Percolation and binding of MAB BW 494 to pancreatic carcinoma tissues during high dose immunotherapy and consequences for future therapy modalities.

ABSTRACT

The distribution of the monoclonal antibody (MAb) BW494 in human pancreatic carcinoma biopsies during high dose i.v. immunotherapy was investigated. Using immunohistochemical techniques combined with anti-idiotypic, endothelial cell specific and bispecific MAbs it was shown that 3 days after onset of immunotherapy, MAb BW494 was bivalently bound to tumor cells in some highly vascualized areas near capillaries. No binding was observed in other highly vascularized tumor cell areas although the epitope detected by MAb BW494 was present. In contrast to our expectation the majority of the tumor cells was not yet saturated by the antibody, probably due to diffusion barriers in the solid tumor tissue.