Utility of the AVISE Connective Tissue Disease test in predicting lupus diagnosis and progression

Complement as a Biomarker for Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a disease of immune complex deposition; therefore, complement plays a vital role in the pathogenesis of SLE. In general, complement levels in blood and complement deposition in histological tests are used for the management of SLE. Thus, the evaluation of complement status can be useful in the diagnosis of SLE, assessment of disease activity, and prediction of treatment response and prognosis. In addition, novel complement biomarkers, such as split products and cell-bound complement activation products, are considered to be more sensitive than traditional complement markers, such as serum C3 and C4 levels and total complement activity (CH50), which become more widely used. In this review, we report the complement testing in the management of SLE over the last decade and summarize their utility.

Autoantibody Discovery, Assay Development and Adoption: Death Valley, the Sea of Survival and Beyond

Dating to the discovery of the Lupus Erythematosus (LE) cell in 1948, there has been a dramatic growth in the discovery of unique autoantibodies and their cognate targets, all of which has led to the availability and use of autoantibody testing for a broad spectrum of autoimmune diseases. Most studies of the sensitivity, specificity, commutability, and harmonization of autoantibody testing have focused on widely available, commercially developed and agency-certified autoantibody kits. However, this is only a small part of the spectrum of autoantibody tests that are provided through laboratories world-wide. This manuscript will review the wider spectrum of testing by exploring the innovation pathway that begins with autoantibody discovery followed by assessment of clinical relevance, accuracy, validation, and then consideration of regulatory requirements as an approved diagnostic test. Some tests are offered as "Research Use Only (RUO)", some as "Laboratory Developed Tests (LDT)", some enter Health Technology Assessment (HTA) pathways, while others are relegated to a "death valley" of autoantibody discovery and become "orphan" autoantibodies. Those that achieve regulatory approval are further threatened by the business world's "Darwinian Sea of Survival". As one example of the trappings of autoantibody progression or failure, it is reported that more than 200 different autoantibodies have been described in systemic lupus erythematosus (SLE), a small handful (~10%) of these have achieved regulatory approval and are widely available as commercial diagnostic kits, while a few others may be available as RUO or LDT assays. However, the vast majority (90%) are orphaned and languish in an autoantibody 'death valley'. This review proposes that it is important to keep an inventory of these "orphan autoantibodies" in 'death valley' because, with the increasing availability of multi-analyte arrays and artificial intelligence (MAAI), some can be rescued to achieve a useful role in clinical diagnostic especially in light of patient stratification and precision medicine.

Finding lupus in the ANA haystack

Diagnosis of SLE in early stages is challenging due to the heterogeneous nature of presenting symptoms and the poor performance metrics of the screening ANA test. Even the more specific double-stranded DNA autoantibody has relatively low predictive value in early disease. A consequence is delayed referral, with the likelihood that some patients have progression of disease prior to specialist evaluation. Tests that might fill this diagnostic gap are therefore needed. The AVISE Connective Tissue Disease Test that uses a multiplex approach to detect autoantibodies and cell-bound complement products has shown utility in distinguishing SLE from other rheumatological conditions. Whether it might be useful in early disease stages to predict progression is addressed in a recent study by Liang and colleagues, who tested clinic patients who had non-specific findings with the objective of determining whether AVISE could predict onset of SLE. While this test provided more useful prognostic information than other available diagnostics, it had relatively low sensitivity, suggesting that significant numbers of patients with preclinical SLE would be missed by this screening. The need remains for development of diagnostics with robust sensitivity and specificity in early disease that would also deliver prognostic information about risk for SLE. Such tests would have great value as a tool for primary providers to more efficiently triage ANA-positive patients for appropriate specialty evaluation.