Older men with a novel adult-onset, severe autoinflammatory syndrome known by the acronym VEXAS are likely hiding in plain sight in many adult rheumatology, hematology, and dermatology practices. New clinical features are being described to fill out the clinical profile of such patients who may be currently misdiagnosed with other conditions, according to researchers who first described the syndrome in the last quarter of 2020.
VEXAS is often misdiagnosed as treatment-refractory relapsing polychondritis, polyarteritis nodosa, Sweet syndrome, or giant cell arteritis. These seemingly unrelated disorders are actually tied together by a single thread recently unraveled by David B. Beck, MD, PhD, a clinical fellow at the National Human Genome Research Institute, and colleagues, including rheumatologist Marcela Ferrada, MD, and others at institutes of the National Institute of Health, Bethesda, Md.
The connection between these disparate clinical presentations lies in somatic mutations in UBA1, a gene that initiates cytoplasmic ubiquitylation, a process by which misfolded proteins are tagged for degradation. VEXAS appears primarily limited to men because the UBA1 gene lies on the X chromosome, although it may be possible for women to have it because of an acquired loss of X chromosome.
Leukocytoclastic vasculitis seen in the legs and feet of a man with VEXAS.
VEXAS is an acronym for:
Vacuoles in bone marrow cells
E-1 activating enzyme, which is what UBA1 encodes for
Somatic mutation featuring hematologic mosaicism
Beck said that VEXAS is "probably affecting thousands of Americans," but it is tough to say this early in the understanding of the disease. He estimated that the prevalence of VEXAS could be 1 per 20,000-30,000 individuals.
A New Way of Looking for Disease
VEXAS has caused a major stir among geneticists because of the novel manner in which Beck and his coinvestigators made their discovery. Instead of starting out in the traditional path to discovery of a new genetic disease — that is, by looking for clinical similarities among patients with undiagnosed diseases and then conducting a search for a gene or genes that might explain the shared patient symptoms — the investigators took a genotype-first approach. They scanned the mapped genomic sequences of patients in the National Institutes of Health Undiagnosed Diseases Network, which led them to zero in on mutations in UBA1 as their top candidate.
"We targeted the ubiquitin-proteasome pathway, because it has been implicated in many autoinflammatory diseases – for example, HA20 [A20 haploinsufficiency] and CANDLE syndrome [Chronic Atypical Neutrophilic Dermatosis with Lipodystrophy and Elevated temperature]. Many of these recurrent inflammatory diseases are caused by mutations within this pathway," Beck said in an interview.
Next, they analyzed the genomes of patients in other NIH databases and patients from other study populations at the University College London and Leeds Teaching Hospitals NHS Trust in the United Kingdom in a search for UBA1 somatic mutations, eventually identifying 25 men with the shared features they called VEXAS. These 25 formed the basis for their initial report on the syndrome in the New England Journal of Medicine.
Most autoinflammatory diseases appear in childhood because they stem from germline mutations. VEXAS syndrome, because of somatic mutations with mosaicism, appears to manifest later in life: The median age of the initial 25-man cohort was 64 years, ranging from 45 to 80 years. It's a severe disorder. By the time the investigators were preparing their paper for publication, 10 of the 25 patients, or 40%, had died.
"I think that somatic mutations may account for a significant percentage of severe. adult-onset rheumatologic diseases, and it may change the way we think about treating them based on having a genetic diagnosis," Beck said.
"This approach could be expanded to look at other pathways we know are important in inflammation, or alternatively, it could be completely unbiased and look for any shared variation that occurs across undiagnosed patients with inflammatory diseases. I think that one thing that's important about our study is that previously we had been looking for mutations that really in most cases were the same sort of germline mutations present in [pediatric] patients who have disease at early onset, but now we're thinking about things differently. There may be a different type of genetics that drives adult-onset rheumatologic disease, and this would be somatic mutations which are not present in every cell of the body, just in the blood, and that's why there's just this blood-based disease."
When to Suspect VEXAS Syndrome
Consider the possibility of VEXAS in middle-aged or older men in a rheumatology clinic with characteristics suggestive of treatment-refractory relapsing polychondritis, giant cell arteritis, polyarteritis nodosa, or Sweet syndrome. In the original series of 25 men, 15 were diagnosed with relapsing polychondritis, 8 with Sweet syndrome, 3 with polyarteritis nodosa, and 1 with giant cell arteritis.
Men with VEXAS often have periodic fevers, pulmonary infiltrates, a history of unprovoked venous thromboembolic events, neutrophilic dermatoses, and/or hematologic abnormalities such as myelodysplastic syndrome, multiple myeloma, or monoclonal gammopathy of unknown origin.
Bone marrow biopsy will show vacuoles in myeloid and erythroid precursor cells. Inflammatory marker levels are very high: In the NIH series, the median C-reactive protein was 73 mg/L and median erythrocyte sedimentation rate was 97 mm/hr. The diagnosis of VEXAS can be confirmed by genetic testing performed by Beck and his NIH coworkers (email@example.com).
In interviews, Beck and Ferrada emphasized that management of VEXAS requires a multidisciplinary team of clinicians including rheumatologists, hematologists, and dermatologists.
Ferrada said that rheumatologists could suspect VEXAS in patients who have very high inflammatory markers and do not have a clear diagnosis or do not meet all criteria for other rheumatologic diseases, particularly in older men, but it's possible in younger men as well. Hematologists could also consider VEXAS in patients with macrocytic anemia or macrocytosis without an explanation and inflammatory features, she said.
Ferrada, Beck, and colleagues also published a study in Arthritis & Rheumatology that presents a useful clinical algorithm for deciding whether to order genetic screening for VEXAS in patients with relapsing polychondritis.
First off, Ferrada and colleagues performed whole-exome sequencing and testing for UBA1 variants in an observational cohort of 92 relapsing polychondritis patients to determine the prevalence of VEXAS, which turned out to be 8%. They added an additional 6 patients with relapsing polychondritis and VEXAS from other cohorts, for a total of 13. The investigators determined that patients with VEXAS were older at disease onset, and more likely to have fever, ear chondritis, DVT, pulmonary infiltrates, skin involvement, and periorbital edema. In contrast, the RP cohort had a significantly higher prevalence of airway chondritis, joint involvement, and vestibular symptoms.
Ferrada's algorithm for picking out VEXAS in patients who meet diagnostic criteria for relapsing polychondritis is based upon a few simple factors readily apparent in screening patient charts: male sex; age at onset older than 50 years; macrocytic anemia; and thrombocytopenia. Those four variables, when present, identify VEXAS within an RP cohort with 100% sensitivity and 96% specificity. "As we learn more about [VEXAS] and how it presents earlier, I think we are going to be able to find different manifestations or laboratory data that are going to allow us to diagnose these patients earlier," she said. "The whole role of that algorithm was to guide clinicians who see patients with relapsing polychondritis to test these patients for the mutation, but I think over time that is going to evolve."
Researchers are taking similar approaches for other clinical diagnoses to see which should be referred for UBA1 testing, Beck said.
Myelodysplastic Syndrome and Hematologic Abnormalities
While patients with both myelodysplastic syndrome and relapsing polychondritis have been known in the literature for many years, it's not until now that researchers are seeing a connection between the two, Ferrada said.
A majority of the VEXAS patients in the NEJM study had a workup for myelodysplastic syndrome, but only 24% met criteria. However, many were within the spectrum of myelodysplastic disease and some did not meet criteria because their anemia was attributed to a rheumatologic diagnosis and they did not have a known genetic driver of myelodysplastic syndrome, Beck said. It also fits with this new evidence that UBA1 is probably a driver of myelodysplastic syndrome in and of itself, and that anemia and hematologic involvement are not secondary to the rheumatologic disease; they are linked to the same disease process.
Beck said that there may be a subset of patients who present with primarily hematologic manifestations, noting the NEJM study could have ascertainment bias because the researchers analyzed mainly patients presenting to their clinic with relapsing polychondritis and severe inflammation. NIH researchers also are still looking in their cohort for any association with hematologic malignancies that preceded clinical manifestations, he said.
More Cases Reported
As of early April, another 27 cases had been reported in the literature as more researchers have begun to look for patients with UBA1 mutations, some with additional presenting clinical features associated with VEXAS, including chronic progressive inflammatory arthritis, Kikuchi-Fujimoto disease, spondyloarthritis, and bacterial pneumonia.
"Many times with rare diseases, we can't get enough patients to understand the full spectrum of the disease, but this disease seems to be far more common than we would have expected. We're actually getting many referrals," Beck said.
It appears so far that the range of somatic UBA1 mutations that have been discovered in VEXAS patients does make a difference in the severity of clinical presentation and could potentially be useful in prognosis, Beck said.
Right now, NIH researchers are asking patients about their natural clinical course, assessing disease activity, and determining which treatments get a response, with the ultimate goal of a treatment trial at the NIH.
Developing better treatments for VEXAS syndrome is a priority. In the initial report on VEXAS, the researchers found that the only reliably effective therapy is high-dose corticosteroids.
Ferrada said that NIH investigators have begun thinking about agents that target both the hematologic and inflammatory features of VEXAS. "Most patients get exposed to treatments that are targeted to decrease the inflammatory process, and some of these treatments help partially but not completely to decrease the amount of steroids that patients are taking. For example, one of the medications is tocilizumab. [It was used in] patients who had previous diagnosis of relapsing polychondritis, but they still had to take steroids and their hematologic manifestations keep progressing. We're in the process of figuring out medications that may help in treating both." Ferrada added that because the source of the mutation is in the bone marrow, transplantation may be an effective option.
Laboratory work to identify potential treatments for VEXAS in studies of model organisms could identify treatments outside of the classic anti-inflammatory agents, such as targeting certain cell types in the bone marrow or the ubiquitin-proteasome pathway, Beck said. "We think that however UBA1 works to initiate inflammation may be important not just in VEXAS but in other diseases. Rare diseases may be informing the mechanisms in common diseases."
The VEXAS NEJM study was sponsored by the NIH Intramural Research Programs and by an EU Horizon 2020 Research and Innovation Program grant. Beck reported a patent pending on "Diagnosis and Treatment of VEXAS with Mosaic Missense Mutations in UBA1."
This article originally appeared on MDedge.com, part of the Medscape Professional Network.
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Cite this: VEXAS: A Novel Rheumatologic, Hematologic Syndrome That's Making Waves - Medscape - Apr 08, 2021.