A bispecific immunotoxin (DTAT13) targeting human IL-13 receptor (IL-13R) and urokinase-type plasminogen activator receptor (uPAR) in a mouse xenograft model

Abstract

A bispecific immunotoxin (IT) called DTAT13 was synthesized in order to target simultaneously the urokinase-type plasminogen activator receptor (uPAR)-expressing tumor neovasculature and IL-13 receptor expressing glioblastoma cells with the goal of intratumoral administration for brain tumors. The recombinant hybrid was created using the non-internalizing N-terminal fragment (ATF) of uPA and the IL-13 molecule for binding plus the catalytic and translocation portion of diphtheria toxin (DT) for killing. The 71 kDa protein was highly selective for human glioblastoma in vitro showing no loss on binding compared with DTAT and DTIL13 controls. In vivo, DTAT13 caused the regression of small tumors when administered at 10 micro g/day given on a five-dose schedule every other day. DTAT13 was able to target both overexpressed uPAR and the vasculature, as demonstrated by its ability to kill HUVEC cells. Also, mortality studies indicated that DTAT13 was less toxic than DTAT or DTIL13. These findings indicate that bispecific IT may allow treatment of a broader subset of antigenically diverse patients while simultaneously reducing the exposure to toxin required than if two separate agents were employed.

Application of Fullerenes in Nanomedicine: An Update

“…IL-13 receptors are selectively expressed on astrocytoma cells in gliomas. It has been previously reported that IL-13 receptortargeted chemotherapies (diphtheria toxin) [88,89] delivered through lipid nanovesicles (liposomes)…”

A dual-targeting triplebody mediates preferential redirected lysis of antigen double-positive over single-positive leukemic cells

“…33 An impressive array of similar agents has been designed and tested using bispecific scFvs against EpCAM, various growth-factor and cytokine receptors, as well as an urokinase-type plasminogen activator receptor (uPAR), to import toxic cargo into various types of human cancer cells in culture and in mice xenografted with human cancer tissues. [34][35][36][37][38] For most of these agents, investigators have shown that the dualtargeting proteins had more potent anti-cancer activity than the corresponding mono-targeting control agents. We are not aware, however, of any studies attempting to demonstrate directly that the dual-targeting agent indeed preferentially eliminated antigen dp over sp cells when both were present in the same reaction mixture, mimicking the simultaneous presence of both types of cells in an infiltrated cancerous tissue.…”

Novel Gene Therapeutic Approaches to Brain Cancer

“…This receptor (ILI3Rcx2) is different from its physiological counterpart, i.e., IL13/1L4R (170-174). The urokinase-type plasminogen activator (uP A) receptor is also overexpressed in glioblastomas (170)(171)(172)(173)175), as well as receptors for growth factors, such as epidennal growth factor (EGF) receptor (176,177). Importantly, since these receptors are virtually absent in the nonnal brain, they are very attractive targets for targeted therapeutic approaches in glioma, minimizing any putative adverse side effects to nonnal brain tissue.…”

“…Importantly, since these receptors are virtually absent in the nonnal brain, they are very attractive targets for targeted therapeutic approaches in glioma, minimizing any putative adverse side effects to nonnal brain tissue. Thus, ligands of these receptors, such as IL-13, uPA, EGF, and transforming growth factor cx (TGF-cx) have been fused to the catalytic and translocation domains of highly cytotoxic bacterial products, including Pseudomonas (174,177,178) and Diphteria toxins (78,173,175,176), in order to selectively kill glioma cells, but preserving surrounding nonnal brain tissue. These fusion toxins have shown promising results in in vitro and in vivo experiments using murine glioma models and cliniGal trials have shown that direct interstitial infusion can be used to successfully distribute chimeric toxins in tumors in the CNS, achieving anti-tumor responses without systemic toxicity in patients with malignant brain tumors (179).…”