Relationship between tumour morphology, antigen and antibody distribution measured by fusion of digital phosphor and photographic images

Antibody-directed cancer therapy has achieved encouraging responses despite poor localisation in tumour. This discrepancy may be attributed to heterog eneity of antibody delivery within tumours: preferential localisation in th e better perfused and more radio- and chemosensitive areas provides a thera peutic advantage. Antibody distribution depends upon the interactions of ma ny complex mechanisms. We have started to investigate this by studying the single and combined influence of two tumour-associated parameters, morpholo gy and antigen, on antibody distribution. Tumours were taken from mice at 2 4 and 48 h after I-125-labeled anti-CEA antibody injection. Images of antib ody distribution, antigen distribution and tumour morphology were acquired by radioluminography, radioimmunoluminography and digitisation of morpholog y, respectively. Image registration allowed correlation of pixel values of antibody distribution with corresponding values of antigen distribution and morphology. At 24 h there was little correlation between antibody and anti gen distribution, but strong positive correlation between antibody distribu tion and morphology, with preferential localisation in viable tumour areas. Correlation between antibody distribution and morphology fell significantl y between 24 and 48 h, while that between antibody and antigen distribution remained low. However, the combination of morphology and antigen distribut ion showed the largest influence on antibody distribution. This novel techn ique demonstrates potential for combining multi-factor information in order to provide a greater understanding of antibody distribution in tumours, fa cilitating the optimisation of clinical treatments.