Faculty Bibliography

OBJECTIVE:Vacuoles, E1-ubiquitin-activating enzyme, X-linked, autoinflammatory, somatic (VEXAS) syndrome is a progressive systemic autoinflammatory disorder caused by somatic variants in UBA1 in blood. Previous analyses have shown discordant disease penetrance. In this study, we examine the associations between demographic features and UBA1 variant allele frequency (VAF) with disease manifestations. METHODS:Whole exome sequencing data from 192,584 participants from Geisinger MyCode Community Health Initiative and Mount Sinai BioMe Biobank were analyzed for disease-causing variants in UBA1. Clinical manifestations were analyzed across individuals with the UBA1 variant. RESULTS:Nine UBA1 variants (VAF range 2.9%-79%) in 23 participants (69.6% men) were identified. Cases with high VAF (>20%) developed macrocytic anemia more often (87.5%) than patients with low VAF (≤20%) variants (27%; P = 0.009). Specifically, at the time of genetic testing, 87.5% of high VAF cases had macrocytic anemia compared with 13.3% of low VAF cases (P = 0.001). However, there was no significant difference in the development of anemia or thrombocytopenia (P = 0.53). In two high VAF cases, macrocytosis developed more than five years before the time of sample collection, followed by anemia approximately at the time of sample collection. In one low VAF case with other inflammatory symptoms, macrocytic anemia did not develop until five years after sample collection. CONCLUSION/CONCLUSIONS:VEXAS syndrome disease severity and penetrance increase at higher VAFs. Low VAF cases demonstrate incomplete penetrance, and the disease tends to be milder in those with it. Female individuals are enriched in lower VAFs and have milder symptoms, suggesting a protective role against disease severity. Low VAF cases, especially ≤10%, can be initially asymptomatic and later develop disease.

VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) is a severe adult-onset inflammatory disease caused by somatic mutations that reduce cytoplasmic activity of UBA1, the primary initiating enzyme for ubiquitylation. How this hypomorphic state drives cell-intrinsic immune activation in mature myeloid cells is unknown. Using unbiased multi-omic, biochemical, and cell biological analyses of model systems and patient-derived cells, we show that loss of cytoplasmic UBA1 activity convergently disrupts endoplasmic reticulum-associated degradation (ERAD) and mitochondrial homeostasis. ERAD failure arises from preferential under-charging of ERAD E2 enzymes, explaining hallmark VEXAS features, including ER-derived vacuoles and unfolded protein response activation, and promotes accumulation of the ERAD substrate STING. Simultaneously, mitochondrial dysfunction drives cytosolic leakage of mitochondrial DNA, inducing cGAS-dependent STING signaling and inflammatory cytokine production. STING inhibition or reversal of mitochondrial DNA leakage resolves multi-cytokine inflammation in VEXAS models and patient myeloid cells, establishing the cGAS-STING pathway as a therapeutically actionable vulnerability.

The Ca²⁺ release-activated Ca²⁺ (CRAC) channel mediates store-operated calcium entry (SOCE), a ubiquitous pathway essential for many cell types, including immune cells. Three Orai (Orai1/2/3) proteins constitute the plasma membrane pore-forming units of CRAC channels that are activated by the endoplasmic reticulum (ER) Ca²⁺-sensing STIM1/2 proteins when ER Ca²⁺ stores are depleted. Orai1/2/3 are differentially expressed across primary cells with discernible differences in their structures and biophysical properties. Further, Orai1 has two alternatively translated isoforms: long mammalian-specific Orai1α and the 63-residue shorter Orai1β, which is evolutionarily older and conserved across vertebrates. Whether Orai1α/1β/2/3 produce unique cytosolic Ca²⁺ signatures that bias transcriptional responses through effectors like NFAT is unclear. Here, we used HEK293 cells engineered to express one native Orai isoform and show that all Orai isoforms couple to NFAT1/4 induction. The magnitude of NFAT1/4 induction for each Orai isoform matches that of SOCE, with the following profile: Orai1β>Orai1α>>Orai2>Orai3. Near-native re-expression of either Orai1α or Orai1β in primary murine Orai1 ^-/- CD4⁺ T cells restored SOCE, NFAT activation, cytokine production and promoted near identical transcriptional responses enriched for immune activation pathways. An analysis of genetic and clinical data of human individuals showed that homozygous null mutations selectively abolishing Orai1α are not associated with disease resembling CRAC channelopathy. Primary T cells from individuals homozygous or heterozygous for an Orai1α null mutation showed enhanced, rather than impaired, SOCE and NFAT induction. Our data indicate that NFAT activation and transcriptional outputs are primarily driven by the graded strength of SOCE mediated by each isoform of the Orai quartet.

OBJECTIVE:VEXAS syndrome is characterized by a complex spectrum of inflammatory and hematologic manifestations. Clinical research to identify effective therapies is urgently needed but is hindered by the lack of validated outcome measures. A VEXAS-specific disease activity index (DAI) is an essential tool for reliably capturing changes in disease activity over time, thereby supporting clinical research and informing patient care in this emerging disease. This study aimed to develop a comprehensive DAI to assess disease-related inflammation across affected organ systems in patients with VEXAS syndrome. METHODS:Inflammatory manifestations of VEXAS were previously identified through a systematic literature review and expert input. A multinational expert advisory committee developed the VEXAS-DAI using modified Delphi methodology until consensus (defined as ≥75% concurrence) was reached. Item grading was adapted from the Common Terminology Criteria for Adverse Events (CTCAE) criteria. Scoring criteria were developed based on 158 test cases using the Physician Global Assessment of Inflammation. RESULTS:Consensus on the VEXAS-DAI was achieved after four Delphi rounds. The index assesses inflammatory activity at the time of evaluation across 12 domains: inflammatory rash, chondritis, periorbital, ophthalmologic, joint, pulmonary, cardiovascular, genitourinary, neurological, oral and gastrointestinal, renal, and constitutional symptoms. The total score ranges from 0 to 40. CONCLUSION/CONCLUSIONS:The VEXAS-DAI is a novel instrument designed to quantify active inflammation over time in patients with VEXAS syndrome. Prospective validation within a clinical trial setting is ongoing.

Hypomethylating agents (HMA) and allogeneic hematopoietic stem cell transplantation (alloHSCT) have both demonstrated remissions in VEXAS; however, comparative data is lacking. We conducted a multicenter, retrospective analysis of 66 patients diagnosed with VEXAS syndrome treated with HMA (n = 35) or alloHSCT (n = 31). Baseline characteristics such as genetics, co-morbidities, and performance status were balanced between the groups, except older age in the HMA group. Median follow-up from therapy initiation was 18 months (95% CI: 11-26), and 14 (21%) deaths were reported (alloHSCT n = 3; HMA n = 11). Among all evaluable patients within the alloHSCT cohort, all patients achieved molecular remission, and a substantial proportion of patients discontinued glucocorticoids (58%). In contrast, HMA therapy was associated with lower but meaningful rates of molecular remission (22%) and glucocorticoid discontinuation (6%). In a real-world setting, HMA therapy was associated with a high discontinuation rate related to toxicity or lack of response. On multivariable analysis adjusted for age and Charlson Comorbidity Index, alloHSCT was associated with improved overall survival (HR = 0.20, 95% CI: 0.05-0.81; p = 0.024). This association remained consistent across multiple ancillary sensitivity analyses, including restriction to transplant-eligible patients, patients aged ≤ 75 years, 1:1 matching, and propensity score-based weighted analyses. Although limited by retrospective design, these findings suggest that alloHSCT remains an attractive and potentially curative strategy in selected patients with VEXAS. Prospective validation of these findings is warranted.

VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome is a disorder discovered in 2020 that bridges haematology, immunology and genetics. VEXAS syndrome arises from somatic mutations in UBA1, which encodes an E1 ubiquitin-activating enzyme, acquired in haematopoietic stem cells. These mutations disrupt ubiquitin-dependent protein homeostasis, triggering proteotoxic and inflammatory stress that drives systemic inflammation, cytopenias and clonal haematopoiesis. Clinically, VEXAS syndrome presents predominantly in older men with glucocorticoid-dependent inflammation, neutrophilic dermatoses, chondritis and myelodysplastic features. Diagnosis relies on characteristic clinical features and confirmation of UBA1 mutations. Prognosis is dismal in many patients, and treatment remains largely empirical. Glucocorticoids and cytokine blockade are used to provide transient control over inflammation, and hypomethylating agents aim to eradicate the mutant clone and induce disease remission. Allogeneic stem cell transplantation offers a potential cure. VEXAS syndrome exemplifies a new paradigm linking somatic genetics, inflammation and clonal haematopoiesis, reshaping our understanding of adult-onset inflammatory disease.

VEXAS syndrome is a severe adult-onset autoinflammatory disease caused by somatic mutations in the UBA1 gene, disrupting cytoplasmic ubiquitin-activating enzyme E1 function in hematopoietic progenitors. Its pathogenesis remains poorly understood, particularly the mechanisms by which UBA1 mutations disrupt myeloid cell function in the context of inflammatory stimuli. Here, we combine a genetically engineered THP-1 monocytic model with ex vivo analyses of blood and tissue samples from VEXAS patients to investigate the consequences of the canonical UBA1M41V mutation. We show that UBA1-mutated monocytes exhibit TNF-α-induced cell death, characterized by RIPK1 phosphorylation, and MLKL- and caspase-8-mediated cell death. Importantly, we extend these findings to patient-derived CD14⁺ sorted cells, confirming that these cells undergo aberrant apoptotic and necroptotic cell death. Mechanistically, activation of these cell death pathways appears to be promoted by defective NF-κB-dependent transcriptional responses and reduced cFLIP(L) expression following TNF-α stimulation. UBA1-mutated monocytes also display blunted cytokine responses to Toll-like receptor (TLR) agonists despite preserved TLR expression, linked to an impaired NF-κB response. UBA1M41V-derived macrophages exhibit a pro-inflammatory transcriptional profile with increased chemokine secretion that promotes monocyte recruitment. In addition, these UBA1-mutated macrophages display impaired efferocytosis due to lysosomal dysfunction. Together, these findings reveal a pathogenic axis in VEXAS syndrome linking UBA1 loss of function and defective ubiquitination to RIPK1-mediated inflammatory cell death, impaired antimicrobial signaling, and defective resolution mechanisms. Our study provides novel mechanistic insights into the myeloid dysfunction underlying inflammation and cytopenia in VEXAS and supports the therapeutic targeting of inflammatory cell death pathways.

VEXAS (Vacuoles, E1 ubiquitin-activating enzyme, X-linked, Autoinflammatory, Somatic) syndrome is a systemic disorder characterized by an overlap of hematologic and inflammatory features. Most patients require chronic use of moderate-to-high doses of glucocorticoids (GCs) to maintain disease control. Data on GC-sparing therapies is limited, and there have been no prospective pharmacotherapeutic trials in VEXAS syndrome published to date. Pacritinib, an oral inhibitor of IRAK1, JAK2, and ACVR1, has emerged as a promising therapeutic option for VEXAS syndrome. The PAXIS trial is the first prospective, randomized pharmacotherapeutic study conducted in this rare and severe disease. Utilizing a novel study design and disease-specific endpoints, the trial will evaluate the efficacy and safety of two dose levels of pacritinib compared with placebo in patients with VEXAS syndrome (NCT06782373, EUCTR: 2024-516347-41-00).

OBJECTIVE:VEXAS syndrome is a severe systemic haemato-inflammatory disease with heterogeneous clinical presentations. Most patients experience recurrent inflammatory flares despite anti-inflammatory therapy. The lack of accepted definitions of flare in these patients is preventing development of disease activity tools that are essential for conducting clinical trials. We aimed to develop a consensus definition of a VEXAS flare for use in clinical trials. METHODS:A 9-member international expert advisory committee established a consensus definition of VEXAS flare using modified Delphi methodology. Clinical inflammatory manifestations of VEXAS syndrome were identified through a systematic literature review. Committee members developed a conceptual framework for flare definition, proposed revisions, and voted on changes until consensus (≥75% concurrence) was reached. RESULTS:Consensus defined VEXAS flare as active inflammatory manifestation(s) of VEXAS syndrome requiring escalation in glucocorticoid therapy. Three flare categories were established: A) recurrence of a prior documented VEXAS manifestation; B) development of a new VEXAS-defining inflammatory manifestation; or C) emergence of a new inflammatory manifestation not meeting criteria for A or B. The panel endorsed an independent adjudication committee to assess Category C flares in clinical trials. CONCLUSIONS:This study proposes a standardized definition of VEXAS flare, providing uniform criteria for identifying VEXAS disease activity. Future research will evaluate its performance in clinical trials.