Cerebral nocardiosis in a patient treated with pembrolizumab: a first case report

BACKGROUND: Checkpoints inhibitors (CPIs) are increasingly used for the treatment of several malignancies. The most common side effects are Immune Related Adverse Events, while infectious complications are rare, especially cerebral nocardiosis. CASE PRESENTATION: Here, we report the first clinical case of a cerebral nocardiosis revealed after seizure in a patient treated by pembrolizumab for a metastatic lung cancer, in the absence of any additional immunosuppressive therapy or risk factors for cerebral nocardiosis. The extended evaluation including a brain CT-scan did not reveal any lesion before pembrolizumab. Nevertheless, the 3-month delay between the start of Pembrolizumab and the diagnosis of cerebral nocardiosis suggests that the infection occurred prior to the CPI. Unfortunately, the patient died during treatment for cerebral nocardiosis, while the lung cancer tumor mass had decreased by 80% after the sixth cycle of pembrolizumab. CONCLUSIONS: This case report emphasizes that clinicians should consider diagnoses other than metastasis in a patient with a brain mass and metastatic cancer treated with CPI, such as opportunistic infections or IRAE.