www.kidney-international.org clinical trial The long-acting C5 inhibitor, ravulizumab, is effective and safe in pediatric patients with atypical hemolytic uremic syndrome naïve to complement OPEN inhibitor treatment Gema Ariceta1, Bradley P. Dixon2, Seong Heon Kim3, Gaurav Kapur4, Teri Mauch5,6, Stephan Ortiz7, Marc Vallee8, Andrew E. Denker9, Hee Gyung Kang10 and Larry A. Greenbaum11; the 312 Study Group12 1 Paediatric Nephrology Department, University Hospital Vall d’Hebron, Barcelona, Spain; 2Renal Section, Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado, USA; 3Department of Pediatrics, Pusan National University Children’s Hospital, Yangsan, Korea; 4Faculty of Pediatric Sciences, Central Michigan University, Mount Pleasant, Michigan, USA; 5Division of Pediatric Nephrology, University of Nebraska Medical Center, Omaha Children’s Hospital and Medical Center, Omaha, Nebraska, USA; 6 Department of Nephrology and Hypertension, Division of Pediatrics, University of Utah, Salt Lake City, Utah, USA; 7Clinical and Non- Clinical Pharmacology, Alexion Pharmaceuticals Inc., Boston, Massachusetts, USA; 8Biostatistics, Alexion Pharmaceuticals Inc., Boston, Massachusetts, USA; 9Clinical Development, Alexion Pharmaceuticals Inc., Boston, Massachusetts, USA; 10Division of Pediatric Nephrology, Department of Pediatrics, Seoul National University College of Medicine, Seoul, Korea; and 11Division of Pediatric Nephrology, Emory University School of Medicine and Children’s Healthcare of Atlanta, Atlanta, Georgia, USA Ravulizumab, a long-acting complement C5 inhibitor and 213 x109/L through week 26 and week 50, respectively. engineered from eculizumab, allows extending The median increase above baseline in estimated maintenance dosing from every 2–3 weeks to every 4–8 glomerular filtration rate was 80 and 94 mL/min/1.73m2 weeks depending on bodyweight. Here, we evaluated the through week 26 and week 50, respectively. No unexpected efficacy and safety of ravulizumab in complement inhibitor- adverse events, deaths, or meningococcal infections naïve children (under 18 years) with atypical hemolytic occurred. Thus, ravulizumab rapidly improved hematologic uremic syndrome. In this phase III, single-arm trial, and kidney parameters with no unexpected safety concerns ravulizumab was administered every eight weeks in in complement inhibitor-naïve children with atypical patients 20 kg and over, and four weeks in patients under hemolytic uremic syndrome. 20 kg. The primary endpoint was a complete thrombotic Kidney International (2021) 100, 225–237; https://doi.org/10.1016/ microangiopathy response (normalization of platelet count j.kint.2020.10.046 and lactate dehydrogenase, and a 25% or more KEYWORDS: atypical hemolytic uremic syndrome; complement; eculizumab; improvement in serum creatinine) through 26 weeks. hemolytic uremic syndrome; ravulizumab; thrombotic microangiopathy Secondary endpoints included change in hematologic Copyright ª 2020, International Society of Nephrology. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license parameters and kidney function. 18 patients with a median (http://creativecommons.org/licenses/by-nc-nd/4.0/). age of 5.2 years were evaluated. At baseline, symptoms of atypical hemolytic uremic syndrome outside the kidney A were present in 72.2% of patients and 38.9% had been in intensive care. Baseline estimated glomerular filtration rate typical hemolytic uremic syndrome (aHUS) is a rare, was 22 mL/min/1.73 m2. By week 26, 77.8% of patients life-threatening disease associated with complement achieved a complete thrombotic microangiopathy dysregulation, characterized by thrombotic microangi- response; 94.4%, 88.9% and 83.3% of patients achieved opathy (TMA).1,2 Microangiopathic hemolytic anemia, platelet normalization, lactate dehydrogenase thrombocytopenia, and acute kidney injury are hallmarks of normalization and a 25% or more improvement in serum aHUS, but aHUS can also affect organs other than the kid- creatinine, respectively. By week 50, 94.4% patients had neys.1 Without appropriate treatment, aHUS causes signifi- achieved a complete thrombotic microangiopathy cant morbidity and mortality, with 29% of children response. Median improvement in platelet count was 246 requiring dialysis or dying within 1 year and 48% reaching end-stage kidney disease or dying at 3 years, despite plasma therapy.3,4 Correspondence: Gema Ariceta, Paediatric Nephrology Department, Uni- Eculizumab (Alexion Pharmaceuticals Inc., Boston, MA, versity Hospital Vall d’Hebron, 119, 08035 Barcelona, Spain. E-mail: USA) has been approved for the treatment of aHUS since gariceta@vhebron.net 2011.5,6 It has proved highly effective in children with 12 Members of the 312 Study Group are listed in the Appendix. aHUS.7–10 However, eculizumab treatment regimen involves Received 2 July 2020; revised 16 October 2020; accepted 30 October frequent intravenous infusions (every 2 weeks in patients 2020; published online 8 December 2020 weighing >10 kg), which can be particularly burdensome for Kidney International (2021) 100, 225–237 225 clinical trial G Ariceta et al.: Ravulizumab efficacy and safety in pediatric aHUS Figure 1 | Patient disposition. aOne patient was discontinued on day 14 because of laboratory results for platelet count, lactate dehydrogenase (LDH), and hemoglobin not meeting inclusion criteria; one patient was discontinued on day 43 because of positive Shiga toxin- producing Escherichia coli test. bPatient was discontinued on day 7 because of laboratory results for LDH not meeting inclusion criteria (predose local laboratory results for LDH were also exclusionary). cPatient was discontinued on day 21 because of serious adverse events of hypertensive crisis and worsening anemia. dAt last follow-up. aHUS, atypical hemolytic uremic syndrome; TMA, thrombotic microangiopathy. pediatric patients and caregivers. A reduction of dosing fre- adults with aHUS has been demonstrated in a recently pub- quency may improve the quality of life and adherence to lished phase 3 trial report (NCT02949128).17 In this study, we treatment.11–13 assessed the efficacy and safety of ravulizumab in Ravulizumab, a humanized monoclonal antibody, is a complement-inhibitor treatment-naïve children with aHUS long-acting complement C5 inhibitor recently approved for through an initial evaluation period of 26 weeks and an treatment of aHUS in adults and children.14,15 Ravulizumab interim data cut point through the extension period. was engineered through selective modifications to eculizu- mab. These modifications included 2 amino acid sub- RESULTS stitutions made to preserve high binding affinity to C5 at pH Patient characteristics 7.4 in blood, but permitting dissociation of C5 from rav- Twenty-one complement-inhibitor naïve children were ulizumab at pH 6.0. Two additional substitutions were made enrolled, receiving $1 dose of ravulizumab, forming the to increase the affinity for neonatal Fc receptor, with all 4 safety set of this analysis (Figure 1). Two patients were modifications resulting in increased antibody recycling. excluded from the full analysis set because of ineligibility after Overall, these substitutions, while targeting the same C5 treatment (one patient did not meet laboratory criteria for epitope, enhanced the duration of terminal complement in- platelet count, lactate dehydrogenase [LDH], and hemoglo- hibition, leading to a mean half-life >4 times greater than bin; and the other had a positive Shiga toxin-producing eculizumab (approximately 51.8 days) because of additional Escherichia coli test), and one patient was excluded because recycling of binding and neutralization of C5 (Supplementary of a protocol violation (did not meet the laboratory criteria Figure S1).16 As such, ravulizumab offers a reduced dosing for LDH). The full analysis set comprised 18 patients with a frequency (every 4–8 weeks based on body weight) relative to median age of 5.2 (range, 0.5–17.3) years (Table 1). Ten pa- eculizumab. The clinical efficacy and safety of ravulizumab in tients (55.6%) were female, 9 (50.0%) were White, and the 226 Kidney International (2021) 100, 225–237 G Ariceta et al.: Ravulizumab efficacy and safety in pediatric aHUS clinical trial Table 1 | Baseline demographics, disease characteristics, and Table 2 | Complete TMA response at week 26 and week 50 laboratory values (full analysis set) Evaluation Variable Overall (N [ 18) Initial evaluation period through week 50 Variable through week 26 (n ¼ 18) (n ¼ 18) Age at time of first infusion, median (range), yr 5.2 (0.5–17.3) Age at time of first infusion category, yr Complete TMA response 14 (77.8) 17 (94.4) Birth to <2 2 (11.1) Platelet count 17 (94.4) 17 (94.4) 2–<6 9 (50.0) normalization 6–<12 5 (27.8) LDH normalization 16 (88.9) 17 (94.4) 12–<18 2 (11.1) 25% Improvement in 15 (83.3) 17 (94.4) Age at time of first aHUS symptoms, 4.7 (0.8–14.7) serum creatinine from median (range), yr baseline Sex Hematologic 16 (88.9) 17 (94.4) Male 8 (44.4) normalization Female 10 (55.6) LDH, lactate dehydrogenase; TMA, thrombotic microangiopathy. Racea Data shown as number (percentage). American Indian or Alaskan Native 1 (5.6) Asian 5 (27.5) Black or African American 3 (16.7) local genetic analyses; see supplemental information). The White 9 (50.0) Unknown 1 (5.6) median age of first aHUS symptoms was 4.7 (range, 0.8–14.7) Weight at time of first infusion, kg years, and the median age at time of first infusion was 5.2 $5–<10 2 (11.1) (range, 0.5–17.3) years. Comorbidities in patients in this $10–<20 9 (50.0) study are listed in Supplementary Table S3. $20–<30 3 (16.7) $30–<40 3 (16.7) Baseline laboratory values are shown in Table 1. Seventeen $40–<60 0 patients completed the 26-week initial evaluation period and $60 1 (5.6) entered the extension period. One patient discontinued because Pretreatment extrarenal signs or symptoms of aHUS 13 (72.2) of an adverse event (AE) during the initial evaluation period. This Any prior kidney transplantb 1 (5.6) Patients who required ICU level of care 7 (38.9) patient, a 21.6-month-old White female, experienced worsening Time in ICU, mean (SD), d (n ¼ 9) 9.0 (17.7) anemia and hypertensive crisis. She weighed <10 kg and received Patients receiving dialysis 6 (33.3) a loading dose of 300 mg ravulizumab on day 1, and a main- Birth to <6 yr (n ¼ 11) 2 (18.2) tenance dose of 300 mg on day 15. During the loading phase, this 6–<18 yr (n ¼ 7) 4 (57.1) Received PE/PI related to this TMA before first infusion 6 (28.6) patient had a serum C5 level $0.5 mg/ml, suggesting incomplete of drug terminal complement inhibition. Following a protocol-specified Platelet count, median (range), 109/Lc 51.25 (14–125) initial pharmacokinetic (PK)/pharmacodynamic (PD) analysis, LDH, median (range), U/Lc 1963.0 (772–4985) Serum creatinine, median (range), mmol/Lc 133.0 (35–264) the loading dose for this weight category was increased to 600 eGFR, median (range), mL/min per 1.73 m2c 22.0 (10–84) mg, to ensure adequate target serum concentrations of rav- HGB, median (range), g/Lc 74.25 (32–106) ulizumab and corresponding reductions in serum C5. Including aHUS, atypical hemolytic uremic syndrome; eGFR, estimated glomerular filtration the initial evaluation period and extension period, the median rate; HGB, hemoglobin; ICU, intensive care unit; LDH, lactate dehydrogenase; PE, duration of follow-up through the current data cut point was plasma exchange; PI, plasma infusion; TMA, thrombotic microangiopathy. Data shown as number (percentage) unless otherwise stated. 82.6 (range, 3.0–110.6) weeks. Only 1 patient was discontinued a b One patient had 2 races entered (White and American Indian or Alaskan Native). from the extension period. This patient had a complete TMA Transplant related to aHUS, December 2014. c Baseline values may be after PE/PI in some patients. response on day 88 and was discontinued because of physician decision on day 350; the reason for discontinuation was not due to a safety concern. All remaining patients had completed at least median weight was 16.7 (range, 8.4–69.3) kg. Before rav- 351 days of the study at the data cut. ulizumab treatment, 6 (28.6%) patients had received plasma exchange/plasma infusion. Before the start of screening, 7 Primary end point (38.9%) patients had been treated in an intensive care unit, The primary end point of the study was complete TMA for a mean duration of 9.0 (17.7) days. Extrarenal symp- response during the initial evaluation period (Table 2). Dur- toms of aHUS were present in 13 (72.2%) patients at baseline ing the 26-week initial evaluation period, 14 of 18 (77.8%) (Supplementary Table S1). Ten patients were tested using the patients achieved complete TMA response. The median time whole exome sequencing method for genetic variants in to complete TMA response considering all available data was complement genes, and 17 were tested for anti-complement 30 (95% confidence interval, 22.0–88.0) days (Figure 2). factor H (CFH) antibodies. Of those tested with both During the extension period, through week 50, an addi- methods, 9 of 10 (90%) had a pathogenic variant in com- tional 3 patients achieved a complete TMA response (result- plement gene and/or anti-CFH antibody (Supplementary ing complete TMA response in a total of 17/18 [94.4%] Table S2). Pathogenic variants were found in 3 patients patients). Only one patient did not achieve a complete TMA (CFH, MCP, and THBD), and CFH antibodies were found in response, as this patient was discontinued during the initial 7 patients (additional pathogenic variants were identified by evaluation period (day 21), as mentioned previously, and had Kidney International (2021) 100, 225–237 227 clinical trial G Ariceta et al.: Ravulizumab efficacy and safety in pediatric aHUS Figure 2 | Time to complete thrombotic microangiopathy (TMA) response through week 50. Kaplan-Meier graph illustrating time to complete TMA response. BL, baseline; CI, confidence interval. not achieved a response in any of the components of complete (eGFR) of 80.0 (range, 0–222.0) ml/min per 1.73 m2 by week TMA response at that point (because a response in any 26 and 94.0 (range, 10–230) ml/min per 1.73 m2 by week 50 component required confirmation at least 28 days after the (Figure 3d). Of the 6 (28.6%) patients receiving dialysis at initial observation, it was not possible for this patient to have baseline, 5 (83.3%) were off dialysis by week 26 and all 6 responded in any component). (100%) were off dialysis by week 50. None of the 12 patients off dialysis at baseline initiated dialysis during the study. Hematologic end points Improvement in eGFR (change to a less severe eGFR category Overall, platelet normalization and $25% improvement in between baseline and week 26) was seen in 15 patients serum creatinine were achieved by day 8 in 65% and 47% (88.2%), with 2 (11.8%) patients remaining in the same patients, respectively. By day 15, 88% patients had achieved category (Figure 4a). By week 50, all 16 patients with evalu- platelet normalization and 53% achieved $25% improve- able data had improved eGFR category (Figure 4b). ment in serum creatinine. Platelet count normalization was achieved in 17 (94.4%) Quality-of-life end points patients during the 26-week initial evaluation period and Nine patients had evaluable Pediatric Functional Assessment through week 50. The median increase in platelet count from of Chronic Illness Therapy (FACIT)-Fatigue data at baseline, baseline to week 26 was 246.0  109/L (range, 57.5–368.5  week 26, and week 50. All 9 patients (100%) had a clinically 109/L); and to week 50, 213.0  109/L (range, 19.5–471.5  meaningful improvement (at least 3 points)18 in Pediatric 109/L) (Figure 3a). FACIT-Fatigue score at week 26 and week 50 compared with LDH normalization was achieved in 16 (88.9%) patients during baseline (Figure 5). The median increase in Pediatric FACIT- the 26-week initial evaluation period, and in 17 (94.4%) patients Fatigue score was 10.0 (range, 4.0–48.0) and 9.0 (range, 3.0– through week 50. The median decrease in LDH from baseline to 47.0) at week 26 and week 50, respectively. week 26 was 1851.5 U/L (range, –4713 to –513 U/L); and to week 50, 1825.5 U/L (range, –4724 to –579 U/L) (Figure 3b). PK/PD analysis Sixteen (88.9%) patients achieved an increase in hemo- Ravulizumab showed immediate, complete, and sustained globin of $20 g/L from baseline, with a confirmatory result terminal complement C5 inhibition (serum-free C5, <0.5 mg/ through week 26, and 17 patients (94.4%) through week 50. ml; Figure 6), with individual free C5 outliers noted at only 3 The increase in hemoglobin from baseline to week 26 was time points. One outlier (day 15 trough; 0.999 mg/ml) was 46.5 g/L (range, 26.5–86.0 g/L); and by week 50, 51.5 g/L observed in a patient in the #5 to <10 kg group who received (range, –19.0 to 80.0 g/L) (Figure 3c). the original loading dose. Consequently, following pre- specified interim PK/PD analysis, the loading dose for Renal end points enrolled patients #5 to <10 kg was increased from 300 to 600 Renal function substantially improved from baseline, with a mg, with no free C5 outliers observed in #5 to <10 kg pa- median increase in estimated glomerular filtration rate tients receiving the updated loading dose. 228 Kidney International (2021) 100, 225–237 G Ariceta et al.: Ravulizumab efficacy and safety in pediatric aHUS clinical trial Figure 3 | Observed end points over time: platelet count (a), lactate dehydrogenase (b), hemoglobin (c), and estimated glomerular filtration rate (eGFR) (d). Data are shown as mean (error bars, 95% confidence interval). BL, baseline. Kidney International (2021) 100, 225–237 229 clinical trial G Ariceta et al.: Ravulizumab efficacy and safety in pediatric aHUS Safety analyses All 21 patients in the safety analysis experienced AEs (Table 3), with pyrexia, headache, nasopharyngitis, diarrhea, and vomiting occurring most frequently (Table 4). Fourteen patients (66.7%) experienced serious AEs (SAEs), the most frequent of which were viral gastroenteritis and abdominal pain, both occurring in 2 patients each (9.5%; a full list of SAEs is shown in Supplementary Table S4). One patient (4.8%), a 21.6-month-old White female, experienced a grade 3 treatment-emergent AE, listed by the investigator as wors- ening anemia and hypertensive crisis, which resulted in study discontinuation on day 21. This patient was in the lowest weight category (<10 kg) and received a loading dose of 300 mg (as described previously), resulting in predose serum concentration of ravulizumab of 137 mg/ml, which was below the target threshold. Four patients (19.0%) experienced AEs during study drug infusion, and one of these patients expe- rienced nonsevere hypersensitivity to ravulizumab on 3 separate occasions. These cases resolved with study drug dose interruption, diphenhydramine and paracetamol, and slower rate of infusion; and the patients remained in the study. No deaths or meningococcal infections were reported. DISCUSSION This study is the first prospective phase 3 trial evaluating the efficacy and safety of ravulizumab, a long-acting C5 inhibitor with a maintenance dosing interval of 4 to 8 weeks, in pe- diatric patients with aHUS. Weight-based dosing of rav- ulizumab resulted in immediate, complete, and sustained terminal complement C5 inhibition, leading to hematologic remission and improvement of renal function in patients with aHUS. The primary end point was met, with 14 (77.8%) patients achieving complete TMA response by week 26. Complete TMA response is a stringent end point requiring platelet count normalization, LDH normalization, and $25% improvement in serum creatinine, demonstrated simulta- neously at 2 separate assessments at least 28 days apart. Considering all available follow-up, this end point was met in a median time of 30 days. An additional 3 patients, described below, met the primary end point by week 50 (overall, 94.4% of patients had a complete TMA response). Figure 4 | Shift in estimated glomerular filtration rate (eGFR) category for the initial evaluation period (a) and the extension One of these patients had extrarenal symptoms of aHUS and period (full analysis set) (b). Data shown as number (percentage). achieved platelet normalization and serum creatinine eGFR categories are shown in ml/min per 1.73 m2. Green cells response on days 18 and 24, respectively. The LDH criterion represent improvement from baseline to day 183; red cells represent worsening; and white cells represent no change. for response was not met until during the extension period (day 297), which is when the patient formally achieved the complete TMA response. The second patient achieved com- plete TMA response on day 351. This patient achieved he- only then became evaluable for serum creatinine criteria, matologic response during the initial evaluation period which were subsequently met. (platelets normalized on day 8, and LDH normalized on day Hematologic normalization was observed in a higher 24). Serum creatinine level did not improve $25% until day proportion of patients at week 26 than complete TMA 351, although it was stable throughout the initial evaluation response, with 16 (88.9%) patients achieving LDH and period (range, 160–235 mmol/L). The third patient achieved platelet count normalization by week 26; by week 50, 17 platelet normalization on day 71 and LDH normalization on (94.4%) patients had achieved hematologic normalization. day 104. This patient discontinued dialysis on day 193 and Similar to other studies on complement inhibitors for the 230 Kidney International (2021) 100, 225–237 G Ariceta et al.: Ravulizumab efficacy and safety in pediatric aHUS clinical trial Figure 5 | Pediatric Functional Assessment of Chronic Illness Therapy-Fatigue over time. Data shown as mean (error bars, 95% confidence interval). BL, baseline. treatment of aHUS,19,20 platelet normalization occurred studies also reported a similar high proportion of patients earlier than other components of TMA response, observed 8 with extrarenal manifestations of aHUS. For instance, the days after the first ravulizumab dose; and data from this ALXN1210-aHUS-311 study, the adult equivalent to the clinical trial demonstrate improvement in efficacy of rav- current analysis, evaluating the efficacy and safety of rav- ulizumab with increasing treatment duration. ulizumab in adult patients with aHUS naïve to complement- Dialysis is burdensome and debilitating, having a severe inhibitor treatment, showed that 92.9% of patients had impact on the quality of life of children.21,22 With plasma extrarenal symptoms of aHUS before the first dose. This therapy, close to 50% of children develop end-stage kidney higher proportion of patients with extrarenal manifestations disease within 3 years of diagnosis.3,4 In this study, 83.3% reported in these recent studies could result from an increased children who were receiving dialysis at baseline had dis- awareness of aHUS as a disease, resulting in increased attri- continued dialysis at week 26, and, notably, 100% were off bution of these symptoms to aHUS, although an ascertain- dialysis by week 50, with no patients initiating dialysis during ment bias cannot be excluded as the presence of these the study. Overall, renal function improved substantially symptoms was specifically queried in these trials and not across the cohort, and all patients improved in eGFR category necessarily in earlier ones. Regarding pathogenic variants, the by week 50. As chronic kidney disease staging is not appli- rate of CFH-autoantibody–positive patients in this study was cable to children aged <2 years as a result of expected high at 7 (41%). Although it is a higher percentage than physiologic eGFR maturation, this terminology was not expected, it could have been related to the eligibility applied.23 requirement for being naïve to complement inhibition, as Because TMA leads to the involvement of the microvas- these patients may have been initially treated with alternative culature of other organs, aHUS can also manifest in neuro- therapies. It could also have been due to sampling error, as logical, gastrointestinal, cardiovascular, and pulmonary not all patients consented to genetic testing. systems.24–26 Thirteen (72.5%) patients in this study had Real-world evidence data from the Global aHUS Registry extrarenal symptoms at baseline, similar to the proportion have shown that dialysis requirement, recent hospitalizations, reported in the clinical trial of ravulizumab in adult patients use of plasma exchange/plasma infusion, and TMA have the naïve to complement inhibitor therapy.17 The term “extra- largest impact in reduced FACIT-Fatigue scores in patients renal symptom,” as applied in this trial, refers to any symp- with aHUS.27 In this study, all patients with evaluable data tom that may be related to aHUS occurring in an organ other had clinically meaningful improvement in FACIT-Fatigue than the kidney; this may include symptoms related to the score over time at week 26 and week 50. This improvement presence of renal failure. The patients in this trial were is especially important in patients with a chronic disease, such enrolled at the time of experiencing the primary acute as aHUS, and supports a favorable risk-to-benefit ratio of manifestations of aHUS and, thus, presented with severe treatment with ravulizumab. disease, evidenced by the number hospitalized and the The availability of a long-term treatment for aHUS that number requiring intensive care unit level of care. Other can be given at a reduced frequency compared with Kidney International (2021) 100, 225–237 231 clinical trial G Ariceta et al.: Ravulizumab efficacy and safety in pediatric aHUS Figure 6 | Serum-free C5 concentrations in patients <20 kg (a) and patients ‡20 kg (b) during the initial evaluation period and extension period (semi–log scale). Free C5 levels shown at the original loading dose of 300 mg for patients <10 kg. Horizontal line is drawn at free C5 at 0.5 mg/ml to denote the threshold for complete terminal complement inhibition. The horizontal line in the middle of each box indicates the median, a diamond indicates the mean, and the top border and the bottom border of the boxes mark the 75th and 25th percentiles, respectively. The whiskers represent the highest and lowest values within 1.5 times the interquartile range from the lower quartile and upper quartile. Outliers are represented by an asterisk. eculizumab has multiple potential benefits for patients. less sick, and experience reduced fear and pain from With a decrease from 26 infusions per year to 13 or 7 repeated venipuncture, and thus have an improved quality infusions (depending on body weight), patients and their of life with potentially greater adherence to treatment reg- caregivers will miss less time at school and work. Moreover, imens, although further studies are required to confirm children who may have required a port for vascular access these hypotheses. Recent data from the hemophilia B may no longer require a port, with reduced potential for literature point to the potential benefit of reduced dosing morbidity due to clots or infections and hospital workload. frequency on burden of therapy and reduced absenteeism Fewer clinic appointments could also reduce the risk of from school and work, in children treated with a long- exposure to nosocomial infections. Children may also feel acting recombinant factor IX.28 It is likely that similar 232 Kidney International (2021) 100, 225–237 G Ariceta et al.: Ravulizumab efficacy and safety in pediatric aHUS clinical trial Table 3 | Summary of AEs through current data cut Table 4 | Most frequent treatment-emergent adverse events Overall (N [ 21) Overall (N [ 21) AE variable No. (%) Events Adverse event No. (%) Events Any AE 21 (100) 369 Pyrexia 10 (47.6) 22 Any SAE 14 (66.7) 31 Nasopharyngitis 7 (33.3) 13 TEAE resulting in drug discontinuation 1 (4.8) 2 Diarrhea 7 (33.3) 10 TESAE resulting in drug discontinuation 1 (4.8) 2 Vomiting 7 (33.3) 25 TEAE resulting in study discontinuation 1 (4.8) 2 Headache 7 (33.3) 19 TESAE resulting in study discontinuation 1 (4.8) 2 Abdominal pain 6 (28.6) 11 TEAE during study drug infusion 4 (19.0) 7 Hypertension 6 (28.6) 8 TESAE during study drug infusion 0 0 Cough 5 (23.8) 6 Treatment-related AEs 10 (47.6) 33 Rash 4 (19.0) 5 Meningococcal infections 0 0 Rhinorrhea 4 (19.0) 4 Deaths 0 0 Myalgia 4 (19.0) 7 AE, adverse event; SAE, serious AE; TEAE, treatment-emergent AE; TESAE, treatment- Constipation 4 (19.0) 8 emergent SAE. Nausea 4 (19.0) 9 Events occurring in >15% of patients listed. Adverse event terms are as reported by the treating investigator. Patients evaluated for safety include all patients who received $1 dose of the study drug. benefits would be seen in children treated with rav- ulizumab. In terms of clinical benefits, fewer infusions This study was designed such that the primary end point could free up physician and nursing time in both homecare required hematologic and renal parameters to be met at 2 settings and in the clinic. In patients with aHUS, a recent separate assessments at least 28 days apart. This meant that productivity analysis in the United States shows that less patients discontinuing the study within 28 days of first dose frequent dosing with ravulizumab substantially reduces time were not able to meet this end point. However, this did not spent in treatment; the resulting lost productivity costs for have a significant impact on the results as only one patient ravulizumab treatment were 60% lower in the clinic and discontinued during the 26-week initial evaluation period 73% lower in home infusing setting, compared with ecu- (although this patient discontinued during the first 28 days lizumab treatment.29 This suggests that health system and and thus did not participate long enough to have responded societal costs with ravulizumab therapy are likely to be for any parameter). In addition, patients receiving dialysis at reduced, and quality of life resulting from increased time baseline were also unable to meet the renal end point until available for work and school is likely to improve.29 after stopping dialysis, because of serum creatinine level All patients who were enrolled in this study experienced at requirement. This could have led to a delay in time to achieve least one AE, with just under half (47.6%) experiencing a complete TMA response in some patients, although they treatment-related AEs. One patient discontinued the study had earlier clinical improvement. Also, 2 patients in the after experiencing SAEs of hypertensive crisis and worsening current analysis were aged <2 years, so interpretation of both anemia. After discontinuing the study, the investigator chose continuous and categorical eGFR data from these patients to treat her with an increased dose of eculizumab (600 mg) on should be approached with caution. Finally, because of the day 21 and day 23. rarity of the condition, limitations in patient enrollment and In the previous study of ravulizumab on adults naïve to sample size meant a comparator or control group was not complement treatment, AEs were reported in all patients, and feasible. SAEs were reported in 51.7%.17 The most common SAEs were viral gastroenteritis and abdominal pain, occurring in Conclusions 9.5% of patients each. These data are similar to those reported Ravulizumab provided immediate, complete, and sustained across the eculizumab trials in adults and children.7,19,20 complement C5 inhibition, resulting in rapid improvement in Specifically, in children, 90.9% and 59% in the eculizumab renal and hematologic parameters across 26 weeks, and trial experienced AEs and SAEs, respectively, similar to the further increase in response rate over longer duration, with proportions reported in the current study. The most common no unexpected safety concerns. Treatment with ravulizumab AEs in eculizumab-treated children were fever, cough, every 4 to 8 weeks provides patients and caregivers with a abdominal pain, diarrhea, and respiratory tract infection; and meaningful reduction in treatment burden. The results from the most common AEs in this study were pyrexia, headache, this study support the use of ravulizumab in children for nasopharyngitis, diarrhea, and vomiting. A recently published resolution of TMA caused by aHUS for a minimum treatment 10-year pharmacovigilance study showed that the main risk of period of 6 months. eculizumab is meningococcal infection.30 In the current study, no patients treated with ravulizumab developed METHODS meningococcal infections, consistent with previous eculizu- Trial oversight and study design mab clinical trials in children. Furthermore, no deaths were ALXN1210-aHUS-312 (NCT03131219) is a phase 3, single-arm, reported in this study. multicenter study to assess the efficacy and safety of ravulizumab Kidney International (2021) 100, 225–237 233 clinical trial G Ariceta et al.: Ravulizumab efficacy and safety in pediatric aHUS Figure 7 | ALXN1210-aHUS-312 study design and dosing schedule. aThe loading dose for patients <10 kg was increased from 300 to 600 mg following prespecified interim pharmacokinetic/pharmacodynamic analysis. The first 2 patients in this category received 300-mg loading dose. administered by intravenous infusion to pediatric (aged <18 years) Study population patients with active TMA and kidney injury who were naïve to Male or female patients, aged <18 years and weighing $5 kg at the complement inhibitor treatment. The protocol was approved by the time of consent, who had not been previously treated with com- Institutional Review Board or Independent Ethics Committee at all plement inhibitors were included if they had evidence of active TMA participating centers, and the study was conducted in accordance (hemolysis, thrombocytopenia, and kidney disfunction) per the with the Declaration of Helsinki and the Council for International following laboratory criteria: platelet count, <150  109/L; Organizations of Medical Sciences International Ethical Guidelines. LDH, $1.5 upper limit of normal; hemoglobin, lower limit of The patient’s legal guardian was required to provide written normal or less; and serum creatinine level, $97.5th percentile for age. informed consent, and the patient, written informed assent, where Key exclusion criteria were as follows: deficiency in a thrombo- applicable. spondin type 1 motif, member 13 (activity, <5%); Shiga toxin- The trial consisted of a screening period (up to 7 days), a 26- producing E coli hemolytic uremic syndrome; drug exposure– week initial evaluation period, and an extension period of 2 years related hemolytic uremic syndrome; hematopoietic stem cell trans- initially, which was increased to 4.5 years by protocol amendment. plant within last 6 months before start of screening; known genetic Ravulizumab dosing was weight based, with each intravenous defects of cobalamin C metabolism; or other conditions associated infusion given over a period of approximately 2 hours. A loading with TMA (Supplementary Materials). Patients receiving immuno- dose was administered, followed by maintenance doses on day 15 suppressive therapies were excluded unless specifically for post- and then every 4 to 8 weeks, depending on body weight transplantation therapy, the patient had anticomplement anti- (Figure 7). Baseline was defined as the period from initial bodies, or corticosteroids were being used for another medical screening until the first study drug infusion, including day 1. condition. Patients receiving plasma exchange/plasma infusion for a Because of the clinical urgency of patients in this analysis, some period of $28 days before screening were excluded (plasma ex- patients could have received the loading dose before confirmation change/plasma infusion was allowed up to the first dose of rav- of eligibility on the basis of central laboratory results and before ulizumab, but not thereafter). Patients receiving long-term dialysis receiving Shiga toxin-producing E coli and a thrombospondin type (dialysis on a regular basis for end-stage kidney disease) were also 1 motif, member 13, test results. All patients were required to excluded. Patients previously treated with complement inhibitors have vaccination against Neisseria meningitidis, before or at the were also excluded. Full details of inclusion and exclusion criteria are time of initiating the study drug. listed in the Supplementary Materials. 234 Kidney International (2021) 100, 225–237 G Ariceta et al.: Ravulizumab efficacy and safety in pediatric aHUS clinical trial Patients must have had vaccination against N meningitidis within ravulizumab, had at least one postbaseline efficacy assessment, 3 years before or at the time of initiating the study drug, according to and satisfied specific eligibility criteria that may have been veri- local and national guidance, as well as vaccination against Strepto- fied only after receiving their first dose. The full analysis set was coccus pneumoniae and Haemophilus influenzae. Sexually active fe- determined before database lock and before database snapshot male patients were required to use highly effective contraception for the analysis performed at the end of the 26-week initial from screening until at least 8 months after the last dose of rav- evaluation period. ulizumab and were counseled about avoiding pregnancy during the The primary end point, complete TMA response during the 26- study period. Patients who received a meningococcal vaccine at study week initial evaluation period, was summarized by number and initiation or <2 weeks before initiating treatment with ravulizumab proportion of complete TMA responders (with 2-sided 95% confi- were treated with appropriate prophylactic antibiotics until 2 weeks dence interval) in patients treated with ravulizumab. Complete TMA after vaccination. Patients who had not been vaccinated before response through week 50 was also assessed and included all avail- initiating ravulizumab treatment should have received prophylactic able follow-up. antibiotics before meningococcal vaccination and for at least 2 weeks The secondary end point analyses included a production of after. Long-term antibiotic prophylaxis beyond these minimum re- Kaplan-Meier distribution of time to complete TMA response. quirements was based on the practice of the treating physician. Complete TMA response status over time was summarized by presenting the number and proportion of patients achieving Efficacy end points response. Dialysis requirement status, the proportion of pa- The primary end point was complete TMA response during the 26- tients requiring and no longer requiring dialysis, was calculated week initial evaluation period. TMA response was defined by the (with 2-sided 95% confidence interval). eGFR value and change following criteria: normalization of platelet count ($150  109/L), from baseline were summarized using descriptive statistics. normalization of LDH (#246 U/L), and $25% improvement in eGFR category was summarized over time, presenting the serum creatinine from baseline. Participants had to meet all com- number and proportion of patients who improved, worsened, plete TMA response criteria at 2 separate assessments obtained at and stayed the same compared with eGFR category at base- least 28 days apart, and any measurement in between. The primary line.23 Hematologic parameters (platelets, LDH, and hemoglo- end point was identical to that used in the pediatric eculizumab bin) were summarized using descriptive statistics for observed clinical trial.7 In cases of a patient receiving dialysis at baseline, the value and change from baseline. The number and proportion of first baseline serum creatinine value that was used was the first patients with an increase from baseline in hemoglobin $20 g/L, available $6 days after dialysis. For patients receiving dialysis observed at 2 separate assessments obtained at least 28 days throughout the initial evaluation period, no baseline serum creati- apart, were summarized. The number and proportion of pa- nine was calculated during this period, and the renal response tients with at least a 3-point improvement from baseline for component of the analysis was deemed not achieved. eGFR in these Pediatric FACIT-Fatigue were also summarized at each time patients was set to 10 ml/min per 1.73 m2. point. The secondary end points of the trial included time to complete PK/PD analyses were performed in all patients with evaluable PK/ TMA response; complete TMA response status over time; observed PD data who had received at least one infusion of ravulizumab. value and change from baseline in hematologic parameters (platelets, All hematologic, renal, and quality-of-life efficacy end points LDH, and hemoglobin); proportion of patients with an increase from were assessed through week 50. baseline in hemoglobin $20 g/L; observed value and change from Safety analyses were performed for the safety set, defined as all baseline in eGFR (calculated per the Schwartz formula); eGFR cate- patients who received at least one dose of ravulizumab. All AEs, gory, as evaluated by eGFR at select target days; dialysis requirement coded using MedDRA Version 18, were summarized by organ system status; and change from baseline in Pediatric FACIT-Fatigue ques- class and preferred term. The data cut point for safety considered all tionnaire (patients aged $5 years only). The PD and PK end points available follow-up. included serum ravulizumab concentration and serum-free C5 con- centrations over time (Supplementary Materials). Free C5 <0.5 mg/ml APPENDIX indicates complete terminal complement inhibition.31,32 Members of the 312 Study Group Exploratory whole exome sequencing of complement pathogenic Helen Lovell (University of Nebraska Medical Center, Nebraska, USA), Melissa variants was conducted on the Novaseq 6000 platform with a 2  Muff-Luett (University of Nebraska Medical Center, Nebraska, USA), Kristin 150-bp paired-end module (Illumina Inc., San Diego, CA, USA). Malone (University of Nebraska Medical Center, Nebraska, USA), Oluwasegun Determination of pathogenesis is further detailed in the Adeagbo (Emory University School of Medicine and Children’s Healthcare of Supplementary Materials. Atlanta, Atlanta, Georgia, USA), Alexandria Wilkerson (Emory University School of Medicine and Children’s Healthcare of Atlanta, Atlanta, Georgia, USA), Gloria Fraga (University Hospital Vall d’Hebron, Barcelona, Spain), Safety end points Scherezade Sarri (University Hospital Vall d’Hebron, Barcelona, Spain), Hae Il The safety of ravulizumab was evaluated by the incidence of AE and Cheong (Division of Pediatric Nephrology, Department of Pediatrics, Seoul SAEs. The proportion of patients who developed antidrug antibodies National University College of Medicine, Seoul, Korea), Yo Han Ahn (Division of Pediatric Nephrology, Department of Pediatrics, Seoul National University was also assessed. AEs were coded using MedDRA Version 21.0 and College of Medicine, Seoul, Korea), Kyoung Hee Han (Jeju National Univer- graded using Common Terminology Criteria for Adverse Events sity, School of Medicine, Korea), Elke Wühl (University Hospital Heidelberg (CTCAE) Version 4.03. Physical examinations, vital signs, electro- for Pediatric and Adolescent Medicine, Heidelberg, Germany), Gianluigi cardiograms, and laboratory assessments were also noted. Ardissino (Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy), Valentina Capone (Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy), Alexandru Constantinescu (Joe DiMaggio Statistical analyses Children’s Hospital, Hollywood, FL, USA), Ivy Boydstun (Joe DiMaggio Chil- Efficacy analyses were performed on the full analysis set, which dren’s Hospital, Hollywood, FL, USA), Reem Raafat (Joe DiMaggio Children’s included all patients who received at least one dose of Hospital, Hollywood, FL, USA), Marezhe Mersha (Joe DiMaggio Children’s Kidney International (2021) 100, 225–237 235 clinical trial G Ariceta et al.: Ravulizumab efficacy and safety in pediatric aHUS Hospital, Hollywood, FL, USA), Belkis Wandique-Rapalo (Joe DiMaggio Chil- Table S4. All serious adverse events reported during the study. dren’s Hospital, Hollywood, FL, USA), Hiroshi Hataya (Tokyo Metropolitan Figure S1. Graphical representation of the mechanism of Children's Medical Center, Tokyo, Japan), Dr. Hamada (Tokyo Metropolitan ravulizumab half-life prolongation. Children's Medical Center, Tokyo, Japan), Dr. Terano (Tokyo Metropolitan Children's Medical Center, Tokyo, Japan), Lesley Rees (Great Ormond Street Hospital, London, UK), Araceli Garcia Pose (Hospital Universitario Infanta Sofía, Madrid, Spain), Inés Vergara Pérez (Hospital Universitario Infanta Sofía, REFERENCES Madrid, Spain), Mercedes Cao Vilariño (Hospital Universitario Infanta Sofía, 1. Fakhouri F, Zuber J, Fremeaux-Bacchi V, Loirat C. Haemolytic uraemic Madrid, Spain), Brigitte Adams (Hôpital Universitaire des Enfants Reine syndrome. Lancet. 2017;390:681–696. Fabiola, Brussels, Belgium), and Tram Nathalie (Hôpital Universitaire des 2. Goodship TH, Cook HT, Fakhouri F, et al. 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