Exagen Launches Test for Rapid Diagnosis, Differentiation of AAV Subtypes

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by Forest Ray PhD |

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Exagen, a life sciences company developing tests for the diagnosis, prognosis, and monitoring of autoimmune conditions, has launched a new test for the rapid diagnosis of ANCA-associated vasculitis (AAV).

Named AVISE Vasculitis AAV, the test measures for a panel of biomarkers, each of which helps determine the presence of ANCA antibodies — self-targeting antibodies that damage small vessels and cause AAV. The test also can determine the kind of ANCAs a patient has.

This allows researchers to diagnose all three AAV subtypes: granulomatosis with polyangiitis or GPA, microscopic polyangiitis or MPA, and eosinophilic granulomatosis with polyangiitis or EGPA.

“AVISE Vasculitis AAV exemplifies the rigorous quality that is at the core of all AVISE testing products,” Ron Rocca, president and CEO of Exagen, said in a press release.

“As a company dedicated to autoimmune diseases, this test is yet another example of just how closely Exagen is listening to rheumatologists while advancing our ‘own the hilltop’ strategy by providing diagnostic, prognostic, and monitoring tests to address high unmet needs,” he added.

AAV is a type of autoimmune disease that causes small blood vessels to swell and inflame (vasculitis). This is mostly caused by autoantibodies, called anti-neutrophilic cytoplasmic autoantibodies, or ANCAs.

ANCAs are self-reactive antibodies that attack a certain type of immune cell, known as neutrophils, making them attach and produce substances that are toxic to blood vessels.

The early signs and symptoms of AAV and its subtypes can vary widely. Coupled with the disease’s rarity, medical practitioners can find it challenging to make an accurate diagnosis. Difficulties in diagnosis can lead to delays in treatment for patients.

The newly launched test aims to improve the diagnosis of AAV by detecting the presence of ANCAs in the blood. In addition to measuring the levels of known ANCAs, it also examines where in the neutrophils those ANCAs are bound.

While ANCAs in the cytoplasm are more often associated with GPA, the detection of ANCAs close to the nucleus likely indicates a diagnosis of MPA. ANCAs close to the nucleus also are found in 40% of EGPA patients, who can sometimes have ANCAs inside the nucleus as well — an atypical ANCA localization.

The same is true for ANCA types. While those targeting the proteinase 3 protein are primarily associated with GPA, anti-myeloperoxidase ANCAs are mostly associated with MPA.

The test additionally measures for ANCA antibodies targeting the glomerular basement membrane protein, which are associated with diseases other than AAV, and aid in the differential diagnosis of such conditions.

The Vasculitis AAV test adds to Exagen’s catalog of AVISE tests, all aimed at the diagnosis, prognosis, and monitoring of autoimmune diseases.

The AVISE line includes diagnostic tests for lupus and antiphospholipid syndrome, as well as for distinguishing between rheumatoid arthritis, systemic lupus erythmatosus (SLE), fibromyalgia, Sjögren’s syndrome, and scleroderma, among others.

Prognostic and monitoring tests help physicians identify potentially high-risk patients and aid them in keeping an eye on these individuals’ conditions as they evolve.