Diagnosis of sickle cell disease 
Clinically significant disease defined as at least 1 painful episode per year averaged over the previous 3 years or a history of priapism, stroke, acute chest syndrome, avascular necrosis, multi-organ failure or the need for chronic narcotic medications for pain from sickle cell disease 
Must have failed a previous attempt at treatment with hydroxyurea defined as the inability to achieve a significant absolute increase in % fetal hemoglobin or the inability to tolerate hydroxyurea treatment due to severe side effects such as but not limited to myelosuppression, gastrointestinal symptoms, edema or hepatic enzyme elevations or have contraindications to hydroxyurea 
18 years of age or older 
Hematologic laboratory values as outlined in the protocol 
Non-hematologic laboratory values as outlined in the protocol 
Must agree not to donate blood or other bodily fluid while taking the study drug and for 28 days thereafter 
Women of child-bearing potential (WCBP) must have a negative serum pregnancy test 72 hours or less prior to starting treatment 
Women of child-bearing potential and men must agree to use 2 forms of adequate contraception prior to study entry and for the duration of study participation 

NCT01000155_inc_T1
Condition
sickle cell disease
NCT01000155_inc_T2
Mood
Diagnosis
NCT01000155_inc_T3
Qualifier
Clinically significant
NCT01000155_inc_T4
Condition
Clinically significant disease
NCT01000155_inc_T5
Multiplier
per year averaged over the previous 3 years at least 1
NCT01000155_inc_T6
Condition
painful episode
NCT01000155_inc_T7
Temporal
the previous 3 years
NCT01000155_inc_T8
Qualifier
averaged over the previous 3 years
NCT01000155_inc_T9
Observation
history
NCT01000155_inc_T10
Condition
priapism
NCT01000155_inc_T11
Condition
stroke
NCT01000155_inc_T12
Condition
acute chest syndrome
NCT01000155_inc_T13
Condition
avascular necrosis
NCT01000155_inc_T14
Condition
multi-organ failure
NCT01000155_inc_T15
Mood
need for
NCT01000155_inc_T16
Multiplier
chronic
NCT01000155_inc_T17
Qualifier
chronic
NCT01000155_inc_T18
Drug
narcotic medications
NCT01000155_inc_T19
Condition
pain
NCT01000155_inc_T20
Condition
sickle cell disease
NCT01000155_inc_T21
Scope
at least 1 painful episode per year averaged over the previous 3 years or a history of priapism, stroke, acute chest syndrome, avascular necrosis, multi-organ failure or the need for chronic narcotic medications for pain from sickle cell disease
NCT01000155_inc_T23
Value
18 years or older
NCT01000155_inc_T24
Person
age
NCT01000155_inc_T29
Procedure
donate blood
NCT01000155_inc_T30
Negation
not
NCT01000155_inc_T31
Mood
Must agree to
NCT01000155_inc_T32
Procedure
donate bodily fluid
NCT01000155_inc_T33
Temporal
while taking the study drug
NCT01000155_inc_T34
Reference_point
taking the study drug
NCT01000155_inc_T35
Drug
study drug
NCT01000155_inc_T36
Temporal
for 28 days thereafter
NCT01000155_inc_T37
Scope
while taking the study drug and for 28 days thereafter
NCT01000155_inc_T38
Scope
donate blood or other bodily fluid
NCT01000155_inc_T39
Condition
child-bearing potential
NCT01000155_inc_T40
Person
Women
NCT01000155_inc_T41
Scope
Women of child-bearing potential
NCT01000155_inc_T42
Person
WCBP
NCT01000155_inc_T43
Measurement
serum pregnancy test
NCT01000155_inc_T44
Value
negative
NCT01000155_inc_T45
Temporal
72 hours or less prior to starting treatment
NCT01000155_inc_T46
Reference_point
starting treatment
NCT01000155_inc_T47
Procedure
treatment
NCT01000155_inc_T48
Scope
Women of child-bearing potential (WCBP)
NCT01000155_inc_T50
Condition
child-bearing potential
NCT01000155_inc_T51
Person
Women
NCT01000155_inc_T52
Person
men
NCT01000155_inc_T53
Mood
must agree to
NCT01000155_inc_T54
Multiplier
2 forms
NCT01000155_inc_T55
Procedure
contraception
NCT01000155_inc_T56
Qualifier
adequate
NCT01000155_inc_T57
Scope
Women of child-bearing potential and men
NCT01000155_inc_T58
Temporal
prior to study entry
NCT01000155_inc_T59
Temporal
for the duration of study participation
NCT01000155_inc_T60
Reference_point
study participation
NCT01000155_inc_T61
Reference_point
study entry