Telltale Traces in the Blood09/02/2011
A blood test that reliably reveals at an early stage whether a person has contracted a tumour: This is the dream of many a physician. In their quest of such a test, researchers have now taken one step forward. Medical scientists of the Würzburg University Women’s Clinic were also involved.
Ovarian cancer, as many other tumour diseases, meanwhile has a good chance of healing. The only condition: It must be detected as early as possible. Then it can be treated successfully in over 90 per cent of the cases. But due to the fact that the tumour normally does not cause any pain in this early stage, patients often do not see a doctor until late, when the chance of cure is clearly diminished. As for many other diseases, there is currently no reliable early detection method available.
This unsatisfactory situation has led Dr. Sebastian Häusler, associate professor Dr. Jörg Wischhusen and Professor Johannes Dietl of the Würzburg University Women’s Clinic to search for diagnostically usable structures in the blood of tumour patients. Among the so-called microRNAs, they struck a bonanza.
Focussing on tiny molecules
MicroRNAs were first described in 2001. They are small molecules that play an important role in the complex process of gene regulation in the cells. Unlike their relatives, the ribonucleic acids called RNA, they do not encode certain proteins. According to present knowledge, they rather accumulate at certain RNA strands and this way have an indirect effect on the production of protein. Thus, they also participate in many disease and cellular adaptation processes.
For their examinations, the Würzburg scientists used a biomarker concept developed by Dr. Andreas Keller of the Saarland University. It is able to consider the information content of over 100 microRNAs and thus allows an impressive degree of sensitivity, specificity and accuracy. “We were able to prove that specific microRNA signatures are present in the blood of ovarian cancer patients which allow a delimitation to healthy ones”, says Jörg Wischhusen. The results of the study were published last year in the renowned British Journal of Cancer.
One test for 14 diseases
In a follow-up study, scientists from all over Germany have now put the testing procedures to the test on a total of 14 diseases, some of which are difficult to diagnose. They include tumour diseases of the pancreas, the prostate or the gastro-intestinal tract as well as multiple sclerosis and chronically obstructive pulmonary diseases. This study was coordinated by the Heidelberg-based “Biomarker Discovery Center”, also under the leadership of Andreas Keller; the Würzburg scientists contributed research in their area of expertise – the ovarian cancer.
The result gives rise to hope: “The hit rate was very high in many cases”, says Jörg Wischhusen. In some of the clinical pictures, it was over 99 per cent. In the case of ovarian cancer, it was beyond 90 per cent. “Measured against the tests that have existed so far, this is a very good outcome”, says the scientist. The results of this study are currently presented in a report on the homepage of the renowned journal Nature Methods.
Further analyses are necessary
The test is said to have shown “a high specificity for the individual clinical pictures that can be diagnostically well differentiated from each other and from healthy control groups”. The scientists now hope to be able to diagnose a multitude of diseases with a high level of reliability by using a single blood test. However, it may be quite some time until then: “It will take a lot of more work, a great deal of money and further studies until a marketable product indeed obtains the approval“, Wischhusen believes. The Heidelberg company febit at least is working on it.
„Towards discovering the blood-borne miRNome of human diseases“, Andreas Keller, Joerg Wischhusen, Sebastian F. M. Häusler, Johannes Dietl et al., Nature Methods Online
PD Dr. Jörg Wischhusen, T +49 (0)931 201-25291, e-mail: Wischhusen_J@klinik.uni-wuerzburg.de