In vitro studies determined the IC50 values for Tf-CRM107 against T47D (breast carcinoma), SNB40 (human medulloblastoma), and U251 (Human glioblastoma astrocytoma) cells to be between 0.39 and 2.6 × 10–12 M. In nude mice with human gliomas (U251), significant tumor reduction was achieved when treated with Tf-CRM107 (Johnson et al., 1988; Laske et al., 1994; Hagihara et al., 2000). This evidence concerns the gene TF and glioma.