Phase 3 trial of lumasiran for primary hyperoxaluria type 1: A new RNAi therapeutic in infants and young children

Open AccessPublished:December 07, 2021DOI:https://doi.org/10.1016/j.gim.2021.10.024

      Abstract

      Purpose

      Primary hyperoxaluria type 1 (PH1) is a rare, progressive, genetic disease with limited treatment options. We report the efficacy and safety of lumasiran, an RNA interference therapeutic, in infants and young children with PH1.

      Methods

      This single-arm, open-label, phase 3 study evaluated lumasiran in patients aged <6 years with PH1 and an estimated glomerular filtration rate >45 mL/min/1.73 m2, if aged ≥12 months, or normal serum creatinine, if aged <12 months. The primary end point was percent change in spot urinary oxalate to creatinine ratio (UOx:Cr) from baseline to month 6. Secondary end points included proportion of patients with urinary oxalate ≤1.5× upper limit of normal and change in plasma oxalate.

      Results

      All patients (N = 18) completed the 6-month primary analysis period. Median age at consent was 50.1 months. Least-squares mean percent reduction in spot UOx:Cr was 72.0%. At month 6, 50% of patients (9/18) achieved spot UOx:Cr ≤1.5× upper limit of normal. Least-squares mean percent reduction in plasma oxalate was 31.7%. The most common treatment-related adverse events were transient, mild, injection-site reactions.

      Conclusion

      Lumasiran showed rapid, sustained reduction in spot UOx:Cr and plasma oxalate and acceptable safety in patients aged <6 years with PH1, establishing RNA interference therapies as safe, effective treatment options for infants and young children.

      Graphical abstract

      Keywords

      Introduction

      Primary hyperoxaluria type 1 (PH1) is a rare, progressive, autosomal recessive genetic disease characterized by increased hepatic oxalate production caused by a deficiency of the liver peroxisomal enzyme alanine-glyoxylate aminotransferase, encoded by AGXT. In individuals with reduced alanine-glyoxylate aminotransferase activity, glyoxylate is not efficiently converted into glycine but instead undergoes oxidation to oxalate in the liver (Supplemental Figure 1A and B), leading to excessive oxalate delivery to the kidneys for excretion. Excess oxalate combines with calcium to form crystals, resulting in nephrocalcinosis and nephrolithiasis, leading to progressive kidney disease and ultimately kidney failure in many patients. As kidney function declines, the elimination of oxalate is reduced, leading to elevated plasma oxalate concentration and calcium oxalate deposition in tissues, including bone, vasculature, heart, skin, eyes, and nerves, resulting in severe end-organ damage, a condition termed systemic oxalosis.
      • Sas D.J.
      • Harris P.C.
      • Milliner D.S.
      Recent advances in the identification and management of inherited hyperoxalurias.
      Although PH1 can manifest at any age, kidney failure, systemic oxalosis, and increased mortality often affect children,
      • Hopp K.
      • Cogal A.G.
      • Bergstralh E.J.
      • et al.
      Phenotype-genotype correlations and estimated carrier frequencies of primary hyperoxaluria.
      • Harambat J.
      • Fargue S.
      • Acquaviva C.
      • et al.
      Genotype-phenotype correlation in primary hyperoxaluria type 1: the p.Gly170Arg AGXT mutation is associated with a better outcome.
      • Mandrile G.
      • van Woerden C.S.
      • Berchialla P.
      • et al.
      Data from a large European study indicate that the outcome of primary hyperoxaluria type 1 correlates with the AGXT mutation type.
      • Danpure C.J.
      Primary hyperoxaluria.
      with infants often having the most severe disease course.
      • Harambat J.
      • Fargue S.
      • Acquaviva C.
      • et al.
      Genotype-phenotype correlation in primary hyperoxaluria type 1: the p.Gly170Arg AGXT mutation is associated with a better outcome.
      ,
      • Jellouli M.
      • Ferjani M.
      • Abidi K.
      • et al.
      Primary hyperoxaluria in infants.
      Treatment options for PH1 have been limited to hyperhydration and crystallization inhibitors, as well as pyridoxine for a specific subset of patients with PH1, all with varying degrees of efficacy and tolerability. Despite these interventions, many patients continue to experience serious and life-threatening manifestations of this disease. Liver transplantation corrects the metabolic overproduction of oxalate in patients with PH1 but is associated with significant risks and morbidities, including lifelong immunosuppression.
      • Cochat P.
      • Rumsby G.
      Primary hyperoxaluria.
      RNA interference (RNAi) is a naturally occurring mechanism for regulating gene expression. Small interfering RNAs (siRNAs), mediators of this process, are an innovative class of medicines with indications for both rare disorders and common conditions.
      • Weng Y.
      • Xiao H.
      • Zhang J.
      • Liang X.J.
      • Huang Y.
      RNAi therapeutic and its innovative biotechnological evolution.
      ,
      • Setten R.L.
      • Rossi J.J.
      • Han S.P.
      The current state and future directions of RNAi-based therapeutics.
      Although RNAi therapies have potential application across a wide range of human disease, no clinical trials of RNAi have been previously reported in infants and young pediatric patients.
      Lumasiran is a subcutaneously administered, liver-directed RNAi therapeutic targeting the messenger RNA of glycolate oxidase (GO), encoded by HAO1. GO catalyzes the oxidation of glycolate to glyoxylate. By blocking GO production, lumasiran reduces the amount of glyoxylate substrate available for oxalate production (Supplemental Figure 1C). Hence, lumasiran is designed to significantly reduce hepatic oxalate overproduction, the primary cause of morbidity and mortality in PH1.
      We present results from the 6-month primary analysis period of ILLUMINATE-B, a phase 3 trial designed to evaluate the efficacy of lumasiran as measured by changes in spot urinary oxalate (UOx) to creatinine ratio (UOx:Cr) in patients aged <6 years with PH1 and an estimated glomerular filtration rate (eGFR) >45 mL/min/1.73 m2.

      Materials and Methods

       Study design and patients

      ILLUMINATE-B is a multicenter, multinational, single-arm, open-label, phase 3 study of lumasiran in patients aged <6 years with PH1 (ClinicalTrials.gov: NCT03905694; EudraCT: 2018-004014-17). Results from the 6-month primary analysis period are presented. The 54-month long-term extension period is ongoing.
      Eligibility required full-term infants to children aged <6 years at consent with a genetically confirmed diagnosis of PH1 and UOx:Cr greater than the upper limit of normal (ULN) for age for ≥2 of 3 samples during screening. Eligible patients had eGFR >45 mL/min/1.73 m2 based on the Schwartz Bedside Formula
      • Schwartz G.J.
      • Muñoz A.
      • Schneider M.F.
      • et al.
      New equations to estimate GFR in children with CKD.
      if aged ≥12 months or normal serum creatinine if aged <12 months without clinical evidence of extrarenal systemic oxalosis. Patients on therapeutic pyridoxine (vitamin B6) were required to have been on a stable regimen for ≥90 days before screening. All patients continued standard-of-care therapies, including hyperhydration, crystallization inhibitors, and/or pyridoxine therapy, through the 6-month primary analysis period.
      Lumasiran was administered subcutaneously in 3 weight-based regimens. Children who weighed <10 kg received 6 mg/kg monthly thrice followed by 3 mg/kg monthly, children who weigh 10 to <20 kg received 6 mg/kg monthly thrice followed by 6 mg/kg quarterly, and children who weighed >20 kg received 3 mg/kg monthly thrice followed by 3 mg/kg quarterly (Supplemental Table 1). The dosing regimen was selected to achieve similar liver concentrations and target suppression in all weight groups. Considering the rapid growth rate, higher relative liver size, and faster drug clearance based on allometric principles,
      • Anderson B.J.
      • Holford N.H.
      Mechanism-based concepts of size and maturity in pharmacokinetics.
      children who weigh <20 kg require a higher dose to achieve similar liver concentration and target suppression as children who weigh >20 kg, and children who weigh <10 kg require more frequent ongoing dosing (monthly) to keep up with rapid pace of growth.
      Patients underwent efficacy and safety assessments at least monthly, with additional pharmacokinetic and pharmacodynamic assessments at prespecified visits. Study visits and drug administration were scheduled on the basis of 28-day months.

       End points

      The primary outcome, percent change in UOx from baseline to month 6, was assessed with UOx:Cr levels from random spot urine collections. Spot urine samples were used owing to the inability of young children to comply with 24-hour urine collections. Spot UOx:Cr levels correlate with 24-hour UOx levels and provide an alternative to 24-hour UOx levels.
      • Hong Y.H.
      • Dublin N.
      • Razack A.H.
      • Mohd M.A.
      • Husain R.
      Twenty-four hour and spot urine metabolic evaluations: correlations versus agreements.
      • Clifford-Mobley O.
      • Tims C.
      • Rumsby G.
      The comparability of oxalate excretion and oxalate:creatinine ratio in the investigation of primary hyperoxaluria: review of data from a referral centre.
      • Reusz G.S.
      • Dobos M.
      • Byrd D.
      • Sallay P.
      • Miltényi M.
      • Tulassay T.
      Urinary calcium and oxalate excretion in children.
      For all patients, triplicate single-void samples were collected within 7 days before dosing, and the mean values of these triplicate samples were used as the baseline and postdose values in the analysis to account for the variability of the measure. Secondary end points for the primary analysis period included change in additional measures of UOx excretion, plasma oxalate levels, plasma pharmacokinetic parameters, and eGFR. Select exploratory end points included change in kidney stone events, nephrocalcinosis, plasma glycolate, and occurrence of antidrug antibodies (ADAs). Safety assessments included monitoring of adverse events (AEs) and laboratory assessments.
      Oxalate and glycolate assessments were evaluated by validated liquid chromatography–tandem mass spectrometry assays at a central laboratory. Medullary nephrocalcinosis was graded per kidney on a scale of 0 to 3 using ultrasonography, where 0 indicates the absence of nephrocalcinosis and a higher grade indicates greater severity.
      • Dick P.T.
      • Shuckett B.M.
      • Tang B.
      • Daneman A.
      • Kooh S.W.
      Observer reliability in grading nephrocalcinosis on ultrasound examinations in children.
      Kidney ultrasounds were graded centrally by a single radiologist blinded to oxalate levels and timepoint. Changes in the grade of nephrocalcinosis were grouped into 4 categories of overall change, accounting for both kidneys: no change, improving, worsening, and indeterminate (1 kidney improving and 1 worsening).
      Kidney stone events included at least 1 of the following: visit to a health care provider because of a kidney stone, medication for renal colic, stone passage, or macroscopic hematuria caused by a kidney stone. Events were adjudicated by the investigator.

       Statistical analysis

      A planned sample size of 20 patients was determined on the basis of feasibility considerations. Efficacy analyses were performed in all patients who received lumasiran and had at least 1 valid spot UOx:Cr value both at baseline and months 3 to 6. Safety was assessed in all patients who received lumasiran, and pharmacokinetic parameters were evaluated in patients with at least 1 evaluable postdose blood sample.
      The primary analysis of percent change in spot UOx:Cr was based on a mixed-effect model for repeated measures with the estimate calculated as the least-squares (LS) mean of the primary outcome variable averaged across months 3 to 6. Given the known age-related decline in UOx in infants and young children,
      • Milliner D.S.
      • Harris P.C.
      • Cogal A.G.
      • Lieske J.C.
      Primary hyperoxaluria type 1.
      sensitivity analysis of the percent change in the ratio of spot UOx:Cr to age-dependent ULN, as reported in literature,
      • Matos V.
      • Van Melle G.
      • Werner D.
      • Bardy D.
      • Guignard J.P.
      Urinary oxalate and urate to creatinine ratios in a healthy pediatric population.
      was performed to confirm the robustness of the primary end point result. Subgroup analyses by weight-based dosing groups were performed to further understand treatment effect.
      Summary statistics (mean or LS mean) with 2-sided 95% CIs for the primary and secondary end points are provided. Statistical analyses were performed using SAS version 9.4 or later (SAS Institute).

      Results

      From April 22, 2019 through June 30, 2020, 18 patients across 9 sites in 5 countries completed the 6-month primary analysis period with a median treatment duration of 5.6 calendar months (range, 5.3-5.8 months). Patients received 4 or 6 doses depending on weight (Supplemental Table 1), with a cumulative total of 76 doses and no missed doses. Approximately half of the patients were female (10 [56%]), and most patients were White (16 [89%]). Age at consent ranged from 3 to 72 months (Table 1, Supplemental Table 2), and body weight at first dose ranged from 6.2 to 24.3 kg.
      Table 1Baseline demographic and clinical characteristics of the patients
      Characteristic<10 kg, n = 310 to <20 kg, n = 12≥20 kg, n = 3All Treated, N = 18
      Age at consent, mo, median (range)10.1 (3-14)50.1 (23-72)62.2 (54-72)50.1 (3-72)
      Age at diagnosis, mo, median0.822.727.016.3
      Time from diagnosis to first dose date, mo, median11.628.646.423.5
      Female sex, n (%)1 (33)9 (75)010 (56)
      Race, n (%)
       White1 (33)12 (100)3 (100)16 (89)
       Other2 (67)002 (11)
      Geographic region, n (%)
       Europe2 (67)5 (42)1 (33)8 (44)
       North America002 (67)2 (11)
       Middle East1 (33)7 (58)08 (44)
      Genotype, n (%)
       PR/*
      Any genotype of PR, M, or N. PR was defined as NM_000030.3(AGXT):c.508G>A (p.Gly170Arg) or NM_000030.3(AGXT):c.454T>A (p.Phe152Ile). M and N were defined based on a publication by Mandrile et al.4
      03 (25)03 (17)
       M/M or M/N1 (33)8 (67)1 (33)10 (56)
       N/N2 (67)1 (8)2 (67)5 (28)
      Pyridoxine use, n (%)2 (67)7 (58)2 (67)11 (61)
      Spot urinary oxalate to creatinine ratio, mmol/mmol, median (range)
      1 mmol/mmol = 0.796 mg/mg.
      1.253 (1.126-1.708)0.453 (0.166-1.205)0.350 (0.255-0.693)0.469 (0.166-1.708)
      Plasma oxalate, μmol/L, median (range)
      Upper limit of normal = 12.11 μmol/L (1.09 mg/mL) for plasma oxalate, as determined based on data from healthy adults.
      22.3 (17.2-30.6)9.6 (6.6-19.9)11.7 (7.2-18.7)11.5 (6.6-30.6)
      eGFR, mL/min/1.73 m2, median (range)
      Total n = 16; eGFR calculated only in patients ≥12 months of age.
      135
      eGFR (mL/min/1.73 m2) was calculated from serum creatinine on the basis of the Schwartz Bedside Formula10 for patients aged ≥12 months at the time of assessment.
      (135-135)
      111 (76-174)90 (65-135)111 (65-174)
      History of kidney stone events in past 12 mo, n (%)02 (17)1 (33)3 (17)
      Presence of nephrocalcinosis at baseline, n (%)3 (100)10 (83)1 (33)14 (78)
      eGFR, estimated glomerular filtration rate; M, missense; N, nonsense; PR, pyridoxine-responsive.
      a Any genotype of PR, M, or N. PR was defined as NM_000030.3(AGXT):c.508G>A (p.Gly170Arg) or NM_000030.3(AGXT):c.454T>A (p.Phe152Ile). M and N were defined based on a publication by Mandrile et al.
      • Mandrile G.
      • van Woerden C.S.
      • Berchialla P.
      • et al.
      Data from a large European study indicate that the outcome of primary hyperoxaluria type 1 correlates with the AGXT mutation type.
      b 1 mmol/mmol = 0.796 mg/mg.
      c Upper limit of normal = 12.11 μmol/L (1.09 mg/mL) for plasma oxalate, as determined based on data from healthy adults.
      d Total n = 16; eGFR calculated only in patients ≥12 months of age.
      e eGFR (mL/min/1.73 m2) was calculated from serum creatinine on the basis of the Schwartz Bedside Formula
      • Schwartz G.J.
      • Muñoz A.
      • Schneider M.F.
      • et al.
      New equations to estimate GFR in children with CKD.
      for patients aged ≥12 months at the time of assessment.
      Baseline disease characteristics varied with patient weight and age (Table 1, Supplemental Table 2). Baseline spot UOx:Cr, plasma oxalate, and plasma glycolate were highest in patients who weighed <10 kg (n = 3). Spot UOx:Cr levels were a median 5.6× age-dependent ULN
      • Matos V.
      • Van Melle G.
      • Werner D.
      • Bardy D.
      • Guignard J.P.
      Urinary oxalate and urate to creatinine ratios in a healthy pediatric population.
      (range, 2.4-15.1). Kidney stone events were reported by 3 (17%) patients during the 12 months before informed consent was obtained, and 14 (78%) patients had nephrocalcinosis at baseline. The use of pyridoxine was reported by 11 (61%) patients.
      Positive results were shown for the primary end point with a rapid and sustained reduction in spot UOx:Cr from baseline to month 6 (averaged months 3-6; LS mean reduction, 72.0%; 95% CI, 66.4%-77.5%) (Table 2, Figure 1, Supplemental Figure 2). The robustness of the primary end point result was confirmed through sensitivity analyses and 24-hour urinary analysis (Table 2, Supplemental Table 3). The LS mean reduction from baseline for the ratio of spot UOx:Cr to ULN averaged from months 3 to 6 was 70.2% (95% CI, 64.8%-75.6%). In a prespecified subgroup analysis by weight category, the mean observed percent reduction from baseline at month 6 in spot UOx:Cr was 84% for patients who weighed <10 kg, 69% for those who weighed 10 to <20 kg, and 70% for those who weighed ≥20 kg (Figure 1). All patients showed a substantial reduction in spot UOx:Cr from their baseline levels regardless of age (Figure 2, Supplemental Figure 3).
      Table 2Primary and secondary end points
      End PointParameterLumasiran

      N = 18
      Primary end point
       Percent change in spot urinary oxalate to creatinine ratio from baseline to mo 6 (average of mo 3-6)
      The LS mean with corresponding SEM and 95% CI is derived using a mixed model for repeated measures.
      LS mean (SEM)−72.0 (2.7)
      95% CI−77.5 to −66.4
       Sensitivity: percent change in ratio of spot urinary oxalate to creatinine to age-specific ULN from baseline to mo 6 (average of mo 3-6)
      The LS mean with corresponding SEM and 95% CI is derived using a mixed model for repeated measures.
      LS mean (SEM)−70.2 (2.6)
      95% CI−75.6 to −64.8
      Secondary end points
       Absolute change in spot urinary oxalate to creatinine ratio (mmol/mmol)
      1 mmol/mmol = 0.796 mg/mg.
      from baseline to mo 6 (average of mo 3-6)
      The LS mean with corresponding SEM and 95% CI is derived using a mixed model for repeated measures.
      LS mean (SEM)−0.49 (0.01)
      95% CI−0.52 to −0.46
       Proportion of patients with spot urinary oxalate to creatinine ratio at mo 6, n (%)≤ULN
      Age-dependent ULN.17
      1 (6)
      ≤1.5× ULN
      Age-dependent ULN.17
      9 (50)
       Percent change in plasma oxalate
      In patients with baseline plasma oxalate ≥ 1.5× lower limit of quantitation (n = 13; mean, 15.6; range, 8.7-30.6 μmol/L at baseline), LS mean reduction from the average of month 3 to month 6 was 39.4% (95% CI, 29.3%-49.4%) or 6.9 μmol/L (95% CI, 5.5-8.3 μmol/L). ULN = 12.11 μmol/L for plasma oxalate, as determined based on data from healthy adults.
      from baseline to mo 6 (average of mo 3-6)
      The LS mean with corresponding SEM and 95% CI is derived using a mixed model for repeated measures.
      LS mean (SEM)−31.7 (3.8)
      95% CI−39.5 to −23.9
       Absolute change in plasma oxalate
      In patients with baseline plasma oxalate ≥ 1.5× lower limit of quantitation (n = 13; mean, 15.6; range, 8.7-30.6 μmol/L at baseline), LS mean reduction from the average of month 3 to month 6 was 39.4% (95% CI, 29.3%-49.4%) or 6.9 μmol/L (95% CI, 5.5-8.3 μmol/L). ULN = 12.11 μmol/L for plasma oxalate, as determined based on data from healthy adults.
      (μmol/L)
      1 μmol/L = 0.09 mg/mL.
      from baseline to mo 6 (average of mo 3‒6)
      The LS mean with corresponding SEM and 95% CI is derived using a mixed model for repeated measures.
      LS mean (SEM)−5.2 (0.5)
      95% CI−6.2 to −4.2
       Change from baseline in eGFR (mL/min/1.73 m2) at mo 6
      Total n = 16; eGFR calculated only in patients aged ≥12 months.
      Mean (SD) change−0.3 (15)
      Mean (SD) % change0.9 (12)
      eGFR, estimated glomerular filtration rate; LS, least-squares; ULN, upper limit of normal.
      a The LS mean with corresponding SEM and 95% CI is derived using a mixed model for repeated measures.
      b 1 mmol/mmol = 0.796 mg/mg.
      c Age-dependent ULN.
      • Matos V.
      • Van Melle G.
      • Werner D.
      • Bardy D.
      • Guignard J.P.
      Urinary oxalate and urate to creatinine ratios in a healthy pediatric population.
      d In patients with baseline plasma oxalate ≥ 1.5× lower limit of quantitation (n = 13; mean, 15.6; range, 8.7-30.6 μmol/L at baseline), LS mean reduction from the average of month 3 to month 6 was 39.4% (95% CI, 29.3%-49.4%) or 6.9 μmol/L (95% CI, 5.5-8.3 μmol/L). ULN = 12.11 μmol/L for plasma oxalate, as determined based on data from healthy adults.
      e 1 μmol/L = 0.09 mg/mL.
      f Total n = 16; eGFR calculated only in patients aged ≥12 months.
      Figure thumbnail gr1
      Figure 1Percent change in spot urinary oxalate to creatinine ratio with lumasiran from BL at each visit, mean (±SEM). BL value was the mean of all assessments collected before the first dose of lumasiran. BL, baseline; M, month.
      Figure thumbnail gr2
      Figure 2Actual values in spot urinary oxalate to creatinine ratio with lumasiran by age. 1 mmol/mmol = 0.796 mg/mg.
      Positive results were also observed for the secondary end points (Table 2). The LS mean of the absolute reduction in spot UOx:Cr from baseline to month 6 (averaged months 3-6) was 0.49 mmol/mmol (95% CI, 0.46-0.52 mmol/mmol). At month 6, 9 of 18 patients achieved near normalization (≤1.5× ULN), including 1 patient who achieved normalization (≤ULN) of spot UOx:Cr. Plasma oxalate reductions were observed in all patients with an LS mean reduction of 31.7% (95% CI, 23.9%-39.5%) or 5.2 μmol/L (95% CI, 4.2-6.2 μmol/L) (Table 2, Supplemental Figure 4). In patients with baseline plasma oxalate ≥1.5× lower limit of quantitation (n = 13), LS mean reduction at month 6 was 39.4% (95% CI, 29.3%-49.4%) or 6.9 μmol/L (95% CI, 5.5-8.3 μmol/L). eGFR, calculated for patients aged ≥12 months, remained stable through month 6 (Table 2, Supplemental Figure 5).
      Lumasiran showed rapid absorption (median time to reach maximum plasma concentration, 3.0-4.2 hours across weight groups) followed by rapid clearance from the systemic circulation with a mean half-life of 1.4 to 8 hours across weight groups. There was a trend of higher weight-normalized clearance with decreasing weight, reflecting the higher relative liver size and faster hepatic uptake in younger children (Supplemental Table 4).
      Exploratory outcomes included change in nephrocalcinosis, kidney stone events, and pharmacodynamic measurements. Of the 14 (78%) patients with baseline nephrocalcinosis (Table 1), 3 had bilateral improvement, 5 had unilateral improvement, and no patients worsened after 6 months of treatment (Supplemental Figure 6). The low rates of kidney stone events were unchanged between the 12-month historical recall and the first 6 months of treatment (Supplemental Table 5). Plasma glycolate initially increased and then plateaued, consistent with a reduction in hepatic GO activity mediated by lumasiran (Supplemental Figure 7).
      Treatment-emergent ADAs were observed in 3 patients. ADAs were transient, of a low titer (1:50), and with no discernible effect on efficacy, safety, or pharmacokinetics.
      All 18 (100%) patients reported at least 1 AE during the primary analysis period (Table 3). No deaths or severe AEs occurred, and no AEs led to treatment discontinuation or interruption or withdrawal from the study. One (6%) patient had a serious AE of viral infection that was moderate in severity and considered unrelated to lumasiran by the investigator. AEs considered related to lumasiran by the investigator were reported in 3 (17%) patients (mild, transient injection-site reactions in 2 patients and headache in 1 patient). No clinically relevant changes in laboratory measures (including hematology, blood chemistries, liver function tests, and kidney parameters), vital signs, physical examinations, or electrocardiograms caused by lumasiran were observed.
      Table 3Safety
      Event, n (%)Number of Patients, n (%)
      <10 kg, n = 310 to <20 kg, n = 12≥20 kg, n = 3All Treated, N = 18
      Adverse events3 (100)12 (100)3 (100)18 (100)
      Adverse events occurring in ≥3 patients overall
       Pyrexia1 (33)4 (33)1 (33)6 (33)
       Rhinitis1 (33)3 (25)04 (22)
       Upper respiratory tract infection02 (17)1 (33)3 (17)
       Vomiting1 (33)2 (17)03 (17)
      Adverse events leading to discontinuation of study treatment0000
      Adverse events leading to withdrawal from the trial0000
      Death0000
      Serious adverse events001 (33)1 (6)
      Severe adverse events0000

      Discussion

      The discovery of RNAi less than 3 decades ago has led to a new therapeutic modality. Because siRNAs can reduce expression of a single gene, RNAi-based therapeutic approaches have enormous potential in a wide variety of diseases and conditions, many of which have limited or suboptimal treatments available. Many of these diseases, including single-gene disorders, cancers, and infectious diseases, affect infants and children.
      • Zhaori G.
      RNAi technique, how far is it from pediatrics?.
      Although RNAi therapies have previously demonstrated efficacy and safety in adults, they have not been evaluated in infants and young children. This ILLUMINATE-B phase 3 multicenter study evaluates the use of an siRNA in infants and young children <6 years old. The results establish a precedent for the use of liver-targeted siRNA therapeutics in infants and young children.
      PH1 is a rare, progressive, genetic disease characterized by oxalate overproduction with life-threatening clinical manifestations. Even in young children, serious manifestations of the disease often include kidney failure, systemic oxalosis, and increased mortality. Treatment options for patients with PH1 have been limited, with many patients with advanced disease requiring liver and kidney transplantation. Elevated UOx concentration leading to increased calcium oxalate crystal supersaturation is the causal factor of kidney stones, nephrocalcinosis, and progressive decline of kidney function in these patients.
      • Zhao F.
      • Bergstralh E.J.
      • Mehta R.A.
      • et al.
      Predictors of incident ESRD among patients with primary hyperoxaluria presenting prior to kidney failure.
      A reduction of UOx excretion (and plasma oxalate levels) achieved by pre-emptive liver-only transplant has been shown to stabilize kidney function and has been associated with an improvement of nephrocalcinosis, highlighting the importance of reducing oxalate production.
      • Galanti M.
      • Contreras A.
      Excellent renal function and reversal of nephrocalcinosis 8 years after isolated liver transplantation in an infant with primary hyperoxaluria type 1.
      ,
      • Perera M.T.
      • Sharif K.
      • Lloyd C.
      • et al.
      Pre-emptive liver transplantation for primary hyperoxaluria (PH-I) arrests long-term renal function deterioration.
      Furthermore, in a limited number of patients homozygous for the pyridoxine-responsive pathogenic variant G170R, a reduction of UOx with pyridoxine treatment has been associated with stabilization or improvement in kidney function and even recovery from dialysis.
      • Lorenz E.C.
      • Lieske J.C.
      • Seide B.M.
      • et al.
      Sustained pyridoxine response in primary hyperoxaluria type 1 recipients of kidney alone transplant.
      ,
      • Lorenz E.C.
      • Lieske J.C.
      • Seide B.M.
      • Olson J.B.
      • Mehta R.
      • Milliner D.S.
      Recovery from dialysis in patients with primary hyperoxaluria type 1 treated with pyridoxine: a report of 3 cases.
      On the basis of the causal role of UOx in kidney stones, nephrocalcinosis, and kidney failure, a substantial reduction in UOx levels is expected to confer clinical benefit and was endorsed as the basis for drug approval for the treatment of PH1 in patients with chronic kidney disease stage 1 to 3a.
      • Milliner D.S.
      • McGregor T.L.
      • Thompson A.
      • et al.
      End points for clinical trials in primary hyperoxaluria.
      In ILLUMINATE-B, lumasiran resulted in rapid and sustained reductions in UOx levels over the first 6 months of therapy with acceptable safety. The reduction in spot UOx:Cr, the primary end point, was substantial (72.0% LS mean reduction from baseline to month 6) with robustness confirmed through a sensitivity analysis. The comparable reduction when UOx:Cr is normalized to the age-related decline observed in infants and young children indicates that lumasiran was responsible for nearly all of the reduction.
      The magnitude of oxalate reduction reported here in infants and children aged <6 years is consistent with that previously reported for children aged ≥6 years and adults in ILLUMINATE-A (24-hour UOx LS mean reductions from baseline to month 6 of 65.4% in lumasiran-treated patients and 11.8% in placebo-treated patients; spot UOx:Cr reductions of 60.5% in lumasiran-treated patients and 8.5% in placebo-treated patients).
      • Garrelfs S.F.
      • Frishberg Y.
      • Hulton S.A.
      • et al.
      Lumasiran, an RNAi therapeutic for primary hyperoxaluria type 1.
      Reductions in plasma oxalate were also similar between the 2 studies, with 39.4% in ILLUMINATE-B and 39.8% in lumasiran-treated patients in ILLUMINATE-A. Reductions in plasma oxalate may have been limited by the fact that median baseline levels were near the ULN (12.11 μmol/L), and reductions below the limit of quantitation (5.55 μmol/L) were conservatively imputed as 5.55 μmol/L. eGFR remained stable throughout the 6 months of lumasiran treatment in both studies. In ILLUMINATE-B, of the 14 patients who had nephrocalcinosis at baseline, 8 (57%) patients showed improvement at month 6, whereas no patients showed worsening or new onset. In ILLUMINATE-A, of the 17 lumasiran-treated patients who had nephrocalcinosis at baseline, 3 (18%) patients showed improvement at month 6, whereas in the placebo group, no patients improved and 1 worsened. Because nephrocalcinosis is an important predictor of long-term kidney outcomes,
      • Tang X.
      • Bergstralh E.J.
      • Mehta R.A.
      • Vrtiska T.J.
      • Milliner D.S.
      • Lieske J.C.
      Nephrocalcinosis is a risk factor for kidney failure in primary hyperoxaluria.
      the results observed at month 6 in both trials are encouraging. Data on the effect of lumasiran on nephrocalcinosis, kidney function, and kidney stone events will continue to be collected.
      Plasma glycolate initially increased and then plateaued, consistent with a reduction in hepatic GO activity. There are no known metabolic consequences of elevated concentrations of glycolate in blood or urine.
      • Frishberg Y.
      • Deschênes G.
      • Groothoff J.W.
      • et al.
      Phase 1/2 study of lumasiran for treatment of primary hyperoxaluria type 1: a placebo-controlled randomized clinical trial.
      Elevated plasma and urinary glycolate concentrations without apparent adverse clinical consequences have been reported in case reports of patients with GO deficiency.
      • Frishberg Y.
      • Zeharia A.
      • Lyakhovetsky R.
      • Bargal R.
      • Belostotsky R.
      Mutations in HAO1 encoding glycolate oxidase cause isolated glycolic aciduria.
      • McGregor T.L.
      • Hunt K.A.
      • Yee E.
      • et al.
      Characterising a healthy adult with a rare HAO1 knockout to support a therapeutic strategy for primary hyperoxaluria.
      • Clifford-Mobley O.
      • Rumsby G.
      • Kanodia S.
      • Didi M.
      • Holt R.
      • Senniappan S.
      Glycolate oxidase deficiency in a patient with congenital hyperinsulinism and unexplained hyperoxaluria.
      • Craigen W.J.
      Persistent glycolic aciduria in a healthy child with normal alanine-glyoxylate aminotransferase activity.
      Plasma pharmacokinetic parameters were generally similar across dosing weight groups. The consistency of the efficacy and pharmacokinetics confirms that the selected dosing regimens based on allometric modeling principles are appropriate for patients with PH1 from birth to adults.
      Lumasiran showed safety in infants and young children in ILLUMINATE-B comparable to the safety in older children and adults previously reported in ILLUMINATE-A. Only mild and moderate AEs were reported, and no patients discontinued treatment or withdrew from the study. Injection-site reactions were mild and transient.
      This study showed that lumasiran is an effective and safe treatment for very young patients with PH1. The results of this study provide evidence that RNAi-based drugs can be used effectively and safely in infants and young children.

       Limitations

      The limitations of this study include the single-arm study design, exclusion of patients with PH1 with more advanced kidney disease, and the short duration of the primary analysis period. The lack of placebo control in this single-arm study was considered appropriate because of the limited number of diagnosed patients aged <6 years. The results of this single-arm study can be contextualized with the results of the placebo-controlled ILLUMINATE-A study. Although random spot UOx:Cr was required for a cohort of young children incontinent of urine in lieu of 24-hour urine collection, our work
      • Garrelfs S.F.
      • Frishberg Y.
      • Hulton S.A.
      • et al.
      Lumasiran, an RNAi therapeutic for primary hyperoxaluria type 1.
      and that of others
      • Hong Y.H.
      • Dublin N.
      • Razack A.H.
      • Mohd M.A.
      • Husain R.
      Twenty-four hour and spot urine metabolic evaluations: correlations versus agreements.
      • Clifford-Mobley O.
      • Tims C.
      • Rumsby G.
      The comparability of oxalate excretion and oxalate:creatinine ratio in the investigation of primary hyperoxaluria: review of data from a referral centre.
      • Reusz G.S.
      • Dobos M.
      • Byrd D.
      • Sallay P.
      • Miltényi M.
      • Tulassay T.
      Urinary calcium and oxalate excretion in children.
      suggest a concordance between the 2 methods. The short duration will be addressed in the 54-month extension period of this study, whereas patients with PH1 with advanced kidney impairment are being assessed in the ongoing ILLUMINATE-C study (NCT04152200).
      In conclusion, lumasiran resulted in rapid and sustained reductions in UOx and plasma oxalate levels across all weight ranges in infants and young children aged <6 years with an acceptable safety profile. The findings in this young population were consistent with those previously observed in children aged ≥6 years and adults. Lumasiran meets a substantial unmet medical need for patients with PH1 and shows that RNAi therapies can be safe and effective in infants and young children.

      Data Availability

      De-identified individual participant data that support these results will be made available in a secure-access environment 12 months after study completion and when the product and indication have been approved for no less than 12 months in the United States and the European Union. Access will be provided contingent on the approval of a research proposal and the execution of a data sharing agreement. Requests for access to data can be submitted via the website www.vivli.org.

      Conflict of Interest

      David J. Sas reports grants and other support from Alnylam Pharmaceuticals and personal fees from Advicenne. Daniella Magen reports research funding, consultancy fees, and nonfinancial support from Alnylam Pharmaceuticals. Wesley Hayes reports travel and accommodation expenses from Alnylam Pharmaceuticals to attend an international investigators’ meeting. Hadas Shasha-Lavsky reports serving as a principal investigator for Alnylam Pharmaceuticals and receiving travel and accommodation expenses from Alnylam Pharmaceuticals to attend international investigators’ meetings. Mini Michael reports serving as a principal investigator for and receiving travel and accommodation expenses from Alnylam Pharmaceuticals to attend international investigators’ meetings. Anne-Laure Sellier-Leclerc reports consultancy fees from Alnylam Pharmaceuticals and Dicerna Pharmaceuticals and was principal investigator for research funded by OxThera. Ali Seddighzadeh reports previous employment by and shareholder of Alnylam Pharmaceuticals (currently employed by Apellis Pharmaceuticals). Jiandong Lu, Bahru Habtemariam, Tracy L. McGregor, and Kenji P. Fujita report previous employment by and shareholder of Alnylam Pharmaceuticals. Yaacov Frishberg reports consultancy fees from Alnylam Pharmaceuticals and membership in the safety review committee. All other authors declare no conflicts of interest.

      Acknowledgments

      Part of the data reported in the manuscript were presented as an ePoster at the American Society of Nephrology Annual Meeting, October 2020, virtual. The study protocol and the statistical analysis plan were developed by the sponsor, Alnylam Pharmaceuticals. Data were collected by trial investigators and were analyzed by the sponsor. Medical writing and editorial assistance were provided by Lisa Tran, MS, and Ana Camejo, PhD, both from Alnylam Pharmaceuticals, and Jinling Wu, MD, PhD, Peloton Advantage, LLC, an OPEN Health company, and funded by Alnylam Pharmaceuticals. This study was funded by Alnylam Pharmaceuticals.
      Clinical trial registry name and registration number were as follows: ILLUMINATE-B; Clinicaltrials.gov: NCT03905694; EudraCT: 2018-004014-17.

      Author Information

      All authors had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
      Conceptualization: D.J.S., D.M., W.H., B.H., T.L.M., Y.F.; Data Curation: J.L., T.L.M., K.P.F.; Methodology: D.J.S., W.H., J.L., B.H., T.L.M., Y.F.; Formal Analysis: J.L., B.H., T.L.M.; Investigation: D.J.S., D.M., W.H., H.S.-L., M.M., I.S., A.-L.S.-L., A.S., T.L.M., Y. F.; Software: J.L.; Validation: J.L.; Writing - original draft/Data interpretation: J.L., B.H., T.L.M.
      All authors contributed to revision of the final version of the manuscript, approved the final version submitted, and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. D.J.S. acts as guarantor for the work and attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.

      Ethics Declaration

      The study was conducted in accordance with Good Clinical Practice guidelines and the Declaration of Helsinki. An independent data monitoring committee oversees the safety and overall conduct of this study. The study protocol and amendments were reviewed and approved by the Mayo Clinic Institutional Review Board. All other institutions involved in this study received local institutional review board or ethics committee approval before enrollment of the first participant at their institute. Legal guardians provided written informed consent and patients provided assent per local regulations and institutional standards. Data were collected by trial investigators and analyzed by the sponsor.

      Members of the ILLUMINATE-B Workgroup

      Justine Bacchetta, Véronique Baudouin, Rachel Becker-Cohen, Shimrit Tzvi Behr, Efrat Ben-Shalom, Maria Berdaguer, Detlef Bockenhauer, Pierre Cochat, Martin Coenen, Carl H. Cramer, Georges Deschênes, Claire Dossier, Emilie Doye, Liat Feraru Feldman, Maximilian Hohenadel, Florentia Kaguelidou, Irina Libinson Zebegret, John C. Lieske, Anne Maisin, Dawn S. Milliner, Moran Plonsky Toder, Shirley Pollack, Aurélie Portefaix, Bruno Ranchin, Choni Rinat, Adnan Safdar, Gesa Schalk, Poyyapakkam R. Srivaths, Cheryl L. Tran, William Van't Hoff, Jenny Weinbrand-Goichberg, Irith Weissman

      Supplementary Materials

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