Immunotherapy for Cancer: Types, Mechanisms, and How It Works

Major Types of Cancer Immunotherapy

1. Immune Checkpoint Inhibitors

Block “brakes” (checkpoint proteins like PD-1/PD-L1, CTLA-4) on T cells, enabling them to attack cancer cells.

• Examples: pembrolizumab (Keytruda), nivolumab (Opdivo), atezolizumab (Tecentriq), ipilimumab (Yervoy).

2. Adoptive Cell Therapy (ACT)

Patient’s own immune cells are collected, modified/expanded in lab, and reinfused.

• CAR T-cell therapy: T cells engineered with chimeric antigen receptors (e.g., tisagenlecleucel, axicabtagene ciloleucel).
• TIL therapy: Tumor-infiltrating lymphocytes expanded and reinfused.

3. Cancer Vaccines

Stimulate immune response against tumor-specific antigens.

• Prophylactic (e.g., HPV vaccine prevents cervical cancer).
• Therapeutic (e.g., sipuleucel-T for prostate cancer; personalized neoantigen vaccines in trials).

4. Oncolytic Viruses

Genetically modified viruses that selectively infect and lyse cancer cells, releasing antigens to stimulate immunity.

• Example: talimogene laherparepvec (T-VEC) for melanoma.

5. Checkpoint Modulators / Agonists

Activate co-stimulatory receptors (e.g., OX40, GITR, CD40 agonists) to enhance anti-tumor immunity.

Why Immunotherapy Matters

Unlike chemotherapy, immunotherapy can produce durable responses and immunologic memory. It is now standard for many cancers (melanoma, lung, kidney, bladder, lymphoma, etc.) and continues to expand.