Treatment Of Primary Hyperoxaluria Type Research Articles

Efficient and safe in vivo treatment of primary hyperoxaluria type 1 via LNP-CRISPR-Cas9-mediated disruption of glycolate oxidase

Primary hyperoxaluria type 1 (PH1) is a severe genetic metabolic disorder caused by mutations in the AGXT gene, leading to defects in enzymes crucial for glyoxylate metabolism. PH1 is characterized by severe, potentially life-threatening manifestations due to excessive oxalate accumulation, which leads to calcium oxalate crystal deposits in the kidneys and, ultimately, renal failure and systemic oxalosis. Existing substrate reduction therapies, such as inhibition of liver-specific glycolate oxidase (GO) encoded by HAO1 using siRNA or CRISPR/Cas9 delivered by adeno-associated virus (AAV), either require repeated dosing or have raised safety concerns. To address these limitations, our study employed lipid nanoparticles (LNPs) for CRISPR/Cas9 delivery to rapidly generate a PH1 mouse model and validate the therapeutic efficacy of LNP-CRISPR/Cas9 targeting the Hao1 gene. The LNP-CRISPR/Cas9 system exhibited efficient editing of the Hao1 gene, significantly reducing GO expression and lowering urinary oxalate levels in treated PH1 mice. Notably, these effects persisted for 12 months with no significant off-target effects, liver-induced toxicity, or substantial immune responses, highlighting the approach's safety and specificity. Furthermore, the developed humanized mouse model validated the efficacy of our therapeutic strategy. These findings support LNP-CRISPR/Cas9 targeting HAO1 as a promising and safer alternative for PH1 treatment with a single administration.

FRI-152-YI Gene editing to treat liver metabolic disorders: harnessing paired Cas9-Nickases for efficient and safe treatment of primary hyperoxaluria type 1

FRI-152-YI Gene editing to treat liver metabolic disorders: harnessing paired Cas9-Nickases for efficient and safe treatment of primary hyperoxaluria type 1

Gene editing: a near future for the treatment of genetic kidney diseases

The study by Chen etal. is the first to apply the revolutionary genetic engineering tool, base editing, in a rat model for the treatment of primary hyperoxaluria type 1, a disease that originates in the liver but in which the kidney is the main organ affected. This commentary contextualizes and describes the gene-editing technology applied by the authors, provides an interpretation and opinion of their results, and indicates possible future applications.

Efficient and safe therapeutic use of paired Cas9-nickases for primary hyperoxaluria type 1

The therapeutic use of adeno-associated viral vector (AAV)-mediated gene disruption using CRISPR-Cas9 is limited by potential off-target modifications and the risk of uncontrolled integration of vector genomes into CRISPR-mediated double-strand breaks. To address these concerns, we explored the use of AAV-delivered paired Staphylococcus aureus nickases (D10ASaCas9) to target the Hao1 gene for the treatment of primary hyperoxaluria type 1 (PH1). Our study demonstrated effective Hao1 gene disruption, a significant decrease in glycolate oxidase expression, and a therapeutic effect in PH1 mice. The assessment of undesired genetic modifications through CIRCLE-seq and CAST-Seq analyses revealed neither off-target activity nor chromosomal translocations. Importantly, the use of paired-D10ASaCas9 resulted in a significant reduction in AAV integration at the target site compared to SaCas9 nuclease. In addition, our study highlights the limitations of current analytical tools in characterizing modifications introduced by paired D10ASaCas9, necessitating the development of a custom pipeline for more accurate characterization. These results describe a positive advance towards a safe and effective potential long-term treatment for PH1 patients.

Lumasiran (Oxlumo)


 CADTH reimbursement reviews are comprehensive assessments of the clinical effectiveness and cost-effectiveness, as well as patient and clinician perspectives, of a drug or drug class.
 The assessments inform non-binding recommendations that help guide the reimbursement decisions of Canada's federal, provincial, and territorial governments, with the exception of Quebec.
 This review assesses lumasiran (Oxlumo), 94.5 mg/0.5 mL lumasiran (as lumasiran sodium), subcutaneous injection.
 Indication: For the treatment of primary hyperoxaluria type 1 to lower urinary oxalate levels in pediatric and adult patients.

Lumasiran (Oxlumo)


 CADTH recommends that Oxlumo be reimbursed by public drug plans for the treatment of primary hyperoxaluria type 1 (PH1) to lower urinary oxalate levels in pediatric and adult patients if certain conditions are met.
 Oxlumo should only be covered to treat those with a genetically confirmed diagnosis of PH1 and whose urine oxalate excretion is not normalized with standard of care therapy (including 3 to 6 months of vitamin B6).
 Oxlumo should only be reimbursed if its cost is reduced and it is initially prescribed by a nephrologist or metabolic diseases specialist experienced in the diagnosis and management of PH1.

Progress with RNA Interference for the Treatment of Primary Hyperoxaluria.

Over the last few years, US Food and Drug Administration-approved drugs using RNA interference have come to the market. Many have treated liver-specific diseases utilizing N-acetyl galactosamine conjugation because of its effective delivery and limited off-target effects. The autosomal recessive disorder primary hyperoxaluria, specifically type 1, has benefited from these developments. Primary hyperoxaluria arises from mutations in the enzymes involved in endogenous oxalate synthesis. The severity of disease varies but can result in kidney failure and systemic oxalosis. Until recently, the treatment options were limited and focused primarily on supportive treatments, pyridoxine use in a subset of patients with primary hyperoxaluria type 1, and liver-kidney transplants in those who progressed to kidney failure. Two genes have been targeted with RNA interference; lumasiran targets glycolate oxidase and nedosiran targets lactate dehydrogenase A. Lumasiran was recently approved in the treatment of primary hyperoxaluria type 1 and nedosiran is in the approval process. Unfortunately, despite initial hopes that nedosiran may also be a treatment option for primary hyperoxaluria types 2 and 3, initial data suggest otherwise. The use of RNA interference liver-specific targeting for the treatment of primary hyperoxaluria type 1 will likely transform the natural history of the disease.

Primary hyperoxaluria: the pediatric nephrologist's point of view.

ABSTRACTThe clinical presentation of primary hyperoxaluria in children ranges from mildly symptomatic nephrocalcinosis to very early onset end-stage kidney failure with systemic oxalosis, a devastating complication. We review the various manifestations of pediatric hyperoxaluria, treatment options for children with preserved kidney function and appropriate dialysis regimens. Liver or combined liver/kidney transplantation is currently the only definitive treatment for primary hyperoxaluria type 1, but novel RNA interference treatments offer hope for the future. Finally, we address the medical and ethical dilemmas facing pediatricians treating children with hyperoxaluria.

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.

MO040: Development of BBP-711, a small molecule inhibitor of glycolate oxidase for primary hyperoxaluria type 1 and recurrent kidney stone formers

Abstract BACKGROUND AND AIMS BBP-711 is an investigational small molecule inhibitor of glycolate oxidase (GO), currently in development for the treatment of primary hyperoxaluria type 1 (PH1) and recurrent nephrolithiasis. Selection of BBP-711 as a drug candidate followed structural activity optimization and a pharmacological testing strategy that included functional activity in enzyme assays, target engagement in cellular assays and efficacy studies in a rodent model (Agxt−/− mice) of primary hyperoxaluria type 1. METHOD BBP-711 was developed by iterative synthesis and study of the structure–activity relationship of more than 50 GO inhibitors. Lead molecules including BBP-711 were assessed for functional activity by determining inhibition of the conversion of glycolate to oxalate with purified human, mouse and rat HAOX1 enzymes. The ability of BBP-711 to bind directly to immobilized purified hGO (HAOX1 gene product) was evaluated by surface plasmon resonance. Selectivity of BBP-711 was assessed by determining its inhibition of several physiologically related gene products including that from HAOX2. In vitro efficacy of BBP-711 was tested via inhibition of oxalate production in primary hepatocytes cultured from hyperoxaluric Agxt−/− mice. In vivo efficacy of BBP-711 on urinary oxalate excretion was assessed at various doses given by oral gavage in Agxt −/− mice. Pharmacokinetics of BBP-711 was investigated to assess plasma and liver concentrations associated with efficacy. RESULTS BBP-711 is a potent inhibitor of human, rat and mouse GO (IC50 = 15.4 nM, 22.4 nM and 149 nM, respectively). BBP-711 demonstrated stronger direct binding to hGO1 (KD = 6.31 nM) than to rGO2 (KD = 12.8 nM), indicating its preference for GO1 as a target. BBP-711 specificity was demonstrated with <10% activity against off-target enzymes D-amino acid oxidase, dihydroorotate dehydrogenase and lactate dehydrogenase-A at 10 µM. BBP-711 demonstrated concentration-dependent inhibition of oxalate production by Agxt−/− hepatocytes (IC50 = 24.2 nM at 24 hours, IC50 = 42.9 nM at 48 hours). When orally dosed at 7 mg/kg for 5 days in Agxt−/− mice, BBP-711 produced a maximum reduction of urinary oxalate (60%) as well as maximum inhibition of GO activity (>88%). Higher doses did not result in greater reduction in urinary oxalate. Liver exposures (AUC0-24hr) were higher than plasma exposures at all doses tested. GO engagement by BBP-711 was also assessed in an ex vivo assay. Liver extracts from Agxt−/− and wild-type mice dosed with BBP-711 show a dose-dependent reduction in ex vivo GO activity at 1 and 4-hour post-dose. CONCLUSION Iterative and rational optimization of small molecule GO inhibitors resulted in BBP-711, a potent and specific inhibitor of GO with drug-like properties.

A new era of treatment for primary hyperoxaluria type 1.

A new era of treatment for primary hyperoxaluria type 1.

Lumasiran: First Approval.

Lumasiran (Oxlumo™) is a subcutaneously administered small interfering RNA (siRNA) targeting the mRNA for hydroxyacid oxidase 1 gene (HAO1; encodes glycolate oxidase) and was developed by Alnylam Pharmaceuticals for the treatment of primary hyperoxaluria type 1 (PH1). By silencing the gene encoding glycolate oxidase, lumasiran depletes glycolate oxidase and thereby inhibits the synthesis of oxalate, which is the toxic metabolite that is directly associated with the clinical manifestations of PH1. On 19 November 2020, lumasiran received its first global approval in the EU for the treatment of PH1 in all age groups. On 23 November 2020, lumasiran was approved in the USA for the treatment of adult and paediatric patients with PH1. This article summarizes the milestones in the development of lumasiran leading to this first approval.

Liver Transplant for Primary Hyperoxaluria Type 1: Results of Sequential, Combined Liver and Kidney, and Preemptive Liver Transplant.

Primary hyperoxaluria type 1 is an autosomal recessive disorder that causes overproduction and urinary excretion of oxalate. Liver transplant has been suggested as a treatment for primary hyperoxaluria type 1 since the defective enzyme is expressed in the liver. This study aimed to investigate results of combined liver and kidney, sequential, and preemptive livertransplantin patients with primary hyperoxaluria type 1. In this cohort study, we followed patients with primary hyperoxaluria type 1 who underwent liver transplant at our centerin Shiraz, Iran. Clinical and laboratory data of patients were gathered, and major outcomes, including renal failure after liver transplant, rejection, and mortality were recorded. Survival of patients was analyzed by the Kaplan-Meier method. Our study included 24 patients. There were 16 male (66.6%) and 8 female (33.33%) patients. Thirteen patients were in the pediatric age group (age < 18 y), and 11 patients were adults (age ≥ 18 y). Thirteen patients underwent sequential transplant, 8 patients underwent combined liver and kidney transplant, and 3 patients underwent preemptive transplant. All patients received organs from deceased donors. There were no statistically significant differences in mortality, rejection, and hemodialysis after transplant between those with sequential transplant and those with combined liver and kidney transplant (P > .05). Liver transplant can be considered a treatment for patients with primary hyperoxaluria type 1. Combined liver and kidney transplant and preemptive liver transplant could be proper options for these patients.

Re: CRISPR/Cas9-Mediated Glycolate Oxidase Disruption is an Efficacious and Safe Treatment for Primary Hyperoxaluria Type I.

Re: CRISPR/Cas9-Mediated Glycolate Oxidase Disruption is an Efficacious and Safe Treatment for Primary Hyperoxaluria Type I.

CRISPR/Cas9-mediated glycolate oxidase disruption is an efficacious and safe treatment for primary hyperoxaluria type I

CRISPR/Cas9 technology offers novel approaches for the development of new therapies for many unmet clinical needs, including a significant number of inherited monogenic diseases. However, in vivo correction of disease-causing genes is still inefficient, especially for those diseases without selective advantage for corrected cells. We reasoned that substrate reduction therapies (SRT) targeting non-essential enzymes could provide an attractive alternative. Here we evaluate the therapeutic efficacy of an in vivo CRISPR/Cas9-mediated SRT to treat primary hyperoxaluria type I (PH1), a rare inborn dysfunction in glyoxylate metabolism that results in excessive hepatic oxalate production causing end-stage renal disease. A single systemic administration of an AAV8-CRISPR/Cas9 vector targeting glycolate oxidase, prevents oxalate overproduction and kidney damage, with no signs of toxicity in Agxt1−/− mice. Our results reveal that CRISPR/Cas9-mediated SRT represents a promising therapeutic option for PH1 that can be potentially applied to other metabolic diseases caused by the accumulation of toxic metabolites.

High throughput cell-based assay for identification of glycolate oxidase inhibitors as a potential treatment for Primary Hyperoxaluria Type 1.

Glycolate oxidase (GO) and alanine:glyoxylate aminotransferase (AGT) are both involved in the peroxisomal glyoxylate pathway. Deficiency in AGT function causes the accumulation of intracellular oxalate and the primary hyperoxaluria type 1 (PH1). AGT enhancers or GO inhibitors may restore the abnormal peroxisomal glyoxylate pathway in PH1 patients. With stably transformed cells which mimic the glyoxylate metabolic pathway, we developed an indirect glycolate cytotoxicity assay in a 1,536-well plate format for high throughput screening. This assay can be used to identify compounds that reduce indirect glycolate-induced cytotoxicity by either enhancing AGT activity or inhibiting GO. A pilot screen of 4,096 known compounds identified two membrane permeable GO inhibitors: dichromate salt and colistimethate. We also developed a GO enzyme assay using the hydrogen peroxide-Amplex red reporter system. The IC50 values of potassium dichromate, sodium dichromate, and colistimethate sodium were 0.096, 0.108, and 2.3 μM in the GO enzyme assay, respectively. Further enzyme kinetic study revealed that both types of compounds inhibit GO activity by the mixed linear inhibition. Our results demonstrate that the cell-based assay and GO enzyme assay developed in this study are useful for further screening of large compound libraries for drug development to treat PH1.

SiRNA Therapeutics for Primary Hyperoxaluria: A Beginning

Realization of the early promise of gene therapy has been elusive. Long and eagerly anticipated, particularly for orphan diseases with few available therapeutic alternatives, only within recent years have such treatments begun to reach phase III clinical trials.1 Two articles in this issue of Molecular Therapy identify inhibition of glycolate oxidase as a potential treatment for type 1 primary hyperoxaluria (PH1), an autosomal recessive condition in which excess oxalate produced by the liver causes kidney damage and severe systemic disease. Both teams of investigators demonstrated reduction in oxalate production in a mouse knockout model of the disease through absence or inhibition of glycolate oxidase (GO). Hepatic GO converts glycolate to glyoxylate, which is the primary substrate for production of oxalate. Thus, substrate reduction was achieved. Martin-Higueras and colleagues2 demonstrated that the hyperoxaluria of the AGXT knockout mouse was substantially reduced following double knockout of AGXT and GO. Dutta and colleagues3 approached the problem differently, using Dicer-short interfering RNA (Dicer-siRNA) for inhibition targeting hydroxyacid oxidase 1 (HAO-1) messenger RNA, which encodes GO.3 Using this approach, they were able to demonstrate normalization of oxalate production in hepatocytes of AGXT knockout mice. These observations suggest an innovative approach to treatment for patients with PH1 and impart new hope for patients with PH, their families, and the physicians who care for them. This is especially true in that early experience with other applications of siRNA for treatment of human diseases, including amyloidosis, hypercholesterolemia, and α1-antitrypsin deficiency, has been encouraging.1,4

Development of a phenotypic high-content assay to identify pharmacoperone drugs for the treatment of primary hyperoxaluria type 1 by high-throughput screening.

Primary hyperoxaluria is a severe disease for which the best current therapy is dialysis or organ transplantation. These are risky, inconvenient, and costly procedures. In some patients, pyridoxine treatment can delay the need for these surgical procedures. The underlying cause of particular forms of this disease is the misrouting of a specific enzyme, alanine:glyoxylate aminotransferase (AGT), to the mitochondria instead of the peroxisomes. Pharmacoperones are small molecules that can rescue misfolded proteins and redirect them to their correct location, thereby restoring their function and potentially curing disease. In the present study, we miniaturized a cell-based assay to identify pharmacoperone drugs present in large chemical libraries to selectively correct AGT misrouting. This assay employs AGT-170, a mutant form of AGT that predominantly resides in the mitochondria, which we monitor for its relocation to the peroxisomes through automated image acquisition and analysis. Over the course of a pilot screen of 1,280 test compounds, we achieved an average Z'-factor of 0.72±0.02, demonstrating the suitability of this assay for HTS.

Mutations in HAO1 encoding glycolate oxidase cause isolated glycolic aciduria

BackgroundThe primary hyperoxalurias are a group of recessive kidney diseases, characterised by extensive accumulation of calcium oxalate that progressively coalesces into kidney stones. Oxalate overproduction is facilitated by perturbations in...

Current treatment for primary hyperoxaluria type 1: When should liver/kidney transplantation be considered

Current treatment for primary hyperoxaluria type 1: When should liver/kidney transplantation be considered