Targeting cancer micrometastases with monoclonal antibodies: a binding-site barrier.

Abstract

Monoclonal antibodies penetrate bulky tumors poorly after intravenous administration, in part because of specific binding to the target antigen. Experiments presented here demonstrate an analogous phenomenon in micrometastases; poor antibody penetration, attributable to a "binding-site barrier" phenomenon, can be seen in guinea pig micrometastases as small as 300 microns in diameter. Increasing the dose of antibody can partially overcome this limitation, but at a cost in specificity.