Methods: Immunohistochemistry and western blot was used to show the expression of NKX 6.1 in check details the gastric cancer tissues and cell lines. Results: In our study, expression

of Nkx 6.1 was examined by IHC in most of the fresh gastric cancer tissues. In addition, Nkx 6.1 expressed at high levels in gastric cell lines SGC 7901, MGC 803 and HGC 27. Conclusion: Our finds suggest that Nkx 6.1 is expressed in gastric cancer cell lines. Key Word(s): 1. Gastric cancer; 2. Nkx 6.1; 3. IHC; Presenting Author: NADIR ARBER Additional Authors: SHIRAN SHAPIRA, DINA KAZANOV, SARAH KRAUS, ITAI BENHAR Corresponding Author: SHIRAN SHAPIRA, DINA KAZANOV, SARAH KRAUS, NADIR ARBER Affiliations: Tel-Aviv Sourasky Medical Center; Tel Aviv University Objective: Background: CD24, a heavily glycosylated GPI-anchored protein,

was proven as a valid target in GI malignancies. Anti-CD24 mAb treatment induces a significant growth inhibition of cancer cells, in a time- and dose-dependent manner, and reduces tumor growth in vivo. Aim: Engineer anti-CD24 chimeric, humanized and matured full-length IgGs, smaller derivatives, and toxin-immunconjugates. Methods: Methods: Edman-degradation, cDNA synthesis, sequence and computational analysis were performed to reveal the entire DNA sequence of the murine Ab. Replacement of the Fc with human IgG1 resulted in a mouse-human Enzalutamide mouse chimera. A scaffold human Ab was chosen for grafting critical sequences of the murine antibody into it. The immunotoxins were constructed first by non-covalent linking via the ZZ-protein (derived from Staphylococcus aureus). Then a bacterial system allowed a covalent linkage between the toxic molecule and the Ab. Sophisticated and high-efficiency engineering-technologies were established to construct, express and purify 15 novel anti-CD24 derivatives in tissue or bacterial cultures. Their binding-affinity, selective-targeting and cytotoxic activities were confirmed in several CD24-expressing GI tumors cells. Results: Results: The chimeric and humanized forms

have high affinity and Org 27569 selectivity towards the CD24 antigen that work additively with standard chemotherapies. The immunotoxins were superior to the unarmed Ab with lower IC50 values. Antibody targeting and accumulation within the tumor and its excess clearance was clearly demonstrated using direct imaging (SWA11-ZZ-mCherry-HIS fluobody). The scFv-toxin killed CD24-expressing cells with an IC50 of 1 μg/ml, while the values for the IgG-ZZ-toxin were lower (0.02-0.05 μg/ml). The IC50 values of the humanized anti-CD24(di/tetra)-PE38 and the scFv were similar, suggesting that the absence of post-translational modifications, in the E.coli-producing IgG, affected reactivity. MTD studies confirmed no toxicity at high dose of 40 mg/kg. Conclusion: Conclusion: Targeting CD24 may be a promising treatment for GI malignancies.