Autoantibodies to MUC1 glycopeptides cannot be used as a screening assay for early detection of breast, ovarian, lung or pancreatic cancer

Abstract

Background: Autoantibodies have been detected in sera before diagnosis of cancer leading to interest in their potential as screening/early detection biomarkers. As we have found autoantibodies to MUC1 glycopeptides to be elevated in early-stage breast cancer patients, in this study we analysed these autoantibodies in large population cohorts of sera taken before cancer diagnosis.

Methods: Serum samples from women who subsequently developed breast cancer, and aged-matched controls, were identified from UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) and Guernsey serum banks to formed discovery and validation sets. These were screened on a microarray platform of 60mer MUC1 glycopeptides and recombinant MUC1 containing 16 tandem repeats. Additional case-control sets comprised of women who subsequently developed ovarian, pancreatic and lung cancer were also screened on the arrays.

Results: In the discovery (273 cases, 273 controls) and the two validation sets (UKCTOCS 426 cases, 426 controls; Guernsey 303 cases and 606 controls), no differences were found in autoantibody reactivity to MUC1 tandem repeat peptide or glycoforms between cases and controls. Furthermore, no differences were observed between ovarian, pancreatic and lung cancer cases and controls.

Conclusion: This robust, validated study shows autoantibodies to MUC1 peptide or glycopeptides cannot be used for breast, ovarian, lung or pancreatic cancer screening. This has significant implications for research on the use of MUC1 in cancer detection.

Figure 1

Autoantibodies to MUC1 in sera from women who subsequently developed breast cancer and matched controls. Dot blots showing the reactivity of autoantibodies present in the discovery sera from women who went on to develop breast cancer (red dots, n=273) and controls (blue dots, n=273), from the UKCTOCS discovery set. The peptide, glycopeptides and glycoproteins (Rec) present on the arrays are indicated beneath each dot plot. The numbers (50, 25, 12·5 and 250, 125, and 62·5) refer to the three concentrations spotted onto the arrays in μℳ for the peptide and glycopeptides, and in pg for the recombinant glycoproteins.

Figure 2

Autoantibodies to MUC1 glycopeptides do not distinguish breast cancer cases from controls. (A, B, C ,D) dot blots showing the reactivity of autoantibodies present in the validation sera from women who went on to develop breast cancer and controls. (A, B) Reactivity on 50 μM of MUC1 core3 glycopeptide; (C, D) Reactivity on 50 μℳ of MUC1STn glycopeptide. (A, C) Sera were identified from the Guernsey serum bank who subsequently developed breast cancer (red dots, n=303), matched controls who were not diagnosed with cancer at the time of diagnosis of the cases (blue dots, n=303) and a second cohort of matched controls consisting of sera from 303 women who had not developed cancer up to 32 years after donation of blood (black dots). (B, D) A second cohort of sera identified from the UKCTOCS bank from women who subsequently developed breast cancer (red dots, n=426) and matched controls (blue dots, n=426). Percentages refer to the percentage of samples giving values higher than two s.d. values above the mean of the controls, and (n) refers to the number of women. (E, F) Receiver operating characteristics of individual and combined features for E, samples from the Guernsey bank and F, samples from UKCTOCS. Solid red lines represent the combination of all MUC1 antigens (see Table 1 for list of antigens) and dotted blue lines represent the individual antigens.

Figure 3

Elevated levels or increased frequency of autoantibodies to MUC1 are not found in sera from ovarian, pancreatic or lung cancer patients before clinical diagnosis. Dot blots showing the reactivity of autoantibodies present in the sera of women who went on to develop lung cancer (green dots, n=123), ovarian cancer (black dots, n=89), pancreatic cancer (magenta dots, n=35) or matched controls (blue dots n=247). The peptide, glycopeptides and glycoproteins (Rec) present on the arrays are indicated beneath each dot blot. The numbers (50, 25, 12·5 and 250, 125, and 62·5) refer to the three concentrations spotted onto the arrays in μℳ for the peptide and glycopeptides, and in pg for the recombinant glycoproteins. Positive samples were defined as samples giving values higher than two s.d. values above the mean of the controls and for MUC1core3 and MUC1STn were as follows: MUC1core3; controls 5.9% positive, pancreatic cancer 5.7% positive, ovarian 3.4% positive, lung 0% positive. MUC1STn; controls 2.3% positive, pancreatic 2.9% positive, ovarian cancer 0%.