Glioblastoma multiforme (GBM) is an incurable brain tumor. Due to the strik
ing heterogeneity that characterizes GEM, there is no known tumor-specific
antigen or receptor that is expressed by a majority of GEM patients. We fou
nd that virtually all studied human GEM specimens (23 samples) abundantly e
xpressed a receptor for interleukin (IL)-13 in situ, whereas normal human b
rain had few, if any, IL-13-binding sites. The GEM-associated IL-13 recepto
r was both quantitatively and qualitatively different from and, thus, more
restrictive than the shared signaling receptor of normal tissue: it was IL-
4 independent. The receptor for IL-13 was overexpressed by a majority of ca
ncer cells in situ, Furthermore, cytotoxins targeted to this more restricti
ve IL-13R produced cures in animals bearing xenografts of human high-grade
gliomas, Thus, unexpectedly, the receptor for an immune regulatory cytokine
may be a long sought marker and, concomitantly, a unique imaging site and
therapeutic target for GEM, the most malignant and the most heterogeneous o
f brain tumors.