Addition of multimodal therapy to standard management of steady state sickle cell disease

Pilot assessment of omega-3 fatty acids and potassium thiocyanate in sickle cell anemia patients with conditional peak systolic cerebral artery blood velocity

OBJECTIVE

The purpose of this pilot study was to explore the effect of omega-3 fatty acids and potassium thiocyanate on conditional peak systolic cerebral artery blood velocity in children with sickle cell anemia (SCA).

METHODS

Transcranial doppler ultrasonography (TCD) was done on 232 SCA children, and 21 found with conditional peak systolic blood velocity (PSV) of 200-249 cm/s in internal carotid, middle or anterior cerebral arteries. These were randomized to receive omega-3 fatty acids and potassium thiocyanate with standard treatment of SCA (test group, N = 14), or standard treatment only (control group, N = 7). After 3 months of treatment, PSV was measured again.

RESULTS

Right middle cerebral artery PSV was significantly reduced in the test relative to the control groups (p = 0.04). PSV returned to normal in 79% of the test versus 43% of the control group; and increased to abnormal in one member of the control group, but none of the test group.

CONCLUSIONS

The pilot data suggest that in SCA, omega-3 fatty acids and potassium thiocyanate might reduce conditional blood velocity to normal, or prevent progression to abnormal values. A larger, randomized, clinical trial is required to further address the current gap in management of conditional TCD blood velocity.

Double-blind, randomized, multicenter phase 2 study of SC411 in children with sickle cell disease (SCOT trial)

Blood cell membranes in sickle cell disease (SCD) have low docosahexaenoic acid (DHA). DHA treatment reduces sickle cell crisis (SCC) rate and ameliorates the inflammation, oxidative stress, and hypercoagulable state of SCD. SC411 is a novel DHA ethyl ester formulation with a proprietary delivery platform (Advanced Lipid Technology) that enhances DHA bioavailability. The SCOT trial investigated the effect of 3 different doses of SC411 on clinical and biochemical endpoints in 67 children with SCD (5-17 years old). Seventy-six percent of subjects were also receiving hydroxyurea. After 4 weeks of treatment with SC411 at 20, 36, and 60 mg DHA/kg per day or placebo a statistically significant (P < .001) mean percentage increase of blood cell membrane DHA and eicosapentaenoic acid was seen vs baseline: 109.0% (confidence interval [CI], 46.7-171.3), 163.8% (CI, 108.3-219.2), 170.8% (CI, 90.2-251.4), and 28.6% (CI, 250.1 to 107.3), respectively. After 8 weeks of treatment, statistically significant changes vs placebo were also observed in D-dimer (P = .025) and soluble E-selectin (P = .0219) in subjects exposed to 36 mg/kg. A significant increase in hemoglobin was observed against placebo in subjects receiving 20 mg DHA/kg per day (P = .039). SC411 significantly reduced electronic diary recorded SCC, analgesic use at home, and days absent from school because of sickle cell pain. The lower rate of clinical SCC observed in the pooled active groups vs placebo did not reach statistical significance (rate ratio, 0.47; 95% CI, 0.20-1.11; P = .07). All tested doses were safe and well tolerated. This trial was registered at www.clinicaltrials.gov as #NCT02973360.

Investigational selectin-targeted therapy of sickle cell disease

INTRODUCTION

Under conditions of blood flow, selectins mediate the intercellular adhesion between erythrocytes, leukocytes, platelets and vascular endothelium that contribute to vaso-occlusion and tissue damage in sickle cell disease (SCD). Therefore, selectin antagonists have the potential to ameliorate SCD.

AREAS COVERED

In this review, the author discusses the cellular and molecular basis of vaso-occlusion in SCD, and presents evidence that selectin-mediated cell adhesion has clinical importance in this disorder. The author discusses molecular structure of human selectins and their physiological ligands and highlights clinical trials of selectin-targeted therapy of SCD. Herein, the author also assesses the benefits and limitations of the selectin antagonists that are currently under evaluation for SCD, and offers suggestions for the future.

EXPERT OPINION

In Phase I and II clinical trials, rivipansel and heparin demonstrated promising efficacy and safety in SCD. Although selectin blockade could potentially impair immune response, an increased incidence of infection was not reported in SCD patients treated with heparin (n = 127) or rivipansel (n = 111). The efficacy and safety findings from Phase I and II clinical studies are encouraging the commencement of Phase III studies to further evaluate selectin-targeted therapy in SCD.