Abstract 4368: Targeting of a radiation inducible tax-interaction protein 1 (Tip 1) as a novel molecule for cancer treatment
Authors: Heping Yan, Kim Nguyen, Vaishali Kapoor, Steve Mnich, Jalen Scott, Hua Li, Buck Rogers, Dinesh Thotala, Dennis Hallahan
Journal: Cancer Research (2015)

Abstract Ionizing radiation (IR) can achieve cell killing and elicit phenotype changes in tumor cells resulting in molecules being expressed on the surface of cells. These molecules can be exploited as targets for tumor imaging and therapy without side effects. We observed Tip1 to be an IR inducible protein (1). Here we report that several clones of anti Tip 1 monoclonal antibodies have been developed and characterized. These antibodies can be used to deliver anti-tumor drugs or radio-isotopes to cancer for Bio-Therapy. Recombinant human Tip 1 produced and used as antigen for McAb production. An IgG2b anti-Tip 1 antibody, 2C6F3, has been characterized and chosen for further studies. Data indicated this McAb had high specificity and affinity to Tip 1. It recognizes a ∼14 kDa protein corresponding to Tip 1 protein by W-B. Tip1 expression increased at 8 and 24 hours after IR treatment in a panel of tumor cell lysate of LLC, D54, A549, PC-3 and GL261. Further, IR increased Tip 1 expression on cultured tumor cell surface. This antibody binds to a panel of tumor cell lines of LLC, D54, A549 and H460 as determined by flow cytometry. A549 cells showed approximately 4 fold increases in Tip1 surface expression and 2 fold increases in D54 cells. The level of Tip1 expressed on H460 cells surface increased 24 hours after irradiation and is dose dependent with 2Gy, 4Gy and up to 8Gy compared with sham treatment (1). Purified monoclonal antibody was conjugated to AF750 and injected intravenously into LLC and GL261 tumor bearing nude mice exposed to either 3Gy x 3 or sham 0Gy treatment. The signal of labeled antibody bound to irradiate tumor was measured and the intensity increased after 24 hours and the signal duration is at least one week. 0Gy sham treated tumor had minor tumor binding and diminished within 24 - 48 hours. The control normal mouse IgG showed no tumor binding over entire course of imaging. IHC data showed that the antibody bound to tumor cells and vasculature in human tumor mouse model. Conjugating the antibody to radio-isotope of 64Cu, 111In, 90Y, 125I was effective for in vivo imaging. The labeling specificity and efficiency was evaluated by ELISA and thin layer chromatography. The radio-isotope conjugated antibody was injected into GL261and LLC tumor bearing mice model for in vivo distribution and micro PET/CT or nano- CT/SPECT imaging. We found that this antibody bound to 3Gy treated GL261 tumors while 0Gy had minimal binding. SPECT imaging showed enhanced tumor binding of 111In and 125I labeled Ab on irradiated LLC tumor in C57/BL at 48 hours. The distribution data reveled high binding of 111In - Ab after 24 -48 hours post irradiation. Also, a dose dependent assay was performed with 90Y conjugated antibody and the data showed 300μCi of labeled 2C6F3 had higher binding on A549 tumor bearing mice model. *Corresponding Author Citation Format: Heping Yan, Kim Nguyen, Vaishali Kapoor, Steve Mnich, Jalen Scott, Hua Li, Buck Rogers, Dinesh Thotala, Dennis Hallahan. Targeting of a radiation inducible tax-interaction protein 1 (Tip 1) as a novel molecule for cancer treatment. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4368. doi:10.1158/1538-7445.AM2015-4368