Advances in the Treatment of Sickle Cell Disease

Sickle cell disease (SCD) is a monogenic disorder that afflicts approximately 100,000 Americans and millions of people worldwide. It is characterized by hemolytic anemia, vaso-occlusive crises, relentless end-organ injury, and premature death. Currently, red blood cell transfusion and hydroxyurea are the major disease-modifying therapies available for SCD. Hematopoetic stem cell transplant is curative, but barriers to treatment are substantial and include a lack of suitable donors, immunologic transplant rejection, long-term adverse effects, prognostic uncertainty, and poor end-organ function, which is especially problematic for older patients. Gene therapy to correct the β^s point mutation is under investigation as another curative modality. Deeper insights into the pathophysiology of SCD have led to the development of novel agents that target cellular adhesion, inflammation, oxidant injury, platelets and/or coagulation, vascular tone, and hemoglobin polymerization. These agents are in preclinical and clinical trials. One such agent, L-glutamine, decreases red blood cell oxidant injury and is recently US Food and Drug Administration approved to prevent acute pain episodes of SCD in patients 5 years of age or older. The purpose of this review is to describe the currently established therapies, barriers to curative therapies, and novel therapeutic agents that can target sickle cell hemoglobin polymerization and/or its downstream sequelae. A PubMed search was conducted for articles published up to May 15, 2018, using the search terms sickle cell disease, novel treatments, hematopoietic stem cell transplantation, and gene therapy. Studies cited include case series, retrospective studies, prospective clinical trials, meta-analyses, online abstracts, and original reviews.