rhinitis, asthma, and insect venom allergy.
Immunotherapy in Cancer Treatment — Current Applications
Immunotherapy has transformed the treatment landscape for many cancers. Current approvals include:
- Melanoma: Checkpoint inhibitors have transformed outcomes — 5-year survival rates for advanced melanoma have improved from under 10% to over 40% with immunotherapy.
- Lung cancer: PD-1/PD-L1 inhibitors are now first-line treatment for many non-small cell lung cancers.
- Blood cancers: CAR-T therapy has produced extraordinary results in certain leukaemias and lymphomas.
- Bladder, kidney, head and neck, colorectal cancers: Checkpoint inhibitors have received approval across multiple tumour types.
Future Possibilities of Immunotherapy
The future of immunotherapy is extraordinarily promising. Researchers are actively exploring:
- Personalised neoantigen vaccines: Custom vaccines targeting the unique mutations in each patient's tumour, potentially combined with checkpoint inhibitors for synergistic effect.
- Next-generation CAR-T and CAR-NK therapies: Off-the-shelf allogeneic CAR-T products (not requiring patient's own cells) and CAR-NK cell therapies with improved safety profiles.
- Bispecific antibodies: Antibodies engineered to simultaneously bind cancer cells and T cells, bringing them into proximity for killing.
- Solid tumour immunotherapy: Overcoming the immunosuppressive tumour microenvironment in solid tumours — one of the major current limitations.
- Autoimmune disease treatment: Using regulatory T cell therapies and tolerogenic approaches to treat conditions like type 1 diabetes, rheumatoid arthritis, and multiple sclerosis.
- HIV and infectious disease: Immunotherapy approaches are being explored for HIV, tuberculosis, and antifungal infections.
- mRNA vaccines: Building on COVID-19 vaccine technology, mRNA cancer vaccines are now in clinical trials for melanoma, pancreatic cancer, and other tumour types.
Immunotherapy in India
Access to immunotherapy in India has improved significantly over the past decade. Checkpoint inhibitors are available at major cancer centres including AIIMS, Tata Memorial Hospital, and leading private hospitals in Mumbai, Delhi, Bangalore, and Chennai. The cost of immunotherapy remains a significant barrier for many Indian patients — a course of checkpoint inhibitor treatment can cost several lakhs of rupees. However, biosimilar monoclonal antibodies developed in India have reduced costs for some treatments, and government health schemes are increasingly covering some immunotherapy agents.
⚠️ Medical Disclaimer: This article is for educational and informational purposes only. Immunotherapy is a complex medical treatment that must be administered and monitored by qualified oncologists and specialist physicians. It is NOT suitable for self-treatment. Always consult a qualified cancer specialist or doctor for advice about cancer treatment options. The author is not a licensed medical professional.
References & Further Reading
- National Cancer Institute — Immunotherapy. Cancer.gov
- Allison JP & Honjo T (2018). Nobel Prize in Physiology or Medicine — Cancer Immunotherapy. NobelPrize.org
- Ribas A & Wolchok JD (2018). Cancer immunotherapy using checkpoint blockade. Science. PubMed Link
- World Health Organization — Cancer Treatment. WHO.int
- Wikipedia — Immunotherapy. Wikipedia.org
About the Author: Abhishek Verma is a health and wellness blogger with over 10 years of experience writing about Ayurveda, naturopathy, nutrition, and holistic healing. Need Nutrition is dedicated to making traditional and evidence-based health knowledge accessible to everyday readers.
Also read: Complications in Allopathy | Allopathy: Definition & Principles
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