1. Upon request of the competant authorithy exclusion criteria Nos. 2, 3, and 26 were described more precisely by using threshold levels. No 2. severe renal impairment (i.e. eGFR < 59 mL/min/1.73 m2 determined from serum creatinine during screening) No. 3. severe heart failure (i.e. NYHA III/IV) No.26. laboratory values out of normal range unless the deviation from normal is judged as not relevant for the clinical trial by the investigator or if the following thresholds have been reached (haemoglobin < 6.2 mmol/l, leukocytes <2500 / µl, platelets < 60000 / µl). For calculation of the eGFR the MDRD formula has been added to chapter 13.5.6.1 “Description of measurements” as follows: The eGFR at screening will be calculated from the creatinine concentration measured in serum according to the following formula : eGFR [mL/min/1.73 m2] = 175 × [Creatinine in Serum (mg/dL)]-1.154 × [Age (years)]-0.203 × (0.742 if female) × (1.212 if African American) 2. According to the Guideline on the evaluation of drugs for the treatment of gastro-oesophageal reflux disease the wash out phase of PPIs was adapted from 3 to 4 weeks prior to screening (exclusion criteria 18) and also 4 weeks prior to baseline visit via re-check of exclusion criteria (exclusion criteria No. 27). 3. According to the final protocol an independent representative of the sponsor will be involved in the DMC. Upon request of the authority preventive measures, which will be taken to avoid accidental transfer of non-blinded data have been added in the protocol.

1. Upon request by the leading Ethics Committee an exclusion criteria was added in the protocol, which prevents the participation in the clinical trial due to intake of potential stomach damaging medication. Thus, exclusion criteria No. 17 "continuous treatment with nonsteroidal anti-inflammatory drugs (NSAIDs e.g. piroxicam, ketoprofen, diclofenac, acetylsalicylic acid or indomethacin (occasionally treatment with NSAIDs or except for ASS 100 mg daily is permitted, see also chapter 13.4.4.))" was adapted. Furthermore, in chapter 13.4.4 a paragraph regarding permitted medication was added and the original wording adapted. 2. During planning of the trial, it was observed, that the exclusion criterion No. 2 “severe renal impairment (i.e. eGFR1 < 59 mL/min/1.73 m2 determined from serum creatinine during screening)” cannot be assessed on visit 1 as the result of creatinine is not yet available on visit 1. Thus, the exclusion criterion was adapted to "signs of severe renal impairment known from medical history or reported during screening examination". The originally exclusion criterion No. 2 will now be assessed on visit 2 before randomisation and treatment with the IMP will start. Thus, the exclusion criterion "severe renal impairment (i.e. eGFR ≤ 29 mL/min/1.73 m2 determined from serum creatinine during screening) was added as No. 26 determined at baseline visit.. However, the limit was adapted from eGFR of ≤ 59 mL/min/1.73 m2 to ≤ 29 mL/min/1.73 m2 as erroneously 59 mL/min/1.73 m2 represents the upper limit of the classification of moderate renal impairment and not the limit for severe." 3. Furtheremore, documentation in CRF and diary was adapted with regard to date of inclusion, date of randomsiation and information on daily fluid in the administrative period.

In accordance with the Scientific Advice, patients were included based on a gastric endoscopic examination within the last year prior indicating a Los Angeles classification of grade A or better in endoscopic examination. The participating Principal Investigators informed the sponsor, that this request is not in accordance with the common medical practice since the new version of the German medical guideline “S2k-Leitlinie 021/013 Gastroösophageale Refluxkrankheit” (version dated June 14th, 2014) came into effect. According to this a gastric endoscopic examination should not be performed as long as due to typical symptoms of a reflux disease like heartburn a GERD can be estimated as long as no alarm symptoms like dysphagia and odynophagia, non-intended weight loss of >5% or anaemia, especially in case of information about blood loss in the GI-tract or clinical information with regard to complications such as development of esophageal/epigastric mass, strictures and/or, ulceration exist. Furthermore, investigations of Malfertheiner et al. (ProGERD study) have showed, that in patients with primary symptom of heartburn and non-erosive (NERD), erosive reflux disease (ERD), or LA grades A-D (Los Angeles classification) during the 5 year follow-up period only a few patients with NERD and mild/moderate ERD progressed to severe forms of ERD or Barrett's oesophagus. Most GERD patients remain stable or improve over a 5-year observation period under current routine clinical care and also for patients with oesophagitis, they remained stable or showed improvement. Thus, inclusion criteria No. 04 was adapted and an endoscopic examination witin the last 5 years was accepted for inclusion.

Dr. Cornelius Koch will resign from his position as Coordinating Investigator of the trial and as Principal Investigator for the site Erfurt by March 31st 2020. Subsequently, Dr. Frank Donath will take over as Coordinating Investigator and Principal Investigator for the site Erfurt.

As during the trial the public life restrictions due to COVID-19 pandemic came into effect, the study protocol was adapted to allowed a remotely performance of for V2 to V5. Thus, all chapters describing measures to be performed on V2 to V5 have been adapted accordingly.

According to previous protocol version recruitment was intended to be stopped during the time of the interim analysis. In case the sample size does not suffice the study may be continued after the interim analysis. However, to compensate the significantly delayed recruitment as a result of the Covid-19 pandemic a formal stop of the recruitment was not realised to allow for uninterrupted recruitment procedures in case further subjects are needed. Furthermore, the protocol did not state how potentially occurring overrunning subjects shall be handled biometrically. Thus, with Amendment 06 the procedure is clarified in accordance with the EMA requirements for adaptive designs. Overrunning patients will not have an impact on the planned interim analysis. Overrunning patients - will become part of the populations of the 2nd stage, in case of continuation of the trial, or - these patients will be included in an additional analysis that will be provided based on all randomized patients and will be considered the final analysis, in case of discontinuation.