CXCR4 and glioblastoma: However, the small sample size of this clinical study prompted us to investigate the degree of expression of CXCR4 in glioblastoma tumor cells and healthy brain tissue in a larger population, to further examine the potential of [68Ga]Ga-Pentixafor and [177Lu]Lu-Pentixather as, respectively, diagnostic and therapeutic PET agents in glioblastomas.