Colorectal cancer (CRC) is the third most common malignancy in industrialized countries. Despite the advances in diagnostics and development of new drugs, the 5‐year survival remains only 60–65%. Our approach to early diagnostics of CRC is based on the determination of serological signatures with an array of hemispherical hydrogel cells containing immobilized proteins and oligosaccharides (glycochip). The compounds immobilized on the glycochip include tumor‐associated glycans (SiaTn, Tn, TF, LeC, LeY, SiaLeA, and Manβ1‐4GlcNAcβ) and antibodies against human immunoglobulins IgG, IgA, and IgM. The glycochip detects antibodies against tumor‐associated glycans in patients’ sera. The simultaneous measurement of the levels of immunoglobulins enhances the diagnostic impact of the signatures. In this work, we found previously unreported increase in antibodies against oligosaccharide Manβ1‐4GlcNAcβ in patients with CRC. In parallel with these experiments, we determined the levels of oncomarkers carcinoembryonic antigen (CEA), cancer antigen (CA) 19–9, CA 125, CA 15–3, human chorionic gonadotropin (HCG), and alpha‐fetoprotein (AFP) using another gel‐based biochip with immobilized antibodies (oncochip) developed earlier in our laboratory. In total, 69 samples from healthy donors, 33 from patients with colorectal carcinoma, and 27 from patients with inflammatory bowel diseases were studied. The use of combined signatures of antiglycan antibodies and oncomarkers provides much better predictive value than the conventional measurement of oncomarkers CEA and CA 19–9. Positive predictive value of CRC diagnoses using together glycochip and oncochip reached 95% with the sensitivity and specificity 88% and 98%, respectively. Thus, the combination of antibody profiling with detection of conventional oncomarkers proved to be a promising tool in diagnostics of CRC.

The biochip was constructed for simultaneous assay of total and free prostate-specific antigen, alpha-fetoprotein, cancer embryonic antigen, human chorionic gonadotropin, and neuron-specific enolase. These biochips represent an array of gel elements with covalently immobilized proteins. The major analytic characteristics of the developed method were obtained. It was shown that the results of simultaneous assay of six tumor markers in blood serum well correlated with routine measurement of each marker using enzyme immunoassay kits. This approach allowed us to reveal the hook effect of high concentrations during biochip assay, which prevents distortion of the diagnostic picture at high concentration of the analyte in the sample.

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Assay on a biochip provides a simple and accurate procedure for the differential quantitation of SCCA1 and SCCA2.