Checkpoint Inhibitor Drugs

Checkpoint inhibitor drugs help immune cells recognise and attack cancer by releasing signals that tumours can block.

Checkpoint inhibitor drugs are medicines used in a form of immunotherapy. They target checkpoint proteins, which act like control signals that keep immune cells from attacking healthy tissue too strongly. Some cancer cells use these signals to hide from immune activity. By blocking a checkpoint, the medicine may help immune cells recognise and attack cancer. The drug does not work by directly destroying every cancer cell in the way some chemotherapy medicines do, and its effect can continue after a treatment visit.

These medicines are commonly given through an intravenous infusion, although the schedule depends on the specific drug and treatment plan. The infusion itself may take time, followed by observation for an immediate reaction. Because the immune system is being redirected, effects can involve organs beyond the tumour. Skin changes, tiredness, bowel changes, cough, joint aches, or changes in hormone function can occur and need to be reported early. A treatment team may use blood tests and symptom checks to look for immune-related effects.

Checkpoint inhibitors may be included when a cancer type, stage, tumour feature, or previous treatment makes immunotherapy suitable. They can be used alone or alongside another cancer treatment. The choice is individual: a specialist considers the cancer diagnosis, overall health, existing immune conditions, medicines, and test results. The treatment plan can change if the cancer responds, remains stable, or causes side effects. See the related guide to [Immunotherapy](/treatments/systemic-therapy/immunotherapy/) for the wider treatment approach.

Depending on the diagnosis, alternatives or complementary approaches may include surgery, radiotherapy, chemotherapy, targeted therapy, hormone therapy, or another immunotherapy medicine. These options work through different mechanisms and may be combined in a planned sequence. A medicine that is suitable for one cancer or person may not be suitable for another. Ask the oncology team how the proposed option fits the treatment goal and whether a tissue or biomarker test affects the choice.

You may have regular appointments for infusions, examination, and blood tests. Keep a record of new symptoms, even when they seem mild or unrelated to treatment. Contact the treatment team promptly for worsening diarrhoea, severe abdominal pain, yellowing of the skin, a new cough or breathlessness, marked weakness, confusion, a widespread rash, or reduced urine. Do not start steroids or stop prescribed medicines without clinical advice; the team may pause treatment or prescribe treatment for an immune reaction.

Tell the team about autoimmune disease, organ transplants, chronic infections, pregnancy, and all medicines or supplements before treatment. Some immune-related effects can appear during treatment or after an infusion, so keep the oncology contact details available even between visits. Vaccines and procedures may need individual planning. A medical alert record stating that you have received checkpoint inhibitor treatment can help other clinicians interpret symptoms and choose safe care.