MCA, a Monoclonal-Antibody-Defined Breast-Tumor-Associated Antigen and Its Relation to CA 15.3

Abstract

A mucin-like carcinoma-associated antigen (MCA) was recently identified on the surface of established breast cancer cell lines by several monoclonal antibodies. The antibody b-12 was used in a sandwich enzyme immunoassay to measure MCA concentrations in serum samples and other biological fluids. The upper limit for noncancerous women and men was 14 U/ml. MCA levels were independent of estrogen or prolaction secretion. 63% of patients with metastatic breast cancer had elevated serum concentrations of MCA. Elevated MCA levels were also associated with cervical, ovarian or endometrial cancer and carcinoma of the prostate. In metastatic breast cancer, MCA and CA 15.3 showed similar sensitivity. Carcinoembryonic antigen levels did not correlate with MCA. Serum concentrations of MCA increased during pregnancy and remained elevated in nursing mothers. Amniotic fluid was found to be rich in MCA. In contrast, CA 15.3 showed only small changes during pregnancy and was low in amniotic fluid. From binding tests with antibodies used in the MCA and CA 15.3 assays, we conclude that the monoclonal antibodies b-12 as well as 115-D8 and DF3 (CA 15.3 assay) recognize coexisting epitopes on mucin-like antigens, which belong to a polymorphic family of glycoproteins suitable for tumor monitoring. Differences in the behavior of MCA and CA 15.3 may emerge from the complexity and heterogeneity of these mucin-like antigens.

The usefulness of CA15.3, mucin-like carcinoma-associated antigen and carcinoembryonic antigen in determining the clinical course in patients with metastatic breast cancer

“…Bieglmayer et al (1989) also found a similar correlation between these two tumour markers. On the basis of their results from binding tests with the antibodies used in the MCA and CA15.3 assays, they concluded that the monoclonal antibodies b-12 (MCA assay) and 115-D8/DF3 (CA15.3 assay) recognize coexisting epitopes on mucin-like antigens that belong to a number of glycoproteins suitable for tumour monitoring.…”

“…Sensitivity and specificity appear comparable with those of CA15.3 (Bieglmayer et al 1989;Linsley et al 1988;St/ihli et al 1988;de Wit et al 1991;Miserez et al 1991). In order to determine whether these two newly developed markers are more suitable for monitoring, we examined CEA, MCA and CA15.3 levels in the serum of patients with advanced breast cancer and related changes to the clinical course.…”

“…Carcinoembryonic antigen (CEA) is a widely used turnout marker in monitoring patients with advanced metastatic breast cancer (Beard and Haskell 1986;Bieglmayer et al 1989). Changes in elevated CEA levels correlate with changes in disease activity in 33%-85% of patients, the higher percentages having cut-off levels above 20 ng/ml (Beard and Haskell 1986;Colomer et al 1989;Loprinzi et al 1986;Haagensen et al 1978;Tormey and Waalkes 1978;Waalkes et al 1984).…”

“…However, its use is limited by low sensitivity. Elevated levels vary from 35% to 70% in different series (Bieglmayer et al 1989;Haagensen et al 1978;Tormey and Waalkes 1978;Waalkes et al 1984). Routine use of the CEA assay has been discouraged with the contention that it does not lead to more effective treatment (Fletcher 1986).…”

“…Routine use of the CEA assay has been discouraged with the contention that it does not lead to more effective treatment (Fletcher 1986). Recently two new immunoassays for breast cancer have been developed using CA15.3 and mucin-like carcinoma-associated antigen (MCA) (Bieglmayer et al 1989;Hayes et al 1986). The incidence of elevated CA15.3 levels in patients with metastatic breast cancer has been reported to be as high as 80% and therefore this marker may be of value in monitoring the clinical course (Hayes et al 1986).…”