RARE DISEASE
Microscopic polyangiitis
Microscopic polyangiitis
Microscopic polyangiitis
Synonyms: MPA, Micropolyangiitis, Microscopic polyarteritis
Synonyms: MPA, Micropolyangiitis, Microscopic polyarteritis
Synonyms: MPA, Micropolyangiitis, Microscopic polyarteritis
Drug discovery
1
drug
With orphan designation
Overview
Microscopic polyangiitis (MPA) is a systemic ANCA-associated vasculitis primarily affecting small vessels, with renal (pauci-immune glomerulonephritis) and pulmonary (alveolar hemorrhage) involvement being hallmarks. Diagnosis relies on ANCA serology (MPO-ANCA positivity in 60%), tissue biopsy, and exclusion of granulomatous disease. Initial treatment combines glucocorticoids with rituximab or cyclophosphamide for induction, followed by maintenance immunosuppression. Despite improved survival, relapses occur in 20-40%, and chronic kidney disease remains a major complication [1][2][6][9][16].
Categories: rare circulatory system diseases, rare neurological diseases, rare renal diseases, rare respiratory diseases, rare systemic and rheumatological diseases, rare systemic or rheumatologic diseases of childhood, rare transplant-related disorders
Research Papers
1,065 drug discovery papers about Microscopic polyangiitis, with 2 first-in-class and 6 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
1,065 drug discovery papers about Microscopic polyangiitis, with 2 first-in-class and 6 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
2026-07-31 | Biosimilar Rituximab in ANCA-Associated Vasculitis Compared to the Originator: A Multicenter Cohort Study.
To evaluate the six-month effectiveness and safety of rituximab biosimilars compared to the originator in granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA), and outcomes following originator to biosimilar switching. We recruited adults with GPA or MPA treated with the rituximab originator or a biosimilar for induction or maintenance, or who switched from originator to biosimilar maintenance (2018-2023). Participants either started the treatment within the preceding six months or were recruited from vasculitis research cohorts. Outcomes included six-month remission (Birmingham Vasculitis Activity Score [BVAS] version 3 of 0), relapse (BVAS rise after achieving remission requiring treatment), vasculitis damage, and serious adverse events (SAEs). We studied 207 participants from 9 centers: 132 starting induction (58 originator and 74 biosimilar), 59 starting maintenance (23 originator and 36 biosimilar), and 16 in the "switch" group. Mean age was 56.7 years (SD 17.5), 52% were female, 80% were White, and 70% had GPA. At six months from induction, 51 of 53 (96%) originator and 66 of 73 (90%) biosimilar recipients achieved remission (difference 6%, 95% confidence interval [CI] -4% to 15%), whereas at three months (exploratory) 48 of 51 (94%) and 57 of 72 (79%) recipients, respectively, had achieved remission (difference 15%, 95% CI 2% to 26%). All individuals in the maintenance and "switch" subgroups were in remission at six months. One minor relapse occurred in each of the induction groups and in the originator maintenance group. Change in vasculitis damage and SAEs were not significantly different between groups. This study found no significant differences in six-month outcomes between the rituximab originator and biosimilars for induction of GPA and MPA, with no concerning early signals in those initiating maintenance or switching from the originator to a biosimilar.
2026-07-28 | Advances in the Diagnosis, Treatment and Prognosis of ANCA-Associated Glomerulonephritis.
ANCA-associated vasculitis (AAV) with kidney involvement represents small-vessel vasculitis, characterized by rapidly progressive glomerulonephritis and a high risk of end-stage kidney disease (ESKD) and increased mortality. AAV typically presents with multisystem involvement, with renal manifestations occurring more frequently in microscopic polyangiitis (MPA) (90-100%) and granulomatosis with polyangiitis (GPA) (50-80%). The classic clinical presentation includes acute kidney injury with hematuria and proteinuria, accompanied by ANCA positivity (MPO-ANCA or PR3-ANCA). Histologically, the predominant pattern is segmental necrotizing glomerulonephritis with crescent formation. Treatment consists of two phases: (a) induction of remission with a lower cumulative dose of glucocorticoids (according to the reduced-dose PEXIVAS regimen) in combination with rituximab or cyclophosphamide and (b) maintenance of remission with rituximab for 2-4 years. The C5a receptor inhibitor avacopan can be used as a steroid-sparing agent in patients with severe kidney involvement or at high risk of corticosteroid-related complications. Beyond the traditional markers of disease activity (hematuria, proteinuria, eGFR), novel biomarkers such as urinary soluble CD163, MCP-1, complement activation products (C5a, sC5b-9), and urinary Treg/Th17 profiles have demonstrated prognostic value. Early diagnosis and prompt initiation of immunosuppressive therapy significantly improve both kidney and overall survival, while prevention of relapses and long-term complications plays a key role in improving the long-term prognosis of patients with AAV.
2026-07-16 | Developing a prediction model for poor prognosis in MPA patients using initial admission examination results: a machine learning study from Southwest China.
Microscopic polyangiitis (MPA) is one of the main types of ANCA-associated vasculitis (AAV), but current admission examination indicators are limited in predicting poor prognosis for MPA. This study aims to develop a prediction model for adverse prognosis in MPA patients using initial admission examination results. We performed machine learning (ML) algorithms on initial admission examination data to predict adverse outcomes in MPA, such as in-hospital death or self-discharge due to critical condition. We analyzed data from 12,497 patients who underwent ANCA tests in Deyang People's Hospital between November 2017 and October 2025, focusing on 230 hospitalized patients. We used least absolute shrinkage and selection operator (LASSO), logistic regression (LR), and random forest (RF) to select variables, and evaluated the diagnostic efficacy using ML algorithms. SHapley Additive exPlanations (SHAP) was used for model interpretability. A nomogram model was developed to predict adverse outcomes, highlighting variable contributions and including calibration and decision curve analysis (DCA) curves. In this study of 230 MPA patients, 56 had poor prognosis while 174 had good prognosis. Seven indicators were identified using LASSO, LR and RF. They were appropriate use of immunosuppressants, age, serum albumin, infection, BVAS, C-reactive protein (CRP) and anti- myeloperoxidase. Among five ML models, support vector classification (SVC) had a high area under the curve (AUC) (AUC = 0.848, 95% confidence interval [CI]: 0.684-0.965) in the prediction model, and had the highest AUC (AUC = 0.886, 95% CI: 0.741-0.981). The SHAP analysis highlighted elevated CRP levels as the top predictor of poor prognosis. Standardized immunosuppressive therapy was found to mitigate this risk. Nomogram model confirmed these findings, and calibration and DCA curves showed this model was reliable and useful for clinical decisions. We developed a prediction model for adverse outcomes in MPA patients, utilizing clinical and laboratory data collected on the day of admission. SVC algorithm exhibited moderate predictive efficacy. Factors such as elevated serum CRP levels, moderate reductions in serum albumin, infection, advanced age, BVAS larger than 15, and anti-MPO were positively associated with adverse prognoses. Standardized immunosuppressive therapy was shown to mitigate this risk, offering a valuable reference for clinical decision-making.
2026-07-06 | Real-world retention of nintedanib and factors associated with treatment discontinuation in connective tissue disease-associated interstitial lung disease: a retrospective cohort study of 92 patients.
Treatment discontinuation of nintedanib is an important clinical issue in patients with connective tissue disease-associated interstitial lung disease (CTD-ILD). This study aimed to evaluate real-world retention of nintedanib across CTD subtypes and to explore factors associated with treatment discontinuation. We conducted a single-center retrospective study of consecutive patients with CTD-ILD who initiated nintedanib between June 2019 and December 2024. Clinical data, including baseline characteristics, concomitant therapies, and treatment outcomes, were collected. The primary outcome was the 48-week retention rate. Kaplan-Meier analysis and Cox proportional hazards models were used to evaluate factors associated with treatment discontinuation. A total of 92 patients were included (rheumatoid arthritis [RA], n = 25; idiopathic inflammatory myopathy [IIM], n = 25; systemic sclerosis [SSc], n = 21; microscopic polyangiitis [MPA], n = 10; Sjögren disease [SjD], n = 9). The 48-week retention rate was 82.6%, with a median treatment duration of 978 days (IQR, 586-1356). Retention was lowest in RA, with higher rates observed in other CTD subtypes. Stratified analyses showed that this difference was evident in patients aged < 65 years (p = 0.001) and those receiving an initial dose of 300 mg/day (p = 0.003), but not in older patients or those receiving < 300 mg/day. In univariable analysis, RA (HR 3.10, p = 0.024) and an initial dose of 300 mg/day (HR 2.67, p = 0.050) were associated with discontinuation. However, RA was not independently associated with discontinuation after adjustment for age and initial dose in the exploratory multivariable analysis. Nintedanib showed favorable retention in CTD-ILD. Although retention appeared lower in RA, this difference may be influenced by patient characteristics such as age and initial dosing. Individualized dose selection and appropriate management of adverse events may improve treatment persistence. Key Points • Nintedanib showed favorable 48-week retention in patients with CTD-ILD in a real-world setting. • Lower retention observed in RA was influenced by age and initial dosing, rather than disease subtype alone.
2026-07-06 | Microscopic Polyangiitis With Temporal Artery Involvement Mimicking Giant Cell Arteritis.
A 63-year-old woman presented with a four-month history of bilateral hearing loss and three months of progressive, painful peripheral neuropathy. Her clinical course was complicated by deep vein thrombosis with pulmonary emboli and an incomplete response to initial empiric glucocorticoid therapy. Following glucocorticoid taper, she developed temporal headaches, jaw claudication, and scalp tenderness, raising concern for giant cell arteritis (GCA). Laboratory evaluation revealed markedly elevated inflammatory markers (erythrocyte sedimentation rate and C-reactive protein), microcytic anemia, mild hematuria, and strongly positive myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA) by antigen-specific immunoassay with negative proteinase-3 (PR3)-ANCA. Temporal artery biopsy demonstrated transmural inflammation affecting all vessel layers without giant cells or granulomata. The combination of multisystem small-vessel involvement, MPO-ANCA seropositivity with negative PR3-ANCA, and characteristic histopathological findings established the diagnosis of microscopic polyangiitis (MPA) with temporal arteritis rather than granulomatosis with polyangiitis (GPA) or GCA. Treatment with high-dose glucocorticoids (prednisone 80 mg daily), avacopan (30 mg twice daily), and rituximab (375 mg/m² weekly for four weeks) resulted in rapid improvement of constitutional and cranial symptoms. This case highlights the importance of integrating MPO-ANCA serology and histopathological findings when temporal arteritis is the presenting feature of systemic vasculitis. It illustrates the utility of avacopan-based, glucocorticoid-sparing combination immunosuppression in this context.
2026-07-31 | Biosimilar Rituximab in ANCA-Associated Vasculitis Compared to the Originator: A Multicenter Cohort Study.
To evaluate the six-month effectiveness and safety of rituximab biosimilars compared to the originator in granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA), and outcomes following originator to biosimilar switching. We recruited adults with GPA or MPA treated with the rituximab originator or a biosimilar for induction or maintenance, or who switched from originator to biosimilar maintenance (2018-2023). Participants either started the treatment within the preceding six months or were recruited from vasculitis research cohorts. Outcomes included six-month remission (Birmingham Vasculitis Activity Score [BVAS] version 3 of 0), relapse (BVAS rise after achieving remission requiring treatment), vasculitis damage, and serious adverse events (SAEs). We studied 207 participants from 9 centers: 132 starting induction (58 originator and 74 biosimilar), 59 starting maintenance (23 originator and 36 biosimilar), and 16 in the "switch" group. Mean age was 56.7 years (SD 17.5), 52% were female, 80% were White, and 70% had GPA. At six months from induction, 51 of 53 (96%) originator and 66 of 73 (90%) biosimilar recipients achieved remission (difference 6%, 95% confidence interval [CI] -4% to 15%), whereas at three months (exploratory) 48 of 51 (94%) and 57 of 72 (79%) recipients, respectively, had achieved remission (difference 15%, 95% CI 2% to 26%). All individuals in the maintenance and "switch" subgroups were in remission at six months. One minor relapse occurred in each of the induction groups and in the originator maintenance group. Change in vasculitis damage and SAEs were not significantly different between groups. This study found no significant differences in six-month outcomes between the rituximab originator and biosimilars for induction of GPA and MPA, with no concerning early signals in those initiating maintenance or switching from the originator to a biosimilar.
2026-07-28 | Advances in the Diagnosis, Treatment and Prognosis of ANCA-Associated Glomerulonephritis.
ANCA-associated vasculitis (AAV) with kidney involvement represents small-vessel vasculitis, characterized by rapidly progressive glomerulonephritis and a high risk of end-stage kidney disease (ESKD) and increased mortality. AAV typically presents with multisystem involvement, with renal manifestations occurring more frequently in microscopic polyangiitis (MPA) (90-100%) and granulomatosis with polyangiitis (GPA) (50-80%). The classic clinical presentation includes acute kidney injury with hematuria and proteinuria, accompanied by ANCA positivity (MPO-ANCA or PR3-ANCA). Histologically, the predominant pattern is segmental necrotizing glomerulonephritis with crescent formation. Treatment consists of two phases: (a) induction of remission with a lower cumulative dose of glucocorticoids (according to the reduced-dose PEXIVAS regimen) in combination with rituximab or cyclophosphamide and (b) maintenance of remission with rituximab for 2-4 years. The C5a receptor inhibitor avacopan can be used as a steroid-sparing agent in patients with severe kidney involvement or at high risk of corticosteroid-related complications. Beyond the traditional markers of disease activity (hematuria, proteinuria, eGFR), novel biomarkers such as urinary soluble CD163, MCP-1, complement activation products (C5a, sC5b-9), and urinary Treg/Th17 profiles have demonstrated prognostic value. Early diagnosis and prompt initiation of immunosuppressive therapy significantly improve both kidney and overall survival, while prevention of relapses and long-term complications plays a key role in improving the long-term prognosis of patients with AAV.
2026-07-16 | Developing a prediction model for poor prognosis in MPA patients using initial admission examination results: a machine learning study from Southwest China.
Microscopic polyangiitis (MPA) is one of the main types of ANCA-associated vasculitis (AAV), but current admission examination indicators are limited in predicting poor prognosis for MPA. This study aims to develop a prediction model for adverse prognosis in MPA patients using initial admission examination results. We performed machine learning (ML) algorithms on initial admission examination data to predict adverse outcomes in MPA, such as in-hospital death or self-discharge due to critical condition. We analyzed data from 12,497 patients who underwent ANCA tests in Deyang People's Hospital between November 2017 and October 2025, focusing on 230 hospitalized patients. We used least absolute shrinkage and selection operator (LASSO), logistic regression (LR), and random forest (RF) to select variables, and evaluated the diagnostic efficacy using ML algorithms. SHapley Additive exPlanations (SHAP) was used for model interpretability. A nomogram model was developed to predict adverse outcomes, highlighting variable contributions and including calibration and decision curve analysis (DCA) curves. In this study of 230 MPA patients, 56 had poor prognosis while 174 had good prognosis. Seven indicators were identified using LASSO, LR and RF. They were appropriate use of immunosuppressants, age, serum albumin, infection, BVAS, C-reactive protein (CRP) and anti- myeloperoxidase. Among five ML models, support vector classification (SVC) had a high area under the curve (AUC) (AUC = 0.848, 95% confidence interval [CI]: 0.684-0.965) in the prediction model, and had the highest AUC (AUC = 0.886, 95% CI: 0.741-0.981). The SHAP analysis highlighted elevated CRP levels as the top predictor of poor prognosis. Standardized immunosuppressive therapy was found to mitigate this risk. Nomogram model confirmed these findings, and calibration and DCA curves showed this model was reliable and useful for clinical decisions. We developed a prediction model for adverse outcomes in MPA patients, utilizing clinical and laboratory data collected on the day of admission. SVC algorithm exhibited moderate predictive efficacy. Factors such as elevated serum CRP levels, moderate reductions in serum albumin, infection, advanced age, BVAS larger than 15, and anti-MPO were positively associated with adverse prognoses. Standardized immunosuppressive therapy was shown to mitigate this risk, offering a valuable reference for clinical decision-making.
2026-07-06 | Real-world retention of nintedanib and factors associated with treatment discontinuation in connective tissue disease-associated interstitial lung disease: a retrospective cohort study of 92 patients.
Treatment discontinuation of nintedanib is an important clinical issue in patients with connective tissue disease-associated interstitial lung disease (CTD-ILD). This study aimed to evaluate real-world retention of nintedanib across CTD subtypes and to explore factors associated with treatment discontinuation. We conducted a single-center retrospective study of consecutive patients with CTD-ILD who initiated nintedanib between June 2019 and December 2024. Clinical data, including baseline characteristics, concomitant therapies, and treatment outcomes, were collected. The primary outcome was the 48-week retention rate. Kaplan-Meier analysis and Cox proportional hazards models were used to evaluate factors associated with treatment discontinuation. A total of 92 patients were included (rheumatoid arthritis [RA], n = 25; idiopathic inflammatory myopathy [IIM], n = 25; systemic sclerosis [SSc], n = 21; microscopic polyangiitis [MPA], n = 10; Sjögren disease [SjD], n = 9). The 48-week retention rate was 82.6%, with a median treatment duration of 978 days (IQR, 586-1356). Retention was lowest in RA, with higher rates observed in other CTD subtypes. Stratified analyses showed that this difference was evident in patients aged < 65 years (p = 0.001) and those receiving an initial dose of 300 mg/day (p = 0.003), but not in older patients or those receiving < 300 mg/day. In univariable analysis, RA (HR 3.10, p = 0.024) and an initial dose of 300 mg/day (HR 2.67, p = 0.050) were associated with discontinuation. However, RA was not independently associated with discontinuation after adjustment for age and initial dose in the exploratory multivariable analysis. Nintedanib showed favorable retention in CTD-ILD. Although retention appeared lower in RA, this difference may be influenced by patient characteristics such as age and initial dosing. Individualized dose selection and appropriate management of adverse events may improve treatment persistence. Key Points • Nintedanib showed favorable 48-week retention in patients with CTD-ILD in a real-world setting. • Lower retention observed in RA was influenced by age and initial dosing, rather than disease subtype alone.
2026-07-06 | Microscopic Polyangiitis With Temporal Artery Involvement Mimicking Giant Cell Arteritis.
A 63-year-old woman presented with a four-month history of bilateral hearing loss and three months of progressive, painful peripheral neuropathy. Her clinical course was complicated by deep vein thrombosis with pulmonary emboli and an incomplete response to initial empiric glucocorticoid therapy. Following glucocorticoid taper, she developed temporal headaches, jaw claudication, and scalp tenderness, raising concern for giant cell arteritis (GCA). Laboratory evaluation revealed markedly elevated inflammatory markers (erythrocyte sedimentation rate and C-reactive protein), microcytic anemia, mild hematuria, and strongly positive myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA) by antigen-specific immunoassay with negative proteinase-3 (PR3)-ANCA. Temporal artery biopsy demonstrated transmural inflammation affecting all vessel layers without giant cells or granulomata. The combination of multisystem small-vessel involvement, MPO-ANCA seropositivity with negative PR3-ANCA, and characteristic histopathological findings established the diagnosis of microscopic polyangiitis (MPA) with temporal arteritis rather than granulomatosis with polyangiitis (GPA) or GCA. Treatment with high-dose glucocorticoids (prednisone 80 mg daily), avacopan (30 mg twice daily), and rituximab (375 mg/m² weekly for four weeks) resulted in rapid improvement of constitutional and cranial symptoms. This case highlights the importance of integrating MPO-ANCA serology and histopathological findings when temporal arteritis is the presenting feature of systemic vasculitis. It illustrates the utility of avacopan-based, glucocorticoid-sparing combination immunosuppression in this context.
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Drug Discovery Landscape
1 orphan drug designation for Microscopic polyangiitis, including 1 approved therapy.
1 orphan drug designation for Microscopic polyangiitis, including 1 approved therapy.
Drug | Therapy type | Regulator | Orphan designation | Approval | Sponsor |
|---|---|---|---|---|---|
(2R,3S)-2-(4-cyclopentylaminophenyl)-1-(2-fluoro-6-methylbenzoyl)piperidine-3-carboxylic acid(4-methyl-3-trifluoromethylphenyl)amide | small molecules | EMA | 2014-11-19 | 2022-01-19 | Vifor Fresenius Medical Care Renal Pharma France |
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