Treatment of Adult Patients With Hemoglobin SC Disease
Phase: PHASE2
Conditions: Hemoglobin SC Disease
Sponsor: Baylor College of Medicine

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)\
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
1
TREATMENT OF ADULT PATIENTS WITH HEMOGLOBIN SC DISEASE
Principal Investigator
Vivien Sheehan MD, PhD1
Co-Investigators
Modupe Idowu, MD2
Harinder Juneja, MD2
Sergey Shevkoplyas, PhD3
Mark Udden, MD4
Premal Lulla, MBBS4
Iberia Romina Sosa4
Martha Mims, MD4
Bogdan Dinu, MD1
Statistician
Charles Minard, PhD5
1Hematology Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
2Hematology/Oncology, Department of Internal Medicine, University of Texas Houston,
Houston, Texas
3Department of Biomedical Engineering, University of Houston, Houston, Texas
4 Department of Medicine - Hematology and Oncology, Baylor College of Medicine, Houston,
Texas
5Baylor College of Medicine Dan L. Duncan Institute for Clinical and Translational Research

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
2
Abstract
Decades of observational data, including landmark natural history studies from the
Cooperative Study of Sickle Cell Disease (CSSCD), have documented that sickle cell disease
(SCD) is a severe, debilitating hematological disorder. Hydroxyurea has emerged as an
excellent therapeutic agent for the pharmacological induction of HbF in patients with SCD, due
to its ease of oral administration, modest toxicity profile, and clinical efficacy for preventing
acute vaso-occlusive events. However, all completed clinical trials have excluded patients with
hemoglobin SC (HbSC), restricting the inclusion criteria to patients with HbSS or HbS0 disease.
HbSC differs significantly in pathophysiology from HbSS, as HbC does not sickle, but instead
causes cellular dehydration which potentiates sickling of HbS. HbSC patients demonstrate a
wide variability of clinical courses and a rate of life threatening complications much higher than
the general population.1 Many severely affected HbSC patients have been placed on
hydroxyurea on a case by case basis,2,3 but there is no large scale prospective data on safety or
efficacy of hydroxyurea in this subset of SCD patients.
The primary objective of this phase II clinical trial is to treat symptomatic HbSC patients
prospectively with hydroxyurea to maximum tolerated dose (MTD), and monitor for improvement
using the Adult QLTM 3.0 Sickle Cell Disease Module by comparing scores at entry and after 6
months of hydroxyurea therapy at maximum tolerated dose.
Secondary objectives for this trial are the following:

Effect of hydroxyurea on the following laboratory values:
o
Whole blood viscosity
o
Red cell density
o
Fetal hemoglobin (HbF) levels
o
Mean corpuscular volume (MCV)
o
Mean corpuscular hemoglobin concentration (MCHC)
o
Hemoglobin (Hb) levels
o
Absolute reticulocyte count (ARC)
o
Absolute neutrophil count (ANC)
o
Liver function tests (LFT)
o
Creatinine
o
Lactate dehydrogenase (LDH)
o
Unconjugated bilirubin (u.bili) levels
o
Microalbuminuria as measured by routine urinalysis (UA)
Patients with an AdultQLTM 3.0 Sickle Cell Disease Module demonstrating less than a 10
point improvement after 6 months of hydroxyurea therapy at MTD will be offered therapeutic
phlebotomy. Clinical improvement on this second line therapy will be assessed with the
AdultQLTM 3.0 Sickle Cell Disease Module as well.
Genomic analysis of variants associated with HbF response and disease related
complications. Sequencing will be performed by whole exome sequencing (WES) and
traditional sequencing as indicated.

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
3
This study will enroll patients with HbSC disease from 18 through 69 years of age, who have
evidence of disease-related complications or an AdultQLTM 3.0 Sickle Cell Disease Module
score of 80 or lower
Table of Contents
Study Abstract………………………………………………….……………………..…..2
1.0
OBJECTIVES
1.1
Primary Objectives.........................................................................................4
1.2
Secondary Objectives ....................................................................................4
2.0
BACKGROUND AND RATIONALE..............................................................4
2.1
HbSC disease................................................................................................4
2.2
Role of viscosity on the pathophysiology of HbSC disease ............................5
2.3
Hydroxyurea Therapy for HbSC disease: HbF response................................5
2.4
Effect of hydroxyurea on whole blood viscosity………………………………….6
2.5
Variability of hydroxyurea response in sickle cell disease………………………7
2.6
Treatment rationale……………………………………………….…………………7
2.7
AdultQLTM 3.0 Sickle Cell Disease Module ..................................................7
3.0
RESEARCH PARTICIPANT ELIGIBILITY CRITERIA
AND STUDY ENROLLMENT .......................................................................7
3.1
Inclusion Criteria ............................................................................................7
3.2
Exclusion Criteria ...........................................................................................8
3.3
Research Participant Recruitment and Screening ..........................................8
3.4
Enrollment on Study.......................................................................................8
4.0
STUDY DESIGN AND METHODS ...............................................................9
4.1
Study Design.................................................................................................9
4.2
Methods........................................................................................................9
5.0
CLINICAL AND LABORATORY EVALUATIONS..........................................10
5.1
Special Instructions for Evaluations................................................................13
5.2
Medical Record Review..................................................................................13
5.3
Off-Study Evaluations ....................................................................................14
6.0
OUTCOME MEASURES..............................................................................14
7.0
CRITERIA FOR REMOVAL FROM PROTOCOL AND
OFF-STUDY CRITERIA .............................................................................14
7.1
Off Study Criteria............................................................................................15
8.0
SAFETY AND ADVERSE EVENT REPORTING REQUIREMENTS..............18
9.0
DATA COLLECTION, STUDY MONITORING,
AND CONFIDENTIALITY..........................................................................15
10.0
STATISTICAL CONSIDERATIONS.............................................................16
11.0
OBTAINING INFORMED CONSENT ..........................................................18
12.0
STUDY DURATION ....................................................................................18
13.0
REFERENCES............................................................................................19

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
4
1.0 OBJECTIVES
1.1 Primary objective of this phase II study: To determine if hydroxyurea, dosed to
MTD, improves AdultQLTM 3.0 Sickle Cell Disease Module scores after 6 months of
hydroxyurea therapy at MTD compared to score at entry.
1.2 Secondary objectives of this study:
1.
Assess the role of phlebotomy for patients who fail to show a 10 point improvement
on the AdultQLTM 3.0 Sickle Cell Disease Module scores after 6 months at MTD of
hydroxyurea.
2.
To investigate the effect of hydroxyurea on HbSC rheology, including viscosity,
%dense red blood cells (%DRBC), red cell deformability, and time of transit through
an artificial microvascular network.
3.
To investigate changes in the following laboratory values of HbSC patients using
serial measurements every two months for the duration of the study:

Fetal hemoglobin (HbF) levels as determined by HPLC in the hemoglobin
profile

Mean corpuscular volume (MCV)

Mean corpuscular hemoglobin concentration (MCHC)

Hemoglobin (Hb) levels

Absolute reticulocyte count (ARC)

Absolute neutrophil count (ANC)

Complete metabolic panel (CMP)

Lactate dehydrogenase (LDH)

Unconjugated bilirubin (u.bili) levels

Microalbuminuria as measured by routine urinalysis (UA)
4.
(Optional) Genomic analysis of variants associated with HbF response and disease
related complications. Expression level changes from RNA obtained at baseline and
at stable MTD.
2.0 BACKGROUND AND RATIONALE
2.1
Hemoglobin SC disease
Patients with hemoglobin SC disease are compound heterozygotes. One beta globin gene
contains the sickle mutation, glutamic acid to valine change at the 6th codon, and the other beta
globin gene contains the C mutation, a change from glutamic acid to lysine, also at the 6th
codon. Each erythrocyte contains HbS and HbC in an approximate 50:50 ratio. Hemoglobin SC
disease is one of the most common inherited diseases in the United States, affecting
approximately 1 in 833 African-American live births.4 HbS undergoes intracellular
polymerization in the deoxygenated state, leading to deformation of the red cell membrane and
alteration of cellular physiology. While HbC does not polymerize, it increases the mean

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
5
corpuscular hemoglobin concentration (MCHC) of the cell via volume regulated K+ efflux,
thereby potentiating the polymerization of HbS.5 In vitro studies of HbSC red blood cells found
that reduction of MCHC from 37 to 33 g/dL would restore normal red blood cell morphology.6
Clinical manifestations of HbSS disease result primarily from chronic severe hemolytic anemia
and the effects of repeated intravascular sickling of erythrocytes within the capillaries and small
venules. Hemolysis leads to chronic anemia, gallstone formation, and intimal
damage/hyperplasia within the arterial vasculature. Red blood cell sickling leads to acute vaso-
occlusive events with varied presentations, including painful events, priapism, splenic
sequestration, acute chest syndrome, or stroke. These processes occur in HbSC disease as
well, but at 25-50% the frequency. Hemolysis in HbSC is reduced due to longer RBC survival,
approximately 25% of a normal individual, or 28.9 (+4) days, compared to less than 21 days in
HbSS disease.7
2.2
Role of whole blood viscosity in the pathophysiology of HbSC disease
Recent reports have shown higher whole blood viscosity to correlate with more frequent pain
events, leg ulcers, and ACS in patients with HbSS. Patients with HbSC disease have similar
rates of AVN, and higher rates of proliferative sickle retinopathy (PSR), than HbSS patients.1,8
Pain events and ACS, while less frequent than in HbSS, still commonly occur in HbSC,
especially in adolescence. These observations lead some providers to offer therapeutic
phlebotomy to symptomatic HbSC patients. A large series of 179 HbSC patients treated with
phlebotomy, reported 71% had significant reduction in pain events. The authors had
recommended phlebotomy for all symptomatic adult HbSC patients with Hb >10.5 g/dL. In this
phlebotomy therapy applied to adult HbSC patients, the Hb set point reduction is achieved by
inducing iron deficiency. Later publications noted the lack of linear relationship between
hemoglobin levels and whole blood viscosity. Current recommendations are to base phlebotomy
decisions on individual’s whole blood viscosity measurements.9
2.3
Hydroxyurea Therapy for HbSC disease: HbF response
Low levels of HbF in patients with SCD are associated with a variety of vaso-occlusive
complications and an increased risk for early death. In patients with HbSS, hydroxyurea
provides an important therapeutic option for patients with SCD, since it increases the amount of
HbF within circulating erythrocytes, can be administered orally with once-daily dosing, has
minimal short-term adverse effects, and is clinically effective. In a randomized, double-blinded,
placebo-controlled phase III trial involving severely affected adults with homozygous HbSS,
hydroxyurea therapy was associated with significantly fewer painful vaso-occlusive events,
episodes of acute chest syndrome, erythrocyte transfusions, and hospitalizations compared to
observation alone.10 The Multicenter Study of Hydroxyurea in Sickle Cell Anemia trial reported
that adult patients treated with hydroxyurea had a 40% reduction in overall mortality after 9
years of follow-up.11 In adults with SCD, hydroxyurea is well tolerated and leads to increases in
hemoglobin concentration, mean corpuscular volume (MCV), and percentage HbF, as well as
decreases in white blood cell and reticulocyte counts.12
Similar efficacy for hydroxyurea therapy has been observed in children with HbSS. A phase I/II
trial of hydroxyurea therapy in children 5 to 15 years of age with severe clinical manifestations

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
6
(HUG-KIDS) demonstrated similar safety and hematological toxicities and efficacy at MTD as
seen in adults.13 Hydroxyurea was well tolerated and had no negative effects on growth or
development.14 The most common short-term hydroxyurea toxicity was transient and reversible
myelosuppression, primarily of the granulocyte series. While there is compelling evidence for
the effectiveness of hydroxyurea in HbSS, HbSC patients were not included in these studies.
It has been hypothesized that HbSC patients may not benefit from hydroxyurea because adult
patients have baseline HbF<5%.15 In a cohort of 10 adult HbSC patients treated with
hydroxyurea at doses ranging 500-1000 mg per day, a significant increase in MCV was noted.
No significant change in HbF was noted for the group but one individual had a 6.8% rise in
HbF.16
A report by Dr. Ware of 6 pediatric patients with HbSC disease treated with hydroxyurea at MTD
between 1995 and 2002 in the Duke Pediatric Sickle Cell Program supports the clinical and
hematological efficacy of hydroxyurea therapy in children with HbSC disease. MCV increased
significantly without increase in hemoglobin. Additionally HbF percentage and percentage of F-
cells increased.3
Another study of eight pediatric HbSC patients placed on hydroxyurea therapy demonstrated an
increase in MCV, but only two patients had an increase in HbF. However, the hydroxyurea dose
was not increased to MTD, but remained stable at 15 mg/kg.17 Of note, review of the medical
charts of HbSC patients treated with hydroxyurea in our institution found the dose of
hydroxyurea needed to reach MTD ranged between 15-25mg/kg, average 20 mg/kg. This is
significantly lower than the average dose of 30 mg/kg needed to reach MTD in HbSS patients;18
therefore, it is likely that a HbSC patient will reach MTD more rapidly, typically after 1-2 dose
increases.
CHAMPS, a phase II double blinded multicenter trial examined the efficacy of hydroxyurea and
magnesium pidolate in children and adults with HbSC. In this trial, participants who received
hydroxyurea (± magnesium pidolate) had significant increases in MCV and HbF, without
changes in hemoglobin level. Unfortunately, clinical conclusions from this trial were limited
because of its incomplete enrollment and early termination. 19
2.4
Effect of Hydroxyurea on whole blood viscosity
Elevated hemoglobin has been implicated in several clinical complications of sickle cell disease.
The Cooperative Study of Sickle Cell Disease (CSSCD) identified increased hemoglobin as a
major risk factor for development of acute chest syndrome (ACS) in adults. Higher hemoglobin
values appear to correlate with increased frequency of pain crises.20,21 Since hemoglobin
concentration is the largest contributor to viscosity, it can be inferred that increased hemoglobin
concentration resulted in higher viscosity. A study of packed red blood cell rheology of HbSS
patients showed a strong correlation between increased viscosity and end organ damage.22
Patients with SCD are often transfused with non-sickled RBC in order to prevent or reverse
severe complications such as stroke or acute chest syndrome. These transfusions reduce blood
viscosity and increase oxygen transport effectiveness.23 However, if patients are transfused
above a hematocrit of 30%, hyperviscosity could worsen the condition the transfusion was
initiated to treat or prevent.24 This consideration must also guide any pharmacological therapy
that may increase hemoglobin, and therefore whole blood viscosity. It is of even higher

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
7
importance in patients with HbSC, who already have higher baseline hemoglobin values than
most HbSS individuals.
2.5
Hydroxyurea Response Variability in Sickle Cell Disease
The response to hydroxyurea therapy in SCD is highly variable.25 Patients are typically
escalated to the MTD based on laboratory myelosuppression, aiming for an absolute neutrophil
count of 1.0 – 3.0 x 109/L. With proper compliance, virtually every patient with SCD will
increase their HbF during hydroxyurea therapy at MTD, but the magnitude of the response
varies from 10% to >30% in HbSS. Currently, there is no way to predict which patient will have
a high or low HbF response to hydroxyurea prior to reaching MTD for HbSS patients, much
less the HbSC subtype. We hypothesize that genetic differences beyond the sickle gene
mutation influence the HbF response to hydroxyurea therapy, and that these differences may
be found in the various SCD subtypes as well as HbSS.
2.6
Treatment Rationale
Patients with HbSC generally have a milder course than HbSS patients. However, a select
number will have significant clinical complications in childhood, and a majority of patients with
HbSC develop chronic organ damage in adulthood. The potential efficacy of hydroxyurea to
postpone, prevent, or even reverse chronic organ damage in patients with HbSC disease has
not been determined for either children or adults. Viscosity is of major importance in the
pathophysiology of HbSC disease. A small trial of hydroxyurea in HbSC patients showed a
statistically significant rise in hemoglobin levels, which may increase whole blood viscosity.26 In
our study, patients who do not show clinical improvement on hydroxyurea will be placed on
therapeutic phlebotomy if their whole blood viscosity is at or above baseline at either shear
rate. Patients will not be taken off of hydroxyurea when phlebotomy is initiated. They will not be
on study therapy, but will continue to be monitored clinically, and rheological testing performed.
This allows collection of preliminary data to assess an alternative therapy widely used in adult
HbSC patients in Europe.27
2.7
AdultQLTM 3.0 Sickle Cell Disease Module
The AdultQLTM 3.0 Sickle Cell Disease Module is based on frequently used generic health
related quality of life tools (HRQL). It is a 43 item module. It contains questionnaires to be
administered to the patient and the parent if present. This clinical research tool has been
validated, found reliable and feasible in a multi-center trial. Texas Children’s Hematology Center
participated in this trial, where it was self-administered in the clinic setting where appropriate.
3.0
RESEARCH PARTICIPANT ELIGIBILITY CRITERIA AND STUDY
ENROLLMENT
3.1
Inclusion Criteria
3.1.1
Diagnosis of HbSC disease
3.1.2
Age from 18 to 69 years of age.
3.1.3
Score of 80 or lower on the AdultQLTM 3.0 Sickle Cell Disease Module,
or any disease related complication, including, but not limited to, one or
more pain events per year, proliferative sickle retinopathy, avascular

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
8
necrosis, cholelithiasis, or any thrombotic event. If the subject has a score
>80, they may still enroll on the trial, and be analyzed for secondary
endpoints. They will be excluded from analysis of the primary endpoint.
3.2
Exclusion Criteria
3.2.1
Failure to meet inclusion criteria
3.2.2
Hydroxyurea usage in the last 3 months.
3.2.3
Chronic RBC transfusion therapy
3.2.4
Packed red blood cell transfusion in the last 3 months (temporary
exclusion).
3.2.5
Pregnancy, or refusal to use medically effective birth control if female and
sexually active.
3.2.6
Current phlebotomy therapy
3.3
Research Participant Recruitment and Screening
Study participants will be patients with HbSC disease who receive medical care from the Texas
Children's Cancer and Hematology Centers (TCC/HC)/Baylor College of Medicine (BCM) and
the University of Texas Houston Hematology Center. Recruitment of external participants will
consist of those physicians and patients who contact the Texas Children’s Hospital principal
investigator and/or the University of Texas Houston Hematology Center principal investigator
and express an interest in participating. Physicians and patients may learn of this study either
through the www.clinicaltrials.gov website or via presentations at scientific meetings. Of
patients followed at the Texas Children's Cancer and Hematology Centers (TCC/HC)/Baylor
College of Medicine (BCM) and the University of Texas Houston Hematology Center, all
patients with HbSC disease will be screened with AdultQLTM 3.0 Sickle Cell Disease Module.
Those with a score of 80 or lower, or any disease related clinical complication, will be offered
hydroxyurea therapy and invited to participate in this study. The protocol will be explained to
them and consent obtained by the Principal Investigator or her designee.
3.4
Enrollment on Study
Subjects will be recruited from the patient population followed at the Texas Children's Cancer
and Hematology Centers (TCC/HC)/Baylor College of Medicine (BCM) and the University of
Texas Houston Hematology Center. Eligibility to the study will be confirmed by the Principal
Investigator or her designee based on the inclusion/exclusion criteria defined in Section 3.0 of
the protocol. All patients who meet eligibility criteria will be approached for consent at their
scheduled physician/clinic visit. The investigational nature and objectives of the study, the
procedures involved and their attendant risks and discomforts, and potential alternative options
will be carefully explained to the patients. If they would like to proceed, written consent will be
obtained from eligible subjects, in conformity to the BCM and UT human research policies and
to the federal regulations.
4.0
STUDY DESIGN AND METHODS
4.1
Study Design

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
9
The primary objective of this Phase II study is to prospectively and uniformly treat
symptomatic HbSC patients to MTD on hydroxyurea, and assess for clinical
improvement using the AdultQLTM 3.0 Sickle Cell Disease Module after 6 months
in the study, compared to entrance scores.
Also examined will be the effects of hydroxyurea on viscosity, red cell density,
Hb, HbF, MCV, MCHC, ANC and ARC. LDH and unconjugated bilirubin will be
monitored as indirect measures of hemolysis. Hydroxyurea dose escalation to a
stable MTD with evidence of mild myelosuppression will occur according to
published guidelines.28
Patients who do not show improvement after treatment with hydroxyurea for 6
months at MTD will offered phlebotomy, and observed clinically and rheologically
on study. Phlebotomy may be required monthly, but only visits two months apart
will include questionnaire administration. A sample for rheological measurements
will be obtained with each phlebotomy, but no less than every two months. Since
initially phlebotomy will be performed monthly, rheological analysis may occur
more often than every two months. Hydroxyurea will not be continued, and iron
deficiency will not be prevented. Standard phlebotomy guidelines will be
followed. Induction of iron deficiency has been shown to be beneficial in reducing
viscosity-related complications in sickle cell disease, and will reduce the
erythropoietic drive, prolonging the effects of phlebotomy.29-31
This is an unblinded Phase II trial; all patients enrolled will be placed on open-
label hydroxyurea. Drug effect will be determined based on change in laboratory
values from baseline. All laboratory tests, red cell density and viscosity measures
will be performed every two months. Testing will be performed on peripheral
blood obtained during hydroxyurea monitoring visits.
4.2
METHODS
4.2.1. Viscosity measurements
Measures of whole blood viscosity will be performed according to current guidelines.32
Whole blood will be obtained at routine clinic visits and collected in EDTA tubes, and
analyzed within 4 hours of venipuncture. All specimens will be warmed to 37oC prior to
measurement. A Brookfield cone and plate viscometer in Dr. Sheehan’s laboratory will
be used. Samples will be run at moderate and high shear stress, 45 s-1 and 225 s-1
respectively, at 37oC. 0.5 ml of whole blood will be used for each measure. The sample
used for viscosity measures will also be analyzed on the ADVIA 120 hematology
analyzer in order to measure the red cell density.
4.2.2
Laboratory measurements
Routine clinical laboratory assays will be performed at Texas Children’s Hospital clinical
laboratories and University of Texas Houston Hematology Center clinical laboratories.

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
10
Research lab assays will be performed in Dr Sheehan’s laboratory. ADVIA and
measurements will be used for research purposes only, to determine red cell density.
4.2.3. Studies of phenotypic variability
The HbF response will be evaluated as both a continuous and a categorical variable.
Change in HbF at MTD will be analyzed as a continuous variable using linear regression
analysis. Peripheral blood mononuclear cells will be isolated from 5mL venous blood,
and genomic DNA will be purified using standard laboratory techniques. Small aliquots
of DNA will then be tested for genetic variations that could modify the baseline and
treatment HbF levels. Analyses will be performed to identify gene polymorphisms
associated with HbF response and other laboratory and clinical variables.
5.0
CLINICAL AND LABORATORY EVALUATIONS
Table 1: Study Roadmap
Entry
At MTD
Every two
months
Exit
AdultQLTM 3.0 Sickle
Cell Disease Module
x
x
x
X-rays of bilateral2
shoulders and hips
x
x
Retinal exam1
x
x
Sensorineural
hearing test2
x
x
Genomic DNA
extraction from
peripheral blood
x
RNA from peripheral
blood
X
x
CBC with differential
ARC
Hemoglobin profile
CMP
LDH
x
x
x
Microalbumin3
x
x
Rheological
measurements4
x
x
x
Pregnancy testing 5
X
X
X
1. May be obtained up to 2 months after enrollment
2. Optional exam (voluntary assessment)
3. If abnormal at study entry, microalbumin will be checked at every study visit4.May be
performed with each phlebotomy, no less than every two months, but potentially monthly

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
11
5. Only for female subjects who are sexually active and do not report a highly
effective method for contraception
Hydroxyurea Dosing Parameters:
Initiation: Initiate hydroxyurea at 10 mg/kg daily, with the exact dose rounded up or down to the
nearest practical dose based on formulation. The actual starting dose should be within 2.5 mg/kg of the
calculated 10 mg/kg dose.
Dose escalation: Escalate HU dose by 5 mg/kg/day every 8 weeks up to a maximum dose of 35
mg/kg/day if blood counts meet escalation criteria (see table below).
Response to Toxicity: If one or more blood counts fall into the toxic range, stop hydroxyurea and
recheck blood counts weekly. Restart hydroxyurea at the same dose if the affected blood counts recover
within 1 week. Reduce hydroxyurea dose by 2.5 mg/kg if toxicity persists for more than 1 week or if
there is a previous history of toxicity at the current dose.
Table 2: Criteria for Hydroxyurea escalation and cessation
Definition of MTD:
Dose of hydroxyurea at which ANC is between 1000 and 3000/μl, OR ARC is between 70,000 and 
100,000/μl, or platelet count is between 70,000 and 100,000/μl on CBC.
Determination of MTD and Dose Adjustments:
Subjects will be followed for a minimum of eight weeks after initiation and each dose adjustment
to determine if they meet criteria for MTD at this dose. The definition of MTD for study
purposes will be the dose at which the subject maintains an ANC, ARC, or platelet count
in the target range (defined in Table II) over one CBC check performed at eight weeks
after the last dose adjustment.
If criteria for toxicity are met, treatment will be suspended for one week and will then be
resumed at the same dose after count recovery is documented. If toxicity persists past one
week or if it occurs more than once at the same dose, therapy will be suspended until count
recovery and will then be restarted at a dose 2.5 mg/kg less than the prior dose.
Laboratory value
Toxicity Criteria (Any)
Escalation Criteria
(All Must be Met)
ANC (per ul)
< 1000
> 3000
ARC(perul)
<70,000
> 100,000
Platelets(per µl)
< 70,000
> 100,000

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
12
Any deviations from this dose adjustment regimen, including suspension of therapy, dose
reduction, or dose escalation, that do not meet the criteria detailed above must be reviewed
with the study P.I. before being put into effect. Certain circumstances will be considered as
grounds for such deviations without being considered a violation of study procedures:
(1) In consultation with the study P.I., the subject's primary clinician may choose not
to escalate the hydroxyurea dose despite 8-10 weeks of therapy at the current dose and
CBC parameters meeting criteria for escalation if the trajectory of changes in the subject's
CBC parameters (a rapid rise in MCV; a rapid drop in ANC, ARC, or platelet count)
suggests that the subject would not tolerate further dose escalation. In this situation, the
primary clinician, after consultation with the study PI, may choose to observe the subject
at the current dose for an additional four weeks before escalating therapy.
(2) In consultation with the study P.I., the subject's primary clinician may choose not
to escalate the hydroxyurea dose despite 8-10 weeks of therapy at the current dose and
CBC parameters meeting criteria for escalation if there is evidence of non-adherence to
therapy over this period. In this circumstance, the primary clinician must discuss the
importance of adherence with the subject and re-evaluate the suitability of dose escalation
after an additional four weeks of therapy at the current dose.
(3) In the event of significant illnesses such as severe systemic infection, acute renal
insufficiency or hepatic dysfunction, acute gastroenteritis, or other significant illnesses, the
primary clinician may decide, in consultation with the study P.I., to suspend therapy or
delay a scheduled dose escalation until the acute illness has resolved.
The reasons for and duration of any deviations from the scheduled dose escalation protocol
should be clearly documented. In all cases, a lack of dose escalation over a 12-14 week
period should lead to a review of the subject's status and suitability for continued participation
in the study.
Indications for Initiation of Phlebotomy:
AdultQLTM 3.0 Sickle Cell Disease Module score after 6 months of hydroxyurea therapy at MTD
unchanged or reduced compared to baseline.
Phlebotomy Schedule: The first phlebotomy volume will be 7 ml/kg, but may be increased to 10
ml/kg to obtain the target Hb of 9-10 g/dL. Initially, phlebotomy is to be performed monthly. If Hb is

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
13
≤9.0 g/dL on a phlebotomy visit, phlebotomy will not be performed, and phlebotomy visits will be 
spaced 2 months (8 weeks) apart.
5.1
Special Instructions for Evaluations
Whole blood viscosity measures will be performed on blood collected in EDTA vacutainer tubes,
on a Brookfield cone and plate viscometer. Measures will be taken no more than 4 hours after
sample collection, at shear rates of 45 and 225 s-1. Red cell density will be obtained using an
ADVIA hematology analyzer. Red cell deformability will be measured with a RheoScan
ektacytometer. Microfluidics will be analyzed with an artificial microfluidics network, proprietary
design of Dr. Shevkoplyas.33-35 All necessary equipment is present in the PI, Dr. Sheehan’s
laboratory, located on the 10th floor of the Feigin Center, or in the Shevkoplyas laboratory in the
Biomedical Engineering department at University of Houston.
5.1.1
Laboratory Evaluations: All laboratory testing, except whole blood viscosity and red cell
density, are currently obtained as a part of routine clinical management every 2 months in
patients with SCD who are initiating hydroxyurea therapy.
Vital Signs, weights and measures will be recorded during the subject’s participation in the
study. Results of laboratory studies for all study participants will be collected in the study
database for future analysis.
The PI, Dr. Sheehan, will receive DNA samples and laboratory data from study participants with
HbSC disease enrolled on the IRB approved study at the University of Texas Houston
Hematology Center.
DNA samples will be coded by researchers at the University of Texas Houston Hematology
Center to preserve anonymity prior to distribution to BCM. The samples will be transferred,
evaluated and stored in Dr. Sheehan’s laboratory. Once the coded samples have been obtained
from the University of Texas Houston Hematology Center the BCM investigator will perform
experimental rheology lab tests of viscosity and percent dense cell measurements, and all the
data analysis. The Shevkoplyas lab will perform ektacytometry and artificial microvascular
network analyses.
5.2
Medical Record Review
Study personnel at Texas Children’s Hospital/Baylor College of Medicine and the University of
Texas Houston will review the subject’s medical record to abstract results of the above tests that
have been done as routine care prior to participating in this study. Results will be considered to
be baseline (pre-therapy) data for the purpose of this protocol if they were obtained within 12
months of hydroxyurea treatment initiation. Texas Children’s Hospital/Baylor College of
Medicine and University of Texas Houston Hematology Center healthcare providers and study
personnel will have access to subject’s past medical history.
Confidentiality Protocol Accession Numbers assigned in the Patient and Protocol Management
(PPM) will be used in place of an identifier such as a medical record number. No research

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
14
participant names will be recorded on documents used in data analysis, or used on any
documents submitted for publication of study results.
Clinical data will be transcribed from source documents directly into an electronic database.
This database will be password protected and accessible only to the Principal Investigator and
her designated staff.
Additionally, we would like to monitor significant clinical events on an ongoing basis. Key areas
to be collected include information such as: 1) pain episodes 2) acute chest syndrome 3) stroke
or transient ischemic attacks, 4) acute splenic sequestration, 5) death.
These clinical complications are part of the sickle cell disease process, and have not been
linked to hydroxyurea use. Development of these complications will not prompt removal from the
hydroxyurea arm of the study. Since there is a correlation between stroke and more severe
anemia in HbSS, development of a stroke or TIA will prompt removal from the study if the
patient is on the phlebotomy arm.
Specific diagnoses, rather than signs or symptoms will be recorded whenever possible.
5.3
Off-Study Evaluations
No off-study evaluations are planned.
6.0
OUTCOME MEASURES
6.1 AdultQLTM Sickle Cell Module scores
6.2 Whole blood viscosity
6.3 Red cell density
6.4 Red cell deformability
6.5 Transit time through and artificial microfluidics network
6.6 Expression level changes due to hydroxyurea therapy
6.7 Laboratory analysis
6.8 Observed disease related complications during study period, compared to same
duration of time immediately preceding study entry.
6.9 Variability in Hydroxyurea Response: The genetic basis for hematological variability
of HbF induction for patients receiving hydroxyurea therapy at maximum tolerated
dose (MTD) will be assessed, through collection of genomic DNA, which will be
submitted for whole exome sequencing under NHGRI U54HG003273. This
sequencing information may also be used to investigate associations between
variants and disease related complications.
7.0
CRITERIA FOR REMOVAL FROM PROTOCOL AND
OFF-STUDY CRITERIA
7.1
Off-Study Criteria
1)
Subject decides to no longer participate in the study

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
15
2)
Pregnancy
3)
Investigators may discontinue any subject at their discretion, if in their
professional opinion, the subject’s health, safety, and/or well-being is threatened
by continued participation in the study.
4)
Subject decides to stop hydroxyurea treatment permanently
5)
Lost to follow-up—a letter will be sent to the last known address of study
participants who are lost to follow up informing them that they are being taken
off-study.
6)
Death
8.0
SAFETY AND ADVERSE EVENT REPORTING REQUIREMENTS
Subjects on study will have scheduled clinic visits every two months, and laboratory evaluations
throughout the period of dose titration to MTD and clinical observation, totaling a minimum of 12
months. Patients requiring more than 6 months to reach MTD will have the duration of study
increased to permit 6 months observation at MTD. HbSC patients often reach MTD at significantly
lower doses of hydroxyurea that HbSS, hastening achievement of MTD, often at 15-20 mg/kg/day.
Placement on phlebotomy will extend the study by an additional 6 months to permit 6 months
observation on this therapy.
During study visits, patients will be closely monitored for any clinical or laboratory evidence of
toxicity associated with hydroxyurea or phlebotomy.
All toxicities and adverse events will be
scored utilizing criteria listed in the Common Terminology Criteria for Adverse Events (CTCAE)
version 4.0 and toxicities ≥ grade 3 will be included in the visit data collection. Further assessment, 
testing, and interventions for any adverse events, including hydroxyurea dose reduction or
interruption of therapy, will be performed according to section 5.0, Response to Toxicity. Subjects
with severe (grade 3 or worse) toxicities or adverse events will be reviewed in detail by the study
P.I. in conjunction with the Study Coordinator and primary clinician and will be considered for
termination from the study. The Principal Investigator will provide a Continuing Review Report to
the Baylor College of Medicine IRB at least annually. In addition, all serious adverse events and
UPIRSOs that meet reporting criteria as defined by the BCM IRB will be submitted to the BCM
IRB per their policy. Expected adverse events will not be reported. Adverse events related to loss
of confidentiality will be reported.
All safety data collected on study participants will be reviewed by the Texas Children’s Non-
Cancer Data Review Committee (TXCH DRC).
9.0
DATA COLLECTION, STUDY MONITORING, AND CONFIDENTIALITY
Data collection and data management for this investigation will be conducted through the BCM
Department of Pediatrics, Section of Hematology-Oncology. Co-investigators assigned to this

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
16
protocol will be responsible for assisting the PI in assuring protocol compliance as well as
reviewing, transcribing and tracking of all clinical and safety related data. All co-investigators
will receive Human Subjects Protection training with appropriate annual updates as required.
Each subject’s medical record will be reviewed and existing data will be collected that is relevant
to this study.
Clinical data will be transcribed from source documents directly into an electronic database.
This database will be password protected and accessible only to the Principal Investigator and
her designated staff.
Confidentiality
Protocol Accession Numbers assigned in the Patient and Protocol Management (PPM) will be
used in place of an identifier such as a medical record number. No research participant names
will be recorded on documents used in data analysis, or used on any documents submitted for
publication of study results.
9.1
Potential Risks
All patients in this study will be on hydroxyurea, which has repeatedly been shown to be safe
and cause minimal side effects in patients with sickle cell disease when appropriately
monitored. The most common side effects associated with hydroxyurea therapy are a drop in
infection fighting cells, or white blood cells, platelets, which help the blood clot, stomach
discomfort, skin discoloration or roughness, and mild hair loss. Most patients taking hydroxyurea
do not experience these symptoms when dosed appropriately.
Potential risks include the risks associated with phlebotomy, which will be minimized by the use
of careful sterile technique when drawing blood from peripheral veins or venous access lines
that are already in place. The blood volume (total 6 mL per sampling point) being procured for
this study is well within our local institutional guidelines for maximal volume allowed.
Subjects may risk loss of confidentiality pertaining to protected health information obtained
during the study. To minimize this risk, these data will be collected and stored using coded
identifiers, locked storage facilities and password-protected databases, each accessible only to
the investigators.
There exists a small potential for special risks to privacy relevant to the collection and storage of
specimens for DNA, and the planned posting of coded genomic sequences to dbGaP. As the
study of these specimens will be restricted solely to identify gene polymorphisms in low versus
high Hydroxyurea responders, and stored samples will be labeled only by coded identifiers,
these special risks will be minimized.
10.0
STATISTICAL CONSIDERATIONS
The primary outcome measure of interest is the change in AdultQLTM 3.0 Sickle Cell Disease
Module 3.0 Sickle Cell Disease Module score after 6 months of hydroxyurea therapy at MTD
compared with baseline. Previous research suggests that the standard deviation (SD) of scores

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
17
is expected to be about 20 points.36 Assuming SD=20 at each time point and a correlation
between repeated measures of 0.50, a sample size of 34 subjects would be required to detect a
10 point change in scores after 6-months of hydroxyurea therapy at MTD versus baseline with
80% power using a two-sided, paired t-test. Therefore, a total of 41 subjects will be recruited for
this study to allow for a 20% attrition rate. Baseline patient characteristics will be summarized by
means with standard deviations, medians with 25th and 75th percentiles or frequencies with
percentages as appropriate.
A two-sided, paired t-test will be used to test the primary null hypothesis that there is no change
in AdultQLTM 3.0 Sickle Cell Disease Module 3.0 Sickle Cell Disease Module score at 6-months
of hydroxyurea therapy at MTD versus baseline. Statistical significance will be assessed at the
0.05 level. This hypothesis will also be tested using a general linear mixed model. The mixed
model will use all available data, include a fixed effect for time (discrete) and will assume an
unstructured matrix of correlated error terms. Approximate normality will be qualitatively
assessed using quantile-quantile plots, and data transformations will be used if required. The
mixed model will also be used to explore associations between the primary outcome measure
and baseline characteristics, simultaneously adjusting for time. A similar mixed model will also
be used to simultaneously assess differences from baseline at all repeated, q2 months time
points up to 12 months post-study entry. P-values will be adjusted using Holm’s step-down
Bonferonni correction, and statistical significance will be assessed at the 0.05 corrected level.
Secondary outcome measures, including viscosity, %DRBC, red cell deformability, transit time
through an artificial microfluidics network, Hb, HbF, MCV, MCHC, ANC, ARC, LDH and
unconjugated bilirubin will be similarly assessed. The proportion of patients requiring
phlebotomy will be estimated with 95% exact, binomial confidence intervals. Summary statistics
for baseline characteristics will also be stratified by phlebotomy group. Univariable analysis will
compare baseline characteristics between groups using independent, two-sample t-tests,
Wilcoxon rank sum test, or Fisher’s exact test as appropriate. A multiple logistic regression
model will be used to estimate odds ratios with 95% confidence intervals comparing patients
requiring phlebotomy versus those who do not require the procedure.
Subjects who stop HU therapy for any reason (e.g., pregnancy, toxicity, SCD complications
requiring other intervention, non-adherence to medication dosing, patient or family’s request to
discontinue therapy) will be considered off-therapy. Subjects who miss two or more follow-up
evaluations will be sent a letter indicating that they are “off-study”.
Phlebotomy will be offered to patients who do not show improvement in QoL scores after 6
months of hydroxyurea therapy at MTD. All primary and secondary outcome measures will be
assessed as described above. It is not known how many patients will meet criteria for
phlebotomy. Patients who meet criteria for phlebotomy may refuse phlebotomy, and elect to exit
the study or remain in the study on hydroxyurea therapy. Statistical analysis and calculation of
power needed to see effect therefore cannot be calculated. Inclusion of phlebotomy will allow us
to obtain preliminary data needed to design a clinical trial to assess phlebotomy therapy in
HbSC individuals who do not experience clinical improvement on hydroxyurea.
Whole exome sequencing will be performed on genomic DNA. Samples will be included in a
larger study of genetic variants involving pediatric and adult SCD genomes associated with HbF

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
18
levels at baseline and HbF levels at hydroxyurea MTD already underway (H31356). Linear
regression analysis and T1 gene based testing will be performed for each variable, with
genotype and age as an independent variables. Whole genome analysis may be performed in
the future.
RNA will be obtained from CD71+ cells at baseline and at MTD. RNASeq will be performed
on study samples, as well as HbSS samples collected on protocol H35374. Fractional counts will
be quantile-normalized followed by t-test for change in expression between paired samples pre-
hydroxyurea and at MTD.
We will identify individual transcripts, splice isoforms, allele-specific effects and gene networks
that are altered by hydroxyurea, and the association between the degree or type of alteration and
HbF response to hydroxyurea. We will also compare expression levels at baseline between
individuals, to determine if expression levels differ between individuals with higher or lower
endogenous HbF levels.
11.0
OBTAINING INFORMED CONSENT
The process of obtaining informed consent will follow UT institutional guidelines. Informed
consent will be obtained by the attending physician or his/her designee. After the diagnosis of
HbSC is confirmed and the research participant is deemed eligible, consent will be obtained
from the patient . Informed consent will be obtained prior to administration of the AdultQLTM 3.0
Sickle Cell Disease Module questionnaire. If the subject has a score >80, they may still enroll on
the trial, and be analyzed for secondary endpoints. They will be excluded from analysis of the
primary endpoint.
12.0
STUDY DURATION
This protocol describes a planned 12 months of therapy. Patients requiring more than 6 months
to reach MTD will have the duration of study increased to permit 6 months observation at MTD.
Placement on phlebotomy will extend the study by an additional 6 months.
At the end of this period, study participants on hydroxyurea, on phlebotomy, or on no disease
specific therapy will be asked if they would like to participate in a 2 year observation period. In
this observation period, the laboratory tests and AdultQLTM 3.0 Sickle Cell Disease Module
scores that were obtained every two months during the planned12 months of the study will be
administered at each clinic visit, scheduled according to clinic guidelines and individual need.
13.0
REFERENCES

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
19
1.
Powars DR, Hiti A, Ramicone E, Johnson C, Chan L. Outcome in hemoglobin SC
disease: a four-decade observational study of clinical, hematologic, and genetic factors.
Am J Hematol 2002;70:206-15.
2.
Sofat R, Casas JP, Webster AR, et al. Complement factor H genetic variant and age-
related macular degeneration: effect size, modifiers and relationship to disease subtype.
International journal of epidemiology 2012;41:250-62.
3.
Miller MK, Zimmerman SA, Schultz WH, Ware RE. Hydroxyurea therapy for pediatric
patients with hemoglobin SC disease. J Pediatr Hematol Oncol 2001;23:306-8.
4.
Motulsky AG. Frequency of sickling disorders in U.S. blacks. N Engl J Med
1973;288:31-3.
5.
Fabry ME, Kaul DK, Raventos-Suarez C, Chang H, Nagel RL. SC erythrocytes have an
abnormally high intracellular hemoglobin concentration. Pathophysiological
consequences. J Clin Invest 1982;70:1315-9.
6.
Morse PD, 2nd, Warth JA. Direct measurement of the internal viscosity of sickle
erythrocytes as a function of cell density. Biochimica et biophysica acta 1990;1053:49-
55.
7.
Barbedo MM, McCurdy PR. Red cell life span in sickle cell trait. Acta haematologica
1974;51:339-43.
8.
Serjeant BE, Mason KP, Acheson RW, Maude GH, Stuart J, Serjeant GR. Blood
rheology and proliferative retinopathy in homozygous sickle cell disease. The British
journal of ophthalmology 1986;70:522-5.
9.
Lemonne N, Lamarre Y, Romana M, et al. Impaired blood rheology plays a role in the
chronic disorders associated with sickle cell-hemoglobin C disease. Haematologica
2014;99:74-5.
10.
Charache S, Terrin ML, Moore RD, et al. Effect of hydroxyurea on the frequency of
painful crises in sickle cell anemia. Investigators of the Multicenter Study of
Hydroxyurea in Sickle Cell Anemia. N Engl J Med 1995;332:1317-22.
11.
Steinberg MH, Barton F, Castro O, et al. Effect of hydroxyurea on mortality and
morbidity in adult sickle cell anemia: risks and benefits up to 9 years of treatment. JAMA
2003;289:1645-51.
12.
Charache S, Dover GJ, Moore RD, et al. Hydroxyurea: effects on hemoglobin F
production in patients with sickle cell anemia. Blood 1992;79:2555-65.
13.
Kinney TR, Helms RW, O'Branski EE, et al. Safety of hydroxyurea in children with
sickle cell anemia: results of the HUG-KIDS study, a phase I/II trial. Pediatric
Hydroxyurea Group. Blood 1999;94:1550-4.
14.
Wang WC, Wynn LW, Rogers ZR, Scott JP, Lane PA, Ware RE. A two-year pilot trial of
hydroxyurea in very young children with sickle-cell anemia. J Pediatr 2001;139:790-6.
15.
Schroeder WA, Powars DR, Kay LM, et al. Beta-cluster haplotypes, alpha-gene status,
and hematological data from SS, SC, and S-beta-thalassemia patients in southern
California. Hemoglobin 1989;13:325-53.
16.
Lee K, Prehu C, Merault G, et al. Genetic and hematological studies in a group of 114
adult patients with SC sickle cell disease. Am J Hematol 1998;59:15-21.

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
20
17.
Iyer R, Baliga R, Nagel RL, et al. Maximum urine concentrating ability in children with
Hb SC disease: effects of hydroxyurea. Am J Hematol 2000;64:47-52.
18.
Ware RE. How I use hydroxyurea to treat young patients with sickle cell anemia. Blood
2009;115:5300-11.
19.
Wang W, Brugnara C, Snyder C, et al. The effects of hydroxycarbamide and magnesium
on haemoglobin SC disease: results of the multi-centre CHAMPS trial. Br J
Haematol;152:771-6.
20.
Castro O, Brambilla DJ, Thorington B, et al. The acute chest syndrome in sickle cell
disease: incidence and risk factors. The Cooperative Study of Sickle Cell Disease. Blood
1994;84:643-9.
21.
Nebor D, Bowers A, Hardy-Dessources MD, et al. Frequency of pain crises in sickle cell
anemia and its relationship with the sympatho-vagal balance, blood viscosity and
inflammation. Haematologica;96:1589-94.
22.
Platt OS, Thorington BD, Brambilla DJ, et al. Pain in sickle cell disease. Rates and risk
factors. N Engl J Med 1991;325:11-6.
23.
Phillips G, Jr., Coffey B, Tran-Son-Tay R, Kinney TR, Orringer EP, Hochmuth RM.
Relationship of clinical severity to packed cell rheology in sickle cell anemia. Blood
1991;78:2735-9.
24.
Alexy T, Sangkatumvong S, Connes P, et al. Sickle cell disease: selected aspects of
pathophysiology. Clin Hemorheol Microcirc;44:155-66.
25.
Zimmerman SA, Schultz WH, Davis JS, et al. Sustained long-term hematologic efficacy
of hydroxyurea at maximum tolerated dose in children with sickle cell disease. Blood
2004;103:2039-45.
26.
Steinberg MH, Nagel RL, Brugnara C. Cellular effects of hydroxyurea in Hb SC disease.
Br J Haematol 1997;98:838-44.
27.
Lionnet F, Hammoudi N, Stojanovic KS, et al. Hemoglobin sickle cell disease
complications: a clinical study of 179 cases. Haematologica 2012;97:1136-41.
28.
Ware RE. How I use hydroxyurea to treat young patients with sickle cell anemia. Blood
2010;115:5300-11.
29.
Markham MJ, Lottenberg R, Zumberg M. Role of phlebotomy in the management of
hemoglobin SC disease: case report and review of the literature. Am J Hematol
2003;73:121-5.
30.
Castro O, Poillon WN, Finke H, Massac E. Improvement of sickle cell anemia by iron-
limited erythropoiesis. Am J Hematol 1994;47:74-81.
31.
Brugnara C, Mohandas N. Red cell indices in classification and treatment of anemias:
from M.M. Wintrobes's original 1934 classification to the third millennium. Current
opinion in hematology 2013;20:222-30.
32.
Baskurt OK, Boynard M, Cokelet GC, et al. New guidelines for hemorheological
laboratory techniques. Clin Hemorheol Microcirc 2009;42:75-97.
33.
Sosa JM, Nielsen ND, Vignes SM, Chen TG, Shevkoplyas SS. The relationship between
red blood cell deformability metrics and perfusion of an artificial microvascular network.
Clin Hemorheol Microcirc 2014;57:275-89.

IM-SCYTHE
Version 1.0 (06/23/2015)
Version 1.1 (07/23/2015)
Version 2.0 (08/31/2015)
Version 3.0 (10/05/2015)
Version 4.0 (12/29/2015)
Version 4.1 (02/14/2017)
21
34.
Reinhart WH, Piety NZ, Goede JS, Shevkoplyas SS. Effect of osmolality on erythrocyte
rheology and perfusion of an artificial microvascular network. Microvascular research
2015;98C:102-7.
35.
Burns JM, Yang X, Forouzan O, Sosa JM, Shevkoplyas SS. Artificial microvascular
network: a new tool for measuring rheologic properties of stored red blood cells.
Transfusion 2012;52:1010-23.
36.
Panepinto JA, Torres S, Bendo CB, et al. PedsQL sickle cell disease module: feasibility,
reliability, and validity. Pediatr Blood Cancer 2013;60:1338-44.