The oncofetal protein, 5T4, is a suitable target for antibody-guided anti-cancer chemotherapy with calicheamicin

• Published in: International journal of oncology Vol. 32; no. 1; pp. 221 - 234
• Main Authors: BOGHAERT, E. R, SRIDHARAN, L, DOUGHER, M, DIJOSEPH, J. F, DAMLE, N. K, KHANDKE, K. M, ARMELLINO, D, RYAN, M. G, MYERS, K, HARROP, R, KUNZ, A, HAMANN, P. R, MARQUETTE, K
• Format: Journal Article
• Language: English
• Published: Athens Editorial Academy of the International Journal of Oncology 2008
• Subjects: Adenocarcinoma - drug therapy; Adenocarcinoma - pathology; Aminoglycosides - therapeutic use; Animals; Antibodies, Monoclonal - therapeutic use; Antibodies, Monoclonal, Humanized; Antigens, Neoplasm - analysis; Antigens, Neoplasm - genetics; Antigens, Neoplasm - immunology; Antigens, Neoplasm - physiology; Antineoplastic agents; Antineoplastic Agents - therapeutic use; Biological and medical sciences; Cell Line, Tumor; Combined treatments (chemotherapy of immunotherapy associated with an other treatment); Female; Humans; Lung Neoplasms - drug therapy; Lung Neoplasms - pathology; Medical sciences; Mice; Mice, Nude; Neoplasm Transplantation; Pharmacology. Drug treatments; Staphylococcus; Transplantation, Heterologous; Tumors; Antineoplastic agent; Immunochemotherapy; Calicheamicin; Targeted therapy; Monoclonal antibody; Metastasis; Ozogamicin; Cancerology; xenograft; Immunotherapy; targeted chemotherapy; gemtuzumab ozogamicin; Human; 5T4 antigen; Orthotopic; Tumor associated antigen; Oncofetal antigen; Gemtuzumab; Rodentia; Malignant tumor; Vertebrata; Chemotherapy; Mammalia; Treatment; Mouse; Animal; Combined treatment; Cancer
• ISSN: 1019-6439; 1791-2423
• DOI: 10.3892/ijo.32.1.221

The oncofetal protein, 5T4, is a tumor-associated protein displayed on the cell membrane of various carcinomas. This molecule is a promising target for anti-tumor vaccine development and for targeted therapy with staphylococcus exotoxin. The potential use of 5T4 as a target for antibody-guided chemotherapy has not been demonstrated. We report oncolytic efficacy and selectivity in vitro and in vivo with immuno-conjugates of calicheamicin (CM) and the anti-5T4 antibody, H8. CM is a potent cytotoxic drug that causes double strand breaks in DNA. Conjugates of CM and H8 were constructed with acid-labile as well as acid-stabile linkers. In vitro, when applied to monolayers of 5T4(+) cells, CM-conjugates targeting 5T4 were consistently more toxic than either free drug or a non-binding control CM-conjugate. This difference was less pronounced on 5T4-deficient cells. In vivo, four 5T4-positive subcutaneous tumor models were treated with conjugates. Efficacy was demonstrated by reduction of tumor growth relative to controls treated with drug vehicle. To evidence selectivity, the efficacy of the anti-5T4 conjugates was compared to the efficacy of H8, a mixture of H8 and calicheamicin, calicheamicin alone or calicheamicin conjugated to the anti-CD33 antibody, hP67.6. In addition, the efficacy and selectivity of an acid-labile conjugate of H8 was evaluated in an orthotopic model for 5T4(+) lung cancer. Increased survival following treatment was used as a parameter of efficacy. Calicheamicin conjugates of H8 were effective and selective in all the examined tumor models. Differences in efficacy between the acid-labile and acid-stabile conjugates depended on the investigated tumor model.