A small-molecule compound, erianin, was reported to normalize tumor vessels and improve access for CAR-T cells in a glioblastoma mouse model. The approach targets a key immunotherapy bottleneck—how engineered T cells penetrate the vascular barriers created by the tumor microenvironment—by altering vessel structure rather than focusing solely on immune activation. If the translational pathway holds, vessel normalization could become a generalizable adjunct to CAR-T and other cellular therapies in solid tumors, where delivery and trafficking remain central limitations.