ESPE Abstracts

Background: Hypophosphatasia (HPP) is the rare inherited metabolic disorder resulting from loss-of-function mutation(s) in the tissue-nonspecific alkaline phosphatase (TNSALP) gene. TNSALP deficiency can cause a spectrum of complications in children including premature deciduous tooth loss, rickets, poor growth, and compromised physical function. We previously reported that children, 5–12 years old, with HPP and treated with asfotase alfa, a recombinant bone-targeted huma...

In XLH, excess fibroblast growth factor 23 (FGF23) causes hypophosphatemia and consequent rickets, skeletal deformities, and growth impairment. The efficacy and safety of burosumab, a fully human monoclonal antibody against FGF23, was evaluated in two Phase 2 trials in children with XLH. In CL201, 52 children with XLH (5–12 years old, Tanner ≤2) were randomized 1:1 to receive subcutaneous burosumab every 2 (Q2W) or 4 (Q4W) weeks, with doses titrated up to 2 mg/kg to...

In children with XLH, excess FGF23 causes hypophosphatemia with consequent rickets, skeletal deformities, and impaired growth and mobility. We previously reported that burosumab improved phosphate homeostasis and rickets in children with XLH. Here, we report final data from this Phase 2 Study CL201 (NCT02163577).Fifty-two children with XLH (5-12 years old, Tanner ≤ 2) were randomized 1:1 to receive subcutaneous burosumab every 2 (Q2W) or 4 (Q4W) we...

In children with XLH, excess FGF23 causes hypophosphatemia with consequent rickets, skeletal deformities, and impaired growth and mobility. We reported that burosumab improved phosphate homeostasis and rickets in children with XLH. Here, we present data on 11/52 subjects (all girls) who developed fused growth plates during the phase 2 study CL201 (NCT02163577).In CL201, 52 subjects (Baseline: 5-12 years-old, Tanner ≤ 2) were randomized 1:1 to recei...

In children with X-linked hypophosphatemia (XLH), excess circulating fibroblast growth factor 23 (FGF23) causes hypophosphatemia with consequent rickets, skeletal deformities, and impairments in growth and mobility. Compared to continuation with conventional therapy (oral phosphate and active vitamin D [Pi/D]), switching to treatment with burosumab, a fully human monoclonal antibody against FGF23, showed significantly greater improvement in phosphate homeostasis, rickets sever...

In children with XLH, high circulating levels of FGF23 cause hypophosphatemia with consequent rickets, skeletal deformities, and growth impairment. Conventional therapy consists of multiple daily doses of oral phosphate and active vitamin D (Pi/D). Burosumab is a fully human monoclonal antibody against FGF23 indicated for the treatment of XLH. In the active-control study CL301 (NCT02915705), 61 children with XLH (1–12 years old) were randomized (1:1) to receive subcutaneo...

In a randomized open-label phase 3 trial in 62 children (1–12 years) with X-linked hypophosphatemia (XLH) (NCT 02915705), switching from conventional therapy (oral phosphate plus active vitamin D) to burosumab, a monoclonal antibody targeting fibroblast growth factor 23, significantly improved serum phosphate concentration, rickets, lower-extremity deformities, growth, mobility, and patient-reported outcomes (PROs) at 64 weeks. Children in Europe, USA, Canada, and Australia wh...