Immunoadsorption and Plasma Exchange are Comparable in Anti-Neutrophil Cytoplasmic Antibodies or Anti-Glomerular Basement Membrane Removal Kinetics

Introduction

Apheresis allows the fast removal of autoantibodies in anti-glomerular basement membrane (anti-GBM) disease, and in severe antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis. The CINEVAS study tested whether immunoadsorption (IA) allowed a faster removal of ANCA and/or anti-GBM antibodies than plasma exchanges (PEx).

Methods

CINEVAS was a prospective multicenter study comparing IA to PEx in consecutive patients with ANCA and/or anti-GBM vasculitides. The primary objective was the reduction rate in autoantibody titers between the beginning of the first and the end of the seventh apheresis session. Secondary objectives were number of sessions needed to obtain desired reduction rates; reduction rates of total Ig levels; tolerance of sessions; and patients' outcome.

Results

The results of 38 patients (16 treated with IA and 22 with PEx), and 43 autoantibodies, were analyzed. There was no difference in the reduction rates in autoantibody titers between IA and PEx over 7 sessions (respectively 98% vs. 96%, P = 0.39). The numbers of sessions needed to obtain undetectable autoantibodies, or 50%, 75%, or 90% reductions, did not differ between techniques. Greater reduction rates of autoantibodies were observed when plasma was separated by filtration compared to centrifugation, with IA and PEx. IA allowed a greater reduction in total IgG levels, and better preservation of total IgA and IgM levels than PEx. PEx sessions required higher volumes of plasma, IA sessions higher volumes of citrate; IA sessions were longer.

Conclusions

IA and PEx were comparable in ANCA or anti-GBM removal kinetics, despite a faster reduction in total IgG with IA.

Genomic analysis of adult thrombotic microangiopathies in less than 3 days: From rapid to fast genomics to treatment

Using nanopore sequencing, we showed feasibility and impact of rapid genomic screening for managing thrombotic microangiopathies (TMAs) in 18 prospective cases, achieving diagnoses in less than three days. We compared results to standard exome sequencing, cost-efficiency and complement blockade initiation.

A randomized crossover trial of regional anticoagulation modalities for intermittent hemodialysis

INTRODUCTION

The optimal regional anticoagulation (RA) of dialysis filters in patients at risk of bleeding remains elusive. Inducing hypocalcemia within the filter by using a calcium-free dialysate has emerged as an easy-to-use heparin-free RA, including in critically ill patients, but comparative studies are lacking.

METHODS

We conducted a multicentre, randomized, crossover trial to compare the efficacy and tolerance of two RAs (heparin-coated membrane (HCM) or calcium free dialysate with calcium reinjection according to ionic dialysance (CFD)) in patients requiring hemodialysis and at risk of bleeding. During the study period, each patient received two dialysis sessions (one with each RA in a randomly assigned order). The primary endpoint was the proportion of dialysis sessions completed (≥ 240 min).

RESULTS

94 patients were included in the intention-to-treat analysis, including 16 critically ill patients (17.0%). Coagulation and inflammation parameters, as well as hemodynamic status at baseline, were balanced between groups. Premature coagulation of the filter occurred in 19 HCM (20.9%) compared to 3 (3.2%) CFD sessions. In half of the sessions with premature termination, coagulation occurred before 180 minutes. The proportion of patients who completed the CFD session while failing to complete the HCM session (n = 17) was significantly higher than the proportion of patients who completed the HCM session while failing to complete the CFD session (n = 1; p < 0.001). Hemodynamic and metabolic tolerance were not different between groups.

CONCLUSIONS

In individuals at risk of bleeding, RA with calcium-free dialysate significantly reduces the incidence of premature dialysis termination compared to heparin-coated membrane without safety concerns. Trial registration and statistical analysis plan: ClinicalTrials.gov identifier: NCT03842657.

Carfilzomib-associated thrombotic microangiopathy: clinical features and outcomes

BACKGROUND AND HYPOTHESIS

Carfilzomib, a new proteasome inhibitor indicated for patients with relapsed/refractory myeloma, has been associated with cases of thrombotic microangiopathy (CFZ-TMA). The role of variants in the complement alternative pathway and therapeutic potential of complement blockade with eculizumab remain to be determined.

METHODS

We report 37 cases of CFZ-TMA recorded in the French reference center for TMA with their clinical characteristics, genetic analysis and outcome according to treatments.

RESULTS

A trigger was identified in more than half of cases, including 8 influenza and 5 SARS-CoV-2 cases. All patients presented with acute kidney injury (AKI) (KDIGO stage 3 in 31 (84%) patients) while neurological (n=13, 36%) and cardiac damage (n=7, 19%) were less frequent. ADAMTS13 and complement activity were normal (n= 28 and 18 patients tested) and no pathogenic variant in the alternative complement pathway was found in 7 patients tested.TMA resolved in most (n=34, 94%) patients but 12 (44%) still displayed stage 3 AKI at discharge. Nineteen (51%) patients were treated with therapeutic plasma exchange, 14 (38%) patients received corticosteroids and 18 (50%) were treated with eculizumab. However none of these treatments demonstrated a significant impact on outcomes.

CONCLUSION

This study is the largest case series of CFZ-TMA since its approval in 2012. Patients present with severe AKI and experience frequent sequelae. Complement variants and blockade therapy do not seem to play a role in the pathophysiology and prognosis of the disease.

Diagnostic Yield of Exome Sequencing in Early-Onset Hypertensive Nephropathy in Adults

INTRODUCTION

Hypertensive nephrosclerosis (HN) ranks as one of the most frequent causes of chronic kidney disease (CKD), but its very existence has repeatedly been called into question, especially in young adults. Its diagnostic framework is established chiefly on non-specific clinical criteria, and its defining histopathological set of features is in fact shared by numerous other conditions. Genetic testing based on exome sequencing (ES) has emerged as a comprehensive tool to detect Mendelian diseases in timely fashion in nephrology, with a significant number of re-established diagnoses. The aim of this study was to investigate the diagnostic yield of ES in patients with a clinical diagnosis of hypertensive nephropathy.

METHOD

Since September 2018, ES has been readily available as part of the routine diagnostic work-up in our institution. The indication of ES includes hypertensive nephropathy of early onset (i.e., <45 years old). We retrospectively collected the ES data performed in the context of hypertensive nephropathy in our institution between September 2018 and February 2021.

RESULTS

A total of 128 patients were sequenced in the context of hypertensive nephropathy with early onset. The chief indications of ES were an early onset of CKD (47%), family history of kidney disease (8%), or both (18%). We detected diagnostic variants in 19 of the 128 patients (15%), encompassing a total of 13 different monogenic disorders. The diagnostic yield of ES was lower in patients of African ancestry (diagnostic yield of 7 vs. 30% in non-African ancestry patients, p < 0.001).

CONCLUSIONS

The high diagnostic yield of ES (15%) in a population of patients thought to have HN casts further doubts on the validity of the existing diagnosis criteria, including histological criteria, supposed to characterize the condition. This was especially true in patients with no African ancestry, where ES positivity reached 30%.

Legionnaires Disease in Solid Organ Transplant Recipients: A Decade-Long Nationwide Study in France

BACKGROUND

Legionnaires disease (LD) is a rare, life-threatening opportunistic bacterial infection that poses a significant risk to patients with impaired cell-mediated immunity such as solid organ transplant recipients. However, the epidemiologic features, clinical presentation, and outcomes of LD in this population are poorly described.

RESEARCH QUESTION

What are the clinical manifestations, radiologic presentation, risk factors for severity, treatment, and outcome of LD in solid organ transplant recipients?

STUDY DESIGN AND METHODS

In this 10-year multicenter retrospective cohort study in France, where LD notification is mandatory, patients were identified by hospital discharge databases. Diagnosis of LD relied on positive culture findings from any respiratory sample, positive urinary antigen test (UAT) results, positive specific serologic findings, or a combination thereof. Severe LD was defined as admission to the ICU.

RESULTS

One hundred one patients from 51 transplantation centers were eligible; 64 patients (63.4%) were kidney transplant recipients. Median time between transplantation and LD was 5.6 years (interquartile range, 1.5-12 years). UAT results were positive in 92% of patients (89/97). Among 31 patients with positive culture findings in respiratory samples, Legionella pneumophila serogroup 1 was identified in 90%. Chest CT imaging showed alveolar consolidation in 98% of patients (54 of 57), ground-glass opacity in 63% of patients (36 of 57), macronodules in 21% of patients (12 of 57), and cavitation in 8.8% of patients (5 of 57). Fifty-seven patients (56%) were hospitalized in the ICU. In multivariate analysis, severe LD was associated with negative UAT findings at presentation (P = .047), lymphopenia (P = .014), respiratory symptoms (P = .010), and pleural effusion (P = .039). The 30-day and 12-month mortality rates were 8% (8 of 101) and 20% (19 of 97), respectively. In multivariate analysis, diabetes mellitus was the only factor associated with 12-month mortality (hazard ratio, 3.2; 95% OR, 1.19-8.64; P = .022).

INTERPRETATION

LD is a late and severe complication occurring in solid organ transplant recipients that may present as pulmonary nodules on which diabetes impacts its long-term prognosis.

Magnesium sulphate in patients with thrombotic thrombocytopenic purpura (MAGMAT): a randomised, double-blind, superiority trial

PURPOSE

Studies have suggested benefits from magnesium sulphate in thrombotic thrombocytopenic purpura (TTP). We aimed to measure the effects of magnesium sulphate supplementation on TTP recovery.

METHODS

In this multicenter, randomised, double-blind, controlled, superiority study, we enrolled adults with a clinical diagnosis of TTP. Patients were randomly allocated to receive magnesium sulphate (6 g intravenously followed by a continuous infusion of 6 g/24 h for 3 days) or placebo, in addition to the standard treatment. The primary outcome was the median time to platelet normalisation (defined as a platelet count ≥ 150 G/L). Efficacy and safety were assessed by intention-to-treat.

RESULTS

Overall, we enrolled 74 participants, including one who withdrew his/her consent. Seventy-three patients were further analyzed, 35 (48%) allocated to magnesium sulphate and 38 (52%) to placebo. The median time to platelet normalisation was 4 days (95% confidence interval [CI], 3-4) in the magnesium sulphate group and 4 days (95% CI 3-5) in the placebo group. The cause-specific hazard ratio of response was 0.93 (95% CI 0.58-1.48, p = 0.75). The number of patients with ≥ 1 serious adverse reactions was similar in the two groups. By day 90, four patients in the magnesium sulphate group and two patients in the placebo group had died (p = 0.42). The most frequent adverse event was low blood pressure occurring in 34% in the magnesium sulphate group and 29% in the placebo group (p = 0.80).

CONCLUSION

Among patients with TTP, the addition of magnesium sulphate to the standard of care did not result in a significant improvement in time to platelet normalisation.

Immunoadsorption-Based HLA Desensitization in Patients Awaiting Deceased Donor Kidney Transplantation: An Interventional, Non-Randomised, Single Cohort Study

Whether immunoadsorption (IADS) as part of desensitization protocols could facilitate deceased donor kidney transplantation (KT) in highly sensitized (HS) patients remains to be proven. We retrospectively analyzed our IADS based desensitization protocol for deceased donor KTs between 2013 and 2018. Fifteen HS patients (age 52 years [40-56]) were included. Waiting time before IADS was 6 years [5-10] and the interval between IADS initiation and KT was 5 months [1-12] for the 14 transplanted patients. Nine patients had prior KT. Calculated panel reactive antibody decreased significantly during the protocol (99.3% [92.5-99.9] vs. 79.4% [56.7-81.9]; p = 0.004). Death-censored graft survival was 85.7% at 1 and 2 years post-transplantation. One-year median plasma creatinine level was 135 µmol/L [111-202]. Six developed active antibody mediated rejection (ABMR) at 1 year, with a median delay of 13 days [11-26]. Eight patients developed severe infections, including two fatal outcomes. Finally, compared to 93% of patients who received desensitization receiving a KT, only 43% of a control with similar characteristics underwent transplantation. However, no difference was found in overall probability of being alive with a functioning graft at the end of follow-up. The results indicate that our IADS-based desensitization strategy was not effective due to a high rate of ABMR and severe infectious complications which pose a challenge to its universalization.

Hepatitis B Virus Reactivation in Kidney Transplant Recipients Treated With Belatacept

Introduction

Hepatitis B virus (HBV) reactivation in kidney transplant recipients has been reported in 3% to 9% of anti-HBc antibody (HBcAb)-positive HBs antigen (HBsAg)-negative patients. It has not been studied in patients receiving belatacept, a selective costimulation blocker.

Methods

We performed a retrospective study of all transplant recipients receiving belatacept in 2 kidney transplantation centers in France. Among HBcAb-positive patients, we analyzed HBV reactivation rate, outcomes, and risk factors.

Results

A total of 135 patients treated with belatacept were included: 32 were HBcAb-positive and 2 were HBsAg-positive. Seven patients reactivated HBV (21.9% of HBcAb-positive patients), including 5 HBsAg-negative patients (16.7% of HBcAb-positive HBsAg-negative patients). Reactivation occurred 54.8 (± 70.9) months after transplantation. One patient presented with severe hepatitis and 1 patient developed cirrhosis. There was no significant difference in survival between patients that reactivated HBV and patients that did not: 5-year patient survival of 100% (28.6; 100) and 83.4% (67.6; 100), respectively (P = 0.363); and 5-year graft survival of 100% (28.6; 100) and 79.8% (61.7; 100), respectively (P = 0.335). No factor, including HBsAb positivity and antiviral prophylaxis, was statistically associated with the risk of HBV reactivation.

Conclusion

HBV reactivation rate was high in patients treated with belatacept when compared with previous transplantation studies. HBV reactivation did not impact survival. Further studies are needed to confirm these results. A systematic antiviral prophylaxis for these patients should be considered and evaluated.

Exome-First Strategy in Adult Patients With CKD: A Cohort Study

Introduction

Exome sequencing (ES) has widened the field of nephrogenomics in adult nephrology. In addition to reporting the diagnostic yield of ES in an adult cohort study, we investigated the clinical implications of molecular diagnosis and developed a clinical score to predict the probability of obtaining positive result.

Methods

From September 2018 we have used ES to prospectively perform a first-tier liberal exploration of adult nephropathies of unknown origin and/or when a genetic kidney disease was clinically suggested. We also analyzed copy number variant using the same assay.

Results

Molecular diagnosis was made in 127 of 538 patients sequenced (diagnostic yield: 24%), comprising 47 distinct monogenic disorders. Eight of these monogenic disorders (17% [8/47]) accounted for 52% of genetic diagnoses. In 98% (n = 125/127) of the patients, the genetic information was reported to have major clinical implications. We developed a 4-value clinical score to predict the probability of obtaining a molecular diagnosis (area under the receiver operating characteristics curve [AUC] 0.726 [95% confidence interval: 0.670-0.782]) (available at http://allogenomics.com/score).

Conclusion

This study reinforces the role of ES as a first-tier exploration for adult chronic kidney disease patients in whom phenotypes are often poor and atypical. Although external validation is required, our clinical score could be a useful tool for the implementation of nephrogenomics in adults.

Stratégies innovantes de vaccination anti-pneumococcique par rapport au schéma standard chez les patients atteints de vascularites associées aux ANCA recevant du rituximab : essai contrôlé randomisé multicentrique (PNEUMOVAS)

Introduction

Les patients recevant des glucocorticoïdes et du rituximab (RTX) présentent un risque accru d’infections, en particulier d’infections invasives à pneumocoque. Les réponses vaccinales au virus de la grippe, au Streptococcus pneumoniae et au SARS-CoV-2 sous traitement par RTX sont fortement altérées. Chez les patients atteints de maladies auto-immunes recevant de tels traitements, en particulier ceux atteints de vascularites associées aux ANCA (AAV), il est donc nécessaire de développer des stratégies vaccinales anti-pneumococciques améliorées pour augmenter la réponse immunitaire et la protection vaccinale.

Patients et méthodes

Cet essai multicentrique de phase 2, randomisé, ouvert, a comparé deux stratégies innovantes de vaccin anti-pneumococcique « renforcées » au schéma de vaccination standard chez des patients atteints de VAA recevant un traitement par RTX. Des patients adultes atteints de VAA nouvellement diagnostiquée ou en rechute, présentant une maladie active (BVAS ≥ 3) et devant recevoir du RTX comme traitement d’induction (375 mg/m²/semaine pendant 4 semaines consécutives), ont été randomisés avec un rapport 1:1:1 dans trois bras parallèles : schéma standard associant une dose de vaccin pneumococcique conjugué 13-valent (PCV13) au jour 0 suivie d’une dose de vaccin non conjugué 23-valent (PPV23) au mois 5 (M5) (bras 1) ; double dose de PCV13 au jour 0 et au jour 7 suivie d’une dose de PPV23 à M5 (bras 2) ; ou 4 doses de PCV13 au jour 0 suivies d’une dose de PPV23 à M5 (bras 3). Le critère d’évaluation principal était la réponse immunitaire à M6 contre les 12 sérotypes de pneumocoque communs aux vaccins PCV13 et PPV23, classée selon quatre catégories ordonnées de réponse : réponse positive en anticorps contre 0–3, 4–6, 7–9 ou 10–12 sérotypes. Une réponse positive par sérotype était définie par un titre ELISA d’IgG spécifiques ≥ 1 μg/mL et une augmentation de deux fois par rapport au jour 0. Le critère d’évaluation primaire a été analysé dans un modèle de régression logistique à chances proportionnelles avec une correction de Bonferonni pour les 2 bras innovants. Les critères d’évaluation secondaires étaient les réactions locales et systémiques sollicitées 7 jours après chaque vaccination et tout événement indésirable lié ou pouvant être lié à l’immunisation vaccinale.

Résultats

Quatre-vingt-quinze participants ont été analysés dans la population modifiée en intention de traiter (âge moyen 60 ± 16,6 ans, 50 % d’hommes, 74 personnes atteintes d’une maladie nouvellement diagnostiquée, 66 d’une granulomatose avec polyangéite et 29 d’une polyangéite microscopique, BVAS moyen 15,3 ± 6,9), dont 30 affectés au bras 1, 32 au bras 2 et 33 au bras 3.

À M6, une réponse immunitaire contre 0–3, 4–6, 7–9 ou 10–12 sérotypes était observée chez 83,3 %, 13,3 %, 3,3 % et 0 % dans le bras 1 ; 56,3 %, 28,1 %, 15,6 % et 0 % dans le bras 2 ; et 60,6 %, 33,3 %, 6,1 % et 0 % dans le bras 3. Les patients du bras 2 étaient significativement plus susceptibles de se trouver dans une catégorie de réponse supérieures par rapport au régime standard après ajustement sur l’âge, avec un odds ratio proportionnel (pOR) de 4,1 (IC97,5 % : 1,1–15,9, p = 0,018), tandis que le bras 3 montrait une tendance non significative à améliorer les réponses vaccinales (pOR : 3,1, IC97,5 % : 0,8–11,9, p = 0,062). Une analyse de sensibilité sur une population per-protocole excluant les patients ayant subi des vaccinations ou des prises de sang hors des délais donnait des estimations concordantes.

Les réactions locales et/ou systémiques dans les 7 jours après chaque vaccination, et tout événement indésirable lié ou possiblement lié à la vaccination au cours des 6 premiers mois, sont survenus en plus grand nombre avec les schémas renforcés mais étaient principalement des réactions locales de grade 1 ou 2. Aucun événement indésirable grave lié à la vaccination n’a été observé.

Au cours du suivi, 8 poussées de vascularite sont survenues chez 6 patients, en médiane 87 jours après la dernière vaccination : un patient dans le bras 1, 2 dans le bras 2, et 3 dans le bras 3.

Conclusion

Chez les patients atteints de VAA recevant un traitement par RTX, une stratégie innovante de vaccination anti-pneumococcique renforcée, basée sur une double dose de PCV13 au jour 0 et au jour 7 suivie d’une dose unique de PPV23 à M5, améliore significativement les réponses en anticorps contre Streptococcus pneumoniae par rapport au schéma standard.

MO367: Non-Invasive Diagnosis of Vancomycin-Induced Acute Kidney Injury Using Urine Microscopy

BACKGROUND AND AIMS

Vancomycin stands out both as being a potent cause of AKI (V-AKI) and as one of the most universally prescribed antimicrobial drugs. From a pathophysiological standpoint, it was hitherto believed that V-AKI stemmed from the intracellular accumulation of vancomycin in the proximal tubule, which elicits oxidative stress and ultimately translates in cell apoptosis. Recently, a study has shown that vancomycin in the setting of overt drug overdose, can co-precipitate with uromodulin causing microspheric obstructive aggregates in the tubular lumen both in experimental models and in patients [1]. Further documentation of this novel mechanism has been hindered by the need to procure kidney tissue so as to perform ad hoc immunostaining. Furthermore, it remains to be proven that the presence of vancomycin microspheres represents a reliable marker for V-AKI. Urine based vancomycin-immunostaining may represent a valuable non-invasive approach.

METHOD

The urine of patients presenting with vancomycin overdose determined by plasma trough levels &gt;15 mg/L along with acute kidney injury (according to KDIGO guidelines) were subjected to light microscopic urinalysis. Whenever microscopic urinalysis yielded the presence of casts, immunostaining was performed. Briefly, a pellet of urine was spread on a slide and immunostaining performed with a specific anti-vancomycin antibody (Abbot 6E-4421, 1/1000) prior to repeat microscopic examination. Infrared spectrophotometry was performed to ascertain the nature of the casts by comparing the spectrum to a reference vancomycin spectrum.

Patients were deemed to have V-AKI whenever at least one vancomycin positive cast was observed following immunostaining.

The urine of control patients was subjected to the same procedure: they were defined as patients exposed to vancomycin with or without vancomycin overdose but with no AKI.

RESULTS

A total of 5 patients with vancomycin overdose KDIGO stage 3 AKI were found to exhibit casts with positive vancomycin immunostaining (Fig. 1). On light microscopic urinalysis, vitreous casts devoid of refringence after polarization could be observed in each case. Upon infrared spectrophotometry, the casts displayed a Fourier transform spectrum consistent with vancomycin.

In three of the cases, V-AKI was considered the sole or primary cause of AKI. The patient displayed abundant and markedly stained casts upon anti-vancomycin immunostaining (Fig. 1A). Overt and massive vancomycin overdosing was evidenced in all cases. In one case, the patient concurrently received piperacillin-tazobactam and in another case the patient was exposed to iodinated contrast media. The renal function course was favourable with full recovery in all three instances.

In two cases, competing causes of AKI were either evidenced or not. In one case, the patient displayed septic shock which indicated vancomycin therapy. In another case, the patient was suspected to have immunoallergic intersititial nephritis. The patients exhibited rare casts with only faint staining (Fig. 1B). In both cases, vancomycin overdose could not be documented. V-AKI was deemed a possible concurrent cause of AKI.

None of the 5 control patients yielded casts after light microscopic urinalysis.

CONCLUSION

Vancomycin cast detection on urine microscopy is feasible and can be enhanced by a straightforward immunostaining technique and represents a unique opportunity for a non-invasive diagnosis of V-AKI. Further studies are required to refine diagnostic criteria-based urine immunostaining detection. They also needed to determine whether detection of V-AKI merely reflects impaired vancomycin urinary excretion in the setting of AKI or can be regarded as a sensitive and specific marker of vancomycin-induced tubular obstruction and injury.

FC030: Diagnostic Yield of Exome Sequencing in Hypertensive Nephropathy

BACKGROUND AND AIMS

Hypertensive nephrosclerosis ranks as one of the most frequent causes of chronic kidney disease (CKD) worldwide and is deemed to be especially prevalent among patients of African ancestry [1]. The very existence of hypertensive nephropathy has been called into question, especially in young adults. Its diagnostic framework is based on non-specific clinical criteria, and its histopathological features are in fact unspecific.

Genetic testing with exome sequencing (ES) has emerged as a comprehensive tool to detect Mendelian diseases in nephrology with a significant number of post-hoc re-established diagnoses [2]. Nevertheless, ES has yet to be incorporated into the diagnostic workup of patients with hypertensive nephropathy consistently.

This study aimed to investigate the diagnostic yield of ES in patients with a clinical diagnosis of hypertensive nephropathy.

METHOD

Since September 2018, ES is readily available as part of the routine diagnostic workup in our institution. The indication of ES includes hypertensive nephropathy of early onset (i.e. &lt;45 years old). We retrospectively collected the ES performed in the context of hypertensive nephropathy [3] in our institution between September 2018 and February 2021.

RESULTS

A total of 128 patients were sequenced in the context of hypertensive nephropathy with early-onset. Women were 29 (22.7%), the mean age was 43 (35; 51) years and 60% of them were patients of African ancestry. The main indications of ES was an early onset of CKD (47%), a family history of kidney disease (8%) or both (18%). We detected diagnostic variants (ACM class 4/5) in 22 of the 128 patients (17.2%) encompassing a total of 16 different monogenic disorders. Two diseases accounted for more than half of the genetic diagnoses: nephronophthisis (n = 7, 32%) and Alport syndrome (n = 5, 23%). Complement variation did not account for a significant part of the diagnosis.

The diagnostic yield of ES was lower in patients of African ancestry (diagnostic yield of 10.4% versus 27.4% in the non-African ancestry patients; P = 0.01). Co-segregation data was lacking in patients of African ancestry, with significantly more ES performed in singleton (96% compared with 76% in non-African ancestry patients; P &lt; 0.001).

In addition to disease reclassification, genetic diagnosis enabled guidance for family counseling (n = 11, 50% of positive patients) and thus helped for potential related donor selection for transplantation. In the whole cohort, ES results modified the therapeutic in 6 patients (5%) and ruled out potential recurrence in the graft in 10 patients (8%).

CONCLUSION

Physicians should be wary of tentative diagnosis of nephrosclerosis, especially in patients of non-African ethnic background. Instead, it should prompt genetic investigations, which overturned the initial diagnosis in 17% of the cases. The lower diagnostic yield of ES in patients of African ancestry in our cohort might partly be due to the lack of available co-segregation data, as well as the underrepresentation of subjects of African ancestry in the reference genome.

MO043: Role of the I416L variant of complement factor I in the occurrence of thrombotic microangiopathy among patients of African ancestry

BACKGROUND AND AIMS

Complement dependent hemolytic and uremic syndrome (c-HUS) predisposes to hypertensive crisis and chronic hypertension. Reciprocally, hypertensive crisis may precipitate thrombotic microangiopathy (TMA) via endothelial shear stress. Patients of African ancestry have long been recognized for their predisposition to both chronic hypertension and chronic kidney disease (CKD). Yet, despite growing evidence meant to bridge the divide between the complement alternative pathway and hypertensive crisis [1] (i) c-HUS is only known to account for a small fraction of the cases of malignant HTA (5%) [2] or TMA (4%) [3] (ii) complement genetic investigations in the population of African ancestry are sparse. Recently, the I416L CFI variant, which is specific to patients of African ancestry, has been classified as likely pathogenic (https://databases.lovd.nl/shared/variants/0000521158#00005040). By running a query through the BIOMNIS genetic databank, we sought to identify and provide a phenotypic description of the patients carrying the I416L CFI variant.

METHOD

All samples were sequenced at the BIOMNIS center (Lyon, France) using the Illumina platform and subsequently processed via the in-center bioinformatics pipeline. The BIOMNIS genetic databank compiles a total of 2886 whole exome sequencing (WES) nationwide (single unrelated patients) for renal (n = 1200) and non-renal indications (n = 1686). Once patients were recognized to carry the I416 variant, deidentified clinical data was provided by the attending nephrologist.

RESULTS

Among 1686 WES performed for non-renal indications, three unrelated patients harbored the I416L variant. Out of the 1200 WES performed for renal indications, we identified eight unrelated patients carrying the I416L CFI variant. All patients were of African Ancestry and were heterozygous for the variant, including five males with median age of 38.5 years. They all shared a common history remarkable for hypertension of early onset at median of 33 years [21–38]. None of these patients were acknowledged to have c-HUS prior to WES. In six cases, the kidney disease was undetermined. Four patients experienced TMA: three during bouts of malignant hypertension with concurrent biological TMA. One of them exhibited signs of TMA on biopsy with superimposed signs of malignant nephrosclerosis and another on a kidney transplant. Three patients disclosed genetic risk factor for kidney disease including Apol1 pathogenic variants (G1 and/or G2) (n = 2) and URAT1-related pathogenic variant (n = 1). Five patients had at least one additional risk factor for renal disease. All but one patient progressed to CKD including end-stage CKD on four instances with a median follow-up of 6.5 years. One patient presented with TMA following kidney transplantation. Only one patient whose hypertensive crisis manifested as preeclampsia and HELLP was free of CKD on last follow-up.

CONCLUSION

C-HUS may go unrecognized or mimic vascular nephropathy. These results make a case for a streamlined genotyping of patients, especially patients of African ancestry with a history of hypertension of early onset. Additional triggers acting as second ‘hits’ such as hypertension, pregnancy or genetic and non-genetic renal risk factors may aggravate the course of kidney disease. Yet, further investigations are warranted to appreciate the true clinical significance of this variant as it entails momentous therapeutic and medico-economic implications, most notably the use of anti-C5 therapy.

Endopeptidase Cleavage of Anti-Glomerular Basement Membrane Antibodies in vivo in Severe Kidney Disease: An Open-Label Phase 2a Study

BACKGROUND

The prognosis for kidney survival is poor in patients presenting with circulating anti-glomerular basement membrane (GBM) antibodies and severe kidney injury. It is unknown if treatment with an endopeptidase that cleaves circulating and kidney bound IgG can alter the prognosis.

METHODS

An investigator-driven phase 2a one-arm study (EudraCT 2016-004082-39) was performed in 17 hospitals in five European countries. A single dose of 0.25 mg/kg of imlifidase was given to 15 adults with circulating anti-GBM antibodies and an eGFR <15 ml/min per 1.73m². All patients received standard treatment with cyclophosphamide and corticosteroids, but plasma exchange only if autoantibodies rebounded. The primary outcomes were safety and dialysis independency at 6 months.

RESULTS

At inclusion, ten patients were dialysis dependent and the other five had eGFR levels between 7 and 14 ml/min per 1.73m². The median age was 61 years (range 19-77), six were women, and six were also positive for anti-neutrophil cytoplasmic antibodies. Then 6 hours after imlifidase infusion, all patients had anti-GBM antibodies levels below the reference range of a prespecified assay. At 6 months 67% (ten out of 15) were dialysis independent. This is significantly higher compared with 18% (nine out of 50) in a historical control cohort (P<0.001, Fisher's exact test). Eight serious adverse events (including one death) were reported, none assessed as probably or possibly related to the study drug.

CONCLUSIONS

In this pilot study, the use of imlifidase was associated with a better outcome compared with earlier publications, without major safety issues, but the findings need to be confirmed in a randomized controlled trial.Clinical Trial registration number: EUDRACT 2016-004082-39 https://www.clinicaltrialsregister.eu/ctr-search/trial/2007-001377-28/results.

Kidney Histopathology Can Predict Kidney Function in ANCA-Associated Vasculitides with Acute Kidney Injury Treated with Plasma Exchanges

BACKGROUND

Data from the PEXIVAS trial challenged the role of plasma exchange (PLEX) in ANCA-associated vasculitides (AAV). We aimed to describe kidney biopsy from patients with AAV treated with PLEX, evaluate whether histopathologic findings could predict kidney function, and identify which patients would most benefit from PLEX.

METHODS

We performed a multicenter, retrospective study on 188 patients with AAV and AKI treated with PLEX and 237 not treated with PLEX. The primary outcome was mortality or KRT at 12 months (M12).

RESULTS

No significant benefit of PLEX for the primary outcome was found. To identify patients benefitting from PLEX, we developed a model predicting the average treatment effect of PLEX for an individual depending on covariables. Using the prediction model, 223 patients had a better predicted outcome with PLEX than without PLEX, and 177 of them had >5% increased predicted probability with PLEX compared with without PLEX of being alive and free from KRT at M12, which defined the PLEX-recommended group. Risk difference for death or KRT at M12 was significantly lower with PLEX in the PLEX-recommended group (-15.9%; 95% CI, -29.4 to -2.5) compared with the PLEX not recommended group (-4.8%; 95% CI, 14.9 to 5.3). Microscopic polyangiitis, MPO-ANCA, higher serum creatinine, crescentic and sclerotic classes, and higher Brix score were more frequent in the PLEX-recommended group. An easy to use score identified patients who would benefit from PLEX. The average treatment effect of PLEX for those with recommended treatment corresponded to an absolute risk reduction for death or KRT at M12 of 24.6%.

CONCLUSIONS

PLEX was not associated with a better primary outcome in the whole study population, but we identified a subset of patients who could benefit from PLEX. However, these findings must be validated before utilized in clinical decision making.