Synopsis
Recognise and grade multisystem immune-related adverse events, exclude infection and cancer complications in parallel, deliver organ-specific immunosuppression or hormone replacement, and plan a safe taper and rechallenge decision.
- Immune-related adverse events follow checkpoint activation and may affect skin, bowel, liver, lung, endocrine, kidney, nervous, cardiac, eye, joint or blood systems.
- Timing ranges from days after the first dose to months after treatment ends, so previous immunotherapy remains relevant in every acute history.
- Grade from the patient's baseline and organ threat, not symptom count alone; mild fatigue can precede adrenal crisis, myocarditis or neurological overlap.
- Hold checkpoint treatment for clinically important suspected toxicity and investigate immune injury, infection, progression, thrombosis and other medicines together.
- Corticosteroid is first-line for many moderate and severe events, with organ-specific dosing and taper; endocrine failure usually needs hormone replacement rather than high-dose steroid alone.
- Myocarditis, pneumonitis, severe colitis, hepatitis and neuromuscular overlap require early specialist and often critical-care involvement.
- Failure to improve at the protocol-defined interval prompts diagnostic reassessment and organ-specific second-line immunosuppression rather than indefinite steroid escalation.
- Rechallenge is not automatic after recovery; severity, organ, residual deficit, cancer benefit and alternative therapy are reviewed in MDT.
Key red flags
Hypotension, hyponatraemia, hypoglycaemia, severe hyperglycaemia or polyuria can indicate adrenal, pituitary, pancreatic or thyroid emergency.
Chest pain, ptosis, dysphagia, proximal weakness and troponin or CK elevation may represent rapidly fatal overlapping myocarditis and myositis.
Investigation priorities
Detect injury in the symptomatic system and screen multisystem involvement.
Management branches
A new organ symptom or biochemical abnormality occurs after checkpoint exposure.
- Hold immunotherapy when clinically important toxicity is plausible and assess ABCDE stability, baseline function and all involved organs.
- Notify acute oncology and the relevant specialist early for cardiac, neurological, pulmonary, hepatic, bowel or endocrine concern.
- Investigate infection, progression, thrombosis and other medicines concurrently rather than waiting to prove an immune mechanism.
Key medicines
Systemic corticosteroid for significant immune toxicityMany grade 2 toxicities start oral prednisolone 0.5–1 mg/kg/day; many grade 3–4 toxicities use intravenous methylprednisolone or equivalent 1–2 mg/kg/day. The threatened organ can require a different or pulse regimen, so use the current organ-specific protocol and taper commonly over at least 4–6 weeks after objective improvement.Myocarditis, neurological overlap, pneumonitis, colitis and hepatitis need early specialist input and may require different rescue therapy. Monitor infection, glucose, blood pressure, mood, myopathy, gastrointestinal and bone harm; rapid taper risks relapse.
Hydrocortisone for suspected adrenal crisisGive 100 mg intravenously or intramuscularly immediately, then 200 mg over 24 hours by continuous intravenous infusion or 50 mg intravenously or intramuscularly every 6 hours, with rapid 0.9% sodium chloride resuscitation and endocrine input.Do not delay treatment for diagnostic certainty. Protect cortisol before levothyroxine when ACTH deficiency is possible, monitor glucose and electrolytes, then convert to maintenance replacement with sick-day rules and emergency identification.