A Case of Rapidly Progressive Pneumonitis Induced by Nivolumab in Metastatic Gastroesophageal Adenocarcinoma: Challenges in Diagnosis and Management

Immune checkpoint inhibitors like nivolumab have transformed cancer therapy but are associated with immune-related, sometimes life-threatening, adverse events, including pneumonitis. We report a case of a 55-year-old man with metastatic gastroesophageal adenocarcinoma who developed rapidly progressive pneumonitis within a week of initiating nivolumab and FOLFOX therapy (folinic acid, 5-fluorouracil and oxaliplatin). Despite some initial improvement with antibiotics and ongoing oral steroids, the patient deteriorated rapidly and died. This case highlights the importance of early recognition and aggressive management of immune-related pneumonitis. Clinicians must be aware of such adverse events, maintain a high index of suspicion and adopt a multidisciplinary approach to optimize outcomes, especially given the often subtle and rapidly evolving clinical presentation.