AB0616 Myeloperoxidase (MPO) positive extracellular vesicles (EVs) expressing complement split products in Anti - Neutrophil Cytoplasmic Antibody (ANCA) -associated Vasculitis (AAV)

Background

Complement activation has a critical role for the development of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). We have previously shown increased expression of complement split products C3a and C5a on myeloperoxidase (MPO) positive EVs (MPO+EVs) in plasma from AAV patients with kidney involvement compared to the patients with non-renal disease and the EV-levels correlated with disease activity (1).

Objectives

To investigate the expression of a larger set of complement components on circulating MPO+EVs in relation to disease activity and kidney involvement in patients with AAV.

Methods

Eighty-nine patients with AAV and 23 healthy controls were included. The concentration of MPO+EVs expressing complement split products C3a, C4d, C5a, terminal complement complex-TCC (C5b-9) or complement factor B (CFB) were analyzed from citrate plasma by flow cytometry. The assessment of vasculitis disease activity was performed using the Birmingham Vasculitis Activity Score (BVAS).

Results

In the AAV group, there were 47 males (52.8%), the median age was 56 years and 33 (37.1%) patients were anti-MPO-positive and 54 (60.7%) were anti-PR3-positive. Two patients were positive for both antibodies. Median disease duration for patients with active AAV (BVAS>0; n=81) was 4 days and for patients in remission (BVAS 0; n=8) 1259 days. 64% had kidney involvement (n=52). Highly active AAV (BVAS ≥12) was noted in 62 patients, of whom 49 patients had kidney involvement. Active disease (0<BVAS<12) was seen in 19 patients. AAV patients had significantly higher levels of MPO+, MPO+C3a+, MPO+C4d+ and MPO+TCC+ EVs compared to healthy controls (all p<0.001). Patients in remission had higher levels of MPO+, MPO+C4d+ and MPO+TCC+ EVs compared to healthy controls (all p≤0.001). There was a significant difference in levels of MPO+(p=0.02), MPO+C3a+(p<0.001), MPO+C4d+(p<0.001) and MPO+TCC+ EVs (p<0.001) in patients with kidney involvement compared with patients without (n=29) (Figure 1). For patients with BVAS>0 there was a weak correlation between MPO+, MPO+C3a+, MPO+C4d+, MPO+TCC+ EVs and BVAS. Kidney biopsies from 34 patients were classified according to histopathological class (2): crescentic (n=6), focal (n=18), mixed (n=6), sclerotic (n=4). The level of MPO+C4d+EVs was higher in the sclerotic type compared to focal (p=0.04, 95% CI [2.4–103.7]) and mixed (p=0.04, 95% CI [1.4–119.1]).

Conclusion

Levels of EVs expressing complement split products were generally increased in AAV patients and patients with kidney involvement had higher levels of total MPO+EVs exposing C3a, C4d or TCC compared with patients without suggesting a role in kidney AAV pathogenesis. Patients with sclerotic kidney histotype had higher levels of MPO+C4d EVs compared with focal and mixed subgroups pointing to that activation of the classical complement pathway may be of importance in severe forms of kidney AAV.

References

[1]Antovic A et al. J Rheumatol. 2020 May 1;47(5):714-721. doi: 10.3899/jrheum.181347. Epub 2019 Aug 1. PMID: 31371653.

[2]Berden AE et al. J Am Soc Nephrol. 2010 Oct;21(10):1628-36. doi: 10.1681/ASN.2010050477. Epub 2010 Jul 8. PMID: 20616173.

Disclosure of Interests

None declared

MO245OUTCOME OF DIFFERENT INDUCTION REGIMENS IN ANCA-ASSOCIATED GLOMERULONEPHRITIS ACCORDING TO THE HISTOPATHOLOGICAL CHARACTERISTICS: THE REASSESS STUDY*

Background and Aims

Renal involvement in ANCA-associated vasculitis (AAV) impacts significantly on patients’ prognosis. The role of different induction regimens on remission rates and long-term renal outcomes according to renal histological characteristics has not been explored yet.

Method

AAV patients with biopsy-proven renal involvement were collected retrospectively from eleven centers and stratified according to the induction regimen employed: Rituximab (RTX), Cyclophosphamide (CYC) or both (RTX-CYC). Kidney biopsies were classified according to the Berden and Brix classifications.

Renal remission rate was assessed 6 months after the induction regimen and defined as a renal Birmingham Vasculitis Activity Score (BVAS) of 0.

Among patients who achieved remission at 6 months, renal relapse was defined as a renal-BVAS&gt;0 associated with an increase in immunosuppressive treatment.

ESRD was defined as an eGFR&lt;15 ml/min/1,73m2, need for dialysis or renal transplant.

Results

323 patients were identified and followed-up for a median time of 36 months (IQR 18-72). The cohort included 38% patients with GPA and 62% with MPA, 53% patients were MPO-ANCA and 41% PR3-ANCA positive. The median baseline eGFR in the overall cohort was 19 ml/min/1,73m2 (IQR 12- 34). 58% of patients were treated with CYC, 24% with RTX-CYC and 18% with RTX.

According to the Berden classification, 24% biopsies were classified as Focal, 31% as Crescentic, 33% as Mixed and 12% as Sclerotic. The Brix score was assessable in 270/323 (84%) patients: 17%, 52% and 31% were respectively in the Low, Medium and High-risk class.

The overall renal remission at 6 months was 90%; according to the Berden classification, 94% patients achieved remission in the Focal, 88% in the Crescentic, 91% in the Mixed and 86% in the Sclerotic class. According to the Brix risk score, 88% patients achieved remission in the High risk, 91% in the Medium and 96% in the Low-risk class. According to induction regimen employed, 91%, 90% and 90% patients achieved remission in the RTX, CYC and RTX plus CYC group respectively.

In a logistic regression model adjusted for sex, age, ANCA type, AAV diagnosis, creatinine and proteinuria at onset, the induction regimen employed was not predictive of renal remission at 6 months, neither in Berden Focal plus Crescentic and Mixed plus Sclerotic classes, nor in Brix High and Low plus Medium risk classes.

Of the 185 patients with at least 6 months of follow-up available after remission, 25% experienced a renal relapse. In a Cox regression model adjusted for sex, age, ANCA type, AAV diagnosis, creatinine and proteinuria at onset, the induction regimen or histological score were not predictive of renal relapse. In the unadjusted survival analysis with the Kaplan-Maier curve, patients in the Crescentic group treated with RTX had a shorter ESRD-free survival compared to the CYC group (p=0.033) and the RTX-CYC group (p=0.044); figure 1:

This was confirmed also with a Cox regression analysis adjusted for sex, age, ANCA type, AAV diagnosis, creatinine and proteinuria when comparing the RTX group with the CYC one (HR 8.30 [95% CI 1.64 to 42.01], p=0.011); figure 2:

While the eGFR changes over time in the Focal plus Crescentic and Mixed plus Sclerotic classes showed a similar trend between treatment groups, in the Crescentic class the median eGFR values in the RTX group tended to be lower compared to the CYC and the RTX-CYC ones; figure 3:

The rate of severe infections in the RTX, CYC and RTX-CYC group was respectively 6.3, 8.5 and 8.8 per 100 patient-years during the first 12 months.

Conclusion

in a retrospective multicenter survey, response rates and relapse risk after different induction regimens in AAV patients with renal involvement were comparable in the overall cohort and in the different histopathological subgroups.

Although in a small subset of patients, the ESRD-free survival in the Crescentic class was shorter in the RTX group compared to the CYC one.

Natalizumab, rituximab and fingolimod as escalation therapy in multiple sclerosis

BACKGROUND AND PURPOSE

Breakthrough disease on first-line injectables in relapsing-remitting multiple sclerosis (RRMS) is a common clinical situation where comparative studies between different escalation therapies are lacking. The aim of this study was to compare the efficacy, safety and medication persistence of natalizumab (NTZ), rituximab (RTX) and fingolimod (FGL) as escalation therapy in RRMS.

METHODS

Patients switching from interferon or glatiramer acetate to NTZ, RTX or FGL due to breakthrough disease were identified through the Swedish multiple sclerosis (MS) registry at four large MS centers in this retrospective observational study. Data were collected from the MS registry and medical charts. Hazard ratios (HRs) for relapses, adverse events and drug discontinuation with 95% confidence interval (CI) were calculated using multivariable confounder-adjusted Cox proportional hazard models.

RESULTS

A total of 241 patients were included. The annualized relapse rates were 0.02 for NTZ, 0.03 for RTX and 0.07 for FGL. Compared with NTZ, the adjusted HR for relapse was 1.0 (95% CI, 0.2-5.6) for RTX and 3.4 (95% CI, 1.3-9.2) for FGL. The annualized drug discontinuation rates were 0.15, 0.01 and 0.15 for NTZ, RTX and FGL, respectively. The adjusted HR for drug discontinuation was 0.05 (95% CI, 0.01-0.38) for RTX and 1.0 (95% CI, 0.6-1.7) for FGL vs. NTZ.

CONCLUSIONS

In patients with RRMS on interferon/glatiramer acetate with breakthrough disease, switching to NTZ or RTX was associated with less disease activity compared with FGL. RTX displayed superior medication persistence compared with both NTZ and FGL.