| E.1 Medical condition or disease under investigation | 
| E.1.1 | Medical condition(s) being investigated  | 
| severe asthma | 
 
| schweres Asthma | 
 
 
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| E.1.1.1 | Medical condition in easily understood language  | 
| severe asthma | 
 
| schweres Asthma | 
 
 
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| E.1.1.2 | Therapeutic area  | Diseases [C] - Respiratory Tract Diseases [C08] | 
| MedDRA Classification | 
| E.1.3 | Condition being studied is a rare disease  |  No  | 
| E.2 Objective of the trial | 
| E.2.1 | Main objective of the trial  | 
| - To investigate the effect of vitamin D as add-on therapy to inhaled or oral corticosteroids necessary to control asthma in vitamin D insufficient patients with severe disease | 
 
 
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| E.2.2 | Secondary objectives of the trial  | 
- To evaluate the effects on rate and time to first and subsequent exacerbations.
 - To evaluate the effects on a range of asthma-related clinical and functional Parameters (e.g. ACQ-5 score, AQLQ score, BDI / TDI, FVC, FEV1, RV, TLC, airway resistance, IC, DLCO, serum concentrations of vitamin D, parathormone, calcium, interleukins (IL) 10 and 17, and TNF-alpha | 
 
 
 | 
| E.2.3 | Trial contains a sub-study  |  No  | 
| E.3 | Principal inclusion criteria  | 
Subjects meeting all of the following criteria will be considered for enrolment into the trial:
 - Male or female, age ≥ 18 years with a pulmonary specialist diagnosis of severe asthma according to the Global Initiative for Asthma (GINA 2014, www.ginasthma.org) and the German Asthma Net (GAN, www. German-asthmanet.de)
 - Treatment with long-acting β2-agonists (LABA) and inhaled corticosteroids (ICS) at a dose of at least 1000 μg beclomethasone (or equivalent) per day, chronic oral corticosteroid (OCS) use is allowed
 - Asthma Control Questionnaire (ACQ-5) score ≥ 1.5
 - Vitamin D insufficiency as defined by a serum vitamin D concentration of <30 ng/ml but ≥ 10 ng/ml at screening | 
 
 
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| E.4 | Principal exclusion criteria | 
Subjects presenting one of the following criteria will not be enrolled in the trial:
 - Patients on vitamin D substitution
 - Impaired renal function (GFR < 30 ml/min) and history of physician-diagnosed nephrolithiasis
 - Within the past 4 weeks respiratory tract infection or asthma exacerbation requiring systemic corticosteroids or increase in systemic corticosteroids
 - Chronic respiratory diseases (other than asthma)
 - Current smokers or ex-smokers with a smoking history of more than 10 packyears | 
 
 
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| E.5 End points | 
| E.5.1 | Primary end point(s) | 
Relative dose reduction of ICS (μg beclomethasone or equivalent/day) or OCS (mg prednisone or equivalent/day) at the end of study phase II, defined as [initial dose at week 0 – dose at end of phase II (week 24)] / initial dose at week 0. If the dose at end of Phase II has been reduced compared to week 0 and this was followed by an exacerbation within 4 weeks after reduction, the dose before that reduction will be used for the calculation of
 relative dose reduction. | 
 
 
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| E.5.1.1 | Timepoint(s) of evaluation of this end point | 
 | 
| E.5.2 | Secondary end point(s) | 
- Exacerbations (rate of and time to first and subsequent exacerbations)
 - ACQ-5 score, AQLQ score, BDI / TDI
 - FVC, FEV1, RV, TLC, airway resistance, IC, DLCO
 - Serum concentrations of vitamin D, parathormone, calcium, interleukins (IL) 10 and 17, as well as TNF-alpha
 - Proportion of patients that achieved vitamin D sufficiency (vitamin D responder: 25-hydroxyvitamin D level ≥ 30 ng/mL)
 - Assessment of safety and tolerability by documentation of adverse events (AEs), serious adverse events (SAEs), vital signs, physical examination and laboratory parameters (laboratory test abnormalities/test value changes over time) | 
 
 
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| E.5.2.1 | Timepoint(s) of evaluation of this end point | 
week 4
 week 8
 week 12
 week 14
 week 18
 week 20
 week 24 | 
 
 
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| 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 |  No  | 
| 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) |  No  | 
| E.7.4 | Therapeutic use (Phase IV) |  Yes  | 
| E.8 Design of the trial | 
| E.8.1 | Controlled |  Yes  | 
| E.8.1.1 | Randomised |  Yes  | 
| E.8.1.2 | Open |  No  | 
| E.8.1.3 | Single blind |  No  | 
| E.8.1.4 | Double blind  |  Yes  | 
| E.8.1.5 | Parallel group |  Yes  | 
| 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  |  Yes  | 
| E.8.2.3 | Other |  No  | 
| E.8.2.4 | Number of treatment arms in the trial | 2 | 
| 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 | 13 | 
| 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 |  No  | 
| E.8.6.2 | Trial being conducted completely outside of the EEA |  No  | 
| 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
                     | 
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| E.8.9 Initial estimate of the duration of the trial | 
| E.8.9.1 | In the Member State concerned years | 2 | 
| E.8.9.1 | In the Member State concerned months | 0 | 
| E.8.9.1 | In the Member State concerned days | 0 |