Pneumonitis and concomitant bacterial pneumonia in patients receiving pembrolizumab treatment Three case reports and literature review

초록

Rationale Pembrolizumab, a monoclonal antibody against the programmed cell death 1 (PD-1) protein, can induce a stable regression of some malignancies refractory to conventional chemotherapy. Despite such therapeutic benefits, pembrolizumab can induce immune-related adverse events, with pneumonitis being the most critical problem. Patient concerns All 3 patients complained of fever, cough, and dyspnea after a variable time interval (1–21 days) from pembrolizumab treatment. Diagnoses Chest computed tomography invariably showed ground glass opacity. All tests for possible infectious agents were negative. Based on high procalcitonin level, one of 3 patients was diagnosed to have accompanying bacterial pneumonia. Interventions All patients received antibiotics and steroid treatments (methylprednisolone, 1 mg/kg). Outcomes The 3 patients showed different clinical courses ranging from mild pneumonitis to rapidly progressing respiratory failure. Among the 3 patients, 2 fully recovered with steroid treatment; 1 died from superimposed bacterial pneumonia. Lessons The prognosis of pembrolizumab-induced pneumonitis with a superimposed bacterial pneumonia would be poor. It is important to distinguish pure pneumonitis from that with a superimposed bacterial pneumonia.

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