What new drugs are approved for use in the treatment of sickle cell disease (SCD)?

Updated: May 12, 2021
  • Author: Joseph E Maakaron, MD; Chief Editor: Emmanuel C Besa, MD  more...
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In 2017, the US Food & Drug Administration (FDA) approved L-glutamine oral powder (Endari) for patients age 5 years and older to reduce severe complications of SCD. [58, 59]  L-glutamine increases the proportion of the reduced form of nicotinamide adenine dinucleotides in sickle cell erythrocytes; this probably reduces oxidative stress, which contributes to the pathophysiology of SCD. [60]

Approval of L-glutamine was based on data from a randomized, placebo-controlled trial in which, over the course of 48 weeks, patients receiving L-glutamine had fewer hospital visits for pain crises that resulted in treatment with parenteral narcotics or ketorolac (median three vs four), fewer hospitalizations for sickle cell pain (median two vs three), and fewer days in hospital (median 6.5 vs 11). In addition, fewer patients taking L-glutamine had episodes of acute chest syndrome (8.6% vs 23.1%). [58, 59]

Crizanlizumab, a P-selectin inhibitor, was approved by the FDA in 2019 to reduce the frequency of vaso-occlusive crisis (VOC) in adults with SCD. Binding P-selectin on the surface of activated endothelium and platelet cells blocks interactions between endothelial cells, platelets, red blood cells (RBCs), and leukocytes. Approval was based on the SUSTAIN clinical trial, in which crizanlizumab reduced the median annual rate of VOCs leading to health care visits by 45.3% compared with placebo (1.63 vs 2.98, P=0.010) in patients with or without hydroxyurea treatment. [61, 62]

Voxelotor was also approved by the FDA in 2019. It is indicated for treatment of SCD in adults and adolescents aged 12 years or older. Voxelotor is a hemoglobin S (HbS) polymerization inhibitor that binds to HbS with a 1:1 stoichiometry and exhibits preferential partitioning to RBCs. By increasing the affinity of Hb for oxygen, voxelotor demonstrates dose-dependent inhibition of HbS polymerization. Results showed 51% patients on the higher dose of voxelotor achieved a hemoglobin response compared with 6% with placebo. [63]

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