From the Guidelines
Pneumonitis is a potentially serious toxicity characterized by inflammation of the lung tissue, which can be triggered by various factors including immune checkpoint inhibitors, with an overall incidence of 2.7% reported in patients treated with PD-1 inhibition 1.
Definition and Causes
Pneumonitis occurs when the tiny air sacs in the lungs (alveoli) become irritated and inflamed, making it difficult to breathe and potentially causing permanent scarring. It can be triggered by exposure to allergens, chemicals, radiation therapy, certain medications, or autoimmune conditions.
Symptoms and Diagnosis
Common symptoms include shortness of breath, dry cough, fatigue, loss of appetite, and unintentional weight loss. The diagnosis of pneumonitis is based on clinical presentation, radiologic findings, and laboratory tests. Ground-glass opacities or patchy nodular infiltrates, predominantly in the lower lobes, are common findings on chest imaging 1.
Treatment and Management
The primary treatment approach involves removing the triggering substance if possible and using corticosteroids like prednisone to reduce inflammation. In severe cases, oxygen therapy or immunosuppressant medications may be necessary. The treatment of patients with symptomatic ICPi pneumonitis with corticosteroids is recommended as an initial treatment, based on several studies that report clinical improvement in > 80% of cases 1.
Key Considerations
Pneumonitis can progress to pulmonary fibrosis, causing permanent lung damage if left untreated. The condition differs from pneumonia because pneumonitis is non-infectious inflammation, while pneumonia is typically caused by infection. Anyone experiencing persistent breathing difficulties should seek medical attention promptly for proper diagnosis and treatment. Some key points to consider in the management of pneumonitis include:
- The role of transbronchial biopsy is currently debated but generally not required 1
- The decision to proceed with biopsy should be taken after careful risk-benefit analysis 1
- The treatment of patients with steroid-refractory pneumonitis is not standardized, but options include infliximab, mycophenolate mofetil, intravenous immune globulin (IVIG), or cyclophosphamide 1
From the Research
Definition of Pneumonitis
- Pneumonitis is defined as a focal or diffuse inflammation of the lung parenchyma 2
- It is a known, potentially fatal toxicity of anti-programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) immune checkpoint inhibitors 2
Types of Pneumonitis
- Hypersensitivity pneumonitis: an immunologically mediated lung disease caused by repeated inhalations of organic antigens 3
- Immune-related pneumonitis: an uncommon but potentially life-threatening adverse event associated with anti-programmed cell death protein-1 therapy 4
Clinical Presentations
- Acute form: flu-like symptomatology, followed by dyspnea and dry cough 5
- Subacute form: progressive dyspnea and dry cough, with constitutional symptoms such as fatigue, anorexia, and weight loss 5
- Chronic form: insidious onset of dyspnea, coughing, and weight loss, with possible superimposed acute episodes 6
Diagnosis
- Diagnosis usually rests on a variable combination of findings from history, serology, radiography, lung biopsy, and bronchoalveolar lavage 6
- Characteristic findings include diffuse ground-glass opacification, centrilobular ground-glass opacities, air trapping, fibrosis, lung cysts, and emphysema on radiologic examination 6
- Bronchoalveolar lavage reveals a significant increase in lymphocytes, mostly over 40% 5