Objective and noninvasive biochemical markers in rheumatoid arthritis: where are we and where are we going?

ABSTRACT

Introduction

Rheumatoid arthritis (RA) is a chronic autoimmune disease that affects approximately 1% of the adult population. RA is multi-factorial, and as such our understanding of the molecular pathways involved in the disease is currently limited. An increasing number of studies have suggested that several molecular phenotypes (i.e. endotypes) of RA exist, and that different endotypes respond differently to various treatments. Biochemical markers may be an attractive means for achieving precision medicine, as they are objective and easily obtainable.

Areas covered

We searched recent publications on biochemical markers in RA as either diagnostic or prognostic markers, or as markers of disease activity. Here, we provide a narrative overview of different classes of markers, such as autoantibodies, citrulline products, markers of tissue turnover and cytokines, that have been tested in clinical cohorts or trials including RA patients.

Expert opinion

Although many biochemical markers have been identified and tested, few are currently being used in clinical practice. As more treatment options are becoming available, the need for precision medicine tools that can aid physicians and patients in choosing the right treatment is growing.

KEYWORDS:

• Rheumatoid arthritis
• biochemical markers
• endotypes
• precision medicine

ARTICLE HIGHLIGHTS

• RA is a chronic, autoimmune condition with a heterogenous profile, meaning that there is a need for biomarkers that can be used to characterise patient subgroups and monitor treatment response.

• Several blood-based biochemical markers have been tested for this purpose during the last two decades, ranging from autoantibodies to post-translational protein modifications and markers reflecting tissue degradation and formation, in addition to inflammatory factors, such as cytokines.

• Although hundreds of markers, some of which are described in this review, have been tested, few are currently used in common practice, and even fewer have been qualified as diagnostic tools for the above purposes.

• THUS, THE CHALLENGE REMAINS: CAN WE IDENTIFY MARKERS THAT MAY BE USED FOR THE APPLICATIONS DESCRIBED BY THE BEST WORK GROUP: DIAGNOSTIC, MONITORING, PHARMACODYNAMICS, PREDICTIVE, PROGNOSTIC, SAFETY, AND RISK?

Declaration of interest

At the time of completion of this manuscript A.C. Bay-Jensen, C.S. Thudium, Anne Sofie Siebuhr and J.H. Mortensen were employees at Nordic Bioscience, a privately owned biomarker company. A.C. Bay-Jensen holds shares in Nordic Bioscience. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.