PDCD1 and brain neoplasm: This finding is consistent with previous studies reporting that similar alterations in these pathways in gliomas, another type of brain tumor, are associated with increased responsiveness to PD-1 antibody therapy.41 However, our study also suggests that the Notch and Hippo signaling pathways may serve as potential markers for predicting the lack of durable benefit from chemotherapy combined with PD-1 immunotherapy.