Variability of
tumor-associated
antigens among and within human
tumor cell groups presents a potential problem in the development and optimization of immunodiagnostic and therapeutic procedures for
cancer. We determined the degree of expression of a
tumor-associated
antigen in the primary and metastatic lesions of 23 patients with infiltrating
ductal carcinoma; this was accomplished using
monoclonal antibody B72.3, an
IgG1 generated against membrane-enriched fractions of human metastatic
breast carcinomas and reactive with a 220,000-400,000 d
glycoprotein complex, termed
TAG-72, and the
avidin-
biotin complex immunoperoxidase method on fixed tissue sections. Sixteen of the 23
breast carcinomas (70%) demonstrated MAb
B72.3 reactivity (range 5% to 100% of
tumor cells staining). Reactivity of
lymph node metastases was present in 14 of 21 patients (67%). MAb reactivity in
metastases to distant sites, including bone, adrenals, liver, skin and effusions, was present in 10 of 18 patients (56%). In one patient, neither the primary
carcinoma nor the
metastasis to the lymph node demonstrated reactivity. There was a statistically significant positive correlation between MAb
B72.3 reactivity in both primary and
lymph node metastases (Kendall's Correlation Coefficient = 0.60, p = 0.0006) and between lymph node and distant
metastases (Kendall's Correlation Coefficient = 0.48, p = 0.02) of the same patient. No correlation existed between antibody reactivity seen in the primary and that found in the distant lesions of that patient. These studies thus demonstrate that
monoclonal antibody B72.3 can detect expression of a
tumor-associated
antigen in both primary and metastatic infiltrating
ductal carcinoma lesions, and may prove valuable in the understanding of
tumor biology of
metastases and as a means for diagnosing occult disease.