Browsing by Author "Chen, Chao-Yin"

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    Burosumab Therapy in Children with X-Linked Hypophosphatemia
    (Massachusetts Medical Society, 2018-05) Carpenter, Thomas O.; Whyte, Michael P.; Imel, Erik A.; Boot, Annemieke M.; Högler, Wolfgang; Linglart, Agnès; Padidela, Raja; van't Hoff, William; Mao, Meng; Chen, Chao-Yin; Skrinar, Alison; Kakkis, Emil; San Martin, Javier; Portale, Anthony A.; Medicine, School of Medicine
    BACKGROUND X-linked hypophosphatemia is characterized by increased secretion of fibroblast growth factor 23 (FGF-23), which leads to hypophosphatemia and consequently rickets, osteomalacia, and skeletal deformities. We investigated burosumab, a monoclonal antibody that targets FGF-23, in patients with X-linked hypophosphatemia. METHODS In an open-label, phase 2 trial, we randomly assigned 52 children with X-linked hypophosphatemia, in a 1:1 ratio, to receive subcutaneous burosumab either every 2 weeks or every 4 weeks; the dose was adjusted to achieve a serum phosphorus level at the low end of the normal range. The primary end point was the change from baseline to weeks 40 and 64 in the Thacher rickets severity total score (ranging from 0 to 10, with higher scores indicating greater disease severity). In addition, the Radiographic Global Impression of Change was used to evaluate rachitic changes from baseline to week 40 and to week 64. Additional end points were changes in pharmacodynamic markers, linear growth, physical ability, and patient-reported outcomes and the incidence of adverse events. RESULTS The mean Thacher rickets severity total score decreased from 1.9 at baseline to 0.8 at week 40 with every-2-week dosing and from 1.7 at baseline to 1.1 at week 40 with every-4-week dosing (P<0.001 for both comparisons); these improvements persisted at week 64. The mean serum phosphorus level increased after the first dose in both groups, and more than half the patients in both groups had levels within the normal range (3.2 to 6.1 mg per deciliter [1.0 to 2.0 mmol per liter]) by week 6. Stable serum phosphorus levels were maintained through week 64 with every-2-week dosing. Renal tubular phosphate reabsorption increased from baseline in both groups, with an overall mean increase of 0.98 mg per deciliter (0.32 mmol per liter). The mean dose of burosumab at week 40 was 0.98 mg per kilogram of body weight with every-2-week dosing and 1.50 mg per kilogram with every-4-week dosing. Across both groups, the mean serum alkaline phosphatase level decreased from 459 U per liter at baseline to 369 U per liter at week 64. The mean standing-height z score increased in both groups, with greater improvement seen at all time points with every-2-week dosing (an increase from baseline of 0.19 at week 64) than with every-4-week dosing (an increase from baseline of 0.12 at week 64). Physical ability improved and pain decreased. Nearly all the adverse events were mild or moderate in severity. CONCLUSIONS In children with X-linked hypophosphatemia, treatment with burosumab improved renal tubular phosphate reabsorption, serum phosphorus levels, linear growth, and physical function and reduced pain and the severity of rickets.
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    Burosumab versus conventional therapy in children with X-linked hypophosphataemia: a randomised, active-controlled, open-label, phase 3 trial
    (Elsevier, 2019-06-15) Imel, Erik A.; Glorieux, Francis H.; Whyte, Michael P.; Munns, Craig F.; Ward, Leanne M.; Nilsson, Ola; Simmons, Jill H.; Padidela, Raja; Namba, Noriyuki; Cheong, Hae Il; Pitukcheewanont, Pisit; Sochett, Etienne; Högler, Wolfgang; Muroya, Koji; Tanaka, Hiroyuki; Gottesman, Gary S.; Biggin, Andrew; Perwad, Farzana; Mao, Meng; Chen, Chao-Yin; Skrinar, Alison; Martin, Javier San; Portale, Anthony A.; Medicine, School of Medicine
    Background X-linked hypophosphatemia in children is characterized by elevated serum FGF23, hypophosphatemia, rickets, lower extremity bowing, and growth impairment. We compared the efficacy and safety of continuing conventional therapy, consisting of oral phosphate and active vitamin D, versus switching to burosumab, a fully human monoclonal antibody against FGF23, in pediatric X-linked hypophosphatemia. Methods In this randomised, active-controlled, open-label, phase 3 trial at 16 clinical sites, we enrolled children with X-linked hypophosphataemia aged 1–12 years. Key eligibility criteria were a total Thacher rickets severity score of at least 2·0, fasting serum phosphorus lower than 0·97 mmol/L (3·0 mg/dL), confirmed PHEX (phosphate-regulating endopeptidase homolog, X-linked) mutation or variant of unknown significance in the patient or a family member with appropriate X-linked dominant inheritance, and receipt of conventional therapy for at least 6 consecutive months for children younger than 3 years or at least 12 consecutive months for children older than 3 years. Eligible patients were randomly assigned (1:1) to receive either subcutaneous burosumab starting at 0·8 mg/kg every 2 weeks (burosumab group) or conventional therapy prescribed by investigators (conventional therapy group). Both interventions lasted 64 weeks. The primary endpoint was change in rickets severity at week 40, assessed by the Radiographic Global Impression of Change global score. All patients who received at least one dose of treatment were included in the primary and safety analyses. The trial is registered with ClinicalTrials.gov, number NCT02915705. Findings Recruitment took place between Aug 3, 2016, and May 8, 2017. Of 122 patients assessed, 61 were enrolled. Of these, 32 (18 girls, 14 boys) were randomly assigned to continue receiving conventional therapy and 29 (16 girls, 13 boys) to receive burosumab. For the primary endpoint at week 40, patients in the burosumab group had significantly greater improvement in Radiographic Global Impression of Change global score than did patients in the conventional therapy group (least squares mean +1·9 [SE 0·1] with burosumab vs +0·8 [0·1] with conventional therapy; difference 1·1, 95% CI 0·8–1·5; p<0·0001). Treatment-emergent adverse events considered possibly, probably, or definitely related to treatment by the investigator occurred more frequently with burosumab (17 [59%] of 29 patients in the burosumab group vs seven [22%] of 32 patients in the conventional therapy group). Three serious adverse events occurred in each group, all considered unrelated to treatment and resolved. Interpretation Significantly greater clinical improvements were shown in rickets severity, growth, and biochemistries among children with X-linked hypophosphataemia treated with burosumab compared with those continuing conventional therapy. Funding Ultragenyx Pharmaceutical Inc. and Kyowa Kirin International
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    OR13-2 Burosumab Resulted in Greater Improvement in Rickets Than Conventional Therapy in Children with X-Linked Hypophosphatemia (XLH)
    (Oxford University Press, 2019-04-15) Imel, Erik; Whyte, Michael; Munns, Craig; Portale, Anthony; Ward, Leanne; Nilsson, Ola; Simmons, Jill; Padidela, Raja; Namba, Noriyuki; Cheong, Hae Il; Mao, Meng; Chen, Chao-Yin; Skrinar, Alison; San Martin, Javier; Glorieux, Francis; Medicine, School of Medicine
    XLH is characterized by excess FGF23, hypophosphatemia, skeletal deformities, and growth impairment. For the last 40 years, XLH has been treated with multiple daily doses of oral phosphate and active vitamin D (Pi/D). Burosumab, a fully human monoclonal antibody to FGF23, has been approved by the FDA for the treatment of XLH in patients ≥1 year-old. In this Phase 3 trial (NCT02915705), 61 children with XLH (1-12 years old) were randomized (1:1) to receive subcutaneous burosumab starting at 0.8 mg/kg every 2 weeks or continue Pi/D titrated and individualized for each subject by investigators. Eligibility criteria included a Total Rickets Severity Score (RSS) ≥2.0 despite prior treatment with Pi/D (>7-day washout before baseline). The primary endpoint was healing of rickets at Week 40 assessed by radiologists blinded to treatment using the Radiographic Global Impression of Change (RGI-C). The mean ± SE daily oral phosphate dose from baseline to Week 40 was 37.8 ± 3.2 mg/kg, with >99% compliance reported based on days of dosing. Compared with Pi/D, 40 weeks of burosumab resulted in a greater LS mean ± SE increase in serum phosphorus (0.92 ± 0.08 vs 0.20 ± 0.06 mg/dL), TmP/GFR (1.19 ± 0.11 vs -0.16 ± 0.05 mg/dL), and 1,25(OH)2D (30 ± 4 vs 19 ± 4 pg/mL). At Week 40, rickets improved in both groups; RGI-C global score was significantly higher in burosumab subjects than in Pi/D subjects (LS mean ± SE: +1.9 ± 0.1 vs +0.8 ± 0.1; p<0.0001). More burosumab subjects had substantial healing (RGI-C ≥+2.0), compared with Pi/D subjects (21/29, 72% vs 2/32, 6%; odds ratio of 39.1, p<0.0001). Improvement in the RGI-C lower limb deformity score was greater with burosumab than with Pi/D (+0.62 ± 0.12 vs +0.21 ± 0.12; p=0.02). Alkaline phosphatase decreased more with burosumab compared with Pi/D (-131 ± 13 vs 35 ± 19; p<0.0001). Consistent with decreases in rickets severity, burosumab improved growth and mobility. Standing height Z-score increased by a LS mean change (95% CI) of +0.15 (0.05, 0.25) for burosumab and +0.08 (-0.02, 0.19) for Pi/D. The 6 Minute Walk Test percent predicted distance increased with burosumab (Baseline to Week 40: 62% to 72%) and was unchanged with Pi/D (76% to 75%). Nephrocalcinosis score (range 0-4) shifted 0 in 20 Pi/D and 24 burosumab subjects; +1 in 3 Pi/D and 0 burosumab subjects; and -1 in 3 Pi/D and 2 burosumab subjects. Pre-defined adverse events (AEs) of interest, including hypersensitivity and injection site reactions, were higher in the burosumab group and were mild to moderate in severity overall. There were 4 serious AEs (3 burosumab, 1 Pi/D); none were treatment-related and all resolved. No subject discontinued study drug in either group. Data after 64 weeks of treatment will be available at the time of presentation. In this randomized Phase 3 trial, burosumab resulted in increases in growth and mobility, and significantly greater improvements in rickets than Pi/D in 1-12 year-old children with XLH.
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    A Randomized, Double-Blind, Placebo-Controlled, Phase 3 Trial Evaluating the Efficacy of Burosumab, an Anti-FGF23 Antibody, in Adults With X-Linked Hypophosphatemia: Week 24 Primary Analysis
    (Wiley, 2018-08) Insogna, Karl L.; Briot, Karine; Imel, Erik A.; Kamenický, Peter; Ruppe, Mary D.; Portale, Anthony A.; Weber, Thomas; Pitukcheewanont, Pisit; Cheong, Hae Il; Jan de Beur, Suzanne; Imanishi, Yasuo; Ito, Nobuaki; Lachmann, Robin H.; Tanaka, Hiroyuki; Perwad, Farzana; Zhang, Lin; Chen, Chao-Yin; Theodore-Oklota, Christina; Mealiffe, Matt; San Martin, Javier; Carpenter, Thomas O.; Pediatrics, School of Medicine
    In X-linked hypophosphatemia (XLH), inherited loss-of-function mutations in the PHEX gene cause excess circulating levels of fibroblast growth factor 23 (FGF23), leading to lifelong renal phosphate wasting and hypophosphatemia. Adults with XLH present with chronic musculoskeletal pain and stiffness, short stature, lower limb deformities, fractures, and pseudofractures due to osteomalacia, accelerated osteoarthritis, dental abscesses, and enthesopathy. Burosumab, a fully human monoclonal antibody, binds and inhibits FGF23 to correct hypophosphatemia. This report summarizes results from a double-blind, placebo-controlled, phase 3 trial of burosumab in symptomatic adults with XLH. Participants with hypophosphatemia and pain were assigned 1:1 to burosumab 1 mg/kg (n = 68) or placebo (n = 66) subcutaneously every 4 weeks (Q4W) and were comparable at baseline. Across midpoints of dosing intervals, 94.1% of burosumab-treated participants attained mean serum phosphate concentration above the lower limit of normal compared with 7.6% of those receiving placebo (p < 0.001). Burosumab significantly reduced the Western Ontario and the McMaster Universities Osteoarthritis Index (WOMAC) stiffness subscale compared with placebo (least squares [LS] mean ± standard error [SE] difference, -8.1 ± 3.24; p = 0.012). Reductions in WOMAC physical function subscale (-4.9 ± 2.48; p = 0.048) and Brief Pain Inventory worst pain (-0.5 ± 0.28; p = 0.092) did not achieve statistical significance after Hochberg multiplicity adjustment. At week 24, 43.1% (burosumab) and 7.7% (placebo) of baseline active fractures were fully healed; the odds of healed fracture in the burosumab group was 16.8-fold greater than that in the placebo group (p < 0.001). Biochemical markers of bone formation and resorption increased significantly from baseline with burosumab treatment compared with placebo. The safety profile of burosumab was similar to placebo. There were no treatment-related serious adverse events or meaningful changes from baseline in serum or urine calcium, intact parathyroid hormone, or nephrocalcinosis. These data support the conclusion that burosumab is a novel therapeutic addressing an important medical need in adults with XLH.© 2018 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals, Inc.