IL4 and central nervous system cancer: Based on our preclinical efficacy and safety studies, we have begun a Phase I clinical trial, in which a recombinant chimeric protein composed of circularly permuted IL-4 fused with Pseudomonas exotoxin (cpIL4-PE or IL4(38-37)-PE38KDEL) is administered intratumouraly in patients with high-grade glioma (Rand et al, 2000).