Solid tumors escape CAR-T cells by expressing different antigens. Researchers engineered glioblastoma CAR-T cells to secrete an EGFR-targeting T-cell engager. In three patients, tumors regressed within days, although responses were transient in two.
CAR-T cells delivered through the bloodstream may not adequately reach brain tumors. In one glioblastoma patient, intraventricular IL13Rα2 CAR-T administration produced regression of all detectable brain and spinal tumors. The response lasted 7.5 months before recurrence.
In a glioblastoma trial, CAR-T cells entered tumors, but surviving cancer cells showed reduced EGFRvIII antigen expression and increased immunosuppressive signals. Targeting multiple antigens may reduce this mechanism of tumor escape.