Metformin vs Tolvaptan for Treatment of Autosomal Dominant Polycystic Kidney Disease. A Phase 3a, Indipendent, Multicentre, Two Parallel Arms, Randomized Controlled Trial
Phase: PHASE3
Conditions: ADPKD
Sponsor: Azienda Ospedaliero-Universitaria Consorziale Policlinico di Bari

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CLINICAL NO PROFIT PROTOCOL 
 
 
 
EUDRACT NUMBER: 
2018-000477-77 
 
TITLE: 
Metformin versus Tolvaptan in adults with Autosomal Dominant 
Polycystic Kidney Disease (ADPKD): a phase 3a, independent, multi-
centre, 2 parallel arms randomized controlled trial 
 
STUDY NAME:  
METROPOLIS 
 
 
 
 
VERSION: 2 
 
VERSION DATE: 31 July 2018 
 
 
 
 
 
 
 
 
 
 
 

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SPONSOR 
Name:  Università degli Studi di Bari 
Dipartimento dell’Emergenza e dei Trapianti 
di organi (D.E.T.O.)   
Address: Piazza G.Cesare n.11-Policlinico- 
70124 Bari 
 
Phone: +39  0805478627- Ufficio protocollo 
+ 39080 5478614 
 
E mail : delfinamaria.misuraca@uniba.it 
Signature (  per lo sponsor ) 
Prof. Loreto Gesualdo  
 
CHAIRMAN/STUDY 
COORDINATOR 
Name:  Prof. Loreto Gesualdo -Direttore U.O. 
Nefrologia Universitaria – Azienda 
Policlinico di Bari 
 
 
Address: Piazza G.Cesare n.11 70124 Bari  
Phone:  + 39 080 5594041 
 
Fax: + 39 080 5478675 
 
Email:  trialnefrobari@gmail.com 
 
Prof. Loreto Gesualdo  
 
PRINCIPAL/COORDINATING 
INVESTIGATOR 
Name:  Prof. Loreto Gesualdo - Direttore U.O. 
Nefrologia Universitaria – Azienda 
Policlinico di Bari  
Address: Piazza G. Cesare n.11 70124 Bari  
Phone: + 39 080 5594041 
 
Fax:  39 080 5478675 
 
Email:  trialnefrobari@gmail.com 
 
Prof. Loreto Gesualdo  
 
 
MEDICAL WRITING 
Name:  Prof. Loreto Gesualdo;   
 
 
Name: Dr. Giovanni Piscopo 
 
 
 
 

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TABLE OF CONTENTS 
 
A. LIST OF ABBREVIATIONS ..................................................................................... 4 
1. SYNOPSIS ..................................................................................................................... 6 
2. INTRODUCTION AND RATIONALE .................................................................... 10 
3. OBJECTIVES ............................................................................................................. 29 
4. TRIAL DESIGN .......................................................................................................... 30 
5. POPULATION OF THE STUDY ............................................................................. 39 
6. TREATMENT ............................................................................................................. 43 
7. STUDY DURATION .................................................................................................. 48 
8. STUDY ENDPOINTS ................................................................................................. 49 
9. VISITS ......................................................................................................................... 51 
10. SAFETY MONITORING AND REPORTING ..................................................... 61 
11. TREATMENT/STUDY DISCONTINUATION .................................................... 77 
12. STATISTICAL CONSIDERATIONS .................................................................... 83 
13. ETHICAL CONSIDERATIONS ............................................................................. 85 
14. STUDY MONITORING .......................................................................................... 89 
15. FIGURES AND TABLES ........................................................................................ 93 
16. REFERENCE ............................................................................................................ 97 

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A. LIST OF ABBREVIATIONS 
ADPKD 
Autosomal dominant polycystic kidney disease 
ABG 
Arterial-blood gas 
AEs 
Adverse Events 
ALI 
Acute liver injury 
ALT 
Alanine aminotransferase 
AMPK 
Adenosine Monophosphate activated Protein Kinase 
AST 
Aspartate aminotransferase 
ATP 
Adenosine triphosphate 
AUC 
Area under the concentration time curve 
AVP 
Serum vasopression levels 
cAMP 
Cyclic adenosine monophosphate 
cAMP 
Cyclic adenosine monophosphate 
CBC 
Complete blood count 
CFTR 
Cystic fibrosis transmembrane conductance regulator 
CKD 
Chronic kidney disease 
CKD1 
Cyclin-dependent kinase1  
CKD-EPI 
Chronic kidney disease-Epidemiology 
Cmax 
Maximum concentration 
CRISP 
Consortium for Radiologic Imaging Study of Polycystic Kidney Disease 
CT 
Computed tomography 
CTEP 
Cancer Therapy Evaluation Program 
CYP 
Cytochrome 
EGF 
Epidermal growth factor 
eGFR 
Estimated Glomerular Filtration Rate 
EMA 
European Medicines Agency 
EoTx 
End of Treatment 
ESRD 
End-stage renal disease 
EU 
European Union 
GCP 
Good Clinical Practice 
HBV 
Hepatitis B infection 
HCV 
Hepatitis C virus 
HIV 
Human immunodeficiency virus 
HR 
Hazard Ratio  
ICF 
Informed consent forms 
ICH 
Conference on Harmonization 
ID 
Identification number 

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IEC 
Indipendent ethics committee 
IMP 
Investigational medicinal product 
IRE 
Irreversible electroporation 
IVRS 
Interactive voice response system 
MALA 
Metformin associated lactic acidosis 
MCP1 
Monocyte chemoattractant protein 1 
MPR 
Multi-planar Reconstructions 
MRI 
Magnetic Resonance Imaging 
mTOR 
Mammalian target of rapamycin 
mTORi 
Mammalian target of Rapamycin inhibitors 
NCI CTCAE Cancer Institute Common Terminology Criteria for Adverse Events 
NICE 
National Institute for Health and Clinical Excellence 
NSAID 
Nonsteroidal anti-inflammatory drugs 
OCT 
Organic Cations Transporter 
PC 
Polycystins 
PCOS 
Polycistic Ovary Syndrome 
PK 
Pharmacokinetics 
PKD1 
Polycystin 1 
PKD2 
Polycystin 2 
pVBGA 
Peripheral venous blood gas analysis 
QALY 
Quality-adjusted life years 
RAAS 
The renin–angiotensin system 
RCTs 
Randomized controlled trials 
RNA 
Ribonucleic acid 
SAE 
Serious adverse event 
SIADH 
The syndrome of inappropriate antidiuretic hormone secretion 
SmPC 
Summary of product characteristics 
SSN 
Sistema Sanitario Nazionale 
TKV 
Total kidney volume 
uEGF 
Urinary epidermal growth factor 
uMCP-1 
Urinary monocite chemotactic peptide-1 
UNL 
Upper Normal Limit 
USA 
United States of America 
VR 
Volume rendering 
WOCBP 
Women of childbearing potential 
EDC 
Electronic Data Capture 

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1. SYNOPSIS 
TITLE 
Metformin versus Tolvaptan in adults with Autosomal Dominant 
Polycystic Kidney Disease (ADPKD): a phase 3a, independent, 
multi-centre, 2 parallel arms randomized controlled trial 
SPONSOR 
Università degli Studi di Bari Dipartimento dell’Emergenza 
e dei Trapianti di organi (D.E.T.O.)   
PHASE 
III 
RATIONALE 
Autosomal dominant polycystic kidney disease (ADPKD) is the 
most common inherited renal disorder occurring in 1:400–1:1.000 
live births. It affects 4 to 6 million persons worldwide and about 
205.000 people in Europe (EU). This figure is equivalent to 4 in 
10.000 people and thus below the prevalence threshold of 5 in 
10.000 used to designate a disease as rare in EU. 
Renal cyst development and expansion in ADPKD involves both 
fluid secretion and abnormal proliferation of cyst-lining epithelial 
cells. The chloride channel of the cystic fibrosis transmembrane 
conductance regulator (CFTR) participates in secretion of cyst 
fluid, and the mammalian target of rapamycin (mTOR) pathway 
may drive proliferation of cyst epithelial cells. CFTR and mTOR 
are both negatively regulated by AMP-activated protein kinase 
(AMPK). Metformin, a drug widely used, is a pharmacological 
activator of AMPK. We found that metformin stimulates AMPK, 
resulting in inhibition of both CFTR and the mTOR pathways. 
Metformin induces significant arrest of cystic growth in both in 
vitro and ex vivo models of renal cystogenesis. In addition, 
metformin administration produces a significant decrease in the 
cystic index in two mouse models of ADPKD. These results 
suggest a possible role for AMPK activation in slowing renal 
cystogenesis as well as the potential for therapeutic application of 
metformin in the context of ADPKD 
OBJECTIVES 
Objective of the study is to assess if a two-year course of 1500 mg 
oral metformin is effective and safe in treatment of ADPKD, as 
compared to the actual gold-standard therapy, tolvaptan (Jinarc®) 
ENDPOINTS 
Primary outcome of the study is to evaluate the difference 
between Metformin and Tolvaptan in annualized slope of eGFR 
(CKD-EPI) for individual subjects, that will be calculated using 
an appropriate baseline and post-randomization assessment. 
The key secondary endpoint is the percent change from baseline 
in htTKV as measured by CT-scan at 24 months. 
The safety endpoin include:  
- 
changes from baseline in creatinine;  
- 
vital signs;  
- 
laboratory values including liver function tests, rate  

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of aquaretic AEs, thus including serum sodium, rate of Metformin 
Associated Lactic Acidosis, blood insulin and glucose levels, 
HOMA test in both treatment groups 
STUDY DESIGN 
This is a phase 3a, independent, multi-centre, parallel arms, 
randomized controlled trial comparing efficacy and safety of 
metformin and tolvaptan in ADPKD 
STUDY 
POPULATION 
This trial will enroll approximately 150 tolvaptan and metformin 
naïve subjects affected by Type I-truncating ADPKD, as they 
have grater probability of progression 
STUDY 
TREATMENT 
The trial contemplates a 2 weeks screening period (included in a 9 
months total recruitment period) during which 3 visits have to be 
collected (the 1st and the 2nd in three days, and the 3rd after 
biochemical analyses performed during the first two visits have 
been reviewed). The subject’s eligibility for the trial will be 
confirmed by the mean of eGFR calculated from the 2 pre-
treatment, central-lab, serum creatinine assessments. Longer 
screening periods (up to 4 additional weeks) are acceptable for 
subjects needing stabilization after changing or discontinuing 
other treatments, especially anti-hypertensives and diuretics.  
Once eligibility is assessed, patients will undergo non-contrast 
enhanced CT-scan of kidneys (if not performed within six months 
prior to randomization). 
Randomization visit will occur on Day -29. During this visit 
patients will be randomized (in a ratio 1:1 tolvaptan:metformin) to 
each arm of treatment and will start an IMP titration period (3 
weeks from -28 to -8). Subjects not tolerating the minimum IMP 
dose will be considered “Titration failures” and will complete End 
of Treatment (EoTx) visit assessments and will be followed up 
after 7 days by phone call to assess any ongoing AEs. Subjects 
tolerating the minimum IMP dose enter the unblind run-in period 
(1 week from Day -7 to -1). During the “Run-in” phase, subjects 
will continue on a stable IMP dose to confirm tolerability over a 
longer period. At the end of the run-in period (Day -1), subjects 
not tolerating the minimum IMP dose will be considered “Run-in 
failures” and will complete EoTx visit assessments and will be 
followed up after 7 days by phone call to assess any ongoing AEs. 
Subjects completing the run-in will start the open-label 24 months 
treatment period, during which visits will be collected three-
monthly. At the end of the 24th month, and in case of early 
treatment cessation, follow-up period (3 weeks from +8 to +21) 
will start, during which 2 visits have to be collected. No IMP will 
be administered during this period 
NUMBER OF 
SUBJECTS AND 
SITES 
This trial will enroll approximately 150 tolvaptan and metformin 
naïve subjects and will be conducted in about 11 Italian Hospital 
Nephrology Departments 

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INCLUSION 
CRITERIA 
1) Men and women aged between 18 and 50 years 
2) eGFR (CKD-EPI) ≥ 45 ml/min/1,73 m2 
3) Genetic Diagnosis of Type I ADPKD truncating mutation 
4) Signed and dated informed consent 
EXCLUSION 
CRITERIA 
1) Women of childbearing potential (WOCBP) who do not agree 
to practice 2 different methods of birth control or remain abstinent 
during the trial and for 30 days after the last dose of IMP. If 
employing birth control, 2 of the following precautions must be 
used: vasectomy of partner, tubal ligation, vaginal diaphragm, 
intrauterine device, birth control implant, condom, or sponge with 
spermicide. Non-childbearing potential in women is defined as 
female subjects who are surgically sterile (ie, have undergone 
bilateral oophorectomy or hysterectomy) or female subjects who 
have been postmenopausal for at least 12 consecutive months.  
2) Women who are breast-feeding and/or who have a positive 
pregnancy test result prior to receiving investigational medical 
product (IMP).  
3) 
Treatment 
with 
acarbose, 
guar 
gum, 
cimetidin, 
phenprocoumon, 
oral 
anticoagulants, 
thrombolytic 
drugs, 
diuretics, ranolazin, cephalexin.  
4) Evidence of active systemic or localized major infection at the 
time of screening.  
5) Hepatic impairment or liver function abnormalities other than 
that expected for ADPKD with typical cystic liver disease during 
the screening period as defined by: 
o 
AST O ALT >8x UNL  
o 
AST O ALT >5x UNL >2 WEEKS 
o 
AST O ALT >3x UNL E BT >2x UNL OR INR >1,5  
o 
AST O ALT >3x UNL E SIGNS AND SYMPTOMS OF 
LIVER DAMAGE (fatigue, anorexy, nausea, vomiting, right 
hypocondrium pain, fever, jaundice, skin rash, itching) 
6) Acute or chronic disease causing tissue hypoxia (e.g.: 
myocardial failure, severe arythmias, myocardial infarction, 
respiratory failure, liver failure, alcohol acute intoxication, 
alcoholism, dehydration). 
7) Previously diagnosed diabetes already in treatment with other 
hypoglycemic drugs. 
8) Ongoing breast feeding.  
9) Use of any other investigational drug or treatment up to 4 
weeks before enrollment and during the treatment phase. 
10) Known hypersensitivity to metformin and its derivatives. 
11) Psychiatric disorders and any condition that might prevent full 
comprehension of the purposes and risks of the study.  
12) Malignancies within three years before enrolment in the 

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study.  
13) HIV, HBV, HCV infection. 
14) Urinary tract obstruction. 
INVESTIGATIONAL 
PRODUCT(S) 
Metformin (Zuglimet®) and Tolvaptan (Jinarc®) 
STATISTICAL 
ANALYSIS 
We plan to recruit a total of 150 patients which are currently 
within reach of the network coordinated by the proponent and 
composed by 11 Nephrology Centres. This network treats a total 
of 1500 (already genetically studied) patients of which we expect 
(based on standard response rates recognized in the population) 
acceptance to participate in the study to a value of approximately 
40% of patients. These will be then allocated to the experimental 
and control intervention. 
The selected sample is adequate to evaluate a significant 
reduction in the slope of eGFR at 2 years by 10%, which is a 
clinically relevant piece of information at the current state of 
knowledge, as well as a complete assessment of the benefits-
harms trade-off of the two interventions. 
STUDY DURATION 
Study Duration:  
The trial has a 36 months overall duration, that include a 9 months 
recruitment period 
Screening Period:  
Has a 2 weeks duration, it is included in the 9 months recruitment 
period 
Treatment Period: 
It has a 25 months duration. Each month lasts 28 days. It includes 
the 3 weeks titration period and the 1 week run-in period. 
Post-Treatment Follow-up Period: 
It lasts 21 days 
Total Study Duration:  
About 3 years 
 

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2. INTRODUCTION AND RATIONALE 
2.1 Disease Background 
Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited 
renal disorder occurring in 1:400–1:1.000 live births. It affects 4 to 6 million persons 
worldwide and about 205.000 people in Europe (EU). This figure is equivalent to 4 in 
10.000 people and thus below the prevalence threshold of 5 in 10.000  used to designate 
a disease as rare in EU (1). 
ADPKD is a heterogeneous disorder existing in two types: type I is caused by mutations in 
the PKD1 gene (encoding for Polycystin 1) and accounts for 85 to 90 percent of cases (2); 
type II is caused by mutations in the PKD2 gene (encoding for Polycystin 2)  accounting 
for 10 to 15 percent (3). 
Tremendous cystic enlargement of both kidneys is characteristic of ADPKD and even if 
relatively 
oligosymptomatic 
during 
the 
first 
three 
decades 
of 
life, 
renal 
insufficiencyimpaired renal function usually occurs suddenly after the 4th decade. Even 
with normal renal function, patients present with hypertension, hematuria, polyuria, flank 
pain, renal stones, and are prone to recurrent urinary tract infections. 
In addition to renal cysts, clinically relevant cysts are also common in liver (particularly in 
women), pancreas, intestine, seminal vesicles, arachnoid membrane and spinal meninges. 
Patients with ADPKD have an increased risk of aortic aneurysms and heart-valve defects. 
Cardiovascular complications are the most common cause of morbidity and mortality (4). 
Other complications comprise abdominal wall hernias and colon diverticula, and some 
kindred have five-fold increased risk of sudden death from ruptured intracerebral 
aneurysms compared to the general population (5). 

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The mechanism of cysts formation in ADPKD has been comprehensively analyzed in 
recent years, and several preclinical studies and clinical trials have been carried out in 
order to assess specific drugs’ efficacy and safety in treatment of ADPKD. 
The polycystins (PC) constitute a subfamily of protein channels and are thought to regulate 
intracellular calcium signaling. They are expressed in many tissues, including renal tubular 
epithelia, hepatic bile ducts, and pancreatic ducts. PC-1 is localized in the primary cilium 
and structures and is involved in cell-cell contacts (e.g., tight junctions). PC-1 probably 
functions as a receptor and/or adhesion molecule, whereas PC-2, a calcium-permeable 
nonselective cation channel, is found on the primary cilium, endoplasmic reticulum, and 
the plasma membrane. These PCs interact to form the PC complex, which is localized in 
the primary cilia and plays a role in intracellular calcium regulation. 
Cystogenesis in ADPKD is not fully understood, but mutations in PKD1 or PKD2 lead to a 
reduction in intracellular calcium, an increase in cyclic adenosine monophosphate (cAMP), 
activation of protein kinase A, and an increase in sensitivity of collecting duct principal cells 
to the constant tonic effect of vasopressin. The disruption in calcium signaling, coupled 
with enhanced cAMP signaling, activates downstream signaling pathways responsible for 
impaired tubulogenesis, cell proliferation, increased fluid secretion, and interstitial 
inflammation. 
Abnormal epithelial chloride secretion occurs through the cAMP-dependent transporter 
encoded by the CFTR gene and plays an important role in generating and maintaining 
fluid-filled cysts in ADPKD. Other pathogenic pathways may include activation of mTOR, 
Wnt, or hedgehog signaling; direct effects of PC-1 fragments on gene transcription; and 
increased aerobic glycolysis (6). Interestingly, both these pathogenic pathways may be 
influenced by metformin (7). 

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To date, only Tolvaptan (Jinarc®) has been proved as effective in reducing cystogenesis in 
specific subsets of ADPKD patients and therefore approved (in 2013 by EMA and in 2017 
by AIFA) for the treatment of this disease. However, it requires additional monthly 
monitoring, because of potential liver toxicity. Moreover it causes discomfort due to 
significant polyuria. AIFA, also according to the Società Italiana di Nefrologia (SIN) position 
statement (8), stated that, despite Jinarc® is indicated for all patients affected by ADPKD 
and chronic kidney disease (CKD) stages I-II-III, only those with evidence of fast 
progressing disease can benefit from Sistema Sanitario Nazionale (SSN) reimbursement 
of the treatment costs. 
AIFA Reimbursement criteria indicate those patients that may benefit the most from the 
therapy.. These criteria are the following: 
- 
CKD stage II and IIIa (based on GFR estimated using CKD-EPI or measured) 
- 
Nephromegaly as defined by: 
o Kidney length > 16,7 cm or 
o Total Kidney Volume (TKV) > 750 ml or 
o Heigh normalized TKV (htTKV) > 600 ml/m 
- 
Rapidly progressing disease as defined by: 
o GFR loss > 5 ml/min/1,73m2/year within 12 months or 
o GFR loss > 2,5 ml/min/1,73m2/year within 5 years or 
o TKV increase ≥ 5%/year as recorded by repeated CT or RMN measurement 
(at least 3) or  
o htTKV Class 1C-1D-1E according to Mayo Classificator (9) or 
o PROPKD score > 6 (10) 
A 12 months retrospective study conducted (11) on 243 patients in Northern Europe 
enrolled between April and December 2014 showed that employment rates were lowest 

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among dialysis patients; only 18% of those aged < 65 years were employed. The overall 
work productivity loss ranged between 9% in CKD stage 1–3 to 42% in dialysis patients. 
The average total annual costs amounted to €9,919 in CKD stage 1–3, €16,761 in CKD 
stage 4–5, €74,015 in dialysis patients and € 31,496 in transplant recipients (p<0.0001). 
Productivity loss was a major driver of costs across all stages of disease, reaching 72% of 
total costs in CKD stage 1–3 and ranging from €8,339 in CKD stage 1–3 to €19,598 in 
dialysis patients.  
Direct medical costs were substantial among dialysis patients, with maintenance dialysis 
alone accounting for 58% of total costs. Costs associated with ADPKD increase 
substantially as the patient progresses to dialysis. Interventions that can slow the 
progression of the disease have the potential to lead to substantial reductions in costs and 
patient burden. 
On the other hand, as reported by Erickson et al. costs analysis (12) of the TEMPO trial 
(13), initiating therapy with tolvaptan in 40 year-olds with ADPKD and eGFR of 80 
ml/min/1.73m2 delayed the median age of developing ESRD by 6.3 years in women and 
6.8 years in men. Tolvaptan therapy yielded an average increase in life expectancy of 2.8 
years in women and 2.3 years in men. Therapy with tolvaptan yielded an increase of 1.2 
discounted quality-adjusted life years (QALY) in women and 1.1 discounted QALYs in 
men. Total lifetime medical costs were substantially higher in patients receiving tolvaptan 
($858,300 higher in women and $830,100 higher in men). Combining health benefits and 
costs, for this patient group, tolvaptan therapy cost $720,600 per QALY gained in women 
and $769,500 in men. In a balanced cohort of women and men, tolvaptan increased 
median time to ESRD by 6.5 years, increased life expectancy by 2.6 years, and cost 
$744,100 per QALY gained. 

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Tolvaptan therapy was less cost-effective when given to patients with slower rates of 
eGFR decline. When tolvaptan is given to patients with a rate of eGFR decline of 2.4 
ml/min/1.73m2/year (the rate observed in a large cohort of ADPKD patients) tolvaptan cost 
$1,215,200 per QALY gained. Because, for a given eGFR when starting tolvaptan, older 
patients are more likely to die from other causes before experiencing CKD progression, 
tolvaptan was less cost-effective in older patients. For instance, tolvaptan cost 54% more 
per QALY gained in 65 year-olds ($1,147,800 per QALY gained) compared to 40 year-
olds. The cost per QALY gained also depended on the eGFR at which tolvaptan was 
begun. The cost per QALY gained in 40 year-olds was 16% lower when tolvaptan is 
started at an eGFR of 75 ml/min/1.73m2 ($626,938 per QALY) compared to the base case 
with a starting eGFR of 80 ml/min/1.73m2. 
Tolvaptan therapy would be more cost-effective if it were offered at a lower price. At a 
willingness to pay threshold of $100,000 per QALY gained, therapy with tolvaptan would 
be cost-effective in both men and women if offered at or below $1,155 per month (80% 
below the base case price and 94% below the current price per milligram). At a willingness 
to pay threshold of $50,000 per QALY gained, therapy with tolvaptan would be cost-
effective in both men and women if offered at or below $805 per month (86% below the 
base case price and 96% below the current price per milligram). 
A daily 1500 mg dose of metformin may cost about €6 per month (not taking into account 
potential costs deriving from potential side effects), thus yielding a substantial money 
sparing for National Health System. Moreover, as metformin has been shown to be largely 
safe in different sub-sets of population (as non-diabetic obese patients, pregnant women 
and fetuses, and diabetics affected by CKD, even in elderly), we do not envisage negative 
implications in ADPKD . 
 

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2.2 Investigational Products 
Metformin is a biguanide, able to forcedly activate AMPK (AMP dependent kinase),It is 
used in form of tablets orally administered to treat diabetes and insulin resistance. 
The mechanism of action of metformin is to acutely decrease hepatic glucose production, 
mostly through transient inhibition of the mitochondrial respiratory-chain complex 1, 
circulating insulin and intestinal glucose absorption, and improving peripheral tissue 
utilization of glucose, without causing hypoglicemia. 
The resulting decrease in hepatic energy status activates the AMP-activated protein 
kinase (AMPK), a cellular metabolic sensor, providing a generally accepted mechanism for 
metformin action on hepatic gluconeogenic activity. Direct, albeit transient and mild 
mitochondrial effects of metformin may explain theoretical risk of lactic acidosis in diabetic 
patients. 
Metformin is now indicated only for the treatment of Type 2 Diabetes Mellitus and no 
studies have been completed using metformin for the treatment of ADPKD in human, both 
“in vivo” and “in vitro”, nor the effect of metformin on glucose metabolism of non diabetic 
patients has been widely studied. 
Nonetheless a number of studies showed the existence of insulin resistance in ADPKD 
(14) and the same CKD induces insulin-resistance and causes Type 2 Diabetes Mellitus. 
Moreover, a large amount of evidences indicate that metformin is widely recognized for 
improving insulin resistance among patients affected by PolyCystic Ovary Syndrome (15) 
and that metformin may be safe also in non diabetic patients (16,17). 
Tolvaptan is a Vasopressin V2 receptor antagonist, mainly used (in form of tablets orally 
administered) to treat hyponatremia related to SIADH. It has been recently approved in 

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Italy for the treatment of ADPKD (Jinarc®) and in this trial Jinarc® will be used in 
accordance with its marketing authorization. 
2.2.1 Non-clinical Data 
Recently, new insights in ADPKD pathogenesis and therapy derived from some preclinical 
studies (7,18). They found that metformin stimulates AMPK, resulting in inhibition of both 
CFTR and mTOR pathways (that drive respectively intracystic fluid secretion e cell 
proliferation) and significant arrest of cystic enlargement in “in vitro” canine models and in 
“ex vivo” and “in vivo” murine models of renal cystogenesis. 
2.2.2 Clinical Data and Potential Risks and Benefits 
At this time, we have data from several clinical trials: three tested mammalian Target Of 
Rapamycin inhibitors (mTORi), one tested Octreotide-LAR, a long acting somatostatin 
analogue, and another tested Pravastatin. None of these drugs has been found effective in 
reversing or at least slowing its progression. 
Tolvaptan was clinically effective in delaying decline of renal function, as determined by 
changes in serum creatinine concentrations over 3 years, in an international, multicenter, 
clinical trial and in its open-label extension in subjects with CKD stage 1 to 3 due to 
ADPKD (19,20). Recently, Tolvaptan has been shown to be effective up to stage 4 (21). 
At the moment, Metformin is only indicated for the treatment of Diabetes Mellitus but it has 
been safely used in several clinical trials in non diabetic patients. Metformin is widely and 
safely used for the treatment of diabetes in CKD patients, but we have no clinical data 
regarding its efficacy in slowing disease progression in ADPKD, except those from 
retrospective analyses. 
Metformin in Pregnancy 

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Metformin easily passes through the placental filter, reaching therapeutic concentrations in 
fetal blood. 
Several trials have been conducted in order to evaluate metformin in non diabetic pregnant 
women affected by insulin resistance. 
The EMPOWaR (22) study enrolled 449 pregnant women aged over 16, who were 
randomized (1:1) to take Metformin (at a dose from 500 mg a day to 2500 mg a day) or 
placebo, since the 12th or 16th week of gestation till the end of gestation. Primary outcome 
of the study was the fetus weight at birth, secondary outcome was the Maternal Index of 
Insulin Resistance at the end of gestation. No statistical differences were observed 
between the two groups. Actually, follow-up of the newborns is ongoing. 
A British phase 2/3 trial (17) – NCT01273584 – enrolled 450 pregnant obese women 
(BMI>35) aged more than 18, between the 12th and the 18th gestational week. They were 
randomized (1:1) to be treated with Metformin (3000 mg a day) or placebo till the end of 
pregnancy. No differences were observed in newborns weight (primary outcome) and in 
fetal or neonatal adverse events incidence. Despite this, among pregnants treated with 
metformin there was a lower incidence of eclampsy. 
The Norwegian phase 3 trial (PregMet) (23) – NCT00159536 – enrolled 257 pregnant 
women, affected by PCOS (Polycistic Ovary Syndrome), during the first trimester of 
pregnancy. They were randomized (1:1) to take Metformin (2000 mg a day) or placebo. 
No differences were found in the primary outcome (a composite of gestational diabetes, 
eclampsia, preterm birth) nor in the fetal birth weight. Moreover, a post-hoc analysis of this 
study showed lower blood insulin levels in pregnant treated with metformin, but non 
difference was found in blood from fetal umbilical vein and artery, thus demonstrating that 
metformin does not influence glycemic control in non-diabetic healthy individuals (24). 

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In another study (25), 40 pregnant women affected by PCOS, some of whom affected by 
diabetes, were randomized (1:1) to receive Metformin (1700 mg a day) or placebo since 
19th week to delivery. No differences were found in terms of glucose homeostasis. 
A small randomized clinical trial (26) conducted in diabetic pregnants (treated both with 
metformin or insulin) showed that insulin blood levels are not able to influence metformin 
pharmacokinetic and OCT-2 mediated metformin transport.  
Metformin in Polycystic Ovary Syndrome (PCOS) 
PCOS is characterized by ovarian micro-polycistosis, hyperandrogenism, hirsutism, 
insulin-resistance. 
Recently, a clinical trial (27) randomize (1:1) 40 women affected by PCOS to take 
Metformina (1500 mg a day) or placebo for 3 months. Women treated with metformin had 
significantly lower blood pressure, but no differences were found in terms of glycemic 
control. 
Similarly, another phase 2 trial (28) – NCT00151411 – randomized (1:1) 114 women 
affected by PCOS to take Metformin (2000 mg a day) or placebo for six months and 
showed no differences in terms of insulin-sensitivity or glycemic control (secondary 
outcome). 
A British cross-over trial (29) conducted on 30 PCOS affected patients treated with 
Metformin or placebo, did not prove any advantage in terms of glycemic control but 
showed a better arterial stiffness and blood pressure control in women treated with 
metformin. 
Conversely, an Argentine trial (30) – NCT00679679 – showed that metformin treatment 
(1500 mg a day), if associated with a correct lifestyle, may improve glycemic control in 
women affected by PCOS, without differences in terms of adverse events. 

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Discrepancies between these studies may be explained by the post-hoc analysis of a 
cross-over trial (31), that metformin treatment seemed to influence glycemic control and 
insulin resistance only in obese women affected by PCOS, whilst no difference was found 
in incidence of adverse events. 
On the other hand, three other trials (32–34) revealed that metformin treatment in women 
affected by PCOS, even not obese, may improve insulin resistance, without causing 
adverse events. 
These evidences suggest that Metformin treatment in non diabetic individuals can not 
cause hypoglycemia, even if interfering on glycemic control, in a manner dependent on 
consistency of insulin resistance (35). 
Finally, a recent clinical trial conducted on women affected by PCOS (36) – NCT01389778 
– suggested that metformin may improve “Glucose Effectiveness”, that is the glucose 
capacity to stimulate itself uptake or to suppress itself production, under basal insulin 
levels. 
Metformin in Obesity 
Several randomized clinical trials conducted in non diabetic obese patients showed that 
metformin (at a dosage variable from 100 mg to 2000 mg a day), can improve insulin 
resistance compared to placebo, especially if associated with physical exercise, without 
causing hypoglycemia or severe adverse events (37–41). 
Metformin in Neoplastic disease 
Several clinical trials (mainly of phase 2) (42–55) explored the efficacy of metformin 
(compared to placebo) at different dosages, in addition to conventional chemotherapy. 
These studies were inconclusive in showing metformin efficacy in reducing tumoral cell 
proliferation and prolonging disease-free survival. Moreover, only one trial showed al little 

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increase of lactate production in tumor tissue, but none of them showed an increased 
incidence of Metformin Associated Lactic Acidosis (MALA) (56). 
Metfomin in CKD 
Currently metformin is widely used in diabetic patients affected by CKD, and consequently 
in ADPKD, nevertheless no study has been published directly evaluating this drug efficacy 
in slowing or possibly reverting ADPKD. 
The concerns over metformin and renal impairment arise from the perceived risk of lactic 
acidosis in such patients. Lactic acid is produced when there is tissue hypoperfusion with 
resulting hypoxia. The condition occurs when the production of lactate exceeds its 
metabolism and removal. Risk factors for lactic acidosis include sepsis, shock, myocardial 
infarction, cardiac, respiratory or hepatic failure and hypoxemia. 
Metformin associated lactic acidosis (MALA) has been reported, with a frequency ranging 
from 1 to 47 cases per 100,000 person years and a recent meta-analysis showed that the 
incidence of lactic acidosis wasn’t higher among patients treated with metformin compared 
to those treated with other antidiabetics (57). On the other hand, as the mortality rate is 
around 50% this is a feared complication (58). 
One study examined metformin levels in elderly patients with eGFR of 30-60 ml/min, or 
>60 ml/min, at doses of 850mg per day and 1700mg per day respectively. Metformin 
levels and plasma lactate levels were unchanged in both treatment groups, suggesting 
that metformin usage was safe in elderly patients with significant renal impairment (58). 
A recent large cohort study conducted in the USA attempted to quantify the association 
between metformin use and hospitalization with acidosis across the range of eGFR, 
accounting for change in eGFR stage over time.  

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In the primary cohort (n = 75 413), mean (SD) patient age was 60.4 (15.5) years, and 51% 
(n = 38 480) of the participants were female. There were 2335 hospitalizations with 
acidosis over a median follow-up of 5.7 years (interquartile range, 2.5-9.9 years). 
Compared with alternative diabetes management, time-dependent metformin use was not 
associated with incident acidosis overall (adjusted hazard ratio [HR], 0.98; 95% CI, 0.89-
1.08) or in patients with eGFR 45 to 59 mL/min/1.73 m2 (adjusted HR, 1.16; 95% CI, 0.95-
1.41) and eGFR 30 to 44 mL/min/1.73 m2 (adjusted HR, 1.09; 95% CI, 0.83-1.44). On the 
other hand, metformin use was associated with an increased risk of acidosis at eGFR less 
than 30 mL/min/1.73 m2 (adjusted HR, 2.07; 95% CI, 1.33-3.22). Results were consistent 
when new metformin users were compared with new sulfonylurea users (adjusted HR for 
eGFR 30-44 mL/min/1.73 m2, 0.77; 95% CI, 0.29-2.05), in a propensity-matched cohort 
(adjusted HR for eGFR 30-44 mL/min/1.73 m2, 0.71; 95% CI, 0.45-1.12), when baseline 
insulin users were excluded (adjusted HR for eGFR 30-44 mL/min/1.73 m2, 1.16; 95% CI, 
0.87-1.57), and in the replication cohort (adjusted HR for eGFR 30-44 mL/min/1.73 m2, 
0.86; 95% CI, 0.37-2.01). 
These results suggest that metformin use is associated with acidosis only at eGFR less 
than 30 mL/min/1.73 m2.  Caution should be exercised when using metformin in patients 
with type 2 diabetes and low eGFR (59). 
In conclusion, lactic acidosis seems to be a rare event in patients affected by CKD treated 
with metformin. Guidelines from the UK National Institute for Health and Clinical 
Excellence (NICE) and European Medicines Agency (EMA) suggests that metformin dose 
should be reduced by 1/3 at an estimated glomerular filtration rate (eGFR) of 45 ml/min (in 
this case avoiding a dosage greater than 1000 mg a day), and stopped at an eGFR of 30 
ml/min. 

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In this trial we decided not to associate metformin with tolvaptan, but to directly compare 
metformin versus the gold standard tolvaptan for the following reasons: 
- 
The “on-treatment” period has a duration of two years and, as showed by the 
TEMPO 3/4 trial (13), tolvaptan seems to be effective only after the first year of 
treatment; 
- 
The open label extension, the TEMPO 4/4 (20), showed that those patients still on 
tolvaptan after the first 3 years of treatment had kidney volume growth rate grater 
than those who received placebo during the first three years of the trial. On the 
other hand, no advantages were found in terms of eGFR declining rate in those who 
started tolvaptan later; 
- 
Even if rarely, tolvaptan treatment may cause liver injury, that may virtually increase 
the risk of MALA; 
- 
Tolvaptan, being an aquaretic drug, may cause dehydration and a virtual increase 
of the MALA risk; 
- 
Preclinical studies conducted in rodents models of diabetes insipidus induced with 
tolvaptan, indicate that metformin may significantly interfere with tolvaptan 
pharmacodynamics, thus limiting its effects. 
For all these reasons we can argue that metformin treatment, alone, may be safe and 
effective in slowing ADPKD progression, at the same extent of tolvaptan. If not, patients 
not receiving tolvaptan for two years, would not be detrimentally deprived of treatment, as 
tolvaptan starts to be effective after the first year, and its effects are not additional year by 
year (20). 
2.2.3 Pharmacokynetics and Pharmacodynamics 
Metformin has a poor oral bioavailability in the horse. Instead, oral bioavailability in the cat 
is similar to that in human. In fact, a dosage of 2 mg/Kg in the cat (equivalent to that 

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commonly used in human) allows to enrich therapeutic plasma levels (60). Furthermore, 
no pharmacokinetics differences have been found between diabetic and non diabetic cats, 
in whom metformin effects on glycemic control depend on basal insulin levels (61). 
Absorption  
After an oral dose of metformin, Tmax is reached in 2.5 h. Absolute bioavailability of a 500 
mg metformin tablet is approximately 50-60 % in healthy subjects. After an oral dose, the 
non-absorbed fraction recovered in faeces was 20-30 %. 
After oral administration, metformin absorption is saturable and incomplete. It is assumed 
that the pharmacokinetics of metformin absorption is non-linear. At the usual metformin 
doses and dosing schedules, steady state plasma concentrations are reached within 24-48 
h and are generally less than 1 µg/mL. In controlled clinical trials, maximum metformin 
plasma levels (Cmax) did not exceed 5 µg/mL, even at maximum doses. 
Food decreases the extent and slightly delays the absorption of metformin. Following 
administration of a dose of 850 mg, a 40 % lower plasma peak concentration, a 25 % 
decrease in AUC and a 35 min prolongation of time to peak plasma concentration was 
observed. The clinical relevance of this decrease is unknown. 
Distribution  
Plasma protein binding is negligible. Metformin partitions into erythrocytes. The blood peak 
is lower than the plasma peak and appears at approximately the same time. The red blood 
cells most likely represent a secondary compartment of distribution. The mean Vd ranged 
between 63 – 276 L. 
Biotransformation  
Metformin is excreted unchanged in the urine. No metabolites have been identified in 
humans. 

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Elimination  
Renal clearance of metformin is > 400 mL/min, indicating that metformin is eliminated by 
glomerular filtration and tubular secretion. Following an oral dose, the apparent terminal 
elimination half-life is approximately 6.5 h. When renal function is impaired, renal 
clearance is decreased in proportion to that of creatinine and thus the elimination half-life 
is prolonged, leading to increased levels of metformin in plasma. 
In humans, oral bioavailability of metformin does not differ between diabetics and non 
diabetics, nor between men and women; it is reduced by concomitant assumption of food 
and it does not proportionally increase as dosage increases (61). 
Plasma levels of metformin are mainly influenced by age and eGFR (62–64), than by OCT 
(Organic Cations Transporter) polymorphisms. In fact, Duong and coll. (63) have 
demonstrated that, in order to avoid MALA onset, metformin plasma levels have to be 
lower than 2,5 mg/l, thus it is useful to adapt metformin dosage to eGFR, avoiding to 
overcome these ratios: 500 mg of metformin if eGFR lower than 15 ml/min, 1,000 mg if 
eGFR <30 ml/min, 2,000 mg if <60 ml/min, 3,000 mg if <120 ml/min. 
Diuretics (65,66), even if able to induce eGFR reduction because of dehydration, are not 
able “per sè” to reduce metformin clearance, unlike proton pump inhibitors. As they block 
OCT (67). 
Even if metformin is excreted un-modified by the kidney, liver failure can itself reduce 
metformin excretion, thus increasing metformin toxicity (68). 
Metformin effects on glycemic control are directly proportional to basal glucose and insulin 
levels; in fact in healthy individuals metformin has no influence on fasting glucose levels, 
but significantly reduces after-meal insulin levels (69). 

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Metformin activates AMPK (AMP dependent Protein Kinase) in a dose dependent manner, 
thus causing forced inhibition of mTOR (mammalian Target of Rapamycin) and CFTR 
(Cystic Fibrosis Transmembrane conductance Regulator). 
Very recent published data suggests that the mechanism of action of metformin in vivo 
may involve pathways other than those related to AMPK. It is critically important to 
determine whether the potential therapeutic effects of metformin that has been identified in 
the context of ADPKD are due to its capacity to activate AMPK or are, instead, due to its 
effects on other targets.  
Recent research indicates that metformin can decrease cellular levels of cAMP. This is 
especially relevant in the setting of ADPKD because a substantial body of research has 
demonstrated that elevation of cAMP promotes cyst growth in vitro and in vivo. 
Furthermore, drug therapies that reduce cAMP are able to slow cyst growth both in mouse 
models of ADPKD as well as in human ADPKD patients (70). 
A recent paper from the group of Dr. Alessandra Boletta reported that cells homozygous 
for ADPKD-causing mutations feature substantial perturbations in energy production (71). 
These cells exhibit very high levels of glycolysis and low levels of oxidative metabolism, 
reminiscent of the Warburg effect that is seen in tumor cells. As a result of the very high 
levels of glycolysis the cytoplasmic levels of ATP are very high and levels of active AMPK 
are consequently very low. These data further support the idea that small molecule AMPK-
activators may have therapeutic benefit in ADPKD. 
2.2.4 Justification for the route of administration, dosage and dosage regimens 
Dose choice has been done on the basis of Takiar et al. study (7). They examined“in vivo”  
only one dose known to activate AMPK (daily i.p. injections of metformin 300 mg·kg−1·d−1 
dissolved in a 5% dextrose solution). When considered on a simple milligram per kilogram 
body weight basis, this dose appears considerably higher than the current maximum dose 

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prescribed for patients with diabetes or polycystic ovary syndrome. However, human-
equivalent dose extrapolation is calculated more accurately based on body surface area 
than on weight. When this calculation is performed for a 60-kg adult, the dose used in our 
mouse studies extrapolates to a daily dose of ~1,500 mg (7), well within the range in which 
metformin is safely used in humans. 
After oral administration, metformin absorption is saturable and incomplete. It is assumed 
that the pharmacokinetics of metformin absorption is non-linear. For this reason, a split 
doses regimen has been chosen for metformin administration (one cap every eight hours). 
Patients randomized to tolvaptan, will start the treatment according to AIFA indications (45 
mg followed, 8 hours later, by 15 mg), then they will up-titrate (every week, if tolerated) to 
60 mg + 30 mg and then to 90 mg + 30 mg. 
Patients on metformin, will start to take metformin once a day (500 mg), between meals. 
Every week they will up-titrate to 500 mg twice a day (if tolerated) and then to 500 mg 
thrice a day. 
 
2.3 Rationale of the study 
Renal cyst development and expansion in ADPKD involves both fluid secretion and 
abnormal proliferation of cyst-lining epithelial cells. The chloride channel of the cystic 
fibrosis transmembrane conductance regulator (CFTR) participates in secretion of cyst 
fluid, and the mammalian target of rapamycin (mTOR) pathway may drive proliferation of 
cyst epithelial cells. CFTR and mTOR are both negatively regulated by AMP-activated 
protein kinase (AMPK). Metformin, a drug widely used, is a pharmacological activator of 
AMPK. We found that metformin stimulates AMPK, resulting in inhibition of both CFTR and 
the mTOR pathways. Metformin induces significant arrest of cystic growth in both in vitro 

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and ex vivo models of renal cystogenesis. In addition, metformin administration produces a 
significant decrease in the cystic index in two mouse models of ADPKD. These results 
suggest a possible role for AMPK activation in slowing renal cystogenesis as well as the 
potential for therapeutic application of metformin in the context of ADPKD. 
Currently three randomized clinical trial are evaluating Metformin effectiveness in slowing 
ADPKD progression. 
A phase II, double-blinded randomized placebo-controlled trial (“TAME” study – 
NCT02656017) of 26 months duration will include non diabetic adults (n = 96) aged 18-60 
years, with an eGFR ≥50 mL/min/1.73 m2 and ADPKD, recruited from university-based 
practices in Baltimore and Boston. Participants will be randomized in 1:1 ratio to metformin 
or placebo at 500 mg once daily, increased every 2 weeks to a maximum of 1,000 mg 
twice daily as tolerated. Dose is decreased if eGFR falls to 30-45 mL/min/1.73 m2 and 
discontinued at eGFR < 30 mL/min/1.73 m2. 
The primary outcomes are safety, assessed by the rates of hypoglycemia, elevated lactic 
acid levels, adverse events, and tolerability assessed by the Gastrointestinal Severity 
Rating Scale and maximum tolerated dose of study medication. Secondary outcomes 
include changes in total kidney and liver volumes, pain, and health-related quality of life, 
and changes in urinary metabolomics biomarkers (72). 
Another phase II double-blinded randomized placebo-controlled trial – NCT02903511 –of 
12 months duration will include non diabetic adults (n = 50) aged 30-60 years, with an 
estimated glomerular filtration rate (eGFR) between 50-80 mL/min/1.73 m2 and ADPKD, 
recruited from university-based practices in Denver. Participants will be randomized in 1:1 
ratio to metformin or placebo at 500 mg once daily, increased every 2 weeks to a 
maximum of 1,000 mg twice daily as tolerated. 

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The primary outcomes are safety, assessed as percentage of participants who at the end 
of 12 months are still prescribed the full-randomized dose of metformin, and the 
percentage of participants who are prescribed at least 50% of the randomized dose. 
Secondary outcomes include changes in total kidney volume measured by MRI at baseline 
and 12 months, Change in kidney function calculated from serum creatinine 
measurements at baseline and after 3, 6, 9 and 12 months, Rate of Serious Adverse 
Events (73). 
Moreover a Dutch cross-over clinical trial will evaluate metformin efficacy in attenuating 
aquaretic effects of tolvaptan (74) 
 
2.4 Population of the Study 
This trial will enroll approximately 150 tolvaptan and metformin naïve subjects affected by 
Type I-truncating ADPKD, as they have grater probability of progression (10). Moreover 
data from Tempo trials (3/4 and 4/4) (19,75) and from its post-hoc analysis (76) revealed 
that patient with faster disease progression had greater beneficial effects from therapy. 
Male and female adults will be enrolled, from 18-50 years of age with eGFR greater than 
45 ml/min/1,73 m2 
The study will be conducted in 11 Hospital Nephrology Departments. Patients will be 
selected from local databases and subjects will be enrolled till the estimated sample size is 
achieved. 
Only subjects tolerating a run-in period of tolvaptan or metformin will enter the on-
treatment period, in order to limit subsequent withdrawal due to lack of tolerability. 
 

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3. OBJECTIVES 
Objective of the study is to assess if a two-year course of 1500 mg oral metformin is 
effective and safe in treatment of ADPKD, as compared to the actual gold-standard 
therapy, tolvaptan (Jinarc®). 
3.1 Primary objectives 
Currently, drugs’ efficacy in ADPKD has been evaluated by means of eGFR and TKV 
variations. In ADPKD, kidney function may remain preserved until the 4th to 6th decade of 
life, when advanced renal cystic involvement has occurred. In fact, measured GFR is a 
poor marker of disease severity and progression, especially in early phases, when it is 
preserved through compensatory hyperfiltration during a prolonged period (typically 
decades), but eventually declines sharply. Despite this, to date, eGFR remains the 
standard to assess kidney function in randomized clinical trials in ADPKD. By contrast, 
TKV in relation to age can identify patients with progressive disease. TKV is an accurate 
estimate of kidney cyst burden and associates with pain, hypertension, gross hematuria, 
proteinuria or albuminuria, and loss of kidney function. TKV increases exponentially in 
virtually every ADPKD patient, with an average of 5–6%/year in adults.  Elevated TKV, 
particularly when used together with age and kidney function, identifies individuals who are 
at higher risk for progression to ESRD. Precise measurement of TKV is necessary in 
clinical trials to assess the impact of therapeutic interventions over short periods of time 
and can be obtained by planimetry or stereology analysis of CT images. 
 
3.2 Secondary objectives 
Main secondary objective is to assess metformin efficacy (as compared to tolvaptan) in 
reducing the increase of TKV. 

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Moreover, it will be evaluated the rate of onset of metformin and tolvaptan related Adverse 
Events (AEs) namely Metfromin Associated Lactic Acidosis (MALA) and Acute Liver Injury 
(ALI), respectively. 
 
4. TRIAL DESIGN 
This is a phase 3a, independent, multi-centre, parallel arms, randomized controlled trial 
comparing efficacy and safety of metformin and tolvaptan in ADPKD. The overall design is 
illustrated in figures 1,2,3,4. 
Each investigator has both ethical and legal responsibility to ensure that subjects being 
considered for inclusion in this trial are given a full explanation of the protocol and of their 
role and responsibilities in the proposed research. This will be documented on a written 
ICF that shall be approved by the same institutional review board/independent ethics 
committee (IRB/IEC) responsible for approval of this protocol. In addition, the protocol 
explanation may include recorded or electronic means of education, which will also meet 
IRB/IRC approval. Each ICF will include the elements required by the International 
Conference on Harmonization (ICH) Good Clinical Practice (GCP) Guideline and local 
regulatory requirements and must adhere to the ethical principles that have their origin in 
the Declaration of Helsinki. Subject insurance and the publication policy for the trial will be 
provided and documented according to DM 14 Luglio 2009. 
Written informed consent will be obtained from all subjects (or their guardian or legal 
representative, as applicable for local laws). Investigators may discuss the availability of 
the trial and the possibility for entry with a potential subject without first obtaining consent. 
However, informed consent must be obtained and documented prior to initiation of any 
procedures that are performed solely for the purpose of determining eligibility for this trial, 

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including withdrawal from current medication(s). When this is done in anticipation of, or in 
preparation for, the research, it is considered to be part of the research. 
Once the appropriate essential information has been provided to the subject and fully 
explained in layman’s language by the investigator (or a qualified designee) and it is felt 
that the subject understands the implications of participating, the IRB/IEC-approved written 
ICF shall be personally signed and dated by both the subject and the person obtaining 
consent (investigator or designee), and by any other parties required by the IRB/IEC. The 
subject shall be given a copy of the signed ICF; the original shall be kept on file by the 
investigator. All of the above mentioned activities must be completed prior to the subject’s 
participating in the trial. Every phase of the trial will be conducted in compliance with the 
protocol, GCP and the applicable regulatory requirement. 
The trial contemplates a 2 weeks screening period (included in a 9 months total 
recruitment period) during which 3 visits have to be collected (the 1st and the 2nd in three 
days, and the 3rd after biochemical analyses performed during the first two visits have 
been reviewed). The subject’s eligibility for the trial will be confirmed by the mean of eGFR 
calculated from the 2 pre-treatment, central-lab, serum creatinine assessments. Longer 
screening periods (up to 4 additional weeks) are acceptable for subjects needing 
stabilization after changing or discontinuing other treatments, especially anti-hypertensives 
and diuretics. In this case Subjects must sign ICF and then agree to be switched to an 
alternate form of therapy in order to be eligible. As part of this stabilization or wash-out 
period different lab safety tests may be performed. Subjects who fail to meet trial 
requirements during the screening period may be rescreened at a later date. 
Once eligibility is assessed, patients will undergo non-contrast enhanced CT-scan of 
kidneys (if not performed within six months prior to randomization). 

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Randomization visit will occur on Day -29. During this visit patients will be randomized (in 
a ratio 1:1 tolvaptan:metformin) to each arm of treatment and will start an IMP titration 
period (3 weeks from -28 to -8). Subjects not tolerating the minimum IMP dose will be 
considered “Titration failures” and will complete End of Treatment (EoTx) visit 
assessments and will be followed up after 7 days by phone call to assess any ongoing 
AEs. Subjects tolerating the minimum IMP dose enter the unblind run-in period (1 week 
from Day -7 to -1). During the “Run-in” phase, subjects will continue on a stable IMP dose 
to confirm tolerability over a longer period. At the end of the run-in period (Day -1), 
subjects not tolerating the minimum IMP dose will be considered “Run-in failures” and will 
complete EoTx visit assessments and will be followed up after 7 days by phone call to 
assess any ongoing AEs. Subjects completing the run-in will start the open-label 24 
months treatment period, during which visits will be collected three-monthly. At the end 
of the 24th month, and in case of early treatment cessation, follow-up period (3 weeks 
from +8 to +21) will start, during which 2 visits have to be collected. No IMP will be 
administered during this period. 
Assessments at the Randomization (Day -29), End of IMP Run-in Period (Day -1), End of 
each three-monthly of on-therapy period will include those for points 2 to 8 of screening 
period plus IMP dispensation. 
Assessments during EoTx Visits (in case of Titration failure, Run-in failure, early treatment 
cessation) and Follow-up visits will include those for points 2 to 8 of screening period. Non 
contrast enhanced CT-scan of the kidneys for TKV measurement will be also performed at 
the end of Month 24. 
Patients treated with tolvaptan, will anyhow undergo monthly visits during the first 18 
months of therapy (as prescribed by the additional monitoring requested by AIFA), then 
every three months. 

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4.1 Screening Period (up to Day -30) 
No investigational treatments will be administered during the screening period. 
Preliminary eligibility for the trial will be initially assessed using the subjects’ historical 
laboratory or imaging data.  
During this period, the subject’s eligibility for the trial will be confirmed using historical 
genetic test data and imaging data of the kidneys to support a diagnosis of ADPKD and to 
verify the level of CKD primarily due to ADPKD and not to other renal (hypoplasia) or 
metabolic (diabetic or hypertensive nephropathy) disorders. 
Eligibility will be confirmed by the mean of eGFR calculated from the subjects’ 2 pre-
treatment, central-lab, serum creatinine assessments (collected at least 24 hours apart). 
The final screening visit on Day -29 will not be scheduled until laboratory results from the 
second screening visit (V2) are received and evaluated. The eGFR values will be 
estimated based on the Chronic Kidney Disease-Epidemiology (CKD-EPI) formula. 
Subjects will be told that they will receive tolvaptan or metformin during the subsequent 
periods of the trial. 
On Day -30, patients will undergo TKV measurement by means of Ct- or MRI-scan (if not 
already performed within the 6 months before the enrollment). Then, patients will be 
randomized to receive either metformin or tolvaptan and they will be told to start IMP 
assumption since the day after randomization. 
Those randomized in metfromin arm will receive Zuglimet® 500 mg (2 packages, each of 
them containing 3 blisters; every blister contains ten 500 mg coated tablets). 

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Those randomized to tolvaptan arm will receive Jinarc® 45/15 mg (2 packages, each of 
them containing 4 blisters; every blister contains seven 15 mg tablets of and seven 45 mg 
tablets). 
The screening period will last 1-2 weeks, but may be extended up to an additional 8 weeks 
for subjects who require modification of medical care or further medical evaluation 
specifically for this trial. This may include, for example, stabilizing anti-hypertensive 
regimens for subjects discontinuing diuretics or “wash-out” of other investigational agents.  
 
4.2 Randomization visit (Day -30) 
Randomization process will be carried out by a WEB-based, internet-accessible, system 
(e-trial platform). Investigators willing to include a patient should log-in into the e-trial 
platform and complete the registration form. 
The patient allocation number and the treatment arm will be immediately TRASMITTED on 
line without blinding. 
Any controversial eligibility assessment will be discussed with the Study Chair. 
Each patient will be informed via a cover letter including clear instructions on participation, 
drug use, dosing and prescription. 
Randomization visit may coincide with CT-scan visit.  
 
4.3 IMP Titration Period (since Day -28 up to Day -8) 
Subjects randomized in tolvaptan arm will be given a split dose of 45/15 mg tolvaptan 
(unblind) with upward titration every 7 days to 45/15 mg, 60/30 mg, up to a maximum dose 

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of 90/30 mg per day over 3 weeks. Jinarc® has to be taken between meals; the first dose 
upon waking and the second dose after eight hours from the first. 
Dose up-titration will be done after tolerability check (by phone call the patient will be 
asked: “Are you having troubles taking this drug? Are you able to tolerate this dose for the 
rest of your life?”). Up-titration will be done the day after tolerability check, in Day -22 and 
in Day -15. 
Subjects who are unable to tolerate at least 45/15 mg of daily tolvaptan will be considered 
“Run-in failures” and will complete an EoTx visit and be followed up after 7 days by phone 
call to assess any ongoing AEs.  
Subjects randomized to metformin arm will be given a single dose of 500 mg of metformin 
for the first week (unblind), then a split dose of 500/500 mg metformin with upward titration 
after 7 days to 500/500/500 mg, (that is the maximum trial dose of metformin per day). 
Zuglimet® has to be taken between meals; the first dose upon waking, the second and the 
third daily dose after eight hours from the previous dose. 
Dose up-titration will be done after tolerability check (by phone call the patient will be 
asked: “Are you having troubles taking this drug? Are you able to tolerate this dose for the 
rest of your life?”). Up-titration will be done the day after tolerability check, in Day -22 and 
in Day -15. 
Subjects who are unable to tolerate at least 500/500 mg of daily metformim will be 
considered “Run-in failures” and will complete an EoTx visit and be followed up after 7 
days by phone call to assess any ongoing AEs. Subjects tolerating the minimum IMP dose 
will enter the unblind run-in period (1 week from Day -7 to -1). 
Assessments during up-titration phone call will include: 
1) Assess IMP tolerability 

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2) Assess AEs, if reported  
 
4.4 IMP Run-in Period (since Day -7 up to Day -1) 
Subjects tolerating at least 45/15 mg tolvaptan or 500/500 mg metformin may enter the 
unblind, run-in period (1 week duration). Subjects will continue on a stable IMP dose to 
confirm tolerability over a longer period. 
At the end of the run-in period, subjects not tolerating at least 45/15 mg tolvaptan or 
500/500 mg metfromin will be considered “Run-in failures”. They will complete EoTx visit 
assessments and be followed up after 7 days by phone call to assess any ongoing AEs. 
Subjects found ineligible to be randomized and continue in this trial must have a 7-day 
follow-up visit. 
 
4.5 Unblind Treatment Period (Day 0 to Month 24) 
Only subjects completing the IMP run-in period tolerating at least 45/15 mg of tolvaptan 
and 500/500 mg of metformin will be allowed upon entry to this unblind period.  
In the metformin arm, during the treatment period visits will be scheduled every 3 months 
(each month has 28 days duration), within 3 days of the end of the trimester.  
In tolvaptan treated patients, visits will be performed every month for the first 18 months, 
then every three months (each month has 28 days duration), within 3 days of the end of 
the month or the trimester (as prescribed by the additional monitoring requested by AIFA). 
Beside the clinic visit and dispensing new bottles of IMP, subjects will have blood drawn 
on the last day of this period for efficacy and safety measures. 

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The treatment duration of these subjects will be 24 months from the end of IMP run-in. 
Subjects not continuing in this trial will complete EoTx visit assessments and be followed 
for 7 days to assess any ongoing AEs. 
From that point forward, every effort to maintain adherence and continuation of the 
subjects until the end of the trial should be undertaken. If continued tolerability becomes 
an issue, subjects may temporarily interrupt treatment as needed. 
All subjects have the right to withdraw their consent from further participation in the trial at 
any time without prejudice. 
Regardless of discontinuation of IMP, the subjects are expected to complete all monthly 
visits and assessments including the Month 24 visit. 
 
4.6 Follow-up Period (up to Day +21 since Month 24 or End of Treatment) 
Randomized subjects will enter the follow-up period after they complete the unblind, 
randomized treatment period, or after their EoTx visit, if they discontinued IMP. The follow-
up period will be for 21 days in duration. 
There will be no scheduled visits/assessments during the first week of the follow-up period. 
After the first week, 2 visits should be scheduled during the remaining 2 weeks of the 
follow-up period (between Day +8 and Day +21). The first visit should be scheduled on 
approximately Day +8, the second visit on approximately Day +21. These visits will be 
clinic visit. 
 
4.7 End of Treatment End of Trial 

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The end of trial date is defined as the last date of last contact with the subject. This does 
not refer to overall trial duration. The end of trial date and timing for follow-up assessments 
will be individualized for each subject. 
Randomized subjects will have their last scheduled treatment 25 months from their date of 
randomization. If a subject discontinues IMP before Month 25, the last date that the 
subject received IMP will be recorded as EoTx.  
 
4.8 Measures to Minimize/Avoid Bias 
Only subjects who reach Day -1 and are who have indicated that they would likely be able 
to tolerate the minimum dose of IMP “for the rest of their lives” at a level of 45/15 mg for 
tolvaptan and of 500/500 mg for metformin will be eligible to enter the un-blind, 
randomized treatment period. 
Immediately prior to randomization, and at all subsequent visits or site-subject contacts, 
the subject will be reminded of the importance of their commitment to continue 
participation in the trial. 
Randomization will be 1:1, tolvaptan:metformin. Randomization process will be carried out 
by a WEB-based, internet-accessible, system (e-trial platform). Investigators willing to 
include a patient should log-in into the e-trial platform and complete the registration form. 
 
Each patient will be informed via a cover letter (that is the informed consent form) including 
clear instructions on participation, drug use, dosing and prescription. 
 

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5. POPULATION OF THE STUDY 
5.1 Number of Subjects and Sites 
This trial will enroll approximately 150 tolvaptan and metformin naïve subjects affected by 
Type I-truncating ADPKD, as they have grater probability of progression (10). Moreover 
data from Tempo trials (3/4 and 4/4) (19,75) and from its post-hoc analysis (76) revealed 
that patient with faster disease progression had greater beneficial effects from therapy. 
Male and female adults will be enrolled, from 18-50 years of age with eGFR greater than 
45 ml/min/1,73 m2 
The study will be conducted in about 11 Italian Hospital Nephrology Departments. Patients 
will be selected from local databases and subjects will be enrolled till the estimated sample 
size is achieved. Only subjects tolerating a run-in period of tolvaptan or metformin will 
enter the on-treatment period, in order to limit subsequent withdrawal due to lack of 
tolerability. 
 
5.2 Inclusion Criteria 
1) Men and women aged between 18 and 50 years 
2) eGFR (CKD-EPI) ≥ 45 ml/min/1,73 m2 
3) Genetic Diagnosis of Type I ADPKD truncating mutation 
4) Signed and dated informed consent 
 
5.3 Exclusion Criteria 
1) Women of childbearing potential (WOCBP) who do not agree to practice 2 different 
methods of birth control or remain abstinent during the trial and for 30 days after the last 

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dose of IMP. If employing birth control, 2 of the following precautions must be used: 
vasectomy of partner, tubal ligation, vaginal diaphragm, intrauterine device, birth control 
implant, condom, or sponge with spermicide. Non-childbearing potential in women is 
defined as female subjects who are surgically sterile (ie, have undergone bilateral 
oophorectomy or hysterectomy) or female subjects who have been postmenopausal for at 
least 12 consecutive months.  
2) Women who are breast-feeding and/or who have a positive pregnancy test result prior 
to receiving investigational medical product (IMP).  
3) Treatment with acarbose, guar gum, cimetidin, phenprocoumon, oral anticoagulants, 
thrombolytic drugs, diuretics, ranolazin, cephalexin.  
4) Evidence of active systemic or localized major infection at the time of screening.  
5) Hepatic impairment or liver function abnormalities other than that expected for ADPKD 
with typical cystic liver disease during the screening period as defined by: 
o AST O ALT >8x UNL  
o AST O ALT >5x UNL >2 WEEKS 
o AST O ALT >3x UNL E BT >2x UNL OR INR >1,5  
o AST O ALT >3x UNL E SIGNS AND SYMPTOMS OF LIVER DAMAGE 
(fatigue, anorexy, nausea, vomiting, right hypocondrium pain, fever, jaundice, 
skin rash, itching) 
6) Acute or chronic disease causing tissue hypoxia (e.g.: myocardial failure, severe 
arythmias, myocardial infarction, respiratory failure, liver failure, alcohol acute intoxication, 
alcoholism, dehydration). 
7) Previously diagnosed diabetes already in treatment with other hypoglycemic drugs. 

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8) Ongoing breast feeding.  
9) Use of any other investigational drug or treatment up to 4 weeks before enrollment and 
during the treatment phase. 
10) Known hypersensitivity to metformin and its derivatives. 
11) Psychiatric disorders and any condition that might prevent full comprehension of the 
purposes and risks of the study.  
12) Malignancies within three years before enrolment in the study.  
13) HIV, HBV, HCV infection. 
14) Urinary tract obstruction. 
 
5.4. Withdrawal of Consent 
All subjects have the right to withdraw their consent from further participation in the trial at 
any time without prejudice. The investigator can also discontinue a subject’s participation 
in the trial at any time if medically necessary. Unless the subject provides their written 
withdrawal of consent or there is other written documentation by the investigator 
confirming the subject’s verbal intent to completely withdraw from the trial, subjects should 
be followed for all protocol-specified evaluations and assessments. 
Complete withdrawal of consent requires a subject’s refusal also of all of the methods of 
follow up. 
Withdrawal of consent is a critical trial event and therefore should be approached with the 
same degree of importance and care as is used in initially obtaining informed consent. The 
reasons for a subject’s intended withdrawal need to be completely understood, 
documented and managed to protect the rights of the subject and the integrity of the trial.  

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A subject may initially express his desire to interrupt or discontinue IMP administration, 
which is not equivalent to a complete withdrawal of consent for further participation.  
A subject may, however, indicate that further trial participation is creating a burden on their 
work or social schedule. Therefore, the investigator should determine if the subject can 
continue participation in the trial if modifications to his/her treatment and/or schedule of 
assessments can be accommodated. 
Only subjects who withdraw their permission for all of the above degrees of follow-up are 
considered to have completely withdrawn their consent to participate in the study. 
In all cases of impending IMP discontinuation or consent withdrawal, investigators will be 
given instructions to meet and discuss with the subject their options of continuing in the 
trial, preferably on therapy. The investigator should ensure understanding and 
documentation of the reasons for the subject’s desire to withdraw consent. 
If a subject in randomized treatment period wishes to withdraw from the trial: 
The investigator should first seek to understand the subject’s motivation and wherever 
possible make accommodations to prevent treatment discontinuation or complete 
withdrawal of consent and maintain the fullest compliance with  
1. Participation in a subset of protocol specified follow-up procedures (by a frequency 
schedule and method as agreed by subject and staff). 
2. Participation in all regularly scheduled, study-related follow-up visits and EoTx 
visits. 
3. Contact of the subject by trial personnel, even if only by telephone, to assess 
current medical condition and obtain necessary medical or laboratory reports 
relevant to the trial’s objectives. 

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4. Contact of alternative person(s) who have been designated in source records as 
being available to discuss the subject’s medical condition, even if only by 
telephone, mail or e-mail (e.g., family, spouse, partner, legal representative, friend, 
neighbor, physician). 
5. Access to medical information from alternative sources (e.g., hospital/clinic 
medical records, referring doctor’s notes, public records, dialysis, transplantation 
or vital registries, social media sources). 
 
6. TREATMENT 
6.1 Treatment dose and schedule 
Subjects will be instructed to take the following doses for titration: 
- 
1 tablet 45 mg upon waking and 1 tablet 15 mg approximately 8 to 9 hours later for 1 week; 
- 
1 tablet 45 mg + 1 tablet 15 mg upon waking and 2 tablets 15 mg approximately 8 to 9 
hours later for 1 week; 
- 
2 tablets 45 mg upon waking and 2 tablets 15 mg approximately 8 to 9 hours later for 1 
week. 
During run-in period, subjects will take the maximum dose of tolvaptan achieved during 
titration (or at least 45/15 mg). 
For the Metformin titration period and subsequent run-in period, subjects will receive 2 
packages at the first visit of metformin 500 mg. 
Subjects will be instructed to take the following doses for titration: 
- 
1 tablet 500 mg upon waking for 1 week; 
- 
1 tablet 500 mg upon waking and 1 tablet 500 mg approximately 8 to 9 hours later for 1 
week; 

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- 
1 tablet 500 mg upon waking, 1 tablet 500 mg approximately 8 to 9 hours later and 1 tablet 
500 mg approximately 8 to 9 hours later for 1 week. 
During run-in period, subjects will take the maximum dose of metformin achieved during 
titration (or at least 500/500 mg). 
If the subject cannot tolerate the lowest permitted doses, he/she will be deemed a titration 
failure or a run-in failure. 
During the on-treatment period, the patient will take the maximum tolerated dose achieved 
during titration and run-in. The subject will stay on that dose for the entire trial, if not 
otherwise contraindicated by AEs or not tolerated. 
Patients on metformin experiencing eGFR reduction below 45 ml/min, can not take more 
than 1000 mg a day of metformin (thus reducing from 1500 mg a day to 1000 mg a day). 
Those patients on Jinarc will receive 1 package containing 4 blisters (irrespectively of the 
dosage). 
Those patients on Zuglimet will receive 2 packages (all containing 3 blisters of 10 tablets) 
if on 500/500 mg a day, 3 packages if on 500/500/500 mg a day. 
 
6.2 Investigational product 
6.2.1 Investigational product description 
Tolvaptan is provided as tablets. Metformin is provided as coated tables. 
6.2.2 Packaging and labeling 
All IMP will be provided to the investigator(s) by the promoter of the Coordinating Center or 
designated agent. 
Tolvaptan (Jinarc®) will be provided as 3 types of packages: 

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1) package containing 4 blisters of tolvaptan. Each blister contains 14 tablets: 7 15 mg 
tablets (triangular, in a green background), and 7 45 mg tablets (squared, in a gray 
background); 
2) package containing 4 blisters of tolvaptan. Each blister contains 14 tablets: 7 30 mg 
tablets (rounded, in a purple background), and 7 60 mg tablets (rectangular, in a golden 
background); 
3) package containing 4 blisters of tolvaptan. Each blister contains 14 tablets: 7 60 mg 
tablets (rectangular, in a golden background); and 7 90 mg tablets (pentagonal, in an 
orange background). 
Metformin (Zuglimet®) will be provided as a package containing 3 blisters. Each blister 
contains 10 500 mg tablets. 
Each package used will be labeled to clearly disclose the subject identification number 
(ID), compound ID, trial number, Promoter's name and address, instructions for use, route 
of administration. 
Each package of the designated IMP will be dispensed at the beginning of each specific 
period. 
For the tolvaptan titration period and subsequent run-in, subjects will receive 2 cartons at 
the first visit of tolvaptan 45/15 mg.  
6.2.3 Storage Conditions 
All IMPs will be stored in a securely locked cabinet or enclosure. Access will be limited to 
investigators and their designees.  Neither investigators nor any designees may provide 
IMP to any subject not participating in this protocol. 

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The IMP should be stored according to the conditions specified in the IMP label. The 
clinical site staff will maintain a temperature log in the drug storage area recording the 
temperature at least once each working day. 
6.2.4 Administration Method 
IMP will be distributed to the patient during each visit it is expected drug dispensation. 
Patient will orally take IMP at home. 
6.2.5 Treatment of Overdose 
In case of overdose, the subject will be instructed to interrupt IMP assumption, skipping 
the same number and type of doses he has over-assumed.  
If the patient has assumed twice the scheduled maximum daily dose, it also will be 
reported as IRE. An out of protocol visit has to be scheduled and the subject will undergo 
blood withdrawal in order to assess any AEs. IMP assumption can be restarted if no AE 
has arisen. 
6.2.6 Retrieval and/or Destruction 
The investigator or designee must maintain an inventory record of IMP received, 
dispensed, administered, and returned. 
Upon completion or termination of the trial, all unused and/or partially used IMP must be 
returned to the sponsor or a designated agent. 
All IMP returned to the sponsor must be accompanied by appropriate documentation and 
be identified by protocol number with trial site number on the outermost shipping container.  
Returned supplies should be in the original containers. The assigned trial monitor will 
facilitate the return of unused and/or partially used IMP. 
6.3 Prohibited medications and dietary restrictions 

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Medications or surgical therapies used for the purpose or potential for modifying the 
progression of PKD cyst growth or development will be prohibited. These include, but are 
not restricted to, somatostatin agonists, rapamune (sirolimus), anti-sense ribonucleic acid 
(RNA) therapies, vasopressin antagonists, (mozavaptan), Vaprisol (conivaptan), or 
agonists (e.g., desmopressin) and cyst decompression surgery. 
Continuous or short-term use of other medications, while not prohibited, may be restricted 
by the investigator because of their potential for interference with metabolism or efficacy 
endpoints. This includes the use of diuretics which may be used intermittently. Diuretics 
are not generally recommended in ADPKD due to their tendency to increase AVP levels 
through relative dehydration or volume depletion; thus, chronic use of diuretics (e.g., for 
hypertension) will be prohibited due to potential endpoint interference and is an 
exclusionary criterion for this trial. Subjects taking such agents must first sign an ICF and 
then agree to be switched to an alternate form of therapy in order to be eligible for the trial. 
Some drugs are known to alter creatinine concentrations so, while not prohibited, subjects 
should alert their trial doctor, and any other health-care providers, to take this into 
consideration when considering changes in their prescribed or over-the-counter 
medications. A brief list would include: cimetidine, NSAID medications like aspirin or 
ibuprofen, chemotherapy drugs, and cephalosporin, RAAS blockage, acarbose, guar gum, 
phenprocoumon, oral anticoagulants, thrombolytic drugs, ranolazin, cephalexin. 
Since tolvaptan is a weak cytochrome P450 (CYP) 3A4 substrate, potent CYP3A4 
inhibitors should be avoided during the trial, with the exception of amiodarone, which was 
found to have no effect on tolvaptan. A partial list of other CYP3A4 inhibitors include 
pomelo, grapefruit, or Seville orange and drugs listed in table 1. 
Restriction of excess dietary sodium and cooked meat protein may prove beneficial to 
subjects with a history of, or predisposition for, hypertension or kidney disease in general 

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and should be applied to all subjects diagnosed with advanced ADPKD, particularly if there 
is evidence for a tendency towards rapid progression.  In the absence of alternate regional 
practices, restrictions of dietary salt < 5g/day and dietary cooked meat protein < 1 g/kg/day 
and to limit caffeinated drinks/foods should also be given (no more than 2 coffee 
equivalents per day). 
Additionally, fluid intake is generally encouraged in subjects with PKD.  Given the potential 
for dehydration with tolvaptan treatment, all subjects should be instructed to ingest fluids in 
anticipation of, or at the first sign of thirst in order to avoid excessive thirst or dehydration.  
Upon consent, all subjects should receive the recommendation to ingestion of at least 2-3 
liters of fluid (including in solid, semi-solid, and liquid foods) per day, unless otherwise 
directed by your study doctor. This recommendation should start during screening and 
continue through the end of the trial.  Additionally, subjects should ingest 1 to 2 cups of 
water before bedtime regardless of perceived thirst and replenish fluids overnight with 
each episode of nocturia. Dehydration will be monitored by subject self-assessment of 
changes in body weight and reporting of symptoms.  Acute changes of > 3% of body 
weight (increase or decrease) over any 7-day period should be noted.  
 
7. STUDY DURATION 
7.1 Study Duration  
The trial has a 36 months overall duration, that include a 9 months recruitment period. 
7.1.1 Screening Period:  
Has a 2 weeks duration, it is included in the 9 months recruitment period. 
7.1.3 Treatment Period: 

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It has a 25 months duration. Each month lasts 28 days. It includes the 3 weeks titration 
period and the 1 week run-in period. 
7.1.4 Post-Treatment Follow-up Period: 
It lasts 21 days. 
7.1.4 Total Study Duration:  
About 3 years. 
 
8. STUDY ENDPOINTS 
Trial endpoints were constructed based on advice obtained at scientific advisory boards 
and meetings with regulatory agencies from Japan, EU and the USA and were chosen to 
represent potentially clinically meaningful changes in levels of laboratory or physiological 
parameters and patient symptoms reasonably expected to develop or worsen with 
progressive ADPKD. 
8.1 Effectiveness Endpoints 
8.1.1 Primary Endpoint 
Primary outcome of the study is to evaluate the difference between Metformin and 
Tolvaptan in annualized slope of eGFR (CKD-EPI) for individual subjects, that will be 
calculated 
using 
an 
appropriate 
baseline 
and 
post-randomization 
assessment. 
Traditionally, the primary endpoint in trials testing renoprotective effects of interventions 
has been the incidence of ESRD or doubling of serum creatinine, which correlates to a 
57% reduction in eGFR. Of note, ADPKD is a relatively slowly progressive disease. In a 
population such as that of the TEMPO 3:4 trial, which was selected to have early-stage 
ADPKD (eGFR >60 mL/min), it cannot be expected that this endpoint will occur within the 
typical duration of a renal trial. Adopting this endpoint would therefore only pick up cases 

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of acute kidney injury and not be of help for studying the effect of interventions on 
progression of the disease itself. To stimulate progress in developing renoprotective 
agents, especially for studies in early-stage CKD and diseases that are relatively slow in 
progression, the nephrological community has pleaded for the use of alternative endpoints 
for renal trials, namely lesser declines in eGFR. Regulatory authorities have accepted this 
proposal. When studying the incidence of a 25% reduction in eGFR [a priori defined in the 
TEMPO 3:4 trial and accepted by the European Medicines Agency (EMA)], there was a 
significant 61% relative risk reduction with tolvaptan (number needed to treat to prevent 
one event was ∼11). One of the inclusion criteria for the pivotal TEMPO 3:4 trial was a 
creatinine clearance as estimated with the Cockroft-Gault equation ≥60 mL/min/1.73 m2. 
Due to tubular creatinine secretion, creatinine clearance overestimates GFR by ∼20%. 
Consequently, the TEMPO 3:4 trial included a considerable number of ADPKD patients (n 
= 247; 17%) with an eGFR, as determined by the Chronic Kidney Disease Epidemiology 
Collaboration (CKD-EPI) equation, of <60 mL/min/1.73 m2. A post hoc analysis indicated 
that in these patients, treatment efficacy was similar or even slightly better than in those 
with higher eGFR. However, the number of patients with CKD stage 3b, i.e. an eGFR of 
30–45 mL/min/1.73 m2, was small. 
8.1.2 Secondary Endpoints 
The key secondary endpoint is the percent change from baseline in htTKV as measured 
by CT-scan at 24 months. The use of htTKV as a surrogate biomarker for progression of 
ADPKD is supported by the Consortium for Radiologic Imaging Study of Polycystic Kidney 
Disease (CRISP) which showed that baseline TKV strongly predicts subsequent loss of 
GFR. TKV is now widely used in RCTs for ADPKD. 
Other secondary efficacy end-points include: 
- 
Difference in rate of albuminuria change; 

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- 
Difference in rate of urological events and of hypertension onset (for not 
hypertensive patients at baseline); 
- 
Hypertension worsening or amelioration (for those who are hypertensive);  
- 
Exploratory efficacy Outcomes (changes from baseline in urinary EGF and 
EGF/MCP-1 levels). 
 
8.2 Safety Endpoints 
They include:  
- 
changes from baseline in creatinine;  
- 
vital signs;  
- 
laboratory values including liver function tests, rate of aquaretic AEs, thus including 
serum sodium, rate of Metformin Associated Lactic Acidosis, blood insulin and 
glucose levels, HOMA test in both treatment groups.  
 
9. VISITS 
9.1 Trial Procedures 
9.1.1 Screening:  
After written informed consent has been signed, assessments during the screening visits 
will include:  
1) Confirm diagnosis and determine whether the subject meets inclusion and exclusion 
criteria and record demographic information; 
2) Perform physical examination, including post-void body weight and height (first visit);  
3) Record medical/PKD history (all visits); 

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4) Record concomitant medications and ensure subject's treatment meets current standard 
of care including lifestyle and dietary recommendations, especially for ingestion of at least 
2-3 liters of fluid per day as appropriate, unless otherwise directed by study doctor (all 
visits); 
5) Assess AEs, if reported (all visits); 
6) Assess vital signs (include heart rate and blood pressure) (all visits); 
7) Serum pregnancy test for WOCBP (1st visit); 
8) Collect urine and blood samples for clinical laboratory analyses, including serum 
creatinine, liver function tests, glucose metabolism parameter, CBC and venous gas 
analysis (1st, 2nd visit); 
9) Non contrast enhanced CT-scan of the kidneys for TKV measurement (3rd visit, once 
eligibility has been confirmed). In case a patient has undergone kidney CT- or MRI-scan in 
order to measure TKV within 6 months before randomization, basal CT scan for TKV 
measurement may be not undertaken). 
9.1.2 Randomization 
Assessments during the randomization visit will include: 
1) Verification of diagnosis, inclusion and exclusion criteria and record demographic 
information; 
2) Record medical/PKD history; 
3) Record concomitant medications and ensure subject's treatment meets current standard 
of care including lifestyle and dietary recommendations, especially for ingestion of at least 
2-3 liters of fluid per day as appropriate, unless otherwise directed by study doctor; 
4) Assess AEs, if reported; 

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5) Assess vital signs (include heart rate and blood pressure); 
6) IMP dispensation; 
9.1.3 Titration period 
Assessments during up-titration phone call will include: 
1) Assess IMP tolerability; 
2) Assess AEs, if reported. 
9.1.3 Run-in Period 
Assessment at the end of run-in period visit will include: 
1) Perform physical examination, including post-void body weight and height; 
2) Record medical/PKD history; 
3) Record concomitant medications and ensure subject's treatment meets current standard 
of care including lifestyle and dietary recommendations, especially for ingestion of at least 
2-3 liters of fluid per day as appropriate, unless otherwise directed by study doctor; 
4) Assess AEs, if reported. 
5) Assess vital signs (include heart rate and blood pressure); 
6) Serum pregnancy test for WOCBP; 
7) Collect urine and blood samples for clinical laboratory analyses, including serum 
creatinine, liver function tests, glucose metabolism parameter, CBC and venous gas 
analysis; 
8) IMP dispensation; 
9) IMP reconciliation (Subjects must return any unused IMP). 
9.1.4 Treatment Period 

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Assessment at each on-treatment visit will include: 
1) Perform physical examination, including post-void body weight and height; 
2) Record medical/PKD history; 
3) Record concomitant medications and ensure subject's treatment meets current standard 
of care including lifestyle and dietary recommendations, especially for ingestion of at least 
2-3 liters of fluid per day as appropriate, unless otherwise directed by study doctor; 
4) Assess AEs, if reported; 
5) Assess vital signs (include heart rate and blood pressure); 
6) Serum pregnancy test for WOCBP; 
7) Collect urine and blood samples for clinical laboratory analyses, including serum 
creatinine, liver function tests, glucose metabolism parameter, CBC and venous gas 
analysis; 
8) IMP dispensation; 
9) IMP reconciliation (subjects must return any unused IMP); 
10) Non contrast enhanced CT-scan of the kidneys for TKV measurement (at the end of 
month 24). 
9.1.5 Follow-up Period 
Assessments at each follow-up visit will include: 
1) Perform physical examination, including post-void body weight and height; 
2) Record medical/PKD history; 

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3) Record concomitant medications and ensure subject's treatment meets current standard 
of care including lifestyle and dietary recommendations, especially for ingestion of at least 
2-3 liters of fluid per day as appropriate, unless otherwise directed by study doctor; 
4) Assess AEs, if reported; 
5) Assess vital signs (include heart rate and blood pressure); 
6) Serum pregnancy test for WOCBP (second visit); 
7) Collect urine and blood samples for clinical laboratory analyses, including serum 
creatinine, liver function tests, glucose metabolism parameter, CBC and venous gas 
analysis (second visit). 
The above follow-up assessments will also be performed for a subject who interrupts IMP 
for more than 10 days, in order to collect their data in the event that they never restart IMP 
treatment. 
9.1.6 Efficacy Assessments 
9.1.6.1 Serum Creatinine for Estimated Glomerular Filtration Rate 
The serum creatinine concentration is related to eGFR and is commonly used to estimate 
renal function in clinical practice. Alteration in metabolism of creatinine and methodological 
interference in its measurements may impact accuracy of the serum creatinine and renal 
function estimation.  Below are suggested measures to decrease serum creatinine 
variability prior to the monthly blood draws required by this protocol: 
- 
Maintain a stable dietary protein intake and avoid very different or high cooked meat protein 
meals the day before each scheduled serum creatinine assessment; 
- 
Maintain a stable exercise routine and avoid very different or heavy physical  
activity/exercise the day before each scheduled serum creatinine assessment; 

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- 
Maintain a stable water intake, aimed at avoiding thirst consistently throughout the trial - 
recommended ingestion of at least 2-3 liters of fluid (including in solid, semi-solid, and liquid 
foods) per day, unless otherwise directed by your study doctor; 
- 
Plan to arrive at the same time for each blood-draw and clinic visit to better standardize 
time of the sample collection throughout the trial; 
- 
Avoid forbidden medications. 
Serum creatinine is stable when stored frozen; therefore, blood sample will be analyzed by 
the laboratory as soon as it is received and accessioned. 
Ongoing, analysis will be conducted for each subject upon his/her individual completion of 
all their assessments within the trial (not at the end of the trial). 
The eGFR values will be calculated from the laboratory serum creatinine concentrations 
taken at screening and during every trial visit. In the screening period, the first two 
assessments must be used to determine the eGFR values that will be averaged for 
determination of meeting inclusion criteria.  
9.1.6.2 TKV measurement 
Abdomen-pelvis CT-scan will be performed by using a 320-row multi detector device and 
the following acquisition parameters will be used: slice thickness 0.5 mm, increment 0.5 
mm, rotation time 0.5 s; 120/200 kVp/mAs. 
An automatic dose modulation system will be used in all cases. Images will be acquired 
without intravenous injection of iodinate contrast material. Scans will be performed from 
the diaphragm to the pubic symphysis. 
CT data will be centrally transferred to and analysed on a workstation (HPXW8600), 
present within the DETO equipped with software dedicated to image reconstruction (Vitrea 
FX 2.1, Vital Images, Minneapolis, MN, USA). For each patient, Multi-planar 
Reconstructions (MPR) on the axial, coronal and sagittal planes and Volume Rendering 

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(VR) images will be used in order to assess renal parenchyma. A radiologist with more 
than 10-year experience in the field of abdominal CT will manually trace both kidneys 
(renal parenchyma and all cysts including exophytic cysts), excluding the renal pelvis and 
other hilar vascular structures. The semi-automatic 3D Analysis software will be used in 
order to quantify the TKV for each CT examination. All changes in TKV (delta TKV) will be 
calculated by analyzing any variation of absolute TKV values deriving from the different CT 
examinations. 
9.1.6.3 Polycystic Kidney Disease History and Outcomes Surveys 
A short PKD history survey will be completed once during screening to capture information 
from the subject’s recollection, and documented past medical history where available. The 
survey should be updated at each visit if new information regarding past history becomes 
available. 
The PKD outcomes survey will collect information relevant to the medical, social and 
economic consequences of new and ongoing PKD-related morbidities. New clinically 
relevant information and specific questions about outcomes will be collected at the 
following visits: screening, end of run-in, and during the unblind randomized treatment 
period either monthly (over the phone or in person). 
If a subject who has been randomized discontinues the use of IMP, PKD outcomes will be 
collected at the normally scheduled trial visits, or by telephone contact, to the date of the 
originally planned Month 12 visit, if the subject agrees. 
9.1.6.4 Urinary Epidermal Growth Factor and Monocyte Chemotactic Peptide-1 
A number of studies tried to identify molecular markers of rapid disease progression in 
ADPKD, but nowadays eGFR and TKV are the most important. 

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Epidermal Growth Factor (EGF) is a renal tubular-specific protein that exerts a key role in 
cellular differentiation and regeneration after kidney damage. For this reason, urinary EGF 
(uEGF) is considered a surrogate marker of renal tubular cells to regenerate after acute or 
chronic damage. 
An Italian study showed lower uEGF levels in those ADPKD patients affected by renal 
insufficiency, than in those with normal renal function (77). Prognostic value of uEGF has 
been subsequently confirmed in another study conducted in CKD (78), that showed as 
uEGF is an independent risk factor for CKD progression characterized by higher sensitivity 
than serum creatinine. 
Urinary Monocyte Chemotactic Peptide-1 (uMCP-1), in ADPKD seems to increase before 
than serum creatinine or than proteinuria and intracystic levels of uMCP-1 are higher than 
those found in urine or serum (79). 
Moreover, as uEGF/uMCP-1 ratio was found to be a sensible prognostic marker of ESRD 
in IgA Nephropathy, likewise it could be a useful biomarker in ADPKD (80). 
 
9.2 Definition of Source Data 
The Investigator shall permit the authorized Investigator-Promoter, his representatives, 
and regulatory agencies to enter and inspect any site where the drug or records pertaining 
to the drug are held, and to inspect all records relating to an investigation, including 
subject records. Completed eCRFs must be available by the Investigator for review by the 
Investigator-Sponsor, his representatives, the monitor and the regulatory agencies. To 
ensure the accuracy of data submitted, it is mandatory that representatives of the 
Investigator-Promoter and of the regulatory agencies have direct access to source 
documents. 

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Source documents are defined as the results of original observations and activities of a 
clinical investigation.  Source documents will include but are not limited to progress notes, 
electronic data, screening logs, and recorded data from automated instruments.  All source 
documents pertaining to this trial will be maintained by the investigators. 
Investigator(s)/institution(s) will permit trial-related monitoring, audits, IRB/IEC review, and 
regulatory inspection(s) by providing direct access to source data/documents by 
authorized persons as defined in the ICF. 
9.2.1 Data Collection 
During each subject’s visit to the clinic, a clinician participating in the trial will record 
progress notes to document all significant observations. At a minimum, these notes will 
contain: 
o Documentation of the informed consent process, including any revised consents; 
o The date of the visit and the corresponding Visit or Day in the trial schedule; 
o General subject status remarks, including any significant medical findings; 
o The severity, frequency, duration, action taken, and outcome of any AEs and the 
investigator's assessment of relationship to IMP must also be recorded; 
o Any changes in concomitant medications or dosages; 
o A general reference to the procedures completed; 
o The signature (or initials) and date of each clinician (or designee) who made an 
entry in the progress notes. 
In addition, any contact with the subject via telephone or other means that provides 
significant clinical information will also be documented in the progress notes as described 
above.  

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Any changes to information in the trial progress notes and other source documents will be 
initialed and dated on the day the change is made by a site staff member authorized to 
make the change. Changes will be made by striking a single line through erroneous data 
(so as not to obliterate the original data), and clearly entering the correct data (e.g., wrong 
data right data). 
Information from the trial progress notes and other source documents will be entered by 
investigative site personnel directly onto eCRFs in the sponsor’s electronic data capture 
system. Changes to the data will be captured by an automatic audit trail. 
9.2.2 File Management at the Trial Site 
The investigator will ensure that the trial site file is maintained in accordance with Section 
8 of the ICH GCP Guideline and as required by applicable local regulations. The 
investigator/institution will take measures to prevent accidental or premature destruction of 
these documents. 
9.2.3 Records Retention at the Trial Site 
Regulatory requirements for the archival of records for this trial necessitate that 
participating investigators maintain detailed clinical data for the longest of the following 3 
periods: 
o A period of at least 2 years following the date on which approval to market the drug 
is obtained (or if IMP development is discontinued, the date regulatory authorities 
were notified of discontinuation); OR 
o A period of at least 3 years after the sponsor notifies the investigator that the final 
report has been filed with regulatory authorities. 
The investigator must not dispose of any records relevant to this trial without written 
permission from the Promoter. 

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The investigator will be responsible to maintain adequate and accurate electronic or hard 
copy source documents of all observations and data generated during this trial.  Such 
documentation is subject to inspection by the Promoter and relevant regulatory authorities.  
If the investigator withdraws from the trial (e.g., due to relocation or retirement), all trial-
related records should be transferred to a mutually agreed-upon designee within a 
sponsor-specified timeframe. Notice of such transfer will be given to the Promoter in 
writing. 
 
10. SAFETY MONITORING AND REPORTING 
10.1 Adverse Event 
This section describes the methods and timing for assessing, recording, and analyzing 
safety parameters, as well as the procedures for eliciting reports of and recording and 
reporting AEs and intercurrent illnesses and the type and duration of the follow-up of 
subjects after AEs. 
ADPKD is a progressive disorder involving the kidney, liver and occasionally other organ 
systems. A number of AEs may be associated with this disorder and are endpoints in this 
trial, including urine concentration defects, hypertension, renal pain, renal infection, 
nephrolithiasis, hematuria, and ESRD. As such, these events are considered “expected” in 
this trial population and will not qualify for the purposes of regulatory expedited reporting. 
These events will be evaluated on a regular basis by the trial’s Medical Monitor and the 
sponsor’s Safety group. 
 
10.1 Adverse Event Definitions and Classifications 

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Subjects must be carefully monitored for adverse events. Adverse events should be 
assessed in terms of their seriousness, severity, and relationship to the study drug. 
The intensity or severity of adverse events should be graded according to NCI CTCAE (v 
5.0) criteria. 
10.1.1 Adverse Event  
An adverse event is any untoward medical occurrence in a clinical study subject 
administered a pharmaceutical product. An adverse event does not necessarily have a 
causal relationship with the treatment. An adverse event can therefore be any 
unfavourable and unintended sign (including an abnormal finding), symptom, or disease 
temporally associated with the use of a medicinal (investigational) product, whether or not 
related to the medicinal (investigational) product. (Definition per International Conference 
on Harmonization [ICH]). 
This includes any occurrence that is new in onset or aggravated in severity or frequency 
from the baseline condition, or abnormal results of diagnostic procedures, including 
laboratory test abnormalities. 
10.1.3 Serious Adverse Event 
A Serious Adverse Event (SAE) is any untoward medical occurrence that at any dose:  
- 
results in death; 
- 
is life-threatening (defined as an event in which the subject was at risk of death at 
the time of the event; it does not refer to an event which hypothetically might have 
caused death if it were more severe); 
- 
requires inpatient hospitalization or causes prolongation of existing hospitalization; 
- 
results in persistent or significant disability/incapacity; 
- 
is a congenital anomaly/birth defect;  

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- 
is an important medical event (defined as a medical event(s) that may not be 
immediately life-threatening or result in death or hospitalization but, based upon 
appropriate medical and scientific judgment, may jeopardize the subject or may 
require intervention [e.g., medical, surgical] to prevent one of the other serious 
outcomes listed in the definition above.) Examples of such events include, but are 
not limited to, intensive treatment in an emergency room or at home for allergic 
bronchospasm; blood dyscrasias or convulsions that do 
not result in 
hospitalization); 
- 
Transaminase levels raise above 5xUNL; 
- 
Transaminase and total bilirubin 2xUNL; 
- 
Clinical signs of Drug Induced Liver Injury (e.g., jaundice, right upper quadrant 
pain); 
- 
Lactic Acidosis (as defined by pH<7,3 and Lactate> 4 mmol/l); 
- 
Death; 
- 
Pregnancy; 
- 
Malignancies; 
- 
Onset of permanent medical conditions contraindicating metformin or tolvaptan 
treatment (i.e.: myocardial infarction, severe chronic arrhythmias, chronic 
respiratory failure). 
 
10.1.4 Serious Adverse Event Collection and Reporting 
Following the subject’s written consent to participate in the study, all SAEs, whether 
related or not related to study drug, must be collected, including those thought to be 
associated with protocol-specified procedures.  
If only limited information is initially available, follow-up reports are required.  

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If an ongoing SAE changes in its intensity or relationship to study drug or if new 
information becomes available, a follow-up SAE report should be sent within 24 hours to 
the Sponsor (or designee) using the same procedure used for transmitting the initial SAE 
report. All SAEs should be followed to resolution or stabilization. 
10.1.5 Unlisted (Unexpected) Adverse Event 
An unlisted adverse event is an event the nature or severity of which is not consistent with 
the applicable product information. The expectedness of an adverse event will be 
determined by whether or not it is listed in the summary of product characteristics (SmPC). 
10.1.6 Adverse Event Associated With the Use of the Drug 
An adverse event is considered associated with the use of the drug if the attribution is 
possible, probable, or very likely by the definitions listed in Section 10.1.7. 
10.1.7 Intensity (Severity) Reporting and Attribution 
For both serious and non-serious adverse events, the Investigator must determine both 
the intensity of the event and the relationship of the event to study drug administration. 
Intensity for each adverse event will be determined by using Version 4.0 of the National 
Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) as a 
guideline, wherever possible; a copy of the NCI-CTCAE Version 4.0 can be downloaded 
from 
the 
Cancer 
Therapy 
Evaluation 
Program 
(CTEP) 
home 
page 
(http://evs.nci.nih.gov/ftp1/CTCAE/About.html). In those cases where the NCI CTCAE 
does not apply, intensity should be defined according to the following criteria: 
- 
Mild: Awareness of sign or symptom, but easily tolerated; 
- 
Moderate: Discomfort enough to cause interference with normal daily activities; 
- 
Severe: Inability to perform normal daily activities; 
- 
Life Threatening Immediate risk of death from the reaction as it occurred. 

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Relationship to study drug administration will be determined as follows: 
- 
Not related: An adverse event which is not related to the use of the drug; 
- 
Unlikely/Doubtful:An adverse event for which an alternative explanation is more 
likely, e.g., concomitant drug(s), concomitant disease(s), or the relationship in time 
suggests that a causal relationship is unlikely; 
- 
Possible: An adverse event which might be due to the use of the drug. An 
alternative explanation, e.g., concomitant drug(s), concomitant disease(s), is 
inconclusive. The relationship in time is reasonable; therefore, the causal 
relationship cannot be excluded; 
- 
Probable: An adverse event which might be due to the use of the drug. The 
relationship in time is suggestive (e.g., confirmed by dechallenge). An alternative 
explanation is less likely, e.g., concomitant drug(s), concomitant disease(s); 
- 
Definite/Very Likely: An adverse event which is listed as a possible adverse 
reaction and cannot be reasonably explained by an alternative explanation, e.g., 
concomitant drug(s), concomitant disease(s). The relationship in time is very 
suggestive (e.g., it is confirmed by dechallenge and rechallenge). 
10.1.8 Relationship of Adverse Event to Investigational Product  
The assessment of the relationship of an adverse event to the administration of study drug 
is a clinical decision based on all available information at the time of the completion of the 
CRF. 
An assessment of ‘No’ would include: 
1. The existence of a clear alternative explanation (e.g., mechanical bleeding at 
surgical site) OR 

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2. Non-Plausibility (e.g., the subject is struck by an automobile when there is no 
indication that the drug caused disorientation that may have caused the event; 
cancer developing a few days after the first drug administration). 
An assessment of ‘Yes’ indicates that there is a reasonable suspicion that the adverse 
event is associated with the use of the investigational drug. Factors to be considered in 
assessing the relationship of the adverse event to study drug include: 
1. The temporal sequence from drug administration: the event should occur after the 
drug is given. The length of time from drug exposure to event should be evaluated 
in the clinical context of the event. 
2. Recovery 
on 
discontinuation 
(de-challenge), 
recurrence 
on 
reintroduction 
(rechallenge): 
Subject’s response after drug discontinuation (de-challenge) or subjects response after 
drug re-introduction (re-challenge) should be considered in the view of the usual clinical 
course of the event in question. 
- 
Underlying, concomitant, intercurrent diseases: each report should be evaluated in 
the context of the natural history and course of the disease being treated and any 
other disease the subject may have; 
- 
Concomitant medication or treatment: The other drugs the subject is taking or the 
treatment the subject receives should be examined to determine whether any of 
them may be suspected to cause the event in question; 
- 
The pharmacology and pharmacokinetics (PK) of the test drug: The PK properties 
(absorption, distribution, metabolism and excretion) of the test drug(s), coupled with 
the individual subject’s pharmacodynamics should be considered. 
10.1.9 Reporting of Adverse Events 

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All adverse events that occur between the first study-related procedure and 100 days after 
the last dose of study drug will be reported. All events that meet the definition of a serious 
adverse event will be reported as serious adverse event, regardless of whether they are 
protocol-specific assessments. 
All adverse events, regardless of seriousness, severity, or presumed relationship to study 
therapy, must be recorded using medical terminology in the source document and the 
CRF. Whenever possible, diagnoses should be given when signs and symptoms are due 
to a common etiology (e.g., cough, runny nose, sneezing, sore throat, and head 
congestion should be reported as “upper respiratory infection”). Investigators must record 
in the CRF their opinion concerning the relationship of the adverse event to study therapy. 
All measures required for adverse event management must be recorded in the source 
document and reported according to sponsor instructions. 
All grade 3 and 4 adverse events, considered related, must be followed until resolution of 
the event, or the event improves to a grade 2 or better.  
10.1.10 Reporting of Serious Adverse Events/Pregnancy 
Serious adverse events, including laboratory test abnormalities fulfilling the definition of 
serious, occurring during the study and follow-up period must immediately (within 24 hours 
of the investigator’s awareness) be reported to the Investigator-Sponsor or his delegate. 
Name and address for this purpose will be supplied on a Contact Information Form. 
Information regarding serious adverse events will be transmitted to the Investigator-
Sponsor or his delegate using the Serious Adverse Event Form, which must be signed by 
a member of the investigational staff. The initial report of a serious adverse event may be 
reported by fax or by email. It is preferable that serious adverse events be reported via fax. 
Subsequent to a report of a serious adverse event, a Serious Adverse Event Form must 

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be completed by the investigational staff and transmitted to the Investigator-Sponsor within 
1 working day. 
The cause of death of a subject in a clinical study, whether or not the event is expected or 
associated with the investigational agent, is considered a serious adverse event. Any 
event requiring hospitalization (or prolongation of hospitalization) that occurs during the 
course of a subject’s participation in a clinical study must be reported as a serious adverse 
event, except hospitalizations for: 
- 
social reasons in absence of an adverse event; 
- 
surgery or procedure planned before entry into the study (must be documented in 
the CRF); 
- 
study drug administration; 
- 
study related procedures defined in the protocol. 
The Investigator-Sponsor should report serious unexpected adverse events to the 
appropriate Independent Ethics Committee (IEC) that approved the protocol unless 
otherwise required and documented by the IEC. The Investigator-Sponsor assumes 
responsibility for appropriate reporting of serious unexpected adverse events to Regulatory 
Authorities. 
Each serious adverse event must be followed up until resolution or stabilization by 
submission of updated reports to the designated person. An isolated laboratory 
abnormality that is assigned grade 4, according to CTC definition, is not reportable as a 
serious adverse event, unless the investigator assesses that the event meets standard 
International Conference on Harmonization (ICH) criteria for a serious adverse event (see 
definition Section 10.1.3).  
CTC grade 4 baseline laboratory abnormalities that are part of the disease profile should 
not be reported as a serious adverse event, specifically when they are allowed or not 

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excluded by the protocol inclusion/exclusion criteria. If an investigator is in doubt about the 
applicable reporting obligations, he/she should consult with the chairman or the 
Investigator-Sponsor. 
CTC grade 4 laboratory abnormalities will be recorded in the dedicated section of the 
electronic CRF and will be reviewed on a regular basis. 
10.1.11 Pregnancy 
Women of childbearing potential who are sexually active must use an effective method of 
birth control during the course of the trial and for 30 days after the last dose of IMP in a 
manner such that risk of failure is minimized. Unless the subject is sterile (i.e., women who 
have had a bilateral oophorectomy and/or hysterectomy or have been postmenopausal for 
at least 12 consecutive months) or remains abstinent, 2 of the following precautions must 
be used: vasectomy, tubal ligation, intrauterine device, birth control pills, birth control depot 
injection, birth control implant, condom or occlusive cap (diaphragm or cervical/vault caps) 
with spermicide.  Any single method of birth control, including vasectomy and tubal 
ligation, may fail, leading to pregnancy. 
Before enrolling WOCBP in this clinical trial, investigators must review guidelines about 
trial participation for WOCBP.  The topics should generally include: 
 General information; 
 ICF; 
 Pregnancy prevention information; 
 Drug interactions with hormonal contraceptives; 
 Contraceptives in current use; 
 Guidelines for the follow-up of a reported pregnancy. 

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Prior to trial enrollment, WOCBP must be advised of the importance of avoiding pregnancy 
during trial participation and the potential risk factors for an unintentional pregnancy. The 
subject must sign an informed consent form stating that the above- mentioned risk factors 
and the consequences were discussed with her. 
During the trial, all WOCBP should be instructed to contact the investigator immediately if 
they suspect they might be pregnant (e.g., missed or late menstrual cycle). 
If a subject or investigator suspects that the subject may be pregnant prior to 
administration of the investigational product, administration must be withheld until the 
results of blood serum pregnancy tests are available.  If the pregnancy is confirmed, the 
subject must not receive IMP or be enrolled in the trial.  If pregnancy is suspected while 
the subject is receiving treatment, IMP must be withheld immediately (if reasonable, taking 
into consideration any potential withdrawal risks) until the result of a serum pregnancy test 
is known.  If pregnancy is confirmed, IMP will be interrupted or withheld in an appropriate 
manner (e.g., dose tapering if necessary for subject safety) and the subject will continue to 
be monitored for the duration of the remainder of the trial or of their pregnancy. Subjects 
who permanently discontinue IMP due to pregnancy may continue to be monitored in the 
same manner as other subjects to their 24-month visit. 
The investigator must immediately notify the Promoter of any pregnancy associated with 
IMP exposure during the trial and for 30 days after the last dose of IMP and record the 
event on the IRE form and forward it to the sponsor.  The sponsor will forward Pregnancy 
Surveillance Form(s) for monitoring the outcome of the pregnancy. 
Protocol required procedures for IMP discontinuation and follow-up must be performed on 
the subject unless contraindicated by pregnancy (e.g., x-ray studies). Other appropriate 
pregnancy follow-up procedures should be considered if indicated.  In addition, the 
investigator must report to the sponsor, on appropriate Pregnancy Surveillance form(s), 

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follow-up information regarding the course of the pregnancy, including perinatal and 
neonatal outcome.  Infants will be followed for a minimum of 6 months. 
 
10.2 Follow-up of Adverse Events 
For this trial, AEs will be followed up for 7 days in subjects who discontinued prior to 
randomization and for 21 days after the last dose of IMP has been administered (follow- up 
period) in subjects who were randomized. 
Subjects experiencing SAEs should be followed clinically until their health has returned to 
baseline status, or until all parameters have returned to normal, or have otherwise been 
explained. 
For subjects who have discontinued IMP but have not withdrawn from the trial, vital status, 
AEs, concomitant medications, ESRD status, and scheduled laboratory data (including 
serum creatinine data) are planned to be collected regardless of IMP discontinuation until 
the scheduled end of the trial. 
10.2.1 Follow-up of Non-serious Adverse Events 
Non-serious AEs that are identified on the last scheduled contact must be recorded on the 
AE eCRF with the current status noted.  All non-serious events that are ongoing at this 
time will be recorded as ongoing on the eCRF. 
10.2.2 Follow-up of Post-Trial Serious Adverse Events 
Serious AEs that are identified on the last scheduled contact must be recorded on the AE 
eCRF page and reported to the Promoter This may include unresolved previously reported 
SAEs, or new SAEs.  

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The investigator will follow SAEs until the events are resolved, or the subject is lost to 
follow-up.  Resolution means the subject has returned to the baseline state of health, or 
the investigator does not expect any further improvement or worsening of the subject’s 
condition.  The investigator will continue to report any significant follow-up information to 
OPDC up to the point the event has been resolved. 
10.2.3 Follow-up and Reporting of Serious Adverse Events Occurring after Last 
Scheduled Contact 
Any new SAEs reported by the subject to the investigator that occur after the last 
scheduled contact, and are determined by the investigator to be reasonably associated 
with the use of the IMP, should be reported to OPDC.  This may include SAEs that are 
captured on follow-up telephone contact or at any other time point after the defined trial 
period (i.e., up to last scheduled contact). The investigator should follow potentially IMP-
related SAEs identified after the last scheduled contact until the events are resolved, or the 
subject is lost to follow-up. The investigator should continue to report any significant follow-
up information to OPDC up to the point the event has been resolved. 
 
10.3 Clinical Laboratory Assessments 
Blood and/or urine samples will be collected as indicated in the schedule of assessments 
(Fig.1). It is preferable to collect the clinical laboratory samples from each subject at a 
consistent time of day throughout the trial, and to recommend that the subject have a 
similar diet, avoiding variation in protein intake (especially cooked meat protein), and 
exercise pattern during these periods, in order to reduce variability in the samples over 
time. 

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Liver panels will be analyzed monthly during the unblind, treatment period using both 
central and local labs, as needed, and per standard of care according to the subject’s 
individual medical needs.  
Serum pregnancy testing and Blood venous gas-analysis will be performed locally during 
screening period and then during every scheduled visit. 
 
10.4 Physical Examination and Vital Signs 
A full physical examination will be performed and documented during every visit and 
during End of Treatment visit. Any changes in medication or AEs will be recorded in the 
eCRF. Body weight will be taken post-void. It is preferable to use the same scale for each 
measurement. 
The investigator or his/her appointed designee is primarily responsible to perform the 
physical examination. If the appointed designee is to perform the physical examination, 
he/she must be permitted to do so by local regulations and his/her name must be included 
on any globally and locally required documents. 
Whenever possible, the same individual should perform all physical examinations.  Any 
undesirable condition present at a post-treatment physical examination that was not 
present at the baseline examination should be documented as an AE and followed to a 
satisfactory conclusion. 
Vital sign data, including seated blood pressure, heart rate, temperature, height, and 
weight, will be taken at the visits identified in the Schedule of Assessments. 
 
10.5 Assessment of Liver Symptoms, Signs or Test Abnormalities 

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Testing for hepatic transaminase (ALT/AST), alkaline phosphatase, and BT will be 
performed during screening visits. Testing for hepatic transaminase (ALT/AST) will be 
performed during run-in and at each monthly visit in the tolvaptan arm, whereas it will be 
performed during three monthly visits in the metformin arm. 
10.5.1 Requirements for Repeated Liver Testing 
10.5.1.1 Repeated Liver Testing in Subjects with Normal Values at Screening 
The appearance of any suspicious symptom or sign should trigger prompt testing of 
hepatic function (i.e., within 72 hours). Local laboratory testing is acceptable, ideally with a 
concurrent central laboratory sample for confirmation. 
Any transaminase or bilirubin values which exceed 2 x ULN should also prompt immediate 
retesting within 72 hours. While values remain in an abnormal range, testing frequency 
should be increased to at least weekly for the first month, gradually returning to 
monthly/three monthly as indicated by the results. 
Subjects exhibiting such an increase during the tolvaptan titration/run-in phases will be 
disqualified from randomization on safety grounds and should not be randomized. 
Should the cause of the abnormality be determined to be unrelated to tolvaptan exposure 
(e.g., having identified a plausible alternative explanation) such a subject may be re-
screened only with medical monitor approval. 
10.5.1.2 Repeated Liver Testing in Subjects with Abnormal Values at Screening 
Subjects found to have liver laboratory abnormalities at screening or who have a history of 
non-ADPKD-related liver disease will require further evaluation. These subjects will need 
to have the special liver eCRF completed and additional testing will be required during 
screening (to confirm the stability of the abnormality) and during the tolvaptan run-in phase 
at least 1 week prior to randomization (to confirm eligibility for randomization). 

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Management of such subjects should be closely coordinated with the trial’s Medical 
Monitor.  In these subjects, further changes in liver test levels of > 2 x upper limit of their 
highest screening value at any point post-screening should prompt re-testing within 72 
hours. Should such increase occur in the tolvaptan titration/run-in phase, the subject will 
be disqualified from trial. 
10.5.1.3 Liver Test Abnormalities and Interruption/Discontinuation of Investigational 
Medicinal Product 
Liver transaminase or bilirubin levels reaching or exceeding 2 x ULN that have an 
uncertain or rapidly increasing trajectory should prompt at least temporary IMP 
interruption. IMP should not be resumed until monitoring indicates abnormalities have 
resolved, are stable or are not rapidly increasing, and then only with an increased 
frequency of monitoring. 
Subjects would not typically be allowed to resume treatment with IMP if they have: 
- 
transaminase levels rise above 8 x ULN; 
- 
transaminase levels are > 5 x ULN for more than 2 weeks; or 
- 
concurrent elevations of transaminase > 3 x ULN and BT > 2 x ULN. 
Subjects with these levels of abnormality may be re-challenged with IMP if abnormalities 
were adjudicated as having a < 50% likelihood of being related to IMP (per DILI network 
[DILIN] probability criteria) by the investigator and medical monitor. 
All elevations will be assessed by the medical monitoring team. The subject must also be 
willing to comply with these monitoring measures, be informed of the potential risks, and 
consent to IMP re-challenge. 
 
10.6 Assessment of Metformin Associated Lactic Acidosis (MALA) 

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In order to assess acid-base status in treated patients and in order to limit the patient 
discomfort, peripheral venous blood gas analysis (pVBGA) will be performed during 
scheduled and unscheduled visits. 
The appearance of any suspicious symptom or sign should trigger prompt testing (pVBGA) 
(i.e., within 24 hours). Local laboratory testing is always permitted. 
The investigator must follow the following rules: 
 
lactate level is between 2-4 mmol/l and pH over 7.35, pVBGA has to be promptly repeated 
within 24 hours. If confirmed, patient has to reduce metformin dosage (from 1500 mg a day 
to 1000 mg a day or from 1000 mg a day to 500 mg a day). pVBGA has to be repeated 
every other day for 1 week till normalization. Once restored normal values, patient can up-
titrate to the former dosage and pVBGA has to be retested after 7 days. If normal, patient 
can keep on treatment, otherwise meformin dosage has to be reduced as previously 
described till normalization. In this case higher dosage can not be restored. 
In both cases, if pVBGA fail to restore, metformin has to be permanently stopped. In this 
case, EoTx visit has to be collected and the patient has to be followed up for 21 days. 
 
lactate level is higher than 4 mmol/l with sVO2 between 30-50% (irrespective of pH) or 
lactate between 2-4 mmol/l but associated to pH lower than 7.35. In these cases IMP must 
be suspended and patient hospitalized. If AEs fails to recover in 3 weeks, IMP must be 
permanently discontinued. 
Once AEs recovered the patient can undergo IMP re-challenge, by restarting since 
metformin titration. In this case pVBGA has to be performed every week prior to up-titration. 
If pVBGA is normal, the patient can uptitrate, otherwise meformin dosage has to be 
reduced till the minimum allowed dosage (that is 1000 mg a day) as previously described till 
normalization. 
If pVBGA fail to restore, metformin has to be permanently stopped. In this case, EoTx visit 
has to be collected and the patient has to be followed up for 21 days. 
 

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10.7 Assesment of Metformin Associated Megaloblastic Anemia (MAMA) 
The pathogenic mechanisms of vitamin B12 deficiency in metformin treatment have not 
been fully elucidated. However, among the instances of bacterial overgrowth in the small 
intestine attributable to diabetes mellitus, changes in small bowel motility, alterations in the 
bacterial flora, competitive inhibition, the inactivation of vitamin B12 absorption, or the effect 
of calcium on cell membranes have been suggested to play a role. 
Vitamin B12 deficiency is clinically important because it is a reversible cause of bone 
marrow failure and demyelinating nerve disease. Neurologic damage, a possible 
consequence of metformin-induced vitamin B12 deficiency, can present as peripheral 
neuropathy and may be mistaken for diabetic neuropathy in patients on metformin 
treatment. 
Some studies (81–83) showed a clear relationship between the dosage or duration of 
metformin use and vitamin B12 deficiency in patients with type 2 diabetes, with an 
incidence of 19% after 4 years of treatment. Subjects with metformin use ≥10 years and 
daily dosage ≥2,000 mg show about a 4-fold higher risk of vitamin B12 deficiency 
compared to those with metformin use of <4 years and daily dosage of ≤1,000 mg. The 
presence of anemia shows a statistically positive association with vitamin B12 deficiency.  
For these reasons Cianocobalamin blood dosage and Complete Blood Count will be 
regularly performed. In case of Cianocobalamin deficiency onset, oral supplementation will 
be allowed. 
 
11. TREATMENT/STUDY DISCONTINUATION  
Patients should be informed of circumstances under which their participation may be 
terminated by the Investigator without their consent. 

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A subject may temporarily or permanently discontinue IMP for a number of reasons listed 
below: 
1. Reasons related to AE: 
a. Subject could not tolerate IMP due to an AE which is annoying or 
uncomfortable but not serious or hazardous, 
b. Physician determined that there are potential IMP related safety concern or 
SAE placing subject at undue hazard, 
c. Serious adverse event (SAE), 
d. Progression of disease leading to dialysis, transplantation or eGFR decline 
as determined by the investigator, 
e. Blood Venous Gas abnormalities meeting criteria for MALA, 
f. Clinical signs of MALA, 
g. Fever or diarrhea, 
h. Liver test abnormalities meeting criteria for permanent discontinuation, 
i. Clinical signs of DILI (e.g., jaundice, right upper quadrant pain). 
2. Death; 
3. Reasons unrelated to medical condition (e.g., pregnancy, trial too burdensome); 
4. Withdrawal of informed consent (partial related to IMP or complete from the trial); 
5. Lost to follow-up (detailed procedures to prevent subjects from becoming “lost to 
follow-up will be provided in the operations manual. These procedures must be 
followed by the investigator, their staff or other designated trial personnel); 
6. Termination of all or part of the trial by the Promoter; 
7. Fall of eGFR below 15 ml/min (in case of tolvaptan treatment), below 30 ml/min (in 
case of metformin treatment); 

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8. Peripheral BVG predicting lactic acidosis onset (sVO2 between 30-50% and Lactate 
levels greater than 3,5 mmol/l; in this case ABG must be performed). In these cases 
IMP must be suspended for maximum 3 weeks and resumed once AEs recovered. 
If AEs fails to recover in 3 weeks, IMP must be permanently discontinued. 
Any administrative or other reasons for withdrawal must be documented and explained to 
the patient. 
If the reason for removal of a patient from the study is an AE, the principal specific event 
will be recorded on the eCRF. The patient should be followed until the AE has resolved, if 
possible. All patients will be followed for 21 days following the last dose of study 
medication- 
If the subject temporarily interrupts or discontinues IMP due to an AE, the investigator, or 
other trial personnel, will make every effort to follow the event until it has resolved or 
stabilized. 
If lost to follow-up, the Investigator should make every effort to contact the patient by 
telephone or by sending a registered letter to establish as completely as possible the 
reason for the withdrawal. A complete final evaluation at the time of the patient’s 
withdrawal should be made with an explanation of why the patient is withdrawing from the 
study. 
If the Promoter terminates or suspends the trial for safety or unanticipated other reasons, 
prompt notification will be given to investigators, IRBs/IECs, and regulatory authorities in 
accordance with regulatory requirements. 
The Investigator will notify the Promoter promptly if the trial is terminated by the 
investigator or the IRB/IEC at the site. If the investigator, IRB/IEC or sponsor decides to 
terminate or suspend the trial’s conduct at a particular center for safety, non-enrollment of 

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subjects, non-compliance with the protocol, or unanticipated other reasons, the above and 
other parties, as required by the applicable regulatory requirements, will be promptly 
notified. 
If a subject discontinues during the screening period (because of consent withdrawal or 
failure to meet all of the requirements to continue in the trial) that subject will be 
considered a “Screen failure”. Subjects who fail to meet trial requirements during the 
screening period may be rescreened at a later date. 
Screen failure subjects will be recorded as such on the eCRF. Screening failure subjects 
do not require follow-up and can be considered for rescreening if the reason for the screen 
failure was not that the subject withdrew their consent.  If rescreened, the subject will sign 
a new informed consent, will be assigned a new screening number, and will repeat all 
screening procedures. 
If a subject discontinues during the IMP titration period or during the IMP Run-in period, 
that subject will be considered a “Titration failure” or a “Run-in failure”. 
Discontinuation during these two periods may be due to any of the following reasons: 
- 
Subject does not meet entry requirements (i.e., subject cannot tolerate IMP 
treatment) as specified for a particular pre-randomization period; 
- 
Subject decides to formally withdraw consent and/or fails to return for subsequent 
appointments at the trial site; 
- 
Investigator considers the subject unsuitable for further participation. 
“Titration failure” or a “Run-in failure” subjects will be recorded as such on the eCRF, they 
will complete an EoTx visit upon withdrawal from the trial. 
The EoTx visit assessments will include: 
1) Perform physical examination, including post-void body weight and height; 

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2) Record medical/PKD history; 
3) Record concomitant medications and ensure subject's treatment meets current standard 
of care including lifestyle and dietary recommendations, especially for ingestion of at least 
2-3 liters of fluid per day as appropriate, unless otherwise directed by study doctor; 
4) Assess AEs, if reported; 
5) Assess vital signs (include heart rate and blood pressure); 
6) Serum pregnancy test for WOCBP (second visit); 
7) Collect urine and blood samples for clinical laboratory analyses, including serum 
creatinine, liver function tests, glucose metabolism parameter, CBC and venous gas 
analysis (second visit). 
Run-in failure subjects will then be followed up after 7 days with a phone call to record any 
ongoing AEs; unless the subject fully withdraws consent to any further follow-up by written 
documentation 
11.1 Temporary Treatment Discontinuation 
In this trial, it is expected that subjects may have one or more treatment interruptions 
during the unblind, randomized treatment period.  
If a subject’s IMP treatment must be interrupted for medical or surgical reasons; blood 
safety test abnormalities; use of a prohibited concomitant medication; or other reasons 
(e.g., hospital admission for an invasive procedure, a major medical condition, surgery; 
dental work, or a temporary situation that prevents subject compliance with the IMP 
administration schedule), the subject’s IMP should be resumed as early as the situation 
allows. 

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Any IMP interruption of <10 consecutive days will be recorded as missed doses rather 
than as a temporary interruption of IMP. The subject should immediately inform the 
investigator of any missed doses reaching or expected to be 2 days or more so that the 
investigator can continue to monitor the subject’s treatments and prepare for a possible 
10-day IMP interruption. 
An IMP interruption that lasts >10 consecutive days will be recorded as a “10-day 
Treatment Interruption” on the eCRF and the subject will visit the clinic to collect vital signs 
and physical exam. Treatment may still be restarted during or after these assessments are 
completed. If treatment is restarted, and the subject continues to Month 24, the subject will 
complete the Month 24 visit and scheduled follow-up assessments. 
If treatment does not restart, subjects will complete an EoTx visit then 2 follow-up visits 
(between +8 and +21) must be collected. Assessment at each follow-up visit will include: 
1) Perform physical examination, including post-void body weight and height;  
2) Record medical/PKD history; 
3) Record concomitant medications and ensure subject's treatment meets current standard 
of care including lifestyle and dietary recommendations, especially for ingestion of at least 
2-3 liters of fluid per day as appropriate, unless otherwise directed by study doctor; 
4) Assess AEs, if reported; 
5) Assess vital signs (include heart rate and blood pressure); 
6) Serum pregnancy test for WOCBP (second visit); 
7) Collect urine and blood samples for clinical laboratory analyses, including serum 
creatinine, liver function tests, glucose metabolism parameter, CBC and venous gas 
analysis (second visit). 

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11.2 Permanent Treatment Discontinuation 
After randomization, a subject may stop treatment permanently before Month 24 for a 
variety of reasons. Treatment discontinuations may be initiated by a subject who is not 
satisfied with treatment or may become medically necessary due to AEs or other issues, 
as determined by the investigator. However, each investigator must comprehensively 
review the circumstances and offer the subject options for continued treatment to the 
degree possible. 
A subject who permanently discontinues treatment will be recorded as an IMP 
discontinuation on the eCRF. The subject will then enter the follow-up period as though 
they had reached the Month 24 visit. During the first week of the follow-up period, no 
procedures will be done. During the last two weeks of the follow-up period, the subject will 
have a total of 2 samples collected. 
After the follow-up period, the subject will continue with all assessments up to and 
including their scheduled Month 24 visit, but will not be required to complete follow- up 
beyond that visit. 
 
11.3 Accountability 
The investigator or designee must maintain an inventory record of IMP (including 
investigational, active control, or placebo) received, dispensed, administered, and 
returned. 
 
12. STATISTICAL CONSIDERATIONS 
12.1 Sample Size Determination and Rationale 

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In TEMPO 3:4, tolvaptan reduced the decline in eGFR from 3.70 to 2.72 ml/min per 1.73 
m2 per year (26.5%); P=0.001). A post hoc analysis showed that tolvaptan decreased the 
rate of eGFR decline by 0.40 ml/min per 1.73 m2 per year (95% CI, 20.25 to 1.05; P=0.23) 
in patients with CKD1, by 1.13 (95% CI, 0.61–1.66; P=0.001) in those with CKD2, and by 
1.66 (95% CI, 0.83–2.45; P=0.001) in those with CKD3, with a trend for a positive 
subgroup–treatment interaction (P=0.07). Results for patients in CKD3 were similar when 
split into CKD3a and CKD3b. Tolvaptan treatment effects on eGFR slope were confirmed 
by comparing the eGFR values before treatment at baseline and those after 
discontinuation of study drug, which favored tolvaptan across CKD1 through CKD3. 
Consistent with the beneficial effects of tolvaptan on the rates of eGFR decline, patients 
with CKD2 and CKD3 randomly assigned to placebo were more likely to progress to a 
higher CKD stage at the last follow-up visit than those treated with tolvaptan. 
This study will be based upon recruitment of an opportunistic sample given the rarity of the 
condition and the lack of available studies in the setting. 
We plan to recruit a total of 150 patients which are currently within reach of the network 
coordinated by the proponent and composed by 11 Nephrology Centres. This network 
treats a total of 1500 (already genetically studied) patients of which we expect (based on 
standard response rates recognized in the population) acceptance to participate in the 
study to a value of approximately 40% of patients. These will be then allocated to the 
experimental and control intervention. 
The selected sample is adequate to evaluate a significant reduction in the slope of eGFR 
at 2 years by 10%, which is a clinically relevant piece of information at the current state of 
knowledge, as well as a complete assessment of the benefits-harms trade-off of the two 
interventions. 
 

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12.2 Randomization 
Randomization process will be carried out by a WEB-based, internet-accessible, system 
(e-trial platform). Investigators willing to include a patient should log-in into the e-trial 
platform and complete the registration form. 
12.3 Statistical Methods 
A comparative analysis for the primary outcome will be carried out under the principle of 
'"intention-to-treat" and including data from all subjects who are randomized. The efficacy 
and safety of compared interventions will be assessed. Trial data will be summarized by 
the calculation of means and standard deviations for normally distributed variables, 
medians and interquartile ranges for non-normally distributed variables, and frequency and 
percentage for categorical variables. Missing data will be ignored. The primary and 
secondary outcomes, namely the slope of the annualized eGFR and TKV will be analyzed 
using standard statistics including linear mixed-effects models. A P value <0.05 will be 
deemed significant.There are no plans for interim analyses. 
 
13. ETHICAL CONSIDERATIONS 
13.1 Investigator Responsibilities 
The trial will be conducted in accordance with the requirements of the International 
Conference on Harmonization (ICH), of the Good Clinical Practice (GCP) Guideline and of 
the local regulatory and must adhere to the ethical principles that have their origin in the 
Declaration of Helsinki.  
The Investigator is responsible for ensuring that the clinical study is performed in 
accordance with the protocol, current ICH guidelines on Good Clinical Practice (GCP), and 
applicable regulatory requirements. 

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The Investigator will report promptly to the IEC any new information that may adversely 
affect the safety of subjects or the conduct of the study. Similarly, the Investigator will 
submit written summaries of the study status to the IEC annually, or more frequently if 
requested by the IEC. 
Upon completion of the study, the Investigator will provide the IEC with a brief report of the 
outcome of the study, if required. 
 
13.2 Informed Consent 
Each subject (or a legally acceptable representative) must give written consent according 
to local requirements after the nature of the study has been fully explained. The consent 
form must be signed before performance of any study-related activity. The consent form 
that is used must be approved by reviewing IEC. The informed consent should be in 
accordance with principles that originated in the Declaration of Helsinki, current ICH and 
GCP guidelines, applicable regulatory requirements, and Investigator-Sponsor policy. 
Before entry into the study, the Investigator or an authorized member of the investigational 
staff must explain to potential subjects or their legally acceptable representatives the aims, 
methods, reasonably anticipated benefits, and potential hazards of the study, and any 
discomfort it may entail. Subjects will be informed that their participation is voluntary and 
that they may withdraw consent to participate at any time. They will be informed that 
choosing not to participate will not affect the care the subject will receive for the treatment 
of his/her disease. Subjects will be told that alternative treatments are available if they 
refuse to take part and that such refusal will not prejudice future treatment.  
The subject or legally acceptable representative will be given sufficient time to read the 
informed consent form and the opportunity to ask questions. After this explanation and 

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before entry to the study, consent should be appropriately recorded by means of either the 
subject's or his/her legally acceptable representative's dated signature. After having 
obtained the consent, a copy of the informed consent form must be given to the subject. 
If the subject or legally acceptable representative is unable to read or write, an impartial 
witness should be present for the entire informed consent process (which includes reading 
and explaining all written information) and personally date and sign the informed consent 
form after the oral consent of the subject or legally acceptable representative is obtained. 
Investigators (or whoever required by local regulations) should determine whether or not a 
mentally impaired or incapacitated subject is capable of giving informed consent and 
should sign a statement to that effect. If the subject is deemed mentally competent to give 
informed consent, the investigator should follow standard procedures. If the subject is 
deemed not to be mentally competent to give informed consent, must not be enrolled in 
clinical study. 
 
13.3 Independent Ethics Committee 
Prior to initiation of the study at each site, the protocol, the informed consent form(s), the 
subject information sheet(s), details of the subject recruitment procedures and any other 
relevant study documentation will be submitted to local IEC. At the end of the study, the 
Investigator-Sponsor will notify the IEC about the study completion. 
 
13.4 Amendments to the Protocol 
Modifications of the signed protocol are only possible by approved protocol amendments 
and with the agreement of all responsible persons. The procedure for approval of a 
protocol amendment is identical to that for approval of the protocol. The IEC must be 

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informed of all protocol amendments and should be asked for its opinion as to whether a 
full re-evaluation of the ethical aspects of the study is necessary by the IEC. This should 
be fully documented. 
The Investigator must not implement any deviation from or change to the protocol without 
discussion with and agreement by the Investigator-Sponsor and prior review and 
documented approval/favorable opinion of the amendment from the relevant IEC, except 
where it is necessary to eliminate an immediate hazard to study subjects, or where the 
change(s) involves only logistical or administrative aspects. 
 
13.5 Premature Termination of the Study 
If the study is prematurely terminated or suspended, the Investigator-Sponsor will prompt 
inform the Investigator/Institution and the IEC of the termination or suspension and the 
reason(s) for the termination or suspension. 
 
13.6 Data Protection 
The collection and processing of personal data from subjects enrolled in this study will be 
limited to those data that are necessary to investigate the efficacy, safety, quality, and 
utility of the investigational product(s) used in this study. 
These data must be collected and processed with adequate precautions to ensure 
confidentiality and compliance with applicable data privacy protection laws and 
regulations. 
The Investigator-Sponsor ensures that the personal data will be: 
 processed fairly and lawfully; 

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 collected for specified, explicit, and legitimate purposes and not further processed in 
a way incompatible with these purposes; 
 adequate, relevant, and not excessive in relation to said purposes; 
 accurate and, where necessary, kept current. 
Explicit consent for the processing of personal data will be obtained from the participating 
subject (or his/her legally acceptable representative) before collection of data. Such 
consent should also address the transfer of the data to other entities and to other 
countries. 
The subject has the right to request through the Investigator access to his/her personal 
data and the right to request rectification of any data that are not correct or complete. 
Reasonable steps should be taken to respond to such a request, taking into consideration 
the nature of the request, the conditions of the study, and the applicable laws and 
regulations. 
 
14. STUDY MONITORING 
14.1 Monitoring 
The Investigator-Sponsor, or designee, will perform all monitoring functions within this 
clinical study. Monitors will be responsible for establishing and maintaining regular contact 
between the Investigator and the Investigator-Sponsor. 
 
14.2 Data Confidentiality 
Information about study subjects will be kept confidential and managed under the 
applicable laws and regulations. The data collection system for this study uses built-in 
security features to encrypt all data for transmission in both directions, preventing 

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unauthorized access to confidential participant information. Access to the system will be 
controlled by a sequence of individually assigned user identification codes and passwords, 
made available only to authorized personnel who have completed prerequisite training. 
 
14.3 Audit and Inspection 
Investigator site, the study database and the study documentation may be subject to 
quality assurance audits during the course of the study either by the Investigator-Sponsor 
or his appointed representatives. In addition, regulatory bodies at their discretion may 
conduct inspections. 
 
14.4 Source Documents 
The Investigator shall permit the authorized Investigator-Sponsor, his representatives, and 
regulatory agencies to enter and inspect any site where the drug or records pertaining to 
the drug are held, and to inspect all records relating to an investigation, including subject 
records. Completed eCRFs must be available by the Investigator for review by the 
Investigator-Sponsor, his representatives, the monitor and the regulatory agencies. To 
ensure the accuracy of data submitted, it is mandatory that representatives of the 
Investigator-Sponsor and of the regulatory agencies have direct access to source 
documents (e.g., subject medical records, charts, laboratory reports, etc.). Subject 
confidentiality will be protected at all times. 
 
14.5 Case Report Form 
This study will use an Electronic Data Capture (EDC) system. Investigator site staff will not 
be given access to the EDC system until they have been trained. Automatic validation 

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programs check for data discrepancies in the eCRFs allow modification or verification of 
the entered data by the investigator staff. The Principal Investigator is responsible for 
assuring that the data entered into eCRF is complete, accurate, and that entry and 
updates are performed in a timely manner. The CRF and the protocol are both 
confidential. The CRF will remain the property of the Investigator-Sponsor at all times. 
The Investigator-Sponsor will supply electronic CRFs. All e-CRFs are to be completed and 
reviewed by the Investigator. 
The e-CRFs for any subject leaving the study should be completed at the time medication 
is terminated for whatever reason. 
It is each Investigator’s responsibility to ensure that e-CRFs accurately reflect data 
contained in subject’s records (e.g., source documents). 
 
14.6 Investigator Site File 
At the beginning of the study, an Investigator’s study file will be established at the Center. 
The Investigator/Institution is responsible for maintaining the study documents, as required 
by the applicable regulatory requirements. The Investigator/Institution must take measures 
to prevent accidental or premature destruction of these documents. 
 
14.7 Patient Insurance and Indemnity 
The Investigator-Sponsor will provide the insurance in accordance with local guidelines 
and requirements as a minimum for the patients participating in this study. The terms of 
insurance will be kept in the study files. Subject insurance and the publication policy for the 
trial will be provided and documented according to DM 14 Luglio 2009. 

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14.8 Clinical Study Report 
A final integrated clinical/statistical report will be prepared at the end of the study. 
 
14.9 Disclosure of Information and Results 
In signing the protocol/protocol amendment(s), every participating Investigator agrees to 
keep all information and results concerning the study confidential. The confidentiality 
obligation applies to all personnel involved at each site. 
 
14.10 Publication 
The results of this study will be published and/or presented at scientific meetings. Any 
formal publication of study results will be a collaborative effort between the Investigator-
Sponsor and the Investigators. All manuscripts or abstracts will be reviewed and approved 
in writing by the Investigator-Sponsor prior to submission. 
 
14.11 Archiving and Data Retention 
All study documents should be retained in compliance with the regulatory requirements. 
The final database will be archived by the Investigator-Sponsor according to regulatory 
requirements. 
 
 

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15. FIGURES AND TABLES 
 
 
 

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FIGURE 2 
Anamnesi
Storia clinica medica generale e PKD specifica, revisione terapia, aderenza alle norme dietetiche e comportamentali, parametri vitali.
Anamnesi + PV
Esami Bioumorali
Esame Obiettivo
TAC renale smdc
LEGENDA
4
4
4
1
1
Screening
2W
Titolazione 
3W
RI
1W
Mantenimento
24M
FU
3W
R
R
1
A
2
3
3
3
Esami Bioumorali
A. sCreatinina,
B. PT-INR,
C. Ast, ALT, BLB tot e fraz, sUrea, sFosfato, sGlucsio, Emogasanalisi venosa
D. Emoglobina Glicata
E. βHCG sierica
F. Emocromo completo, Cianocobalamina
G. uACR, uPCR, uMCP-1, uEGF, Insulinemia
Esame Obiettivo
Esame fisico, peso corporeo – in Kg, altezza – in cm(questa solo alla prima visita).
TAC renale smdc
Spessore scansioni: 0.5mm, incremento 0.5mm, tempo di rotazione 0.5s, 120/200 kVp/mAs - da diaframma a sinfisi pubica (ogni centro).
Ricostruzione mediante software Vitrea FX 2.1, Vital Images, Minneapolis, MN USA (centro coordinatore).
1. ESAMI A+B+C+D+E+F+G
2. ESAMI A+C+E
3. ESAMI A+C+D+E+F
4. ESAMI A+B+D+E
5. ESAMI A+C
6. ESAMI A+C+E+F
 
 
 
 
FIGURE 3 
FOLLOW-UP (3W)
VISIT 1
VISIT2 2
TREATMENT (4W+24 M)
TITRATION (3W)
RUN-IN (1W) 
MANTENIMENTO (24 M)
RECRUITMENT(9 M)
SCREENING (2W)
ADDITIONAL SCREENING (8W)
RANDOMIZATION
END OF TREATMENT
 
 
 
 
 
 
 

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96 
 
 
 
FIGURE 4 
 
GRUPPO B:
TOLVAPTAN 90 mg+30 mg/die
GRUPPO A: 
METFORMINA 500 mg x 3/die
D -5
M6
TITOLAZIONE
(3 SETTIMANE)
MANTENIMENTO
(24 MESI)
D-21
D -7
M3
M12 M15 M18
M9
M21
R
E
C
L
U
T
A
M
E
N
T
O
9
M
F
O
L
L
O
W
-
U
P
3
W
D -2
M24
RA
D -28
D-14
RUN-IN
(1 SETTIMANA)
90/30 mg (B)
500/500/500 mg (A)
500 mg
500/500 mg
500/500/500 mg
45/15 mg
60/30 mg
90/30 mg
0
 
 
 
 
 
 
 
 
 
 
TABLE 1 
Boceprevir 
Clrithromycin 
Clotrimazole 
Indinavir 
Itraconazole 
Ketoconazole 
Lopinavir 
Mibefradil 
Nefazodone 
Nelfinavir 
Posaconazole 
Ritonavir 
Saquinavir 
Telepravir 
Telithromycin 
Voriconazole 
 
 
 
 
 

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97 
 
 
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