Since CCNE1 expression is a clinically validated biomarker of WEE1 inhibitor response, we anticipate that individuals with CIC-DUX4 sarcomas, but not other small round blue cell tumors including ES or alveolar rhabdomyosarcoma, will benefit from WEE1 inhibitor treatment. This evidence concerns the gene WEE1 and alveolar rhabdomyosarcoma.