A study of tissue samples from 297 pediatric patients with nervous system tumors and rhabdomyosarcoma found that ERBB2 pathway dysregulation was identified in 20–30% of tumor types, though only 4% of the 24 DIPG samples were found to have aberrant ERBB2 pathway activation.15 Furthermore, Vitanza and colleagues18 have recently shown locoregional delivery of balanced CD4:CD8 HER2 CAR T cells for pediatric brain cancer, with demonstrable safety outcomes in three patients (with anaplastic astrocytoma and ependymoma) enrolled on the BrainChild-01 clinical trial (NCT03500991). Here, CD4 is linked to neoplasm.