Efficacy of monoclonal antibody 131I-B72.3 immunoscintigraphy of pancreatic adenocarcinoma xenografts in nude mice

To assess the efficacy of monoclonal antibody (MoAb) B72.3 for in vivo-immunoscintigraphy of pancreatic carcinoma in nude mice. Experimental controlled animal study. University hospital, The Netherlands. 11 nude mice with subcutaneously xenografted human pancreatic carcinoma. Specific MoAb B72.3 and non-specific MoAb MOPC21 were iodinated with 131I and injected intraperitoneally in nude mice. Scintigrams were taken on days 1-10 and tumour:non-tumour ratios of the regions of interest (tumour, thorax, abdomen, background) were calculated. The mice were then killed for in vitro tissue counts. Tumour:non-tumour ratios in vivo and in vitro. Results of immunoscintigraphy on days 1, 2, and 6 were compared. In the B72.3-group all ratios were only moderately raised, the tumour:background ratio being the highest (2.35 (SD 0.67)) on day 6. There were no obvious differences between the ratios of the B72.3-group and the MOPC21-group. The results of tissue counts done at the end of the study, showed that tumour:non-tumour ratios were twice as high in the B72.3-group, suggesting some specificity of this MoAb. The results of our study suggest that MoAb B72.3 is not powerful enough for in vivo detection of pancreatic cancer as assessed in this xenograft model in nude mice