Efficacy and Safety of Burosumab Versus Oral Phosphate and Active Vitamin D Treatment in Pediatric Patients With XLH

Inclusion Criteria

• Male or female, aged 1 to ≤12 years with radiographic evidence of rickets as determined by central readers
• Phosphate-regulating endopeptidase homolog, X-linked (PHEX) mutation or variant of uncertain significance in either the patient or in a directly related family member with appropriate X-linked inheritance
• Biochemical findings associated with XLH: serum phosphorus 50th based on country-specific norms
• Use of aluminum hydroxide antacids (eg, Maalox® and Mylanta®), systemic corticosteroids, acetazolamide, and thiazides within 7 days prior to the Screening Visit
• Current or prior use of leuprorelin (eg, Lupron®, Viadur®, Eligard®), triptorelin (TRELSTAR®), goserelin (Zoladex®), or other drugs known to delay puberty
• Use of growth hormone therapy within 12 months before the Screening Visit
• Presence of nephrocalcinosis on renal ultrasound grade 4
• Planned orthopedic surgery, including osteotomy or implantation or removal of staples, 8 plates, or any other hardware, within the first 40 weeks of the study
• Hypocalcemia or hypercalcemia, defined as serum calcium levels outside the age-adjusted normal limits
• Evidence of hyperparathyroidism (parathyroid hormone [PTH] levels 2.5X upper limit of normal [ULN])
• Use of medication to suppress PTH (eg, cinacalcet, calcimimetics) within 2 months prior to the Screening Visit
• Presence or history of any condition that, in the view of the investigator, places the subject at high risk of poor treatment compliance or of not completing the study.
• Presence of a concurrent disease or condition that would interfere with study participation or affect safety
• History of recurrent infection or predisposition to infection, or of known immunodeficiency
• Use of a therapeutic monoclonal antibody within 90 days prior to the Screening Visit or history of allergic or anaphylactic reactions to any monoclonal antibody
• Presence or history of any hypersensitivity to KRN23 excipients that, in the judgment of the investigator, places the subject at increased risk for adverse effects
• Use of any investigational product or investigational medical device within 30 days prior to screening, or requirement for any investigational agent prior to completion of all scheduled study assessments. OR, in Japan, use of any investigational product or investigational medical device within 4 months prior to screening, or requirement for any investigational agent prior to completion of all scheduled study assessments