Study to Assess the Safety, Pharmacokinetics and Efficacy of KRN23 in Adult Chinese Patients With TIO

Inclusion criteria

• . Have a clinical diagnosis of TIO based on evidence of excessive FGF23 that is not amenable to cure by surgical excision of the offending tumor (documented by Investigator)
• . Male or female Chinese patients aged ≥18 years at the time of signing the informed consent form
• . Have a fasting serum phosphorus level \< 2.5 mg/dL (0.81 mmol/L) at Screening
• . Have a serum iFGF23 level ≥ 100 pg/mL by Kainos assay at Screening
• . Have a TmP/GFR \< 2.5 mg/dL at Screening
• . Have an estimated glomerular filtration rate (eGFR) ≥ 60 mL/min/1.73m2(using CKD-EPI formula) at Screening. Subjects with an eGFR ≥ 30 but \< 60 mL/min at screening will be considered eligible so long as in the opinion of the Investigator the decline in renal function is not related to nephrocalcinosis
• . Have a corrected serum calcium level \< 10.8 mg/dL (2.69 mmol/L) at Screening (Corrected serum calcium = serum calcium in mg/dL + 0.8 × \[4 - serum albumin in g/dL\])
• . Have a negative pregnancy test at Screening and be willing to have additional pregnancy tests during the study (female patients of child-bearing potential only)

Exclusion criteria