SMARCA4-deficient tumors represent a heterogeneous group of malignancies, including thoracic SMARCA4-deficient undifferentiated tumors, SMARCA4-mutated non-small cell lung cancer (non-small cell lung carcinoma), and undifferentiated carcinomas involving the gastrointestinal and gynecologic tracts [4,5,6]. Here, SMARCA4 is linked to undifferentiated carcinoma.