Immune-Related Adverse Events
Immunotherapy drugs alter the way the immune system operates. As a result, they can cause the immune system to attack normal, healthy parts of the body anywhere, resulting in side effects that gradually progress over days or weeks. Before treatment, discuss the signs and symptoms to watch for and what to do if they occur, and the immediate action to take. One of the most important things to remember is that you can’t always recognize the symptoms of irAEs yourself. Having a caregiver who is aware of what to watch for is necessary. Additionally, some of the signs are only discovered as a result of lab work and imaging tests, so always keep your follow-up appointments.
What are the typical reactions?
The most common sites involve the thyroid gland, lungs and skin. Some reactions are low-grade, and some can progress to become life threatening. The most serious side effects are called immune-related adverse events (irAEs).
Table 1 details possible adverse events and symptoms.
When do these events occur?
Skin reactions tend to appear most quickly, at about 3 weeks after treatment begins; colitis (inflammation of the colon) usually begins after 1 to 3 doses of the medication, or about 6 weeks into treatment; hepatitis (disease- causing liver inflammation) begins after 3 to 4 doses, or 8 to 12 weeks into treatment; and endocrine reactions, which affect the glands and organs that make hormones and release them, tend to start 12 to 24 weeks into treatment.
Table 1
Immune-Related Adverse Events (irAEs)
| Body System | irAE | Symptoms and Signs |
| Cardiovascular | Myocarditis | Changes in EKG reading, chest pain, impaired heart pumping function, leg swelling, rapid heartbeat, shortness of breath |
| Endocrine | Endocrinopathies | Alteration in mood, changes in menstrual cycle, diabetes, extreme fatigue, hyperthyroidism, hypothyroidism, persistent or unusual headaches, visual changes |
| Gastrointestinal | Colitis | Abdominal pain or cramping, bowel perforation, diarrhea with or without bleeding |
| Liver | Hepatitis | Abdominal pain, fatigue, fever, nausea, poor appetite, yellow skin or eyes (jaundice) |
| Nervous system | Neuropathies | A burning sensation or loss of feeling in the hands or feet, numbness, pain, sensory deprivation, sensory overload, tingling |
| Neurologic | Encephalitis | Changes in mood or behavior, confusion, extreme sensitivity to light, hallucinations, neck stiffness, seizures |
| Pulmonary/lung | Pneumonitis | Chest pain, fever, shortness of breath, unexplained cough |
| Renal/kidneys | Nephritis | Appetite loss, blood in urine, decreased urination, swollen ankles |
| Skin | Dermatitis | Blisters, itching, painful sores, rash, skin changes |
