Plasma Oxalate Research Articles

Sel1-like proteins and peptides are the major Oxalobacter formigenes-derived factors stimulating oxalate transport by human intestinal epithelial cells.

Kidney stones (KSs) are very common, excruciating, and associated with tremendous healthcare cost, chronic kidney disease (CKD), and kidney failure (KF). Most KSs are composed of calcium oxalate and small increases in urinary oxalate concentration significantly enhance the stone risk. Oxalate also potentially contributes to CKD progression, kidney disease-associated cardiovascular diseases, and poor renal allograft survival. This emphasizes the urgent need for plasma and urinary oxalate lowering therapies, which can be achieved by enhancing enteric oxalate secretion. We previously identified Oxalobacter formigenes (O. formigenes)-derived factors secreted in its culture-conditioned medium (CM), which stimulate oxalate transport by human intestinal Caco2-BBE (C2) cells and reduce urinary oxalate excretion in hyperoxaluric mice by enhancing colonic oxalate secretion. Given their remarkable therapeutic potential, we now identified Sel1-like proteins as the major O. formigenes-derived secreted factors using mass spectrometry and functional assays. Crystal structures for six proteins were determined to confirm structures and better understand functions. OxBSel1-14-derived small peptides P8 and P9 were identified as the major factors, with P8 + 9 closely recapitulating the CM's effects, acting through the oxalate transporters SLC26A2 and SLC26A6 and PKA activation. Besides C2 cells, P8 + 9 also stimulate oxalate transport by human ileal and colonic organoids, confirming that they work in human tissues. In conclusion, P8 and P9 peptides are identified as the major O. formigenes-derived secreted factors and they have significant therapeutic potential for hyperoxalemia, hyperoxaluria, and related disorders, impacting the outcomes of patients suffering from KSs, enteric hyperoxaluria, primary hyperoxaluria, CKD, KF, and renal transplant recipients.NEW & NOTEWORTHY We previously identified Oxalobacter formigenes-derived secreted factors stimulating oxalate transport by human intestinal epithelial cells in vitro and reducing urinary oxalate excretion in hyperoxaluric mice by enhancing colonic oxalate secretion. We now identified Sel1-like proteins and small peptides as the major secreted factors and they have significant therapeutic potential for hyperoxalemia and hyperoxaluria, impacting the outcomes of patients suffering from kidney stones, primary and secondary hyperoxaluria, chronic kidney disease, kidney failure, and renal transplant recipients.

Four novel variants identified in primary hyperoxaluria and genotypic and phenotypic analysis in 21 Chinese patients.

Background: Primary hyperoxaluria (PH) is a rare genetic disorder characterized by excessive accumulation of oxalate in plasma and urine, resulting in various phenotypes due to allelic and clinical heterogeneity. This study aimed to analyze the genotype of 21 Chinese patients with primary hyperoxaluria (PH) and explore their correlations between genotype and phenotype. Methods: Combined with clinical phenotypic and genetic analysis, we identified 21PH patients from highly suspected Chinese patients. The clinical, biochemical, and genetic data of the 21 patients were subsequently reviewed. Results: We reported 21 cases of PH in China, including 12 cases of PH1, 3 cases of PH2 and 6 cases of PH3, and identified 2 novel variants (c.632T > G and c.823_824del) in AGXT gene and 2 novel variants (c.258_272del and c.866-34_866-8del) in GRHPR gene, respectively. A possible PH3 hotspot variant c.769T > G was identified for the first time. In addition, patients with PH1 showed higher levels of creatinine and lower eGFR than those with PH2 and PH3. In PH1, patients with severe variants in both alleles had significantly higher creatinine and lower eGFR than other patients. Delayed diagnosis still existed in some late-onset patients. Of all cases, 6 had reached to end-stage kidney disease (ESKD) at diagnosis with systemic oxalosis. Five patients were on dialysis and three had undergone kidney or liver transplants. Notably, four patients showed a favorable therapeutic response to vitamin B6, and c.823_824dup and c.145A > C may be identified as potentially vitamin B6-sensitive genotypes. Conclusion: In brief, our study identified 4 novel variants and extended the variant spectrum of PH in the Chinese population. The clinical phenotype was characterized by large heterogeneity, which may be determined by genotype and a variety of other factors. We first reported two variants that may be sensitive to vitamin B6 therapy in Chinese population, providing valuable references for clinical treatment. In addition, early screening and prognosis of PH should be given more attention. We propose to establish a large-scale registration system for rare genetic diseases in China and call for more attention on rare kidney genetic diseases.

MP10-01 EFFICACY AND SAFETY OF LUMASIRAN IN PATIENTS WITH PRIMARY HYPEROXALURIA TYPE 1: 36-MONTH ANALYSIS OF THE ILLUMINATE-A TRIAL

You have accessJournal of UrologyCME1 Apr 2023MP10-01 EFFICACY AND SAFETY OF LUMASIRAN IN PATIENTS WITH PRIMARY HYPEROXALURIA TYPE 1: 36-MONTH ANALYSIS OF THE ILLUMINATE-A TRIAL John Lieske, Jeffrey Saland, Jaap Groothoff, Yaacov Frishberg, Hadas Shasha-Lavsky, Daniella Magen, Shabbir Moochhala, Eva Simkova, Martin Coenen, Wesley Hayes, Julien Hogan, Anne-Laure Sellier-Leclerc, Yinggu Bao, John Gansner, and Sally-Anne Hulton John Lieske John Lieske More articles by this author , Jeffrey SalandJeffrey Saland More articles by this author , Jaap GroothoffJaap Groothoff More articles by this author , Yaacov FrishbergYaacov Frishberg More articles by this author , Hadas Shasha-LavskyHadas Shasha-Lavsky More articles by this author , Daniella MagenDaniella Magen More articles by this author , Shabbir MoochhalaShabbir Moochhala More articles by this author , Eva SimkovaEva Simkova More articles by this author , Martin CoenenMartin Coenen More articles by this author , Wesley HayesWesley Hayes More articles by this author , Julien HoganJulien Hogan More articles by this author , Anne-Laure Sellier-LeclercAnne-Laure Sellier-Leclerc More articles by this author , Yinggu BaoYinggu Bao More articles by this author , John GansnerJohn Gansner More articles by this author , and Sally-Anne HultonSally-Anne Hulton More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003225.01AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Primary hyperoxaluria type 1 (PH1) is a rare genetic disease characterized by hepatic oxalate overproduction leading to kidney stones and progressive kidney disease. Lumasiran is an RNAi therapeutic approved for the treatment of PH1 to lower urinary oxalate (UOx) and plasma oxalate levels in pediatric and adult patients. Here, we report data from the 36-month (M) analysis of ILLUMINATE-A, a Phase 3 trial of lumasiran (NCT03681184). METHODS: ILLUMINATE-A is an ongoing Phase 3 trial in patients age ≥6 years with genetically confirmed PH1 and an estimated glomerular filtration rate (eGFR) ≥30 mL/min/1.73 m2. A 6M double-blind, placebo-controlled primary analysis period is followed by an extension period (up to 54M) in which all patients receive lumasiran. RESULTS: Of 39 patients enrolled, 24/26 in the lumasiran/lumasiran group and 13/13 in the placebo/lumasiran group entered and continue in the extension period. Mean 24-hour UOx reduction at M36 relative to baseline was 63% in the lumasiran/lumasiran group and 55% in the placebo/lumasiran group (M30 post–lumasiran initiation). At M36, the proportion of patients achieving 24-hour UOx excretion ≤1.5× upper limit of normal was 76% in the lumasiran/lumasiran group and 92% in the placebo/lumasiran group. Mean baseline-to-M36 reductions in plasma oxalate were 36% and 37% in the lumasiran/lumasiran and placebo/lumasiran groups, respectively. In both groups, eGFR remained stable through M36. Kidney stone event rates decreased from 3.19/person-year during the 12M before consent to 0.70/person-year in the lumasiran/lumasiran group and from 0.54/person-year to 0.39/person-year in the placebo/lumasiran group. Medullary nephrocalcinosis generally remained stable or improved. The most common lumasiran-related adverse events were mild injection-site reactions (36% of patients). CONCLUSIONS: Long-term treatment with lumasiran led to sustained UOx reduction through M36, with an acceptable safety profile in patients with PH1 and encouraging clinical outcomes data. Source of Funding: Alnylam Pharmaceuticals © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e114 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information John Lieske More articles by this author Jeffrey Saland More articles by this author Jaap Groothoff More articles by this author Yaacov Frishberg More articles by this author Hadas Shasha-Lavsky More articles by this author Daniella Magen More articles by this author Shabbir Moochhala More articles by this author Eva Simkova More articles by this author Martin Coenen More articles by this author Wesley Hayes More articles by this author Julien Hogan More articles by this author Anne-Laure Sellier-Leclerc More articles by this author Yinggu Bao More articles by this author John Gansner More articles by this author Sally-Anne Hulton More articles by this author Expand All Advertisement PDF downloadLoading ...

Prospective Assessment of the Prevalence of Enter Hyperoxalosis in Kidney Transplant Candidates.

We prospectively measured POx among KT candidates evaluated at our center from 2017 to 2020 with risk factors for EH namely bariatric surgery, inflammatory bowel disease, or cystic fibrosis. EH was defined by a POx ≥10 μmol/L. Period-prevalence of EH was calculated. We compared mean POx across 5 factors: underlying condition, chronic kidney disease (CKD) stage, dialysis modality, phosphate binder type, and body mass index. Of 40 KT candidates screened, 23 had EH for a 4-y period prevalence of 58%. Mean POx was 21.6 ± 23.5 μmol/L ranging from 0 to 109.6 μmol/L. 40% of screened had POx >20 μmol/L. Sleeve gastrectomy was the most common underlying condition associated with EH. Mean POx did not differ by underlying condition (P = 0.27), CKD stage (P = 0.17), dialysis modality (P = 0.68), phosphate binder (P = 0.58), and body mass index (P = 0.56). Bariatric surgery and inflammatory bowel disease were associated with a high prevalence of EH among KT candidates. Contrary to prior studies, sleeve gastrectomy was also associated with hyperoxalosis in advanced CKD. POx concentrations observed in EH reached levels associated with tissue and potentially allograft deposition. Concentrations can be as high as that seen in primary hyperoxaluria. More studies are needed to assess if POx is indeed a modifiable factor affecting allograft function in patients with EH.

Plasma oxalate and glycolate concentrations in dialysis patients with and without primary hyperoxaluria type 1.

Plasma oxalate and glycolate concentrations in dialysis patients with and without primary hyperoxaluria type 1.

Characteristics and Graft Outcomes of Kidney Transplant Candidates with Enteric Risk Factors and Elevated Plasma Oxalate Levels

Introduction: This study describes patient characteristics and examines graft function of kidney transplant recipients (without primary hyperoxaluria) with elevated plasma oxalate (POx) and enteric risk factors prior to transplant at our institution. Methods: Kidney transplant recipients between 2012 and 2020 with elevated POx at the time of kidney transplant evaluation were included. A matched control cohort was gathered using patient/donor age, living/deceased donor type, panel reactive antibody, kidney donor profile index, and human leukocyte antigen mismatch as matching variables. Graft function at 1 year and at last follow-up was reported. Results: A total of 106 patients with elevated POx were identified. A third of the patients had Roux-en-Y gastric bypass, a third had other enteric risks, and a third did not have an identifiable enteric risk. Median eGFR (estimated glomerular filtration rate) at 1 year and at last follow-up was similar between cases and controls except for subgroup of patients with pre-transplant POx >30 µmol/L where 1-year eGFR was lower compared to controls. Across eGFR categories, more cases were in eGFR category <30 mL/min/1.73 m² compared to controls. Conclusion: Roux-en-Y gastric bypass is the most common identifiable risk for elevated POx in kidney transplant candidates. 1-year graft function was not inferior in cases compared to matched controls except for subgroup with POx >30 µmol/L pre-transplant.

Three Tesla magnetic resonance imaging detects oxalate osteopathy in patients with primary hyperoxaluria type I.

With declining kidney function and therefore increasing plasma oxalate, patients with primary hyperoxaluria type I (PHI) are at risk to systemically deposit calcium-oxalate crystals. This systemic oxalosis may occur even at early stages of chronic kidney failure (CKD) but is difficult to detect with non-invasive imaging procedures. We tested if magnetic resonance imaging (MRI) is sensitive to detect oxalate deposition in bone. A 3 Tesla MRI of the left knee/tibial metaphysis was performed in 46 patients with PHI and in 12 healthy controls. In addition to the investigator's interpretation, signal intensities (SI) within a region of interest (ROI, transverse images below the level of the physis in the proximal tibial metaphysis) were measured pixelwise, and statistical parameters of their distribution were calculated. In addition, 52 parameters of texture analysis were evaluated. Plasma oxalate and CKD status were correlated to MRI findings. MRI was then implemented in routine practice. Independent interpretation by investigators was consistent in most cases and clearly differentiated patients from controls. Statistically significant differences were seen between patients and controls (p < 0.05). No correlation/relation between the MRI parameters and CKD stages or Pox levels was found. However, MR imaging of oxalate osteopathy revealed changes attributed to clinical status which differed clearly to that in secondary hyperparathyroidism. MRI is able to visually detect (early) oxalate osteopathy in PHI. It can be used for its monitoring and is distinguished from renal osteodystrophy. In the future, machine learning algorithms may aid in the objective assessment of oxalate deposition in bone. Graphical Abstract A higher resolution version of the Graphical abstract is available as Supplementary information.

Oxalate homeostasis.

Oxalate homeostasis is maintained through a delicate balance between endogenous sources, exogenous supply and excretion from the body. Novel studies have shed light on the essential roles of metabolic pathways, the microbiome, epithelial oxalate transporters, and adequate oxalate excretion to maintain oxalate homeostasis. In patients with primary or secondary hyperoxaluria, nephrolithiasis, acute or chronic oxalate nephropathy, or chronic kidney disease irrespective of aetiology, one or more of these elements are disrupted. The consequent impairment in oxalate homeostasis can trigger localized and systemic inflammation, progressive kidney disease and cardiovascular complications, including sudden cardiac death. Although kidney replacement therapy is the standard method for controlling elevated plasma oxalate concentrations in patients with kidney failure requiring dialysis, more research is needed to define effective elimination strategies at earlier stages of kidney disease. Beyond well-known interventions (such as dietary modifications), novel therapeutics (such as small interfering RNA gene silencers, recombinant oxalate-degrading enzymes and oxalate-degrading bacterial strains) hold promise to improve the outlook of patients with oxalate-related diseases. In addition, experimental evidence suggests that anti-inflammatory medications might represent another approach to mitigating or resolving oxalate-induced conditions.

Quantification of Oxalate in Human Plasma by Novel Liquid Chromatography-Tandem Mass Spectrometry: Method Development, Validation, and Application in Lumasiran Clinical Trials

Quantification of Oxalate in Human Plasma by Novel Liquid Chromatography-Tandem Mass Spectrometry: Method Development, Validation, and Application in Lumasiran Clinical Trials

Efficacy of chlorogenic acid against ethylene glycol-induced renal stone model: The role of NFKB-RUNX2-AP1-OSTERIX signaling pathway

Background and objectiveRenal tissue injuries by free radicals are an essential reason in pathogenesis of urinary tract stones. Ethylene glycol is one of the toxic agents which can causes to the increases in biosynthesis of reactive oxygen species and oxidative stress condition. Natural antioxidants have been reported to protective efficacy against renal stones formation. Accordingly, the aim of the current experiment was to identify the renal protective effect of chlorogenic acid as a well-prominent antioxidant on ethylene glycol-induced renal stone model targeting the NFKB-RUNX2-AP1-OSTERIX signaling pathway. Materials and methodsRenal stones model were established by ethylene glycol (Percent: 0.75) within the daily drinking water for rats. Treatment groups received cystone (750 mg/kg) and chlorogenic acid (100, 200, and 400 mg/kg, day: 15th to 28th, gavage). After 4 weeks, the renal function parameters (calcium, uric acid, creatinine, total protein, oxalate, and citrate) in plasma, urine, and renal tissue were measured. Moreover, oxidative stress factors and gene expression of NFKB, RUNX2, AP1, and OSTERIX were also evaluated. ResultsThe results showed improved renal function in chlorogenic acid-treated groups. The total proteins and creatinine excretion were decreased. Also the gene expression of oxidative stress pathway (NFKB-RUNX2-AP1-OSTERIX) were decreased which caused to increases of antioxidant enzymes. Conclusionsthe antioxidant activity increases by chlorogenic acid treatment may have a critical role in prevention of calcium oxalate formation via inhibition of the NFKB-RUNX2-AP1-OSTERIX signaling pathway.

The retinal phenotype in primary hyperoxaluria type 2 and 3

BackgroundThe primary hyperoxalurias (PH1-3) are rare inherited disorders of the glyoxylate metabolism characterized by endogenous overproduction of oxalate. As oxalate cannot be metabolized by humans, oxalate deposits may affect various organs, primarily the kidneys, bones, heart, and eyes. Vision loss induced by severe retinal deposits is commonly seen in infantile PH1; less frequently and milder retinal alterations are found in non-infantile PH1. Retinal disease has not systematically been investigated in patients with PH2 and PH3.MethodsA comprehensive ophthalmic examination was performed in 19 genetically confirmed PH2 (n = 7) and PH3 (n = 12) patients (median age 11 years, range 3–59).ResultsMedian best corrected visual acuity was 20/20. In 18 patients, no retinal oxalate deposits were found. A 30-year-old male with PH2 on maintenance hemodialysis with plasma oxalate (Pox) elevation (> 100 µmol/l; normal < 7.4) demonstrated bilateral drusen-like, hyperreflective deposits which were interpreted as crystallized oxalate. Two siblings of consanguineous parents with PH2 presented with retinal degeneration and vision loss; exome-wide analysis identified a second monogenic disease, NR2E3-associated retinal dystrophy.ConclusionsRetinal disease manifestation in PH2 and PH3 is rare but mild changes can occur at least in PH2-associated kidney failure. Decline in kidney function associated with elevated plasma oxalate levels could increase the risk of systemic oxalosis. Deep phenotyping combined with genomic profiling is vital to differentiate extrarenal disease in multisystem disorders such as PH from independent inherited (retinal) disease.Graphical abstractA higher resolution version of the Graphical abstract is available as Supplementary information

Chronic liver disease and hepatic calcium-oxalate deposition in patients with primary hyperoxaluria type I

Patients with primary hyperoxaluria type I (PH I) are prone to develop early kidney failure. Systemic deposition of calcium-oxalate (CaOx) crystals starts, when renal function declines and plasma oxalate increases. All tissue, but especially bone, heart and eyes are affected. However, liver involvement, as CaOx deposition or chronic hepatitis/fibrosis has never been reported. We examined liver specimen from 19 PH I patients (aged 1.5 to 52 years at sample collection), obtained by diagnostic biopsy (1), at autopsy (1), or transplantation (17). With polarization microscopy, birefringent CaOx crystals located in small arteries, but not within hepatocytes were found in 3/19 patients. Cirrhosis was seen in one, fibrosis in 10/19 patients, with porto-portal and nodular fibrosis (n = 1), with limitation to the portal field in 8 and/or to central areas in 5 patients. Unspecific hepatitis features were observed in 7 patients. Fiber proliferations were detectable in 10 cases and in one sample transformed Ito-cells (myofibroblasts) were found. Iron deposition, but also megakaryocytes as sign of extramedullary erythropoiesis were found in 9, or 3 patients, respectively. Overall, liver involvement in patients with PH I was more pronounced, as previously described. However, CaOx deposition was negligible in liver, although the oxalate concentration there must be highest.

Application of multivariate joint modeling of longitudinal biomarkers and time-to-event data to a rare kidney stone cohort.

Time-dependent Cox proportional hazards regression is a popular statistical method used in kidney disease research to evaluate associations between biomarkers collected serially over time with progression to kidney failure. Typically, biomarkers of interest are considered time-dependent covariates being updated at each new measurement using last observation carried forward (LOCF). Recently, joint modeling has emerged as a flexible alternative for multivariate longitudinal and time-to-event data. This study describes and demonstrates multivariate joint modeling using as an example the association of serial biomarkers (plasma oxalate [POX] and urinary oxalate [UOX]) and kidney function among patients with primary hyperoxaluria in the Rare Kidney Stone Consortium Registry. Time-to-kidney failure was regressed on serially measured biomarkers in two ways: time-dependent LOCF Cox proportional hazards regression and multivariate joint models. In time-dependent LOCF Cox regression, higher POX was associated with increased risk of kidney failure (HR = 2.20 per doubling, 95% CI = [1.38-3.51], p < 0.001) whereas UOX was not (HR = 1.08 per doubling, [0.66-1.77], p = 0.77). In multivariate joint models, estimates suggest higher UOX may be associated with lower risk of kidney failure (HR = 0.42 per doubling [0.15-1.04], p = 0.066), though not statistically significant, since impaired urinary excretion of oxalate may reflect worsening kidney function. Multivariate joint modeling is more flexible than LOCF and may better reflect biological plausibility since biomarkers are not steady-state values between measurements. While LOCF is preferred to naïve methods not accounting for changes in biomarkers over time, results may not accurately reflect flexible relationships that can be captured with multivariate joint modeling.

PHYOX2: a pivotal randomized study of nedosiran in primary hyperoxaluria type 1 or 2

Nedosiran is an investigational RNA interference agent designed to inhibit expression of hepatic lactate dehydrogenase, the enzyme thought responsible for the terminal step of oxalate synthesis. Oxalate overproduction is the hallmark of all genetic subtypes of primary hyperoxaluria (PH). In this double-blind, placebo-controlled study, we randomly assigned (2:1) 35 participants with PH1 (n= 29) or PH2 (n= 6) with eGFR≥30 mL/min/1.73 m2 to subcutaneous nedosiran or placebo once monthly for 6 months. The area under the curve (AUC) of percent reduction from baseline in 24-hour urinary oxalate (Uox) excretion (primary endpoint), between day 90-180, was significantly greater with nedosiran vs placebo (least squares mean [SE],+3507 [788] vs-1664 [1190], respectively; difference, 5172; 95% CI 2929-7414; P< 0.001). A greater proportion of participants receiving nedosiran vs placebo achieved normal or near-normal (<0.60 mmol/24 hours;<1.3× ULN) Uox excretion on≥2 consecutive visits starting at day 90 (50% vs 0; P= 0.002); this effect was mirrored in the nedosiran-treated PH1 subgroup (64.7% vs 0; P< 0.001). The PH1 subgroup maintained a sustained Uox reduction while on nedosiran, whereas no consistent effect was seen in the PH2 subgroup. Nedosiran-treated participants with PH1 also showed a significant reduction in plasma oxalate versus placebo (P= 0.017). Nedosiran was generally safe and well tolerated. In the nedosiran arm, the incidence of injection-site reactions was 9% (all mild and self-limiting). In conclusion, participants with PH1 receiving nedosiran had clinically meaningful reductions in Uox, the mediator of kidney damage in PH.

Efficacy and safety of lumasiran for infants and young children with primary hyperoxaluria type 1: 12-month analysis of the phase 3 ILLUMINATE-B trial

BackgroundPrimary hyperoxaluria type 1 (PH1) is a rare genetic disease that causes progressive kidney damage and systemic oxalosis due to hepatic overproduction of oxalate. Lumasiran demonstrated efficacy and safety in the 6-month primary analysis period of the phase 3, multinational, open-label, single-arm ILLUMINATE-B study of infants and children < 6 years old with PH1 (ClinicalTrials.gov: NCT03905694 (4/1/2019); EudraCT: 2018–004,014-17 (10/12/2018)). Outcomes in the ILLUMINATE-B extension period (EP) for patients who completed ≥ 12 months on study are reported here.MethodsOf the 18 patients enrolled in the 6-month primary analysis period, all entered the EP and completed ≥ 6 additional months of lumasiran treatment (median (range) duration of total exposure, 17.8 (12.7–20.5) months).ResultsLumasiran treatment was previously reported to reduce spot urinary oxalate:creatinine ratio by 72% at month 6, which was maintained at 72% at month 12; mean month 12 reductions in prespecified weight subgroups were 89%, 68%, and 71% for patients weighing < 10 kg, 10 to < 20 kg, and ≥ 20 kg, respectively. The mean reduction from baseline in plasma oxalate level was reported to be 32% at month 6, and this improved to 47% at month 12. Additional improvements were also seen in nephrocalcinosis grade, and kidney stone event rates remained low. The most common lumasiran-related adverse events were mild, transient injection-site reactions (3 patients (17%)).ConclusionsLumasiran treatment provided sustained reductions in urinary and plasma oxalate through month 12 across all weight subgroups, with an acceptable safety profile, in infants and young children with PH1.Graphical abstractA higher resolution version of the Graphical abstract is available as Supplementary information

Lumasiran for Advanced Primary Hyperoxaluria Type 1: Phase 3 ILLUMINATE-C Trial

Lumasiran reduces urinary and plasma oxalate (POx) in patients with primary hyperoxaluria type 1 (PH1) and relatively preserved kidney function. ILLUMINATE-C evaluates the efficacy, safety, pharmacokinetics, and pharmacodynamics of lumasiran in patients with PH1 and advanced kidney disease. Phase 3, open-label, single-arm trial. Multinational study; enrolled patients with PH1 of all ages, estimated glomerular filtration rate≤45 mL/min/1.73 m2 (if age≥12 months) or increased serum creatinine level (if age<12 months), and POx≥20 μmol/L at screening, including patients with or without systemic oxalosis. Lumasiran administered subcutaneously; 3 monthly doses followed by monthly or quarterly weight-based dosing. Primary end point: percent change in POx from baseline to month 6 (cohort A; not receiving hemodialysis at enrollment) and percent change in predialysis POx from baseline to month 6 (cohort B; receiving hemodialysis at enrollment). Pharmacodynamic secondary end points: percent change in POx area under the curve between dialysis sessions (cohort B only); absolute change in POx; percent and absolute change in spot urinary oxalate-creatinine ratio; and 24-hour urinary oxalate adjusted for body surface area. All patients (N= 21; 43% female; 76% White) completed the 6-month primary analysis period. Median age at consent was 8 (range, 0-59) years. For the primary end point, least-squares mean reductions in POx were 33.3% (95% CI,-15.2% to 81.8%) in cohort A (n= 6) and 42.4% (95% CI, 34.2%-50.7%) in cohort B (n= 15). Improvements were also observed in all pharmacodynamic secondary end points. Most adverse events were mild or moderate. No patient discontinued treatment or withdrew from the study. The most commonly reported lumasiran-related adverse events were injection-site reactions, all of which were mild and transient. Single-arm study without placebo control. Lumasiran resulted in substantial reductions in POx with acceptable safety in patients with PH1 who have advanced kidney disease, supporting its efficacy and safety in this patient population. Alnylam Pharmaceuticals. Registered at ClinicalTrials.gov with study number NCT04152200 and at EudraCT with study number 2019-001346-17. Primary hyperoxaluria type 1 (PH1) is a rare genetic disease characterized by excessive hepatic oxalate production that frequently causes kidney failure. Lumasiran is an RNA interference therapeutic that is administered subcutaneously for the treatment of PH1. Lumasiran has been shown to reduce oxalate levels in the urine and plasma of patients with PH1 who have relatively preserved kidney function. In the ILLUMINATE-C study, the efficacy and safety of lumasiran were evaluated in patients with PH1 and advanced kidney disease, including a cohort of patients undergoing hemodialysis. During the 6-month primary analysis period, lumasiran resulted in substantial reductions in plasma oxalate with acceptable safety in patients with PH1 complicated by advanced kidney disease.

Primary Hyperoxaluria Type 1: A great masquerader

Primary hyperoxaluria (PH) Types I, II, and III is an autosomal recessive inherited disorder of defect in glyoxylate metabolism due to specific hepatic enzyme deficiencies causing renal damage due to deposition of oxalate crystals that induce renal epithelial cell injury, and inflammation resulting in reduced renal oxalate elimination leading to extra renal deposition of calcium oxalate crystals. PH is under diagnosed because of phenotypic heterogeneity masquerading as infantile nephrocalcinosis (NC) with or without renal failure or renal calculus disease in adults. We present three children with genetically proven PH1 seen over last 2 years along with a brief review of the literature. In this series all cases were female. Two girls had infantile onset of symptoms and one presented in childhood. Renal failure in all with varying sonography features including small size kidneys, multiple renal calculi, bulky kidneys with loss of corticomedullary differentiation were seen. Extrarenal affection was seen in one child. Renal replacement therapy was provided in all. Awareness of PH and early diagnosis by measurement of plasma and urinary oxalate and molecular characterization helps in prompt aggressive therapy, preventing extrarenal manifestations and plan long term management.

Improving Treatment Options for Primary Hyperoxaluria.

The primary hyperoxalurias are three rare inborn errors of the glyoxylate metabolism in the liver, which lead to massively increased endogenous oxalate production, thus elevating urinary oxalate excretion and, based on that, recurrent urolithiasis and/or progressive nephrocalcinosis. Frequently, especially in type 1 primary hyperoxaluria, early end-stage renal failure occurs. Treatment possibilities are scare, namely, hyperhydration and alkaline citrate medication. In type 1 primary hyperoxaluria, vitamin B6, though, is helpful in patients with specific missense or mistargeting mutations. In those vitamin B6 responsive, urinary oxalate excretion and concomitantly urinary glycolate is significantly decreased, or even normalized. In patients non-responsive to vitamin B6, RNA interference medication is now available. Lumasiran® is already available on prescription and targets the messenger RNA of glycolate oxidase, thus blocking the conversion of glycolate into glyoxylate, hence decreasing oxalate, but increasing glycolate production. Nedosiran blocks liver-specific lactate dehydrogenase A and thus the final step of oxalate production. Similar to vitamin B6 treatment, where both RNA interference urinary oxalate excretion can be (near) normalized and plasma oxalate decreases, however, urinary and plasma glycolate increases with lumasiran treatment. Future treatment possibilities are on the horizon, for example, substrate reduction therapy with small molecules or gene editing, induced pluripotent stem cell-derived autologous hepatocyte-like cell transplantation, or gene therapy with newly developed vector technologies. This review provides an overview of current and especially new and future treatment options.Supplementary InformationThe online version contains supplementary material available at 10.1007/s40265-022-01735-x.

Treatment of primary hyperoxaluria type 1.

ABSTRACTSupportive treatment for primary hyperoxaluria type 1 (PH1) focuses on high fluid intake and crystallization inhibitors. A subset of patients with specific PH1 genotypes (c.508G>A and c.454T>A) will respond to pyridoxine, defined as a >30% reduction in urinary oxalate excretion. Response to pyridoxine is variable and in some patients, urinary oxalate may normalize. The first focused treatment for PH1 using an RNA interference agent to reduce urinary oxalate was approved in 2020, and such therapies may significantly alter treatment approaches and long-term outcomes in PH1. Currently PH1 often presents with kidney function impairment and frequently results in end-stage kidney disease (ESKD). With kidney dysfunction, urinary oxalate clearance decreases and multisystem deposition of oxalate (oxalosis) occurs, commonly in bones, eyes, heart and skin. Once plasma oxalate levels exceed 30 µmol/L, aggressive haemodialysis is indicated to prevent oxalosis, even if the glomerular filtration rate (GFR) remains better than for typical dialysis initiation. Peritoneal dialysis alone does not achieve the needed oxalate clearance. Dialysis is a bridge to future transplantation. Liver transplantation restores hepatic alanine-glyoxylate transaminase enzyme activity, allowing glyoxylate detoxification and preventing further oxalosis. The native liver must be removed as part of this process to avoid ongoing pathologic oxalate production. The timing and type of liver transplantation are dependent on pyridoxine sensitivity, age, weight, residual GFR and evidence of systemic oxalate deposition in extrarenal organs. Liver transplant can be isolated or combined with kidney transplantation in a sequential or simultaneous fashion. Isolated kidney transplantation is generally reserved for pyridoxine-sensitive patients only. Although liver transplantation is curative for PH1 and kidney transplantation treats ESKD, ensuing necessary immunosuppression and potential allograft dysfunction impart significant long-term risks.

EPHex: a phase 3, double-blind, placebo-controlled, randomized study to evaluate long-term efficacy and safety of Oxalobacter formigenes in patients with primary hyperoxaluria

BackgroundPrimary hyperoxalurias (PHs) are rare genetic diseases that increase the endogenous level of oxalate, a waste metabolite excreted predominantly by the kidneys and also the gut. Treatments aim to improve oxalate excretion, or reduce oxalate generation, to prevent kidney function deterioration. Oxalobacter formigenes is an oxalate metabolizing bacterium. This Phase III, double-blind, placebo-controlled randomized trial investigated the effectiveness of orally administered Oxabact™, a lyophilized O. formigenes formulation, at reducing plasma oxalate levels in patients suffering from PH.MethodsSubjects (≥ 2 years of age) with a diagnosis of PH and maintained but suboptimal kidney function (mean estimated glomerular filtration rate at baseline < 90 mL/min/1.73 m2) were eligible to participate. Subjects were randomized to receive Oxabact or placebo twice daily for 52 weeks. Change from baseline in plasma oxalate concentration at Week 52 was the primary study endpoint.ResultsForty-three subjects were screened, 25 were recruited and one was discontinued. At Week 52, O. formigenes was established in the gut of subjects receiving Oxabact. Despite decreasing plasma oxalate level in subjects treated with Oxabact, and stable/increased levels with placebo, there was no significant difference between groups in the primary outcome (Least Squares mean estimate of treatment difference was − 3.80 μmol/L; 95% CI: − 7.83, 0.23; p-value = 0.064). Kidney function remained stable in both treatments.ConclusionsOxabact treatment may have stabilized/reduced plasma oxalate versus a rise with placebo, but the difference over 12 months was not statistically significant (p = 0.06). A subtle effect observed with Oxabact suggests that O. formigenes may aid in preventing kidney stones.Graphical abstractA higher resolution version of the Graphical abstract is available as Supplementary information.