Bevacizumab-Induced Pneumonitis in a Patient With Metastatic Colon Cancer: A Case Report

Bevacizumab is a vascular endothelial growth factor–directed humanized monoclonal antibody used to treat many types of cancer and some eye diseases. Due to inhibition of angiogenesis, many adverse reactions such as bowel necrosis, nasal septal perforation, and renal thrombotic microangiopathy have been described. However, its association with interstitial pneumonitis is scarcely reported in the literature. We report a case of a 79-year-old woman with metastatic colon cancer who presented with cough and dyspnea on exertion the day after initiation of bevacizumab. She was found to have bilateral airspace opacities on imaging. Infectious and cardiogenic etiologies of dyspnea were ruled out. Due to the temporal relationship with the initiation of chemotherapy, she was suspected to have developed bevacizumab-induced interstitial pneumonitis. She improved rapidly with high-dose steroids. Follow-up imaging showed resolution of infiltrates. This is the first reported case in the literature that directly links bevacizumab to interstitial pneumonitis.