Reproducibility of autoantibody measurements in normal individuals using the Early CDT-Lung test.

Abstract

e17522 Background: The Early CDT-Lung test is an assay, intended as a tool for risk stratification in a population at high risk for lung cancer. The test measures autoantibodies (AAb) against a panel of six tumor-associated antigens (p53, SOX2, CAGE, NY-ESO-1, GBU4-5 and Annexin 1). The aim of this study was to investigate the variability between repeated samples from the same patient. Methods: Serial serum samples were collected once a week for 4 weeks from premenopausal female smokers (n=46, mean age = 39.9 years) and once every 2 weeks for 4 weeks from post-menopausal female smokers (n=19, mean age = 54.7 years) and male smokers (n=10, mean age=58.4 years). Local ethical approval had been given for the collection. Comparisons between weeks were performed using paired t-tests. Coefficients of variation (CVs) for between-sampling-time (within-patient) reproducibility were compared with historical estimates of between-assay CVs. Results: Paired t-tests showed no significant differences between the paired samples from male smokers. No significant differences were observed between the first sample taken from premenopausal women and any of the subsequent 3 samples. The only significant difference out of 30 t-tests performed was p53 levels in samples from post-menopausal women taken 2 weeks apart (p=0.021). These findings showed that there was no directional trend over time for the patient set while graphics showed constant AAb levels over time within-patient. The comparison of CVs showed that between-sampling-time reproducibility was no higher than that for between-assay CVs for any of the three groups. This confirmed that the within-patient AAb level was not varying over the monthly cycle. Conclusions: The Early CDT-Lung test demonstrates a high degree of reproducibility in measurements of serial samples taken from the same patient. Cyclic hormonal changes do not appear to affect assay results. Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Oncimmune Oncimmune Oncimmune, Oncolytics Biotech, Oncommune Oncimmune