Cemiplimab

Mechanism of action

◎Programmed cell death protein 1 (PD-1) on T cellsCemiplimab

ⓘ The structure shows human PD-1 bound by cemiplimab.

Cemiplimab is a human IgG4 antibody that binds PD-1 and blocks its interaction with PD-L1 and PD-L2, releasing the brake on tumour-infiltrating T cells.

1. Binds PD-1 on T cells
2. PD-L1/PD-L2 binding is blocked
3. Tumour-infiltrating T cells reactivate
4. Tumour cells are attacked

Indications

• Locally advanced or metastatic cutaneous squamous cell carcinoma not suitable for surgery or radiotherapy. Cutaneous squamous cell carcinoma →
• Advanced basal cell carcinoma after, or when unable to take, a hedgehog pathway inhibitor. Basal cell carcinoma →
• Non-small cell lung cancer with high PD-L1, alone or with platinum chemotherapy. Lung cancer →

Adverse effects

Common

• Fatigue
• Rash and itching
• Diarrhoea, nausea, decreased appetite
• Cough and breathlessness
• Muscle and joint pain
• Thyroid dysfunction

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.

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.

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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: Cemiplimab-rwlc 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.