18 July 2014

Early diagnosis of cancer and other diseases: immunoprofiling

Despite the impressive achievements of science, cancer remains one of the main causes of death, and its treatment is a heavy financial burden for healthcare in all countries of the world. Experts believe that one of the key approaches to solving the problem of cancer is its timely diagnosis, but so far the search for biomarkers of the early stages of the disease has been complicated by many factors.

Researchers at Arizona State University, working under the leadership of Professor Stephen Albert Johnston, managed to develop a promising technology for early detection of cancer, called "immunoprofiling" (immunosignaturing).

To date, only a few cancer biomarkers have been approved by the U.S. Food and Drug Administration for clinical use. However, even these markers do not always provide reliable information. This is due to a number of reasons. The body's immune response to cancer is very complex, heterogeneous and varies from patient to patient, as well as depending on the type and stage of the disease. When used individually, biomarkers do not have sensitivity sufficient to make a decision about a positive diagnosis. At the same time, diagnostic molecules such as RNA, DNA, proteins and peptides are often present in the bloodstream in negligible quantities, which makes it difficult to quantify and qualitatively determine their content.

Immunoprofiling is a fundamentally new approach to solving the problem, which consists in using an integrated system that provides profiling of the entire population of antibodies circulating in the patient's blood. This is done using a microchip – a glass plate, on the surface of which its 10,000 oligopeptides are deposited, consisting of random sequences of 20 amino acids.

When a tiny drop of blood (less than a microliter) is distributed over the surface of the microchip, the antibodies contained in it selectively bind to individual peptides, forming a "portrait" of immune activity – an immune profile.

Stephen Johnston undoubtedly understands what the differences between these two immune profiles mean :)

Since the peptide sequences are formed randomly and have nothing to do with the antigens of any diseases, this platform can be used to diagnose multiple pathologies simultaneously.

As part of their study, the authors first used 120 blood samples (20 samples from each of the 5 cohorts of cancer patients with known diagnoses and 20 blood samples of healthy people) to determine control immune profiles – "portraits" of immune activity characteristic of healthy people and the five types of cancer analyzed. After that, the system was tested blindly on 120 independent blood samples of patients with similar diagnoses. The accuracy of the results was 95%.

To further evaluate the diagnostic power of immunoprofiling, the authors tested it on more than 1,500 preserved blood samples of patients with 14 diseases, including 12 types of cancer. At the same time, 75% of the samples were used to determine control profiles and 25% for blind testing. In this case, the diagnostic efficiency exceeded 98%.

The researchers are currently working on further improving the sensitivity and accuracy of the new technology. To do this, they plan to apply more than 100,000 peptides to the surface of the microchip.

The article by Phillip Stafford et al. Immunosignature system for diagnosis of cancer is published in the journal Proceedings of the National Academy of Science.

Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of Arizona State University:
Capturing cancer: a powerful new technique for early diagnosis


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