1.
Systematic review of voxelotor: a first-in-class sickle hemoglobin polymerization inhibitor for management of sickle cell disease
Han J, Saraf SL, Gordeuk VR
Pharmacotherapy. 2020
Abstract
Voxelotor, a sickle hemoglobin polymerization inhibitor, was approved by the U.S. Food and Drug Administration to treat sickle cell disease (SCD) in November 2019. This article reviews published data about voxelotor treatment of SCD based on a search of Medline, Embase, and International Pharmaceutical Abstracts. In a phase I/II trial, voxelotor demonstrated a dose-dependent pharmacokinetic and pharmacodynamic response and was well-tolerated in healthy volunteers and patients with SCD. In a multi-center, randomized, double-blind, phase III trial (HOPE trial), a significantly higher percentage of patients randomized to voxelotor had increased hemoglobin (> 1g/dL from baseline) compared to placebo. A greater reduction of hemolytic markers was also observed in the voxelotor-treated group, whereas the incidence of adverse effects was comparable. Three case series or reports also demonstrated the efficacy and safety of voxelotor use in a limited number of SCD patients in the real-world situation, although one patient with SCD, severe anemia, and a history of autoantibody-mediated hemolysis failed to respond to voxelotor. An ongoing trial (HOPE-KIDS) is designed to establish the use of voxelotor in younger pediatric patients with SCD. There is a theoretical concern that voxelotor may impair oxygen delivery, due to modification of the oxygen affinity of hemoglobin, which needs to be further evaluated. As a first-in-class hemoglobin modulator, voxelotor offers a new treatment option targeting the root cause of SCD.
2.
A Phase 3 Randomized Trial of Voxelotor in Sickle Cell Disease
Vichinsky E, Hoppe CC, Ataga KI, Ware RE, Nduba V, El-Beshlawy A, Hassab H, Achebe MM, Alkindi S, Brown RC, et al
The New England journal of medicine. 2019
Abstract
BACKGROUND Deoxygenated sickle hemoglobin (HbS) polymerization drives the pathophysiology of sickle cell disease. Therefore, direct inhibition of HbS polymerization has potential to favorably modify disease outcomes. Voxelotor is an HbS polymerization inhibitor. METHODS In a multicenter, phase 3, double-blind, randomized, placebo-controlled trial, we compared the efficacy and safety of two dose levels of voxelotor (1500 mg and 900 mg, administered orally once daily) with placebo in persons with sickle cell disease. The primary end point was the percentage of participants who had a hemoglobin response, which was defined as an increase of more than 1.0 g per deciliter from baseline at week 24 in the intention-to-treat analysis. RESULTS A total of 274 participants were randomly assigned in a 1:1:1 ratio to receive a once-daily oral dose of 1500 mg of voxelotor, 900 mg of voxelotor, or placebo. Most participants had sickle cell anemia (homozygous hemoglobin S or hemoglobin Sbeta(0)-thalassemia), and approximately two thirds were receiving hydroxyurea at baseline. In the intention-to-treat analysis, a significantly higher percentage of participants had a hemoglobin response in the 1500-mg voxelotor group (51%; 95% confidence interval [CI], 41 to 61) than in the placebo group (7%; 95% CI, 1 to 12). Anemia worsened between baseline and week 24 in fewer participants in each voxelotor dose group than in those receiving placebo. At week 24, the 1500-mg voxelotor group had significantly greater reductions from baseline in the indirect bilirubin level and percentage of reticulocytes than the placebo group. The percentage of participants with an adverse event that occurred or worsened during the treatment period was similar across the trial groups. Adverse events of at least grade 3 occurred in 26% of the participants in the 1500-mg voxelotor group, 23% in the 900-mg voxelotor group, and 26% in the placebo group. Most adverse events were not related to the trial drug or placebo, as determined by the investigators. CONCLUSIONS In this phase 3 randomized, placebo-controlled trial involving participants with sickle cell disease, voxelotor significantly increased hemoglobin levels and reduced markers of hemolysis. These findings are consistent with inhibition of HbS polymerization and indicate a disease-modifying potential. (Funded by Global Blood Therapeutics; HOPE ClinicalTrials.gov number, NCT03036813.).