| E.1 Medical condition or disease under investigation | 
| E.1.1 | Medical condition(s) being investigated |  | 
| E.1.1.1 | Medical condition in easily understood language |  | 
| E.1.1.2 | Therapeutic area | Diseases [C] - Musculoskeletal Diseases [C05] | 
| MedDRA Classification | 
| E.1.2 Medical condition or disease under investigation | 
| 
| E.1.2 | Version | 19.0 |  
| E.1.2 | Level | PT |  
| E.1.2 | Classification code | 10031243 |  
| E.1.2 | Term | Osteogenesis imperfecta |  
| E.1.2 | System Organ Class | 10010331 - Congenital, familial and genetic disorders |  | 
| E.1.3 | Condition being studied is a rare disease | Yes | 
| E.2 Objective of the trial | 
| E.2.1 | Main objective of the trial | 
| To evaluate the effect of denosumab on lumbar spine bone mineral density (BMD) Z-score at 12 months, as assessed by dual-energy X-ray absorptiometry (DXA), in children 2 to 17 years of age with osteogenesis imperfecta (OI). |  | 
| E.2.2 | Secondary objectives of the trial | 
| To evaluate denosumab in children 2 to 17 years of age with OI with respect to: - Change in lumbar spine BMD Z-score, as assessed by DXA, at 6, 18, 24, and 36 months
 - Change in proximal femur BMD Z-score, as assessed by DXA, at 6, 12, 18, 24, and 36 months (in subjects 5 years of age and older)
 - Incidence of x-ray confirmed long bone and new and worsening vertebral fractures from pre-treatment to post-treatment at 12, 24, and 36 months
 - Incidence of improving vertebral fractures from pre-treatment to post-treatment at 12, 24, and 36 months (overall, among subjects with clinical fracture reduction, and among subjects with clinical fracture increase)
 - Incidence of pre-treatment compared with post-treatment vertebral and nonvertebral fractures at 12, 24, and 36 months
 + Exploratory and Safety objectives
 For complete list, please refer to the protocol
 |  | 
| E.2.3 | Trial contains a sub-study | Yes | 
| E.2.3.1 | Full title, date and version of each sub-study and their related objectives | 
| PK/bone turnover markers (BTM) substudy of approximately 50 subjects to - determine serum concentration of denosumab at 1 and 10 days and 6, 12, 18, 24, 30, and 36 months in all subjects
 - evaluate changes observed in bone turnover markers (bone-specific alkaline phosphatase [BSAP], serum type I collagen C-telopeptide [sCTX])
 |  | 
| E.3 | Principal inclusion criteria | 
| - Informed consent (to be provided by parent or legal guardian) and informed assent (to be provided by subjects when age-appropriate). - Children aged 2 to 17 years inclusive at screening
 - Clinical diagnosis of OI defined as a clinical history consistent with type I-IV OI as determined by presence of expected phenotype (examples include: facial shape, voice, blue sclera, dentinogenesis imperfecta, typical radiographic features, fracture pattern) and lack of additional features unrelated to type I-IV OI (eg, blindness, mental retardation, neuropathy, craniosynostosis; premature exfoliation of deciduous teeth)
 * If familial, also must be autosomal dominant
 -  Clinical severity of OI as defined by
 o 2 or more prevalent vertebral compression fractures; OR
 o 1 prevalent vertebral compression fracture and 1 or more nonvertebral fractures within the previous 2 years; OR
 o 3 or more fractures within the previous 2 years
 |  | 
| E.4 | Principal exclusion criteria | 
| Subjects meeting any of the following criteria at screening are not eligible for enrollment: - Inability or unwillingness to comply with the requirements for frequent calcium and phosphorus monitoring for 14 days after the first dose of denosumab (only applies to the first 5 subjects age 11 to17 enrolled in the study and the first 5 subjects of any age meeting the criteria for increased bone turnover (see Section 2.3.2.1)
 - Currently unhealed fracture or osteotomy as defined by orthopedic opinion
 - Osteotomy within 5 months of screening
 - Evidence of untreated oral cavities or oral infections
 - Recent or planned invasive dental procedure
 - Surgical tooth extraction which has not healed by screening
 - History of an electrophoresis pattern inconsistent with type I to IV OI
 - History of known mutation in a gene other than COL1A1/COL1A2 causing OI or metabolic bone disease
 - Abnormalities of the following per central laboratory reference ranges at screening:
 o Serum albumin corrected calcium < lower limit of normal (LLN)
 o Serum vitamin D < 20 ng/mL; re-screening for Vitamin D level < 20 ng/mL will be allowed, after adequate supplementation
 o Aspartate aminotransferase (AST), alanine aminotransferase (ALT) > 1.5 x upper limit of normal (ULN)
 o Total bilirubin (TBL) > 1.5 x ULN (subjects with Gilbert syndrome are eligible)
 o Serum phosphorus < LLN
 o Serum alkaline phosphatase > 20% above the ULN or > 20% below the LLN
 - Estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2 (calculated by the Schwartz equation at screening)
 - Evidence of any of the following:
 o Current hyperthyroidism (unless well-controlled on stable antithyroid therapy)
 o Current clinical hypothyroidism (unless well-controlled on stable thyroid replacement therapy)
 o History of hyperparathyroidism
 o Current hypoparathyroidism
 o Current, uncontrolled hypercalcemia (albumin-corrected serum Ca >10% ULN)
 o History of osteomalacia or rickets (chart review)
 o Other bone diseases that affect bone metabolism (eg, osteoporosis pseudoglioma syndrome, idiopathic juvenile osteoporosis, osteopetrosis, hypophosphatasia)
 o History of autoimmune disease
 o History of malabsorption (in children with serum albumin < LLN, malabsorption should be clinically ruled out by the PI to confirm eligibility)
 o History of rare hereditary problems of fructose intolerance
 o History of long QT syndrome
 o History of non-healing osteotomy
 o History of malignancy
 o History of alcohol or drug abuse
 o History of any solid organ or bone marrow transplant
 o Contraindicated or poorly tolerant of denosumab therapy
 - Positive blood screen for human immunodeficiency virus -1 or -2
 antibody
 - Positive blood screen for hepatitis B surface antigen or hepatitis C antibody
 - Currently pregnant or planning a pregnancy during the study and for an additional 5 months after the last dose of denosumab
 - For sexually active girls: refusal to use highly effective methods of contraception and to continue this practice for 5 months after the last injection of denosumab
 |  | 
| E.5 End points | 
| E.5.1 | Primary end point(s) | 
| Change from baseline in lumbar spine BMD Z-score, as assessed by DXA, at 12 months. |  | 
| E.5.1.1 | Timepoint(s) of evaluation of this end point |  | 
| E.5.2 | Secondary end point(s) | 
| - Change from baseline in lumbar spine BMD Z-score, as assessed by DXA, at 6, 18, 24, and 36 months - Change from baseline in proximal femur BMD Z-score, as assessed by DXA, at 6, 12, 18, 24, and 36 months (in subjects 5 years of age and older)
 - Subject incidence of x-ray confirmed long bone and new and worsening vertebral fractures at 12, 24, and 36 months compared to pre-treatment
 - Subject incidence of improved vertebral fractures at 12, 24, and 36 months compared to pre-treatment (overall, among subjects with clinical fracture reduction and among subjects with clinical fracture increase)
 - Subject incidence of vertebral and nonvertebral fractures at 12, 24, and 36 months  compared to pre-treatment
 - Change from baseline in CHQ-PF-50 Physical Summary score at 12, 24, and 36 months
 - Change from baseline in CHQ-PF-50 Psychological Summary score at 12, 24, and 36 months
 - Change from baseline in CHAQ Disability Index score at 12, 24, and 36 months
 - Change from baseline in WBFPRS at 12, 24, and 36 months
 - Change from baseline in growth velocity (determined by calculating age-adjusted Z-scores for height, weight and BMI) at 36 months
 - Serum concentration of denosumab at 1 and 10 days, and 6, 12, 18, 24, 30, and 36 months
 -  Serum concentration of denosumab at 1, 10, and 30 days, and 3, 6, 12, 18, 24, 30, and 36 months (PK/BTM substudy only)
 |  | 
| E.5.2.1 | Timepoint(s) of evaluation of this end point |  | 
| E.6 and E.7 Scope of the trial | 
| E.6 | Scope of the trial | 
| E.6.1 | Diagnosis | No | 
| E.6.2 | Prophylaxis | No | 
| E.6.3 | Therapy | Yes | 
| E.6.4 | Safety | Yes | 
| E.6.5 | Efficacy | Yes | 
| E.6.6 | Pharmacokinetic | Yes | 
| E.6.7 | Pharmacodynamic | No | 
| E.6.8 | Bioequivalence | No | 
| E.6.9 | Dose response | No | 
| E.6.10 | Pharmacogenetic | No | 
| E.6.11 | Pharmacogenomic | No | 
| E.6.12 | Pharmacoeconomic | No | 
| E.6.13 | Others | No | 
| E.7 | Trial type and phase | 
| E.7.1 | Human pharmacology (Phase I) | No | 
| E.7.1.1 | First administration to humans | No | 
| E.7.1.2 | Bioequivalence study | No | 
| E.7.1.3 | Other | No | 
| E.7.1.3.1 | Other trial type description |  | 
| E.7.2 | Therapeutic exploratory (Phase II) | No | 
| E.7.3 | Therapeutic confirmatory (Phase III) | Yes | 
| E.7.4 | Therapeutic use (Phase IV) | No | 
| E.8 Design of the trial | 
| E.8.1 | Controlled | No | 
| E.8.1.1 | Randomised | No | 
| E.8.1.2 | Open | Yes | 
| E.8.1.3 | Single blind | No | 
| E.8.1.4 | Double blind | No | 
| E.8.1.5 | Parallel group | No | 
| E.8.1.6 | Cross over | No | 
| E.8.1.7 | Other | No | 
| E.8.2 | Comparator of controlled trial | 
| E.8.2.1 | Other medicinal product(s) | No | 
| E.8.2.2 | Placebo | No | 
| E.8.2.3 | Other | No | 
| E.8.3 | The trial involves single site in the Member State concerned | No | 
| E.8.4 | The trial involves multiple sites in the Member State concerned | Yes | 
| E.8.4.1 | Number of sites anticipated in Member State concerned | 1 | 
| E.8.5 | The trial involves multiple Member States | No | 
| E.8.6 Trial involving sites outside the EEA | 
| E.8.6.1 | Trial being conducted both within and outside the EEA | Yes | 
| E.8.6.2 | Trial being conducted completely outside of the EEA | No | 
| E.8.6.3 | If E.8.6.1 or E.8.6.2 are Yes, specify the regions in which trial sites are planned | 
| Australia |  
| Bulgaria |  
| Canada |  
| Czech Republic |  
| France |  
| Germany |  
| Hungary |  
| Poland |  
| Spain |  
| United Kingdom |  
| United States |  | 
| E.8.7 | Trial has a data monitoring committee | Yes | 
| E.8.8 | Definition of the end of the trial and justification where it is not the last
                        visit of the last subject undergoing the trial | 
| the end of the trial is defined as the date when the last subject is last assessed for evaluation in the study, which corresponds to the month 36 visit. 
 |  | 
| E.8.9 Initial estimate of the duration of the trial | 
| E.8.9.1 | In the Member State concerned years | 6 | 
| E.8.9.1 | In the Member State concerned months |  | 
| E.8.9.1 | In the Member State concerned days |  | 
| E.8.9.2 | In all countries concerned by the trial years | 6 |