The COMBINE Study: The CKD Optimal Management With BInders and NicotinamidE
Phase: PHASE2
Conditions: Chronic Kidney Disease
Sponsor: The Cleveland Clinic

 
 
 
Pilot Clinical Trials in CKD 
 
EFFECTS OF NICOTINAMIDE AND LANTHANUM 
CARBONATE ON SERUM PHOSPHATE AND FGF23 LEVELS 
IN PATIENTS WITH STAGE 3-4 CHRONIC KIDNEY DISEASE 
 
The CKD Optimal Management with BInders and NicotinamidE: 
COMBINE STUDY 
 
COMBINE Protocol Version 1.2  
June 22, 2015 
 
 
 
 
 

COMBINE PROTOCOL Version 1.2 – 06/22/2015 
Page 1 of 25 
 
EFFECTS OF NICOTINAMIDE AND LANTHANUM CARBONATE ON SERUM PHOSPHATE 
AND FGF23 LEVELS IN PATIENTS WITH STAGE 3-4 CHRONIC KIDNEY DISEASE 
Pilot Clinical Trials in CKD.......................................................................................................... 1 
EFFECTS OF NICOTINAMIDE AND LANTHANUM CARBONATE ON SERUM PHOSPHATE 
AND FGF23 LEVELS IN PATIENTS WITH STAGE 3-4 CHRONIC KIDNEY DISEASE ............. 1 
1 
INTRODUCTION ................................................................................................................ 3 
1.1 
Executive Summary ..................................................................................................... 3 
1.2 
Background.................................................................................................................. 4 
1.3 
Goals/Aims/Hypotheses ............................................................................................... 4 
1.4 
Description of the treatments being tested ................................................................... 5 
1.5 
Design of this Pilot Clinical Trial ................................................................................... 5 
1.6 
Sample Size for this Pilot Clinical Trial ......................................................................... 6 
1.7 
Timeline for this Pilot Clinical Trial ............................................................................... 7 
1.8 
Patient Timeline (Key events of Screening, Baseline, Randomization, Follow-up) – 
Table 1 ................................................................................................................................... 8 
2 
PATIENT SELECTION .......................................................................................................10 
2.1 
Introduction .................................................................................................................10 
2.2 
Inclusion and Exclusion Criteria ..................................................................................10 
2.3 
Identification of participants for screening ...................................................................11 
2.4 
Informed Consent Procedures ....................................................................................11 
2.4 
Informed Consent Procedures ....................................................................................11 
2.5 
Privacy and security ....................................................................................................12 
3 
BASELINE PERIOD EVALUATION ...................................................................................12 
3.1 
Introduction .................................................................................................................12 
3.2 
Baseline collection of concurrent meds at study entry .................................................12 
3.3 
Comorbidity assessment .............................................................................................12 
3.4 
Description of run in ....................................................................................................13 
3.5 
Compliance assessment .............................................................................................14 
3.6 
Maximum time allowed in baseline ..............................................................................14 
3.7 
Collecting reasons for baseline drop out .....................................................................14 
3.8 
Assessment of readiness for randomization ................................................................14 
4 
RANDOMIZATION AND RECRUITMENT MONITORING ..................................................14 
4.1 
Randomization in an intent-to-treat clinical trial ...........................................................14 
4.2 
Logistics of randomization ...........................................................................................14 
4.3 
How recruitment will be monitored ..............................................................................15 
5 
TREATMENT ARMS ..........................................................................................................15 
5.1 
Initiation of treatment ..................................................................................................15 
5.2 
Dose adjustments and treatment stops related to serum phosphate levels .................16 
5.2.1 
Dose adjustment due to hypophosphatemia ........................................................16 
5.2.2 
Treatment safety medication stop due to hyperphosphatemia .............................16 
5.2.3 
Dose adjustments due to intolerable GI or other side effects ...............................17 
5.3 
Management of dose adjustments of study drugs in the presence of other medications
 
17 
5.4 
Supply of treatment .....................................................................................................17 
5.5 
Resupply of treatment .................................................................................................17 
5.6 
Maintaining blinding ....................................................................................................17 
5.7 
Unblinding ...................................................................................................................17 
6 
FOLLOW-UP PERIOD EVALUATION ................................................................................17 
6.1 
Follow-up visit schedule and schedule of tests done during follow-up .........................17 
6.1.1 
Overview ..............................................................................................................17 
6.1.2 
Description of procedures during in-person visits .................................................17 

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6.2 
Monitoring compliance to treatment ............................................................................18 
6.3 
Procedures for patients who start dialysis or undergo kidney transplantation ..............18 
6.4 
Procedures for patients who become pregnant ...........................................................18 
7 
CHARACTERIZATION OF THE MEASUREMENTS AND PROCEDURES DURING 
SCREENING, BASELINE, AND FOLLOW-UP AND METHODS OF MEASUREMENT TO BE 
USED ........................................................................................................................................18 
7.1 
GFR Calculation .........................................................................................................18 
7.2 
List of laboratory measurements .................................................................................19 
8 
ADVERSE EVENTS, ADVERSE EVENT REPORTING .....................................................19 
8.1 
Introduction .................................................................................................................19 
8.2 
Expected Study Adverse Events .................................................................................19 
8.2.1 
Types of AEs that may be treatment or procedure side effects ............................19 
8.2.2 
How AEs will be reported .....................................................................................20 
8.2.3 
Follow-up of AEs ..................................................................................................20 
8.3 
SAE, Hospitalization, and Death reporting ..................................................................20 
8.3.1 
Local Categorization of SAEs as Unanticipated, Related .....................................20 
8.3.2 
Event Committee Review of SAEs .......................................................................20 
9 
STOPPING RANDOMIZED TREATMENT .........................................................................21 
9.1 
Stopping randomized treatment for Adverse Events ...................................................21 
9.2 
Stopping randomized treatment for Adverse Events ...................................................21 
9.3 
Discontinuation of study medications due to patient preference/non-compliance ........21 
9.4 
The role of Study Committees in review of lab data and adverse events .....................21 
10 
DSMB .............................................................................................................................21 
11 
ANALYSIS PLAN ...........................................................................................................21 
11.1 
Primary analysis .........................................................................................................21 
11.2 
Secondary Analyses ...................................................................................................22 
11.3 
Analyses of other follow-up data .................................................................................22 
11.4 
Safety analyses ..........................................................................................................22 
11.5 
Planned analyses of feasibility/logistics including rates of missing data, missing forms,  
missing visits, and of non-compliance....................................................................................23 
11.6 
What will it take to say that this pilot study is feasible? ................................................23 
11.7 
Test run of the analysis plan for the full scale study ....................................................23 
12 
PLANS FOR THE STUDY DESIGN OF THE FULL SCALE TRIAL ................................23 
12.1 
Current Plans for Primary Outcome of the Full Scale Trial ..........................................23 
13 
ACKNOWLEDGEMENTS ...............................................................................................23 
14 
REFERENCES ...............................................................................................................23 
 
 
 
 

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1 
INTRODUCTION 
1.1 
Executive Summary   
Chronic kidney disease (CKD) is a major public health problem1 that impairs functional status, shortens 
lifespan and consumes healthcare resources.  CKD is complicated by disordered mineral metabolism, 
characterized by abnormalities in calcium and phosphate homeostasis, calcitriol deficiency and increased 
parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) levels.2,3  Observational studies 
report strong associations between disordered mineral metabolism and risks of end-stage renal disease 
(ESRD), cardiovascular disease (CVD), fractures, and death.4-6  Experimental data suggest that arterial 
stiffness and left ventricular hypertrophy (LVH) may serve as useful intermediate endpoints for CVD 
outcomes in CKD patients.  Phosphate excess promotes vascular calcification leading to arterial 
stiffness,7,8 and FGF23 excess exerts hypertrophic effects on the myocardium, contributing to LVH.9,10  
Thus, interventions that lower phosphate and FGF23 may reduce risks of morbidity and mortality in 
CKD.   
Prior to embarking on a large randomized controlled trial to test the impact of phosphate and FGF23 
reduction on hard clinical endpoints in CKD, additional data are needed on the effects of proposed 
interventions on serum phosphate and FGF23 levels.  In this pilot study, a 12-month, randomized, double-
blinded, four arm parallel study in 200 CKD patients with eGFR between 20 and 45 ml/min/1.73m2 will 
be conducted.  Participants will be randomized to one of the four groups: 1) lanthanum carbonate + 
nicotinamide; 2) lanthanum carbonate + nicotinamide placebo; 3) lanthanum carbonate placebo + 
nicotinamide; 4) lanthanum carbonate placebo + nicotinamide placebo. 
The Specific Aims for this protocol are:  
Specific Aim 1: Determine the efficacy of nicotinamide and lanthanum carbonate on serum phosphate 
and FGF23 levels in CKD stage 3-4:   
Primary hypothesis: Compared to placebo, monotherapy with nicotinamide, monotherapy with lanthanum 
carbonate, and combined nicotinamide and lanthanum carbonate therapy will lower serum phosphate and 
FGF23 levels.  
Secondary hypothesis: Combined active therapy with nicotinamide and lanthanum carbonate will lower 
serum phosphate and FGF23 levels more than nicotinamide alone or lanthanum carbonate alone. 
Specific Aim 2: Determine the safety and tolerability of nicotinamide and lanthanum carbonate in CKD 
stage 3-4:   
Hypothesis: Combined treatment with nicotinamide and lanthanum carbonate will be safe, well-tolerated, 
and acceptable to CKD participants, demonstrating feasibility of long-term compliance in a subsequent 
phase 3 clinical trial. 
The secondary objectives of this pilot clinical trial are to evaluate the following: 
1. The effects of active therapy with nicotinamide and lanthanum carbonate compared to placebo on 
bone and mineral metabolism markers in patients with Stage 3-4 CKD, as assessed by changes in 
PTH, calcitriol, klotho, N terminal propeptide of Type 1 procollagen (P1NP)  and tartrate-resistant 
acid phosphatase (TRAP) 5b levels over 12 months. 
2. The effects of active therapy with nicotinamide and lanthanum carbonate compared to placebo on 
surrogate measures of CVD risk in patients with Stage 3-4 CKD, as assessed by gadolinium-free 
Cardiac Magnetic Resonance Imaging (MRI)-measured changes in left ventricular (LV) mass index, 
LV end diastolic volume, left atrial volume, and levels of brain natriuretic peptide (BNP), troponin T, 
cholesterol, and asymmetric dimethylarginine (ADMA) over 12 months. 
3. The effects of active therapy with nicotinamide and lanthanum carbonate compared to placebo on 
surrogate measures of CKD progression and inflammation with Stage 3-4 CKD, as assessed by 
changes in intra-renal oxygenation and fibrosis as measured by gadolinium-free blood oxygenation 

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level dependent (BOLD) MRI and diffusion-weighted MRI and changes in GFR, albuminuria and 
CRP and IL-6 over 12 months. 
1.2 
Background  
Disordered mineral metabolism is a near-universal complication of CKD2,3 and is strongly linked to risks 
of ESRD, CVD, fractures, and death.4-6  Phosphate excess induces arterial calcification,7 which is an 
important phenotype of CVD in CKD.  Elevated FGF23 maintains serum phosphate in the normal range 
in CKD, but FGF23 excess contributes mechanistically to LVH.9  Both phosphate and FGF23 excess are 
associated with CVD and CKD progression,6 and data in laboratory animals suggest causal links.7,9  
Therefore, our over-arching hypothesis is that interventions targeting phosphate and FGF23 excess in 
CKD stages 3–4 will reduce risks of ESRD, CVD, fractures, and death.   
Small studies suggest that phosphate binders and dietary phosphate modification may lower FGF23 and 
phosphate, and improve other indices of mineral metabolism and vascular biology in CKD.11   
Nicotinamide (vitamin B3, also called niacinamide) lowers serum phosphate levels in animals12 and in 
patients with ESRD.13-16  Rather than binding dietary phosphate, nicotinamide reduces expression of 
NPT2b,12 the major sodium-phosphate co-transporter in the small bowel.  Animal studies demonstrate that 
NPT2b is upregulated when dietary phosphate intake is decreased or when phosphate binders are 
administered.12,17  As a result, attempts to reduce dietary phosphate absorption using phosphate binders 
alone may be limited by upregulation of sodium-phosphate transporters and resultant increases in dietary 
phosphate absorption at times when phosphate binders are not present in the intestinal lumen.  Therefore, 
we hypothesize that use of nicotinamide combined with phosphate binders will provide the most effective 
method to reduce phosphate and FGF23 levels and related risks of ESRD, CVD, fractures, and death in 
CKD patients. 
1.3 
Goals/Aims/Hypotheses 
Our long-term goal is to conduct a placebo-controlled, randomized trial to target phosphate and FGF23 
excess.  Hard end-points will include a combination (to be determined) of ESRD, CVD events, fractures 
and death.  The purpose of this pilot study is to determine whether intervention with both nicotinamide 
and phosphate binders, in either isolation or in combination will provide an efficacious, safe, well 
tolerated and feasible strategy to advance into the large outcomes trial.     
A 12-month, randomized, double-blinded, four-arm parallel study in 200 CKD stage 3–4 patients will be 
conducted.  Participants will be randomized to one of the four groups: 1) lanthanum carbonate + 
nicotinamide; 2) lanthanum carbonate + nicotinamide placebo; 3) lanthanum carbonate placebo + 
nicotinamide; 4) lanthanum carbonate placebo + nicotinamide placebo. 
The following hypotheses will be tested: 
1.  Compared to placebo, monotherapy with nicotinamide, monotherapy with lanthanum carbonate, and 
 
combined nicotinamide and lanthanum carbonate therapy will lower serum phosphate and FGF23 
 
levels. 
2.  Combined treatment with nicotinamide and lanthanum carbonate will be safe, well-tolerated, and 
 
acceptable to CKD participants, demonstrating feasibility of long-term compliance in a subsequent 
 
phase 3 clinical trial. 
Secondary hypotheses:  
1) Combined active therapy with nicotinamide and lanthanum carbonate will lower serum phosphate 
and FGF23 levels more than nicotinamide alone or lanthanum carbonate alone. 
2) Compared with placebo, active therapy with nicotinamide and lanthanum carbonate will blunt the 
slope of PTH rise, attenuate the decline of calcitriol and klotho levels, and improve bone turnover 
markers, P1NP and Trap-5b. 

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3) Compared with placebo, active therapy with nicotinamide and lanthanum carbonate will reduce 
or blunt the increase in LV mass index; attenuate LV diastolic dysfunction, indicated by increased 
LV end diastolic volume and decreased left atrial volume (all measures assessed by gadolinium-
free Cardiac MRI); and reduce levels of biomarkers that are associated with CVD: BNP, troponin 
T, cholesterol, and ADMA. 
4) Compared with placebo, active therapy with nicotinamide and lanthanum carbonate  will blunt 
the slope of decline in GFR and the rise in proteinuria and the inflammatory markers, CRP and 
IL-6, improve intra-renal oxygenation and stabilize or reduce progression of renal fibrosis, as 
assessed by gadolinium-free renal BOLD MRI.  
1.4 
Description of the treatments being tested 
Nicotinamide: Animal studies12 and pilot studies in humans show that nicotinamide substantially lowers 
serum phosphate levels, and can do so with only 1-2 pills/day.13-16  Nicotinamide reduces serum 
phosphate levels by blocking intestinal phosphate absorption through down-regulation of NPT2b.12  The 
lipid drug niacin contains both nicotinamide and nicotinic acid,  and it has been shown that it lowers 
serum phosphate in CKD patients.18  However, nicotinamide alone may have advantages over niacin.  
Unlike niacin, nicotinamide does not cause flushing and is thought to be less likely to cause liver test 
abnormalities, hyperuricemia, or insulin resistance.  Nicotinamide has considerable long-term safety data 
in the general population and is available over the counter as a dietary supplement in the US.  The use of 
nicotinamide at a dose of 750 mg once daily during the first month following randomization, followed by 
up-titration to 750 mg twice daily thereafter is proposed.   
Phosphate binders: Several studies suggest that calcium-based binders do not lower FGF23.19,20  
Therefore, active therapy will consist of fixed doses of lanthanum carbonate (3000 mg/day), which will 
be off patent by 2017.  Use lanthanum carbonate at a dose of 500 mg three times daily with meals during 
the first month following randomization and a 1000 mg three times daily with meals thereafter is 
proposed.  This fixed dose was chosen because it has been demonstrated that this dose safely reduced 
urinary phosphate, signifying effective phosphate binding, in CKD stages 34.20,21  Importantly, 
lanthanum carbonate has been used in the hemodialysis population, with 6-year long safety data 
demonstrating a good safety profile.22  Participants who do not eat regular meals will be instructed to take 
full doses with larger meals and half with snacks.   
An IND exemption from the FDA has been applied and received for the use of both of these agents alone 
and in combination for this trial.   
Dietary phosphate restriction: In all study arms, during the run-in phase, dietary information will be 
provided to participants to reduce dietary phosphate intake.  The study coordinator will provide this 
information, which will include: a) instructions on how to read food labels in order to avoid foods with 
phosphate additives23; b) advice to reduce serving sizes of animal protein; c) encouragement of 
consumption of vegetarian sources of protein instead of animal protein; d) advice to reduce consumption 
of dairy, and e) encouragement of consumption of egg whites instead of egg yolks.  Prior proof-of-
concept data demonstrated feasibility of this approach and the importance of this adjunctive intervention 
to potentiate the efficacy of phosphate binders in lowering serum phosphate and FGF23 levels.11       
1.5 
Design of this Pilot Clinical Trial  
This is a 12-month, randomized, double-blinded, four arm parallel study in 200 CKD stage 3–4 patients 
(50 in each of the four treatment groups) investigating the effects of the interventions on changes in serum 
phosphate and FGF23 levels.  Participants will be randomized to one of the four groups: 1) lanthanum 
carbonate + nicotinamide; 2) lanthanum carbonate + nicotinamide placebo; 3) lanthanum carbonate 
placebo + nicotinamide; 4) lanthanum carbonate placebo + nicotinamide placebo.  
The COMBINE Study is a multi-center clinical trial being carried out by the NIDDK-funded Pilot 
Clinical Trials in CKD Consortium.  Participants will be enrolled at each of the core clinical centers 

COMBINE PROTOCOL Version 1.2 – 06/22/2015 
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(George Washington University; Northwestern University; University of California San Diego/Denver 
Nephrology; University of Utah). 
1.6 
Sample Size for this Pilot Clinical Trial  
Assumptions based on prior studies:  
 
In our pilot trial in CKD,18 niacin lowered serum phosphate by 0.42 mg/dL relative to placebo.  This 
magnitude of effect occurred within 2 months and was stable for the remainder of the 6-month 
study.18  Thus, it is anticipated that a similar magnitude of effect in the proposed study despite the 
longer follow-up time proposed in this study.  The within group standard deviation of change in 
serum phosphate over 6 months was 0.55 mg/dL 
 
In our prior unpublished data, the within group standard deviation for the change in FGF23 levels in 
untreated individuals over 2 years was 18.65 pg/ml. 
Power justification:  
This pilot study is powered to demonstrate both a decrease in serum phosphate and a decrease in FGF23 
levels.  Specifically, the primary hypotheses for these two primary end points will compare each of the 
three treatment groups to placebo.  To control for three comparisons and two primary end points, 
Bonferroni correction is applied by dividing the standard α of 0.05 by 6 to yield a two-sided α of 0.0083.  
Using this conservative method for correction of multiple testing, an estimated sample size of 43 
participants per group will yield 80% power to detect a difference of 0.42 mg/dl in serum phosphate, at 
α=0.0083, assuming a within group SD of the change in serum phosphate over time of 0.55 mg/dL.  The 
same sample size of 43 participants per group will allow detection of a difference of 14.3 pg/ml in 
FGF23, with 80% power, at α=0.0083, assuming a SD of the change of 18.65 pg/ml. 
Fifty participants per arm will be enrolled to provide a reasonable buffer from drop-outs (~14% drop out 
rate).   Importantly, our power calculations are based on t-tests that compare pre to post intervention 
changes across two groups.  Because the repeated measures analyses employed using linear mixed models 
will reduce within-subject variability, there will be greater power than is tabulated above and the 
presented power calculations are conservative estimates. 
Sample size for the secondary objectives:  
To maximize power for the secondary objectives analyses, change over time in the outcome measures in 
all actively treated vs. placebo-treated participants (3:1) will be compared.  With this approach, we 
anticipate having sufficient power for all end points proposed under secondary objectives.  
In a previous study of CKD patients with comparable GFR,19 PTH levels declined by 35.5%, from 107 
pg/ml to 69 pg/ml by 6 weeks among the 21 participants treated with sevelamer hydrochloride.  In our 
previous study, the within group standard deviation (SD) for % change in PTH over 3 months was 42%.  
With our planned analysis being the comparison of all actively treated vs. placebo-treated participants 
(3:1), assuming a conservative SD of the change of 45%, 150 actively-treated and 50 placebo-treated 
individuals will allow us to detect a difference in % change in PTH as small as 21% in response to active 
treatment with 80% power at a two-sided α=5%.  Keeping all assumptions the same but changing the SD 
to 50% yields a minimum detectable difference of 23%, which will decrease to 22.2% for a possible 14% 
drop out rate.  Importantly, our power calculations are based on t-tests that compare pre to post 
intervention changes across two groups.  Because the repeated measures analyses employed using linear 
mixed models will reduce within-subject variability, there will be greater power than is tabulated above 
and view the presented power calculations as conservative estimates. 
It is anticipated that the sample size for the MRI studies will be approximately 70% of the total sample 
size (n=140) because of contraindications (pacemakers, metal fragments, and claustrophobia) and 
participant refusal.  It is believed that this estimate is conservative, given that > 70% of enrolled 
participants in the NHLBI-sponsored Multi-Ethnic Study of Atherosclerosis successfully completed the 
MRI measurements.24  A 2-sided t-test to calculate the power to detect a significant difference from 

COMBINE PROTOCOL Version 1.2 – 06/22/2015 
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baseline to end of study in change in LVMI between 105 actively-treated and 35 placebo-treated 
participants was used.  For our estimate of the within-subject SD for change in LVMI over time, data on 
repeated measures of LVMI by MRI from the PRIMO study was used, which was a randomized trial of 
paricalcitol in patients with a similar range of eGFR as in the COMBINE study.  In the 91 placebo-treated 
PRIMO participants, the SD for the change in LVMI over 48 weeks was 2.4 g/m2.7.25  Assuming a SD of 
the change of 2.4 g/m2.7, 105 actively-treated and 35 placebo-treated individuals will allow us to detect a 
difference in change in LVMI as small as 1.3 g/m2.7 in response to active treatment with 80% power at a 
two-sided α=5%.  Eighty percent power for change in LVMI if 124 participants (93 active-treated and 31 
placebo) are enrolled and provide at least one baseline and one follow-up MRI examination will be 
maintained.  Keeping all assumptions the same but allowing for a more conservative SD of 3.0 g/m2.7 will 
enable us to detect a difference in change in LVMI as small as 1.7 g/m2.7.  A difference of ~3.0 g/m2.7 is 
considered to be a clinically meaningful between-group difference in LVMI and corresponds to a mean 
between-group difference of ~10 g in LVM.25,26  The study will have >90% power to detect a difference 
of this magnitude, assuming a SD of the change of 2.4 – 3.0 g/m2.7.     
Since there are no studies with repeated measures of BOLD MRI in CKD, we relied on collaborators’ 
cross-sectional data to calculate the power for our proposed analyses in Aim 3.  Assuming a common SD 
of 10 s-1, a conservative correlation of repeated R2* measures of 0.5, and a two-sided α of 5%, 105 
participants in the actively-treated arm and 35 participants in the placebo arm will allow us to detect a 
difference between the groups in R2* as small as 4.5 s-1 with 80% power.  Keeping all assumptions the 
same, but changing the SD to 15 s-1 yields a minimal detectable difference of 6.4 s-1. 
1.7 
Timeline for this Pilot Clinical Trial 
The study will include the following 3 phases:  
1. Screening Period  
2. Baseline and Run-in Period  
3. Follow-up Period 
A 2-week run-in will be included in the 3-week long Baseline Period.  During the run in, compliance with 
the nicotinamide placebo and lanthanum carbonate placebo, visits, and procedures will be assessed.  
During the run-in, a first visit will occur to dispense placebo pills, followed by 2 visits one week apart.  
After participants meet all inclusion criteria, screening requirements and MRI safety criteria, pre-
randomization cardiac and BOLD renal MRI will be obtained. These baseline imaging studies should be 
performed anytime between Baseline Visit 0 (B0) and prior to Baseline Visit 2 (B2).  The optimal timing 
of the baseline MRI scans is prior to B2, but the studies may occur up to two calendar months after B2. 
Thereafter, follow-up visits will take on the following schedule:  
o monthly visits for the first 3 months (months 1-3) 
o visits every 3 months from month 3 (months 3-12), with an extra visit at month 11 
A timeline of the key events in the study is shown in Table 1 below.  
 

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1.8 
Patient Timeline (Key events of Screening, Baseline, Randomization, Follow-up) – Table 1 
 
Periods 
SCREENING 
BASELINE/RUN-IN 
FOLLOW-UP 
Visits 
 S0 
B0 
B1 
B2/F0 
F1 
F2 
F3 
F6 
F9 
F11 
F12 
Months (unless otherwise specified) 
-3 weeks 
-2 weeks 
-1 weeks 
0 weeks 
1 
2 
3 
6 
9 
11 
12 
Pregnancy testing 
X 
 
 
 
 
 
 
 
 
 
 
Distribute placebos for run in and measure 
height 
 
X 
 
 
 
 
 
 
 
 
 
Distribute drug/placebo (X = 30 day supply) 
 
 
 
X 
X 
X 
XXX 
XXX 
XX 
X 
 
Demographics, medical history 
X 
 
 
 
 
 
 
 
 
 
 
BP, pulse, weight 
X 
 
X 
X 
 
 
X 
X 
X 
 
X 
Dietary information and adherence 
reinforcement 
 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
PTH 
X 
 
X 
X 
 
 
X 
X 
X 
 
X 
Serum calcium 
 
 
X 
X 
 
 
X 
X 
X 
 
X 
Spot urine phosphate, calcium, creatinine, and 
albumin 
 
 
X 
X 
 
 
X 
X 
 
 
X 
24-hr urine phosphate, calcium, creatinine,  and 
urea nitrogen 
 
 
X 
X 
 
 
X 
X 
 
 
X 
 
Renal parameters 
Chem 7 (Na, K, Cl, HCO3, BUN, Cr, glucose)  
X 
 
X 
X 
X 
X 
X 
X 
X 
 
X 
Serum uric acid 
 
 
X 
 
 
 
 
X 
 
 
X 
Whole blood HbA1c 
 
 
X 
 
 
 
 
 
 
 
 
Blood samples for FGF23 
 
 
X 
X 
X 
X 
X 
X 
X 
 
X 
Biorepository blood samples 
 
 
X 
X 
 
 
X 
X 
 
 
X 
Biorepository urine samples 
 
 
X 
X 
 
 
X 
X 
 
 
X 
 
Safety assessments 
Serum phosphate 
X 
 
 
 
X 
X 
X 
X 
X 
 
X 
Hemoglobin, Platelets, LFTs, CK (Local)1 
X 
 
 
 
 
 
 
CBC, LFTs, CK (Central) 
 
 
 
 
X 
X 
X 
X 
X 
 
X 
Adverse events assessment 
 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Compliance questions 
 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Pill Counts 
 
 
X 
X 
X 
X 
X 
 
 
 
X 
GI symptoms questionnaire 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Cardiac and BOLD renal MRI 
 
 
X 
 
 
 
 
  
 
 
X 
Bone and mineral metabolism markers2 
 
 
X 
 
 
 
 
X 
 
 
X 
CVD biomarkers3 
 
 
X 
 
 
 
 
X 
 
 
X 
Inflammation biomarkers4 
 
 
X 
 
 
 
 
X 
 
 
X 

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Notes for Table 1: 
S0: screening visit 
B: baseline visit; baseline visits are 1-2 weeks apart 
F: follow-up visits 
X: This evaluation/procedure applies at this visit 
 
1With the exception of screening tests, which will be performed locally, all other tests will be performed at a central lab. 
FGF23, serum phosphate, PTH, CBC, serum calcium, 24-hr and spot urinary phosphate, serum creatinine, UACR, 24-hr urine creatinine and urea, 
uric acid, and HbA1c will be performed centrally as received or in batches.  
 
2Bone and mineral metabolism markers include calcitriol, klotho, P1NP and Trap-5b (performed centrally in batches). 
 
3CVD biomarkers include BNP, troponin T, cholesterol, and ADMA (performed centrally in batches). 
 
4Inflammation markers include CRP and IL-6 (performed centrally in batches). 
 
Please see appendix for volumes of blood drawn at each visit.  

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2 
PATIENT SELECTION 
2.1 
Introduction 
CKD stage 3b–4 patients will be recruited.   All inclusion and exclusion criteria will be based on 
measurements and questionnaires obtained at the screening visit.  Labs will be run in the local lab to 
allow final determination of eligibility with rapid turn-around time. 
2.2 
Inclusion and Exclusion Criteria 
Inclusion criteria:  
1.  
Patients with eGFR 20-45 ml/min/1.73m2  
2.  
Age >18 years 
3.  
Serum phosphate ≥ 2.8 mg/dL 
4.  
Platelet count ≥ 125,000/mm3 
5.  
Able to provide consent 
6.  
Able to travel to study visits  
7.   
Able to eat at least two meals a day 
8.       In the opinion of the site investigator, willing and able to follow the study treatment regimen and  
 
 
comply with the site investigator’s recommendations. 
 
Exclusion criteria:  
1. 
History of allergic reaction to nicotinamide, niacin (excluding flushing), multivitamin 
preparations, or lanthanum carbonate 
2. 
Liver disease, defined as known cirrhosis by imaging or physician diagnosis, documented alcohol 
use > 14 drinks/week, or aspartate aminotransferase (AST), alanine aminotransferase (ALT), 
alkaline phosphatase, or total bilirubin concentrations > 2 times the upper limit of the local 
laboratory reference range 
3. 
Creatine kinase (CK) concentrations > 2 times the upper limit of the local laboratory reference 
range 
4. 
Major hemorrhagic event within the past six months requiring in-patient admission 
5. 
Blood or platelet transfusion within the past six months 
6. 
Secondary hyperparathyroidism (PTH > 5 times the upper limit of normal range for the 
laboratory) or currently taking cinacalcet (Sensipar) 
7. 
Current, clinically significant malabsorption, as determined at the discretion of the site 
investigator 
8. 
Anemia (screening Hg < 9.0 g/dl) 
9. 
Serum albumin < 2.5 mg/dl  
10. 
Anticipated initiation of dialysis or kidney transplantation within 12 months as assessed by and at 
the discretion of the site investigator. 
11. 
Use of immunosuppressive medications.  (This criterion excludes anyone who has received a 
solid organ transplant. Stable oral steroids ≤ 10 mg of prednisone/day or inhaled steroids are 
exempted.)  
12. 
In the opinion of the site investigator, active abuse of alcohol or drugs 
13. 
Recent (within the last 14 days) initiation or change in dose of treatment with 1,25 (OH)2 vitamin 
D or active vitamin D analogues (paricalcitol or hectorol).  Patients on stable doses of these 
agents initiated more than 14 days prior to screening are eligible to participate.  
14. 
Current or recent treatment (within the last 14 days) with phosphate binder or niacin/nicotinamide 
> 100 mg/day 
15. 
Current participation in another clinical trial or other interventional research 
16. 
Currently taking investigational drugs 
17. 
Institutionalized individuals, including prisoners and nursing home residents 
18. 
Malignancy requiring therapy within 2 years (basal or squamous cell skin carcinoma and 
localized prostate cancer are exempted) 

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19. 
Pregnancy or planning to become pregnant or currently breast-feeding.  Women of childbearing 
potential (pre-menopausal and not surgically sterilized) will have pregnancy test before 
enrollment. 
20. 
Life expectancy < 12 months as determined by the site investigator. 
21. 
Hospitalization within the past 30 days prior to Screening visit (24 hour observation admissions 
are exempted) 
22. 
Plans to leave the immediate area within 12 months 
23. 
Eat less than 2 meals a day 
24. 
Routinely leaves town for multiple weeks each year such that protocol visits would be missed 
In addition to the inclusion/exclusion criteria, at the Screening Visit participants will also be asked 
questions listed on the MRI safety screening form.  These questions will also be reviewed immediately 
before MRI scanning on the days of the MRI visits.  Participants who meet all of the inclusion criteria and 
none of the exclusion criteria and who have a contraindication for the MRI will not undergo the imaging 
studies but will proceed with all other study procedures. 
2.3 
Identification of participants for screening 
Sites may use some or all of the following recruitment strategies: clinic-based recruitment; referrals from 
providers; community-based recruitment campaigns.  Brief descriptions of steps taken with each method 
are listed below.  
Clinic-based recruitment:  
 
After HIPAA waivers and waivers of Informed Consent are obtained, if required by local Institutional 
Review Boards, electronic medical records will be reviewed to identify potential patients who are 
eligible for participation.   
 
Study staff will approach patients during their clinic sessions and invite them to learn more about the 
study. Recruitment letters may also be used instead of verbal contact during the course of providing 
medical care. Following introduction, study staff will communicate with interested individuals and set 
up a screening visit.  
Referral from providers: 
Providers will be introduced to the study and will be provided with list of inclusion and exclusion criteria. 
The primary providers will be encouraged to discuss the study with potentially eligible participants, and 
to either provide the participant with contact information for the study, or alternative ask if study 
personnel may contact the participant to discuss the study in more detail. Study staff will initiate contact 
with interested and potentially eligible patients and describe the study to them. Recruitment letters may 
also be used instead of phone contact. Following introduction, study staff will set up screening visits with 
interested individuals. 
Community-based recruitment:     
The site investigators will initiate contact with community leaders and introduce them to the study. 
Community leaders will suggest possible ways to disseminate information regarding the study to potential 
participants in the community. Study staff will respond to contact initiated by interested individuals and 
briefly describe the study to them. Following introduction, study staff will communicate with interested 
individuals and set up a screening visit. Additional strategies, including targeted mailings, advertisements 
within healthcare settings and external promotions will also be considered.   
2.4 
Informed Consent Procedures 
2.4   Informed Consent Procedures 
All participants will provide informed consent.  Participants will be given ample time to review the 
consent and ask questions and will be told that participation in the study is entirely voluntary.  They will 
also be told that if they choose not to participate in the study their care will in no way be affected.   
 

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Consent discussions:  
Discussions regarding consent will occur in either a private exam room or in private research offices.  In 
either case, these discussions will occur behind closed doors for both privacy and to allow the participant 
time to focus on the consent without distractions.  Participants will be asked to describe what they 
understand about the study protocol after their review to assure accurate understanding, and will be given 
the opportunity to take the consent home to read and/or discuss with family members or other health care 
providers before consenting, if they so choose. 
 
Consent and Withdrawal of Consent for the NIDDK Biosample Repository: 
Participants may consent or withdraw consent for the repository at any time during the COMBINE Study.  
If a participant consents to the NIDDK biosample repository, his or her samples will stored at the NIDDK 
biosample repository indefinitely. A participant may withdraw consent for the repository during the study 
by notifying the COMBINE physician at his site.  This physician will notify the DCC staff of this request 
in writing.  The DCC will then notify the repository.  The repository will first obtain approval from 
NIDDK to destroy the samples and then discard the samples with its biological and laboratory waste. The 
DCC will follow through to make sure the samples have been destroyed.  After the COMBINE study 
ends, participants may no longer withdraw consent for the biosample repository, as there will no longer a 
way to link any individual with any stored specimen. 
2.5 
Privacy and security 
Local clinical sites will store patient information in a secure manner, and HIPAA privacy rules will be 
followed.   For purposes of this study, patients will be identified only by an assigned identification 
number and a randomly generated alphanumeric code.  The study database will be password protected, 
and clinical site personnel will be restricted from seeing data for patients from centers other than their 
own.  The study database will reside on a password-protected computer at the Data Coordinating Center 
(DCC).  No individual identifiers (patient name, SSN, or device serial number) will be stored. Data will 
be entered with strong encryption and a Thawte, Inc., system will be used for secure transmission of data 
from the clinical sites to the Data Coordinating Center. The DCC ensures accuracy and reliability of 
computer systems used for this study with detailed edit checks and tests of data interface screens, reports, 
and procedures before implementation.  Computer-generated, time-stamped audit trails are kept. The 
database is incrementally backed up daily, with full back ups performed weekly.  Backups are stored at a 
secure location separate from the site of the database server. 
In those instances where a patient document (such as a hospital discharge summary or death certificate) is 
sent to the DCC, the site study coordinator will de-identify this prior to providing it to the DCC.  The 
DCC will store these de-identified patient documents in locked file cabinets. 
Clinical site and DCC staff members will be required to change their passwords every 75 days, and staff 
who are no longer active in the study will be blocked from database access.  
3 
BASELINE PERIOD EVALUATION 
3.1 
Introduction 
Participants who successfully complete the screening visit and are deemed eligible will proceed to the 
Baseline Period.  The Baseline Period will consist of a 2-week run in period with 3 weekly visits (B0, B1 
and B2, Table 1).  
3.2 
Baseline collection of concurrent meds at study entry  
Participants will be asked to bring their medications, including all current prescription medications, over-
the-counter medicines, with them to the study visit.  Study staff will record all concomitant medications 
that the participant is taking.  
3.3 
Comorbidity assessment 
Study staff will record medical history, including history of tobacco and alcohol use. 

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3.4 
Description of run in  
The study will include a 2-week run-in, during which compliance with the two placebos and adherence to 
requirements for visits and procedures will be assessed.   Placebo treatment will consist of one 
nicotinamide 750 mg placebo daily and three lanthanum 500 mg placebos daily (one taken with each 
meal) reflecting similar dosing from the F0 to F1 period. During this run-in, 2 weekly visits will take 
place.   
The following adjustments in lanthanum carbonate placebo will be made during run-in for participants 
who eat fewer than 3 meals per day:  
 
Participants who eat only 2 meals a day and no snacks will take one 500 mg lanthanum carbonate 
placebo with each meal 
 
Participants who eat 2 meals a day and one snack will take one 500 mg lanthanum carbonate placebo 
with each meal and one with a snack 
For calculation of compliance, all participants will be assumed to be taking two lanthanum carbonate 
placebo per day. 
Patients will bring 24-hour urine collections to B1 and B2 visits.   Study staff will record the 24-hour 
urine volume and participants will be asked whether all urine was collected.  Aliquots of the 24-hour 
urine will be collected and submitted to the core lab.   
At each visit, participants will receive education from the trained coordinators regarding efforts to 
reducing dietary phosphate intake.  The information will include a) instructions on how to read food 
labels in order to avoid foods with phosphate additives23; b) advice to reduce serving sizes of animal 
protein; c) encouragement of consumption of vegetarian sources of protein instead of animal protein; d) 
advice to reduce consumption of dairy, and e) encouragement of consumption of egg whites instead of 
egg yolks.   
At each baseline study visit, blood samples will be collected. Whenever blood is drawn, time of day will 
be recorded. When two core lab measures of serum phosphate, FGF23 level, and mineral metabolites are 
obtained during the baseline period, the mean of these two will be used as the baseline values in the 
analyses. 
Height will be measured at screening or at the baseline 0 visit. 
Prior studies have shown that assessment of the effects of dietary phosphate restriction on serum 
phosphate levels were masked if serum phosphate measurements were done in the early morning.27 In 
contrast, assessments in the mid-afternoon allowed for detection a change in serum phosphate levels 
following interventions.27   Because of this, it is recommended that the trial’s two baseline serum 
collections are both conducted between noon and 6:00 pm.  It is also recommended that subsequent clinic 
appointments be held in the afternoon to maximize detection of the effect of the intervention on serum 
phosphate levels and minimize influence of circadian changes.  Ability to come in for afternoon 
appointments is not an absolute requirement for study participation.  Participants who conduct both of 
their baseline visits in the morning due to necessity will be categorized as morning participants.  Study 
coordinators will schedule their follow-up visits at about the same time as their baseline visits were held 
to minimize effects of circadian rhythm on longitudinal changes in phosphate and FGF23. 
After participants meet all inclusion criteria and screening requirements, pre-randomization cardiac and 
BOLD renal MRI scans will be obtained.  These imaging studies could occur anytime between Baseline 
Visit 0 (B0) and prior to Baseline Visit 2 (B2).  The optimal timing for the baseline MRI scans is prior to 
B2, but the studies may occur up to two weeks after B2.  Participants who have a contraindication to the 
MRI (i.e. pacemaker) will not undergo MRI studies but will continue to undergo all other study 
procedures.  

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Each participating clinical center will be provided with a detailed imaging protocol and will be required to 
submit qualifying studies for certification by the MRI Cores prior to enrolling participants.  All cardiac 
and BOLD renal MRI results will be captured according to pre-specified protocols, sent to and stored at 
the Cardiac MRI Core at Northwestern University.  All cardiac MRI Core results will be read by the 
Cardiac MRI Core at Northwestern University.  All BOLD renal MRI results will read by the Renal MRI 
Core at NorthShore.  
3.5 
Compliance assessment 
Compliance with study procedures will be defined as attendance at Baseline visits 0 and 1 and pill count 
results showing > 80% adherence to baseline placebo medications during Baseline, as assessed at least 
once (either B1 or B2).   
3.6 
Maximum time allowed in baseline 
The maximum time between the screening and the B0 visits will be 1 month.  Baseline officially begins 
when the patient is given his or her study medications at the B0 visit.  It is expected that patients will be 
randomized within 3 weeks of the B0 visit.  If necessary, patients can be randomized up to 6 weeks (42 
days) after B0.  If more than 42 days pass, the patient is excluded but may restart baseline, repeating 
screening and baseline measures to assure that the participant still meets all inclusion and exclusion 
criteria.. 
3.7 
Collecting reasons for baseline drop out  
Study staff will document reasons for baseline exclusion or drop out.  
3.8 
Assessment of readiness for randomization  
Study staff will run the “Ready to Randomize Report” checklist for each participant to check that the 
participant meets criteria. 
4 
RANDOMIZATION AND RECRUITMENT MONITORING  
4.1 
Randomization in an intent-to-treat clinical trial 
The study site Principal Investigator or a designated site investigator will review the screening and 
baseline materials and sign off on randomization before randomization is completed.   Randomization 
marks the participant's official and irrevocable entry into the Follow-up period. Once a participant has 
been randomized, efforts will be made to conduct all evaluations irrespective of whether the participant 
starts the study treatment regimen, how long the participant continues on the study treatment regimen or 
not, and how well the participant complies with the study treatment regimen.  
Routine data collection will end when a patient begins dialysis, dies, is deemed lost to follow-up or 
withdraws consent. Otherwise, all efforts will be made to continue data collection through the end of 
follow-up even if a participant’s medication never begins, the participant is not compliant, or the 
participant must stop randomized medications for any reason.  The primary analysis of outcome will be 
analyzed as intent-to-treat, by randomized treatment group. 
4.2 
Logistics of randomization 
The DCC will prepare randomization schedules prior to the start of recruitment. Randomization will be 
stratified by participating site. Randomly permuted blocks of random sizes will be used to help balance 
numbers of participants assigned to each treatment regimen.  This method guarantees that at no time 
during randomization will the number of participants in any arm be grossly imbalanced and ensures that 
the sites will be unable to predict assignments of future patients based on knowledge of assignments of 
past patients. All randomization schedules will remain confidential and known only by members of the 
DCC staff. 
Baseline data that have been categorized as essential must be in the database and support eligibility in 
order for a subject to be randomized. The study coordinator can run the Ready to Randomize Report at 
any time during baseline to check the patient’s status with respect to meeting eligibility requirements. 

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When the site investigator signs off that a participant should be randomized and the participant’s Ready to 
Randomize Report shows eligibility criteria have been met, the Study Coordinator will use his or her 
current database password to access an on-line interactive randomization program. The program will 
verify eligibility and Baseline criteria to confirm that the participant is eligible and ready to be 
randomized and a randomized treatment assignment will be recorded for that participant, based upon his 
or her stratum. The study is blinded, so treatment assignment will not be displayed. The computer will 
display the participant’s initial bottle numbers for the Nicotinamide/Placebo and for the 
Lanthanum/Placebo.  Confirmation of randomization will be displayed on the screen and emailed to the 
Participating Clinical Center.  The treatment assignment will be used to assign the patient with his or her 
coded packages of study drug.   
4.3 
How recruitment will be monitored 
The DCC will email study-wide weekly recruitment reports showing study-wide weekly and cumulative 
enrollment in baseline and randomization. The reports will also include each site’s current baseline goal, 
achievement of baseline goal, randomization goal, and achievement of randomization goal.  Clinical site 
investigators will meet regularly with their study teams to discuss progress on weekly goals, identify 
barriers and problems, and revise recruitment plans as necessary. The Investigators from multiple sites 
will meet by conference call at regular scheduled intervals to review each site’s recruitment progress, 
share problems and successes, and revise recruitment plans as necessary. 
5 
TREATMENT ARMS 
5.1 
Initiation of treatment 
Participants meeting eligibility criteria, having given their informed consent and successfully collected 
required run in data and completed the run-in period will be eligible for randomization.  Baseline cardiac 
and BOLD renal MRI studies should preferably take place prior to randomization. However, the studies 
may occur up to two weeks after B2.  As soon as Baseline data, including cardiac and BOLD renal MRI, 
if available, have been collected and required data show that the patient has met criteria for eligibility for 
randomization, the study coordinator will randomize the patient.  The patient should receive the first 
bottles of blinded study medication as soon as possible post-randomization. 
Participants will be randomized to one of the following 4 groups:  
• 
Lanthanum carbonate + nicotinamide  
• 
Lanthanum carbonate + nicotinamide placebo 
• 
Lanthanum carbonate placebo + nicotinamide  
• 
Lanthanum carbonate placebo + nicotinamide placebo 
 
During the first month following randomization (F0 to F1), randomized treatments will be started at lower 
doses. All participants will take one 750-mg nicotinamide or matched placebo daily.   
Lanthanum carbonate or its placebo will be prescribed as follows: 
Participants who eat 3 meals a day will take one 500 mg lanthanum carbonate or matched placebo with 
each meal (1500 mg). 
Those who eat fewer than 3 meals a day will receive adjusted doses: 
 
Participants who eat 2 meals a day with no snacks will take one 500 mg lanthanum carbonate or 
matched placebo with each meal (1000 mg). 
 
Participants who eat 2 meals a day and one or more snacks will take one 500 mg lanthanum carbonate 
or matched placebo with each meal and one 500 mg lanthanum carbonate or matched placebo with a 
snack (1500 mg). 
For the remainder of the study (F1 through F12), randomized treatments will be taken at full doses.  All 
participants will take nicotinamide 750 mg or matched placebo twice daily (1500 mg). 

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Participants who eat 3 meals a day will take two 500-mg lanthanum carbonate or matched placebo with 
each meal (3000 mg). 
Those who eat fewer than 3 meals a day will receive adjusted doses: 
 
Participants who eat 2 meals a day with no snacks will take two 500-mg lanthanum carbonate or 
matched placebo with each meal (2000 mg). 
 
Participants who eat 2 meals a day and one snack will take two 500-mg lanthanum carbonate or 
matched placebo with each meal and one 500 mg lanthanum carbonate or matched placebo with the 
snack (2500 mg). 
 
Participants who eat 2 meals a day and two or more snacks will take two 500-mg lanthanum 
carbonate or matched placebo with each meal and one 500-mg lanthanum carbonate or matched 
placebo with 2 snacks (3000 mg). 
5.2 
Dose adjustments and treatment stops related to serum phosphate levels 
5.2.1 Dose adjustment due to hypophosphatemia  
If a study participant has a core lab serum phosphate level lower than 2.8 mg/dl at any visit, an extra visit 
should be held as soon as possible so the serum phosphate test can be repeated.  This repeat lab will be the 
"action lab" for dose adjustments, regardless of the core lab serum phosphate level.  The local action lab 
should be obtained as soon as possible, but must be obtained within 15 days of the core lab blood draw.  
In the event that the local action lab cannot be obtained, or is not available within 15 days, then the 
available core lab serum phosphate level becomes the action lab for dose adjustments. 
If the action lab test demonstrates a serum phosphate level of 2.8 mg/dL or higher, the participant should 
continue on full dose medications until the next protocol visit.  If the serum phosphate level on the action 
lab test is between 1.5 and 2.7mg/L, both study medications should be prescribed at half dose until the 
next protocol visit.  If the serum phosphate level is ≤ 1.4 mg/dL on the action lab test, both study 
medications should be stopped until the next protocol visit.   
Participants with an action lab test of 1.5 md/dL or higher can enter into the same algorithm summarized 
above at any subsequent protocol visit.  In contrast, participants with an action lab test of 1.4 mg/dL or 
lower require special consideration through the remainder of the trial.  In such an individual, if a core lab 
serum phosphate is 2.8 mg/dL or higher at a subsequent protocol visit, both study medications should be 
restarted at half dose, and the doses of these medications should not be titrated above half dose throughout 
the remainder of the trial.  If the serum phosphate level on a subsequent protocol visit core lab is 2.7 
mg/dL or lower, the participant should return for a local action lab draw within 15 days, as summarized 
above.  If the action lab is 2.7 mg/dL or lower, the participant should remain off both study medications 
until such time as their serum phosphate is 2.8 mg/dL or higher at a subsequent core lab measurement.  
Last, if a participant has previously had an action lab test ≤ 1.4 mg/dL resulting in the need to hold their 
study medications at any point during the trial, and has a subsequent action lab test ≤ 1.4 mg/dL again at 
any point during the remainder of the trial, this individual should be maintained off both study 
medications for the remainder of the trial.   In such an individual, even if subsequent core or local action 
lab tests return to levels of 2.8 mg/dL at future visits, the study medications should not be restarted.  
Additional recommendations for managing COMBINE participants with hypophosphatemia are included 
in the Manual of Operations (MOP). 
5.2.2 Treatment safety medication stop due to hyperphosphatemia 
If a study participant has a central serum phosphate level of 5.9 or greater, an extra visit should be held as 
soon as possible so the test can be repeated locally.  If the local test confirms a serum phosphate level 
over 5.9 mg/dl, this is a treatment safety medication stop for both study medications.  All visits and 
measurements will continue.   If the patient has a primary nephrologist or primary care physician, it is 
recommended that he or she be notified about the hyperphosphatemia and management will be deferred to 
these providers.   

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5.2.3 Dose adjustments due to intolerable GI or other side effects 
Calcium carbonate tablets such as Tums, may be taken for indigestion if used once per day or less.  
However, patients who report using Tums (calcium carbonate) often will be encouraged to try over-the 
counter Pepcid (famotidine), Tagamet (cimetidine), or Zantac (ranitidine). 
If a participant develops GI or other side effects that he or she considers to be intolerable or that are 
considered intolerable by the site investigators, dose adjustment will be at the discretion of the site 
investigator.  Appropriate actions may include reduction of the dose of lanthanum carbonate or its placebo 
and/or reduction of the dose of nicotinamide or its placebo, as described in detail in the MOP. 
5.3 
Management of dose adjustments of study drugs in the presence of other medications 
Use of any 1,25(OH)2 vitamin D preparations and active vitamin D analogues is strongly discouraged 
during the study.  Use of 1,25(OH)2 vitamin D and/or active vitamin D analogues   will be recorded. 
5.4 
Supply of treatment  
The COMBINE Study Drug Distribution Center will send COMBINE participating sites kit boxes of 
either bottles of blinded lanthanum and lanthanum placebo or bottles of nicotinamide and nicotinamide 
placebo.    
 
5.5 
Resupply of treatment 
Treatment bottles will be sufficient to supply 30 days of study agents plus 10 days of extra medication to 
account for variability in dates of scheduling for follow-up visits (80 tablets per bottle for nicotinamide 
and its placebo, and 240 tablets per bottle for lanthanum carbonate and its placebo).  For follow-up visits 
separated by multiple months, participants will receive the appropriate number of treatment kits to 
provide sufficient drug/placebo (e.g., 3 kits for a 3 month interval between visits).  Dose reductions 
procedures are described in detail in the MOP.  
5.6 
Maintaining blinding  
Throughout the Follow-up Period, all efforts will be made to keep study coordinators, investigators and 
participants blinded to treatment group.  Coordinator and investigator blinding will be assessed quarterly; 
patient blinding will be assessed at the end of the study. 
5.7 
Unblinding 
In the situations previously described, a participant will stop his or her blinded nicotinamide and 
lanthanum carbonate.  In this situation where appropriate clinical management of the patient is dependent 
on knowledge of whether the patient had been taking active nicotinamide or active lanthanum carbonate, 
the site investigator will explain the necessity to the study Executive Committee, and the Executive 
Committee will unblind the site physician to the necessary arm.   
6 
FOLLOW-UP PERIOD EVALUATION   
6.1 
Follow-up visit schedule and schedule of tests done during follow-up  
6.1.1 
Overview 
In person follow-up visits will occur monthly for first 3 months after Randomization and every 3 months 
from month 3 until month 9.  There will be a two month interval between month 9 and 11, and finally a 1 
month interval between month 11 and 12 (Table 1).  Additional visits will be held as needed at the 
discretion of the site investigator and study team members.  All visits will be documented in the study 
database. 
6.1.2 
Description of procedures during in-person visits 
At in-person visits, patient compliance to study drugs will be assessed either by questionnaire or pill 
count depending upon the visit (Table 1).  The study coordinator will reinforce instructions on dietary 
phosphate restriction.  Concomitant medication therapy will be reviewed and updated at baseline, F3 and 
every 3 months thereafter.  Information on adverse events (serious and non-serious) will be collected.  
The schedule of laboratory tests to be obtained during the in-person visits is listed in Table 1.  Additional 
blood samples will be collected and stored for future measurements. A GI symptoms form will be 

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completed by questionnaire at each protocol visit.  Blood pressure will be measured by trained personnel 
at all follow-up visits.  Twenty-four hour urine specimens will be collected at some visits (Table 1) and 
will be measured phosphate, calcium, urea, and creatinine.  The 24 hour urine phosphate will be used as 
an indicator of dietary phosphate absorption and the 24 hour urea will be used as an indicator of dietary 
protein intake. 
At each follow-up visits, participants will be counseled that they must not take any phosphate binders or 
multivitamins containing vitamin B3 in the form of niacin or nicotinamide in quantities greater than 100 
mg/day.  If a participant is taking a standard multi-vitamin tablet with < 100 mg/day of nicotinamide, the 
dose of the multivitamin may not be changed during the study period. 
Between F11 and F12 or upon withdrawal from study (for dialysis initiation or preemptive transplantation), 
participants will undergo cardiac and BOLD renal MRI. The cardiac and BOLD renal MRI may occur 
anytime between F11 and 2 weeks after F12 or at the time of early discontinuation prior to initiation of 
renal replacement therapy.  If a participant withdraws from the study within 6 weeks of their baseline 
MRI studies, discontinuation MRI studies will not be performed.  MRIs should not be obtained in 
participants who have started dialysis or have been transplanted.  Participants who have a 
contraindication to the MRI (i.e. pacemaker) will not undergo MRI studies but will continue to undergo 
all other study procedures.     
6.2 
Monitoring compliance to treatment   
In order to document compliance with the treatment regimen, participants will be instructed to return all 
drug containers (even if empty) to study staff at all visits.  Pill counts will be done at B1, B2, F1, F2, F3, 
and F12. To decrease the chance of a participant forgetting to bring pills at pill-count visits, participants 
will be asked to bring remaining pills and empty containers to each visit during the study. 
Study staff will record the number of each type of pill returned, and the study database will calculate 
percent of medications taken. Participants will also be asked a semi-quantitative question for each 
medication: whether or not they are taking each medication regularly (in every intended instance or 
almost every intended instance), irregularly, or not at all.  
Compliance with each study drugs will be defined as use of ≥80% of expected drugs based on pill count 
data. Data from the semi-quantitative questions will be used to enhance adherence and to provide a 
secondary measure of adherence. 
6.3 
Procedures for patients who start dialysis or undergo kidney transplantation  
Participants will be withdrawn from the study if they initiate renal replacement therapy or undergo kidney 
transplantation.  MRIs should be obtained in these participants prior to their first renal replacement 
therapy. 
6.4 
Procedures for patients who become pregnant 
Participants will be withdrawn from the study if they become pregnant. 
 
7 
CHARACTERIZATION OF THE MEASUREMENTS AND PROCEDURES DURING SCREENING, 
BASELINE, AND FOLLOW-UP AND METHODS OF MEASUREMENT TO BE USED 
7.1 
GFR Calculation 
GFR will be estimated from Core Biochemistry Lab serum creatinine values using the CKD-
Epidemiology Collaboration equation.27 
 
 

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7.2 
List of laboratory measurements 
The following lab tests will be performed at the COMBINE Primary Core Lab at Spectra: 
 
Serum Tests 
sodium, potassium, chloride, bicarbonate, urea nitrogen, creatinine, glucose, calcium, phosphate, 
aspartate aminotransferase, alanine aminotransferase, total bilirubin, alkaline phosphatase, albumin, 
creatine kinase, uric acid, and PTH 
Whole Blood Tests 
hemoglobin A1c, white blood cell count, hemoglobin, hematocrit, and platelets. 
Urine Tests 
calcium, creatinine, phosphorus, and urea nitrogen 
The following lab tests will be performed at a central FGF23 laboratory: 
 
Serum Tests 
FGF23  
Levels of calcitriol, klotho, P1NP, Trap-5b, BNP, troponin T, cholesterol, ADMA, CRP and IL-6 
will also be measured at the central FGF23 laboratory (performed in batches, in either plasma or 
serum). 
8 
ADVERSE EVENTS, ADVERSE EVENT REPORTING 
8.1 
Introduction 
Adverse events include any untoward medical occurrence in a participant administered the study drugs 
and which does not necessarily have a causal relationship with the study drugs.  AEs can include 
abnormal laboratory findings, symptoms, or disease temporally associated with the use of study drugs, 
whether or not the event is considered causally related to the use of the study drugs.  AEs can result from 
use of the study drugs as stipulated in the protocol, and from accidental or intentional overdose, drug 
abuse, or drug discontinuation.  An AE may meet the criteria for a serious adverse event (SAE). 
8.2 
Expected Study Adverse Events 
8.2.1 
Types of AEs that may be treatment or procedure side effects 
Lanthanum carbonate may lower serum phosphate levels and is associated with gastrointestinal side 
effects including nausea, vomiting, constipation and diarrhea.   
Nicotinamide may lower serum phosphate levels and may be associated with other laboratory 
abnormalities including thrombocytopenia, abnormalities in serum liver function tests and CK.  
Gastrointestinal side effects, such as diarrhea and heartburn may also occur.  
The following laboratory results will be flagged as expected study adverse events in this trial: 
 
Hypophosphatemia:  Serum phosphate level <1.5 mg/dl 
 
Hyperphosphatemia: Serum phosphate >5.9 mg/dl  
 
Thrombocytopenia: Platelet count <100,000 
 
Liver function test abnormalities:  AST, ALT, total bilirubin, alkaline phosphatase > 4 times 
the upper limit of normal  
Elevated Creatine Kinase: Creatinine kinase > 4 times upper limit of normal.  
 
The following symptoms will be flagged as expected study adverse events in this trial.  
 
Bruising   
 
Bleeding   
 
Severe diarrhea 
 
Severe nausea 

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 
Flushing  
 
Hives 
 
Heartburn.  
The following are expected adverse events related to the MRI scans: 
 
Risks related to undetected metal 
 
Distress from incidental findings that may necessitate additional work up  
 
Risks from furosemide administration in participants with unknown or unrecorded allergy 
to furosemide.  
8.2.2 
How AEs will be reported 
Laboratory tests will be performed periodically to monitor safety, as indicated in Table 1.  Laboratory 
measurement based AEs will be detected.  Other adverse effects will be assessed at each follow-up visit 
during symptom questionnaire discussions.  Adverse events related to MRI scans will be recorded after 
each MRI visit and summary reports will be made available to the DSMB.  
8.2.3 
Follow-up of AEs 
Hypo- and hyperphosphatemia will be treated as described in the MOP. 
GI side effects will be treated as described in the MOP. 
Some AEs, if confirmed, lead to discontinuation of one or both blinded study medications.  Details are 
provided in Protocol Section 9.1 
8.3 
SAE, Hospitalization, and Death reporting 
Standard SAEs listed as follows will be reported in detail and reviewed by the Event Review Committee. 
 
Death 
 
Life-threatening event   
 
Hospitalization 
 
Prolongation of hospitalization  
 
Congenital anomaly   
 
Persistent or significant disability/incapacity 
 
Important medical event requiring medical or surgical intervention to prevent serious outcome 
 
Spontaneous abortion 
8.3.1 
Local Categorization of SAEs as Unanticipated, Related 
When an SAE is documented, the local Clinical Center’s Investigator will report on the SAE Detail Form 
whether the SAE was unanticipated.  An unanticipated SAE, as defined by DHHS 45 CFR part 46, meets 
following three criteria: 1) unexpected, in terms of nature, severity, or frequency, given (a) the research 
procedures that are described in the protocol-related documents, such as the IRB-approved research 
protocol and informed consent document; and (b) the characteristics of the study population; 2) related or 
possibly related to participation in the research (in this guidance document, possibly related means there 
is a reasonable possibility that the incident, experience, or outcome may have been caused by the 
procedures involved in the research);  and 3) suggests that the research places participants or others at a 
greater risk of harm (including physical, psychological, economic, or social harm) than was previously 
known or recognized will determine use the following definitions to assess the relationship of the adverse 
event to the use of study treatment.   
The site investigator will also classify the SAE as not related, probably not related, possibly related, 
probably related, or related to study procedures and treatments. 
8.3.2 
Event Committee Review of SAEs 
The COMBINE Study Event Committee will review the first 10 SAEs occurring at each site in the 
COMBINE Study.  After that, the Event Committee will review all deaths, all SAEs that the site 
investigators categorized as possibly related, probably related, or related and a 10% QC subset of the 

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SAEs that the site investigator categorized as unrelated.  The primary Event Committee reviewer for each 
reviewed SAE will be chosen from members of the Event Committee who are from sites other than the 
site where the SAE occurred. When SAE data are presented to the study’s DSMB for safety review, both 
the local site and Event Committee categorization will be presented. 
9 
STOPPING RANDOMIZED TREATMENT   
9.1 
Stopping randomized treatment for Adverse Events  
Participants will stop treatment with both nicotinamide and lanthanum carbonate due to either hypo- or 
hyperphosphatemia. Data collection will continue as usual. 
Participants will stop treatment with nicotinamide, but continue on the blinded lanthanum carbonate, if 
the following occur: 
 
On two consecutive measures, participant is found to have liver function test (AST, ALT, total 
bilirubin, or alkaline phosphatase) or CK levels > 4 times the upper limit of normal without other 
identifiable cause. 
 
On two consecutive measures, participant is found to have a platelet count <100,000 with clinical 
signs of platelet dysfunction (bruising or bleeding noted at a study visit and documented on the 
symptom form) or <75,000 without clinical signs 
9.2 
Stopping randomized treatment for Adverse Events  
Participants will stop treatment with nicotinamide and/or lanthanum carbonate, but data collection will 
continue as usual, if the site investigator and the Event Committee agree that an SAE was possibly, 
probably, or definitely related to treatment and that it is unsafe for the patient to continue on the specified 
treatment (nicotinamide and/or lanthanum carbonate). 
Procedures for dose adjustment in the case of gastrointestinal side effects are described in the MOP. 
9.3 
Discontinuation of study medications due to patient preference/non-compliance  
Participants who wish to discontinue study medications will be encouraged by the Site PI and study 
coordinator to continue with visits, lab tests, and data collection so data will be available for intent to treat 
analysis of the trial. The site PI will encourage passive data collection such as hospitalization 
documentation for participants who no longer want to attend visits.  
9.4 
The role of Study Committees in review of lab data and adverse events  
Lab data from the Core Lab will be reported to each site investigator and the site team as soon as the 
results are available to the study database.  The Quality Control Committee will review lab data.  The 
Event Review committee will review SAEs and any events that the clinical centers categorize as requiring 
treatment discontinuation for safety reasons. 
10 
DSMB 
NIDDK will name a DSMB for this clinical trial.  The DSMB will include clinicians, statisticians, and 
other experts as needed, and will include experts on research and clinical expertise in CKD-mineral bone 
disorders.   Acting as a protocol review committee, the DSMB will review and approve the study 
protocol.   As the study progresses, NIDDK will schedule routine meetings and conference calls of the 
DSMB.  At these meetings, the DSMB will review reports of study progress in the areas of recruitment, 
retention, quality control, and safety related to study medications and to MRI scans.  The DSMB can ask 
for additional reports or additional meetings at their discretion.   
11 
ANALYSIS PLAN 
11.1 Primary analysis 
Specific Aim 1 of this clinical trial will evaluate changes over time in absolute levels of serum phosphate 
and FGF23 levels, with each active treatment group compared to the double placebo group.  Based on 
prior data, both serum phosphate and FGF23 levels are expected to decline from baseline within the first 
three months and then to be stable thereafter.   

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Because the distribution of FGF23 is expected to be skewed, FGF23 values will be log transformed. A 
piecewise mixed-model, repeated-measures analysis will be performed to assess separately changes in 
two primary endpoints within the first 3 months and in the period thereafter (months 3 – 12).  The 
analysis will be stratified by clinical center. Covariates included in the model will include baseline eGFR 
and gender. 
When two measures of serum phosphate and FGF 23 are available, the average of these two baseline 
values of serum phosphate (for models evaluating phosphate as the outcome variable) and FGF23 (for 
models evaluating FGF23 as the outcome variable) levels will be used as the baseline value for analyses 
of treatment comparison (Table 1).    
Specific Aim 2 will address tolerability and safety evaluations in the intention to treat population.   
Tolerability: The primary measure of tolerability will be the percentage of persons who come off study 
drug across treatment.  The percentages will be summarized by treatment group and differences will be 
evaluated using the Fisher's exact test.  Compliance by pill count and questionnaire will be evaluated as 
secondary outcomes. 
Safety: The number and percentage of the participants who report at least one adverse event will be 
summarized by treatment group and overall.  The treatment group difference in the percentages will be 
evaluated using Fisher's exact test. Adverse events will also be summarized descriptively with counts and 
percentages. 
11.2 Secondary Analyses 
A secondary objective is to determine whether or not combined treatment with lanthanum carbonate and 
nicotinamide lowers serum phosphate or FGF23 more so than either nicotinamide alone or lanthanum 
alone.   If no significant interaction between nicotinamide and lanthanum carbonate is seen, the main 
effects of each active treatment as in a factorial design study will be evaluated.  As in analysis for the 
primary outcome, we will stratify for clinical center and use averages of baseline serum phosphate (in 
models evaluating phosphate as the outcome variable) and averages of baseline FGF23 (for models 
evaluating FGF23 as the outcome variables) as the baseline values in the analyses.   Models will be 
adjusted for eGFR and gender, as in the primary analysis. 
To address expected cross-over from on-protocol to off-protocol management due to hypo- and 
hyperphosphatemia and off-protocol binder use, “as-treated” exploratory analyses will be included.  
For analyses of the secondary objectives, linear mixed models to analyze effects of all active-treatment 
groups combined vs. placebo group will be used.  In pre-specified secondary analyses, differences 
between the four treatment groups, perform as treated analyses and test the association between the 
magnitude of reduction in phosphate and FGF23 and changes in the secondary objective end points will 
be used.   
11.3 Analyses of other follow-up data  
Mixed-model, repeated-measures analyses will be used for comparisons of changes of PTH, calcium, 
eGFR, and urine ACR.  When analyses of 24-hour urine are performed, the only collections that will be 
used will be those in which the measured 24-hour urine creatinine excretion is within 30% of estimated 
creatinine excretion using the CKD-EPI creatinine excretion rate estimation equation.24 
11.4 Safety analyses 
Standard analyses will be used for safety evaluations conducted in the intention-to-treat population. As-
treated analyses will be performed if there are treatment crossovers due to non-compliance or if study 
medications are stopped due to adverse or other events. 

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11.5 Planned analyses of feasibility/logistics including rates of missing data, missing forms, 
 missing visits, and of non-compliance. 
This 12-month study will provide important feasibility data on long-term tolerability, safety, and 
adherence.  Standard analyses of recruitment, retention, and compliance will be used for feasibility 
evaluations   
11.6 What will it take to say that this pilot study is feasible?  
The COMBINE Study will be judged to be feasible if 1) any of the primary efficacy analyses on serum 
phosphorus or FGF23 is significant at the .05/6 level and 2) the intervention(s) associated with the 
outcome(s) met the following criterion for compliance and tolerability: The majority of randomized 
patients are able to complete 12 months of follow-up without having to discontinue either the lanthanum 
arm or the nicotinamide arm. 
11.7 Test run of the analysis plan for the full scale study 
Although this pilot study is not powered to detect changes in CKD progression, longitudinal data on 
serum creatinine and spot urinary albumin-creatinine ratio (UACR) will be considered.  At the end of the 
study, changes in eGFR over time and rates of ESRD, CVD events, fractures and death by randomized 
treatment group will be done. 
12 
PLANS FOR THE STUDY DESIGN OF THE FULL SCALE TRIAL 
12.1 Current Plans for Primary Outcome of the Full Scale Trial 
Our long-term goal is to conduct a placebo-controlled, randomized trial to target hard clinical endpoints 
hypothesized as down-stream consequences of phosphate and FGF23 excess.  Hard end-points will 
include a combination (to be determined) of ESRD, CVD events, fractures and death. 
13 
ACKNOWLEDGEMENTS 
If using CTSA/GCRCs, they will be acknowledged here by grant number.   
 
Nicotinamide and Nicotinamide placebo were donated by Endurance.  Lanthanum Carbonate and 
Lanthanum Carbonate placebo were donated by Shire. 
 
14 
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