An Open-label, Phase 2a Trial to Evaluate the Effect of Escalating Doses of IW-1973 on Tolerability, Endothelial Function, and Hemodynamics in Patients With Stable Type 2 Diabetes and Hypertension
Phase: PHASE2
Conditions: Diabetes Mellitus, Type 2, Hypertension
Sponsor: Cyclerion Therapeutics



IW-1973 Tablet 
 
Ironwood Pharmaceuticals, Inc. 
Clinical Trial Protocol: C1973-201-P-03 
 
09 January 2017 
 
Confidential 
Page 2 of 74 
STUDY IDENTIFICATION 
A summary of key study participants is provided in Table 1. All study contact details will be 
provided prior to the Site Initiation Visit. 
Table 1. 
Key Study Participants 
Role 
Contact Information 
Principal Investigator and Study Center: 
 
ICON Early Phase Services, LLC  
8307 Gault Lane  
San Antonio, TX 78209 
 
 
Ironwood Contact: 
  
Ironwood Pharmaceuticals, Inc. 
301 Binney Street 
Cambridge, MA  02142 
(
 
 
Medical Monitor: 
 
Ironwood Pharmaceuticals, Inc 
301 Binney Street 
Cambridge, MA  02142 
  
 
Safety Officer: 
 
Ironwood Pharmaceuticals, Inc 
301 Binney Street 
Cambridge, MA  02142 
(
 
 
Serious Adverse Event (SAE) E-mail: 
 
Dedicated SAE Facsimile Number: 
 
 

IW-1973 Tablet 
 
Ironwood Pharmaceuticals, Inc. 
Clinical Trial Protocol: C1973-201-P-03 
 
09 January 2017 
 
Confidential 
Page 3 of 74 
SYNOPSIS 
Sponsor 
Ironwood Pharmaceuticals, Inc. 
Name of Finished Product 
IW-1973 Tablet 
Name of Active Ingredient 
IW-1973 
Study Title 
An Open-label, Phase 2a Trial to Evaluate the Effect of Escalating Doses of IW-1973 on 
Tolerability, Endothelial Function, and Hemodynamics in Patients with Stable Type 2 
Diabetes and Hypertension 
Study Number 
C1973-201 
Study Phase: 2a 
Objectives  
In adult patients (N = 12) with stable type 2 diabetes mellitus and controlled hypertension:  
• To evaluate the safety and tolerability of escalating doses of IW-1973  
• To evaluate the impact of escalating doses of IW-1973 on 
- 
endothelial function using EndoPAT™ (Itamar Medical; Caesarea, Israel) to measure 
fingertip small vessel pulse volume 
- 
blood pressure (BP) and heart rate 
Study Design 
This open-label, single-center trial will enroll 12 patients (at least 4 men and 4 women) to 
receive once-daily study drug for 6, sequential, 3-day dosing cycles (18 total days) starting 
with placebo (baseline) for 3 days and then progressing to 5 escalating dose levels of IW-1973 
(10, 20, 30, 40, and 50 mg) for 3 days each (see Study Schematic). 
Study Population  
The study will enroll 12 patients with  
• Type 2 diabetes with a hemoglobin A1c (HbA1c) level of ≤ 10.5% and a fasting 
(≥ 8 hours) blood glucose level of ≤ 240 mg/dl on a regimen of ≥ 1 medication for 
glycemic control with no change in medication for at least 12 weeks before Check-in and 
on a stable regimen (ie, same drug and same dose) for ≥ 28 days before Check-in  
• Hypertension with systolic BP of 120 to 160 mm Hg and diastolic BP of 70 to 100 mm Hg 
while on a stable regimen of ≥ 1 medication for at least 30 days before the Screening Visit 

IW-1973 Tablet 
 
Ironwood Pharmaceuticals, Inc. 
Clinical Trial Protocol: C1973-201-P-03 
 
09 January 2017 
 
Confidential 
Page 5 of 74 
before and after a 0.4 mg dose of sublingual nitroglycerin. Patients will remain in the Study 
Center for ≥ 2 hours until BP and pulse return to predose or acceptable, safe levels. Patients 
will return to the Study Center 28 (± 3) days after the final dose of study drug (Day 46) for the 
End of Trial Visit for final safety and PK assessments (see Schedule of Events). 
Patients who prematurely discontinue dosing will remain in the clinic for at least 24 hours 
after their final dose of study drug and will complete all Discharge day assessments. In 
addition, these patients will return to the Study Center for their Follow-up and End of Trial 
Visits 14 (± 2) and 28 (± 3) days, respectively, after their final dose of study drug. 
Study Drug Administration 
Patients will receive orally administered study drug at approximately the same time 
(± 15 minutes) every day in the morning (8 to 10AM), after an overnight fast of at least 
8 hours. Patients may take multiple tablets together. Permitted concomitant medications that 
the patient may be taking in the morning for diabetes and hypertension, or any other allowed 
concomitant conditions, should be taken at the same time as study drug. Breakfast should 
begin within 30 minutes after dosing.  
Stopping Criteria 
All dosing will be stopped if the Sponsor and Investigator determine that any of the following 
have occurred: 
• Drug-related SAEs in 2 or more patients (per causality and SAE definitions in the 
protocol)  
• An overall pattern of clinically significant AEs or an overall pattern of patient tolerability 
issues, which may appear minor in terms of an individual event but, in the opinion of the 
Sponsor or Investigator, collectively represents a safety concern 
Note: Safety and tolerability will be assessed daily and dosing may be discontinued or dose 
escalation may be cancelled on an individual patient basis. Patients who discontinue dosing or 
do not escalate will remain in the clinic for at least 24 hours after their final dose of study drug 
and will complete all Discharge day assessments. In addition, these patients will return to the 
Study Center for their Follow up and End of Trial Visits 14 (± 2) and 28 (± 3) days, 
respectively, after their final dose of study drug. 
Planned Number of Patients:   
Twelve patients may receive study drug in this trial. Additional patients (approximately 2 to 6) 
may be checked into the Study Center on Day -1 as back-ups. If the back-up patients are not 
needed, they will be discharged from the Study Center on Day -1 or Day 1. Patients 
withdrawing from the study after dosing will not be replaced. 
Duration of Treatment  
Patients will receive once-daily study drug for 18 days:  placebo for 3 days and escalating 
doses of IW-1973 for 15 days. Patients will be in clinic for 20 days, from Check in on Day -1 
to Discharge on Day 19. Total patient participation will be 45 to 77 days including Screening, 
Clinic, and Follow-up Periods. 

IW-1973 Tablet 
 
Ironwood Pharmaceuticals, Inc. 
Clinical Trial Protocol: C1973-201-P-03 
 
09 January 2017 
 
Confidential 
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Pharmacokinetics  
Blood samples will be collected according the Schedule of Events and the following PK 
parameters will be calculated, when possible: 
• AUCtau:  Area under the plasma concentration time curve during a dosing interval (tau) 
• Cmax:  Maximum observed plasma concentration, occurring at Tmax 
• Ctrough:  Trough plasma concentration observed at the end of a dosing interval (collected 
before the next administration) 
• t1/2:  Apparent terminal phase half-life 
• Tmax:  Time of maximum observed plasma concentration 
Safety  
Physical examination findings, vital sign parameters, 12-lead ECG results, clinical laboratory 
results (ie, clinical chemistry, hematology, coagulation, urinalysis, HbA1c, fasting glucose, 
and serum insulin), and patient- and Investigator-reported AEs will be evaluated. 
Statistical Methods:  
Sample Size Determination 
The sample size in this trial was determined outside of statistical considerations. A sample size 
of 12 patients is considered sufficient and is based on precedent set by prior studies of similar 
nature and design, as well as a review of published literature regarding the assessment of 
endothelial functioning by the EndoPAT technology.  
Analysis Populations: 
All patients who receive at least 1 dose of study drug will be included in the Safety 
Population. 
All patients who receive at least 1 dose of study drug and have at least 1 postdose PK 
parameter assessment will be included in the PK Population. 
All patients who receive at least 1 dose of study drug and have at least 1 postdose PD 
assessment will be included in the PD Population. 
Statistical Analysis 
Descriptive statistics (n, mean, standard deviation, minimum, median, interquartile range, and 
maximum) will be calculated to summarize continuous variables. Frequency and percent of 
patients in each category will be calculated to summarize categorical variables. 
Pharmacodynamic Analyses 
Summary statistics will be provided by treatment for RHI (from EndoPAT); supine, standing, 
and ambulatory BP and pulse rate values; and platelet function testing (from PFA-100). 
Changes from baseline (placebo cycle) in these variables will be compared across dose levels. 

IW-1973 Tablet 
 
Ironwood Pharmaceuticals, Inc. 
Clinical Trial Protocol: C1973-201-P-03 
 
09 January 2017 
 
Confidential 
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Pharmacokinetic Analyses 
If plasma concentrations of IW-1973 are detected, the PK parameters will be determined and 
tabulated, and summary statistics will be reported by treatment. 
Safety Analyses 
Adverse events will be summarized by system organ class (SOC), preferred term (PT), and 
treatment. Listings will be provided for treatment-related AEs, severe AEs, drug-related AEs, 
serious AEs, and AEs leading to study discontinuation. Descriptive statistics will be calculated 
on the safety parameters (ECG, vital signs, and clinical laboratory tests) by treatment. 
 
 

IW-1973 Tablet 
 
Ironwood Pharmaceuticals, Inc. 
Clinical Trial Protocol: C1973-201-P-03 
 
09 January 2017 
 
Confidential 
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SCHEDULE OF EVENTS 
Visit Days → 
Study Procedure ↓ 
Screening 
Period 
Clinic Period 
Follow-up Period 
Screening 
Visit 
(Day -28 
to -2) 
Check-
in 
Day -1 
1st day of cycle 
 
Days 
1, 4, 7, 10, 13, 16 
2nd day of cycle 
 
Days 
2, 5, 8, 11, 14, 17 
3rd day of cycle 
 
Days 
3, 6, 9, 12, 15, 18 
Discharge 
Day 19 
Follow-up Visit  
Day 32  
(± 2 days) 
End of 
Trial Visit 
Day 46 
(± 3 days) 
Informed consent signed 
X 
 
 
 
 
 
 
 
Inclusion/exclusion 
evaluation  
X 
X 
 
 
 
 
 
 
Demographics 
X 
 
 
 
 
 
 
 
Medical history 
X 
 
 
 
 
 
 
 
Physical exam 
X 
X 
 
 
 
X 
 
X 
HBsAg, HCV & HIV screen 
X 
 
 
 
 
 
 
 
Drug & alcohol screen (a) 
X 
X 
 
 
 
 
X 
 
Pregnancy test (b) 
X 
X 
 
 
 
 
X 
X 
Weight (W) & height (H) (c) 
W, H 
W 
W 
 
 
W 
W 
W 
12-lead ECG (d) 
X 
X 
pre: 0 (≤ 15m) 
pd: 1, 4h (± 15m) 
 
 
X 
 
 
Respiratory rate & oral temp 
(e) 
X 
X 
 
 
 
X 
preNG: 0 (≤ 15m) 
X 
Clinical chemistry, 
coagulation, hematology, 
urinalysis (f) 
X 
X 
 
 
 
X 
preEndoPAT (≥1h) 
 
Hemoglobin A1c  
X 
X 
 
 
 
X 
preEndoPAT (≥1h) 
 
Fasting blood glucose & 
serum insulin (g) 
X 
X 
 
pre: 0 (≤15m) 
 
X 
preEndoPAT (≥1h) 
 
Adverse event evaluations 
X 
X 
X 
X 
X 
X 
X 
X 
Prior & concomitant meds 
X 
X 
X 
X 
X 
X 
X 
X 
EndoPAT (h) 
X 
X 
 
 
pre: 0 (≤ 1h) 
pd: 4, 12h (±15m) 
 
preNG:  0 (≤ 1h) 
pdNG:  45m(±15m) 
 
Supine/standing BP & pulse 
supine only (i)  
X 
X 
pre: 0 (≤ 30m) 
pd:   1,2,4,8,12h 
(±10m) 
 
Supine only 
pre: 0 (≤ 30m) 
pd: 1,2,8h (±10m) 
24h 
(± 15m) 
Supine only 
preNG: 0 (≤ 30m) 
pdNG: 2h (+30m) 
X 

IW-1973 Tablet 
 
Ironwood Pharmaceuticals, Inc. 
Clinical Trial Protocol: C1973-201-P-03 
 
09 January 2017 
 
Confidential 
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ELIGIBILITY CRITERIA 
INCLUSION CRITERIA 
Patients must meet all of the following criteria to be eligible for enrollment in this study: 
1. Patient has signed an ICF before any study-specific procedures are performed.  
2. Patient is an ambulatory male or female aged 30 to 65 years at the Screening Visit. 
3. Female patient is not pregnant or breastfeeding at the time of the Screening Visit and 
Check-in. Negative serum pregnancy tests must be documented at the Screening Visit and at 
Check-in before dosing. 
4. Female patient must be postmenopausal, surgically sterile (ie, bilateral oophorectomy, 
hysterectomy, or tubal ligation), or, if of childbearing potential, agree to use 1 of the 
following methods of birth control from the date they sign the ICF until after the End of Trial 
Visit: 
a. Combination of 2 highly effective birth control methods (eg, condom with spermicide 
plus intrauterine device, condom with spermicide plus a diaphragm or cervical cap, 
hormonal contraceptive [including progesterone implant] combined with a barrier 
method) 
b. Maintenance of a monogamous relationship with a male partner who has been surgically 
sterilized by vasectomy (vasectomy procedure must have been conducted ≥ 60 days 
before the Screening Visit or confirmed via sperm analysis) plus a hormone or barrier 
method 
5. Patient’s body mass index score is > 20 and < 40 kg/m2 at the Screening Visit. 
6. Patient’s health is stable with no clinically significant findings on a physical examination, 
12-lead ECG, alcohol breathalyzer, and clinical laboratory tests (serum chemistry, 
hematology, coagulation, urine drug screen, and urinalysis) that would prevent participation 
in the trial. (Note: The Investigator will determine if a particular finding is clinically 
significant. In making this determination, the Investigator will consider whether the 
particular finding could prevent the patient from performing any of the protocol-specified 
assessments, could represent a condition that would exclude the patient from the study, could 
represent a safety concern if the patient participates in the study, or could confound the 
study-specified assessments.) 
7. Patient has type 2 (ie, adult onset) diabetes mellitus diagnosed by a physician or nurse 
practitioner ≥ 6 months before the Screening Visit and meets all of the following: 
a. Has been on a stable regimen of ≥ 1 medication for glycemic control, which may include 
long-acting insulin, with no change in medication for ≥ 12 weeks before Check-in and on 
a stable regimen (ie, same drug and same dose) for ≥ 28 days before Check-in with no 

IW-1973 Tablet 
 
Ironwood Pharmaceuticals, Inc. 
Clinical Trial Protocol: C1973-201-P-03 
 
09 January 2017 
 
Confidential 
Page 14 of 74 
indication that the regimen will need to be changed for the duration of the study. Per 
Investigator discretion, doses of supplemental short-acting insulin can be varied as 
needed to achieve adequate glycemic control.   
b. Has HbA1c level ≤ 10.5% and fasting (≥ 8 hours) blood glucose level ≤ 240 mg/dl at the 
Screening Visit and at Check-in; at Investigator discretion, if fasting blood glucose is 
> 240 mg/dl, the test may be repeated for determination of eligibility 
c. Has, in the clinical judgement of the Investigator, sufficient diabetes stability to 
participate in the trial 
8. Patient has hypertension diagnosed by a physician or nurse practitioner ≥ 6 months before the 
Screening Visit and meets all of the following: 
a. Has been on a stable regimen of ≥ 1 medication to control hypertension for ≥ 30 days 
before the Screening Visit with no indication that the regimen will need to be changed for 
the duration of the study. The medication(s) must include an ACEi or ARB and may 
include diuretics and/or calcium channel blockers. Other antihypertensive agents may be 
acceptable per the Investigator’s discretion. (See Section 3.5.6.1 for prohibited 
medications.) 
b. Has supine systolic BP of 120 to 160 mm Hg and supine diastolic BP of 70 to 
100 mm Hg at the Screening Visit  
c. Has, in the clinical judgement of the Investigator, sufficient hypertension stability to 
participate in the trial 
9. Patient has a valid reactive hyperemia index (RHI) measured by EndoPAT at the Screening 
Visit. (Note:  If initial EndoPAT assessment cannot be completed successfully at the 
Screening Visit, [ie, the RHI value cannot be confirmed], the test may be repeated after at 
least 3 hours have passed. All other instructions regarding EndoPAT testing should be 
followed.) 
10. Patient agrees to adhere to the study requirements. 
11. Patient has a negative hepatitis panel (hepatitis B surface antigen [HBsAg] and 
antihepatitis C virus [HCV]) and human immunodeficiency virus (HIV) antibody at the 
Screening Visit. 
12. Patient agrees to refrain from making any major lifestyle changes (eg, changing his or her 
exercise pattern) from the time of signature of the ICF to the End of Trial Visit. 
 

IW-1973 Tablet 
 
Ironwood Pharmaceuticals, Inc. 
Clinical Trial Protocol: C1973-201-P-03 
 
09 January 2017 
 
Confidential 
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EXCLUSION CRITERIA 
Patients who meet any of the following criteria will not be eligible to participate in the study: 
1. Patient has a clinically significant active or unstable medical condition that, in the opinion of 
the Investigator, would preclude trial participation, including active or unstable metabolic; 
hepatic; renal; hematological; pulmonary; cardiovascular; gastrointestinal; musculoskeletal; 
dermatological; urogenital; eye, ear, nose, and throat; psychiatric; or neurological conditions. 
2. Patient is on medication(s) that when co-administered with a soluble guanylate cyclase (sGC) 
stimulator, could increase the risk of hypotension. These include (but may not be limited to) 
nitrates, nitroglycerin, direct vasodilators (including hydralazine or systemic minoxidil), or 
phosphodiesterase (PDE) 5 inhibitors (including sildenafil, tadalafil, and vardenafil), alpha 
adrenergic blockers, riociguat, and sodium-glucose co-transporter 2 (SGLT2) inhibitors. 
Patients should not take these medications from 6 days before Check-in to the End of Trial 
Visit.  
3. Patient has evidence of severe or active end-organ damage attributable to diabetes (eg, active 
diabetic nephropathy, retinopathy, or neuropathy) at the Screening Visit or at Check-in. 
4. Patient has evidence of active end-organ morbidity associated with uncontrolled hypertension 
(eg, progressive kidney insufficiency, myocardial infarction, or stroke) at the Screening Visit 
or at Check-in, or has had an in-patient hospitalization for a cardiovascular, renal, or 
metabolic cause in the 6 months before the Screening Visit. 
5. Patient has orthostatic decrease in systolic BP of > 20 mm Hg or orthostatic decrease in 
diastolic BP of > 15 mm Hg at the Screening Visit.  
6. Patient has severe renal insufficiency (eg, current or past need for dialysis), has undergone 
renal transplantation, or has planned renal transplantation.  
7. Patient has a history of malignancy, diagnosed or known to be active or actively treated 
within the past 5 years, other than resected lesions of low malignant potential, such as basal 
cell skin cancers. 
8. Patient has bleeding diathesis or history of clinically significant bleeding episodes (eg, 
gastrointestinal bleed) in the 12 months before the Screening Visit. 
9. Patient has a 12-lead ECG demonstrating severe bradycardia (heart rate < 40 beats per 
minute) or QTcF is ≥ 450 msec for male patients or is ≥ 470 msec for female patients at the 
Screening Visit. (NOTE: If on initial ECG, QTcF exceeds the limit, the ECG will be repeated 
2 more times, and the average of the 3 QTcF values will be used to determine the patient's 
eligibility). 
10. Patient has alanine aminotransferase (ALT) or aspartate aminotransferase (AST) levels 
> 2 times the upper limit of normal as defined by the laboratory or creatinine level > 1.5 
times the normal as defined by the laboratory at the Screening Visit. 

IW-1973 Tablet 
 
Ironwood Pharmaceuticals, Inc. 
Clinical Trial Protocol: C1973-201-P-03 
 
09 January 2017 
 
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11. Patient has a history of clinically significant hypersensitivity or allergies to any of the 
inactive ingredients contained in the active or placebo drug products. 
12. Patient has a history of active alcoholism or drug addiction during the year before the 
Screening Visit, or has a positive drug screen at the Screening Visit or at Check-in.  
13. Patient has previously received IW-1973 in a study or has received an investigational drug 
during the 30 days or 5 half-lives of that investigational drug (whichever is longer) before the 
Screening Visit or is planning to receive another investigational drug at any time during the 
study. 
14. Patient is an active smoker or has used any nicotine-containing products (cigarettes, 
e-cigarettes, vape pens, cigars, chewing tobacco, gum, patches) during the 6 months before 
Check-in. Use of nicotine is excluded during the study until after the End of Trial Visit. 
15. Patient has consumed grapefruit or grapefruit juice during the 72 hours before Check-in, 
taken vitamins or herbal supplements during the 7 days before Check-in, or taken any 
supplements for the treatment of erectile dysfunction during the 14 days before Check-in. 
Grapefruit, grapefruit juice, vitamins, herbal supplements, or any supplements for the 
treatment of erectile dysfunction are excluded during the study until after the End of Trial 
Visit. 
16. Patient has consumed any alcohol-containing foods or beverages during the 7 days before 
Check-in. Use of alcohol-containing foods or beverages is prohibited from 7 days before 
Check-in through Discharge. In the clinic, patient may consume up to 2 cups of coffee or tea 
per day but not within 1 hour of study drug administration or within 3 hours before EndoPAT 
assessments.  
17. Patient has donated blood products during the 6 weeks before Check-in. 
18. Patient has received blood products during the 2 months before Check-in. 
19. Patient has undergone a surgical procedure during the 30 days before Check-in, other than 
minor dermatologic procedures. 
20. Patient has an acute or chronic condition that, in the Investigator’s opinion, would limit the 
patient’s ability to complete or participate in this clinical study. 
21. Patient is involved in the conduct and administration of this study as an Investigator, 
sub-Investigator, study coordinator, other study staff, or Sponsor member. 
22. Patient will not be able to adhere to the trial assessment schedule, or, in the clinical judgment 
of the Investigator, the patient is otherwise not suitable for trial participation. 

IW-1973 Tablet 
 
Ironwood Pharmaceuticals, Inc. 
Clinical Trial Protocol: C1973-201-P-03 
 
09 January 2017 
 
Confidential 
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TABLE OF CONTENTS 
STUDY IDENTIFICATION ...........................................................................................................2 
SYNOPSIS .......................................................................................................................................3 
STUDY SCHEMATIC ....................................................................................................................9 
SCHEDULE OF EVENTS ............................................................................................................10 
ELIGIBILITY CRITERIA.............................................................................................................13 
INCLUSION CRITERIA.........................................................................................................13 
EXCLUSION CRITERIA .......................................................................................................15 
LIST OF ABBREVIATIONS AND DEFINITIONS OF TERMS ................................................21 
1. 
INTRODUCTION .................................................................................................................24 
1.1 
STUDY RATIONALE ................................................................................................24 
1.1.1 
Background ........................................................................................................24 
1.1.2 
IW-1973 .............................................................................................................25 
1.1.3 
Study Population ................................................................................................25 
1.2 
IW-1973: NONCLINICAL AND CLINICAL BACKGROUND ...............................26 
1.2.1 
Nonclinical .........................................................................................................26 
1.2.2 
Clinical Studies ..................................................................................................27 
2. 
STUDY OBJECTIVES ..........................................................................................................30 
3. 
INVESTIGATIONAL PLAN ................................................................................................31 
3.1 
OVERALL STUDY DESIGN AND PLAN ................................................................31 
3.2 
DISCUSSION OF STUDY DESIGN INCLUDING THE CHOICE OF 
CONTROL GROUPS ..................................................................................................32 
3.3 
STUDY DURATION ..................................................................................................32 
3.4 
STUDY POPULATION SELECTION .......................................................................33 
3.4.1 
Study Population ................................................................................................33 
3.4.1.1 
Type 2 Diabetes Requirement ..................................................................33 
3.4.1.2 
Hypertension Requirement ......................................................................33 
3.4.1.3 
Endothelial Function Assessment Requirements .....................................34 
3.4.2 
Removal of Patients from Therapy or Assessment ............................................34 
3.4.3 
Replacement Procedures ....................................................................................35 
3.5 
STUDY TREATMENT(S) ..........................................................................................35 
3.5.1 
Description of Treatment(s) ...............................................................................35 
3.5.1.1 
Study Drug ...............................................................................................35 
3.5.1.2 
Nitroglycerin ............................................................................................36 
3.5.2 
Selection of Dosage in the Study .......................................................................36 
3.5.3 
Selection and Timing of Dose for Each Patient .................................................37 
3.5.4 
Blinding..............................................................................................................38 
3.5.5 
Concomitant Medications ..................................................................................38 

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Ironwood Pharmaceuticals, Inc. 
Clinical Trial Protocol: C1973-201-P-03 
 
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3.5.6 
Restrictions ........................................................................................................38 
3.5.6.1 
Prior Therapy and Prohibited Medications ..............................................38 
3.5.6.2 
Vitamins and Supplements ......................................................................39 
3.5.6.3 
Fluid and Food Intake and Nicotine-containing Product Use ..................39 
3.5.6.4 
Patient Activity Restrictions ....................................................................39 
3.6 
STOPPING CRITERIA ...............................................................................................40 
3.7 
STUDY PROCEDURES .............................................................................................40 
3.7.1 
Informed Consent...............................................................................................40 
3.7.2 
Medical History .................................................................................................41 
3.7.3 
Safety Assessments ............................................................................................41 
3.7.3.1 
Physical Examination...............................................................................41 
3.7.3.2 
Vital Signs ................................................................................................42 
3.7.3.3 
Electrocardiograms ..................................................................................42 
3.7.3.4 
Clinical Laboratory Tests .........................................................................42 
3.7.3.5 
Adverse Events ........................................................................................44 
3.7.3.6 
Serious Adverse Events ...........................................................................45 
3.7.3.7 
Recording Adverse Events .......................................................................46 
3.7.3.8 
Reporting Serious Adverse Events ..........................................................47 
3.7.4 
Pharmacodynamic Assessments ........................................................................48 
3.7.4.1 
Hemodynamics ........................................................................................49 
3.7.4.2 
Endothelial Function ................................................................................49 
3.7.4.3 
Platelet Function Assessment ..................................................................50 
 
 
 
 
3.7.5 
Pharmacokinetic Assessments ...........................................................................50 
3.8 
STUDY ACTIVITIES .................................................................................................51 
3.8.1 
Screening Period (Days –28 to Day -2) .............................................................51 
3.8.1.1 
Screening Visit (Days –28 to Day -2) ......................................................51 
3.8.2 
Clinic Period (Days -1 to Day 19) .....................................................................52 
3.8.2.1 
Check-in (Day -1) ....................................................................................52 
3.8.2.2 
First Day of Each 3-day Dosing Cycle (Days 1, 4, 7, 10, 13, 16) ...........53 
3.8.2.3 
Second Day of Each 3-day Dosing Cycle (Days 2, 5, 8, 11, 14, 17) .......53 
3.8.2.4 
Third Day of Each 3-day Dosing Cycle (Days 3, 6, 9, 12, 15, 18) ..........54 
3.8.2.5 
Discharge (Day 19) ..................................................................................54 
3.8.3 
Follow-up Period (Day 20 to Day 46 ±3) ..........................................................55 
3.8.3.1 
Follow-up Visit (Day 32 ±2) ....................................................................55 
3.8.3.2 
End of Trial Visit (Day 46 ± 3) ................................................................56 
3.9 
STATISTICAL METHODS ........................................................................................56 

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Clinical Trial Protocol: C1973-201-P-03 
 
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3.9.1 
Determination of Sample Size ...........................................................................56 
3.9.2 
Analysis Populations ..........................................................................................56 
3.9.2.1 
 Safety Population ....................................................................................56 
3.9.2.2 
PK Population ..........................................................................................56 
3.9.2.3 
PD Population ..........................................................................................56 
3.9.3 
Statistical Methods .............................................................................................57 
3.9.3.1 
General Considerations ............................................................................57 
3.9.3.2 
Patient Disposition, Demographics, and Baseline Characteristics ..........57 
3.9.3.3 
Pharmacodynamic Analyses ....................................................................57 
3.9.3.4 
Safety Analyses ........................................................................................58 
3.9.3.5 
Pharmacokinetic Analyses .......................................................................59 
3.9.3.6 
Interim Analysis .......................................................................................59 
3.9.3.7 
Computer Methods...................................................................................59 
3.10 
CHANGES IN THE CONDUCT OF THE STUDY OR PLANNED ANALYSES ...59 
4. 
ETHICAL CONSIDERATIONS ...........................................................................................61 
4.1 
INSTITUTIONAL REVIEW BOARD........................................................................61 
4.2 
PATIENT INFORMATION AND INFORMED CONSENT .....................................61 
5. 
INVESTIGATORS AND STUDY ADMINISTRATIVE STRUCTURE ............................63 
5.1 
GENERATION OF STUDY RECORDS ....................................................................63 
5.2 
DATA QUALITY ASSURANCE ...............................................................................64 
5.3 
ELECTRONIC CASE REPORT FORMS AND DATA MANAGEMENT ...............64 
5.4 
STUDY MONITORING .............................................................................................64 
6. 
STUDY SPONSORSHIP ......................................................................................................66 
6.1 
INVESTIGATOR AND STUDY TERMINATION ...................................................66 
6.2 
REPORTING AND PUBLICATION ..........................................................................66 
7. 
INVESTIGATOR OBLIGATIONS ......................................................................................67 
7.1 
DOCUMENTATION ..................................................................................................67 
7.2 
PERFORMANCE ........................................................................................................69 
7.3 
ACCOUNTABILITY ..................................................................................................69 
7.4 
RETENTION AND REVIEW OF RECORDS ...........................................................69 
7.5 
PATIENT CONFIDENTIALITY ................................................................................70 
8. 
REFERENCE LIST ...............................................................................................................71 
9. 
SPONSOR SIGNATURE ......................................................................................................73 
10. INVESTIGATOR SIGNATURE...........................................................................................74 
 
 
 

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LIST OF IN-TEXT TABLES 
Table 1. 
Key Study Participants .........................................................................................2 
Table 2. 
Clinical Laboratory Tests ...................................................................................43 
 
 

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LIST OF ABBREVIATIONS AND DEFINITIONS OF TERMS 
Abbreviation 
Term 
ABPM 
ambulatory blood pressure monitoring 
ACEi 
angiotensin-converting enzyme inhibitor 
AE 
adverse event 
ALT 
alanine aminotransferase 
ARB 
angiotensin receptor blocking agent 
AST 
aspartate aminotransferase 
AUCinf 
area under the plasma concentration time curve extrapolated to infinity 
AUCtau 
area under the plasma concentration time curve during a dosing interval (tau) 
BP 
blood pressure 
BUN 
blood urea nitrogen 
CBC 
complete blood count 
cGMP 
cyclic guanosine 3’, 5’-monophosphate 
Cmax 
maximum observed plasma concentration 
Ctrough 
trough plasma concentration observed at the end of a dosing interval 
DNA 
deoxyribonucleic acid 
ECG 
electrocardiogram 
eCRF 
electronic case report form 
EDC 
electronic data capture 
FDA 
Food and Drug Administration 
GCP 
good clinical practice 
GGT 
gamma glutamyl transferase   
GLP 
good laboratory practice 
GTP 
guanosine triphosphate 
HbA1c 
hemoglobin A1c (glycated hemoglobin) 
HBsAg 
hepatitis B surface antigen 
HCV 
hepatitis C virus 
HDPE 
high-density polyethylene 
hERG 
ether-a-go-go related gene 
HIV 
human immunodeficiency virus 

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Abbreviation 
Term 
HPF 
high power field 
IC50 
half maximal inhibitory concentration 
ICF  
informed consent form 
ICH 
International Conference on Harmonization 
IRB 
Institutional Review Board 
kg 
kilogram 
kg/m2 
kilograms/meters squared (body mass index) 
LDH 
lactate dehydrogenase  
MAD 
multiple ascending dose 
MCH 
mean corpuscular hemoglobin 
MCHC 
mean corpuscular hemoglobin concentration 
MCV 
mean corpuscular volume 
MedDRA 
Medical Dictionary for Regulatory Activities 
mg 
milligram 
mL 
milliliter 
mm Hg 
millimeters of mercury 
MPV 
mean platelet volume 
msec 
millisecond 
NG 
nitroglycerin 
NO 
nitric oxide 
pd 
postdose 
PD 
pharmacodynamic(s) 
PDE 
phosphodiesterase 
PK 
pharmacokinetic(s) 
PT 
preferred term 
QTcF 
QT interval corrected using Fridericia’s formula 
RBC 
red blood cell 
RDW 
red blood cell distribution width 
RHI 
reactive hyperemia index 
SAD 
single ascending dose 

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Abbreviation 
Term 
SAE 
serious adverse event 
SAS® 
Statistical Analysis System 
sGC 
soluble guanylate cyclase 
SNP 
single nucleotide polymorphisms 
SOC 
system organ class 
tau 
dosing interval 
t1/2 
apparent terminal phase half-life 
Tmax 
time of maximum observed plasma concentration 
UGT 
uridine diphosphate–glucuronosyl transferase 
WBC 
white blood cell 
 

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1. 
INTRODUCTION 
1.1 
STUDY RATIONALE 
1.1.1 
Background 
The vascular endothelium is a single continuous layer of endothelial cells that lines the blood 
vessels. It serves as a barrier between the circulating blood in the vessel lumen and the vascular 
smooth muscle in the vessel wall. Through the production of vasoactive molecules, the 
endothelium regulates vascular tone, permeability, inflammation, cellular adhesion, and 
thromboresistance, thus maintaining vascular homeostasis.(reviews in 1-3) Modulation of 
vascular tone balances vasoconstriction and vasodilation in response to chemical and mechanical 
stimuli. (review in 4) In particular, vasodilation is critical for reducing arterial blood pressure 
(BP) and adapting organ perfusion in response to flow-mediated shear stress associated with 
changes in cardiac output or postocclusion restoration of blood flow (reactive 
hyperemia).(review in 5,6) 
Nitric oxide (NO) is the primary mediator of vasodilation. The release of NO by endothelial cells 
activates the heterodimeric enzyme, soluble guanylate cyclase (sGC), to convert guanosine 
triphosphate (GTP) to cyclic guanosine-3’, -5’-monophosphate (cGMP). In turn, cGMP 
stimulates protein kinases, which decrease intracellular calcium levels and relax the vascular 
smooth muscle. The cGMP is then degraded by phosphodiesterase (PDE) enzymes. (review in 7) 
The NO-sGC-cGMP pathway is the main mechanism by which NO regulates vasodilation.  
Impaired vasodilation is the hallmark of endothelial dysfunction and reflects reduced NO 
production or activity. Endothelial dysfunction underlies the earliest development of 
atherosclerosis; is associated with multiple cardiovascular risk factors including type 1 and 2 
diabetes, obesity, hypertension, hypercholesterolemia, metabolic syndrome, and chronic 
smoking; and is a predictor of cardiovascular disease.(1,2,4,5) 
Endothelial dysfunction may be improved, both acutely and chronically, by treatment with 
therapeutic agents that work by inhibiting vasoconstriction or by promoting vasodilation.(5) 
Agents that promote vasodilation act on various components of the NO-sGC-cGMP pathway. 
For example, organic nitrates exploit the beginning of the pathway by providing exogenous NO, 
and PDE5 inhibitors exploit the end by preventing degradation of cGMP thereby prolonging its 

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activity.(2,8,9) sGC, a central enzyme in this pathway, may also be targeted. Agonists of sGC 
may compensate for NO deficiency by acting directly on sGC to increase cGMP 
production.(5,10) By restoring endothelial function, sGC stimulators may be useful for treating 
and/or preventing a broad range of diseases that may ensue from dysfunction in this fundamental 
process.(reviews in 11,12) 
1.1.2 
IW-1973 
Ironwood Pharmaceuticals is developing IW-1973, an orally administered stimulator of soluble 
guanylate cyclase (sGC), for the treatment of cardiovascular disorders modulated by the 
NO-cGMP-sGC signaling pathway.  
1.1.3 
Study Population 
This exploratory, proof-of-mechanism study aims to evaluate the effect of the sGC stimulator, 
IW-1973, on impaired endothelial function by assessing reactive hyperemia, an endothelium-
mediated vascular response, both before and after treatment. Endothelial function will be 
evaluated by measuring pulsatile volume changes in the small vessels of the fingertip after 
brachial artery occlusion using an EndoPAT™ instrument (Itamar Medical; Caesarea, Israel). 
To investigate the hypothesis that IW-1973 will improve impaired endothelial function, the study 
requires a sample of patients who may have impaired endothelial function. Therefore, this study 
will enroll patients with type 2 diabetes and hypertension, a population that commonly has some 
degree of endothelial dysfunction. Type 2 diabetes is a chronic metabolic disorder in which the 
body does not use insulin effectively, leading to hyperglycemia and glucose intolerance. The 
prevalence of diabetes in the United States (US) is 9.3%, or about 29.1 million people, and 95% 
of diagnosed cases are type 2.(13) This multifactorial disease is associated with numerous 
comorbidities, including hypertension, obesity, hyperlipidemia, chronic kidney disease, and 
cardiovascular disease. Nearly all diabetic patients have at least 1 comorbidity and almost 90% 
have at least 2.(14) Hypertension is the most common comorbid condition and may affect over 
80% of patients with type 2 diabetes.(14) Hypertension in diabetic patients increases the risk of 
cardiovascular disease and associated complications such as stroke, coronary artery disease, and 
peripheral vascular disease. In addition, hypertension in diabetic patients also increases the risk 
of microvascular diseases including retinopathy, nephropathy, and neuropathy.(reviews in 15,16) 

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Endothelial dysfunction has a complex relationship to diabetes, hypertension, and their 
comorbidities because it is both a cause and an effect. Additionally, the combination of disorders 
often present in diabetic patients leads to acceleration and exacerbation of endothelial 
dysfunction, which in turn leads to worsened disease states. Improving endothelial function in 
these patients may help avert this cascade of effects. 
1.2 
IW-1973: NONCLINICAL AND CLINICAL BACKGROUND 
1.2.1 
Nonclinical 
IW-1973 is a potent and selective stimulator of sGC. In vitro, IW-1973 was shown to sensitize 
sGC to endogenous NO, and to directly stimulate sGC independently of NO. IW-1973 also 
potently relaxed precontracted human subcutaneous resistance arteries ex vivo. Oral 
administration of IW-1973 to normotensive and spontaneously hypertensive rats and to 
normotensive dogs was shown to elicit a dose-dependent decrease in systolic, diastolic, and 
mean arterial BP, as well as a concomitant rise in heart rate. 
 
 
 
 
 
 
 
 
 
 
 
 
In Good Laboratory Practices (GLP) safety pharmacology studies, IW-1973-related effects 
observed in neurobehavioral (decreased rearing, locomotor activity) and cardiovascular 
(decreased BP and associated increased heart rate) functional studies were consistent with the 
expected pharmacology of IW-1973.    

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2. 
STUDY OBJECTIVES 
In adult patients (N = 12) with stable type 2 diabetes mellitus and controlled hypertension:  
• To evaluate the safety and tolerability of escalating doses of IW-1973  
• To evaluate the impact of escalating doses of IW-1973 on 
- 
endothelial function using EndoPAT to measure fingertip small vessel pulse volume 
- 
BP and heart rate 
 

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3. 
INVESTIGATIONAL PLAN 
3.1 
OVERALL STUDY DESIGN AND PLAN 
This is an open-label, single-center study with a Screening Period, Clinic Period, and a 
Follow-up Period (Study Schematic). The study will enroll 12 patients (at least 4 men and 
4 women) with type 2 diabetes, hypertension, and impaired endothelial function (see Eligibility 
Criteria); the 12 patients may be enrolled separately. Additional patients (approximately 2 to 6) 
may be checked into the Study Center on Day -1 as back-ups. If the back-up patients are not 
needed, they will be discharged from the Study Center on Day -1 or Day 1. Patients will receive 
once-daily study drug for 6, sequential, 3-day dosing cycles (18 total days) starting with placebo 
(2 tablets) for 3 days (baseline) and then progressing to 5 escalating dose levels of IW-1973 (10, 
20, 30, 40, and 50 mg) for 3 days each (see Study Schematic).  
Each patient will progress through 3 study periods. 
Screening Period: The Screening Period will begin with the signature of the informed consent 
form (ICF) at the Screening Visit and will last 1 to 27 days. Patients will undergo preliminary 
screening procedures to determine their eligibility for the study at the Screening Visit. The end of 
the Screening Period will coincide with the beginning of the Clinic Period at Check-in.   
Clinic Period: The Clinic Period will begin at Check-in on Day -1 and will end at Discharge on 
Day 19. Patients who meet eligibility criteria based on Screening Visit assessments will be 
admitted to the Study Center on Day -1 for procedures to confirm eligibility. Patients will be 
confined to the Study Center and will receive a standard diet for diabetics until Discharge. On 
Days 1 to 18, following an overnight fast of at least 8 hours, 12 eligible patients will receive 
once-daily study drug (see Section 3.5.3). Safety (AE collection, vital signs, fasting glucose, 
serum insulin, electrocardiograms [ECGs],) and PK assessments, including blood collections, 
will be performed at prespecified times (see Schedule of Events). Pharmacodynamic assessments 
will be performed on a 3-day cycle that will repeat for each of the 6 dosing cycles (see Study 
Schematic and Schedule of Events): the first day will include supine and standing cuff BP and 
pulse measurements; the second day will include ambulatory BP monitoring (ABPM), and the 
third day will include EndoPAT assessments of endothelial function. In addition, blood samples 
will be collected for platelet function testing (PFA-100®) 
 

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 (see Schedule of Events). On Day 19, after assessments have been 
completed, patients will be discharged from the Study Center at the Investigator’s discretion.  
Follow-up Period: The Follow-up Period will begin immediately after Discharge of the patient 
from the Study Center and will last for 27 (± 3) days. Patients will return to the Study Center 
14 (± 2) days after the final dose of study drug (Day 32) for the Follow-up Visit. At this visit, in 
addition to safety and PK assessments, patients will have EndoPAT assessments before and after 
a 0.4 mg dose of sublingual nitroglycerin to test endothelium-independent vasodilation. Patients 
will remain in the Study Center for at least 2 hours until BP and pulse return to predose or 
acceptable, safe levels. Patients will return to the Study Center 28 (± 3) days after the final dose 
of study drug (Day 46) for the End of Trial Visit for final safety and PK assessments (see 
Schedule of Events). 
3.2 
DISCUSSION OF STUDY DESIGN INCLUDING THE CHOICE OF 
CONTROL GROUPS 
In this open-label study, patients will undergo 3 days of placebo dosing before beginning dosing 
with investigational product, thereby serving as their own control. This design is sufficient for 
the exploratory objectives of this study. 
3.3 
STUDY DURATION  
Patients will receive once-daily study drug for 18 days:  placebo for 3 days and escalating doses 
of IW-1973 for 15 days. Patients will be in clinic for 20 days, from Check in on Day -1 to 
Discharge on Day 19. Total patient participation will be 45 to 77 days including Screening, 
Clinic, and Follow-up Periods. 

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3.4 
STUDY POPULATION SELECTION 
3.4.1 
Study Population 
This study will enroll 12 patients with type 2 diabetes and hypertension as defined below; in 
addition, patients must have impaired endothelial function at baseline. Refer to Eligibility 
Criteria for full inclusion and exclusion requirements. 
3.4.1.1 
Type 2 Diabetes Requirement 
Patients must have type 2 diabetes diagnosed by a physician or nurse practitioner no less than 
6 months before the Screening Visit and must have been on a stable regimen of at least 
1 medication specifically for control of glycemia, either oral or injectable, for at least 12 weeks 
before the Screening Visit. To be eligible, patients must have a hemoglobin A1c (HbA1c) level 
of ≤ 10.5% and a fasting (≥ 8 hours) blood glucose level of ≤ 240 mg/dl.    
All screened patients with HbA1c or blood glucose levels in the abnormal range (as defined by 
the laboratory) at any point during the trial will be informed of these abnormal lab values, and 
with the patient’s permission, this information will be shared with a designated healthcare 
provider at the conclusion of their participation in the trial. 
3.4.1.2 
Hypertension Requirement 
In addition to type 2 diabetes, patients must have hypertension diagnosed by a physician or nurse 
practitioner no less than 6 months before the Screening Visit and must have been on a stable 
regimen of at least one medication for BP control for at least 30 days before the Screening Visit; 
the medication(s) must include an angiotensin-converting enzyme inhibitor (ACEi) or 
angiotensin receptor blocking agent (ARB). Patients must have systolic BP of 120 to 160 mm Hg 
and diastolic BP of 70 to 100 mm Hg. 
All patients with systolic pressures ≥ 140 mm Hg or diastolic pressures ≥ 90 mm Hg at the end 
of trial visit will be referred to their healthcare provider. All patients with systolic pressure ≥ 160 
mm Hg or diastolic pressure ≥ 100 mm Hg at any point during the study,  who, in the clinical 
judgement of the Investigator, are experiencing or at immediate risk for end-organ events will be 
immediately referred to an appropriate healthcare provider.    

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3.4.1.3 
Endothelial Function Assessment Requirements 
The trial will investigate the hypothesis that escalating doses of the sGC stimulator, IW-1973, 
will improve endothelial vascular function. Endothelial function will be defined by the reactive 
hyperemic index (RHI) determined using the EndoPAT device, which assesses changes in 
fingertip small vessel pulse volume by tonometry.  
3.4.2 
Removal of Patients from Therapy or Assessment 
A premature discontinuation will occur when a patient who has signed the ICF and has received 
at least 1 dose of study drug ceases participation in the study, regardless of circumstances, before 
completion of Clinic Period. 
A patient will be considered to have completed the study after completing the Clinic Period. 
Patients will be informed that they are free to withdraw from the study at any time and for any 
reason. The Investigator may remove a patient from the study if, in the Investigator’s opinion, it 
is not in the best interest of the patient to continue the study. Patients may also be discontinued 
from the study by the Investigator or the Sponsor at any time for any reason, including the 
following: 
• Adverse event(s) 
• Protocol violation, including lack of compliance 
• Lost to follow-up (every effort must be made to contact the patient; a certified letter must be 
sent) 
• Withdrawal of consent (attempts should be made to determine the reason for the patient 
withdrawing consent if possible) 
• Study termination by the Sponsor 
• Other reasons (eg, administrative reasons or pregnancy) 
 
The Sponsor will be notified of any patient discontinuation after first dose of study drug. The 
date the patient is withdrawn from the study and the reason for discontinuation will be recorded 
on the study termination form of the electronic case report form (eCRF). Patients who 

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discontinue from the study will be followed until resolution of all of their AEs or until the 
unresolved AEs are judged by the Investigator to have stabilized. 
If a patient does not return for a scheduled visit, the study center should contact the patient. An 
effort must be made to contact the patient, including sending a certified letter. In every case, the 
patient outcome, including lost to follow-up information, will be documented. 
3.4.3 
Replacement Procedures 
Patients withdrawing from the study after first dose will not be replaced. 
3.5 
STUDY TREATMENT(S) 
3.5.1 
Description of Treatment(s) 
3.5.1.1 
Study Drug 
3.5.1.1.1 
Investigational Product 
The investigational product, IW-1973 Tablet, is a 5 mg oral tablet. Doses will comprise multiple 
tablets (eg, a 30 mg dose will be six 5 mg tablets). 
3.5.1.1.2 
Placebo 
Placebo will match the IW-1973 Tablet in appearance. During the placebo cycle, doses will 
comprise 2 placebo tablets.  
3.5.1.1.3 
Packaging and Labeling 
IW-1973 Tablet and placebo to match will be supplied to the site in 60cc high-density 
polyethylene (HDPE) induction sealed bottles, 35 tablets per bottle. Bottles will be supplied as 
open label to the clinical site. 
3.5.1.1.4 
Storage and Accountability 
IW-1973 Tablet and placebo to match will be shipped under refrigerated conditions, 2°C - 8°C 
(36 - 46°F). 
IW-1973 Tablet and placebo to match must be stored under refrigerated conditions, 2°C - 8°C 
(36°F - 46°F) per the instructions in the study’s Pharmacy Manual. Once opened the bottles will 

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be kept at room temperature storage (15 -30°C/59-86°F) for up to 30 days. Any deviation from 
these storage conditions must be reported to Ironwood and use of the study drug suspended until 
authorization for its continued use has been provided by Ironwood. 
The Investigator must ensure that the receipt and use of all study drug supplied is recorded and 
must supervise the storage and allocation of these supplies. All study drug supplies must be 
retained in a locked room that may only be accessed by the pharmacist, Investigator, or other 
duly designated persons. Study drug must not be used outside the context of this protocol, and 
under no circumstances should the Investigator or study center personnel allow the supplies to be 
used other than as directed by this protocol without prior authorization from Ironwood. 
3.5.1.2 
Nitroglycerin 
Nitroglycerin, 0.4 mg, sublingual tablet, which will be administered at the Follow-up Visit to test 
endothelium-independent vasodilation, will be supplied by the Study Center and will be stored in 
accordance with manufacturer’s instructions. 
3.5.2 
Selection of Dosage in the Study 
In this Phase 2a exploratory study, 5 escalating doses of IW-1973 (10, 20, 30, 40, and 50 mg) 
will be studied in sequential 3-day cycles. In the Phase 1a and Phase 1b studies in healthy 
volunteers, dose levels ranging from 10 to 40 mg were tolerated. In the Phase 1a SAD study 
(ICP-1973-101), 35 mg was considered the maximum single tolerated dose and in the Phase 1b 
MAD study (ICP-1973-102), 40 mg in the tablet formulation was considered the maximum 
tolerated repeat dose. (In the Phase 1b study, 1 subject in Cohort 4 [Low Dose (≤ 0.5 mg/kg [in 
5-mg increments])/High Dose (40 mg or ≤ 0.5 mg/kg for body weight ≥ 90 kg, whichever 
greater)] received 50 mg IW-1973 for 7 days as the High (up-titration) Dose. This subject 
reported no AEs.) In this Phase 2a trial, gradual dose escalation starting with a low dose may 
satisfy 2 secondary objectives: 1) to identify the minimum dose at which an improvement in 
endothelial function is detected, and 2) to determine if gradual escalation improves tolerability. 
The highest planned dose, 50 mg, exceeds the maximum tolerated dose level in healthy 
volunteers but is planned for evaluation in this Phase 2 study because gradual escalation may 
allow a 50 mg dose to be tolerated and, in addition, the maximum tolerated dose in patients may 

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be higher than in healthy volunteers. This study will be conducted in clinic and will employ 
stopping criteria (Section 3.6) to ensure the safety of patients. 
3.5.3 
Selection and Timing of Dose for Each Patient 
Patients will receive orally administered study drug at approximately the same time 
(± 15 minutes) every day in the morning (8 to 10AM), after an overnight fast of at least 8 hours. 
(Note: for each patient, the first dose on Day 1 may be administered between 8 and 10AM; 
thereafter, doses on Days 2 to 18 must be administered within 15 minutes of the time of dosing 
on Day 1.) Patients are allowed to take multiple tablets together. Permitted concomitant 
medications that the patient may be taking in the morning should be taken at the same time as 
study drug. Breakfast should begin within 30 minutes after dosing.   
On the 3rd day of each cycle the predose EndoPAT assessment (from the time the EndoPAT 
recording starts) should occur no more than 1 hour before study drug administration; predose BP 
and pulse measurements should be measured no more than 30 minutes before study drug 
administration. 
In summary, the order of procedures around dosing on the 1st and 2nd day of each cycle should 
be:  
• Overnight fast of at least 8 hours 
• Predose safety, PK, and PD assessments 
• Study drug and allowed concomitant medication administration between 8 and 10AM at the 
same time (± 15 minutes) every day 
• Breakfast begins within 30 minutes after study drug administration 
 
The order of procedures around dosing on the 3rd day of each cycle should be:  
• Overnight fast of at least 8 hours 
• Predose EndoPAT no more than 1 hour before study drug administration (from time 
EndoPAT recording starts) 
• Predose BP and pulse measurements no more than 30 minutes before study drug 
administration 

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• Study drug and allowed concomitant medication administration between 8 and 10AM at the 
same time (± 15 minutes) every day 
• Breakfast begins within 30 minutes after study drug administration 
 
3.5.4 
Blinding 
This is an open-label study. 
3.5.5 
Concomitant Medications 
At the Screening Visit, the following information will be recorded for each patient: 
• All medications the patient is taking (ongoing)  
• All prior medications taken during the 30 days before the Screening Visit 
 
Permitted medications that the patient may be taking in the morning should be taken at the same 
time as study drug. Permitted concomitant medications that the patients may be taking at other 
times of day should not be taken 1 hour before or during EndoPAT assessments. 
Any medication taken by a patient during the course of the study (beginning at the Screening 
Visit), including any new medications added or changes in medications previously reported, the 
time of use, and the reason for use will be documented in the source documents and the eCRF. 
3.5.6 
Restrictions 
3.5.6.1 
Prior Therapy and Prohibited Medications 
Medication(s) that when co-administered with an sGC stimulator could increase the risk of 
hypotension are prohibited from 6 days before Check-in through the End of Trial Visit. These 
medications include (but may not be limited to) nitrates, nitroglycerin, direct vasodilators 
(including hydralazine or systemic minoxidil), or phosphodiesterase (PDE) 5 inhibitors 
(including sildenafil, tadalafil, and vardenafil), alpha adrenergic blockers, riociguat, and 
sodium-glucose co-transporter 2 (SGLT2) inhibitors.  

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3.5.6.2 
Vitamins and Supplements 
All vitamins and herbal supplements are prohibited within 7 days before Check-in through the 
End of Trial Visit. Supplements for the treatment of erectile dysfunction are prohibited within 
14 days before Check-in through the End of Trial Visit. 
3.5.6.3 
Fluid and Food Intake and Nicotine-containing Product Use 
The following food, fluid, and tobacco restrictions apply: 
• All nicotine-containing products (eg, cigarettes, e-cigarettes, vape pens, cigars, chewing 
tobacco, gum, patches) are prohibited within 6 months before Check-in through the End of 
Trial Visit. 
• All alcohol-containing foods or beverages are prohibited within the 7 days before Check-in 
through Discharge. 
• Patients may consume up to 2 cups of coffee or tea per day but not within 1 hour of study 
drug administration or within 3 hours before EndoPAT assessments. 
• Grapefruit and grapefruit juice are prohibited within 72 hours before Check-in through the 
End of Trial Visit. 
• Food is not allowed for 8 hours before study drug administration. Breakfast should begin 
within 30 minutes of study drug administration. 
• Food is not allowed 8 hours before clinical laboratory sample collections.  
• While in clinic, patients will follow a standard diet for diabetics. 
 
Because poppy seeds can sometimes cause a positive result on the drugs of abuse test, subjects 
are advised to avoid eating poppy seeds or foods containing poppy seeds for at least 48 hours 
before the drug screen at the Screening Visit, Check-in, and Follow-up Visit. 
The subject’s food consumption will be recorded in the subject’s source documentation. 
3.5.6.4 
Patient Activity Restrictions 
The following subject activity restrictions apply: 
• Subjects are not to donate blood within the 6 weeks before Check-in. 
• Subjects are not to have received blood products within the 2 months before Check-in. 

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• Subjects are not to have undergone a surgical procedure (other than minor dermatologic 
procedures) during the 30 days before Check-in. 
• Subjects should refrain from making any major lifestyle changes (eg, changing his or her 
exercise pattern) from the time of signature of the ICF to the End of Trial Visit. 
• Female subjects are not breastfeeding. 
 
3.6 
STOPPING CRITERIA 
All dosing will be stopped if the Sponsor and Investigator determine that any of the following 
have occurred: 
• Drug-related SAEs in 2 or more patients (per causality and SAE definitions in the protocol)  
• An overall pattern of clinically significant AEs or an overall pattern of patient tolerability 
issues, which may appear minor in terms of an individual event but, in the opinion of the 
Sponsor or Investigator, collectively represents a safety concern 
 
Note: Safety and tolerability will be assessed daily and dosing may be discontinued or dose 
escalation may be cancelled on an individual patient basis. Patients who discontinue dosing or do 
not escalate will remain in the clinic for at least 24 hours after their final dose of study drug and 
will complete all Discharge day assessments. In addition, these patients will return to the clinic 
for their Follow-up and End of Trial Visits 14 (±2) and 28 (±3) days, respectively, after their 
final dose of study drug. 
3.7 
STUDY PROCEDURES 
3.7.1 
Informed Consent 
Informed consent procedures will comply with the Code of Federal Regulations (CFR) 21, 
Parts 50 and 312. 
The written ICF must be approved by the Institutional Review Board (IRB) for the purposes of 
obtaining and documenting consent. 
Before entry into the study, each patient will be provided with a written explanation of the study. 
It is the responsibility of the Investigator or appropriately trained health professional to give each 

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patient full and adequate information regarding the objectives and procedures of the study and 
the possible risks involved. Patients will then be given the opportunity to ask questions and the 
Investigator will be available to answer questions as needed. Patients will be informed of their 
right to withdraw from the study at any time without prejudice. After this explanation and before 
entering the study, the patient will voluntarily sign an ICF. The patient should receive a copy of 
the signed and dated ICF. The Investigator must retain each patient’s original signed ICF. 
If new information becomes available that may be relevant to the patient’s consent and 
willingness to participate in the study, the ICF will be revised. The revised ICF must be 
submitted to the IRB for review and approval prior to its use. 
3.7.2 
Medical History 
A complete medical history will be recorded at the Screening Visit. 
3.7.3 
Safety Assessments 
3.7.3.1 
Physical Examination 
A complete physical examination will be performed according to the Schedule of Events. The 
physical examination of each patient should include examination and assessment of the 
following: 
General appearance 
Lymph nodes 
Musculoskeletal system 
Cardiovascular system 
Neurologic status 
Nervous system 
Respiratory system 
Head, eyes, ears, nose, and throat 
Skin 
Abdomen/liver/spleen 
Neck 
Mental status 
 
Breast, genitourinary, and rectal examinations are optional and may be performed at the 
discretion of the Investigator. Any new, clinically significant abnormal findings from the 
physical examination will be reported as an AE. 
Height will only be recorded at the Screening Visit; weight will be recorded according to the 
Schedule of Events. 

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3.7.3.2 
Vital Signs 
Vital signs will be measured according to the Schedule of Events and documented on the eCRF. 
Vital sign measurements include oral temperature (°C), respiratory rate, and supine and standing 
BP and pulse. Respiratory rate will be taken after the patient has been seated for at least 
5 minutes. At the Screening Visit and at Check-in, the blood pressure assessments should be 
completed at medication trough level, i.e. prior to subjects taking their hypertensive medications. 
In addition, at the Screening Visit and at Check-in the supine BP measurements will be the 
average of 3 measurements obtained at 2-minutes intervals after the patient has been lying 
quietly for at least 5 minutes; for supine only BP and pulse measurements thereafter, patient must 
lie quietly for at least 5 minutes before measurements are taken. For supine and standing BP and 
pulse measurements, patient must lie quietly for at least 5 minutes before supine measurements 
are taken, then assume a sitting position for 1 minute, and finally assume a standing position for 
2 minutes before standing measurements are taken. All BP and pulse measurements should be 
taken in the arm not used for EndoPAT occlusion and before blood draws where applicable. 
3.7.3.3 
Electrocardiograms 
A 12-lead ECG will be performed according to the Schedule of Events and documented on the 
eCRF. Electrocardiograms should be obtained after the patient has been supine for at least 
5 minutes. (Note: if on initial ECG, QTcF is ≥ 450 msec for male patients or is ≥ 470 msec for 
female patients, the ECG will be repeated 2 more times, and the average of the 3 QTcF values 
will be used to determine the patient's eligibility.) 
3.7.3.4 
Clinical Laboratory Tests 
Blood and urine samples for clinical laboratory tests will be collected, preferably from the left 
arm, according to the laboratory study procedures at the days and times defined in the Schedule 
of Events. Patients must have fasted for at least 8 hours before sample collections. The clinical 
laboratory evaluations will include the serum chemistry, hematology, coagulation, and urinalysis 
panels and the additional tests presented in Table 2. 

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Table 2. 
Clinical Laboratory Tests 
Serum Chemistry Panel 
Hematology Panel (CBC) 
Complete Urinalysis  
Albumin 
Hematocrit 
Color and appearance 
Alkaline Phosphatase 
Hemoglobin 
pH and Specific Gravity 
ALT 
Platelet count 
Bilirubin 
AST 
MPV 
Glucose 
Bicarbonate 
RBC count 
Ketones 
BUN 
WBC count 
Leukocytes 
Calcium 
WBC differential 
Nitrates 
Chloride 
(% & absolute): 
Occult blood 
Cholesterol 
Basophils 
Protein 
Creatinine 
Eosinophils 
Urobilinogen 
GGT 
Lymphocytes 
Microscopic  
Glucose 
Monocytes 
Including bacteria, RBCs, WBCs 
HDL-c 
Neutrophils 
per HPF if dipstick is abnormal 
LDH 
RBC indices 
 
LDL-c (calculated) 
MCH 
Additional tests 
Magnesium 
MCHC 
Hemoglobin A1c 
Phosphorus 
MCV 
Fasting blood glucose 
Potassium 
RDW 
Serum insulin 
Sodium 
 
 
Total Bilirubin 
Coagulation Panel 
 
Total Protein 
aPTT 
 
Triglycerides 
Prothrombin time 
 
 Uric acid 
INR 
 
ALT = alanine aminotransferase; aPTT = activated partial thromboplastin time; AST = aspartate 
aminotransferase; BUN = blood urea nitrogen; CBC = complete blood count; GGT = gamma glutamyl 
transferase; HPF = high power field; INR = International Normalized Ratio; LDH = lactate dehydrogenase; 
MCH = mean corpuscular hemoglobin; MCHC = mean corpuscular hemoglobin concentration; MCV = mean 
corpuscular volume; MPV = mean platelet volume; RBC = red blood cell; RDW = red blood cell distribution 
width; WBC = white blood cell.  
 
For female patients, a negative serum pregnancy test must be documented at the Screening Visit, 
at Check-in with results available before dosing, and at the End of Trial Visit; a negative urine 
pregnancy test must be documented at the Follow-up Visit before nitroglycerin dosing. In the 
event of a positive pregnancy test, the test will be repeated. If pregnancy is confirmed, see 
Section 3.7.3.8. 
At the Screening Visit, blood will be collected for a hepatitis panel (including hepatitis B surface 
antigen [HBsAg] and anti- hepatitis C virus [HCV]) and human immunodeficiency virus (HIV) 
antibody screen. 

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A urine drug screen for selected drugs of abuse and an alcohol breathalyzer screen will be 
performed at the Screening Visit, Check-in, and the Follow-up Visit. Patients will be screened 
for the following drugs of abuse: 
Amphetamines 
Cocaine 
Opiates 
Barbiturates 
Cotinine 
Phencyclidine (PCP) 
Benzodiazepines 
Marijuana 
Propoxyphene 
 
3.7.3.5 
Adverse Events  
All patients will be monitored for AEs throughout the study. All AEs will be recorded in 
accordance with the procedures outlined in this section. 
An AE is any untoward medical occurrence in a patient or clinical investigation subject 
administered a pharmaceutical product and which does not necessarily have to have a causal 
relationship with this treatment.  
An AE, therefore, can be any unfavorable and unintended sign (including an abnormal laboratory 
finding, for example), symptom, or disease temporally associated with the use of a medicinal 
product, whether or not considered related to the medicinal product. 
An AE includes, but is not limited to, the following: 
• Any unfavorable changes in general condition 
• Any clinically significant worsening of a preexisting condition 
• Any intercurrent diseases and accidents 
 
Note: A procedure is not an AE, but the reason for a procedure may be an AE. 

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3.7.3.5.1 
Causality Assessment 
For all AEs, the Investigator must provide an assessment of causal relationship to study drug. 
The causality assessment must be recorded in the patient’s source documentation and on the AE 
page of the subject’s eCRF. Causal relationship must be assessed according to the following: 
Related:   
An event where there is a reasonable possibility of a causal relationship between 
the event and the study drug 
Unrelated:   Any other event 
3.7.3.5.2 
Severity Assessment 
The Investigator will provide an assessment of the severity of each AE by recording a severity 
rating in the patient’s source documentation and on the AE page of the patient’s eCRF. Severity, 
which is a description of the intensity of manifestation of the AE, is distinct from seriousness, 
which implies a patient outcome or AE-required treatment measure associated with a threat to 
life or functionality. Severity will be assessed according to the following scale: 
Mild: 
A type of AE that is usually transient and may require only minimal treatment or 
therapeutic intervention. The event does not generally interfere with usual 
activities of daily living. 
Moderate: 
A type of AE that is usually alleviated with additional specific therapeutic 
intervention. The event interferes with usual activities of daily living, causing 
discomfort but poses no significant or permanent risk of harm to the research 
participant. 
Severe: 
A type of AE that interrupts usual activities of daily living, or significantly affects 
clinical status, or may require intensive therapeutic intervention. 
 
3.7.3.6 
Serious Adverse Events 
An SAE is defined as any AE occurring at any dose that results in any of the following 
outcomes: 
• Death 
• Life-threatening:  the patient was at immediate risk of death from the reaction as it occurred 
(ie, it does not include a reaction that hypothetically might have caused death if it had 
occurred in a more severe form) 

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• Hospitalization or prolongation of existing hospitalization 
• Persistent or significant disability/incapacity:  a substantial disruption of a person’s ability to 
conduct normal daily functions 
• Congenital anomaly/birth defect 
• Important medical events:  events that may not result in death, be life threatening, or require 
hospitalization. Such an event may be considered serious when, based on appropriate medical 
judgment, it may jeopardize the subject and may require medical or surgical intervention to 
prevent 1 of the outcomes listed in this definition. Examples of such medical events include 
allergic bronchospasm requiring intensive treatment in an emergency department or at home, 
blood dyscrasias or convulsions that do not result in inpatient hospitalization, or the 
development of drug dependency or drug abuse. 
 
Emergency room visits that do not result in admission to the hospital should be evaluated for 1 of 
the other serious outcomes (eg, life-threatening, other serious [medically important] event). 
3.7.3.7 
Recording Adverse Events 
Adverse events will be collected and recorded from the time the patient signs the ICF at the 
Screening Visit through the End of Trial Visit. All AEs, regardless of the assumption of a causal 
relationship with study procedures or study medication, must be recorded in the patient’s source 
documentation and subsequently on the appropriate AE page of the patient’s eCRF. This record 
includes AEs the patient reports spontaneously, those observed by the Investigator, and those 
elicited by the Investigator in response to open-ended questions during the study, such as “Have 
you had any health problems since your last visit?” 
For every AE, the Investigator must 
• Provide an assessment of the severity, causal relationship to the study medication, and 
seriousness of the event 
• Document all actions taken with regard to the study medication (ie, no action taken, 
treatment temporarily interrupted, or treatment discontinued)  
• Detail any other treatment measures taken for the AE, including concomitant medications 
and/or procedures 
 

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Pretreatment AEs will be collected from the time the patient signs the ICF until the patient 
receives study drug. Pretreatment AEs will be captured in the patient’s source documentation but 
will only be entered for patients who receive study drug on the AE page of the patient’s eCRF. 
Laboratory abnormalities and changes in vital signs, physical examination findings, and 12-lead 
ECG parameters should be considered AEs and reported on the AE page of the patient’s eCRF if 
the Investigator considers them clinically significant and/or they necessitate intervention. 
Any medical condition that is present when a patient is screened and does not worsen in severity 
and/or frequency should be reported as Medical History and not as an AE. However, if the 
condition does deteriorate in severity and/or frequency at any time during the study, it should be 
reported as an AE. 
3.7.3.8 
Reporting Serious Adverse Events 
An AE that meets any of the serious criteria must be reported to Ironwood within 24 hours from 
the time that site personnel first learn of the event, using the SAE Report form provided for the 
study. Regardless of causality, all SAEs must be reported and will be collected and recorded 
from the time the subject signs ICF at the Screening Visit until the End of Trial Visit. All SAEs 
must also be recorded in the subject’s source documentation and on the AE page of the subject’s 
eCRF. 
The initial report should include at least the following information: 
• Patient identification number 
• Description and onset of the event 
• Serious criteria 
• Causality assessment to study drug 
 
Special Situation:  Exposure to Study Drug during Pregnancy 
In the event that a pregnancy occurs in a patient, the study drug must be stopped at once, and 
study personnel must report the pregnancy as soon as possible (within 24 hours after notification) 
on the pregnancy notification form provided for this study. The study personnel must follow the 

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pregnancy until the end and report the pregnancy outcome on the pregnancy outcome form 
provided for this study. If the pregnancy is associated with an SAE (eg, if the mother is 
hospitalized), a separate SAE form must be completed. 
All relevant SAE or pregnancy information should be emailed to Ironwood Drug Safety and 
Pharmacovigilance. 
All SAE Report Forms should be emailed to: 
 
Clinical Drug Safety & Pharmacovigilance 
Ironwood Pharmaceuticals, Inc. 
 
 
 
If follow-up is obtained, or requested by Ironwood, the additional information should be emailed 
on an SAE Report Form to Ironwood, in a timely manner according to the procedures outlined 
above. Copies of discharge summaries, consultant reports, autopsy reports, and any other 
relevant documents may also be requested. 
Appropriate remedial measures should be taken by the Investigator using his/her best medical 
judgment to treat the SAE. These measures and the subject’s response to these measures should 
be recorded. All SAEs regardless of relationship to study drug will be followed by the 
Investigator until satisfactory resolution, until the Investigator deems the SAE to be chronic or 
stable, or until the subject is lost to follow-up. Clinical, laboratory, and diagnostic measures 
should be employed by the Investigator as needed to adequately determine the etiology of the 
event. 
The Investigator will be responsible for reporting all SAEs to the IRB. Ironwood will be 
responsible for reporting to the regulatory authorities. 
3.7.4 
Pharmacodynamic Assessments 
Hemodynamic and endothelial function assessments will be used to determine the PD parameters 
for PD analyses. 

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3.7.4.1 
Hemodynamics 
Blood pressure and pulse measurements for PD analyses will include supine and standing pulse 
and BP (for calculation of orthostatic pulse rate and BP) and ABPM collected according to the 
Schedule of Events. The left arm will be used for BP measurements. Hemodynamic effects will 
be assessed using the following parameters: 
• From supine and standing measurements – change from baseline (placebo cycle) in systolic 
and diastolic BP and pulse rate measurements 
• From orthostatic (standing minus supine) measurements – orthostatic change in systolic and 
diastolic BP and pulse rate 
• From ambulatory monitoring – change from baseline (placebo cycle) in 4-hour, 30-minute, 
and daytime (awake) averages of systolic and diastolic BP, mean arterial pressure, and pulse 
rate 
3.7.4.2 
Endothelial Function 
Endothelial function in the finger will be measured according to the Schedule of Events using the 
noninvasive EndoPAT device. Assessments will occur at least 3 hours after any caffeine-
containing foods or beverages and at least 1 hour after administration of any allow concomitant 
medications. All measurements will be performed in a quiet, dimly lit, temperature-controlled 
(22–24°C) room to reduce vascular tone fluctuation. The procedure will begin after the patient 
has had the opportunity to void and has been resting quietly for 15 minutes. The right arm will be 
used for occlusion and finger measurements. Endothelial function will be assessed using the RHI 
parameter.  
The EndoPAT procedure requires data entry of height, weight, and blood pressure assessments in 
the EndoPAT software as follows. The Screening height will be used for all EndoPAT 
assessments. The weight assessments obtained at Screening, Check-in and Follow-up will be 
used for the Screening, Check-in, and Follow-up EndoPAT assessments respectively. The weight 
assessment from Day 1 of each cycle will be used for the EndoPAT completed on Day 3 of each 
dosing cycle. Blood pressure is required as part of the EndoPAT procedure to determine the 
range of occlusion pressure necessary to complete the procedure. Therefore, as part of the 
EndoPAT procedure, BP assessments will be taken at least 15 minutes prior to starting the 
EndoPAT recording. If multiple EndoPAT procedures are completed on the same day, just one 

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3.8 
STUDY ACTIVITIES 
3.8.1 
Screening Period (Days –28 to Day -2) 
3.8.1.1 
Screening Visit (Days –28 to Day -2) 
• Signing of ICF 
• Review of inclusion and exclusion criteria 
• Demographics and medical history 
• Prior medications (all medicines taken during the 30 days before the Screening Visit) 
• Weight and height 
• Physical examination 
• Respiratory rate and oral temperature 
• 12-lead ECG 
• EndoPAT assessment (before BP measurements and blood sample collection) 
• Supine BP (average of 3 measurements) and pulse  
• Supine-to-standing (orthostatic) pulse and BP  
• Collection of blood and urine samples for clinical laboratory test, including: 
- 
Clinical chemistry 
- 
Hematology (CBC) 
- 
Coagulation 
- 
Urinalysis 
- 
Serum pregnancy test for all females (must be confirmed negative) 
- 
Hemoglobin A1c 
- 
Fasting blood glucose 
- 
Serum insulin 
- 
Drug screen 
- 
HBsAg, HCV, and HIV screen 
• Alcohol breathalyzer  
• AE evaluation 
Note: Screening Visit assessments may take place over more than 1 day.  
Patients may be rescreened should they discontinue in the Screening Period due to visit window deviations or other 
administrative reasons. 
 

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3.8.2 
Clinic Period (Days -1 to Day 19) 
Patients will be confined to the clinic from Check in on Day -1 until Discharge on Day 19. 
3.8.2.1 
Check-in (Day -1) 
• Review of inclusion and exclusion criteria 
• Weight  
• Physical examination 
• Respiratory rate and oral temperature  
• Prior (since the Screening Visit) and concomitant medications * 
• EndoPAT assessment * 
• Supine BP* (average of 3 measurements) and pulse 
• 12-lead ECG 
• Collection of blood and urine samples for clinical laboratory test, including: 
- 
Clinical chemistry 
- 
Hematology (CBC) 
- 
Coagulation 
- 
Urinalysis 
- 
Serum pregnancy test for all females (must be confirmed negative) * 
- 
Hemoglobin A1c * 
- 
Fasting blood glucose * 
- 
Serum insulin 
- 
Drug screen * 
 
 
• Alcohol breathalyzer * 
• AE evaluation 
* must meet Eligibility Criteria at Check-in 
 

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3.8.2.4 
Third Day of Each 3-day Dosing Cycle (Days 3, 6, 9, 12, 15, 18) 
• EndoPAT assessment predose (≤ 1 hour) and at 4 and 12 hours (± 15 minutes) postdose 
• Supine pulse and BP predose (≤ 30 minutes) and at 1, 2, and 8 hours (± 10 minutes) postdose 
• Administration of study drug and allowed concomitant medications 
• Breakfast (≤ 30 minutes) after study drug administration 
• AE evaluation 
• Concomitant medication recording 
 
3.8.2.5 
Discharge (Day 19) 
• Weight  
• Supine-to-standing (orthostatic) pulse and BP at 24 hours (± 15 minutes) postdose 
• Physical examination 
• 12-lead ECG 
• Respiratory rate and oral temperature  
• Collection of blood and urine samples for clinical laboratory test, including: 
- 
PK blood sample at 24 hours (± 15 minutes) postdose 
 
  
- 
Clinical chemistry 
- 
Hematology (CBC) 
- 
Coagulation 
- 
Urinalysis 
- 
Hemoglobin A1c 
- 
Fasting blood glucose  
- 
Serum insulin 
• AE evaluation 
• Concomitant medications 
• Discharge from the clinic 
 

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3.9.3 
Statistical Methods 
3.9.3.1 
General Considerations 
Continuous variables will be summarized using the mean, standard deviation, minimum, median, 
interquartile range, and maximum. Categorical variables will be summarized using the number 
and percentage of subjects in each category. Data summaries will be presented by treatment 
group. 
Inferential statistics, if calculated, will only be used for descriptive purposes. 
3.9.3.2 
Patient Disposition, Demographics, and Baseline Characteristics 
The number and percentage of patients in each of the 3 analysis populations (Safety, PK, and 
PD) who completed the study or discontinued early, as well as the reasons for discontinuation, 
will be presented.  
Subject demographics (age, sex, race, ethnicity, weight, height, BMI, and other baseline 
characteristics) will be summarized for the Safety Population. 
3.9.3.3 
Pharmacodynamic Analyses 
3.9.3.3.1 
Hemodynamics 
Descriptive statistics including 95% confidence intervals will be presented for the following 
hemodynamic parameters by treatment group: 
• Change from study baseline (Day -1 assessment) and time-matched baseline (placebo cycle 
assessments) in supine pulse, systolic BP, and diastolic BP  
• Orthostatic change in pulse, systolic BP, and diastolic BP. An orthostatic measurement is 
obtained by subtracting the supine measurement from the standing measurement 
• Change from time-matched baseline (placebo cycle assessments) in 4-hour, 30-minute, and 
daytime averages of systolic BP, diastolic BP, mean arterial pressure and pulse 
measurements from ambulatory BP monitoring 
• Change from pre-nitroglycerin dose assessment to post-nitroglycerin dose assessment in 
supine pulse, systolic BP, and diastolic BP 

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3.9.3.3.2 
Endothelial Function 
Descriptive statistics, including 95% confidence intervals, will be presented for the following 
endothelial function parameters by treatment group: 
• Change from study baseline (Day -1 assessment) in RHI  
• Change from time-matched baseline (placebo cycle assessments) in RHI 
• Change from pre-nitroglycerin dose assessment of RHI to the post-nitroglycerin dose 
assessment on the Follow-up Visit 
 
3.9.3.3.3 
Platelet Function Assessment 
Descriptive statistics will be presented for the following platelet function assessment parameters 
by treatment group for each postdose assessment: 
• Change from baseline in platelet function assessments (based on PFA-100) 
 
3.9.3.4 
Safety Analyses 
3.9.3.4.1 
Adverse Events 
Adverse events will be coded using the latest version of Medical Dictionary for Regulatory 
Activities (MedDRA) available at the start of the study. Treatment-emergent adverse events 
(TEAEs) are those AEs that started or worsened in severity after the administration of study 
drug. TEAEs will be summarized by system organ class (SOC) and preferred term (PT) for each 
treatment group. In addition, listings of severe TEAEs, drug-related TEAEs, SAEs, AEs leading 
to study discontinuation, and AEs leading to death (if any) will be provided. 
3.9.3.4.2 
Vital signs, ECGs, Clinical Laboratory Tests 
Vital signs, 12-lead ECGs, clinical laboratory evaluations at each assessment timepoint and the 
change from study baseline (Day -1) at each postdose timepoint will be summarized by treatment 
group. 

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3.9.3.5 
Pharmacokinetic Analyses 
Plasma concentration values of IW-1973 will be summarized for each assessment timepoint by 
treatment group and mean plasma concentrations will be plotted over time for each dose level. 
If systemic levels of IW-1973 are detectable, the following PK parameters will be calculated, 
when appropriate: 
• AUCtau:  Area under the plasma concentration time curve during a dosing interval (tau) 
• Cmax:  Maximum observed plasma concentration, occurring at Tmax 
• Ctrough:  Trough plasma concentration observed at the end of a dosing interval (collected 
before the next administration) 
• t1/2:  Apparent terminal phase half-life 
• Tmax:  Time of maximum observed plasma concentration 
 
The PK parameters will be summarized for each dose level. 
3.9.3.6 
Interim Analysis 
There are no interim analyses planned for this study. 
3.9.3.7 
Computer Methods 
Statistical analyses will be performed using Statistical Analysis System (SAS®), version 9.3 (or 
newer). 
3.10 
CHANGES IN THE CONDUCT OF THE STUDY OR PLANNED 
ANALYSES 
Any amendment to this protocol will be provided to the Investigator in writing by Ironwood or 
its designee. Prior to implementation, any protocol amendment regarding reportable deviations 
(as defined by the IRB) must be approved by the IRB and the signature page must be signed by 
the Investigator and received by Ironwood or its designee, with the following exception: If the 
protocol is amended to eliminate or reduce the risk to patients, the amendment may be 
implemented before IRB review and approval. However, the IRB must be informed in writing of 
such an amendment, and approval must be obtained within reasonable time limits. 

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Deviating from the protocol is permitted only if absolutely necessary for the safety of the 
patients and must immediately be reported to Ironwood or its designee. 

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4. 
ETHICAL CONSIDERATIONS 
4.1 
INSTITUTIONAL REVIEW BOARD 
Prior to the study onset, the protocol, any protocol amendments, ICFs, advertisements to be used 
for patient recruitment, and any other written information regarding this study to be provided to a 
patient or patient’s legal guardian must be approved by the IRB. 
All IRB approvals must be dated and signed by the IRB Chairman or his or her designee and 
must identify the IRB by name and address, the clinical protocol by title and/or protocol number, 
and the date upon which approval or favorable opinion was granted for the clinical research. 
Copies of IRB approvals should be forwarded to Ironwood. All correspondence with the IRB 
should be maintained in the Investigator File. 
No drug will be released to the site to dose a patient until written IRB approval has been received 
by Ironwood. 
The Investigator is responsible for obtaining continuing review of the clinical research at least 
annually or more often if specified by the IRB. The Investigator must supply Ironwood with 
written documentation of the approval of the continued clinical research. 
The IRB must be constituted in accordance with Federal and International Conference on 
Harmonization (ICH) Good Clinical Practice (GCP) guidelines and any relevant and applicable 
local regulations. 
Major changes in this research activity, except those to remove an apparent immediate hazard to 
the patient, must be reviewed and approved by Ironwood and by the IRB that approved the study. 
Amendments to the protocol must be submitted in writing to the Investigator’s IRB for approval 
prior to patients being enrolled into the amended protocol. 
4.2 
PATIENT INFORMATION AND INFORMED CONSENT 
Informed consent procedures will comply with the Code of Federal Regulations (CFR) 21, 
Parts 50 and 312. 

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The written ICF must be approved by the IRB for the purposes of obtaining and documenting 
consent. 
Before entry into the study, each patient will be provided with a written explanation of the study. 
It is the responsibility of the Investigator or appropriately trained health professional to give each 
patient full and adequate information regarding the objectives and procedures of the study and 
the possible risks involved. Patients will then be given the opportunity to ask questions and the 
Investigator will be available to answer questions as needed. Patients will be informed of their 
right to withdraw from the study at any time without prejudice. After this explanation and before 
entering the study, the patient will voluntarily sign an ICF. The patient should receive a copy of 
the signed and dated ICF. The Investigator must retain each patient’s original signed ICF. 
If new information becomes available that may be relevant to the patient’s consent and 
willingness to participate in the study, the ICF will be revised. The revised ICF must be 
submitted to the IRB for review and approval prior to its use. 

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5. 
INVESTIGATORS AND STUDY ADMINISTRATIVE 
STRUCTURE 
This study will be performed at 1 study center in the US. The Investigator at the study center will 
be responsible for ensuring that the study is conducted according to the signed Clinical Trial 
Agreement, the protocol, IRB requirements, and ICH GCP guidelines. 
The Investigator will be responsible for the oversight of the site’s conduct of the study, which 
will consist of completing all protocol assessments, maintaining the study file and the patient 
records, drug accountability, corresponding with the IRB, and completing the eCRF. 
5.1 
GENERATION OF STUDY RECORDS 
Ironwood or its designated representative will conduct a study center visit to verify the 
qualifications of each Investigator, inspect study center facilities, and inform the Investigator of 
responsibilities and procedures for ensuring adequate and correct study documentation. 
The Investigator is required to prepare and maintain adequate and accurate case histories 
designed to record all observations and other data pertinent to the study for each study patient. 
All information recorded in the eCRFs for this study must be consistent with the patient’s source 
documentation. 
During the course of the study, the Clinical Site Monitor will make study center visits to review 
protocol compliance, compare eCRFs and individual patient’s medical records, assess drug 
accountability (in a blinded manner), and ensure that the study is being conducted according to 
pertinent regulatory requirements. All eCRFs will be verified with source documentation. The 
review of medical records will be performed in a manner that ensures patient confidentiality is 
maintained. 
The Clinical Site Monitor will discuss instances of missing or uninterpretable data with the 
Investigator for resolution. Any changes to the study data will be made to the eCRF and 
documented via an electronic audit trail associated with the affected eCRF. 

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5.2 
DATA QUALITY ASSURANCE 
Ironwood performs quality control and assurance checks on all of its clinical studies. Section 5.4 
provides details regarding study monitoring procedures. 
The study may be subject to audit by Ironwood, its representatives, or regulatory authorities. In 
the event of an audit, the Investigator must agree to allow Ironwood, representatives of 
Ironwood, or the FDA or other regulatory agencies access to all study records. 
5.3 
ELECTRONIC CASE REPORT FORMS AND DATA MANAGEMENT 
All data relating to the study will be recorded in the patient’s source documentation and eCRF to 
be provided by Ironwood or designee via the electronic data capture (EDC) system. Source 
documentation supporting the eCRF data should indicate the patient’s participation in the study 
and should document the dates and details of study procedures, AEs, all observations, and patient 
status. The Investigator is responsible for verifying that all data entries on the eCRFs are accurate 
and correct and ensuring that all data are entered in a timely manner, as soon as possible after the 
information is collected. An explanation should be provided for any missing data. The 
Investigator must provide through the EDC system his or her formal approval of all the 
information in the eCRFs and changes to the eCRFs to endorse the final submitted data for each 
patient. 
Ironwood will retain the final eCRF data and corresponding audit trails. A copy of the final 
archival eCRF in the form of a compact disc or other electronic media will be placed in the 
Investigator’s study file. 
A record of screen failures and pretreatment failures will be maintained for patients who do not 
qualify for enrollment, including the reason for the failure. 
5.4 
STUDY MONITORING 
Ironwood performs quality control and assurance checks on all of its clinical studies. Before any 
patients are enrolled in the study, a representative of Ironwood or its authorized designee will 
meet with the Investigator and his/her staff to review relevant and important study-related 
information including, but not limited to, the protocol, the Investigator’s Brochure, the eCRFs 

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and instructions for their completion using the EDC system, the procedure for obtaining 
informed consent, and the procedure for reporting AEs and SAEs. 
An Ironwood representative, the Clinical Site Monitor, will monitor the progress and conduct of 
the study by periodically conducting monitoring visits and by frequent communications 
(telephone, e-mail, letter, and fax) with the study centers. The site monitor will ensure that the 
study is conducted according to the protocol and regulatory requirements. During monitoring 
visits, the information recorded on the eCRFs will be verified against source documents. Upon 
request of the monitor, auditor, IRB, or regulatory authority, the Investigator should make all 
requested study-related records available for direct access. 
All aspects of the study will be carefully monitored by Ironwood or its designee for compliance 
with applicable government regulations with respect to GCP and current standard operating 
procedures. 

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6. 
STUDY SPONSORSHIP 
6.1 
INVESTIGATOR AND STUDY TERMINATION 
Ironwood may terminate Investigator participation at any institution for any reason. If 
participation is ended at the site by either Ironwood or the Investigator, the Investigator must 
• Return all study medications and any study materials to Ironwood 
• In cases where the Investigator opts to self-terminate, provide a written statement describing 
why the study was terminated prematurely 
 
Ironwood may terminate the study in its entirety or at a specific center at any time for any 
reason, including but not limited to the following: 
• Failure to enroll patients 
• Protocol violations 
• Inaccurate or incomplete data 
• Unsafe or unethical practice 
• Questionable safety of the study medication 
• Administrative decision 
 
6.2 
REPORTING AND PUBLICATION 
All data generated in this study will be the property of Ironwood. An integrated clinical and 
statistical report will be prepared at the completion of the study. 
Publication of the results by the Investigator will be subject to mutual agreement between the 
Investigator and Ironwood. 

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7. 
INVESTIGATOR OBLIGATIONS 
7.1 
DOCUMENTATION 
The Investigator must provide the Sponsor with the following documents BEFORE the 
enrollment of any subjects, in accordance with ICH E6 (Note: Ironwood must be notified if there 
are any changes to these documents): 
1. Completed and signed Form FDA 1572 (Statement of Investigator) including all sub-
investigators involved in the study 
2. Financial disclosure form(s) for the Investigator and all sub-investigators listed on Form 
FDA 1572 
3. Current, signed curricula vitae of the Investigator and all sub-investigators 
4. Copy of current medical license of the Investigator and all sub-investigators (as applicable) 
5. Copy of the IRB approval letter for the protocol and ICF 
6. Copy of the IRB-approved ICF to be used 
7. Copy of the IRB approval of recruitment advertising (if applicable) 
8. A list of IRB members and their qualifications, and a description of the committee’s working 
procedures 
9. Protocol Approval Page signed by the Investigator 
10. Fully executed Clinical Trial Agreement 
11. Written document containing the name, location, certification number, and date of 
certification of the local laboratory to be used for laboratory assays and those of other 
facilities conducting tests 
12. List of normal laboratory values and units of measurements for all laboratory tests required 
by the protocol. This list is required for each local laboratory to be used during the study. 
 
During the study, the Investigator must maintain the following essential/administrative 
documents related to the study: 
1. Copy of the signed Protocol Signature Page 
2. Copy of financial disclosure form(s) for the Investigator and all sub-investigators (as 
applicable) if updated 
3. Curricula vitae of any new Investigator(s) and/or sub-investigators involved in the study 
4. Copy of current medical license of the Investigator and all sub-investigators (as applicable) if 
updated 

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5. Copy of the signed Form FDA 1572 
6. IRB Approval Notification for the following: 
a. Protocol 
b. Informed consent document 
c. Recruitment advertising (if applicable) 
d. Amendment(s) (if applicable) 
e. Annual review of the protocol and the informed consent document 
f. SAEs 
g. Study closure 
7. SAE Reports 
8. Drug Inventory Forms (drug receipts, drug dispensing, and inventory forms) 
9. Name and address of local or central laboratory, list of normal laboratory values and units of 
measurement, as well as laboratory certification or hospital accreditation 
10. Updates of medical/laboratory/technical procedures/tests: 
a. Normal value(s)/ranges(s) 
b. Certification 
c. Accreditation 
d. Established quality control and/or external quality assessment 
e. Other validation (where required) 
11. Record of retained body fluids/tissue samples (if any) 
12. Correspondence with Sponsor 
13. Written assurance of continuing approval (at least annually) as well as a copy of the annual 
progress report submitted to the IRB must also be provided to the Sponsor. Any changes in 
this study or unanticipated problems involving risks to the patients must be reported 
promptly to the IRB. An Investigator must not make any changes in a study without IRB and 
Sponsor approval, except when necessary to eliminate apparent immediate hazards to the 
subjects. All protocol amendments must be submitted to the IRB and approved. 
14. Responsibility Log 
15. Other logs (eg, screening, enrollment) 
16. Signed ICFs 
17. Patient source documentation 
18. eCRFs 
19. Audit certificate(s), if applicable 
 

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7.2 
PERFORMANCE 
The Investigator must demonstrate reasonable efforts to obtain qualified patients for the study. 
The Sponsor may terminate the study with any Investigator for any reason, including, but not 
limited to, Investigator nonperformance or Investigator noncompliance. 
7.3 
ACCOUNTABILITY 
Ironwood requires accountability of all study drug received and administered by the Study 
Center. Required records of drug disposition are to include logs or dispensing-records capturing, 
but not limited to, the date study drug was received, date(s) individual dosing units were 
prepared and labeled, date administered, quantity administered, and the subject to whom study 
drug was administered. At the end of the study, a complete reconciliation of the study drug 
supplies will be performed. All unused and reconciled drug supplies will be destroyed according 
to standard institutional policy or per written instruction from Ironwood should an alternate 
disposition be requested. No study drug is to be destroyed without prior written permission of 
Ironwood. A copy of the Certificate of Destruction or equivalent shall be provided to Ironwood 
once available. 
7.4 
RETENTION AND REVIEW OF RECORDS 
Records and documents pertaining to the conduct of this study, including eCRFs, source 
documents, ICFs, laboratory test results, and medication inventory records, must be retained by 
the Investigator in accordance with locally applicable regulatory requirements; and, in any event, 
for a minimum period of 5 years.  
No study records shall be destroyed without notifying Sponsor and giving Sponsor the 
opportunity to take such study records or authorizing in writing the destruction of records after 
the required retention period. 
If the Investigator retires, relocates, or otherwise withdraws from the responsibility of keeping 
the study records, custody must be transferred to another person (Ironwood, IRB, or other 
Investigator) who will accept the responsibility. Ironwood must be notified of and agree to the 
change. 

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7.5 
PATIENT CONFIDENTIALITY 
All data collected in the context of this study will be stored and evaluated in such a way as to 
guarantee patient confidentiality in accordance with the legal stipulations applying to 
confidentiality of data. All patient records will be identified only by initials and patient 
identification (PID) number. Patient names are not to be transmitted to Ironwood or its 
authorized designee. The Investigator will keep a Master Patient List on which the PID number 
and the full name, address, and telephone number of each patient is listed. 

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8. 
REFERENCE LIST 
1. Deanfield JE, Halcox JP, Rabelink TJ. Endothelial function and dysfunction: testing and 
clinical relevance. Circulation 2007;115(10):1285-95. 
2. Munzel T. [Endothelial dysfunction: pathophysiology, diagnosis and prognosis]. Dtsch Med 
Wochenschr 2008 Nov;133(47):2465-70. 
3. van den Oever IA, Raterman HG, Nurmohamed MT, Simsek S. Endothelial dysfunction, 
inflammation, and apoptosis in diabetes mellitus. Mediators of inflammation 
2010;2010:792393. 
4. Davignon J, Ganz P. Role of endothelial dysfunction in atherosclerosis. Circulation 
2004;109(23 Suppl 1):III27-III32. 
5. Vanhoutte PM, Vanhoutte PM, Shimokawa H, Feletou M, Tang EH, Shimokawa H, et al. 
Endothelial Dysfunction and Vascular Disease - A Thirthieth Anniversary Update. Acta 
Physiologica 2015;n/a. 
6. Corson MA, James NL, Latta SE, Nerem RM, Berk BC, Harrison DG. Phosphorylation of 
endothelial nitric oxide synthase in response to fluid shear stress. Circulation research 
1996;79(5):984-91. 
7. Denninger JW, Marletta MA. Guanylate cyclase and the .NO/cGMP signaling pathway. 
Biochimica et biophysica acta 1999;1411(2-3):334-50. 
8. Aversa A. Chronic administration of Sildenafil improves markers of endothelial function in 
men with Type 2 diabetes. Diabetic Medicine 2008;25(1):37-44. 
9. Brown KE, Dhaun N, Goddard J, Webb DJ. Potential therapeutic role of phosphodiesterase 
type 5 inhibition in hypertension and chronic kidney disease. Hypertension 2014;63(1):5-11. 
10. Chester M, Seedorf G, Tourneux P, Gien J, Tseng N, Grover T, et al. Cinaciguat, a soluble 
guanylate cyclase activator, augments cGMP after oxidative stress and causes pulmonary 
vasodilation in neonatal pulmonary hypertension. American journal of physiology Lung 
cellular and molecular physiology 2011;301(5):L755-L764. 
11. Stasch JP, Pacher P, Evgenov OV. Soluble guanylate cyclase as an emerging therapeutic 
target in cardiopulmonary disease. Circulation 2011;123:2263-73. 
12. Nossaman BD, Kadowitz PJ. Stimulators of soluble guanylyl cyclase: future clinical 
indications. The Ochsner journal 2013;13:147-56. 
13. Centers for Disease Control and Prevention. National Diabetes Statistics Report: Estimates of 
Diabetes and Its Burden in the United States, 2014. Atlanta, GA: US Department of Health 
and Human Services; 2014.  

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14. Iglay K, Hannachi H, Joseph HP, Xu J, Li X, Engel SS, et al. Prevalence and co-prevalence 
of comorbidities among patients with type 2 diabetes mellitus. Current medical research and 
opinion 2016;32(7):1243-52. 
15. Arauz-Pacheco C, Parrott MA, Raskin P. Hypertension management in adults with diabetes. 
Diabetes care 2004;27 Suppl 1:S65-S67. 
16. Rahman S, Rahman T, Ismail AA, Rashid AR. Diabetes-associated macrovasculopathy: 
pathophysiology and pathogenesis. Diabetes, obesity & metabolism 2007;9(6):767-80. 
 

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9. 
SPONSOR SIGNATURE 
Study Title: 
An Open-label, Phase 2a Trial to Evaluate the Effect of Escalating 
Doses of IW-1973 on Tolerability, Endothelial Function, and 
Hemodynamics in Patients with Stable Type 2 Diabetes and 
Hypertension 
Study Number: 
C1973-201 
 
This clinical study protocol was subject to critical review and has been approved by the sponsor.  
 
Signed: 
 
 
Date:  
 
 
Senior Director, Clinical Research 
 
Ironwood Pharmaceuticals, Inc. 
 
 

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10. 
INVESTIGATOR SIGNATURE 
Study Title: 
An Open-label, Phase 2a Trial to Evaluate the Effect of Escalating 
Doses of IW-1973 on Tolerability, Endothelial Function, and 
Hemodynamics in Patients with Stable Type 2 Diabetes and 
Hypertension 
Study Number: 
C1973-201 
I have read the protocol described above. I agree to comply with all applicable regulations and to 
conduct the study as described in the protocol.  
 
 
Signed: 
 
 
Date:  
 
 
Senior Medical Director and Clinical Investigator 
ICON Early Phase Services, LLC  
8307 Gault Lane  
San Antonio, TX 78209