Efficacy Studies of Tn-Directed Therapeutic Antibody and Immunotoxin in Syngeneic Mouse Tumor Models

Tn (N-acetylgalactosamine-O-serine/threonine) is a glycotope known to be overexpressed in various cancers such as prostate cancer, ovarian cancer, colon cancer, cervical cancer, oral squamous cell carcinoma, and breast cancer. Using antigen clustering technology, we have successfully developed an anti-Tn vaccine, which can efficiently induce high affinity and high specificity anti-Tn autoantibodies in mice. Vaccination of TRAMP mice (Transgenic Adenocarcinoma of Mouse Prostate mice that spontaneously generate prostate tumors due to prostate-specific expression of the SV40 T antigen) with the Tn vaccine prolonged the life and inhibited prostate tumor growth and metastasis in TRAMP mice. In order to developed therapeutic antibodies targeted at Tn, we have cloned the cDNAs encoding the mouse anti-Tn antibody in collaboration with Dr. Wu, at DCB. Furthermore, the cDNA encoding a mouse anti-Tn single-chain antibody was also obtained through the collaboration. The recombinant mouse anti-Tn antibody and anti-Tn (single chain) antibody-directed immunotoxin were expressed in CHO cells and E.coli BL21(DE3), respectively. Using these antibody reagents, we plan to carry out animal experiments aimed at demonstrating the antitumor efficacy of these antibodies. The following experiments are proposed: 1. To evaluate the antitumor efficacy of the recombinant mouse anti-Tn antibody in syngeneic tumor mice. 2. To evaluate the efficacy of anti-Tn (single-chain) antibody-directed immunotoxin in syngeneic tumor mice. 3. To evaluate the stimulatory effect of an HDAC inhibitor on the efficacy of anti-Tn antibody and Tn (single-chain) antibody-directed immunotoxin in syngeneic tumor mice.