A Study of HQK-1001 in Patients With Sickle Cell Disease

Inclusion Criteria: * Established diagnosis of SCD * Males and females between 12 and 60 years of age, inclusive * At least 3 episodes of a SCD-related crisis or complication in the 3 years prior to screening OR 1 episode of acute chest syndrome in the 5 years prior to screening * If receiving hydroxyurea, must be receiving a stable dose for at least 6 months prior to screening * If hydroxyurea treatment has been discontinued, at least 3 months have elapsed since last dose * If transfusion in the 4 months prior to screening, then HbA level \< 20% at screening * Average of the initial two HbF levels ≥ 2.0 % within ≤ 7 days prior to the initial dose of HQK-1001. The two must be obtained ≥ 24 hours apart * Ability to swallow tablets * Able and willing to give informed consent and assent (if applicable) * If subject is a woman of child-bearing potential (WCBP), she must have a negative serum pregnancy test within 7 days of first dose of HQK-1001 * If a subject is a WCBP, she must agree to use an effective form of contraception within 7 days of the initial dose of HQK-1001 and for one month after HQK-1001 discontinuation * Sexually active male subjects (with WCBP partners) must agree to use latex condoms or ensure that their partner(s) use an effective form of contraception * In the view of the Investigator, subject is able and willing to comply with necessary study procedures Exclusion Criteria: * More than 4 hospitalizations for acute sickle cell related events in the previous 12 months prior to screening * Pulmonary hypertension requiring oxygen therapy * QTc \> 450 msec (male) or 470 msec (female) on screening ECG (QT corrected by Fridericia's formula) * Assigned to a regular transfusion program * Use of erythropoiesis stimulating agents within 90 days of screening * ALT \> 3x upper limit of normal (ULN) * Serum creatinine \> 1.2 mg/dL * A serious, concurrent illness that would limit ability to complete or comply with the study requirements * An acute vaso-occlusive event within 3 weeks prior to screening * Creatine phosphokinase (CK) \> 20% above the ULN * An acute illness (e.g., febrile, GI, respiratory) within 72 hours prior to screening * History of syncope, clinically significant dysrhythmias or resuscitation from sudden death * Chronic opiate use, which, in the view of the Investigator, could confound evaluation of an investigational drug * Current abuse of alcohol or drugs * Received another investigational agent within 4 weeks or 5 half-lives, whichever is longer, prior to screening * Currently pregnant or breast feeding a child * Known infection with HIV-1 * Infection with hepatitis B or hepatitis C, such that patients are currently on therapy or will be placed on therapy during the trial