Management of Isolated Fever After Pembrolizumab Infusion

Clinical Context and Timing

Fever occurring on the first day of pembrolizumab strongly suggests an infusion-related reaction rather than a delayed immune-related adverse event (irAE), as inflammatory irAEs typically present within the first 2 cycles but not during or immediately after the actual infusion 1
Infusion reactions with pembrolizumab occur in approximately 3% of patients and are typically mild, consisting of fever, chills, headache, or nausea 2
Most infusion reactions associated with immune checkpoint inhibitors are mild, with severe or high-grade reactions occurring in <1% of patients 2

The American College of Cardiology is not applicable here, however, the management of Grade 1-2 Infusion Reaction includes administering acetaminophen 650-1000 mg orally for fever control 1
Consider diphenhydramine 25-50 mg orally for additional symptom relief, as per the guidelines from the National Comprehensive Cancer Network [2] [1]
Monitor vital signs closely for the next 24-48 hours for progression to Grade 3-4 reaction, as recommended by the National Comprehensive Cancer Network 1

The American Society of Hematology recommends ER evaluation if temperature ≥40°C (104°F) 1
Hypotension (systolic BP <90 mmHg or drop ≥30 mmHg from baseline) requires ER evaluation, according to the American Journal of Hematology 3
Respiratory symptoms: dyspnea, chest tightness, bronchospasm, or oxygen saturation <92% require ER evaluation, as per the American Journal of Hematology 3
Severe skin reactions: urticaria, angioedema, or rash with blistering require ER evaluation, according to the American Journal of Hematology 3

Infusion reactions occur during or within 24 hours of infusion and include fever, chills, flushing, and mild constitutional symptoms, as defined by the Journal of the American Academy of Dermatology 4, 5
Immune-related adverse events typically present later (within first 2 cycles but not immediately post-infusion) and involve organ-specific symptoms such as pneumonitis (cough, dyspnea), colitis (diarrhea), or hepatitis (jaundice), according to the Journal of the National Comprehensive Cancer Network 2, 6

Outpatient monitoring should include temperature checks every 4-6 hours, as recommended by the National Comprehensive Cancer Network 1
Assessment for development of respiratory symptoms (cough, dyspnea, chest pain) that could indicate early pneumonitis, according to the National Comprehensive Cancer Network 1
Monitoring for gastrointestinal symptoms (diarrhea, abdominal pain) suggesting colitis, as per the National Comprehensive Cancer Network 1
Observation for skin changes beyond simple flushing, according to the Journal of the American Academy of Dermatology 6
Contact oncology team if fever persists >24 hours or any new symptoms develop, as recommended by the National Comprehensive Cancer Network 1

Premedicate with acetaminophen 650-1000 mg and diphenhydramine 25-50 mg 30-60 minutes before infusion, as recommended by the Journal of the American Academy of Dermatology and the National Comprehensive Cancer Network 4, 1
Consider slower infusion rate for next dose, according to the Journal of the American Academy of Dermatology and the National Comprehensive Cancer Network 5, 1
Do not restart at full infusion rate if interruption was required, as per the National Comprehensive Cancer Network 1