Conditions: Vascular System Injuries Concussion, Brain Post-Concussion Syndrome
Keywords: Sildenafil Concussion CBF CVR
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 22
Healthy volunteers: yes

Brief summary:
About 300,000 people are hospitalized for traumatic brain injury (TBI) each year. After TBI, secondary brain injury escalates due in part to heightened levels of oxidant injury, inflammation, and vascular injury. Traumatic cerebral vascular injury (TCVI) may begin almost immediately after the primary injury and evolve into chronic neurodegenerative conditions. TCVI is a very complex TBI endophenotype and microvascular injuries have been described in a plethora of animal and human TBI studies. These injuries consist of endothelial injury, disruption of the blood brain barrier (BBB), a reduction of capillary density, intravascular microthrombi, and white-matter degeneration. Recently, use of magnetic resonance imaging (MRI)-Blood Oxygen Level Dependent (BOLD) combined with hypercapnia (high spatial and temporal resolution) by our research group has proven to be more sensitive at measuring alterations of cerebral blood flow (CBF) in TBI subjects. The goal of the proposed research is to test the efficacy of Viagra® (sildenafil) at normalizing CBF and improving cognitive outcomes in people that have experienced a TBI. Sildenafil is a phosphodiesterase-5 (PDE-5) inhibitor that has previously been administered as a therapy for high blood pressure and erectile dysfunction. In people that have been affected by stroke-induce neurotrauma, sildenafil improved CBF and was found to be neuroprotective. With respect to chronic TBI, previous studies have demonstrated that sildenafil therapy potentiates cardiovascular reactivity (CVR) in areas of the brain with damaged endothelium. In this proposal, the investigators will test the hypothesis that sildenafil treatment in boxers/Mixed Martial Arts (MMA) fighters soon after concussion normalizes CBF, potentiates CVR, reduces post-concussion symptoms, and improves cognition.

Detailed description:
In this study, 100 professional boxers that experience a concussion will be enrolled, randomized to either placebo or sildenafil (60mg) drug treatment, and arterial spin labeling and BOLD-MRI with hypercapnia will used to assess CBF and CVR, respectively. Symptom reporting, blood biomarkers, and neuropsychological testing will also be conducted. The timepoints for this study are baseline (pre-fight), and once between days 1 and 3 and day 30 after injury.

Arms:
arm 1: If randomized to placebo, the participant will receive single (Group 1) or multiple (once-a-day for 14 days; Group 2) treatments. arm 2: If randomized to sildenafil (60mg), the participant will receive single (Group 1) or multiple (once-a-day for 14 days; Group 2) treatments.

Interventions: intervention 1: Sildenafil Citrate intervention 2: Placebo oral capsule
Intervention descriptions: intervention 1: Sildenafil 60mg once (Group 1) or daily for 2 weeks (Group 2) intervention 2: Placebo once (Group 1) or daily for 2 weeks (Group 2)

Protocol document:
Prot_SAP_000.pdf: 
 
 Title: Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 NCT number: NCT03598140 
Protocol Date: 1 March 2018, Version Number: 2.0 
 


STUDY PROTOCOL 
 
Title: Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
 
Protocol Identifying Number: UT-7529 
 
 
Principal Investigator(s): Kan Ding, M.D. 
 
 
Institution: UT Southwestern Medical Center 
 
 
IND/IDE Sponsor: Food and Drug Administration (IND# 134596) 
 
 
 
 
 
 
Version Number:  2.0 
 
1 March 2018 
 


ii 
 
Table of Contents 
LIST OF ABBREVIATIONS ..................................................................................................... 1-2 
STATEMENT OF COMPLIANCE ............................................................................................... 2 
PROTOCOL SUMMARY ......................................................................................................... 2-4 
SCHEMATIC OF STUDY DESIGN ............................................................................................ 4 
1 
KEY ROLES …………………………………………………………………………………….4-5 
2  
INTRODUCTION: BACKGROUND INFORMATION AND SCIENTIFIC RATIONALE ... 5-7  
2.1 
Background Information ....................................................................................... 5-6 
2.2 
Rationale .............................................................................................................. 6-7 
2.3 
Potential Risks and Benefits .................................................................................... 7 
2.3.1 
Known Potential Risks ............................................................................. 7 
2.3.2 
Known Potential Benefits ......................................................................... 7 
3 
OBJECTIVES AND PURPOSE ..................................................................................... 7-8 
4 
STUDY DESIGN AND ENDPOINTS ........................................................................... 8-11 
4.1 
Description of the Study Design .............................................................................. 8 
4.2.1 
Primary Endpoint ................................................................................ 9-11 
 
4.2.1.a  
 
Magnetic Resonance Imaging……………………………………9-10 
4.2.1.b  
 
TBI Neuropsychological Assessments ………………….……..10-11 
4.2.2 
Secondary Endpoints .............................................................................11 
5 
STUDY ENROLLMENT AND WITHDRAWAL ........................................................... 11-13 
5.1 
Participant Inclusion Criteria ...................................................................................11 
5.2 
Participant Exclusion Criteria ..................................................................................12 
5.3 
Strategies for Recruitment and Retention ...............................................................12 
5.4 
Participant Withdrawal or termination ............................................................... 12-13 
5.4.1 
Reasons for Withdrawal or Termination ..................................................12 
5.4.2 
Handling of Participant Withdrawals or termination ........................... 12-13 
5.5 
Premature Termination or Suspension of Study .....................................................13 
6 
STUDY AGENT ........................................................................................................ 13-15 
6.1 
Study Agent(s) and Control Description............................................................ 13-14 
6.1.1 
Acquisition ..............................................................................................13 
6.1.2 
Formulation, Appearance, Packaging, and Labeling ...............................13 
6.1.3 
Product Storage and Stability .................................................................13 
6.1.4 
Preparation ....................................................................................... 13-14 
6.1.5 
Dosing and Administration ......................................................................14 
6.1.6 
Route of Administration ..........................................................................14 
6.1.7 
Dose Adjustments/Modifications/Delays .................................................14 
6.1.8 
Duration of Therapy ................................................................................14 
6.1.9 
Tracking of Dose ....................................................................................14 
6.1.10 
Device Specific Considerations ..............................................................14 
6.2 
Study agent Accountability Procedures .......................................................... 14-145 
7 
STUDY PROCEDURES AND SCHEDULE ............................................................... 15-19 
7.1 
Study Procedures/Evaluations ...............................................................................15 
7.1.1 
Study specific procedures ......................................................................15 
7.1.2 
Standard of care study procedures .........................................................15 
7.2 
Laboratory Procedures/Evaluations .................................................................. 15-16 
7.2.1 
Clinical Laboratory Evaluations ........................................................ 15-16 


iii 
 
7.2.2 
Other Assays or Procedures ...................................................................16 
7.2.3 
Specimen Preparation, Handling, and Storage .......................................16 
7.2.4 
Specimen Shipment ...............................................................................16 
7.3 
Study Schedule ................................................................................................ 16-18 
7.3.1 
Screening ......................................................................................... 16-17 
7.3.2 
Enrollment/Baseline ...............................................................................17 
7.3.3 
Early Termination Visit ............................................................................18 
7.4 
Justification for Sensitive Procedures .....................................................................18 
7.5 
Concomitant Medications, Treatments, and Procedures ........................................18 
7.5.1 
Precautionary Medications, Treatments, and Procedures .......................18 
7.6 
Rescue Medications, Treatments, and Procedures .......................................... 18-19 
7.7 
Participant Access to Study Agent At Study Closure ..............................................19 
8 
ASSESSMENT OF SAFETY ..................................................................................... 19-24 
8.1 
Specification of Safety Parameters ................................................................... 19-20 
8.1.1 
Definition of Adverse Events (AE)...........................................................19 
8.1.2 
Definition of Serious Adverse Events (SAE) ...........................................19 
8.1.3 
Definition of Unanticipated Problems (UP) ........................................ 19-20 
8.2 
Adverse Events ................................................................................................ 20-23 
8.2.1 
Severity of Event ....................................................................................20 
8.2.2 
Expectedness ................................................................................... 20-23 
8.3 
Time Period and Frequency for Event Assessment and Follow-Up .................. 23-24 
8.4 
Reporting Procedures ............................................................................................24 
8.4.1 
Adverse Event Reporting ........................................................................24 
8.4.2 
Reporting of Pregnancy ..........................................................................24 
8.5 
Study Halting Rules ................................................................................................24 
8.6 
Safety Oversight .....................................................................................................24 
9 
CLINICAL MONITORING .......................................................................................... 25-26 
10 
STATISTICAL CONSIDERATIONS .......................................................................... 26-30 
10.1 
Statistical and Analytical Plans ......................................................................... 26-29 
10.2 
Measures to Minimize Bias............................................................................... 29-30 
10.2.1 
Enrollment/ Randomization/ Masking Procedures ............................ 29-30 
11 
SOURCE DOCUMENTS AND ACCESS TO SOURCE DATA/DOCUMENTS .................30 
12 
QUALITY ASSURANCE AND QUALITY CONTROL .......................................................30 
13 
ETHICS/PROTECTION OF HUMAN SUBJECTS…………………………………….…30-33 
13.1 
Ethical Standard ............................................................................................... 30-31 
13.2 
Institutional Review Board ......................................................................................31 
13.3 
Informed Consent Process .....................................................................................31 
13.3.1 
Consent/assent and Other Informational to  participants ........................31 
13.3.2 
Consent Procedures and Documentation ...............................................31 
13.4 
Participant and data Confidentiality .................................................................. 31-33 
13.4.1 
Research Use of Stored Human Samples,Specimens or Data ......... 32-33 
13.5 
Future Use of Stored Specimens............................................................................32 
14 
DATA HANDLING AND RECORD KEEPING ........................................................... 33-34 
14.1 
Data Collection and Management Responsibilities .................................................33 
14.2 
Study Records Retention .......................................................................................33 


iv 
 
14.3 
Protocol Deviations ................................................................................................33 
14.4 
Publication and Data Sharing Policy .......................................................................34 
15 
STUDY ADMINISTRATION ...................................................................................... 34-35 
15.1 
Study Leadership ...................................................................................................34 
16 
CONFLICT OF INTEREST POLICY ...............................................................................34 
17  
LITERATURE REFERENCES .................................................................................. 35-39 
 
 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
1 
LIST OF ABBREVIATIONS 
 
AE 
Adverse Event 
AIC 
Akaike Information Criterion 
ASL  
Arterial Spin Labeling 
BBB 
Blood Brain Barrier 
BHI 
Breath Holding Index 
BIC 
Bayesian Information Criterion 
BOLD (MRI 
sequence) 
Blood Oxygen Level Dependent 
BP 
Blood Pressure 
BSI  
Brief Symptom Inventory 
CBF 
Cerebral Blood Flow 
CC 
Cubic Centimeter 
CDE 
Common Data Elements 
CVR 
Cerebrovascular reactivity  
cGMP 
cyclic guanosine monophosphate 
CO2 
Carbon dioxide 
CVLT  
California Verbal Learning Test 
DOD 
Department of Defense 
DSMP 
Data Safety Monitoring Plan 
DTI 
Diffusion tensor imaging 
DTI-SPGR 
Diffusion Tensor Imaging - Spoiled Gradient Echo 
DVI 
Diffuse Vascular Injury 
DWI  
Diffusion Weighted Imaging 
Et   
End Tidal (CO2) 
FDA 
Food and Drug Administration 
FLAIR 
Fluid attenuated inversion recovery 
fMRI 
Functional Magnetic Resonance Imaging 
GCP 
Good Clinical Practices 
GEE 
Generalized Estimating Equations 
GLP 
Good Laboratory Practices 
GMP 
Good Manufacturing Practices 
GRE 
Gradient Echo 
HIPAA 
Health Insurance Portability and Accountability Act 
ICH 
International Conference on Harmonisation 
IND 
Investigational New Drug 
IRB 
Institutional Review Board 
ML 
Milliliters  
MR 
Magnetic Resonance 
MRI 
Magnetic Resonance Imaging 
MPRAGE 
Magnetization Prepared Rapid Gradient Echo 
mTBI 
Mild Traumatic Brain Injury 
NAION  
Non-arteritic Anterior Ischemic Optic Neuropathy 
NIH 
National Institutes of Health 
NIH CC 
National Institutes of Health Clinical Center 
NINDS 
National Institutes of Neurological Disease and Stroke 
NO 
Nitric Oxide 
NOS 
Nitric Oxide Synthase 
PDE5 
Phosphodiesterase 5 (inhibitors) 
PI 
Principal Investigator 
QC 
Quality Control 
REDCap 
Research Electronic Data Capture 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
2 
rfcMRI 
Resting state functional connectivity MRI 
SAE 
Serious Adverse Event 
Sildenafil 
Viagra® 
SWI 
Succeptability Weighted Imaging 
SWLS 
Satisfaction with Life Scale 
TBI 
Traumatic Brain Injury 
TCVI 
Traumatic Cerebral Vascular Injury 
TCD 
Transcranial Doppler 
TMT 
Trail Making Tests 
TTP   
Time to Peak 
UTSWMC 
University of Texas Southwestern Medical Center 
WAIS-IV 
Wechsler Adult Intelligence Scale 
WRAT  
Wide Range Achievement Test 
Table 1. List of Abbreviations. 
 
 
 
STATEMENT OF COMPLIANCE 
 
(1) The trial will be carried out in accordance with Good Clinical Practice (GCP) as required 
by the following):  
• 
United States (US) Code of Federal Regulations (CFR) applicable to 
clinical studies (45 CFR Part 46, 21 CFR Part 50, 21 CFR Part 56, 21 
CFR Part 312, and/or 21 CFR Part 812)  
• 
ICH E6  
 
All key personnel (all individuals responsible for the design and conduct of this 
trial) have completed Human Subjects Protection Training.]  
 
Principal Investigator:   Kan Ding, M.D. 
 Print/Type Name 
 
Signed:                                                                      Date: ___         
 
PROTOCOL SUMMARY 
Title: 
Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Précis: 
 
About 300,000 people are hospitalized for traumatic brain injury 
(TBI) each year (1, 2). After TBI, secondary brain injury escalates 
due in part to heightened levels of oxidant injury, inflammation, and 
vascular injury. Traumatic cerebral vascular injury (TCVI) may begin 
almost immediately after the primary injury and evolve into chronic 
neurodegenerative conditions. TCVI is a very complex TBI 
endophenotype and microvascular injuries have been described in a 
plethora of animal and human TBI studies. These injuries consist of 
endothelial injury, disruption of the blood brain barrier (BBB), a 
reduction of capillary density, intravascular microthrombi, and white-


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
3 
matter degeneration (3-13). Recently, use of magnetic resonance 
imaging (MRI)-Blood Oxygen Level Dependent (BOLD)  combined 
with hypercapnia (high spatial and temporal resolution) by our 
research group has proven to be more sensitive at measuring 
alterations of cerebral blood flow (CBF) in TBI subjects. The goal of 
our proposed research is to test the efficacy of Viagra® (sildenafil) at 
normalizing CBF and improving cognitive outcomes in people that 
have experienced a TBI. Sildenafil is a phosphodiesterase-5 (PDE-
5) inhibitor that has previously been administered as a therapy for 
high blood pressure and erectile dysfunction (14, 15). In people that 
have been affected by stroke-induce neurotrauma, sildenafil 
improved CBF and was found to be neuroprotective (16-21). With 
respect to chronic TBI, our preliminary data demonstrates that 
sildenafil therapy potentiates cardiovascular reactivity (CVR) in 
areas of the brain with damaged endothelium. In this proposal, we 
will test the hypothesis that sildenafil treatment in boxers/MMA 
fighters soon after concussion normalizes CBF, potentiates CVR, 
reduces post-concussion symptoms, and improves cognition.  
 
Objectives: 
 
Objective 1: To demonstrate that administration of the vasodilator, 
sildenafil, to concussed boxers/MMA fighters will improve/normalize 
various vascular properties. 
Objective 2: We will determine if sildenafil reduces symptoms and 
improves cognition in the athletes.  
 
 
 
 
 
Endpoint 
The primary outcome measures will be global CVR to hypercapnia, 
reduced symptoms, improved cognition in concussed athletes 
treated with a single or multiple doses of sildenafil (60mg). In the 
secondary outcome measure, we assess sildenafil (60mg) therapy 
reduces the levels of fluid-based biomarkers of injury.  
 
 
 
Population: 
The study population for this protocol consists of 100 boxers 
between the ages of 18 and 35 (both men and women) who have 
suffered a concussion. The athletes will be recruited from fitness 
centers within the North Texas area. Testing will occur at UT 
Southwestern Medical Center, Dallas, Texas. The study will be 
comprised of the experimental (boxers/MMA fighters) and age-
matched non-boxer, healthy controls. 
 
Phase: 
 
2 
 
Number of Sites 
enrolling 
participants: 
 
 
1 
 
 
 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
4 
Description of Study 
Agent : 
Sildenafil is a phosphodiesterase-5 (PDE-5) inhibitor that has 
previously been administered as a therapy for high blood pressure 
and erectile dysfunction. Sildenafil (60mg) will be administered at 
various time-points to the athletes to assess efficacy and tolerability. 
 
Study Duration: 
 
3 Years 
 
Participant Duration: 
 
30 Days 
 
SCHEMATIC OF STUDY DESIGN 
 
 
Figure 1. Sildenafil Pilot Study. 
 
 
 
1 
KEY ROLES 
 
Name, degree, title: Kan Ding, M.D.; Assistant Professor  


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
5 
Role: PI (Contact PI) 
Institution Name: UT Southwestern Medical Center (UTSWMC) 
Address: 5323 Harry Hines Blvd, Dallas, Texas  75390  
Phone Number: 214-648-9197; Email: Kan.Ding@utsouthwestern.edu  
 
 
Name, degree, title: Christopher Madden MD; Professor  
Role: co-I, Medical Monitor; Institution Name: UTSWMC 
Phone Number: 214-648-0499; Email: Christopher.madden@utsouthwestern.edu  
 
 
2  
INTRODUCTION: BACKGROUND INFORMATION AND SCIENTIFIC 
RATIONALE  
 
2.1 
BACKGROUND INFORMATION  
 
Traumatic Brain Injury (TBI). Each year in the United States, about 235,000 persons are 
hospitalized for TBI, of which approximately 50,000 die. The cost of TBI each year is 
approximately $77 billion in the U.S. (Injury Prevention and Control: Traumatic Brain Injury; 
<www.cdc.gov/traumaticbraininjury/statistics.html>). Despite advances in neurosurgical 
interventions and acute monitoring, many survivors do not fully recover and are left with 
permanent disability (1, 2, 22, 23). Secondary brain damage which is caused by oxidant injury, 
inflammation, and vascular injury, may begin almost immediately after the primary injury.  Even 
those with mild TBI may have prolonged neurological deficits, with about 15% having disabling 
persisting symptoms. 43% of those hospitalized for TBI have long-term disability (24-26). 
Consequently, chronic secondary brain injury is difficult to manage and the administration of 
neuroprotective agents in a chronic fashion is warranted to assist in the recovery process and 
decrease neuro-degeneration in this population. Multiple studies that aimed to treat mild TBI 
acutely with various interventions showed poor results (27). These limited findings may be due 
to insufficient treatment times, ineffective therapies, or lack of endophenotype data. 
Endophenotype guided therapies are ideal and may yield drug therapies that reduce secondary 
brain injury and improve outcomes within the TBI population.  
 
Vascular Injury and TBI. Traumatic cerebral vascular injury (TCVI) is a debilitating TBI 
endophenotype. In both animal and human TBI models, TCVI results in vasodilatory deficits and 
other microcirculatory problems. In these models, the response to vasodilators such as nitric 
oxide (NO) was reduced significantly. Also, these deficits were a result of damage to the 
endothelium, a reduction of capillary density, intravascular microthrombi, and white-matter 
degeneration, resulting in motor and cognitive deficits (3-13, 28).  
Following TCVI, cerebral blood flow (CBF) is affected in TBI subjects as indicated by 
hypo-perfusion in numerous brain structures. For example, CBF has been found to be reduced 
significantly in people who have experienced a severe TBI, resulting in poor long-term cognitive 
and functional outcomes (29-32). Also, CVR is decreased after TBI and correlates with reduced 
CBF, cognitive deficits, and heightened symptoms (33, 34). Other studies have demonstrated 
that at chronic time-points, the CBF remained abnormal in athletes even though they showed 
improvements with cognitive scoring and reduced symptoms at later time-points (35-38). 
Imaging diagnostics have proven to be vital in detecting TCVI in both symptomatic and 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
6 
asymptomatic TBI subjects and should be utilized to monitor disease progression and efficacy 
of various treatments.  
Imaging tools such as transcranial doppler (TCD) and near infra-red spectroscopy 
(NIRS) have been shown to measure vasospasms and CVR abnormalities in TBI survivors. A 
major limitation of TCD and NIRS is their lack of sensitivity, which has been demonstrated in a 
number of research studies (39-45), warranting the use of a more sensitive approach for 
identifying CBF and CVR abnormalities. Utilization of magnetic resonance imaging (MRI)-Blood 
Oxygen Level Dependent (BOLD) combined with hypercapnia (high spatial and temporal 
resolution) by our group and others has proven to be more effective in determining the 
hemodynamic response in TBI subjects (46-48). In control and injured people, MRI-BOLD 
measures the transition rate of oxygenated hemoglobin to deoxygenated hemoglobin and 
defines the regional/global CBF in the brain (49). Recently, preliminary data generated by our 
research group has proven that CBF and CVR are decreased in people with a history of TBI. 
The primary goal of this study is test whether sildenafil improves global CBF/CVR, reduces 
symptoms, and improves cognition in concussed athletes.  
 
Sildenafil Therapy to Improve CBF and CVR. Sildenafil is a vasodilator that inhibits the 
cGMP-specific phosphodiesterase type 5 enzyme, resulting in decreased degradation of cGMP. 
The original use of this drug was to treat hypertension and later for erectile dysfunction (50-52). 
This drug is relatively safe and has been shown to increase CVR in a number of studies (53, 
54). For example, in 28 patients randomized to either placebo or sildenafil, an increase in CVR 
was observed as early as 1 hour after administration (54). In another study, utilization of TCD 
showed that a single 50mg dose of sildenafil in patients with vertebra-basilar insufficiency 
displayed a significant increase in the diameter, area, and flow volume of the vertebral artery 
(55). In contrast, in healthy individuals, no effect on CBF was observed when treated with 
sildenafil (56, 57). Preliminary data generated by our research group demonstrates that 
sildenafil is efficacious at normalizing CBF and increasing CVR in TBI patients. Given the 
paucity of studies testing the effect of sildenafil on CBF/CVR, in this novel study, we plan to test 
the hypothesis that sildenafil normalizes global CBF and potentiates CVR in concussed 
professional boxers. 
 
 
2.2 
RATIONALE  
 
Since we have the capability to obtain baseline (prefight) data, this population is an ideal group 
to study the efficacy of sildenafil at normalizing CBF, potentiating CVR, improving cognition and 
symptoms. The use of sildenafil is based on published reports in stroke models and preliminary 
data generated from our research group in TBI subjects. After suffering a concussion, we 
believe that this compound will effectively diminish the secondary injury in the brain and mitigate 
symptoms and cognitive deficits. Also, this therapy has proven to be safe in people suffering 
from TBI. 
 
 
 
2.3 
POTENTIAL RISKS AND BENEFITS  
 
2.3.1 KNOWN POTENTIAL RISKS  
 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
7 
Sildenafil: There is a serious risk in subjects with pre-existing cardiovascular disease, 
hypotension (BP <90/50)/hypertension (BP> 170/110), coronary heart disease, subjects with 
retinitis pigmentosa there is cardiac risk. 
 
MRI: Subjects are at risk for injury from the MRI magnet (3 Tesla) if they have pacemakers or 
other implanted electrical devices, brain stimulators, some types of dental implants, aneurysm 
clips (metal clips on the wall of a large artery), metallic prostheses (including metal pins and 
rods, heart valves, and cochlear implants), permanent eyeliner, implanted delivery pump, or 
shrapnel fragments. Welders and metal workers are also at risk for injury because of possible 
small metal fragments in the eye of which they may be unaware. Volunteers will be screened for 
these conditions before having an MRI, and if any are present, the MRI scan will not be 
performed.  Volunteers will be asked specifically about metal objects being present in their 
body. If it is unknown whether metal is present and or if there is any question, MRI will not be 
performed.  
Subjects with fear of confined spaces may become anxious during an MRI. Those with back 
problems may have back pain or discomfort from lying in the scanner.  The noise from the 
scanner is loud enough to damage hearing, especially in people who already have hearing loss.  
 
Neuropsychological Testing: There are no expected risks for the participants answering the 
questions. Possible adverse events may include psychological stress.  
 
Blood/Saliva collection: The risk of bruising or infection are the main risks involved with the 
blood collection procedures. There are no known risks of providing a saliva specimen. 
 
2.3.2 KNOWN POTENTIAL BENEFITS  
 
The information collected from this study will further our knowledge of secondary brain injury 
after TBI. Also, we will assess whether sildenafil therapy alters blood flow, which is 
hypothesized to be protective after TBI. Even though this study does not offer direct benefit to 
participants, the data collected will help shape how TBIs are managed in the future. The MR 
images will be collected for research purposes only. If any abnormalities are observed we will 
contact the medical monitors. The benefits outweigh the risks associated with this study.   
 
 
 
3 
OBJECTIVES AND PURPOSE 
 
The main objective of this clinical trial is to test the hypothesis that sildenafil treatment in active 
professional boxers/MMA fighteres soon after concussion normalizes CBF, potentiates CVR, 
reduces symptoms, improves cognition, and is a tolerable therapy. If our hypothesis is 
supported, sildenafil will shape how secondary brain injury is treated and will improve long-term 
outcomes after TBI. 
 
 
 
4 
STUDY DESIGN AND ENDPOINTS 
 
4.1 
DESCRIPTION OF THE STUDY DESIGN 
 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
8 
In this placebo-controlled, double-blinded clinical trial, approximately 100 boxers/MMA 
fighters that have experienced a concussion or a significant number of sub-concussive blows 
will be treated with a placebo pill or Viagra® (sildenafil; 60mg) once (single-dose therapy) or 
once-a-day for 14 days. This is a phase 2 study that will be conducted at a single-site 
(UTSWMC, Dallas, Texas). 
Prior to competition, the medical/concussion history and a blood (8ml) and saliva sample 
will be collected at the baseline (pre-fight) visit. Also, a battery of neuropsychological exams 
(NIH Common Data Elements) and a magnetic resonance imaging (MRI) scan will be performed 
at UT Southwestern Medical Center Advanced Imaging Research Center to obtain cognitive, 
structural, and functional baseline data. 
At day1-3 and 30 after injury, the boxers will undergo the MRI structural and MRI BOLD 
(with hypercapnia) procedures at UT Southwestern Medical Center Advanced Imaging 
Resource Center. The subjects will also undergo neurpsychological testing, and blood/saliva 
collection for tests to determine the efficacy of sildenafil. A randomization schedule will be 
prepared by the study statistician. Randomization will be 1:1 sildenafil:placebo, and will be in 
blocks of 2.  Investigators associated with this study will not have access to the randomization 
schedule. The principal investigator, study team, and study subjects will be blinded in this study. 
To monitor the drug administration, a daily diary will be filled out by the participant. The 
tolerability of sildenafil in boxers will also be assessed. 
A total of 130 boxers will be screened and only 100 boxers will be enrolled in this study 
to complete the study aims. The study participants will not be responsible for any research 
related costs, which include travel and parking when visiting UTSWMC for the collection of 
blood/saliva, neuropsychological testing, and MR imaging. The participants will be compensated 
for their time.  
The participants in group 1 (single therapy) will consist of the active boxers/MMA 
fighters that experience significant sub-concussive blows or a concussion during competition. In 
this group, 65, professional male/female boxers/MMA fighters within the North Texas region will 
be screened and about 50 concussed athletes will be enrolled. The athletes that have at least 
25 blows to the head and a Symptom Score > 1 on at least 3 items from the Rivermead Post-
Concussion Questionnaire following their fight will be enrolled in this study. The research 
subjects will be treated with sildenafil (60mg), once at 2 hours after experiencing a concussion.  
Group 2 will consist of the active boxers/MMA fighters that experience significant sub-
concussive blows or a concussion during competition. In this group, 65, professional 
male/female boxers/MMA fighters within the North Texas region will be screened and about 50 
concussed athletes will be enrolled. The athletes that have at least 25 blows to the head and a 
Symptom Score > 1 on at least 3 items from the Rivermead Post-Concussion Questionnaire 
following their fight will be enrolled in this study. Once enrolled, the subjects will be treated with 
sildenafil (60mg) once-a-day for 14 days.  
 
Healthy Control group: In this study, 80, age (between 18 and 35)-matched healthy 
controls will be enrolled. The control subjects will participate in neuropsychological testing, 
blood/saliva collection, and the MR imaging procedures.  Healthy controls will be tested in group 
1 (n=40) and 2 (n=40) and randomized to receive either sildenafil or placebo in this group. 
 
 
 
 
 
 
4.2 
STUDY ENDPOINTS 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
9 
 
4.2.1 PRIMARY ENDPOINT: 
 
To determine if sildenafil administration improves CBF/CVR, reduces symptoms, and 
improves cognitive performance in concussed boxers/MMA fighters. Hypothesis: Both 
single and multiple sildenafil therapy improves CBF/CVR, symptoms, and cognition in 
concussed boxers. Also, long-term administration of daily doses of sildenafil to concussed 
boxers/MMA fighters is well tolerated. Following injury, we will enroll 100, active boxers/MMA 
fighters and 80, controls into a double-blind, placebo-controlled study. At a 1:1 ratio, the 
subjects will receive a single treatment of either placebo or sildenafil. The purpose of this study 
is to determine if sildenafil treatment improves CBF/CVR, reduces symptoms, and improves 
cognitive outcomes. In this study we will treat the injured athletes once (within 2 hours of injury) 
or daily (for 14 days) to determine if sildenafil improves outcomes. Previous clinical studies 
conducted by our research group, we found that sildenafil treatment (60mg) is tolerable within 
the TBI population. The athletes will maintain a daily diary of symptoms. At day 1-3 and 30 after 
injury, the CBF/CVR MR imaging procedures, the Rivermead Post Concussion Symptom 
Questionnaire, and neuropsychological assessments (NIH Common Data Elements) will be 
conducted to study the effect of sildenafil therapy. Blood (8cc) and saliva will also be collected 
to measure brain biomarkers of injury. Tolerability (blood testing and symptom reporting) 
assessments will be conducted throughout the study to ensure that the symptomatic boxers 
tolerate multiple, daily doses of sildenafil. 
 
 
4.2.1.a. MRI  
Preparation for the MRI procedure: 
At baseline and post-concussion time-points (day 1-3, 30), the research coordinator will 
schedule the imaging procedure with the subject. There will be a 3-day window to facilitate 
scheduling of the MRI studies.   Once the subject arrives to UT Southwestern Medical Center 
(Dallas, Texas), the research coordinator will escort the participant to the Advanced Imaging 
Resource Center for the MR imaging session. Prior to conducting the imaging procedures, the 
subjects will be screened for MRI safety using the Screening Questionnaire. The subjects may 
be asked to lie still for up to 7-10 minutes at a time. While in the scanner they will hear loud 
knocking noises, and they will be fitted with earplugs or earmuffs to muffle the sound. They will 
be able to communicate with the MRI staff at all times during their scan, and they may ask to be 
moved out of the machine at anytime. Participants will first have a structural MRI scan.  
The structural MRI sequences we will use do not require contrast. The subjects will not 
be required to do any tasks during the structural MRI.  Sequences used for the structural MRI 
include T1 Magnetization Prepared Rapid Gradient Echo (MPRAGE), Fluid Attenuated Inversion 
Recovery (FLAIR), Diffusion Tensor Imaging (DTI), resting state functional connectivity (rfMRI), 
diffusion weighted imaging (DWI), Arterial Spin  
Labeling (ASL) to assess resting CBF, gradient echo (GRE) and/or T2* susceptibility weighted 
imaging (SWI).  If image quality of a given sequence is inadequate due to patient motion for 
example, these may be repeated at the discretion of the MRI technologist or radiologist. The 
structural scan takes approximately 45 minutes. 
The BOLD sequence with hypercapnia challenge:   
The participants will have a BOLD MRI scan (baseline, day 1-3, and 30 after injury) with 
CVR hypercapnia measurements. Global and region-specific CVR will be assessed using 
hypercapnia induced by breathing 5% carbon dioxide (CO2) mixed with 21% O2 and 74% N2.  
Study participants will be taken out of the scanner after the initial 45-minute structural scan and 
fitted with a breathing mask that covers the mouth and nose (similar to a C-PAP mask).  After 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
10 
the mask is in place, the patient is placed back into the magnet.  Hypercapnia will be induced 
via a Douglas bag fitted with a valve to switch between room air and 5% CO2.  A research 
assistant will be inside the magnet room throughout the BOLD scan with hypercapnia challenge 
to switch the valve and monitor the subject.  Physiologic parameters, including end-tidal 
(EtCO2), breathing rate, heart rate, and capillary oxygenation will be monitored continuously 
during the experiment using a capnograph and pulse oximeter.  The type of gas breathed is 
switched every minute similar to a block design fMRI experiment, while Blood Oxygen Level 
Dependent (BOLD) MRI Images are acquired for 7 minutes.   
Times are close approximations which may be altered depending on the cooperation of 
the patient.  The subject will not engage in the hypercapnia challenge for more than the 
specified 7 min. Total scan time with structural and BOLD sequences will be approximately 1 
hour.  
MRI patient procedures: 
1. Safety screening 
2. 45 min structural scan  
3. Out of the magnet and fitted with the mask for hypercapnia challenge 
4. 7 min. BOLD scan with mask and hypercapnia 
 
 
4.2.1.b. TBI Neuropsychological Assessments 
 In this clinical study, we test whether sildenafil improves cognitive, mood, and functional 
outcomes in injured boxers. The testing procedures will be conducted in a quiet room at 
UTSWMC by a neuropsychologist or trained coordinator. We anticipate that the testing 
procedures will take approximately 1 hour to complete. The subjects will be given frequent rests 
and they have the right to refuse to answer any questions or to stop a test at any time and for 
any reason. TBI phenotyping instruments recommended for evaluation in all TBI cohort or 
natural history studies have been labeled the TBI Common Data Elements (CDEs)(58).The 
subject will be interviewed, complete questionnaires, take pen-and-paper tests, and perform 
simple actions. 
  
 
 
 
In this study we will include the following selected subset of assessments taken from the CDE’s: 
 
 
• Hopkins Verbal Learning Task (HVLT). The Hopkins Verbal Learning Test (HVLT) is a 
brief verbal learning and memory test with six alternate forms of 12 words. 
• The Sport Concussion Assessment Tool (SCAT5), from the Concussion in Sport Group, 
is a standardized tool for evaluating injured athletes for concussion and can be used in 
athletes aged 13 years and older. This test will take approximately 30 minutes. 
• Satisfaction with Life Scale (SWLS): is a short 5-item instrument designed to measure 
global cognitive judgments of satisfaction with one's life. The scale usually requires only 
about one minute of a respondent's time.  
• Rivermead Post-Concussion Symptom Questionnaire: rate the severity of 16 different 
symptoms commonly found after a TBI (5 min). 
• Galveston Orientation and Amnesia Test (GOAT)-modified for sports athletes 
 
 
 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
11 
 
4.2.2 SECONDARY ENDPOINT:  
 
To determine if sildenafil reduces the blood/saliva levels of brain biomarkers of injury 
after concussion.  The goal of this study is to produce pilot efficacy data to design a definitive 
study aimed at testing the efficacy of the administration of sildenafil at reducing the blood/saliva 
levels of Von willebrand factor (vWF), glial fibrillary acidic protein (GFAP), neurofilament-H 
(NFL-H), creatine kinase-B (CKBB) and tau. In brief, about 8cc of blood and saliva will be 
collected at each time-point. The blood and saliva will be collected once at baseline and on day 
1-3 and 30 after injury. Upon collecting the samples, the blood will be centrifuged at 4 degrees 
Celsius for 10 minutes at 1500 rpm. The plasma/saliva will be collected and aliquoted into 1 ml 
tubes and immediately frozen at -80 degrees Celsius. To measure the levels of brain 
biomarkers, the plasma levels of vWF, GFAP, NFL-H, CKBB, and tau will be measured using 
the enzyme-linked immunoassay according to the manufacturer’s instructions. Each sample will 
be loaded onto the 96-well plate in triplicate. Each sample will be tested in triplicate. The plate 
will be incubated for 2 h at room temperature, washed, and 200 µl of the substrate will be added 
for 90 min at room temperature. After 90-min, the absorbance will be detected at 405 nm. The 
values will be compared to the standard curve and the concentration of the biomarker will be 
determined.  
 
 
 
5 
STUDY ENROLLMENT AND WITHDRAWAL 
 
5.1   PARTICIPANT INCLUSION CRITERIA 
 
      FOR ATHLETES 
1. Age 18-35 
2. Male or female professional boxers/MMA fighters 
3. Ability to undergo MR imaging procedures 
4. At least one of the following: 
a. 
KO/TKO scored by fight referee.  
b. 
Greater than 25 blows to the head. 
5. Significant post-concussive symptoms (Symptom Score > 1 on at least 3 items from the 
Rivermead Post-Concussion Questionnaire)  
FOR CONTROLS 
1. Age 18-35 
2. Male of female who do not participate in contact sports 
3. Screen negative for mTBI using Ohio State TBI ID 
 
5.2    PARTICIPANT EXCLUSION CRITERIA 
 
1. Contraindication to sildenafil which includes the following: 
a. Current use of organic nitrate vasodilators 
b. Use of ritonavir (HIV-protease inhibitor) 
c. Current use of erythromycin, ketoconazole, or itraconazole 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
12 
d. Current use of cimetidine 
e. Current resting hypotension (BP < 90/50 mm Hg) 
f. Current severe renal insufficiency (Creatinine Clearance < 30mL/min) 
g. Current hepatic cirrhosis 
h. Current cardiac failure or coronary artery disease causing unstable angina 
i. 
Retinitis pigmentosa 
j. 
Known hypersensitivity or allergy to sildenafil of any of its components 
2. Daily therapy with a PDE5 inhibitor within the past 2 months 
3. Immediate hospitalization for severe concussion 
4. History of neurological or psychiatric disorder not related to TBI 
5. Known inclusion in another interventional clinical trial 
6. Subjects with metal implants that would interfere with the MR imaging procedures 
7. Sickle cell disease 
8. History of priapism 
 
 
 
5.3 
STRATEGIES FOR RECRUITMENT AND RETENTION 
 
Within the North Texas area there are approximately 130 boxing training centers. Over the last 
6 years we have built relationships with trainers at these facilities and about 125 boxers have 
previously been enrolled in both observational and interventional studies conducted by the 
Gatson laboratory. We have been successful with enrolling athletes (boxers, MMA fighters, etc.) 
and completing the clinical studies with a very low dropout rate (10%). Thus, we believe that will 
meet study recruitment and experience very little dropouts.Our target sample size is 100 
athletes. We will also recruit 80 healthy controls.  
 
 
 
5.4 
PARTICIPANT WITHDRAWAL OR TERMINATION 
 
5.4.1 REASONS FOR WITHDRAWAL OR TERMINATION 
 
In this study, the participants will be allowed to withdraw at any point. Also, the PI and/or study 
investigators may choose to withdraw a participant at any time. The reason for withdrawing 
participants may be for administrative purposes, non-compliance, and/or medical reasons.  
 
 
5.4.2 HANDLING OF PARTICIPANT WITHDRAWALS OR TERMINATION 
 
If a subject withdraws or is withdrawn from the study, any remaining unused samples and/or 
data identified as theirs will be destroyed at their request. If the PI or study investigators do not 
receive a request, then the samples will contiunue to be used in the analysis as applicable. 
 
 
 
5.5 
PREMATURE TERMINATION OR SUSPENSION OF STUDY 
 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
13 
Drs. Joseph Minei and Christopher Madden, who are the medical monitors, have the authority to 
halt the study, remove individual subjects from the study, and take whatever steps are 
necessary to protect the safety and well-being of research subjects. An independent monitor 
from UTSWMC will also have the capability to stop a study for safety reasons.  
 
The medical monitors, PI, Independent monitor, and IRB will assess the measures taken by the 
study team in response to safety issues that caused the study to be stopped or suspended. 
Revised safety measures taken by the study team will be in a written report submitted to the 
medical monitor, UTSWMC monitor and IRB of record. Only when these entities agree in writing 
that the problems have been satisfactorily addressed,the protocol may be re-activated.  
 
 
 
6 
STUDY AGENT 
 
6.1 
STUDY AGENT(S) AND CONTROL DESCRIPTION 
 
6.1.1 ACQUISITION 
 
Sildenafil (60mg) and placebo tablets will be ordered from Pfizer and delivered to the UTSWMC 
pharmacy. The UTSWMC pharmacy will be responsible for packaging the study drug and 
devising the randomization schedule. 
 
 
 
6.1.2 FORMULATION, APPEARANCE, PACKAGING, AND LABELING 
 
Sildenafil is supplied as blue, film-coated, rounded-diamond-shaped tablets containing sildenafil 
citrate equivalent to 60 mg of sildenafil. The placebo pills will be compounded and have similar 
appearance to the investigational drug. 
 
 
 
6.1.3 PRODUCT STORAGE AND STABILITY 
The drug will be stored at room temperature (25°C [77°F]) with excursions permitted (59-86°F). 
 
6.1.4 PREPARATION 
 
The study drug is in pill format. The participant will self administer the sildenafil pill. The study 
participant will maintain a daily diary to document the administration of the study drug. 
 
 
 
6.1.5 DOSING AND ADMINISTRATION 
 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
14 
In the first and second group, the participants will be administered either a single-dose or 14 pills 
of placebo or sildenafil (60mg) after suffering  a concussion. The first dose will be taken at 2hours 
after injury. 
 
 
 
6.1.6 ROUTE OF ADMINISTRATION 
Oral 
 
 
6.1.7 DOSE ADJUSTMENTS/MODIFICATIONS/DELAYS 
N/A 
 
6.1.8 DURATION OF THERAPY 
 
The duration of the study for the primary and secondary endpoints will be 30 days.  
 
 
 
6.1.9 TRACKING OF DOSE 
 
During the course of this study, the participant will maintain a drug diary and document when 
the treatment was administered. Once the participant completes the study, the pill bottle will be 
collected and the remaining pills in each bottle will be counted.  
 
 
 
6.1.10 DEVICE SPECIFIC CONSIDERATIONS 
N/A 
 
6.2 
STUDY AGENT ACCOUNTABILITY PROCEDURES 
 
The UTSWMC pharmacy will create the randomization schedule. The study coordinator will 
follow the randomization schedule and deliver the pill bottles to the participant. Instructions will 
be given the research subject pertaining to daily documentation of drug administration and 
returning the pill bottles at the completion of the study.  
 
 
 
7 
STUDY PROCEDURES AND SCHEDULE 
 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
15 
7.1 
STUDY PROCEDURES/EVALUATIONS 
7.1.1 STUDY SPECIFIC PROCEDURES  
Prior to performing any study procedures, consent will be obtained. All of the evaluations and 
procedures will performed for research purposes only. None of the tests will be for clinical 
purposes. In table 2, the study procedures are listed for the athletes that will be treated with 
sildenafil after competition and procedures for the controls.  
 
7.1.2 STANDARD OF CARE STUDY PROCEDURES  
N/A 
 
7.2 
LABORATORY PROCEDURES/EVALUATIONS 
 
7.2.1 CLINICAL LABORATORY EVALUATIONS  
 
Biochemistry: 
Blood (~8cc) will be collected and the blood albumin, alkaline phosphatase, total bilirubin, 
bicarbonate, BUN, calcium, chloride, creatinine, glucose, LDH, phosphorus, potassium, total 
protein, SGOT [AST], SGPT [ALT], sodium, and coagulase levels will be measured from  from 
the participants at day 1-3 and 30 after injury. By performing these tests we will be able to 
detect side effects that may be associated with the study drug. For example, if the AST or ALT 
ratio is out of the normal range, the participant(s) will be withdrawn from the study. Also, if the 
participant reports any side effects that may be linked to the study drug, the study participant will 
be withdrawn from the study. The IRB and FDA will be notified within 7 business days. The 
Boxers (n=100); Controls (n=80) 
Baseline 
Day 1-3 
Day 7 
(phone) 
Day 15 
(phone) 
Day 22 
(phone) 
Day 
30 
1. Inclusion/Exclusion Criteria 
X 
 
 
 
 
 
2.  Informed Consent 
X 
 
 
 
 
 
3.  Blood/saliva collection (side 
effects, tolerability, brain biomarkers) 
X 
X 
 
 
 
X 
4. Structural MRI (T1 MPRAGE, 
FLAIR, DTI, rsBOLD) 
X 
X 
 
 
 
X 
5. Randomization 
 
X 
 
 
 
 
6. Dispensing study drug (sildenafil 
or placebo) 
 
X 
 
 
 
 
7. Pill counting for compliance 
 
 
 
 
 
X 
8. Monitoring for adverse effects 
 
X 
X 
X 
X 
X 
9.  Symptom inventory 
 
X 
X 
X 
X 
X 
10.  Neuropsychometric CDEs 
X 
X 
 
 
 
X 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
16 
testing will be performed by Quest diagnostics, Dallas, Texas. Blood will also be collected to 
measure the levels of brain biomarkers of injury within the athletes. 
 
 
 
7.2.2 OTHER ASSAYS OR PROCEDURES 
 
N/A 
 
 
 
7.2.3 SPECIMEN PREPARATION, HANDLING, AND STORAGE 
 
At baseline and on day 1-3 and 30 after TBI, the blood/saliva samples will be collected. 
About 8cc of blood will collected and after clotting, the sample will be centrifuged at 4 degrees 
Celsius for 10 minutes at 1300g. The blood will be centrifuged within 1 hour of collection. The 
plasma and saliva will be collected and aliquoted into 1 ml cryovial tubes and immediately 
frozen at -80 degrees Celsius. Information pertaining to each sample will be added to the 
specimen log. All personnel will be trained in accordance to the CDE recommendations. 
 
 
 
7.2.4 SPECIMEN SHIPMENT 
 
For the biochemistry, we will schedule the Quest Diagnostics courier to collect the 
samples at UTSWMC to deliver the blood samples to Quest Diagnostics for analysis.  
 
Quest Diagnostics 
11613 North Central Expressway #120 
Dallas, Texas  75243  
 
 
 
7.3 
STUDY SCHEDULE 
 
7.3.1 SCREENING 
                Boxers that meet the baseline study criteria will be approached  and if interested they 
will be consented to participate in the study procedures. Medical and concussion history will be 
reviewed at the baseline time-point to determine which boxers will be considered to participate 
in the study. The research coordinator/boxing consultant will identify the athletes that have 
experienced greater than 25 blows to the head or a Symptom Score > 1 on at least 3 items from 
the Rivermead Post-Concussion Questionnaire following the boxing match.  Once the subject 
has been identified, the research personnel will review the subject’s chart to determine if they 
meet criteria for enrollment into the study. If so, the participant will be approached to obtain 
consent where the patient has the right to ask questions about the study.  
  
 
 
7.3.2 ENROLLMENT/BASELINE/FOLLOW-UP 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
17 
 
Sildenafil Study: 
Baseline Visit (Visit 1, Day 0)  
• 
Obtain informed consent of potential participant verified by signature on study informed 
consent form  
• 
Verify inclusion/exclusion criteria  
• 
Obtain demographic information, medical history, head injury history, medication history, 
alcohol and tobacco use history 
• 
Record vital signs, results of examinations, other assessments.  
• 
Baseline symptom questionnaire 
• 
Collect blood/saliva for biochemistry, biomarker testing 
• 
MRI procedures  
• 
Neuropsychological testing 
• 
 
Follow-up Visit (Visit 2, 2 hours after injury)  
• 
Administer sildenafil (60mg) or placebo once of daily for 14 days 
 
Follow-up Visit (Visit 3, Day 1-3)  
• 
Record adverse events  
• 
Collect blood/saliva for biochemistry, biomarker testing 
• 
Administer sildenafil or placebo (once)  
• 
MRI procedures  
• 
Neuropsychological testing 
 
Follow-up Visit (Visit 4, Day 30)  
• 
Symptom questionnaire 
• 
Collect blood/saliva for biochemistry, biomarker testing 
• 
MRI procedures  
• 
Neuropsychological testing 
 
Follow-up Visit (Visit 5 [Phone Visit], Day 14 after completion of the study)  
• 
Symptom questionnaire 
• 
Safety Assessment 
 
 
 
7.3.3 EARLY TERMINATION VISIT 
 
If the study is terminated early, the final visit would consist of collecting a blood/saliva 
sample and administering the neuropsychological testing and symptom questionnaire (at time-


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
18 
points after day 10 after injury). The MRI scan would also be necessary in cases where the 
study ends after the 10-day post-enrollment. 
 
 
   
7.4 
JUSTIFICATION FOR SENSITIVE PROCEDURES 
 
In this study, placebo will be used as a comparator to assess whether sildenafil improves 
CBF, potentiates CVR, reduces symptoms, and improves cognitive outcomes in the brain 
injured athletes.  
 
 
 
 
7.5 
CONCOMITANT MEDICATIONS, TREATMENTS, AND PROCEDURES  
 
7.5.1 PRECAUTIONARY MEDICATIONS, TREATMENTS, AND PROCEDURES 
 
1. Sildenafil is contraindicated for use in people that are hypersensitive to any 
component of the tablet. 
2. Sildenafil has a systemic effect vasodilatory effects, which may be augment the effect 
of other anti-hypertensive agents.  
3. Caution should be used when using Viagra and ritonavir, since concomitant 
administration of the protease inhibitor, ritonavir,  substantially increases serum 
concentrations of sildenafil. 
4. Caution is advised when Phosphodiesterase Type 5 (PDE5) inhibitors are co-
administered with alpha-blockers. 
5. Combinations of Viagra with other erectile dysfunction medications (Revatio) is not 
recommended. 
6. Sildenafil use is contraindicated with regular and/or intermittent use of organic 
nitrates.  
7. Sildenafil should not be taken with other PDE5 inhibitors. 
8. Co-administration of Cimetidine (800mg), erythromycin, or saquinavir with sildenafil is 
cautioned since a combination of any of these drugs with sildenafil results in a great 
increase in sildenafil systemic exposure. 
 
 
7.6 
RESCUE MEDICATIONS, TREATMENTS, AND PROCEDURES  
 
In cases of overdose, standard supportive measures should be adopted as required. 
Renal dialysis is not expected to accelerate clearance as sildenafil is highly bound to plasma 
proteins and it is not eliminated in the urine. 
 
 
 
7.7 
PARTICIPANT ACCESS TO STUDY AGENT AT STUDY CLOSURE  


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
19 
N/A 
 
 
8 
ASSESSMENT OF SAFETY 
 
8.1 
SPECIFICATION OF SAFETY PARAMETERS 
 
Adverse events will be reported in accordance with Federal NIH requirements. All adverse 
events, serious and non-serious, expected and unexpected, related and unrelated will be 
tracked by the study coordinator.   
 
Serious or unexpected adverse events and other unanticipated problems will be reported orally 
as soon as possible and in writing within 7 days if life-threatening and within 15 days otherwise. 
Expected or non-serious adverse events will be reported at the time of continuing review. 
 
 
 
8.1.1 DEFINITION OF ADVERSE EVENTS (AE) 
 
Adverse event means any untoward medical occurrence associated with the use of an 
intervention in humans, whether or not considered intervention-related. 
 
 
 
8.1.2 DEFINITION OF SERIOUS ADVERSE EVENTS (SAE) 
 
An AE or suspected adverse reaction is considered "serious" if, in the view of either the 
investigator or sponsor, it results in any of the following outcomes: death, a life-threatening 
adverse event, inpatient hospitalization or prolongation of existing hospitalization, a persistent or 
significant incapacity or substantial disruption of the ability to conduct normal life functions, or a 
congenital anomaly/birth defect. Important medical events that may not result in death, be life-
threatening, or require hospitalization may be considered serious when, based upon appropriate 
medical judgment, they may jeopardize the patient or subject and may require medical or 
surgical intervention to prevent one of the outcomes listed in this definition.  
 
 
 
 
8.1.3 DEFINITION OF UNANTICIPATED PROBLEMS (UP) 
 
 
Unanticipated problems involving risks to participants or others to include, in general, any 
incident, experience, or outcome that meets all of the following criteria:  
 
• 
Unexpected in terms of nature, severity, or frequency given (a) the research procedures 
that are described in the protocol-related documents, such as the IRB-approved research 
protocol and informed consent document; and (b) the characteristics of the participant 
population being studied;  


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
20 
• 
Related or possibly related to participation in the research (“possibly related” means 
there is a reasonable possibility that the incident, experience, or outcome may have been 
caused by the procedures involved in the research); and  
• 
Suggests that the research places participants or others at a greater risk of harm 
(including physical, psychological, economic, or social harm) than was previously known or 
recognized.  
 
 
 
 
8.2 
ADVERSE EVENTS 
 
8.2.1 SEVERITY OF EVENT 
 
Mild – Events require minimal or no treatment and do not interfere with the participant’s daily 
activities.  
 
Moderate – Events result in a low level of inconvenience or concern with the therapeutic 
measures. Moderate events may cause some interference with functioning. 
 
Severe – Events interrupt a participant’s usual daily activity and may require systemic drug 
therapy or other treatment. Severe events are usually potentially life-threatening or 
incapacitating. 
 
 
 
8.2.2 EXPECTEDNESS  
 
Table 4.  Adverse events attributed to sildenafil in placebo-controlled randomized trials 
Adverse Event 
% of patients on sildenafil 
reporting AE (n = 734) 
% of patients on placebo 
reporting AE (n = 725) 
Headache 
16% 
4% 
Flushing 
10% 
1% 
Dyspepsia 
7% 
2% 
Nasal Congestion 
4% 
2% 
Urinary Tract Infection 
3% 
2% 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
21 
Abnormal vision* 
3% 
0% 
Diarrhea 
3% 
1% 
Dizziness 
2% 
1% 
Rash 
2% 
1% 
*Abnormal Vision:  Mild and transient, predominantly color tinge to vision, but increased sensitivity to 
light or blurred vision.  In these studies, only one patient discontinued due to abnormal vision 
 
 
Table 5. Adverse Events Reported by Participants in Placebo Controlled RCTs, but Equally Common 
in Placebo Group (occurred in <2% of participants; relationship to Viagra unknown but plausible) 
System 
Adverse Event 
Body 
Face swelling, light sensitivity, shock, pain, chills, accidental fall , abdominal 
pain, allergic reaction, chest pain, accidental injury, body or muscle weakness 
Cardiovascular 
Chest pain, AV block, migraine, syncope, tachycardia, palpitation, 
hypotension, postural hypotension, myocardial ischemia, cerebral thrombosis, 
cardiac arrest, heart failure, abnormal electrocardiogram, cardiomyopathy. 
Digestive 
Vomiting, glossitis, colitis, dysphagia, gastritis, gastroenteritis, esophagitis, 
esophagitis, stomatitis, dry mouth, liver function tests abnormal, rectal 
hemorrhage, gingivitis.  
Hemic and Lymphatic 
Anemia and leukopenia. 
Metabolic and Nutritional 
Thirst, edema, gout, unstable diabetes, hyperglycemia, peripheral edema, 
hyperuricemia, hypoglycemic reaction, hypernatremia. 
Musculoskeletal 
Arthritis, arthrosis, myalgia, tendon rupture, tenosynovitis, bone pain, 
myasthenia, synovitis.  
Nervous 
Ataxia, hypertonia, neuralgia, neuropathy, paresthesia, tremor, vertigo, 
depression, insomnia, somnolence, abnormal dreams, reflexes decreased, 
hypesthesia.  
Respiratory 
Asthma, dyspnea, laryngitis, pharyngitis, sinusitis, bronchitis, sputum 
increased, cough increased.  
Skin and Appendages 
Urticaria, herpes simplex, pruritus, sweating, skin ulcer, contact dermatitis, 
exfoliative dermatitis.  
Special Senses 
Sudden decrease or loss of hearing, mydriasis, conjunctivitis, photophobia, 
tinnitus, eye pain, ear pain, eye hemorrhage, cataract, dry eyes.  


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
22 
Urogenital 
Cystitis, nocturia, urinary frequency, breast enlargement, urinary 
incontinence, abnormal ejaculation, genital edema and anorgasmia.  
 
 
Table 6. Post-Marketing Experiences Reported in Temporal Association with the use of Viagra.  
Occurred predominantly in patients who had preexisting cardiovascular risk factors. Undetermined if these 
events are related directly to Viagra, to sexual activity, to the patient’s underlying conditions, or to a 
combination of these factors. 
Cardiovascular and 
Cerebrovascular 
Myocardial infarction, sudden cardiac death, ventricular arrhythmia, cerebrovascular 
hemorrhage, transient ischemic attack, hypertension, subarachnoid and intracerebral 
hemorrhages, and pulmonary hemorrhage  
Special Senses 
Sudden decrease or loss of hearing  
Other Events 
Nervous 
Seizure, seizure recurrence, anxiety, and transient 
global amnesia 
 
Urogenital 
Prolonged erection, priapism, and hematuria. 
Special Senses 
Diplopia, temporary vision loss/decreased vision, ocular 
redness, ocular burning, ocular swelling, increased 
intraocular pressure, retinal vascular disease, vitreous 
detachment/traction, paramacular edema, and epistaxis. 
Non-arteritic anterior 
ischemic optic 
neuropathy (NAION) 
Decreased vision including permanent loss of vision.  
NAION reported rarely post-marketing in temporal 
association with use of Viagra mostly in patients with 
risk factors including: Low cup to disc ratio, age over 50, 
diabetes, hypertension, coronary heart disease, 
hyperlipidemia, and smoking.  
 
 
 
Table 7.  Incidence of Clinical Worsening and Most Frequent Adverse Events in Daily Dosing of 
Sildenafil and Placebo (dose listed was administered 3 times each day for 12 weeks) 
 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
23 
Dose 
Placebo 
Sildenafil 
Number of Subjects  
(percent Female) 
-- 
n=70 (81%) 
20mg TID 
n=69 (71%) 
40mg TID 
n=67 (70% 
80mg TID 
n=71 (79%) 
Clinical worsening 
7 (10%) 
3 (4%) 
2 (3%) 
 
5 (7%) 
Death   
1 (1%) 
0 
1 (1%) 
2 (3%) 
Hospitalization for pulmonary 
arterial hypertension 
7 (10%) 
2 (3%) 
2 (3%) 
2 (3%) 
Initiation of prostacyclin 
1 (1) 
0 
0 
0 
Initiation of bosentan 
 
0 
0 
1 (1) 
0 
Adverse Events 
Placebo 
Sildenafil 
 
 
20mg TID 
40mg TID 
80mg TID 
Headache                                               
27 (39%) 
32 (46%) 
28 (42%) 
35 (49%) 
Flushing 
 
                     
3 (4%) 
7 (10%) 
6 (9%) 
11 (15%) 
Dyspepsia 
 
 
            
5 (7%) 
9 (13%) 
6 (9%) 
9 (13%) 
Back pain 
 
 
          
8 (11%) 
9 (13%) 
9 (13%) 
9 (8%) 
Diarrhea 
 
 
           
4 (6%) 
6 (9%) 
8 (12%) 
7 (10%) 
Limb pain 
 
 
           
4 (6%) 
5 (7%) 
10 (15%) 
6 (8%) 
Myalgia  
 
 
3 (4%) 
5 (7%) 
4 (6%) 
10 (14%) 
Cough  
 
 
          
4 (6%) 
5 (7%) 
3 (4%) 
6 (8%) 
Epistasis 
 
 
          
1 (1%) 
6 (9%) 
5 (7%) 
3 (4%) 
Pyrexia  
 
            
2 (3%) 
4 (6%) 
2 (3%) 
7 (10%) 
Insomnia 
 
 
          
1 (1%) 
5 (7%) 
4 (6%) 
3 (4%) 
Influenza 
 
 
          
2 (3%) 
4 (6%) 
4 (6%) 
3 (4%) 
Visual disturbance 
0 
0 
3 (4%) 
5 (7%) 
Gastritis 
0 
2 (3%) 
2 (3%) 
3 (4%) 
 
FDA WARNING: There is a potential for cardiac risk of sexual activity in patients with 
preexisting cardiovascular disease.  Therefore, treatments for erectile dysfunction, including 
VIAGRA, should not be generally used in men for whom sexual activity is inadvisable because 
of their underlying cardiovascular status. We expect this will be rare in our study, which will not 
enroll subjects older than 50 years of age. Participants with hypotension, cardiac failure, or 
coronary artery disease with unstable angina are excluded from this study.   
 
8.3 TIME PERIOD AND FREQUENCY FOR EVENT ASSESSMENT AND FOLLOW-
UP 
 
After enrollment into the study, a telephone follow-up will occur every 7 days.  Telephone follow-
up and clinic visits will give physician investigators an opportunity to interface with participants.  
Participants will be instructed to call 911 or go to the nearest emergency room in the event of a 
serious symptom.   Investigators will carry a pager and will be available to the study participants 
for questions or conserns about side effects. Study participants will be cautioned against taking 
medications that may have possible adverse interactions with sildenafil. Licensed physician-
investigators may prescribe medication for headache or other minor side effects.  Otherwise, 
patients will be instructed to seek medical attention from their personnal physician. 
 
 
8.4 
REPORTING PROCEDURES 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
24 
 
8.4.1 ADVERSE EVENT REPORTING  
 
Adverse events will be reported in accordance with Federal requirements. All adverse events, 
serious and non-serious, expected and unexpected, related and unrelated will be tracked by the 
study coordinator and medical monitors. Serious or unexpected adverse events and other 
unanticipated problems will be reported orally as soon as possible and in writing within 7 days if 
life-threatening and within 15 days otherwise to the IRB and FDA. Expected or non-serious 
adverse events will be reported at the time of continuing review. 
 
8.4.2 REPORTING OF PREGNANCY  
 
Although extensive testing in animals has demonstrated no negative effects on the fetus, 
sildenafil has not been studied in pregnant women. Sildenafil is listed as Pregnancy Category B. 
Pregnancy is an exclusion criteria in this study. There is no effect of sildenafil on sperm count or 
motility of sperm in men. If a participant has been enrolled and tests positive preganancy at a 
later visit, she will be withdrawn from the study. 
 
8.5 
STUDY HALTING RULES  
 
Administration of study agent will be halted when three grade 3 AEs determined to be “probably 
related” are reported to the study coordinators and /or study PIs. The PIs will notify the IRB and 
FDA immediately when the third grade 3 event is reported and enrollment screens will stop 
accepting new study participants. The PI will inform the DSMP members within 24 hours of this 
occurrence and will provide the DSMP group with AE listing reports. The DSMP members will 
convene an ad hoc meeting by teleconference or in writing as soon as possible. The DSMP 
members will provide recommendations for proceeding with the study to the study sponsor. The 
PI will inform the FDA of the temporary halt and the disposition of the study. 
 
8.6 
SAFETY OVERSIGHT 
 
Safety oversight will be under the direction of a DSMP composed of individuals with the 
appropriate expertise, including Neurology/Radiology. The DSMP members will only meet to 
discuss reported AEs. A written reported will be submitted to the DSMP group every 6 months. 
At this time, each data element that the DSMP group needs to assess will be clearly defined. 
The DSMP group will provide its input to the PI and IRB. 
 
9 
CLINICAL MONITORING 
 
Roles and Responsibilities 
The PI, Dr. Ding, will be responsible for working with the IRB to ensure the participants’ safety 
on a daily basis. In addition, we assembled independent safety monitors (ISM) as a part of our 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
25 
DSMP to oversee trial safety, data management, analysis and quality assurance. Marco Pinho, 
M.D. (Assistant Professor, UT Southwestern Medical Center), Donald Glass, M.D., Ph.D. 
(Assistant Professor, UT Southwestern Medical Center) and Kimbra Kenney, M.D. (Neurologist, 
Walter Reed National Military Medical Center) will oversee the study protocols, monitor the 
safety of the participants, and ensure data security. Drs. Pinho, Glass, and Kenney (outside 
member) are not associated with the trial and have no conflicts of interest with the study team or 
proposed institutions. Dr. Pinho will be responsible for reviewing protocol adherence, quality 
control, regular data verification and protocol compliance. Over the last 4 years, Dr. Pinho has 
assisted Dr. Gatson on various pilot clinical studies at UT Southwestern Medical Center. His 
role of those studies was to examine computed tomography (CT) and magnetic resonance 
imaging (MRI) to screen for intracranial injuries within research subjects enrolled in Dr. Gatson’s 
clinical studies. Drs. Glass and Kenney will be responsible for monitoring data management, 
analysis and quality assurance by reviewing the data sources, the security measures in place to 
protect data sources (how data will be labelled and stored), and adherence to Good Clinical 
Practice and regulatory requirements. At UT Southwestern Medical Center, Dr. Glass has 
previously served on a number data safety monitoring boards.  
The ISMs will meet with the investigative team at the start of the trial. The study coordinator 
will complete monthly reports detailing the study progress enrollment status, other medications 
taken by the participants during the trial (to screen for concomitant drug use), any adverse 
events (AEs), and any protocol deviations.  
 
Trial Safety 
Throughout the study, the study coordinator and investigators will monitor the participants 
for AEs. The study coordinator will contact the study participants every 7 days to monitor for 
adverse events. To monitor for drug toxicity, at the 2nd visit to UT Southwestern Medical Center 
(day 1-3), 8cc of blood will be collected to determine toxicology, liver function, and coagulation 
after taking the study drug (sildenafil) for 1-3 days. The study participants will be asked to notify 
the study team if planning to take any other drug besides the study drug. The participants will 
also be asked to maintain a daily log of medications taken other than the study drug to monitor 
drug to drug interactions. 
Safety oversight will be under the direction of study PI, medical monitors (Drs. Joseph Minei 
and Christopher Madden) and the research coordinator. A written reported will be submitted to 
the DSMP members every 6 months. The ISMs will only meet to discuss reported AEs. Events 
determined by the PI and co-investigators to be unexpected adverse events involving risks to 
subjects or others will be reported by the contact PI to the IRB and FDA within 7 business days. 
With respect to unexpected adverse events, the contact PI will inform the ISMs within 24 hours 
of this occurrence and will provide the ISMs with AE listing reports. The ISMs will convene an ad 
hoc meeting by teleconference or in person as soon as possible and provide recommendations 
for proceeding with the study to the study sponsor and IRB. The ISM will provide its input in the 
report to the PI and IRB. The contact PI will inform the FDA if there is a temporary or permanent 
halt of the study. All study members will be informed by the contact PI about any unexpected 
adverse events. 
Upon the reporting of unexpected adverse events a participant, the study coordinator will 
collect a blood sample (8cc) to determine blood chemistry and will conduct follow up medical 
monitoring. The Quest Diagnostics laboratory (Dallas, Texas) will perform the biochemical tests. 
The subject information, adverse event report (if any), and research chart will be kept in a 
locked file cabinet in the research office (South Campus H7.126). Only study investigators and 
coordinators will have access to the subject’s file.  
 
 
 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
26 
 
10 
STATISTICAL CONSIDERATIONS  
 
10.1 STATISTICAL AND ANALYTICAL PLANS 
 
STATISTICAL ANALYSIS PLAN 
Study design and randomization scheme 
 
Once eligibility is confirmed, based upon defined inclusion and exclusion criteria, 
randomization will occur within 2 hours of a bout. The placebo-controlled double-blind design 
will diminish concern about predictability of treatment assignments. The unblinded study 
biostatistician will prepare a randomization schedule. Randomization will be 1:1 
sildenafil:placebo, and will be in blocks of 2. Treatment allocation will be determined via a 
computer program that automatically generates random digits. Investigators associated with this 
study will not have access to the randomization schedule. The randomization program will also 
record the assignments to the corresponding boxers in the database and will display the 
assignments on the screen for action by the study coordinators.    
 
Outcomes 
Primary endpoints- The absolute changes in global and regional CBF/CVR to hypercapnia 
and improved symptoms and cognitive performance.  
      Secondary endpoints- Effect of sildenafil on brain biomarkers in blood after injury.  
 
Statistical analyses  
Preliminary analyses: Prior to the formal analyses, we will conduct exploratory data 
analysis by examining the distributions of the key variables using descriptive statistics and 
graphic tools. In particular, baseline variables (demographics, concussion history and injury 
severity characteristics) will be examined to determine whether outliers are present. The 
baseline characteristics of the 100 enrolled boxers/MMA fighters will be compared with 80 
controls using linear regression and two sample testing. Continuous variables (primary and 
secondary outcomes) will be summarized through standard measures of central tendency and 
spread including means, medians, standard deviations and IQRs.  Frequency distributions will 
be calculated for categorical variables (CBF/CVR, post-concussion symptoms, 
neuropsychological measurements). Data transformations will be used if needed to produce 
variables that conform to the distributional assumptions underlying the analytic techniques. Both 
primary and secondary outcomes will be evaluated under the intent-to-treat principle, meaning 
that all available data on all randomized participants, regardless of adherence to the study 
protocol, will be included and analyzed according to the treatment assignment, although 
compliance will be closely monitored via pill counting. Statistical analysis will be performed with 
SAS (SAS Institute, Cary, NC, USA) and R software. 
Primary analyses: Our primary analysis (Aim 1) will be driven by the primary hypothesis that 
administration of single or multiple doses of sildenafil will improve CBF/CVR, lower symptoms 
and improve cognition. Boxplots of CBF and CVR of concussed boxers after sildenafil and 
placebo periods will first be plotted and compared with values at Day 1-3 and 30 post-TBI as 
well as with the 80 controls.  


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
27 
 
Also, we will assess the treatment effect of sildenafil on post-concussive symptoms and 
cognitive performance using two-sample t-test similarly as in the primary aim, but with the 
secondary endpoints of symptoms. On day 1 and 30 after injury we will then calculate the 
difference in CBF/CVR and each of the post-concussive symptom assessments and cognitive 
assessments after the single treatment of sildenafil. Also, we will assess the post-concussion 
correlations of CBF/CVR and cognitive performance by calculating the cross-sectional Pearson 
correlations of CBF/CVR with symptom inventory and neuropsychological CDEs collected at 
Day 1 and 30 after TBI. Correlations will be calculated separately and jointly at each time point, 
and for each of the subdomains of neuropsychological CDEs. Multiple comparisons will be 
adjusted by controlling the false discovery rate (FDR). 
 
Our secondary analyses will consist of assessing the treatment effect of sildenafil therapy on 
brain biomarker levels using two-sample t testing, but with the secondary endpoints of symptoms. 
We will then calculate the difference in brain biomarker levels at the beginning of the sildenafil 
therapy and after the treatment period (Day 30 vs Day 1-3). Scatter plots including both arms will 
be generated based on the calculated differences and two linear regression models with changes 
in brain biomarkers as outcomes, and changes in symptoms as independent variables will be fit 
to assess the association between the recovery of the TBI-related markers. Potential confounders 
such as gender and treatment arm indicator will be adjusted in the model.  
  
Alternative strategies:  
 
For our primary analysis, if CBF or CVR is not normally distributed based as shown in Q-Q 
plot, a nonparametric Wilcoxon rank-sum test will be used instead. And for our secondary 
analysis, if we are not powered to identify correlations of biomarkers with subdomains of 
symptoms and neuropsychological CDEs after multiple comparison correction, we will use 
dimension reduction approaches such as principal component regression (PCR) on CDEs to 
group panels of symptom assessments. The resulting panels of symptoms are selected to 
explain most of the variations across subjects and will be most correlated with brain biomarkers.  
 
Stopping rules 
 
We do not anticipate a stopping rule for efficacy as the primary and secondary endpoints of 
the proposed study are clinically important, but intermediate. Even if we cannot reject the null 
hypothesis for the primary end point, we have multiple secondary endpoints that could still 
benefit our understanding towards the effect of sildenafil on concussed injury. Data collected in 
this study will be used to conduct a power analysis to design and implement the definitive study. 
 
Sensitivity analyses and missing data 
 
Although we do not expect large amount of missing data due to the close monitoring of the 
study implementation and great compliance rate from the past study experiences, we will 
perform sensitivity analyses to assess the potential impact of missing data. Since the analytic 
methods proposed in the primary and secondary aims will base on the missing at random 
(MAR) assumption, we will investigate the amount and patterns of missing data, and their 
influence on the final estimates. We will compare the rate of missing observations between the 
treatment and placebo groups using Fisher’s exact tests. We will also evaluate model estimates 
using complete data only and data with imputed values to see whether the results suggest bias 
in analysis of the available data. For possible missing values that are “non-ignorable”, we will 
utilize methods that jointly model the missing mechanism and the time-dependent outcomes to 
conduct valid statistical inference. In particular, shared parameter models, pattern-mixture 
models and potentially joint modeling of survival and longitudinal analysis methods could be 
used to assess potential impact of missing data. Shared parameter models link the outcome 
and missing probabilities using latent variables (random effects), and a logistic regression will 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
28 
be used to estimate the probability of missing at each time point. While pattern-mixture models 
allow separate models for observations with different patterns of missingness. Results obtained 
from the shared parameter and pattern-mixture models will be compared to the estimates from 
the analysis under the MAR assumption. Statistical software including SAS and R will be used 
for the analysis.   
 
 Power analysis and sample size justification 
 
We conducted a power analysis based on the primary endpoints of change in CVR and CBF 
and correlation of CBF/CVR and symptoms/cognition. Based on the preliminary results, we 
assume the average changes in CVR between treatment and placebo has an effect size of 0.86. 
With 50 concussed boxers in each arm, assuming that the correlation between the outcome 
measures at Day 1-3 and 30 is 0.2, we will achieve 80% power to detect difference in CVR 
changes comparing sildenafil and placebo effects. If the correlation is 0.5 among outcome 
measures at all time-points, then with 80% power we only need 34 concussed boxers in each 
arm. Table 1 demonstrates the needed sample size under a range of effect sizes and within-
subject correlations. To understand the correlation between the CVR and post-concussive 
symptoms among the 50 enrolled boxers (for each group) assessed at three time points, we will 
have 82.9% power to detect a correlation of 0.4 based on the preliminary results in Table 1 with 
95% confidence level. 
 
 
 
 
 
 
 
 
 
 
 
Table 1: Sample size for each treatment and placebo group under a range of effect sizes and 
within-subject correlations to achieve 80% power. 
 
Reference: 
1. 
Liu GF, Lu K, Mogg R, Mallick M, Mehrotra DV. Should baseline be a covariate or 
dependent variable 
Correlation between 3, time-points (rho) 
0 
0.2 
0.3 
0.5 
0.6 
0.7 
0.8 
Corresponding SD 
1.414 
1.265 
1.183 
1 
0.894 
0.775 
0.632 
Effect size 
Sample size needed  
0.7 
46 
38 
33 
25 
21 
16 
12 
0.86 
32 
26 
23 
18 
15 
12 
9 
1 
24 
20 
18 
14 
12 
10 
8 
1.2 
18 
15 
14 
11 
9 
8 
6 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
29 
            in analyses of change from baseline in clinical trials? Statistics in medicine 
2009;28:2509-30 
2. 
Verbeke G, Molenberghs G. Linear Mixed Models for Longitudinal Data2009. 
3. 
Molenberghs G, Thijs H, Jansen I, et al. Analyzing incomplete longitudinal clinical trial 
data. Biostatistics 2004;5:445-64 
4. 
Verbeke G, Molenberghs G, Thijs H, Lesaffre E, Kenward MG. Sensitivity analysis for 
nonrandom 
            dropout: a local influence approach. Biometrics 2001;57:7-14 
5.    
Liang KY, Heagerty P, Diggle PJ, Zeger SL. Analysis of longitudinal data. Oxford 
Statistical Science Series, 2002. 
6.   
Ramsay JO and Silverman BW. Functional data analysis. Springer Series in Statistics, 
2005. 
7.  
Shou H., Zipunnikov V, Crainiceanu CM, and Greven S. Structured functional principal 
component  
            analysis. Biometrics, 2015. 71(1): p. 247-57.  
 
 
10.2 MEASURES TO MINIMIZE BIAS 
 
10.2.1 ENROLLMENT/ RANDOMIZATION/ MASKING PROCEDURES 
 
Recruitment Methods and Consenting Process: 
At the baseline visit, the participants will be consented to participate in the study. After 
participating in the boxing match, the enrolled boxers will be re-screened and if the boxer has a 
Rivermead symptom score > 1 on at least 3 items from the Rivermead Post-Concussion 
Questionnaire or has greater than 25 blows to the head, the participant will be informed of their 
eligibility to participate in the study and the potential risks associated with this clinical trial. 
 A copy of the signed consent form will be provided to the participant/family, and one 
copy will remain in a locked storage facility. Both women and minorities will be enrolled in this 
study. Due to the study population, children will not be enrolled in this study. Previously, we 
have enrolled 125 boxers from the North Texas area to participate in both observational and 
interventional clinical trials. Recently we completed a Department of Defense (DOD) 
observational study aimed at measuring early brain biomarkers of injury in professional boxers. 
We identified numerous early predictors of outcome in these athletes. Our dropout rate is very 
low and previously the boxers were compliant with the study procedures (self-administering 
study medication, neuropsychological testing, MRI procedures). We expect a dropout rate of 10-
20% and will enroll a total of 110-120 boxers to complete the proposed studies.  
 
Drug Treatment and Randomization: 
We will enroll 100 concussed boxers/MMA fighters using a double-blind, placebo-
controlled design.  The athletes will be randomized at a 1:1 ratio to either placebo or sildenafil 
for single or multiple doses (once-a-day for 14 days).  


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
30 
A randomization schedule will be prepared by the study statistician. Investigators 
associated with this study will not have access to the schedule. The PI, study team, and 
participants will be blinded. 
 
 
 
11 
SOURCE DOCUMENTS AND ACCESS TO SOURCE DATA/DOCUMENTS 
 
In compliance with ICH E6, regulatory and institutional requirements for the protection of 
confidentiality of participants, and the NIH, following enrollment into the clinical trial, the 
participant will be assigned a study numer. Also, all documents (information form, medical 
history, concussion history, neuropsychological and symptom forms) and imaging information 
collected during the course of the study will be placed into the participant study chart. The study 
chart will also contain a copy of the signed consent and HIPAA forms. The subject’s research 
chart will be kept in a locked file cabinet in the research office (South Campus H7.126). Only 
study investigators and coordinators will have access to the subject’s file.  
 
 
 
12 
QUALITY ASSURANCE AND QUALITY CONTROL 
 
QC procedures will be implemented beginning with the data entry system and data QC checks 
that will be run on the REDCap database will be generated. Any missing data or data 
anomalies will be communicated in writing to the study PIs and DSMP group. Following written 
SOPs, the monitors will verify that the clinical trial is conducted and data are generated, 
documented (recorded), and reported in compliance with the protocol, GCP, and the 
applicable regulatory requirements (e.g., Good Laboratory Practices (GLP), Good 
Manufacturing Practices (GMP)). The investigational site will provide direct access to all trial 
related sites, source data/documents, and reports for the purpose of monitoring and auditing 
by the irb, FDA, and NIH. 
 
 
13 
ETHICS/PROTECTION OF HUMAN SUBJECTS  
 
13.1 ETHICAL STANDARD  
 
The investigator will ensure that this study is conducted in full conformity with Regulations for 
the Protection of Human Subjects of Research codified in 45 CFR Part 46, 21 CFR Part 50, 21 
CFR Part 56, and/or the ICH E6. 
 
 
 
13.2 INSTITUTIONAL REVIEW BOARD  
 
The protocol, informed consent form(s), recruitment materials, and all participant materials will 
be submitted to the IRB for review and approval. Approval of both the protocol and the consent 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
31 
form must be obtained before any participant is enrolled. Any amendment to the protocol will 
require review and approval by the IRB before the changes are implemented to the study. All 
changes to the consent form will be IRB approved; a determination will be made regarding 
whether previously consented participants need to be re-consented. 
 
 
 
 
13.3 INFORMED CONSENT PROCESS  
 
13.3.1 CONSENT/ASSENT AND OTHER INFORMATIONAL DOCUMENTS 
PROVIDED TO PARTICIPANTS 
 
Consent forms describing in detail the study agent, study procedures, and risks will be given to 
the participant and written documentation of informed consent will be required prior to starting 
intervention/administering study product.  
 
 
 
13.3.2 CONSENT PROCEDURES AND DOCUMENTATION 
 
Informed consent is a process that is initiated prior to the individual agreeing to participate in 
the study and continues throughout the individual’s study participation. Extensive discussion 
of risks and possible benefits of participation will be provided to the participants and their 
families. Consent forms will be IRB-approved and the participant will be asked to read and 
review the document. The investigator/study coordinator will explain the research study to 
the participant and answer any questions that may arise. All participants will receive a verbal 
explanation in terms suited to their comprehension of the purposes, procedures, and 
potential risks of the study and of their rights as research participants. Participants will have 
the opportunity to carefully review the written consent form and ask questions prior to 
signing. The participants should have the opportunity to discuss the study with their 
surrogates or think about it prior to agreeing to participate. The participant will sign the 
informed consent document prior to any procedures being done specifically for the study. 
The participants may withdraw consent at any time throughout the course of the trial. A copy 
of the informed consent document will be given to the participants for their records.  
 
 
 
13.4 PARTICIPANT AND DATA CONFIDENTIALITY  
 
Participant confidentiality is strictly held in trust by the participating investigators, their staff, and 
the sponsor(s) and their agents. This confidentiality is extended to cover 
MRI/neuropsychological testing, and collection and testing of biological samples in addition to 
the clinical information relating to participants. Therefore, the study protocol, documentation, 
data, and all other information generated will be held in strict confidence. No information 
concerning the study or the data will be released to any unauthorized third party without prior 
written approval of the PI and UTSWMC.  
 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
32 
The representatives of the IRB may inspect all documents and records required to be 
maintained by the investigator, including but not limited to, medical records (office, clinic, or 
hospital) and pharmacy records for the participants in this study. The PIs will permit access to 
such records.  
 
The study participant’s contact information will be securely stored for internal use during the 
study. At the end of the study, all records will continue to be kept in a secure location for as 
long a period as dictated by the IRB. Study participant research data, which is for purposes of 
statistical analysis and scientific reporting, will be transmitted to and stored in a locked cabinet 
at UTSWMC. This will not include the participant’s contact or identifying information. Rather, 
individual participants and their research data will be identified by a unique study identification 
number. The study data entry and study management systems used by the UTSWMC 
research staff will be secured and password protected. At the end of the study, all study 
databases will be de-identified and archived at UTSWMC.  
 
 
 
 
 
13.4.1 RESEARCH USE OF STORED HUMAN SAMPLES,SPECIMENS OR DATA 
 
 
• 
 Intended Use: Samples and data collected under this protocol may be used to study the 
efficacy of sildenafil at increasing CBF/CVR, reducing symptoms, and improving cognition. No 
genetic testing will be performed.  
• 
Storage: Access to stored samples will be limited to the research team. Samples and 
data will be stored using deidentified subject codes assigned by the investigators. Data will be 
kept in password-protected computers. Only investigators will have access to the samples and 
data. All documents pertaining to the study will be stored under lock and key in secured rooms 
accessible only to the study personnel. 
• 
 
Tracking: Data will be tracked using REDCap. Disposition at the completion of the study: All 
stored samples will be stored at UTSWMC. Study participants who request destruction of 
samples will be notified of compliance with such request and all supporting details will be 
maintained for tracking.  
 
 
 
13.5 FUTURE USE OF STORED SPECIMENS  
 
Data collected for this study will be analyzed and stored at UTSWMC. After the study is 
completed, the de-identified, archived data will be transmitted to and stored at the UTSWMC 
TBI Data Repository, under the supervision of Kan Ding, for use by other researchers 
including those outside of the study. Permission to transmit data to the UTSWMC TBI Data 
Repository will be included in the informed consent.  


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
33 
 
With the participant’s approval and as approved by local IRBs, de-identified biological samples 
will be stored at the UTSWMC TBI Data Repository with the same goal as the sharing of data 
with approved entities. The UTSWMC TBI Data Repository will also be provided with a code-link 
that will allow linking the biological specimens with the phenotypic data from each participant, 
maintaining the masking of the identity of the participant.  
 
During the conduct of the study, an individual participant can choose to withdraw consent 
to have biological specimens stored for future research. However, withdrawal of consent 
with regard to biosample storage will not be possible after the study is completed.  
When the study is completed, access to study data and/or samples will be provided through the 
UTSWMC TBI Data Repository. 
 
 
 
14 
DATA HANDLING AND RECORD KEEPING  
 
14.1 DATA COLLECTION AND MANAGEMENT RESPONSIBILITIES  
 
We will follow data collection practices recommended by the NIH NINDS Common Data 
Elements. (1) Data entry and management:  A database will be developed using REDCap. All 
data will be double entered.  A comparison will be run between the primary and secondary 
entries to detect inconsistencies and data entry errors. Data will be routinely audited.  If any 
systematic errors are found, data entry will stop and the data management system will be 
evaluated.  (2) Data security: All data (e.g., survey, recordings, and electronic files) will be 
identified by alpha-numeric codes only, consent forms will be maintained separately from the 
data, data will be password protected, and all data will be stored in locked cabinets in lab 
offices.  Only members of the research team will have access to these files.  
 
 
14.2 STUDY RECORDS RETENTION  
 
Study documents will be retained for a minimum of 3 years after the completion of the study.  
 
 
 
14.3 PROTOCOL DEVIATIONS  
 
A protocol deviation is any noncompliance with the clinical trial protocol, GCP, or MOP 
requirements. The noncompliance may be either on the part of the participant, the investigator, 
or the study site staff. If deviations occur, corrective actions will be developed by study PIs and 
implemented promptly.  
 
These practices are consistent with ICH E6:  
• 
4.5 Compliance with Protocol, sections 4.5.1, 4.5.2, and 4.5.3  
• 
5.1 Quality Assurance and Quality Control, section 5.1.1  
• 
5.20 Noncompliance, sections 5.20.1, and 5.20.2.  


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
34 
 
It is the responsibility of our research group to use continuous vigilance to identify and report 
deviations within 7 working days of identification of the protocol deviation, or within 7 working 
days of the scheduled protocol-required activity. All deviations must be addressed in study 
source documents. Protocol deviations must be sent to our IRB.  The site PI/study staff will be 
responsible for knowing and adhering to the IRB requirements. Further details about the 
handling of protocol deviations will be included in the MOP. 
 
 
 
14.4 PUBLICATION AND DATA SHARING POLICY 
To be considerd for publication in scientific journals, this clinical trial will be registered with 
ClinicalTrials.gov prior to initiaited any study related activities. 
Resource Sharing: MRI data, neuropsychological data, and blood/saliva samples will be 
catalogued and stored for future study.  Beyond publication of results in peer-reviewed journals 
and presentations at national meetings, Dr. Ding will make available data/samples to other 
investigators as a resource.  All data requests will be considered by a Scientific Advisory Panel 
that will be established to determine access to data developed by the proposed study as well as 
subsequent ancillary studies.  This Scientific Advisory Panel will be comprised of senior 
researchers and clinicians, including Drs. Christopher Madden MD andKan Ding MD,.  No data 
that enable identification of individual patients will be collected or shared.  All data will be 
stripped of patient identifiers upon collection; further de-identification to comply with HIPAA and 
Institutional Review Board regulations will not be necessary prior to sharing of resources with 
other investigators.  Further, summary results will be posted on a laboratory website that will 
also provide access to data dictionaries, protocols, and ancillary study proposal forms.  This 
website will describe the procedure for requesting data and proposing ancillary studies through 
the Scientific Advisory Panel.   
 
15 
STUDY ADMINISTRATION 
 
15.1 STUDY LEADERSHIP 
 
The Steering Committee will govern the conduct of the study. The Steering Committee will be 
composed of the study PI and Dr. Christopher Madden (Medical Monitor). The Steering 
Committee will meet in person at least annually. 
 
 
 
16 
CONFLICT OF INTEREST POLICY 
 
The independence of this study from any actual or perceived influence, such as by the 
pharmaceutical industry, is critical. Therefore any actual conflict of interest of persons who 
have a role in the design, conduct, analysis, publication, or any aspect of this trial will be 
disclosed and managed. Furthermore, persons who have a perceived conflict of interest will be 
required to have such conflicts managed in a way that is appropriate to their participation in the 
trial. The study leadership in conjunction with UTSWMC has established policies and 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
35 
procedures for all study group members to disclose all conflicts of interest and will establish a 
mechanism for the management of all reported dualities of interest. 
 
 
 
17  
LITERATURE REFERENCES  
1. 
Adamides AA, Winter CD, Lewis PM, Cooper DJ, Kossmann T, Rosenfeld JV. Current controversies in the 
management of patients with severe traumatic brain injury. ANZ journal of surgery. 2006;76(3):163-74. 
2. 
Sahuquillo J, Arikan F. Decompressive craniectomy for the treatment of refractory high intracranial 
pressure in traumatic brain injury. The Cochrane database of systematic reviews. 2006(1):CD003983. 
3. 
Maxwell WL, Irvine A, Adams JH, Graham DI, Gennarelli TA. Response of cerebral microvasculature to 
brain injury. J Pathol. 1988;155(4):327-35. 
4. 
Park E, Bell JD, Siddiq IP, Baker AJ. An analysis of regional microvascular loss and recovery following two 
grades of fluid percussion trauma: a role for hypoxia-inducible factors in traumatic brain injury. Journal of cerebral 
blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism. 
2009;29(3):575-84. 
5. 
Baranova AI, Wei EP, Ueda Y, Sholley MM, Kontos HA, Povlishock JT. Cerebral vascular responsiveness 
after experimental traumatic brain injury: the beneficial effects of delayed hypothermia combined with superoxide 
dismutase administration. Journal of neurosurgery. 2008;109(3):502-9. 
6. 
Gao G, Oda Y, Wei EP, Povlishock JT. The adverse pial arteriolar and axonal consequences of traumatic 
brain injury complicated by hypoxia and their therapeutic modulation with hypothermia in rat. Journal of cerebral 
blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism. 
2010;30(3):628-37. 
7. 
Schwarzmaier SM, Kim SW, Trabold R, Plesnila N. Temporal profile of thrombogenesis in the cerebral 
microcirculation after traumatic brain injury in mice. Journal of neurotrauma. 2010;27(1):121-30. 
8. 
Rodriguez-Baeza A, Reina-de la Torre F, Poca A, Marti M, Garnacho A. Morphological features in human 
cortical brain microvessels after head injury: a three-dimensional and immunocytochemical study. Anat Rec A 
Discov Mol Cell Evol Biol. 2003;273(1):583-93. 
9. 
Wei EP, Dietrich WD, Povlishock JT, Navari RM, Kontos HA. Functional, morphological, and metabolic 
abnormalities of the cerebral microcirculation after concussive brain injury in cats. Circ Res. 1980;46(1):37-47. 
10. 
Wei EP, Hamm RJ, Baranova AI, Povlishock JT. The long-term microvascular and behavioral consequences 
of experimental traumatic brain injury after hypothermic intervention. Journal of neurotrauma. 2009;26(4):527-37. 
11. 
Stein SC, Graham DI, Chen XH, Smith DH. Association between intravascular microthrombosis and cerebral 
ischemia in traumatic brain injury. Neurosurgery. 2004;54(3):687-91; discussion 91. 
12. 
Glushakova OY, Johnson D, Hayes RL. Delayed increases in microvascular pathology after experimental 
traumatic brain injury are associated with prolonged inflammation, blood-brain barrier disruption, and progressive 
white matter damage. Journal of neurotrauma. 2014;31(13):1180-93. 
13. 
Dietrich WD, Alonso O, Halley M. Early microvascular and neuronal consequences of traumatic brain 
injury: a light and electron microscopic study in rats. Journal of neurotrauma. 1994;11(3):289-301. 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
36 
14. 
Boolell M, Allen MJ, Ballard SA, Gepi-Attee S, Muirhead GJ, Naylor AM, et al. Sildenafil: an orally active 
type 5 cyclic GMP-specific phosphodiesterase inhibitor for the treatment of penile erectile dysfunction. Int J Impot 
Res. 1996;8(2):47-52. 
15. 
Boolell M, Gepi-Attee S, Gingell JC, Allen MJ. Sildenafil, a novel effective oral therapy for male erectile 
dysfunction. Br J Urol. 1996;78(2):257-61. 
16. 
Zhang R, Wang Y, Zhang L, Zhang Z, Tsang W, Lu M, et al. Sildenafil (Viagra) induces neurogenesis and 
promotes functional recovery after stroke in rats. Stroke. 2002;33(11):2675-80. 
17. 
Li L, Jiang Q, Zhang L, Ding G, Gang Zhang Z, Li Q, et al. Angiogenesis and improved cerebral blood flow in 
the ischemic boundary area detected by MRI after administration of sildenafil to rats with embolic stroke. Brain 
Res. 2007;1132(1):185-92. 
18. 
Pifarre P, Prado J, Giralt M, Molinero A, Hidalgo J, Garcia A. Cyclic GMP phosphodiesterase inhibition 
alters the glial inflammatory response, reduces oxidative stress and cell death and increases angiogenesis following 
focal brain injury. J Neurochem. 2010;112(3):807-17. 
19. 
Chen XM, Wang NN, Zhang TY, Wang F, Wu CF, Yang JY. Neuroprotection by sildenafil: neuronal networks 
potentiation in acute experimental stroke. CNS Neurosci Ther. 2014;20(1):40-9. 
20. 
Zhang RL, Chopp M, Roberts C, Wei M, Wang X, Liu X, et al. Sildenafil enhances neurogenesis and 
oligodendrogenesis in ischemic brain of middle-aged mouse. PLoS One. 2012;7(10):e48141. 
21. 
Ding G, Jiang Q, Li L, Zhang L, Zhang Z, Lu M, et al. Longitudinal magnetic resonance imaging of sildenafil 
treatment of embolic stroke in aged rats. Stroke. 2011;42(12):3537-41. 
22. 
Alderson P, Roberts I. Corticosteroids for acute traumatic brain injury. The Cochrane database of 
systematic reviews. 2005(1):CD000196. 
23. 
Wakai A, Roberts I, Schierhout G. Mannitol for acute traumatic brain injury. The Cochrane database of 
systematic reviews. 2005(4):CD001049. 
24. 
Carroll LJ, Cassidy JD, Cancelliere C, Cote P, Hincapie CA, Kristman VL, et al. Systematic review of the 
prognosis after mild traumatic brain injury in adults: cognitive, psychiatric, and mortality outcomes: results of the 
International Collaboration on Mild Traumatic Brain Injury Prognosis. Archives of physical medicine and 
rehabilitation. 2014;95(3 Suppl):S152-73. 
25. 
Selassie AW, Zaloshnja E, Langlois JA, Miller T, Jones P, Steiner C. Incidence of long-term disability 
following traumatic brain injury hospitalization, United States, 2003. The Journal of head trauma rehabilitation. 
2008;23(2):123-31. 
26. 
Dikmen SS, Machamer JE, Powell JM, Temkin NR. Outcome 3 to 5 years after moderate to severe 
traumatic brain injury. Archives of physical medicine and rehabilitation. 2003;84(10):1449-57. 
27. 
Burke MJ, Fralick M, Nejatbakhsh N, Tartaglia MC, Tator CH. In search of evidence-based treatment for 
concussion: characteristics of current clinical trials. Brain injury. 2015;29(3):300-5. 
28. 
Oda Y, Gao G, Wei EP, Povlishock JT. Combinational therapy using hypothermia and the immunophilin 
ligand FK506 to target altered pial arteriolar reactivity, axonal damage, and blood-brain barrier dysfunction after 
traumatic brain injury in rat. Journal of cerebral blood flow and metabolism : official journal of the International 
Society of Cerebral Blood Flow and Metabolism. 2011;31(4):1143-54. 
29. 
Bouma GJ, Muizelaar JP, Choi SC, Newlon PG, Young HF. Cerebral circulation and metabolism after severe 
traumatic brain injury: the elusive role of ischemia. Journal of neurosurgery. 1991;75(5):685-93. 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
37 
30. 
Adelson PD, Srinivas R, Chang Y, Bell M, Kochanek PM. Cerebrovascular response in children following 
severe traumatic brain injury. Childs Nerv Syst. 2011;27(9):1465-76. 
31. 
Marion DW, Darby J, Yonas H. Acute regional cerebral blood flow changes caused by severe head injuries. 
Journal of neurosurgery. 1991;74(3):407-14. 
32. 
Wintermark M, van Melle G, Schnyder P, Revelly JP, Porchet F, Regli L, et al. Admission perfusion CT: 
prognostic value in patients with severe head trauma. Radiology. 2004;232(1):211-20. 
33. 
da Costa L, van Niftrik CB, Crane D, Fierstra J, Bethune A. Temporal Profile of Cerebrovascular Reactivity 
Impairment, Gray Matter Volumes, and Persistent Symptoms after Mild Traumatic Head Injury. Front Neurol. 
2016;7:70. 
34. 
Hatefi M, Behzadi S, Dastjerdi MM, Ghahnavieh AA, Rahmani A, Mahdizadeh F, et al. Correlation of 
Homocysteine with Cerebral Hemodynamic Abnormality, Endothelial Dysfunction Markers, and Cognition 
Impairment in Patients with Traumatic Brain Injury. World Neurosurg. 2017;97:70-9. 
35. 
Wang Y, Nelson LD, LaRoche AA, Pfaller AY, Nencka AS, Koch KM, et al. Cerebral Blood Flow Alterations in 
Acute Sport-Related Concussion. Journal of neurotrauma. 2016;33(13):1227-36. 
36. 
Wang Y, West JD, Bailey JN, Westfall DR, Xiao H, Arnold TW, et al. Decreased cerebral blood flow in 
chronic pediatric mild TBI: an MRI perfusion study. Dev Neuropsychol. 2015;40(1):40-4. 
37. 
Maugans TA, Farley C, Altaye M, Leach J, Cecil KM. Pediatric sports-related concussion produces cerebral 
blood flow alterations. Pediatrics. 2012;129(1):28-37. 
38. 
Bartnik-Olson BL, Holshouser B, Wang H, Grube M, Tong K, Wong V, et al. Impaired neurovascular unit 
function contributes to persistent symptoms after concussion: a pilot study. Journal of neurotrauma. 
2014;31(17):1497-506. 
39. 
Bailey DM, Jones DW, Sinnott A, Brugniaux JV, New KJ, Hodson D, et al. Impaired cerebral haemodynamic 
function associated with chronic traumatic brain injury in professional boxers. Clin Sci (Lond). 2013;124(3):177-89. 
40. 
Oertel M, Boscardin WJ, Obrist WD, Glenn TC, McArthur DL, Gravori T, et al. Posttraumatic vasospasm: 
the epidemiology, severity, and time course of an underestimated phenomenon: a prospective study performed in 
299 patients. J Neurosurg. 2005;103(5):812-24. 
41. 
Gardner AJ, Tan CO, Ainslie PN, van Donkelaar P, Stanwell P, Levi CR, et al. Cerebrovascular reactivity 
assessed by transcranial Doppler ultrasound in sport-related concussion: a systematic review. Br J Sports Med. 
2015;49(16):1050-5. 
42. 
Lee JK, Kibler KK, Benni PB, Easley RB, Czosnyka M, Smielewski P, et al. Cerebrovascular reactivity 
measured by near-infrared spectroscopy. Stroke. 2009;40(5):1820-6. 
43. 
Rodriguez Merzagora AC, Izzetoglu M, Onaral B, Schultheis MT. Verbal working memory impairments 
following traumatic brain injury: an fNIRS investigation. Brain Imaging Behav. 2014;8(3):446-59. 
44. 
Zweifel C, Castellani G, Czosnyka M, Carrera E, Brady KM, Kirkpatrick PJ, et al. Continuous assessment of 
cerebral autoregulation with near-infrared spectroscopy in adults after subarachnoid hemorrhage. Stroke. 
2010;41(9):1963-8. 
45. 
Zweifel C, Castellani G, Czosnyka M, Helmy A, Manktelow A, Carrera E, et al. Noninvasive monitoring of 
cerebrovascular reactivity with near infrared spectroscopy in head-injured patients. J Neurotrauma. 
2010;27(11):1951-8. 


Sildenafil Treatment for Chronic Traumatic Microvascular Injuries 
 
Version 2.0 
Protocol UT-7529 
1 April  2018 
STU032018-063, Ding, FormA-ResearchProtocol, Mod_6, 11-25-19 (1) NIH-FDA Clinical Trial Protocol 
v1.0 
 
38 
46. 
Attwell D, Iadecola C. The neural basis of functional brain imaging signals. Trends Neurosci. 
2002;25(12):621-5. 
47. 
Wells JA, Christie IN, Hosford PS, Huckstepp RT, Angelova PR, Vihko P, et al. A critical role for purinergic 
signalling in the mechanisms underlying generation of BOLD fMRI responses. The Journal of neuroscience : the 
official journal of the Society for Neuroscience. 2015;35(13):5284-92. 
48. 
Teschemacher AG, Gourine AV, Kasparov S. A Role for Astrocytes in Sensing the Brain Microenvironment 
and Neuro-Metabolic Integration. Neurochemical research. 2015;40(12):2386-93. 
49. 
Ellis MJ, Ryner LN, Sobczyk O, Fierstra J, Mikulis DJ, Fisher JA, et al. Neuroimaging Assessment of 
Cerebrovascular Reactivity in Concussion: Current Concepts, Methodological Considerations, and Review of the 
Literature. Front Neurol. 2016;7:61. 
50. 
Ghofrani HA, Osterloh IH, Grimminger F. Sildenafil: from angina to erectile dysfunction to pulmonary 
hypertension and beyond. Nat Rev Drug Discov. 2006;5(8):689-702. 
51. 
Galie N, Ghofrani HA, Torbicki A, Barst RJ, Rubin LJ, Badesch D, et al. Sildenafil citrate therapy for 
pulmonary arterial hypertension. N Engl J Med. 2005;353(20):2148-57. 
52. 
Wirostko BM, Tressler C, Hwang LJ, Burgess G, Laties AM. Ocular safety of sildenafil citrate when 
administered chronically for pulmonary arterial hypertension: results from phase III, randomised, double masked, 
placebo controlled trial and open label extension. BMJ. 2012;344:e554. 
53. 
Rosengarten B, Schermuly RT, Voswinckel R, Kohstall MG, Olschewski H, Weissmann N, et al. Sildenafil 
improves dynamic vascular function in the brain: studies in patients with pulmonary hypertension. Cerebrovascular 
diseases. 2006;21(3):194-200. 
54. 
Diomedi M, Sallustio F, Rizzato B, Ferrante F, Leone G, Spera E, et al. Sildenafil increases cerebrovascular 
reactivity: a transcranial Doppler study. Neurology. 2005;65(6):919-21. 
55. 
Bozgeyik Z, Berilgen S, Ozdemir H, Tekatas A, Ogur E. Evaluation of the effects of sildenafil citrate (viagra) 
on vertebral artery blood flow in patients with vertebro-basilar insufficiency. Korean J Radiol. 2008;9(6):477-80. 
56. 
Kruuse C, Thomsen LL, Jacobsen TB, Olesen J. The phosphodiesterase 5 inhibitor sildenafil has no effect on 
cerebral blood flow or blood velocity, but nevertheless induces headache in healthy subjects. Journal of cerebral 
blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism. 
2002;22(9):1124-31. 
57. 
Kruuse C, Hansen AE, Larsson HB, Lauritzen M, Rostrup E. Cerebral haemodynamic response or excitability 
is not affected by sildenafil. Journal of cerebral blood flow and metabolism : official journal of the International 
Society of Cerebral Blood Flow and Metabolism. 2009;29(4):830-9. 
58. 
NINDS. TRAUMATIC BRAIN INJURY (TBI) CDE STANDARDS 2010 [Available from: 
http://www.nindscommondataelements.org/UnderConst.aspx?nextform=Traumatic%20Brain%20Injury%20(TBI)%
20CDE%20Standards. 
59. 
Hedeker DG GR. Longitudinal Data Analysis: Wiley-Interscience; 2006. 
60. 
Littell R, Milliken GA, Stroup WW, Wolfinger RD, Schabenberger O. SAS for Mixed Models. 2nd ed. 
Cary, NC: SAS Institute Inc. ; 2006.