Tumour uptake of monoclonal antibody after regional intraarterial injection. Biokinetics in the nude rat heterotransplanted with malignant melanoma.

Nude rats were heterotransplanted with human melanoma metastases on both thighs. Ten days later a bolus of 125I-labelled monoclonal antibody (MAb) 96.5 was injected through a catheter in the common femoral artery. The femoral vein was clamped for 15 min to obstruct the venous outflow from the injected leg. The specific tissue uptake (%/g) in the tumour on the injected side compared to the non-injected side showed initially higher uptake (ratio 7.2 at 3 h). After 24 h there were no side differences. The tumour to muscle ratio was 2.8 at 3 h when injected and control sides were compared. Intravenous or subcutaneous injection gave similar specific tissue uptake as regional arterial injection after 24 h. Tissue to plasma ratios were similar after intravenous and subcutaneous injection of monoclonal antibodies. Intraarterial injection of a bolus of labelled monoclonal antibodies and obstructing the venous outflow thus increased the tumour uptake during a short period of time during which the contrast enhancement was three-fold.