Articles

Asfotase alfa for infants and young children with hypophosphatasia: 7 year outcomes of a single-arm, open-label, phase 2 extension trial

Michael P Whyte, Jill H Simmons, Scott Moseley, Kenji P Fujita, Nicholas Bishop, Nada J Salman, John Taylor, Dawn Phillips, Mairead McGinn, William H McAlister

Summary Background Our previous phase 2, open-label study of 11 infants and young children with life-threatening perinatal or Lancet Diabetes Endocrinol infantile hypophosphatasia showed 1 year safety and efficacy of asfotase alfa, an enzyme replacement therapy. We 2019; 7: 93–105 aimed to report the long-term outcomes over approximately 7 years of treatment. Published Online December 14, 2018 http://dx.doi.org/10.1016/ Methods We did a prespecified, end of study, 7 year follow-up of our single-arm, open-label, phase 2 trial in which S2213-8587(18)30307-3 children aged 3 years or younger with life-threatening perinatal or infantile hypophosphatasia were recruited from This online publication has been ten hospitals (six in the USA, two in the UK, one in Canada, and one in the United Arab Emirates). Patients received corrected. The corrected version asfotase alfa (1 mg/kg three times per week subcutaneously, adjusted to 3 mg/kg three times per week if required) for first appeared at thelancet. up to 7 years (primary treatment period plus extension phase) or until the product became commercially available; com/diabetes-endocrinology on January 22, 2019 dosage adjustments were made at each visit according to changes in the patient’s weight. The primary objectives of See Comment page 76 this extension study were to assess the long-term tolerability of asfotase alfa, defined as the number of patients with Center for Metabolic Bone one or more treatment-emergent adverse events, and skeletal manifestations associated with hypophosphatasia, Disease and Molecular evaluated using the Radiographic Global Impression of Change (RGI-C) scale (−3 indicating severe worsening, and Research, Shriners Hospital for +3 complete or near-complete healing). Respiratory support, growth, and cognitive and motor functions were also Children, St Louis, MO, USA evaluated. All efficacy and safety analyses were done in all patients who received any asfotase alfa (full-analysis (Prof M P Whyte MD); Division of Bone and Mineral Diseases, population). This study and extension phase are registered with ClinicalTrials.gov, number NCT01205152, and Department of Internal EudraCT, number 2009-009369-32. Medicine, Washington University School of Medicine Findings 11 participants were recruited between Oct 6, 2008, and Dec 4, 2009. Ten patients completed a 6 month at Barnes-Jewish Hospital, St Louis, MO, USA treatment period and entered the extension phase; nine received asfotase alfa for at least 6 years and completed the (Prof M P Whyte); Vanderbilt study, with four being treated for more than 7 years. Skeletal healing was sustained over 7 years of treatment; all University Medical Center, evaluable patients had RGI-C scores of at least +2 at year 6 (n=9; median score +2·0 [range 2·0–3·0]) and year 7 (n=7; Department of Pediatrics, median score +2·3 [2·0–3·0]). No patient who completed the study required respiratory support after year 4. Weight Vanderbilt University, Nashville, TN, USA Z scores improved to within normal range from year 3 to study end; length or height Z scores improved but remained (J H Simmons MD); Alexion below normal. Age-equivalent scores on gross motor, fine motor, and cognitive subscales of the Bayley Scales of Pharmaceuticals, Boston, MA, Infant and Toddler Development also improved. All 11 patients had at least one treatment-emergent adverse event. USA (S Moseley MS, The most common adverse events were pyrexia (eight [73%] of 11 patients), upper respiratory tract infection K P Fujita MD); Sheffield Children’s Hospital, Sheffield, (eight [73%]), craniosynostosis (seven [64%]), and pneumonia (seven [64%]). Serious adverse events related to asfotase UK (Prof N Bishop MD); alfa occurred in three (27%) patients (severe chronic hepatitis; moderate immediate post-injection reaction; and Tawam Hospital, Al Ain, United severe craniosynostosis with severe conductive deafness). Arab Emirates (N J Salman MD); Prevea Health Clinic, Hospital Sisters Health System Interpretation Patients with perinatal or infantile hypophosphatasia treated with asfotase alfa for up to 7 years showed St Vincent Hospital, Green Bay, early, sustained improvements in skeletal mineralisation. Respiratory function, growth, and cognitive and motor WI, USA (J Taylor DO); Division function also improved, and asfotase alfa was generally well tolerated. of Physical Therapy, University of North Carolina, Chapel Hill, NC, USA (D Phillips PhD); Funding Alexion Pharmaceuticals, Inc. Royal Belfast Hospital for Sick Children, Belfast, UK Copyright © 2018 Elsevier Ltd. All rights reserved. (M McGinn MD); and Mallinckrodt Institute of Radiology, Washington Introduction pyrophosphate (PPi) and pyridoxal 5’-phosphate University School of Medicine, Hypophosphatasia is the rare, inherited, metabolic (PLP).1,3–5 PPi potently inhibits mineralisation by St Louis, MO, USA bone disease caused by loss-of-function mutations of blocking hydro­xyapatite crystal form­ation.6,7 Thus, the (Prof W H McAlister MD) the alkaline phosphatase biomineralisation-associated super­abundance of PPi in hypophosphatasia­ often gene (ALPL) that encodes the tissue non-specific leads to rickets during growth.6,7 TNSALP dephos­ isoenzyme of alkaline phosphatase (TNSALP).1,2 Low phorylates PLP (the principal circulating form of TNSALP activity on cell surfaces results in extracellular vitamin B6) to pyridoxal, which allows the compound to accumulation of its substrates, including inorganic cross cell plasma membranes and be rephosphorylated­ www.thelancet.com/diabetes-endocrinology Vol 7 February 2019 93 Downloaded for Anonymous User (n/a) at President and Fellows of Harvard College on behalf of Harvard University from ClinicalKey.com by Elsevier on February 19, 2019. For personal use only. No other uses without permission. Copyright ©2019. Elsevier Inc. All rights reserved. Articles

Correspondence to: Prof Michael P Whyte, Center for Research in context Metabolic Bone Disease and Molecular Research, Shriners Evidence before this study with hypophosphatasia receiving treatment with asfotase alfa. Hospital for Children, St Louis, In 2012, we reported the 1 year findings from the first open-label, The early improvements were sustained for up to 7 years of MO 63110, USA phase 2, multinational study that evaluated the safety and efficacy treatment. Typically, the improved skeletal mineralisation [email protected] of asfotase alfa, an enzyme replacement therapy, in infants and during the first 6 months of treatment was followed by young children with the life-threatening perinatal or infantile withdrawal of respiratory support, and was then associated forms of hypophosphatasia, a heritable metabolic bone disease. with improved motor and cognitive function that persisted Clinically significant healing of the skeleton was accompanied by until study end. Although most patients had required improved respiratory function and developmental milestones, prolonged pulmonary support, all nine who completed the and this drug was generally well tolerated. At that time, study no longer needed it after year 4. For most patients, no treatment was approved for hypophosphatasia, and improvements in length or height and weight Z scores management of the disease involved supportive care. Asfotase indicated catch-up growth. Improvements from baseline in alfa was approved multinationally in 2015, based in part on the gross motor, fine motor, and cognitive function reached levels findings from this pivotal open-label study. In a 2016 publication, that could match those of healthy peers. Asfotase alfa was these same patients had improved survival and respiratory generally well tolerated, with the most common outcomes compared with historical controls. In another 2016 treatment-emergent adverse events consistent with sequelae study, older children with symptomatic hypophosphatasia of hypophosphatasia. No evidence of resistance to the therapy showed sustained improvement in skeletal mineralisation, with emerged. most achieving normal values for age-matched and sex-matched Implications of all the available evidence peers in growth, strength, and motor function during 5 years of This now completed study documents long-term safety and treatment with asfotase alfa. efficacy of asfotase alfa treatment for infants and young Added value of this study children with life-threatening hypophosphatasia. The findings This Article reports long-term follow-up data since the initial complement observations from the 5 year study of the 2012 publication. The impact of asfotase alfa treatment is treatment of older children with hypophosphatasia. For presented for infants and young children with life-threatening life-threatening paediatric-onset hypophosphatasia, prompt hypophosphatasia who were given a median of 6·6 years of diagnosis and commencement of asfotase alfa treatment can therapy, representing the longest follow-up to date in patients rescue such patients and give them enjoyable health.

intra­cellularly to PLP. Therefore, vitamin B6-dependent manifested complications of hypophosphatasia before seizures occur in some infants who are severely affected age 6 months, including skeletal abnormalities, such as by hypophosphatasia.4,7–9 Life-threatening complications shortened or bowed limbs, rachitic chest deformity, in the severe perinatal and infantile forms of hypo­ fractures, osteopenia, craniosynostosis, or other rachitic phosphatasia can include respiratory failure from findings. All but one patient had failure to thrive, most rachitic chest deformity and rib fractures, elevated patients (nine [82%] of 11) required respira­tory support, intracranial pressure due to cranio­synostosis, and and all had gross motor delay. A single 2 mg/kg hypercalcaemia leading to nephro­calcinosis and renal intravenous infusion of asfotase alfa preceded sub­ compromise.7,10–12 Other potential complications of cutaneous injections, starting at 1 mg/kg three times per paedi­atric hypophosph­atasia include long-bone de­ week. Results from this study published in 2012 showed formity and muscle weakness.7,10 Historically, perinatal outcomes after 12 months or longer (range 12–26) of hypophosphatasia has been considered lethal, and treatment with asfotase alfa.18 One patient had consent infantile hypophosphatasia has around 50% mortality withdrawn on day 1 because of infusion-associated during the first year of life.13–15 reactions, and one patient died of pneumonia and sepsis Asfotase alfa (Strensiq, Alexion Pharmaceuticals, after 7·5 months of treatment.18,19 The study met its Boston, MA, USA) is a human, recombinant, TNSALP primary efficacy measure of change in hypo­phosphatasia replacement therapy that was approved multinationally skeletal disease severity from baseline to month 6 on the in 2015, typically for the treatment of paediatric-onset basis of assessment of skeletal radiographs using the hypophos­pha­tasia.16,17 The safety and efficacy of asfotase validated 7 point Radiographic Global Impression of alfa were first evaluated during our phase 2, open-label Change (RGI-C) scale (median +2·0, minimum 0, maxi­ study in paediatric patients aged 3 years or younger with mum +2·3; p=0·004). Skeletal healing was accompanied life-threatening perinatal or infantile hypophosphatasia.18 by improvements in secondary outcome measures of This study enrolled 11 patients with hypophosphatasia respiratory and motor function over 1 year of treatment. (five with perinatal hypophosphatasia and six with Asfotase alfa was generally well tolerated.18 infantile hypophosphatasia) ranging in age from 2 weeks In this Article, we report the long-term efficacy to 3 years for the 6 month initial trial.18 Patients (skeletal manifestations, respiratory support, growth,

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and motor and cognitive function), pharmacodynamics, the 10 point Rickets Severity Scale (RSS; from 0, and safety after approximately 7 years of treatment with indicating absence of metaphyseal cupping and fraying, asfotase alfa. to 10, indicating severe rickets; maximum of 4 points for wrists and 6 points for knees), developed and Methods validated to assess nutritional rickets in children (mean Study design and participants age 4·5 years).21 All individuals who rated RGI-C and In this Article, we present the prespecified 7 year RSS were masked to all treatment timepoints (except follow-up of our single-arm, open-label, phase 2 trial. baseline radiographs for RGI-C) and all other patient The trial design, including patient inclusion and information. exclusion criteria, has been published elsewhere.18 The Use of supplemental oxygen, continuous positive patient numbering scheme used in our previous publi­ airway pressure (CPAP), biphasic positive airway pres­ cation is continued in this report. Briefly, this study sure (BiPAP), and mechanical ventilation was docu­ was done at ten hospitals (six sites in the USA, mented at each study visit. two in the UK, one in Canada, and one in the Length or height, weight, and head circumference were United Arab Emirates). Key eligibility criteria were age recorded at study visits. Z scores for length or height and 3 years or younger, and a documented diagnosis of weight were established using US Centers for Disease severe hypophosphatasia with symptoms occurring Control and Prevention growth charts for age-matched before the age of 6 months.18 and sex-matched healthy infants and children.22 Head The investigation was authorised at each study site circumference Z scores were calculated using WHO through appropriate research governance and ethics formulae.23 processes. Parents and legal guardians signed the Depending on the patient’s age and functional abilities written consent form before study participation. at individual visits, each site’s physical therapist, in consultation with the medical monitor, established the Procedures appropriate assessment or combination of assessments of In the 6 month primary treatment period, safety and motor and cognitive development, which included the efficacy of asfotase alfa were assessed. A single 2 mg/kg following: the Bayley Scales of Infant and Toddler intravenous infusion of asfotase alfa preceded 1 mg/kg Development, third edition (BSID-III); the Peabody subcutaneous injections of asfotase alfa three times per Developmental Motor Scales, second edition (PDMS-2); week (total dose 3 mg/kg per week). The dosage could or the Bruininks-Oseretsky Test of Motor Proficiency, be increased to up to 3 mg/kg three times per week second edition (BOT-2; appendix). Patients aged 42 months See Online for appendix (total dose 9 mg/kg per week) after 1 month if the or younger, or those who were older but with severe treatment was not effective, defined as worsening of develop­mental delays, were assessed using the gross failure to thrive, deteriorating pulmonary function, or motor, fine motor, and cognitive subscales of the no radio­graphic evidence of skeletal improvement. The BSID-III.24 If patients showed cognitive age equivalence of extension phase continued the subcutaneous asfotase 42 months, such testing was discontinued. Patients aged alfa dosage from the primary treatment period; dosage 43–71 months who were considered to have evaluable adjustments were made at each visit according to functional abilities were studied using the locomotion changes in the patient’s weight. Additional dosage subtest of the PDMS-2, an assessment of gross motor adjustments (no limits on maximum dose) were skills.25 Patients aged 72 months or older with evaluable permitted if the treatment was not effective or for functional abilities completed the running speed, agility, safety-related concerns. Patients continued to receive and strength subtests of the BOT-2, an assessment of asfotase alfa for up to 7 years (primary treatment period gross motor proficiency.26 Licensed physical therapists, or plus extension phase) or until the product became their local equivalents, did the assessments at baseline commercially available, whichever occurred first. (BSID-III only), month 3 (BSID-III only), month 6, year 1, Hypophosphatasia skeletal manifestations were and every 6 months thereafter. When possible, these evalu­ated using sequential radiographs of the chest, functional assessments occurred before same-day invasive wrists, and knees, obtained at baseline, months 1, 3, 6, tests or examinations that could tire the patient. and 9, and years 1, 1·5, 2, 2·5, 3, 4, 5, 6, and 7. At each Blood was collected for assay of serum alkaline phos­ timepoint, the same three paediatric radiologists pha­tase (ALP) activity, plasma PPi and PLP con­ independently rated changes compared with baseline centrations, and serum intact parathyroid hormone at using the RGI-C scale (–3 indicating severe worsening, baseline, month 3, month 6, month 9, year 1, and every 0 no change, and +3 complete or near-complete 6 months thereafter. Treatment samples were collected healing), which has been validated in paediatric patients before asfotase alfa dosing and after patients had fasted with hypophosphatasia.20 The mean of the RGI-C scores for at least 4 h. The tubes for blood sampling of PPi and was calculated for each patient at each timepoint. PLP contained leva­misole to inhibit the high ALP A separate rater independently evaluated the radio­ activity from asfotase alfa. Laboratory samples were graphs of the wrists and knees at each timepoint using managed by a central facility (Covance, Indianapolis, www.thelancet.com/diabetes-endocrinology Vol 7 February 2019 95 Downloaded for Anonymous User (n/a) at President and Fellows of Harvard College on behalf of Harvard University from ClinicalKey.com by Elsevier on February 19, 2019. For personal use only. No other uses without permission. Copyright ©2019. Elsevier Inc. All rights reserved. Articles

IN, USA, and Geneva, Switzerland). PPi analyses were were done using the full-analysis population, which done by Alexion Montreal Corporation (Montreal, QC, included all patients who received any asfotase alfa. For Canada) and Charles River Laboratories (Senneville, the purposes of this study, the full-analysis population QC, Canada). PLP analyses were done at two central and intent-to-treat population were identical. Analyses laboratories (ARUP Laboratories, Salt Lake City, UT, of the secondary endpoints will include all patients with USA, and Biotrial Bioanalytical Services, Laval, QC, available data at each timepoint. Some analyses were Canada). Reported PLP results were not censored for repeated using the per-protocol population, which vitamin B6 supplementation, which can markedly included all patients who received any asfotase alfa and increase PLP in patients with hypophosphatasia.­ 27 did not have any major protocol deviations considered Additional details regarding the PPi and PLP assays are to potentially influence treatment effect. Because of provided in the appendix. the timing of study visits, annual timepoints were Adverse events, including injection site reactions approximated, with 48 weeks defined as 1 year. (ISRs) and injection-associated reactions (IARs), were Median (minimum, maximum) values were con­tinuously monitored. ISRs were defined as adverse calculated for the RGI-C and RSS scores, length or events localised to the site of asfotase alfa admini­ height, weight, and head circumference raw values and stration, and IARs were defined as systemic signs, Z scores, and BSID-III scaled scores over time. A one- symptoms, or findings (eg, chills, cough, and erythema) sample Wilcoxon signed-rank test using a two-sided occurring within 3 h after asfotase alfa administration. α of 0·05 was used to test whether the median RGI-C The site investigator assessed the possible, probable, or score at each timepoint differed from 0 (ie, no change). definite relationship of adverse events to the study The proportion of patients with RGI-C scores of +2 or drug. Additional safety asses­sments included physical +3 (so-called RGI-C responders) was calculated for examin­ation findings, laboratoryvalues (including each timepoint. Mean changes from baseline in calcium and phosphate), and asfotase alfa antibody Z scores for length or height and weight were analysed testing results (done by Cambridge Biomedical, using a one sample t test. Age-equivalent and scaled Boston, MA, USA, and PPD Laboratories, Richmond, (or standard) scores were calculated for each subscale VA, USA). Patients were assessed­ for ectopic calcifi­ or subtest of the BSID-III, PDMS-2, and BOT-2. Scaled cation by periodic funduscopic examinations (changed or standard scores for each subscale or subtest were to full ophthalmological examin­ations by protocol then compared with the normative mean and SD amendment after about 1·5 years) and periodic renal values for healthy age-matched peers, which were ultrasounds. 10 (SD 3) for the BSID-III scaled score,24 10 (3) for the PDMS-2 standard score,25 and 15 (5) for the BOT-2 Outcomes running speed and agility subtest scaled score.26 These In this extension trial, the primary safety outcome was functional measures were exploratory and therefore the long-term tolerability of asfotase alfa, defined as the not analysed statistically. number of patients with one or more treatment- Pharmacodynamic and safety outcome measures are emergent adverse events. The primary efficacy outcome summarised descriptively. SAS version 9.4 (Cary, NC, was long-term skeletal manifestations of hypo­ USA) was used for all statistical analyses. phosphatasia, as measured using the RGI-C scale as This extension trial is registered with ClinicalTrials.gov, previously described. Secondary outcome measures number NCT01205152, and EudraCT, number were long-term pharmacodynamics­ of asfotase alfa, the 2009-009369-32. The study was overseen by a data effect of asfotase alfa on growth and development, monitoring committee. survival, respiratory function, and other clinical signs and symptoms of hypo­phosphatasia in infants and Role of the funding source young children. The funder was involved in all stages of the study conduct and analysis, including the study design, data Statistical analyses collection, data analysis, data interpretation, and As published elsewhere,18 the sample size for this study writing of this report. The corresponding author had reflected findings from a previous study21 showing the full access to all the data in the study and had final correlation of a 10-point RSS with severity of nutritional responsibility to submit for publication. rickets, with variability of approximately 0·75 points. Assuming similar variability in a population of patients Results with hypophosphatasia and a sample size of six patients, 11 patients were enrolled between Oct 6, 2008, and pretreatment versus post-treatment radio­graphic differ­ Dec 4, 2009, and received at least one dose of asfotase ences must be at least 1·9 points for 80% power to alfa (median age at enrolment 30 weeks [range 3–158; detect a significant difference. This number was seven [64%] girls and four [36%] boys). All ten patients increased to ten patients to establish changes after who completed the 6 month primary treatment period 24 weeks of treatment. All efficacy and safety analyses entered the extension phase; nine patients received

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asfotase alfa for at least 6 years and completed the criterion (ALP activity at least 3 SDs below the mean study, with four of the nine patients being treated for ALP activity for that age). One patient did not meet the more than 7 years. The median duration of treatment failure-to-thrive eligibility criterion (participant was too for the 11 enrolled patients was 6·6 years (range 1 day to young developmentally for assessment) and received a 7·5 years). Patient demographics, baseline character­ fixed dose of asfotase alfa that was not adjusted to istics, and efficacy and safety outcomes after at least weight (received subcutaneous injections of 8 mg 1 year of treatment for the nine patients who were asfotase alfa three times per week) from approximately treated for at least 6 years in the current trial and week 9 until his death at 7·5 months, with his last detailed case reports of all 11 enrolled patients have recorded weight being 5·7 kg. One patient had dosage been published elsewhere.18 Updated narratives for all increases for failure to thrive on day 22 (from 1 mg/kg patients who completed the study are provided in the three times per week to 1·5 mg/kg [one dose only]) and appendix. day 24 (from 1·5 mg/kg to 3 mg/kg three times per Four patients had major protocol deviations con­ week); dose increases were not permitted per protocol sidered to potentially influence treatment effect and before completion of 1 month of treatment. were there­fore excluded from the per-protocol popu­ Because primary efficacy outcomes (RGI-C scores at lation. Two patients did not meet the ALP eligibility month 6) were similar between the full-analysis and

A Responders (%) 0107089 100 75 100 100 100 100 Complete or +3·0 p=0·004 +3·0 near-complete Responder (≥+2) +2·7 p=0·008 healing (+1·3 to +3·0) +2·5 p=0·063 p=0·016 (+1·7 to +3·0) +2·3 +2·3 +2·5 p=0·004 p=0·004 (+2·0 to +2·7) p=0·004 p=0·004 (+2·0 to +3·0) +2·0 +2·0 +2·0 +2·0 (0 to +2·3) (+2·0 to +3·0) (+2·0 to +3·0) (+2·0 to +3·0) Substantial +2·0 +2·0 healing

p=0·031 +1·5 +1·2 (–1·0 to +2·0) Minimal +1·0 +1·0 healing Median (range) RGI-C score

p=0·063 +0·5 +0·2 (0 to +1·0) n=10 n=10 n=10 n=9 n=9 n=8 n=5n=9 n=9 n=7 0 0·0 No change

B 10·0 10·0 Severe rickets 8·3 9·0 p=0·500 (5·5 to 10·0) p=0·203 7·5 7·3 8·0 (5·5 to 10·0) (4·5 to 10·0) 7·0

6·0 p=0·016 5·0 4·0 5·0 (0·5 to 10·0) 4·0

Median (range) RSS score 3·0 p=0·008 1·5 p=0·008 2·0 p=0·016 (0 to 10·0) 1·0 0·8 p=0·063 p=0·004 p=0·004 p=0·016 (0 to 10·0) (0 to 10·0) 0·5 0·5 0·5 0·5 1·0 (0 to 3·0) (0 to 6·0) (0 to 6·0) (0 to 5·5) Absence of n=10 n=10 n=10 n=9 n=9 n=9 n=8n=5 n=9n=9 n=7 metaphyseal 0 0·0 cupping and Baseline Month 1 Month 3 Month 6 Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 fraying

Months of treatment Years of treatment

Figure 1: Median RGI-C scores and RSS scores over time in infants and young children with hypophosphatasia treated with asfotase alfa (A) Median (range) in RGI-C scores across the treatment period. An RGI-C score of +2 (substantial healing of hypophosphatasia rickets) or higher (complete healing) was classified as RGI-C responders.18 (B) Median (range) RSS scores across the treatment period. p values are for the comparison with baseline. RGI-C=Radiographic Global Impression of Change. RSS=Rickets Severity Scale. www.thelancet.com/diabetes-endocrinology Vol 7 February 2019 97 Downloaded for Anonymous User (n/a) at President and Fellows of Harvard College on behalf of Harvard University from ClinicalKey.com by Elsevier on February 19, 2019. For personal use only. No other uses without permission. Copyright ©2019. Elsevier Inc. All rights reserved. Articles

per-protocol populations (data not shown), we present Median RSS scores indicated that the improvements results after 6–7 years of asfotase alfa treatment for the documented as early as month 618 were sustained over full-analysis population only. 7 years of treatment, with significant (p<0·05) decreases Median RGI-C scores documented improvements in indicating improvement from baseline at most visits hypophosphatasia skeletal disease as early as month 3, (figure 1B). which were typically sustained over 7 years of treatment, All ten patients who entered the extension phase had an with significant (p<0·05) improvements at most visits overall RGI-C score at last assessment that ranged from (figure 1A). The proportion of evaluable patients with +2 (substantial healing) to +3 (complete or near-complete RGI-C scores of at least +2 (responders) was healing). The substantial improvements in radiographic eight (89%) of nine patients at year 1 and seven (100%) of findings for the wrists and knees in two patients treated seven patients at year 7. The highest possible RGI-C with asfotase alfa over 7 years of treatment are illustrated score of +3 was achieved by four patients, with in the representative images in figure 2. Illustrative three first achieving a +3 score by year 1 and one first radiographs for all patients are included in the appendix. achieving a +3 by year 2; all four patients maintained Duration of respiratory support was published in scores of at least +2 at all timepoints thereafter. 2016.15 for the six patients from this study requiring

A Patient 1

Baseline Month 6Year 6·5

B Patient 2

Baseline Month 6Year 6·5

Figure 2: Representative radiographic changes from baseline to year 6·5 in two patients treated with asfotase alfa Radiographic changes are illustrated for the left wrist of patient 1 (A) and the right knee of patient 2 (B). For both patients at baseline, markedly widened physes with indistinct provisional zones of calcification, metaphyseal flaring (arrows), and generalised osteopenia consistent with severe rickets can be observed. Substantial improvements are apparent at month 6 of asfotase alfa treatment, and these improvements are sustained after 6·5 years of therapy.

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CPAP, BiPAP, or mechanical ventilation, with a Mechanical ventilation Non-invasive* None Data not available Death Alive at study end maximum follow-up of 6 years. Respiratory support Patient Baseline over time is summarised for all 11 patients (figure 3). At age (weeks) baseline, five (45%) of 11 patients required respiratory 1† 33 support, with three (27%) of 11 requiring mechanical ventilation, one (9%) of 11 receiving CPAP, and one 2† 28 (9%) of 11 receiving supplemental oxygen. By year 2, 3† 142 three (33%) of nine patients required respiratory 4† 82 Consent withdrawn for moderate infusion reaction support, with one (11%) of nine requiring mechanical 5 158 ventilation, and two (22%) of nine receiving just 6† 3 Death due to unrelated sepsis supplemental oxygen. From 4·5 years of treatment 7 5 until study end, none of the nine patients required 8 133 respiratory support (including supple­mental oxygen). 9† 30 Median length or height was 56·5 cm (range 39·0–83·0) at baseline (n=11) and 112·5 cm 10 11 (88·1–123·0) at year 7 (n=7). The median length or 11 21 height Z score was higher than at baseline from month Baseline 1 2 3 4 5 6 7 6 until year 7, although this value remained more than Years of treatment 2 SDs below the mean for healthy age-matched and sex- Figure 3: Respiratory support for infants and young children with hypophosphatasia treated with matched peers at all timepoints (figure 4). Overall, asfotase alfa four (44%) of nine patients had Z scores within the *Non-invasive respiratory support included CPAP, BiPAP, and supplemental oxygen. †Data through year 6 15 normal range at last assessment. The mean increase was reported previously for the six patients requiring CPAP, BiPAP, or mechanical ventilation. BiPAP=bilevel or biphasic positive airway pressure. CPAP=continuous positive airway pressure. from baseline in length or height Z score was statistically significant at year 3 (p=0·0385) and year 4·5 (p=0·0346), but not at other timepoints. showed continued motor skill acquisition on the Median weight was 4·1 kg (range 2·1–9·2) at baseline PDMS-2 locomotion subtest (ie, increased age-equivalent (n=11) and 19·8 kg (range 15·1–31·4) at year 7 (n=7). scores; appendix). Among them, seven (88%) of Median weight Z scores increased to within 2 SD of the eight patients had standard scores more than 1 SD below mean for healthy age-matched and sex-matched peers the normal reference range (score <7) when they first at most timepoints from year 3 to year 7 (figure 4). The completed the assessment; five (63%) of eight patients mean increase from baseline in weight Z score was achieved scores within 1 SD of normal (figure 5B). statistically significant at year 3 (p=0·0096) and year 4·5 Eight (73%) of 11 patients transitioned to the BOT-2 (p=0·0074), but not at other time points. and completed at least one BOT-2 assessment Median head circumference was 41·5 cm (range (appendix). All had received asfotase alfa for a least 33·0–47·6) at baseline (n=11) and 50·5 cm (44·5–51·3) 5 years when first tested. Seven (88%) of eight patients at year 7 (n=7). Head circumference Z scores remained had initial scaled BOT-2 running speed and agility stable, with a median value of −1·01 (range −4·0 to 0·8) subtest scores more than 1 SD below normal (scaled at baseline (n=11) and −1·34 (−4·1 to 1·0) at last score <10; figure 5C). Three achieved normal scaled assessment (n=10; WHO criteria allow for calculation scores (≥10) by the end of the study. All six patients of head circumference Z scores for patients aged up to who completed serial BOT-2 assessments had improved 5 years). age-equivalent BOT-2 scores during treatment At baseline or first assessment, nine (82%) of 11 patients (appendix). had BSID-III gross motor scaled scores of 1 (3 SDs below Baseline serum ALP activity was low (median 21 U/L the normative mean). Nine (82%) of 11 patients had serial [range 9–46]) in the nine evaluable patients, and BSID-III assessments (two patients had one assessment increased by more than 100 times by day 2 after the each because of discontinuation and death; appendix). single intra­venous infusion of asfotase alfa (median All nine patients showed improvements in age-equivalent 2990 U/L [range 449–8007]; n=9), and remained elevated scores on the gross motor, fine motor, and cognitive thereafter with subcutaneous dosing (eg, 5304 U/L subscales (appendix). Median scaled gross motor scores [1812–10 085] at year 1 [n=8]18 and 4143 U/L [2267–6792] improved from 1 (range 1–8) at baseline to 6 (2–8) at at year 7 [n=7]). year 3 (normative mean 10, SD 3; figure 5A), indicating Baseline plasma concentrations of PPi were elevated motor skill improvement and less developmental delay. in four (50%) of eight evaluable patients (median Median scores on the fine motor and cognitive subscales 5·2 μM [range 2·9–10·5]; normal range for patients were low at baseline but normalised at year 2 and year 3 aged 0–12 years 1·33–5·71 μM; appendix). Median PPi (figure 5A). concen­trations decreased for all nine patients tested at Eight (73%) of 11 patients advanced to complete serial month 3 of treat­ment (2·6 μM [range 1·0–4·4]), and PDMS-2 assessments (appendix). All eight patients remained de­creased relative to baseline at other study www.thelancet.com/diabetes-endocrinology Vol 7 February 2019 99 Downloaded for Anonymous User (n/a) at President and Fellows of Harvard College on behalf of Harvard University from ClinicalKey.com by Elsevier on February 19, 2019. For personal use only. No other uses without permission. Copyright ©2019. Elsevier Inc. All rights reserved. Articles

2 Normal range 1

0

–1 *

–2 * Median Z score –3

–4 Length or height Weight –5 Baseline Month 6 Year 1 Year 2 Year 3 Year 4 Yera 5 Year 6 Year 7 (n=11) (n=10) (n=9) (n=9) (n=8) (n=6) (n=9) (n=9) (n=7) Duration of treatment Length or height Z score Median (range) −3·72 −3·62 −2·85 −2·67 −2·33 −2·21 −2·71 −2·47 −3·02 (−9·2 to −0·7) (−8·2 to −1·8) (−9·2 to −1·2) (−8·4 to −1·0) (−8·6 to −0·4) (−5·0 to +0·3) (−9·0 to +0·1) (−8·6 to −0·5) (−8·7 to −0·6) Change from +0·18 +0·62 +1·00 +1·69 +1·46 +1·24 +1·37 +0·55 baseline, mean (−0·60 to +0·97) (−0·27 to +1·52) (−0·43 to +2·42) (+0·12 to +3·25) (−1·98 to +4·90) (−0·79 to +3·26) (−0·44 to +3·18) (−1·62 to +2·73) (95% CI) Weight Z score Median (range) −3·84 −4·35 −3·30 −2·44 −1·23 −1·55 −1·21 −1·00 −0·99 (−5·4 to −0·5) (−6·4 to −1·5) (−6·3 to −1·7) (−4·8 to −0·9) (−5·1 to +0·4) (−3·6 to −0·8) (−5·0 to +0·2) (−5·6 to −0·1) (−3·7 to +0·5) Change from −0·53 +0·32 +1·03 +2·43 +1·27 +1·85 +2·02 +2·40 baseline, mean (−1·36 to +0·29) (−0·98 to +1·61) (−0·63 to +2·69) (+0·80 to +4·06) (−1·17 to +3·72) (−0·17 to +3·86) (−0·10 to +4·14) (−0·31 to +5·10) (95% CI)

Figure 4: Median length or height and weight Z scores over time in infants and young children with hypophosphatasia treated with asfotase alfa Shaded area is the normal range (mean ±2 SD) for healthy age-matched and sex-matched peers. *p<0·05 for comparison with baseline.

visits including year 7 (4·6 μM [2·1–10·2]; n=7), with adverse events were pyrexia, upper respiratory tract the exception of isolated fluctuations for individual infection, craniosyno­stosis, pneumonia, constipation, patients. otitis media, and vomiting. Most events were mild Baseline plasma concentrations of PLP were elevated (605 [76%] of 794 events) or moderate (151 [19%] of in all nine evaluable patients (median 421·0 ng/mL 794 events) in severity; eight (73%) of 11 patients had [range 100·0–880·0]; normal range for patients aged severe treatment-emergent adverse events (38 events; 0–5 years 11·8–68·4 ng/mL; appendix). Median PLP appendix). Most events were considered by investigators concentrations stayed within the normal range from to be unrelated to the study drug (664 [84%] of month 6 (47·6 ng/mL [16·4–1510·0]; n=10) to 794 events). Events assessed by investigators as possibly, year 7 (38·8 ng/mL [19·1–161·0]; n=7; normal range for probably, or definitely related to asfotase alfa in more patients aged 5–18 years 5·7–61·2 ng/mL). Only than two patients were injection-site erythema (n=4), one patient’s PLP concentrations failed to normalise at irritability (n=3), pyrexia (n=3), and vomiting (n=3). any time during the study (range 81·3–960 ng/mL); Ten (91%) of 11 patients had 79 serious treatment-emer­ this patient was not receiving vitamin B6 supple­ gent adverse events (appendix). Serious events that mentation. Overall, the data appeared similar when were considered by the investigator to be related to patients receiving vitamin B6 supplementation were asfotase alfa were severe chronic hepatitis (n=1; this excluded from the analysis (data not shown). event occurred concurrently with use of montelukast Serum concentrations of parathyroid hormone over and resolved upon discontinuation of montelukast), the course of treatment are shown in the appendix. moderate immediate post-injection reaction­ (IAR, As previously published,18 one patient withdrew including abdominal pain, skin erythema, dizziness, because of adverse events during the initial intravenous headache, and chills; n=1), and severe craniosynostosis­ infusion of asfotase alfa and one patient died from with severe conductive deafness (n=1). sepsis at around age 8 months, after 7·5 months of Four patients had a total of ten adverse events con­ therapy. No additional deaths or discontinuations sidered by the investigators as possibly reflecting occurred. All 11 patients had at least one treatment- hyper­sensitivity, and were therefore designated IARs. emergent adverse event. The table summarises the Most (eight [80%] of ten adverse events) occurred on treatment-emergent adverse events occurring in more day 1 in conjunction with the initial intravenous than 25% of patients, regardless of association with infusion. The only IAR reported for more than one asfotase alfa. The most common treatment-emergent patient was pyrexia (n=3). All IARs were mild or

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moderate in severity; none were life-threatening. The A one patient who with­drew from the study had IARs of 9·5 10 piloerection, pyrexia, and chills during the intravenous Normal range (7–11) 9·0 (8–10) 9 infusion. Blood complement testing was done in 8·0 (7–11) two patients with IARs; neither had a clinically 8 significant result. 7·0 7·0 (6–10) (7–13) 7 Seven (64%) of 11 patients had 78 ISRs; the majority 6·0 6·0 6·0 Gross motor (1–10) 5·5 (3–11) (2–8) (47 [60%] of 78 events) occurred in two patients. No 6 Fine motor 5·0 (1–13) 5·0 Cognitive severe or serious ISRs were reported. One patient had (1–10) (1–7) 5 treatment-emergent adverse events of injection site 4·0 (1–13) calcifications observed radiographically in the soft 4 3·0 tissue lateral to the left and right hip joints, after (1–8) 3 receiving asfotase alfa injections deeply and repeatedly 2·0

Median (range) BSID-III scaled score (1–5) 2 in that location for approximately 1 year (dosage at the 1·0 1·0 1·0 1·0 time of the adverse event was 2 mg/kg three times per (1–8) (1–9) (1–4) (1–1) 1 week). The calcifications were considered to be possibly drug related, treated by rotating the injection sites, and 0 Baseline Month 3 Month 6 Year 1 Year 2 (n=6; Year 3 resolved by the end of the study. Three patients (n=5) (n=9) (n=10) (n=7) cognitive, n=5) (n=3) had treatment-emergent adverse events related to Duration of treatment lipohypertrophy, all were mild or moderate in severity, B occurring after at least 2 years of treatment, and 14 ongoing at study end. 13 Two patients had treatment-emergent adverse events of Normal range 12 seizures during treatment; one had pyridoxine-dependent seizures before and during the study. Six patients had 11 fractures during the study; all but one patient had a 10 history of fractures before the study. Seven patients had 13 craniosynostosis-related events that were all moderate 9 or severe and, in all but one patient, were considered 8 unrelated to asfotase alfa treatment. Four patients underwent surgery for craniosynostosis. 7 One patient developed mild treatment-emergent 6 adverse events of ectopic calcifications in the conjunctiva approximately 6·5 years after starting 5 treatment; no action was taken. The ectopic 4 calcifications were considered to be possibly related to PDMS-2 locomotion subscale standard score asfotase alfa treatment and were ongoing at study end. 3 Two patients had treatment-emergent adverse events of 2 nephro­calcinosis, observed when the asfotase alfa Patient 1 (8·3 months) Patient 7 (1·3 months) Patient 10 (2·9 months) 1 Patient 2 (6·9 months) Patient 8 (33·3 months) Patient 11 (5·3 months) dosage was 2 mg/kg three times per week. The first Patient 5 (39·5 months) Patient 9 (7·4 months) patient had a history of bilateral nephrocalcinosis at 0 baseline, and the treatment-emergent adverse event Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 was first documented at the first renal ultrasound at C 20 Normal range

15 Figure 5: Motor and cognitive function over time in infants and young children with hypophosphatasia treated with asfotase alfa (A) Scaled median (range) BSID-III gross motor, fine motor, and cognitive subscale scores. The BSID-III was applied for patients younger than 10 43 months. Assessments were done on the basis of the patient’s chronological Patient 1 (8·3 months) age and functional abilities. Shaded area is the mean (SD) scaled score for Patient 2 (6·9 months) healthy age-matched peers. Stability in scaled scores over time indicates Patient 5 (39·5 months) Patient 7 (1·3 months) continued acquisition or improvement in quality of motor skills. (B) PDMS-2 5 Patient 8 (33·3 months) locomotion subscale standard scores for each individual patient (months Patient 9 (7·4 months) indicate age at study entry). (C) BOT-2 running speed and agility scaled scores Patient 10 (2·9 months) BOT-2 running speed and agility scaled score for each individual patient (months indicate age at study entry). Patient 11 (5·3 months) 0 BOT-2=Bruininks-Oseretsky Test of Motor Proficiency, second edition. Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 BSID-III=Bayley Scales of Infant and Toddler Development, third edition. Duration of treatment PDMS-2=Peabody Developmental Motor Scales, second edition. www.thelancet.com/diabetes-endocrinology Vol 7 February 2019 101 Downloaded for Anonymous User (n/a) at President and Fellows of Harvard College on behalf of Harvard University from ClinicalKey.com by Elsevier on February 19, 2019. For personal use only. No other uses without permission. Copyright ©2019. Elsevier Inc. All rights reserved. Articles

Serum concentrations of calcium and phosphate over Patients treated with asfotase alfa (n=11) the course of treatment are shown in the appendix. Eight (80%) of ten evaluable patients tested positive Pyrexia 8 (73%) for asfotase alfa antibodies (maximum titre 2048) over Upper respiratory tract infection 8 (73%) the course of treatment; five (50%) of ten patients Craniosynostosis 7 (64%) tested positive for neutralising antibodies. No dosage Pneumonia 7 (64%) adjust­ments were made on the basis of the presence Constipation 6 (55%) of antibodies, and the antibodies had no apparent Otitis media 6 (55%) effect on pharmacodynamic outcomes, improvements Vomiting 6 (55%) in skel­etal manifestations, or other outcome measures Headache 5 (46%) (data not shown). Injection site erythema 5 (46%) Decreased haemoglobin 4 (36%) Discussion Dental caries 4 (36%) In this Article we report the long-term (up to 7 year) Diarrhoea 4 (36%) safety and efficacy of asfotase alfa treatment for Irritability 4 (36%) paediatric patients with life-threatening hypophospha­ Nasopharyngitis 4 (36%) tasia. Although mortality historically has been high in Pain 4 (36%) patients with perinatal and infantile hypophosphatasia, Pain in extremity 4 (36%) most of the 11 individuals in our study who began Rash 4 (36%) therapy as infants or young children showed rapid and Tooth loss 4 (36%) substantial improvements in skeletal mineralisation Viral infection 4 (36%) and then respiratory, motor, and cognitive function Acute sinusitis 3 (27%) documented at 1 year of treatment with asfotase alfa.18 Allergic rhinitis 3 (27%) These improve­ments persisted over 7 years of therapy. Decreased oxygen saturation 3 (27%) Pharmacodynamic results showed that decreases in Drug dependence 3 (27%) the plasma concentrations of TNSALP substrates Gastroenteritis 3 (27%) (ie, PPi and PLP) that were achieved after 6 months of 18 Increased urine calcium:creatinine ratio 3 (27%) treatment persisted throughout the study, except for Influenza 3 (27%) transient elevations in median PLP concentrations. Injection site haematoma 3 (27%) Moreover, plasma concentrations of PPi following Nausea 3 (27%) treatment with asfotase alfa were above or near the Papilloedema 3 (27%) lower limit of normal, and did not decrease to Pharyngitis 3 (27%) subnormal concentrations. Low PPi has been associated Procedural pain 3 (27%) with increased risk of vascular and other forms of Respiratory distress 3 (27%) ectopic calcification in animal models and certain 28–30 Sinusitis 3 (27%) patient populations. Sleep apnoea syndrome 3 (27%) Radiographic assessments of hypophosphatasia Tracheitis 3 (27%) skeletal disease, made using two validated scales (RGI-C20 and RSS21), supported improvement in all Wheezing 3 (27%) evaluable patients as early as month 6 of treatment.18 Data are presented as number of patients (%). These patients had severe rickets at baseline, with a

Table: Treatment-emergent adverse events reported for more than 25% of median RSS of 8·3. After 4 years of treatment, this patients with hypophosphatasia treated with asfotase alfa score was reduced to a median RSS score of 0·5, which represents near absence of metaphyseal cupping or fraying. On the RGI-C scale, which provides a broader week 48. No action was taken, and the event was assessment of the skeletal features of paediatric ongoing at study end. The second patient had no history hypophosphatasia than does the RSS score, scores of at of nephrocalcinosis at baseline, but a questionable least +2, indicating substantial healing, were reached calcium deposit was reported in the first renal during 6 months of treatment and were sustained ultrasound at month 6. Nephrocalcinosis was first through year 7. With longer treatment, these still reported as a treatment-emergent adverse event at prepubertal children might have further skeletal approximately year 3. The patient was treated with oral healing. potassium citrate two times per day for 3 months. Further, the skeletal improvements were associated Subsequent renal ultrasounds indicated small calcium with sustained improvements in respiratory status. deposits at year 4·5, year 5, and year 5·5 that did not Although none of nine patients required respiratory meet the criteria for nephrocalcinosis and that were support from year 4 through to study end, we note that gone from year 6 through to study end. several participants required prolonged support as

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babies or young children to achieve this outcome sitting, and walking), fine motor (eg, manipulating (figure 3). An expanded cohort of 39 paediatric patients blocks, holding a cup, and cutting with scissors), and with perinatal or infantile hypophosphatasia that cognitive (eg, discriminating and classifying objects) included the patients enrolled in this study (n=11) and subscales. Most patients also showed increases in another multicentre, multinational, open-label study in scaled scores, indicating catch up to healthy peers (n=28; age ≤5 years) has been assessed for respiratory in acquisition of new motor and cognitive skills. function and survival during treatment with asfotase Eight patients completed skills assessed by the BSID-III alfa (median duration 2·7 years).15 These 39 treated and then advanced to the PDMS-2 locomotion subtest, patients were compared with 48 untreated historical which evaluates tasks such as jumping, climbing stairs, control patients of similar age with regard to running, and skipping. Eight children further advanced hypophosphatasia characteristics. Among the 39 treated to the BOT-2 running speed and agility subtest, which patients, 21 (54%) required ventilator support; in itself reflects the development of skills typical of 14 (36%) at baseline and an additional seven (18%) soon school-age children (eg, shuttle running and hopping). after initiation of therapy.15 Among the 48 historical Previously, we reported significant improvements for controls, 20 (42%) required some form of respiratory children aged 6–12 years at baseline (n=13) with severe support. Kaplan-Meier-estimated survival at 5 years was hypophosphatasia in growth (p≤0·0088) and motor signifi­cantly better for the treated patients (82%) than function (p≤0·01) over 5 years of asfotase alfa treatment the historical controls (27%; p<0·0001).15 Among the during a phase 2, open-label study and its extension.32 21 treated patients ever requiring respiratory support, Asfotase alfa continued to be generally well tolerated 16 (76%) survived and 12 (57%) were weaned from in this study. No deaths or safety-related discontinuations respiratory support. Improved skeletal mineralisation­ of therapy occurred after the one death and one study in treated patients was associated with improved withdrawal discussed in our publication in 2012.18 respiratory status, and RGI-C scores of at least +2 The most common treatment-emergent adverse events (substantial or near-complete or complete healing) gen­er­ally reflected typical signs, symptoms, or com­ were achieved by all patients who were weaned from plications of hypophosphatasia, and infections that respiratory support.15 The results of our study are also commonly occur in healthy young children. Ophthal­ consistent with those of an open-label study by Kitaoka mological exami­nations, renal ultrasound, and anti- and colleagues in 2017,31 who reported improved asfotase alfa antibody testing revealed no additional survival, skeletal mineralisation, and respiratory status substantial issues associated with this treatment. Seven in 13 Japanese patients with hypophosphatasia (median patients had 13 craniosynostosis-related events. These age at baseline 91 days, range 0 days to 34 years) treated events were not unexpected, given that craniosynostosis with asfotase alfa.31 is a common complication of hypophosphatasia,11 and Long-term evaluation of the current cohort of nine would not be expected to reverse with asfotase alfa treated children provided evidence of catch-up growth treatment. In a natural history study of patients with in some patients. Improvements were observed as early severe perinatal and infantile hypophosphatasia, the as month 6 in median length or height Z scores and reported incidence of craniosynostosis was 61%.33 year 1 in median weight Z scores. Median weight Monitoring guidance for patients with hypophospha­ Z scores were normalised from year 3 to the end of the tasia receiving treatment with asfotase alfa was study, whereas median length or height Z scores published in 2017 by Kishnani and colleagues.34 Briefly, generally improved but remained below normal recom­mendations for safety monitoring include ISRs throughout the study. Approximately half of the patients and any hypersensitivity reactions and lipodystrophy,­ had cranio­synostosis requiring surgery, and two and events of special interest that in severely affected patients were found to have scoliosis (appendix), which patients can include hypercalcaemia or hypo­calcaemia, probably lowered their length or height Z scores. cranio­syno­stosis, ectopic calcifications of the con­ BSID-III assessments indicated profound develop­ junctiva, and nephrocalcinosis.­ Injection-site lipo­ mental delays at baseline. Gross motor impairment hypertrophy and atrophy can be prevented or minimised exceeded fine motor impairment. ognitiveC scores were by rotating injection sites among the abdominal, low at baseline and increased rapidly. However, as deltoid, and thigh areas.34 Although patients who are BSID-III cognitive assessment depends on motor severely affected by hypophosphatasia might have stability in the trunk, head control, visual ability, and hypercalcaemia,18 improvements­ in skeletal mineral­ ability to manipulate toys, scores might have been isation can require an increase in calcium intake upon artificially low and improved when the children were initiation of asfotase alfa treatment (ie, hungry bone able to sit independently, emphasising the importance syndrome). Therefore, serum calcium and parathyroid of increased strength and bone stability for gross motor hormone must be monitored in such patients, and and global development. All nine treated patients had additional calcium should be provided as needed. substantial improvements in age-equivalent scores on Our study had several limitations; understandably, it was the BSID-III gross motor (eg, head control, rolling, uncontrolled, because life-threatening hypophospha­tasia www.thelancet.com/diabetes-endocrinology Vol 7 February 2019 103 Downloaded for Anonymous User (n/a) at President and Fellows of Harvard College on behalf of Harvard University from ClinicalKey.com by Elsevier on February 19, 2019. For personal use only. No other uses without permission. Copyright ©2019. Elsevier Inc. All rights reserved. Articles

was present, and it involved only a small number of 2 Weiss MJ, Cole DE, Ray K, et al. A missense mutation in the patients manifesting the most severe forms of this rare human liver/bone/kidney alkaline phosphatase gene causing a lethal form of hypophosphatasia. Proc Natl Acad Sci USA 1988; 85: 7666–69. genetic metabolic disorder. However, the improved 3 Whyte MP. Physiological role of alkaline phosphatase explored in survival documented in this Article for perinatal or hypophosphatasia. Ann NY Acad Sci 2010; 1192: 190–200. infantile hypophosphatasia treated with asfotase alfa was 4 Whyte MP, Mahuren JD, Vrabel LA, Coburn SP. Markedly increased circulating pyridoxal-5’-phosphate levels in hypophosphatasia. consistent with that found in a subsequent investigation of Alkaline phosphatase acts in vitamin B6 metabolism. a larger cohort of similarly treated patients that included a J Clin Invest 1985; 76: 752–56. matched historical control group.15 Furthermore,­ motor 5 Russell RGG. Excretion of inorganic pyrophosphate in and cognitive function were assessed in our study using hypophosphatasia. Lancet 1965; 286: 461–64. 6 Fleisch H, Russell RG, Straumann F. Effect of pyrophosphate on different instruments,sometimes sequentially,­ on the hydroxyapatite and its implications in calcium homeostasis. basis of the patient’s age, functional capability, and physical Nature 1966; 212: 901–33. status. Lastly, age-equivalent or standard scores might not 7 Whyte MP. Hypophosphatasia and how alkaline phosphatase promotes mineralization. In: Thakker RV, Whyte MP, Eisman J, always capture functional improvements observed through Igarashi T, eds. Genetics of bone biology and skeletal disease. increases in raw point scores. 2nd edn. San Diego: Elsevier (Academic Press), 2018: 481–504. To summarise, infants and young children with life- 8 Baumgartner-Sigl S, Haberlandt E, Mumm S, et al. Pyridoxine-responsive seizures as the first symptom of infantile threatening perinatal or infantile hypophosphatasia treated hypophosphatasia caused by two novel missense mutations with asfotase alfa before or at age 3 years showed sub­ (c.677T>C, p.M226T; c.1112C>T, p.T371I) of the tissue-nonspecific stantial early improvements in skeletal mineral­isation and alkaline phosphatase gene. Bone 2007; 40: 1655–61. 9 Balasubramaniam S, Bowling F, Carpenter K, et al. Perinatal respiratory function, followed by improved weight and hypophosphatasia presenting as neonatal epileptic encephalopathy motor and cognitive function, all sustained up to 7 years of with abnormal neurotransmitter metabolism secondary to reduced treatment. Asfotase alfa was generally well tolerated. co-factor pyridoxal-5ʹ-phosphate availability. J Inherit Metab Dis 2010; 33 (suppl 3): S25–33. Contributors 10 Kozlowski K, Sutcliffe J, Barylak A, et al. Hypophosphatasia. MPW, DP, KPF, and SM helped design the study. MM, JT, JHS, NJS, Review of 24 cases. Pediatr Radiol 1976; 5: 103–17. and NB served as study investigators. MM, JT, JHS, NJS, and SM collected 11 Collmann H, Mornet E, Gattenlohner S, Beck C, Girschick H. and assembled the data. SM analysed the data. All authors were involved Neurosurgical aspects of childhood hypophosphatasia. in the data interpretation. MPW advanced the manuscript, coordinating Childs Nerv Syst 2009; 25: 217–23. the reviews and providing oversight on all revisions. WHM reviewed and 12 Silver MM, Vilos GA, Milne KJ. Pulmonary hypoplasia in neonatal selected all the radiographs for publication. All authors contributed to the hypophosphatasia. Pediatr Pathol 1988; 8: 483–93. review and revisions of the manuscript and approved the final version. 13 Leung EC, Mhanni AA, Reed M, Whyte MP, Landy H, Greenberg CR. Declaration of interests Outcome of perinatal hypophosphatasia in Manitoba Mennonites: a retrospective cohort analysis. JIMD Rep 2013; 11: 73–78. MPW was the principal clinical study investigator and received honoraria, 14 Nakamura-Utsunomiya A, Okada S, Hara K, et al. Clinical travel support, and research grants from Alexion Pharmaceuticals. characteristics of perinatal lethal hypophosphatasia: a report of JHS was a clinical study investigator and received honoraria and travel 6 cases. Clin Pediatr Endocrinol 2010; 19: 7–13. support from Alexion Pharmaceuticals. SM and KPF are employees of 15 Whyte MP, Rockman-Greenberg C, Ozono K, et al. Asfotase alfa and might own stock options in Alexion Pharmaceuticals. NB was a treatment improves survival for perinatal and infantile clinical study investigator and received grant and research support from hypophosphatasia. J Clin Endocrinol Metab 2016; 101: 334–42. Alexion Pharmaceuticals. NJS was a clinical study investigator, and 16 European Medicines Agency. Strensiq (asfotase alfa). Jan 29, 2016. received research support from Alexion Pharmaceuticals, through a https://www.ema.europa.eu/en/medicines/human/EPAR/strensiq hospital agreement. JT was a clinical study investigator and an employee (accessed March 27, 2017). of Prevea Health Clinic, which at the time of the study was owned by 17 Strensiq. Package insert. Boston: Alexion Pharmaceuticals, 2018. Hospital Sisters Health System St Vincent Hospital, which received grant 18 Whyte MP, Greenberg CR, Salman NJ, et al. Enzyme-replacement and research support from Alexion Pharmaceuticals. DP was a therapy in life-threatening hypophosphatasia. N Engl J Med 2012; consultant for Alexion Pharmaceuticals at the time of the study, 366: 904–13. and received funding and travel support from Alexion Pharmaceuticals 19 Rodriguez E, Bober MB, Davey L, et al. Respiratory mechanics in an for consulting and participating on advisory boards. MM was a clinical infant with perinatal lethal hypophosphatasia treated with human study investigator and received honoraria and travel support from recombinant enzyme replacement therapy. Pediatr Pulmonol 2012; Alexion Pharmaceuticals. WHM declares no competing interests. 47: 917–22. Editorial and writing support was provided by Lela Creutz and 20 Whyte MP, Fujita KP, Moseley S, Thompson DD, McAlister WH. Bina J Patel of Peloton Advantage, funded by Alexion Pharmaceuticals. Validation of a novel scoring system for changes in skeletal All authors had full access to all the data in the study and take manifestations of hypophosphatasia in newborns, infants, and responsibility for the integrity of the data and the accuracy of the data children: the Radiographic Global Impression of Change scale. analysis. J Bone Miner Res 2018; 33: 868–74. 21 Thacher TD, Fischer PR, Pettifor JM, Lawson JO, Manaster BJ, Acknowledgments Reading JC. Radiographic scoring method for the assessment of the We thank the patients and their families for their participation in this severity of nutritional rickets. J Trop Pediatr 2000; 46: 132–39. study, and all the health-care professionals who treated these patients. 22 Kuczmarski RJ, Ogden CL, Guo SS, et al. 2000 CDC growth charts We are grateful to Vinieth Bijanki, of Shriners Hospital for Children for the United States: methods and development. (St Louis, MO, USA), for his review and assembly of the radiographic Vital Health Stat 11 2002; 246: 1–190. images, and to Mary Kunjappu, of Alexion Pharmaceuticals, for her 23 WHO. WHO child growth standards: head circumference-for-age, assistance in the development of the manuscript. This study was arm circumference-for-age, triceps skinfold-for-age and subscapular sponsored by Alexion Pharmaceuticals. skinfold-for-age: methods and development. 2007. http://www.who. int/childgrowth/standards/second_set/technical_report_2.pdf?ua=1 References (accessed July 31, 2018). 1 Whyte MP. Hypophosphatasia—aetiology, nosology, pathogenesis, 24 Bayley N. Bayley Scales of Infant and Toddler Development. diagnosis and treatment. Nat Rev Endocrinol 2016; 12: 233–46. Administration manual, 3rd ed. San Antonio: Pearson, 2006.

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