Ipilimumab

Immune checkpoint inhibitors
Immune checkpoint inhibitors
High alert
An error with this medicine can cause serious harm: double checks and protocols are used.

Anti-CTLA-4 antibody for melanoma, often with nivolumab. It causes more immune toxicity (colitis, hypophysitis) than anti-PD-1 drugs.

Updated Nov 1, 2026

Also called: anti-CTLA-4 antibody

Quick facts

Group: Immune checkpoint inhibitors
Target: Cytotoxic T-lymphocyte antigen 4 (CTLA-4)
Used for: Advanced melanoma · With nivolumab · With nivolumab
Key effects: Rash · Diarrhoea · Fatigue
Monitor: Thyroid function · Glucose · Stool frequency
ATC: L01FX04

No doses: the clinician sets them by the current guideline.

Mechanism of action

Cytotoxic T-lymphocyte antigen 4 (CTLA-4)Ipilimumab

The crystal shows human CTLA-4 bound by the ipilimumab Fab, which covers the surface CTLA-4 uses to bind B7 ligands.

Target in 3D: Cytotoxic T-lymphocyte antigen 4 (CTLA-4). PDB structure 5TRU (RCSB PDB, public domain). View the structure at RCSB PDB

CTLA-4 on T cells binds the B7 ligands of antigen-presenting cells and dampens T-cell priming in lymph nodes. Ipilimumab blocks CTLA-4: more T cells are primed, the T-cell repertoire widens and regulatory T cells are less able to suppress the response. The broader, stronger activation explains both durable responses in melanoma and frequent immune toxicity in skin, gut, liver and endocrine glands.

CTLA-4 binds B7 and brakes T-cell priming
Ipilimumab blocks CTLA-4 binding to B7
More T cells are primed; regulatory T cells weaken
Broad antitumour response, frequent immune toxicity

Indications

Advanced melanoma, alone or with nivolumab, and after surgery to prevent recurrence. Melanoma →
With nivolumab: renal cell carcinoma. Renal cell carcinoma →
With nivolumab: colorectal cancer with high microsatellite instability. Colorectal cancer →
With nivolumab: hepatocellular carcinoma. Hepatocellular carcinoma →
With nivolumab: non-small cell lung cancer and malignant pleural mesothelioma. Lung cancer →
Malignant pleural mesothelioma, with nivolumab. Malignant pleural mesothelioma →

Adverse effects

Common

Rash, itching, vitiligo
Diarrhoea
Fatigue
Nausea, decreased appetite

Contraindications

Previous severe immune-mediated reaction to a checkpoint inhibitor (generally not re-exposed)
Caution: active autoimmune disease, organ or allogeneic stem-cell transplant

Key interactions

Systemic corticosteroids and other immunosuppressants: Used to treat moderate to severe immune-mediated reactions; they damp the immune response.
Nivolumab: Added efficacy and more frequent immune toxicity, including rare fatal myocarditis.

What is monitored

Thyroid function (TSH) before starting and regularly
Liver tests and creatinine before each dose
Glucose; cortisol if fatigue or low blood pressure
Stool frequency, cough and breathlessness at each visit
Signs of myocarditis (chest pain, palpitations) and muscle weakness

Administration and safety

Intravenous infusion only, never as a push or bolus, through a line as the product instructions specify.
Look-alike names: the -mab checkpoint inhibitors (nivolumab, pembrolizumab, atezolizumab, cemiplimab, ipilimumab) are checked by full name; products combined with hyaluronidase for subcutaneous use are not interchangeable with the intravenous ones.
Watch for infusion reactions (chills, fever, rash, breathlessness) during the infusion.

Pregnancy and breastfeeding

Blocking PD-1/PD-L1 or CTLA-4 can harm the fetus (IgG antibodies cross the placenta); effective contraception is used during treatment and for months after, and breastfeeding is avoided.

Nursing care

Before each dose, ask about diarrhoea, cough, rash, headache, fatigue, dizziness, thirst or passing more urine, and review thyroid, liver, kidney and glucose results.
Teach the patient that side effects can start weeks or months after a dose, even after treatment ends, and must be reported early.
Teaching: report diarrhoea or blood in the stool, new cough or breathlessness, yellow skin, severe headache, extreme tiredness, chest pain or muscle weakness at once.
Make sure the patient carries information that they receive immunotherapy, for any emergency visit.

Pharmacokinetics

Absorption: Intravenous infusion.
Elimination: Broken down like natural IgG.
Half-life: About 15 days.

Test yourself

Think of the answer, then tap the question to see it.

Where in the immune response does ipilimumab mainly act?

At T-cell priming in lymph nodes, by blocking the binding of CTLA-4 to B7.

A patient on ipilimumab has headache, fatigue and low sodium. Which immune toxicity is suspected?

Hypophysitis (inflammation of the pituitary).

Which causes more immune-related toxicity overall: anti-CTLA-4 or anti-PD-1?

Anti-CTLA-4 (ipilimumab).

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Connections

← Back to the class: Immune checkpoint inhibitors

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: Ipilimumab Injection: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.