ARID1A and neoplasm: ARID1A is a tumor suppressor gene and several studies showed that ARID1A mutations were associated with increased immune activity and could predict benefits from checkpoint blockade in solid tumors.43–45 In our study, case 9 was negative for PD-L1 expression but also responded to the immunochemotherapy, suggesting that such positive response might be attributed to ARID1A alteration.