CXCL9 and neoplasm: In part, the lack of toxicity may be due to CXCR3‐expressing CAR T cells being unable to efficiently home and infiltrate into the cerebellum, as the cerebellum expressed negligible levels of Cxcl9 and Cxcl10 when compared to the HER‐2‐E0771 tumours (Appendix Fig S6G).