Kinetics, quantitative analysis and radioimmunolocalization using indium-111-HMFG1 monoclonal antibody in patients with breast cancer

HMFG1 tumour associated monoclonal antibody IgG1 and F(ab')2 fragments were radiolabelled with indium-111 and used to study patients with breast cancer. In vitro and in vivo stability of the radiolabelled antibodies was shown to be satisfactory. Thirty patients with primary breast cancer underwent tumour resection and quantitative evaluation of the radioactivity in the tumour and normal tissues following administration of specific and non-specific antibodies. The mean tumour uptake of HMFG1 F(ab')2 fragments at 24 h was significantly higher (P less than 0.05) than the intact IgG but at 48 h there was no difference. The mean tumour uptake with the specific antibody was higher than the non-specific antibody of the same subclass (P less than 0.05). Lymph node metastases showed higher antibody uptake than the corresponding primary tumours (P less than 0.05). Fifteen patients with primary or metastatic breast cancer were investigated by external body scintigraphy using HMFG1 F(ab')2 fragments. Successful localisation was observed in approximately 50% of the primary and metastatic lesions with no false positive results. All the patients had observable concentration of 111In in the liver (20% of the injected dose), the kidneys and the spleen. Following i.v. administration, F(ab')2 fragments cleared from the blood more rapidly than the intact IgG. We conclude that HMFG1 F(ab')2 fragments can localise specifically and faster than intact IgG in breast cancer but the sensitivity of the radioimmunoscintigraphy is relatively low. This method needs further improvement before becoming clinically useful for detecting and staging breast cancer.