Spontaneous canine mammary tumors: A model for monoclonal antibody diagnosis and treatment of human breast cancer

BACKGROUND: The increasing availability of monoclonal antibodies to human breast tumor-associated antigens offers a new means to evaluate whether antigenic similarities exist between human and animal breast tumors. The study of the biology of spontaneous mammary tumors in the dog, one of the most frequent neoplasias in this domestic animal, may be of interest in providing an experimental model for the clinical management of human breast cancer. EXPERIMENTAL DESIGN: In order to assess whether antigenic similarities do occur between human and canine breast cancer, in the present study we have evaluated the immunohistochemical reactivity of two normal mammary glands and 62 benign and malignant canine breast tumors with a panel of six MoAbs, (HMFG₂, MBr1, B72.3, B6.2, X-10, B1.1) recognizing distinct human breast tumor-associated antigens. RESULTS: The results of the present study indicate that mammary neoplasias in dogs display an antigenic phenotype comparable to that observed in female and male human breast lesions. As has already been demonstrated in humans, only three among the six monoclonal antibodies tested (B72.3, B6.2, and X-10) appear to discriminate benign from malignant canine mammary tumors. CONCLUSIONS: These findings demonstrate that (a) this veterinary tumor may represent a suitable model for imaging and immunotherapy studies of human breast carcinoma and (b) the triplet of reagents capable of distinguishing selectively transformed glandular epithelium may be useful in the immunocytochemical presurgical diagnosis of these canine neoplasias.