Ultrasensitive protein detection and its importance in biomedical diagnostics

by Andrzej Drukier (Nordita and BioTraces Inc. 5660 Oak Tanager Ct., Burke , Va. 22015, USA adrukier@gmail.com)

Tuesday 19 May 2015, 13:30 → 14:30 Europe/Stockholm

122:026

There is a steady advancement of techniques for detecting proteins and other macromolecules. However it is mainly in the 'faster and cheaper” category, whereas the sensitivity of detection is still very limiting. We developed the techniques for protein detection on the level of 1 fg/ml and 20 fg/ml. Our assays, called IA-MPD and Super-ELISA are about 500 and 50-fold more sensitive than best ELISA. We applied our assays in clinical studies targeting panels of bio-markers, from 5 to 10 different targets. We targeted low abundance proteins, such as cytokines, which can be currently detected in only 50-70% of a cohort. We demonstrated sensitivity and specificity of about 95% in a cohort of 600 women with breast cancer (BC) and a similar in size cohort of controls. This is possible even for women with age below 40 years, wherein both MRI and mammography are at a sensitivity/specificity level below 70 %. Thus, we observed about 5-fold improvement of false positives and negatives. Using different bio-markers selected for a disease-specific panel, we applied these methods also to five other cancers and observed better than 90% sensitivity and specificity, though cohort statistics have been lower, from 100-200. Most interesting are the results, which suggest the high value of the ultra-sensitive proteomics for prediction rather than detection of BC. Because we detect the cytokines in almost all (> 95%) of women, we could achieve a good stratification of immune systems of women. We demonstrated that out of 64 possible “immune-boxes” only six have an occupation bigger than 5%; and they accounts for about 80% of all tested women. Three of these are women with “weak” immune systems and two with “very strong “immune systems. Our data suggest that the women with weak immune systems have about 5-10 fold higher probability of breast cancer. However, women with strong immune systems have about 3-fold lower risk for breast cancer. Finally, the immune system is a good example of a “strongly coupled” and “very nonlinear” system. However, in the period of menopause, the character of the immune system changes. It becomes more weakly coupled and semi-linear. This, in our opinion, influences the risk for breast and ovarian cancer. It is in agreement with epidemologic data, which suggests that the probability of onset of BC is highest in the early post-menopausal period.