A blood test to detect colorectal cancer at an early stage Colorectal cancer (CRC) has a high incidence and mortality rate in European countries. Although early detection significantly improves 5-year survival, it involves highly invasive detection techniques that limit the screening of large populations at risk. Health © Sebastian Kaulitzki, Shutterstock Only 30-40 % of CRC cases are diagnosed at early stages. Current diagnostic methods include complex, expensive or invasive technologies like tomography, magnetic resonance imaging or colonoscopy. To improve CRC screening, the EU-funded Colodetect project developed a novel test that detects and measures cancer-specific autoantibodies present in the blood of patients. “The idea was to develop a test for measuring antibodies generated by the immune system of the patient in response to the tumour,″ explains project coordinator Dr Juan Ignacio Imbaud. Colodetect® relies on ELISA immunoassay technology, which facilitates the simultaneous measurement of 11 cancer-specific autoantibodies from a very small volume of blood sample. Researchers had to overcome several technological challenges associated with sensitivity and detection limit. They transformed singleplex ELISA immunoassays into a multiplex assay using Luminex® technology. Measuring several biomarkers simultaneously in the same sample, this is also faster and more amenable to automation compared to individual assays. Colodetect® was clinically tested and validated in a large and diverse cohort of patients with CRC at different clinical stages. Direct comparison with colonoscopy data demonstrated 81 % sensitivity and 85 % specificity, higher than the commonly used diagnostic faecal occult blood test. The ongoing validation of the test is expected to secure Colodetect® as a marketable in vitro diagnostic product as it is non-invasive, simple and offers accuracy at a reduced cost. The multicentric nature of the project allowed the collection of more than 4 000 samples from CRC patients, healthy individuals with and without confirmatory colonoscopy, and other control samples from patients with other digestive and non-digestive tumours or non-cancer digestive pathologies. According to Dr Imbaud, “this reflects the successful outcome of the collective work of a large number of people from the different participating hospitals, from patients, doctors, and nurses to biobank staff. The cooperation of these people was crucial to validating the test in a real environment.″ Future prospects As Colodetect® detects 11 different autoantibodies, the rationale is to combine the individual readings to provide the physician with a single result on the likelihood that the patient has a CRC or not. For this purpose, partners are in the process of developing mathematical algorithms and software to integrate the analysis and interpretation of the data. Overall, the project has generated a broad portfolio of patents and trademarks in main European countries, Australia and Canada, as well as patent applications in Japan and the United States. Prior to commercialisation, regulatory approval is required, after which it is slated for marketing in Spain in mid-2020. Considering the high prevalence of CRC, there is an imminent need to improve the screening of men and women who are 50-75 years of age as they are at risk of developing CRC to improve patient outcomes with reduced national healthcare costs. Colodetect® is the first diagnostic test that exploits the novel auto-immunity strategy against colon and rectum cancers. Dr Imbaud believes that “the results of the project provide a promising alternative method to efficiently detect CRC at early stages of the disease, with significant benefits in terms of diagnosis and treatment options.″ Keywords Colodetect, colorectal cancer (CRC), blood, autoantibodies, ELISA, tumour, Luminex® technology
