Analysis of monoclonal antibody uptake in tumours

Power (y = axb) and linear (y = a + bx) equations were derived, relating percentage uptake (y) of radionuclide tagged specific (SP) and non-specific (NSP) monoclonal antibody (MoAb) and blood flow (BF) to tumour weight (x) in animal models in the literature. Power equations were more significant than linear equations, that is, MoAb uptake and blood flow did not increase linearly with tumour weight. The power equations were similar to the equation relating surface area (SA) to the volume (V) of a sphere (SA = 4.84 V0.67), but with some categorical differences, namely aSP greater than aSA greater than aNSP, aBF and bSA greater than bNSP bBF.bSP was variable. These results can be correlated with tumour physiology. a and b for non-specific MoAb uptake were similar to those for blood flow, suggesting antibody uptake is blood-flow related. Tumours are vascularized from their surface, explaining their relationship to surface area. Autoradiographs show that the high aSP values are due to preferential uptake of specific MoAb by tumours.