Immunotherapy Explained: Benefits, Types, Risks, and Who Should Consider It

Immunotherapy harnesses or modulates the immune system to help the body combat disease, infection, or abnormal cell growth.

The field is evolving rapidly as scientists deepen their understanding of immune mechanisms. Today it is a cornerstone of cancer care—often called the “fifth pillar” alongside chemotherapy, radiation, targeted therapy, and surgery—and it is also used for immunodeficiency disorders, allergic reactions, autoimmune diseases, and more.

Read on to learn when immunotherapy is indicated, the main types available, and the potential risks you should discuss with your physician.

The first scientific breakthrough is credited to German physicians Busch and Fehleisen in the late 1800s, who observed tumor regression after bacterial infections and deliberately injected cancer patients with bacteria to shrink tumors.

In 1891, William B. Coley—widely regarded as the “father of immunotherapy”—applied a similar approach to bone cancer. Sixty‑seven years later, in 1967, researchers identified T‑cell–mediated immunity, laying the groundwork for modern cancer immunotherapy.

In 2018, Dr. James Allison and Dr. Tasuku Honjo received the Nobel Prize for developing checkpoint‑inhibitor therapy, which led the FDA to approve ipilimumab (Yervoy) in 2011. Since then, research has accelerated across many disease areas.

Cancer

Immunotherapy boosts the immune system’s ability to recognize and destroy cancer cells. Each tumor carries roughly 11,000 gene mutations that can serve as unique targets for immune‑based drugs.

Numerous checkpoint inhibitors, CAR T‑cell products, and cancer vaccines have received FDA approval or are in clinical trials for a wide range of malignancies, including melanoma, lung, kidney, and blood cancers.

Primary immunodeficiencies

More than 200 genetic disorders impair immune function. Immunoglobulin replacement therapy—an antibody‑based immunotherapy—is considered one of the most effective treatments, according to the Immune Deficiency Foundation.

Allergic reactions

Allergy immunotherapy involves gradually increasing injections of the specific allergen to desensitize the immune system and reduce symptom severity.

Autoimmune disease

In autoimmune conditions the immune system attacks healthy tissue. Traditional therapies often use broad‑acting immunosuppressants, which can cause significant side effects.

A 2025 review highlighted emerging strategies—checkpoint agonists, CAR T‑cell therapy, and cytokine‑targeted agents—that aim to fine‑tune immune activity rather than blunt it completely. These approaches are still under investigation and have not yet received FDA approval.

Tissue and organ transplants

Immunosuppressive regimens are used to prevent rejection after transplantation. They are typically delivered in two phases:

• Induction: high‑dose agents given at the time of surgery.
• Maintenance: lower‑dose therapy continued long‑term.

• Calcineurin inhibitors
• Antiproliferative agents
• mTOR inhibitors
• Steroids

Inflammatory disorders

Several biologic immunotherapies are approved for inflammatory and autoimmune diseases, for example:

• Tocilizumab (Actemra) – rheumatoid arthritis, juvenile idiopathic arthritis, adult‑onset Still’s disease
• Anifrolumab (Saphnelo) – systemic lupus erythematosus
• Etanercept – rheumatoid arthritis, juvenile idiopathic arthritis, ankylosing spondylitis, psoriasis, psoriatic arthritis
• Inebilizumab (Uplizna) – neuromyelitis optica spectrum disorder

Infectious disease

Immunotherapy for infections is less mature than cancer immunotherapy, but promising advances have been reported for viral‑induced cancers and chronic viral infections.

How immunotherapy works

Therapies either stimulate or suppress immune activity, using different mechanisms:

• Checkpoint blockade: blocks inhibitory pathways that restrain immune cells.
• Adoptive cell transfer: engineers or expands patient T‑cells to improve tumor recognition.
• Oncolytic viruses: viruses engineered to infect and kill cancer cells while activating immunity.
• Cancer vaccines: prime the immune system against tumor‑specific antigens.
• Cytokines: boost various components of the immune response.

Other immunotherapies include allergen shots, intravenous immunoglobulin (IVIG), conventional immunosuppressants, experimental helminth therapy, transfer factors, and routine vaccinations (e.g., chickenpox, COVID‑19, yellow fever).

Potential side effects

Adverse reactions depend on the specific agent and can range from mild flu‑like symptoms to severe, life‑threatening events. The American Cancer Society notes common side effects such as fatigue, skin rash, colitis, hepatitis, and endocrine disorders.

Patients should discuss individual risk profiles, monitoring plans, and cost considerations with their healthcare team.

When might you consider immunotherapy?

A physician may recommend immunotherapy when:

• Your diagnosis has an FDA‑approved immunotherapy with demonstrated survival or quality‑of‑life benefits.
• Clinical trials show promising results for your specific condition.

Conversely, immunotherapy may be avoided if you have uncontrolled autoimmune disease, certain organ dysfunction, or other contraindications that increase the likelihood of severe toxicity.

Medical perspective

“Patients on immunosuppressive regimens should optimize overall health through balanced nutrition, regular exercise, infection‑prevention measures, up‑to‑date vaccinations, and routine health screenings.” – Mia Armstrong, MD

All statements reflect expert opinion and are intended for informational purposes only. Consult your healthcare provider for personalized medical advice.

Immunotherapy continues to expand its role beyond oncology, offering new options for a spectrum of diseases. Discuss with your doctor whether a current or experimental immunotherapy might improve your health outcomes.