First-Line Treatment of Advanced Thoracic SMARCA4-Deficient Undifferentiated Tumor: A Case Report and Review of the Literature.

Thoracic SMARCA4-deficient undifferentiated tumor (SMARCA4-UT) of the chest is a highly aggressive smoking-related thoracic malignancy with a median overall survival (OS) of only 4-7 months. In this article, we report a case of a 74-year-old male patient who was admitted to the hospital with recurrent cough with sputum and CT suggestive of a right pleural occupying lesion. Admission to the hospital and perfect CT showed right pleural thickening with multiple metastases in the mediastinum and liver, and the diagnosis of SMARCA4-UT (SMARCA4 expression deletion) was confirmed by pathologic biopsy and immunohistochemistry. The genetic test map suggested high PD-L1 expression (TPS 80%) and the patient was treated with sindilizumab (200 mg q3w) combined with bevacizumab (500 mg q3w). Grade 3 immune myocarditis occurred during treatment, and bevacizumab maintenance therapy was continued after discontinuing immunosuppression. During follow-up, the patient achieved a final OS of 18 months. This case suggests that PD-1 inhibitors combined with antiangiogenic therapy may improve the prognosis of SMARCA4-UT, but the adverse effects observed during the treatment course demanded equally critical attention.