The authors suggest they have developed a biomarker test for schizophrenia based upon a handful of serum measures and one urine metabolite. The properties are said to be equivalent to a diagnostic interview. However, caution is required, and the history suggests so is a healthy dose of skepticism. But if the findings of a perfect test, or even a remotely near-perfect test, are confirmed, and particularly if they apply to very early disease, this will prove to be a landmark paper. Confirmatory studies are essential, which is why I have recommended this paper. View all comments by Michael O'Donovan
The development of biomarkers and the implications of using these to improve diagnostics and clinical trials are becoming more apparent, even for cases of psychiatric disorders such as schizophrenia. The regulatory health authorities now consider biomarkers as important in the pharmaceutical industry, and the Food and Drug Administration (FDA) has called for modernization and standardization of methods, tools, and techniques for the purpose of delivering better and safer drugs (Owens, 2006; Marson, 2007). The FDA has stipulated that molecules must achieve the status of validated biomarkers before they can be used in the regulatory process for clinical trials. This means that biomarkers should be measured in a test system with strict performance characteristics, that there is an established scientific proof of concept to explain the results, and that the test can be replicated with similar results in different laboratories and at different sites.
In the latest Issue of Molecular Psychiatry, Yang and coworkers describe the identification of a composite panel of serum and urine biomarkers which they used to distinguish schizophrenia patients from controls with high accuracy. It should be noted that all of the subjects used in the study were recruited from the Anhui Province of China. This work should be acknowledged as an important early step in the development of biomarkers to help improve the lives of patients with schizophrenia.
However, considerable caution is required before even preliminary steps can be taken towards achieving this goal. First and foremost, the results require replication at multiple sites using different schizophrenia patient cohorts. In addition, the tests will require transfer to a platform which is suitable for use in a clinical environment.
We recently employed an approach based on multiplexed immunoassay profiling, which resulted in identification of a serum signature that could identify schizophrenia patients with an accuracy of 82 percent across five independent patient cohorts, with similar results in subsequent validation studies in different laboratories (Schwarz et al., 2011; Schwarz et al., 2010). This is an automated test that uses a single serum sample to measure approximately 50 molecules simultaneously. It was designed in its first form to help mental health professionals arrive at a diagnosis. This test has now been launched in the U.S. under the trade name VeriPsych as part of a collaboration between Psynova Neurotech in the U.K. and Myriad-RBM in the U.S. The next phase will be to develop a version of the test which can be used to distinguish schizophrenia from other psychiatric disorders with overlapping symptoms. There is now reason for optimism that, with concerted efforts in this field, the application of biomarkers in the field of psychiatric disorders will soon become a reality (Bahn et al., 2011).
Owens J. Funding for accelerating drug development initiative critical. Nat Rev Drug Discov . 2006 Apr 1 ; 5(4):271. Abstract
Marson, B. (2007) ''Critical Path'' is on the road forward; FDA reports industry activity is high. The Pink Sheet. 69; 29.
Schwarz E, Guest PC, Rahmoune H, Harris LW, Wang L, Leweke FM, Rothermundt M, Bogerts B, Koethe D, Kranaster L, Ohrmann P, Suslow T, McAllister G, Spain M, Barnes A, van Beveren NJ, Baron-Cohen S, Steiner J, Torrey FE, Yolken RH, Bahn S. Identification of a biological signature for schizophrenia in serum. Mol Psychiatry . 2011 Apr 12. Abstract
Schwarz E, Izmailov R, Spain M, Barnes A, Mapes JP, Guest PC, Rahmoune H, Pietsch S, Leweke FM, Rothermundt M, Steiner J, Koethe D, Kranaster L, Ohrmann P, Suslow T, Levin Y, Bogerts B, van Beveren NJ, McAllister G, Weber N, Niebuhr D, Cowan D, Yolken RH, Bahn S. Validation of a blood-based laboratory test to aid in the confirmation of a diagnosis of schizophrenia. Biomark Insights . 2010 Jan 1 ; 5():39-47. Abstract
Bahn S, Noll R, Barnes A, Schwarz E, Guest PC. Challenges of introducing new biomarker products for neuropsychiatric disorders into the market. Int Rev Neurobiol . 2011 Jan 1 ; 101():299-327. Abstract
View all comments by Sabine BahnView all comments by Paul C. Guest
This line of work is immensely important, as the lack of reliable biomarkers presents a major barrier to the receipt of a definitive diagnosis and the initiation of treatment; ultimately, the detection of biomarkers that are present at first episode may also signal biomarkers that may be present in the prodrome and even before symptoms emerge, which might provide a basis for earlier intervention and prevention. As elegantly summarized by Drs. Bahn, Guest, and O'Donovan, these results will need replication in diverse samples before they can be capitalized upon in the form of a clinically useful test; however, it does make sense that a biomarker profile derived from multiple sources (serum and urine) might have better explanatory power than a profile derived from just one source. Similarly, the next frontier in the development of biomarker panels may involve what I've called a polyomic approach, taking into account genetic and functional genomic variation as well as metabolite variability as demonstrated here.View all comments by Stephen J. Glatt