Pneumonitis Management and Treatment

Etiologies and Incidence

The American Society of Clinical Oncology notes that anti-PD-1/PD-L1 monoclonal antibodies cause pneumonitis in 2-4% of patients, with grade 3-4 events in 1-2% and fatal pneumonitis in 0.2% 1
Combination immunotherapy (anti-PD-1/PD-L1 plus anti-CTLA4) increases pneumonitis risk 3-fold compared to monotherapy, with incidence reaching 10% versus 3% for monotherapy 2
Patients with non-small cell lung cancer have more treatment-related deaths from pneumonitis compared to other tumor types 2

For grade 1 pneumonitis, the National Comprehensive Cancer Network recommends continuing causative therapy with close monitoring; corticosteroids are not required at this stage 3
For grade 1-2 pneumonitis, the European Society for Medical Oncology suggests discontinuing the suspected causative agent immediately and initiating oral corticosteroids: prednisone 1 mg/kg daily or equivalent 3
For grade 3-4 pneumonitis, the American College of Chest Physicians advises hospitalizing immediately and permanently discontinuing the offending agent, and administering high-dose intravenous corticosteroids: methylprednisolone 2-4 mg/kg/day or equivalent 3

Improvement following drug cessation without glucocorticoid therapy strongly supports drug-related pneumonitis, according to the Society for Immunotherapy of Cancer 3
Clinical improvement with glucocorticoid therapy supports but does not definitively confirm drug-related pneumonitis 3
Steroid tapering must be very slow (6+ weeks minimum) as relapses during tapering are well-documented, notes the American Thoracic Society 3
Approximately 2% of non-small cell lung cancer or melanoma patients develop chronic pneumonitis persisting despite immune checkpoint inhibitor discontinuation 4

Do not delay CT imaging for any new respiratory symptom—disease progression, infection, and pneumonitis must be formally excluded, warns the American College of Radiology 1
Do not change initial antibiotic therapy in infectious pneumonitis within the first 72 hours unless marked clinical deterioration occurs, advises the Infectious Diseases Society of America 5
Fatal cases have been reported, making vigilant monitoring of all respiratory symptoms mandatory, cautions the American Society of Clinical Oncology 1