Study was stopped due to perceived futility because the baseline pain score in first 40 patients was too low to be able demonstrate an improvement

This study is designed to assess the safety, tolerability, and activity of TRF-1101 on microvascular blood flow, vascular endothelial injury, and vasoocclusive pain associated with sickle cell disease.

Inclusion Criteria:

• Be 18 years of age or older at the time of informed consent;
• Have a diagnosis of homozygous sickle cell anemia or sickle cell-beta° thalassemia;
• Have had 2 - 10 documented pain crises in the past year (pain crises are defined as visits to a medical clinic, Emergency Department or hospital, being bedridden and requiring constant analgesia at home for at least three days, or having a three-day interruption of life's activities [i.e., school, work, planned leisure activity] because of pain);
• If female and of child bearing potential, have a negative serum or urine pregnancy test and be using an effective birth-control method with a history of reliability for the individual patient (use of mifepristone is not allowed);
• Be properly informed of the nature and risks of the clinical investigation, be willing and able to comply with all clinical investigation-related procedures and assessments, and sign an Institutional Review Board (IRB) approved Informed Consent Form prior to entering the clinical investigation.

Exclusion Criteria:

• Have a history of abnormal bleeding, stroke, moya moya vascular malformations, or any other contraindication to anticoagulation;
• Be currently taking anticoagulant or thrombolytic medication;
• Be currently taking an endothelin receptor antagonist, e.g., bosentan (Tracleer®);
• Have a known sensitivity or allergy to heparin or related drugs;
• Have a history of thrombocytopenia (platelet count < 100 x 103/mm3) induced by heparin or related drugs;
• Have had fewer than 2 documented pain crises in the past year;
• Have had a pain crisis within one month of screening or randomization;
• If currently on or recently discontinued hydroxyurea treatment, have initiated or discontinued treatment or changed regimen within the past 6 months;
• Have had a transfusion within last 120 days or have HbA% > 15% from prior transfusion;
• Creatinine levels > 1.53 mg/dL (135 umol/L);
• ALT levels ≥ 3 times normal;
• Platelet count < 100 x 103/mm3;
• INR > 2.0;
• Be unable to tolerate oral medications;
• Have unreliable venous access;
• Be noncompliant with regular care;
• Have a positive pregnancy test, be currently lactating, or be trying to become pregnant;
• Have participation in an investigational drug or medical device study within previous 30 days;
• Have any other condition or circumstance that in the opinion of the Investigator makes the patient a poor candidate for participation in the study.