What immunotherapy is
Your immune system constantly looks for abnormal cells. Some cancers survive by switching on "checkpoint" signals — such as PD-1/PD-L1 or CTLA-4 — that tell immune cells to stand down. Checkpoint inhibitors are antibody medicines that block those signals so immune cells can act. Other forms of immunotherapy include CAR T-cell therapy for certain blood cancers, and some antibodies and vaccines; this page focuses on checkpoint inhibitors, the type most patients in India will encounter.
Immunotherapy is given as a drip, usually every two to six weeks, and treatment often continues for a year or two if it is working and tolerated.
When immunotherapy is considered
Checkpoint inhibitors are now part of standard treatment for a range of cancers — for example some lung cancers, melanoma, kidney cancer, bladder cancer, some head-and-neck, oesophageal and stomach cancers, some triple-negative breast cancers, certain colorectal cancers, and Hodgkin lymphoma. In some situations they are used alone; in others together with chemotherapy, or after surgery to lower the risk of relapse.
Whether it is likely to help you depends on the cancer type and stage and, for several cancers, on biomarkers measured on the biopsy — PD-L1 expression, microsatellite instability (MSI-H) or mismatch-repair deficiency (dMMR), and tumour mutational burden. Those tests are ordered before the decision, not after.
Immunotherapy compared with chemotherapy
- It works differently: chemotherapy attacks dividing cells directly; immunotherapy enables your immune cells to do it.
- Responses can take longer to appear on scans, and occasionally a tumour looks larger before it shrinks. Your oncologist reads scans with this in mind.
- When it works, responses are sometimes long-lasting, even after treatment stops — but it does not work for everyone, and for many cancers the majority of patients do not respond. Honest, biomarker-guided selection matters more than enthusiasm.
- The side effects are different (below) and can appear months into treatment, or after it ends.
Side effects — and why they are different
Because the treatment "releases the brake" on the immune system, the immune system can also attack normal tissue. These immune-related adverse events can affect almost any organ: skin (rash, itching), gut (diarrhoea, colitis), thyroid and other glands (tiredness, changes in weight or blood sugar), liver (usually found on blood tests), lungs (cough, breathlessness), and rarely the heart, nerves or joints.
Most are mild and manageable, but some need prompt treatment with steroids and a pause in immunotherapy. Report new diarrhoea, breathlessness, a persistent cough, severe tiredness, a widespread rash, or any new symptom promptly — even if it seems unrelated. Regular blood tests, including thyroid and liver tests, are part of routine monitoring.
Questions worth asking
- Which biomarker tests have been done on my biopsy, and what did they show?
- For my cancer and stage, what proportion of patients respond, and for how long?
- Is immunotherapy being suggested alone, with chemotherapy, or after surgery — and why?
- Which side effects need an urgent call, and who do I call after hours?
- How long would treatment continue if it works, and when will we check scans?
- Is there a clinical trial that would be reasonable for me?
Cost and access
Checkpoint inhibitors are expensive, and dose, schedule and duration all affect cost. Ask early about what is realistic for you, which options have similar evidence at lower cost, and whether any assistance scheme applies. A plan that cannot be sustained is not a good plan — this is a normal part of the conversation, not an awkward one.
Preparing for your consultation
Bring the biopsy report (and ask whether PD-L1, MSI/MMR or other biomarker testing is on it), all scans with reports, previous treatment details, and a list of medicines — particularly steroids and immune-suppressing drugs, and any history of autoimmune disease, organ transplant or hepatitis, which affect whether immunotherapy is safe.