GX1 targeting delivery of rmhTNFα evaluated using multimodality imaging.

GX1 is a tumor targeting peptide. In this study, we evaluated the antitumor efficacy of a GX1-derived fusion toxin, GX1-rmhTNFα, and investigated its targeting efficiency and pharmacokinetics in vivo using multimodality imaging. Flow cytometry revealed a greater level of cell apoptosis induced by GX1-rmhTNFα (27.1%) compared with rmhTNFα or a saline control (13.7% and 4.7%, respectively). SPECT (single-photon emission computed tomography) demonstrated high accumulation of GX1-rmhTNFα in tumor site. Biodistribution studies indicated GX1-rmhTNFα was cleared by the liver and kidney, and the drug may not cross the blood-brain barrier. In addition, bioluminescence imaging (BLI) showed that GX1-rmhTNFα caused a satisfactory delay in tumor growth in both subcutaneous and orthotopic cancer models. Contrast-enhanced ultrasound (CEUS) and CD31 staining revealed a loss in blood perfusion and vasculature. TUNEL and Ki67 staining validated the in vivo results. Biochemical analyses revealed limited renal and hepatic toxicity of GX1-rmhTNFα. This study demonstrated that GX1-rmhTNFα is a safe and potent anticancer agent that may have great potential for the targeted therapy of gastric cancer.