Hypoxia-inducible factor prolyl hydroxylase inhibitors for anaemia in chronic kidney disease: a document by the European Renal Best Practice board of the European Renal Association.

Anaemia is a common complication of chronic kidney disease (CKD) and is associated with poor long-term outcomes and quality of life. The use of supplemental iron, erythropoiesis stimulating agents (ESAs) and blood transfusions has been the mainstay of treatment of anaemia in CKD for more than three decades. Despite available treatments, CKD patients with anaemia are undertreated and moderate-to-severe anaemia remains prevalent in the CKD population. Anaemia has consistently been associated with greater mortality, hospitalisation, cardiovascular events, and CKD progression in patients with CKD, and the risk increases with anaemia severity. Hypoxia-inducible factor (HIF) prolyl hydroxylase (PH) inhibitors have a novel mechanism of action by mimicking the body's response to hypoxia and have emerged as an alternative to ESAs for the treatment of anaemia in CKD. Their efficacy in correcting and maintaining haemoglobin has been demonstrated in over 30 phase 3 clinical trials. Additionally, HIF activation results in various pleiotropic effects beyond erythropoiesis with cholesterol reduction and improved iron homeostasis and potential anti-inflammatory effects. The long-term safety of these agents, particularly with respect to cardiovascular and thromboembolic events, and their possible effect on tumor growth requires to be fully elucidated. This document presents in detail the effects of HIF-PH inhibitors, describes their mechanisms of action and pharmacologic properties, and discusses their place in the treatment of anaemia in CKD according to the available evidence.

Effects of rare kidney diseases on kidney failure: a longitudinal analysis of the UK National Registry of Rare Kidney Diseases (RaDaR) cohort.

BACKGROUND: Individuals with rare kidney diseases account for 5-10% of people with chronic kidney disease, but constitute more than 25% of patients receiving kidney replacement therapy. The National Registry of Rare Kidney Diseases (RaDaR) gathers longitudinal data from patients with these conditions, which we used to study disease progression and outcomes of death and kidney failure. METHODS: People aged 0-96 years living with 28 types of rare kidney diseases were recruited from 108 UK renal care facilities. The primary outcomes were cumulative incidence of mortality and kidney failure in individuals with rare kidney diseases, which were calculated and compared with that of unselected patients with chronic kidney disease. Cumulative incidence and Kaplan-Meier survival estimates were calculated for the following outcomes: median age at kidney failure; median age at death; time from start of dialysis to death; and time from diagnosis to estimated glomerular filtration rate (eGFR) thresholds, allowing calculation of time from last eGFR of 75 mL/min per 1·73 m2 or more to first eGFR of less than 30 mL/min per 1·73 m2 (the therapeutic trial window). FINDINGS: Between Jan 18, 2010, and July 25, 2022, 27 285 participants were recruited to RaDaR. Median follow-up time from diagnosis was 9·6 years (IQR 5·9-16·7). RaDaR participants had significantly higher 5-year cumulative incidence of kidney failure than 2·81 million UK patients with all-cause chronic kidney disease (28% vs 1%; p<0·0001), but better survival rates (standardised mortality ratio 0·42 [95% CI 0·32-0·52]; p<0·0001). Median age at kidney failure, median age at death, time from start of dialysis to death, time from diagnosis to eGFR thresholds, and therapeutic trial window all varied substantially between rare diseases. INTERPRETATION: Patients with rare kidney diseases differ from the general population of individuals with chronic kidney disease: they have higher 5-year rates of kidney failure but higher survival than other patients with chronic kidney disease stages 3-5, and so are over-represented in the cohort of patients requiring kidney replacement therapy. Addressing unmet therapeutic need for patients with rare kidney diseases could have a large beneficial effect on long-term kidney replacement therapy demand. FUNDING: RaDaR is funded by the Medical Research Council, Kidney Research UK, Kidney Care UK, and the Polycystic Kidney Disease Charity.

A phase 2b, randomized, double-blind, placebo-controlled, clinical trial of atacicept for treatment of IgA nephropathy.

Atacicept is a first-in-class, dual anti-B-cell Activation Factor-A Proliferation-Inducing Ligand fusion protein in clinical evaluation for treatment of IgA nephropathy. To compare efficacy and safety of atacicept versus placebo in patients with IgAN, this randomized, double-blind, placebo-controlled phase 2b clinical trial ORIGIN enrolled 116 individuals with biopsy-proven IgA nephropathy. Participants were randomized to atacicept 150, 75, or 25 mg versus placebo once weekly for up to 36 weeks. Primary and key secondary endpoints were changes in urine protein creatinine ratio based on 24-hour urine collection at weeks 24 and 36, respectively, in the combined atacicept 150 mg and 75 mg group versus placebo. The primary endpoint was met at week 24 as the mean urine protein creatinine ratio was reduced from baseline by 31% in the combined atacicept group versus 8% with placebo, resulting in a significant 25% reduction with atacicept versus placebo. At week 36, the key secondary endpoint was met as the mean urine protein creatinine ratio reduced from baseline by 34% in the combined atacicept group versus a 2% increase with placebo, resulting in a significant 35% reduction with atacicept versus placebo. The reduction in proteinuria was accompanied by stabilization in endpoint eGFR with atacicept compared to a decline with placebo at week 36, resulting in significant between-group geometric mean difference of 11%, approximating an absolute difference of 5.7 mL/min/1.73m2. Endpoint galactose deficient IgA1 levels significantly decreased from baseline by 60% versus placebo. The safety profile of atacicept was like placebo. Thus, our results provide evidence to support a pivotal, phase 3 study of atacicept in IgA nephropathy.

Charting new frontiers in IgA nephropathy: a paradigm shift toward precision medicine and early intervention?

Advancements in glomerular transcriptomics offer a promising avenue toward precision medicine in IgA nephropathy. Traditional prognostic biomarkers, including proteinuria, blood pressure, and histomorphometry, fall short at capturing the complexity of IgA nephropathy and can only crudely guide therapeutic decisions. This issue needs to be addressed urgently as pathway-specific treatments become available. Glomerular transcriptomics, although technically challenging, offers an opportunity to refine prognostic precision and identify therapeutic targets, even when apparent risk of disease progression is low.

Examining the association between serum galactose-deficient IgA1 and primary IgA nephropathy: a systematic review and meta-analysis.

BACKGROUND: IgA nephropathy (IgAN) is a common primary glomerular disease. The O-glycosylation status of IgA1 plays a crucial role in disease pathophysiology. The level of poorly-O-galactosylated IgA1, or galactose-deficient IgA1 (Gd-IgA1), has also been identified as a potential biomarker in IgAN. We sought to examine the value of serum Gd-IgA1 as a biomarker in IgAN, by investigating its association with clinical, laboratory, and histopathological features of IgAN. METHODS: The review followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations and was registered in PROSPERO (CRD42021287423). The literature search was conducted in PubMed, Web of Science, Cochrane, and Scopus, and the selected articles were evaluated for eligibility based on predefined criteria. The methodological quality of the studies was assessed using the Newcastle-Ottawa Scale. Statistical analysis was performed to calculate effect sizes and assess heterogeneity among the studies. RESULTS: This review analyzed 29 out of 1,986 studies, conducted between 2005 and 2022, with participants from multiple countries. Gd-IgA1 levels were not associated with age and gender, while associations with hypertension, hematuria, and proteinuria were inconsistent. In the meta-analyses, a correlation between serum Gd-IgA1 and estimated glomerular filtration rate was identified, however, the relationships between Gd-IgA1 levels and chronic kidney disease (CKD) stage and progression to kidney failure were inconsistent. CONCLUSIONS: Serum Gd-IgA1 levels were not associated with validated prognostic risk factors, but were negatively correlated with kidney function. Further research in larger studies using standardized assays are needed to establish the value of Gd-IgA1 as a prognostic risk factor in IgAN.

Risk Factors for Thromboembolic Events in Patients With Dialysis-Dependent CKD: Pooled Analysis of Phase 3 Roxadustat Trials in Japan.

INTRODUCTION: Thromboembolic events have occurred in clinical trials of roxadustat. This post hoc analysis explored potential factors related to thromboembolic events in dialysis-dependent patients treated with roxadustat in four phase 3 clinical trials in Japan. METHODS: Thromboembolic events with onset before and after week 12 were evaluated. Baseline risk factors for thromboembolic events were investigated by Cox regression analyses. Nested case-control analyses using conditional logistic models with matched pairs of case-control data explored relationships between thromboembolic events and laboratory parameters. RESULTS: Of the 444 patients, 56 thromboembolic events were observed in 44 patients during ≤ 52 weeks of treatment. The proportion of venous and arterial thromboembolic events gradually increased after week 12. Baseline risk factors included hemodialysis (vs peritoneal dialysis), advanced age (≥ 65 years), shorter dialysis vintage (< 4 months), and history of thromboembolism. The absence of concomitant intravenous or oral iron therapy (including ferric citrate) was associated with thromboembolic events before week 12 (hazard ratio 11.25; 95% confidence interval [CI] 3.36-37.71; vs presence). Case-control analysis revealed that low average transferrin saturation (< 10%; unadjusted odds ratio [OR] 6.25; 95% CI 1.52-25.62; vs ≥ 20%), high average transferrin level (≥ 2.5 g/L; unadjusted OR 4.36; 95% CI 1.23-15.39; vs < 2.0 g/L), and high average roxadustat dose (≥ 150 mg; unadjusted OR 5.95; 95% CI 1.07-33.16; vs < 50 mg) over the previous 8 weeks before the event onset were associated with thromboembolic events after week 12. However, adjustment for iron status extinguished the significant relationship between roxadustat dose and events. Multivariate case-control analysis showed that increased transferrin from baseline (≥ 1.0 g/L; adjusted OR 7.85; 95% CI 1.82-33.90; vs < 0.5 g/dL) and decreased mean corpuscular volume (< - 2 fL; adjusted OR 5.55; 95% CI 1.73-17.83; vs ≥ 0 fL) were associated with increased risk of thromboembolic events. CONCLUSION: In addition to established risk factors, iron deficiency may be related to thromboembolic events. Graphical Abstract available for this article. TRIAL REGISTRATION: NCT02780726, NCT02952092, NCT02780141, NCT02779764.

Roxadustat is an oral medicine that treats anemia in patients with chronic kidney disease (CKD). Thromboembolic events, or blood vessels blocked by a blood clot, have occurred in clinical trials of roxadustat. This study explored potential factors that may be related to thromboembolic events in roxadustat-treated patients with anemia of CKD on dialysis before and after week 12. This study found that hemodialysis (vs peritoneal dialysis), advanced age (older than 65 years), short amount of time on dialysis (less than 4 months), previous history of thromboembolic events, and not receiving iron therapy were risk factors for thromboembolic events before week 12. Iron deficiency and high roxadustat dose were risk factors for thromboembolic events after week 12. When iron status was also considered, we did not find that roxadustat dose was related to thromboembolic events. A different model found that increased levels of transferrin, a protein that transports iron, from baseline and decreased mean corpuscular volume, or smaller red blood cells, increased the risk of thromboembolic events. Patients with anemia of CKD on dialysis may benefit from more intentional monitoring and management of iron while receiving roxadustat.

Risk Factors for Thromboembolic Events in Patients With Dialysis-Dependent CKD: Pooled Analysis of Four Global Roxadustat Phase 3 Trials.

INTRODUCTION: Risk factors for thromboembolic events in patients with dialysis-dependent chronic kidney disease (CKD) receiving roxadustat are unknown. Iron deficiency has been reported as a risk factor for thrombosis in the general population. METHODS: Thromboembolic events with onset before and after week 12 in patients receiving roxadustat were evaluated in this pooled analysis of four global phase 3 trials, PYRENEES, SIERRAS, HIMALAYAS, and ROCKIES. Baseline risk factors for thromboembolic events were investigated by Cox regression analyses. Nested case-control analyses with matched pairs of case-control data explored the relationship between thromboembolic events and last known laboratory parameters before event onset. RESULTS: Of 2354 patients, 1026 thromboembolic events were observed in 568 patients. Baseline risk factors found included hemodialysis (vs peritoneal dialysis), advanced age (≥ 65 years), Black race, high high-sensitivity C-reactive protein, and history of thromboembolism, cardiovascular disease, or diabetes. Univariate case-control analyses revealed that high hemoglobin rate of rise (≥ 0.5 g/dL/week; odds ratio [OR] 2.09; 95% confidence interval [CI] 0.98-4.46) showed a trend towards increased risk of thromboembolic events before week 12, and high rate of hemoglobin decline was associated with events after week 12 (< - 0.5 g/dL/week; OR 3.73; 95% CI 1.68-8.27) as compared to stable hemoglobin levels (≥ - 0.1 to < 0.1 g/dL/week). Multivariate case-control analyses showed that low last known hemoglobin level (< 10 g/dL: adjusted OR 1.91; 95% CI 1.04-3.50; vs ≥ 12 g/dL) and low last known transferrin saturation (TSAT < 10%: adjusted OR 3.78; 95% CI 1.71-8.39; vs ≥ 30%) before event onset were associated with events after week 12. In patients with last known TSAT < 30%, higher roxadustat dose was associated with thromboembolic events; however, no association was observed in those with TSAT ≥ 30%. CONCLUSIONS: Among various risk factors for thromboembolic events, it is reasonable to avoid a rapid increase and decline in hemoglobin levels as well as ensure TSAT ≥ 30%, rather than increasing the roxadustat dose. Graphical Abstract available for this article. TRIAL REGISTRATION: NCT02278341, NCT02273726, NCT02052310, NCT02174731.

Roxadustat is an oral treatment for patients with anemia, or low hemoglobin levels, due to chronic kidney disease. Thromboembolic events are caused by a blood clot blocking blood vessels, and they have occurred in clinical trials of roxadustat. This analysis evaluated risk factors for thromboembolic events in patients receiving roxadustat to treat anemia of chronic kidney disease who are on dialysis. Two different statistical approaches were used to investigate risk factors for thromboembolic events that occurred before and after 12 weeks of roxadustat treatment. We found that rapid improvement of anemia after starting roxadustat treatment may be associated with an increased risk of thromboembolic events occurring in the first 12 weeks of treatment. In contrast, severe anemia or worsening of anemia was associated with an increased risk of thromboembolic events after week 12. Low iron levels in the blood or greater decline of available iron in the blood from baseline were also detected as risk factors for the events after week 12, suggesting that iron supplementation is important in patients who are iron-deficient. Moreover, thromboembolic events were also associated with older age (≥ 65 years), Black race, high levels of inflammation, and having had a previous thromboembolic event or having a history of cardiovascular disease or diabetes. Some risk factors, such as iron status and hemoglobin levels, can be changed after beginning roxadustat treatment and should be monitored and modified, as needed.

Novel Treatment Paradigms: Primary IgA Nephropathy.

IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. Approximately 30% to 45% of patients progress to kidney failure (KF) within 20 to 25 years of diagnosis, and there has long been a lack of effective treatments. The therapeutic landscape in IgAN is rapidly evolving, driven in large part by the acceptance of the surrogate clinical trial end point of proteinuria reduction by regulatory authorities for the accelerated approval of new therapies. Two drugs, targeted release formulation (TRF)-budesonide (nefecon) and sparsentan, have recently been approved under this scheme. Advancing insights into the pathophysiology of IgAN, including the roles of the mucosal immune system, B-cells, the complement system, and the endothelin system have driven development of therapies that target these factors. This review outlines current, recently approved, and emerging therapies for IgAN.

An Update on Current Therapeutic Options in IgA Nephropathy.

Immunoglobulin A nephropathy (IgAN) remains the leading cause of primary glomerular disease worldwide. Outcomes are poor with high rates of progressive chronic kidney disease and kidney failure, which contributes to global healthcare costs. Although this disease entity has been described, there were no disease-specific treatments until recently, with the current standard of care focusing on optimal supportive measures including lifestyle modifications and optimization of the renin-angiotensin-aldosterone blockade. However, with significant advances in the understanding of the pathogenesis of IgAN in the past decade, and the acceptance of surrogate outcomes for accelerated drug approval, there have been many new investigational agents tested to target this disease. As these agents become available, we envision a multi-pronged treatment strategy that simultaneously targets the consequences of ongoing nephron loss, stopping any glomerular inflammation, inhibiting pro-fibrotic signals in the glomerulus and tubulo-interstitium, and inhibiting the production of pathogenic IgA molecules. This review is an update on a previous review published in 2021, and we aim to summarize the developments and updates in therapeutic strategies in IgAN and highlight the promising discoveries that are likely to add to our armamentarium.

Phase 2 Trial of Cemdisiran in Adult Patients with IgA Nephropathy: A Randomized Controlled Trial.

BACKGROUND: IgA nephropathy is the most common primary GN. Clinical features of IgA nephropathy include proteinuria, which is the strongest known surrogate of progression to kidney failure. Complement pathway activation is a critical driver of inflammation and tissue injury in IgA nephropathy. Cemdisiran is an investigational RNA interference therapeutic that suppresses hepatic production of complement component 5 (C5), thereby potentially reducing proteinuria in IgA nephropathy. We evaluated the efficacy and safety of cemdisiran in adult patients with IgA nephropathy at high risk of kidney disease progression. METHODS: In this phase 2, 36-week, double-blind study, adult patients with IgA nephropathy and urine protein ≥1 g/24 hours were randomized (2:1) to subcutaneous cemdisiran 600 mg or placebo every 4 weeks in combination with the standard of care. The primary end point was percentage change from baseline at week 32 in urine protein-to-creatinine ratio (UPCR) measured by 24-hour urine collection. Additional end points included change from baseline in UPCR measured by spot urine, serum C5 level, and safety assessments. RESULTS: Thirty-one patients were randomized (cemdisiran, N =22; placebo, N =9). Cemdisiran-treated patients had a placebo-adjusted geometric mean change in 24-hour UPCR of -37.4% (cemdisiran-adjusted geometric mean ratio to baseline [SEM], 0.69 [0.10]) at week 32. Spot UPCR was consistent with 24-hour UPCR placebo-adjusted change of -45.8% (cemdisiran-adjusted geometric mean ratio to baseline [SEM], 0.73 [0.11]). Mean (SD) change in serum C5 level from baseline at week 32 was -98.7% (1.2) with cemdisiran and 25.2% (57.7) with placebo. Over 36 weeks, most adverse events were mild or moderate and transient; the most common adverse event after cemdisiran treatment was injection-site reaction (41%). CONCLUSIONS: These findings indicate that treatment with cemdisiran resulted in a reduction of proteinuria at week 32 and was well tolerated.

Detection of PatIent-Level distances from single cell genomics and pathomics data with Optimal Transport (PILOT).

Although clinical applications represent the next challenge in single-cell genomics and digital pathology, we still lack computational methods to analyze single-cell or pathomics data to find sample-level trajectories or clusters associated with diseases. This remains challenging as single-cell/pathomics data are multi-scale, i.e., a sample is represented by clusters of cells/structures, and samples cannot be easily compared with each other. Here we propose PatIent Level analysis with Optimal Transport (PILOT). PILOT uses optimal transport to compute the Wasserstein distance between two individual single-cell samples. This allows us to perform unsupervised analysis at the sample level and uncover trajectories or cellular clusters associated with disease progression. We evaluate PILOT and competing approaches in single-cell genomics or pathomics studies involving various human diseases with up to 600 samples/patients and millions of cells or tissue structures. Our results demonstrate that PILOT detects disease-associated samples from large and complex single-cell or pathomics data. Moreover, PILOT provides a statistical approach to find changes in cell populations, gene expression, and tissue structures related to the trajectories or clusters supporting interpretation of predictions.

Results of a randomized double-blind placebo-controlled Phase 2 study propose iptacopan as an alternative complement pathway inhibitor for IgA nephropathy.

Targeting the alternative complement pathway is an attractive therapeutic strategy given its role in the pathogenesis of immunoglobulin A nephropathy (IgAN). Iptacopan (LNP023) is an oral, proximal alternative complement inhibitor that specifically binds to Factor B. Our randomized, double-blind, parallel-group adaptive Phase 2 study (NCT03373461) enrolled patients with biopsy-confirmed IgAN (within previous three years) with estimated glomerular filtration rates of 30 mL/min/1.73 m2 and over and urine protein 0.75 g/24 hours and over on stable doses of renin angiotensin system inhibitors. Patients were randomized to four iptacopan doses (10, 50, 100, or 200 mg bid) or placebo for either a three-month (Part 1; 46 patients) or a six-month (Part 2; 66 patients) treatment period. The primary analysis evaluated the dose-response relationship of iptacopan versus placebo on 24-hour urine protein-to-creatinine ratio (UPCR) at three months. Other efficacy, safety and biomarker parameters were assessed. Baseline characteristics were generally well-balanced across treatment arms. There was a statistically significant dose-response effect, with 23% reduction in UPCR achieved with iptacopan 200 mg bid (80% confidence interval 8-34%) at three months. UPCR decreased further through six months in iptacopan 100 and 200 mg arms (from a mean of 1.3 g/g at baseline to 0.8 g/g at six months in the 200 mg arm). A sustained reduction in complement biomarker levels including plasma Bb, serum Wieslab, and urinary C5b-9 was observed. Iptacopan was well-tolerated, with no reports of deaths, treatment-related serious adverse events or bacterial infections, and led to strong inhibition of alternative complement pathway activity and persistent proteinuria reduction in patients with IgAN. Thus, our findings support further evaluation of iptacopan in the ongoing Phase 3 trial (APPLAUSE-IgAN; NCT04578834).

A Phase 2 Trial of Sibeprenlimab in Patients with IgA Nephropathy.

BACKGROUND: A proliferation-inducing ligand (APRIL) is implicated in the pathogenesis of IgA nephropathy. Sibeprenlimab is a humanized IgG2 monoclonal antibody that binds to and neutralizes APRIL. METHODS: In this phase 2, multicenter, double-blind, randomized, placebo-controlled, parallel-group trial, we randomly assigned adults with biopsy-confirmed IgA nephropathy who were at high risk for disease progression, despite having received standard-care treatment, in a 1:1:1:1 ratio to receive intravenous sibeprenlimab at a dose of 2, 4, or 8 mg per kilogram of body weight or placebo once monthly for 12 months. The primary end point was the change from baseline in the log-transformed 24-hour urinary protein-to-creatinine ratio at month 12. Secondary end points included the change from baseline in the estimated glomerular filtration rate (eGFR) at month 12. Safety was also assessed. RESULTS: Among 155 patients who underwent randomization, 38 received sibeprenlimab at a dose of 2 mg per kilogram, 41 received sibeprenlimab at a dose of 4 mg per kilogram, 38 received sibeprenlimab at a dose of 8 mg per kilogram, and 38 received placebo. At 12 months, the geometric mean ratio reduction (±SE) from baseline in the 24-hour urinary protein-to-creatinine ratio was 47.2±8.2%, 58.8±6.1%, 62.0±5.7%, and 20.0±12.6% in the sibeprenlimab 2-mg, 4-mg, and 8-mg groups and the placebo group, respectively. At 12 months, the least-squares mean (±SE) change from baseline in eGFR was -2.7±1.8, 0.2±1.7, -1.5±1.8, and -7.4±1.8 ml per minute per 1.73 m2 in the sibeprenlimab 2-mg, 4-mg, and 8-mg groups and the placebo group, respectively. The incidence of adverse events that occurred after the start of administration of sibeprenlimab or placebo was 78.6% in the pooled sibeprenlimab groups and 71.1% in the placebo group. CONCLUSIONS: In patients with IgA nephropathy, 12 months of treatment with sibeprenlimab resulted in a significantly greater decrease in proteinuria than placebo. (Funded by Visterra; ENVISION ClinicalTrials.gov number, NCT04287985; EudraCT number, 2019-002531-29.).

The contribution of a proliferation-inducing ligand (APRIL) and other TNF superfamily members in pathogenesis and progression of IgA nephropathy.

Advances in our understanding of the pathogenesis of immunoglobulin A nephropathy (IgAN) have led to the identification of novel therapeutic targets and potential disease-specific treatments. Specifically, a proliferation-inducing ligand (APRIL) has been implicated in the pathogenesis of IgAN, mediating B-cell dysregulation and overproduction of pathogenic galactose-deficient IgA1 (Gd-IgA1). Animal and clinical studies support the involvement of APRIL in the pathogenesis and progression of IgAN. An elevated level of APRIL is found in IgAN when compared with controls, which correlates with the level of Gd-IgA1 and associates with more severe disease presentation and worse outcomes. Conversely, anti-APRIL therapy reduces pathogenic Gd-IgA1 and IgA immune complex formation and ameliorates the severity of kidney inflammation and injury. Genome-wide association studies in IgAN have identified TNFSF13 and TNFRSF13B, a cytokine ligand-receptor gene pair encoding APRIL and its receptor, respectively, as risk susceptibility loci in IgAN, further supporting the causal role of the APRIL signalling pathway in IgAN. Several novel experimental agents targeting APRIL, including atacicept, telitacicept, zigakibart and sibeprenlimab, are currently under investigation as potential therapies in IgAN. Preliminary results suggest that these agents are well-tolerated, and reduce levels of Gd-IgA1, with corresponding improvement in proteinuria. Further studies are ongoing to confirm the safety and efficacy of anti-APRIL approaches as an effective therapeutic strategy in IgAN.

Randomized Trial on the Effect of an Oral Spleen Tyrosine Kinase Inhibitor in the Treatment of IgA Nephropathy.

Introduction: We reported increased spleen tyrosine kinase (SYK) expression in kidney biopsies of patients with IgA nephropathy (IgAN) and that inhibition of SYK reduces inflammatory cytokines production from IgA stimulated mesangial cells. Methods: This study was a double-blind, randomized, placebo-controlled phase 2 trial of fostamatinib (an oral SYK inhibitor) in 76 patients with IgAN. Patients were randomized to receive placebo, fostamatinib at 100 mg or 150 mg twice daily for 24 weeks on top of maximum tolerated dose of renin-angiotensin system inhibitors. The primary end point was reduction of proteinuria. Secondary end points included change from baseline in estimated glomerular filtration rate (eGFR) and kidney histology. Results: Although we could not detect significant reduction in proteinuria with fostamatinib overall, in a predetermined subgroup analysis, there was a trend for dose-dependent reduction in median proteinuria (from baseline to 24 weeks by 14%, 27%, and 36% in the placebo, fostamatinib 100 mg, and 150 mg groups, respectively) in patients with baseline urinary protein-to-creatinine ratios (UPCR) more than 1000 mg/g. Kidney function (eGFR) remained stable in all groups. Fostamatinib was well-tolerated. Side effects included diarrhea, hypertension, and increased liver enzymes. Thirty-nine patients underwent repeat biopsy showing reductions in SYK staining associated with therapy at low dose (-1.5 vs. 1.7 SYK+ cells/glomerulus in the placebo group, P < 0.05). Conclusions: There was a trend toward reduction in proteinuria with fostamatinib in a predefined analysis of high risk patients with IgAN despite maximal care, as defined by baseline UPCR greater than 1000 mg/g. Further study may be warranted.

Conditional power and information fraction calculations at an interim analysis for random coefficient models.

Random coefficient (RC) models are commonly used in clinical trials to estimate the rate of change over time in longitudinal data. Trials utilizing a surrogate endpoint for accelerated approval with a confirmatory longitudinal endpoint to show clinical benefit is a strategy implemented across various therapeutic areas, including immunoglobulin A nephropathy. Understanding conditional power (CP) and information fraction calculations of RC models may help in the design of clinical trials as well as provide support for the confirmatory endpoint at the time of accelerated approval. This paper provides calculation methods, with practical examples, for determining CP at an interim analysis for a RC model with longitudinal data, such as estimated glomerular filtration rate (eGFR) assessments to measure rate of change in eGFR slope.