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

Objective: To assess the efficacy of monoclonal antibody (MoAb) B72.3 for i n vivo-immunoscintigraphy of pancreatic carcinoma in nude mice. Design: Experimental controlled animal study. Setting: University hospital, The Netherlands. Subjects: 11 nude mice with subcutaneously xenografted human pancreatic car cinoma. Interventions: Specific MoAb B72.3 and non-specific MoAb MOPC21 were iodina ted with I-131 and injected intraperitoneally in nude mice. Scintigrams wer e taken on days 1-10 and tumour:non-tumour ratios of the regions of interes t (tumour, thorax, abdomen, background) were calculated. The mice were then killed for in vitro tissue counts. Main outcome measures: tumour:non-tumour ratios in vivo and in vitro. Results: Results of immunoscintigraphy on days 1, 2, and 6 were compared. I n the B72.3-group all ratios were only moderately raised, the tumour:backgr ound ratio being the highest (2.35 (SD 0.67)) on day 6. There were no obvio us 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 tumo ur:non-tumour ratios were twice as high in the B72.3-group, suggesting some specificity of this MoAb. Conclusion: The results of our study suggest that MoAb B72.3 is not powerfu l enough for in vivo detection of pancreatic cancer as assessed in this xen ograft model in nude mice.