The influence of voxelotor on cerebral blood flow and oxygen extraction in pediatric sickle cell disease.

ABSTRACT: Voxelotor is an inhibitor of sickle hemoglobin polymerization that is used to treat sickle cell disease. Although voxelotor has been shown to improve anemia, the clinical benefit on the brain remains to be determined. This study quantified the cerebral hemodynamic effects of voxelotor in children with sickle cell anemia (SCA) using noninvasive diffuse optical spectroscopies. Specifically, frequency-domain near-infrared spectroscopy combined with diffuse correlation spectroscopy were used to noninvasively assess regional oxygen extraction fraction (OEF), cerebral blood volume, and an index of cerebral blood flow (CBFi). Estimates of CBFi were first validated against arterial spin-labeled magnetic resonance imaging (ASL-MRI) in 8 children with SCA aged 8 to 18 years. CBFi was significantly positively correlated with ASL-MRI-measured blood flow (R2 = 0.651; P = .015). Next, a single-center, open-label pilot study was completed in 8 children with SCA aged 4 to 17 years on voxelotor, monitored before treatment initiation and at 4, 8, and 12 weeks (NCT05018728). By 4 weeks, both OEF and CBFi significantly decreased, and these decreases persisted to 12 weeks (both P < .05). Decreases in CBFi were significantly correlated with increases in blood hemoglobin (Hb) concentration (P = .025), whereas the correlation between decreases in OEF and increases in Hb trended toward significance (P = .12). Given that previous work has shown that oxygen extraction and blood flow are elevated in pediatric SCA compared with controls, these results suggest that voxelotor may reduce cerebral hemodynamic impairments. This trial was registered at www.ClinicalTrials.gov as #NCT05018728.

Doping control approach: Identification of equine in vitro metabolites of voxelotor (GBT440), a hemoglobin S polymerization inhibitor.

RATIONALE: Sickle cell disease, a debilitating genetic disorder affecting numerous newborns globally, has historically received limited attention in pharmaceutical research. However, recent years have witnessed a notable shift, with the Food and Drug Administration approving three innovative disease-modifying medications. Voxelotor, also known as GBT440, is a promising compound that effectively prevents sickling, providing a safe approach to alleviate chronic hemolytic anemia in sickle cell disease. It is a novel, orally bioavailable small molecule that inhibits hemoglobin S polymerization by enhancing oxygen affinity to hemoglobin. The investigation demonstrated that voxelotor led to an unintended elevation of hemoglobin levels in healthy individuals by increasing serum erythropoietin levels. METHODS: Voxelotor and its metabolites in an in vitro setting utilizing equine liver microsomes were discussed. Plausible structures of the identified metabolites were inferred through the application of liquid chromatography in conjunction with high-resolution mass spectrometry. RESULTS: Under the experimental conditions, a total of 31 metabolites were detected, including 16 phase I metabolites, two phase II metabolites, and 13 conjugates of phase I metabolites. The principal phase I metabolites were generated through processes such as hydroxylation, reduction, and dissociation. The presence of glucuronide and sulfate conjugates of the parent drug were also observed, along with hydroxylated, reduced, and dissociated analogs. CONCLUSIONS: The data acquired will accelerate the identification of voxelotor and related compounds, aiding in the detection of their illicit use in competitive sports. It is crucial to emphasize that the metabolites detailed in this manuscript were identified through in vitro experiments and their detection in an in vivo study may not be guaranteed.

Quantitative Model-Based Assessment of Multiple Sickle Cell Disease Therapeutic Approaches Alone and in Combination.

Three sickle cell disease (SCD) treatment strategies, stabilizing oxygenated hemoglobin (oxyHb), lowering 2,3-BPG, and inducing fetal hemoglobin (HbF) expression aim to prevent red blood cell (RBC) sickling by reducing tense-state sickle hemoglobin that contributes to polymer formation. Induction of 30% HbF is seen as the gold standard because 30% endogenous expression is associated with a lack of symptoms. However, the level of intervention required to achieve equivalent polymerization protection by the other strategies is uncertain, and there is little understanding of how these approaches could work in combination. We sought to develop an oxygen saturation model that could assess polymerization protection of all three approaches alone or in combination by extending the Monod-Wymann-Changeux model to include additional mechanisms. Applying the model to monotherapies suggests 51% sickle hemoglobin (HbS) occupancy with an oxyHb stabilizer or lowering RBC 2,3 BPG concentrations to 1.8 mM would produce comparable polymerization protection as 30% HbF. The model predictions are consistent with observed clinical response to the oxyHb stabilizer voxelotor and the 2,3-BPG reducer etavopivat. The model also suggests combination therapy will have added benefit in the case of dose limitations, as is the case for voxelotor, which the model predicts could be combined with 20% HbF or 2,3-BPG reduction to 3.75 mM to reach equivalent protection as 30% HbF. The proposed model represents a unified framework that is useful in supporting decisions in preclinical and early clinical development and capable of evolving with clinical experience to gain new and increasingly confident insights into treatment strategies for SCD.

A potential therapeutic agent for the treatment of hyperuricemia and gout: 3,4-Dihydroxy-5-nitrobenzaldehyde phenylthiosemicarbazide.

Uric acid, the metabolic product of purines, relies on xanthine oxidase (XOD) for production. XOD is a target for the development of drugs for hyperuricemia (HUA) and gout. Currently, treatment options remain limited for gout patients. 3, 4-Dihydroxy-5-nitrobenzaldehyde (DHNB) is a derivative of the natural product protocatechualdehyde with good biological activity. In this work, we identify a DHNB thiosemicarbazide class of compounds that targets XOD. 3,4-Dihydroxy-5-nitrobenzaldehyde phenylthiosemicarbazone can effectively inhibit XOD activity (IC50 value: 0.0437 µM) and exhibits a mixed inhibitory effect. In a mouse model of acute hyperuricemia, a moderate dose (10 mg/kg.w) of 3,4-dihydroxy-5-nitrobenzaldehyde phenylthiosemicarbazide effectively controlled the serum uric acid content and significantly inhibited serum XOD activity. In addition, 3,4-Dihydroxy-5-nitrobenzaldehyde phenylthiosemicarbazide showed favorable safety profiles, and mice treated with the target compound did not show any symptoms of general toxicity following a single dose of 500 mg/kg. In the allopurinol group, 50 % of the mice died. These results provide a structural framework and mechanism of XOD inhibition that may facilitate the design of hyperuricemia and gout treatments.

Evaluation of the effect of voxelotor and darbepoetin alfa on hemoglobin levels in patients with sickle cell disease.

BACKGROUND: To date, there is limited evidence on patients utilizing both voxelotor and darbepoetin alfa and its impact on hemoglobin levels. The objective is to evaluate the effect of voxelotor and darbepoetin alfa on hemoglobin levels in patients with SCD. RESEARCH DESIGN AND METHODS: This was a retrospective chart review study that assessed the primary independent variable as the utilization of either voxelotor alone, darbepoetin alfa alone, or the concurrent administration of voxelotor and darbepoetin alfa. Descriptive statistics were utilized to obtain the mean standard deviation for numerical variables and proportions for categorical variables. RESULTS: A total of 23 participants were included in this study. When comparing baseline to 2 months and 3 months, participants on voxelotor alone experienced a 3% decrease and a 6.6% increase in hemoglobin, darbepoetin alfa alone group a 4.3% decrease and a 0.6% increase in hemoglobin and voxelotor and darbepoetin group a 4.4% decrease and a 0.5% decrease in hemoglobin levels. Fifty percent of the participants in the voxelotor group and 6 (66.7%) participants in the voxelotor plus darbepoetin alfa group experienced adverse drug events. CONCLUSIONS: Voxelotor resulted in a clinically significant difference in the percent change of hemoglobin from baseline to 3 months.

Predictive and therapeutic value of lipoprotein-associated phospholipaseA2 in sarcopenia in chronic obstructive pulmonary disease.

BACKGROUND: Sarcopenia, characterized by progressive muscle dysfunction, is a common complication of chronic obstructive pulmonary disease (COPD). Our previous study revealed serum Lipoprotein-associated phospholipaseA2 (Lp-PLA2) level significantly increased in COPD and associated with exercise tolerance. This study further investigated the functions and target potential of Lp-PLA2 for sarcopenia in COPD. METHODS: The circulating Lp-PLA2 level/enzyme activity in COPD patients and age-matched healthy volunteers were measured. Clinical parameters on skeletal muscle were measured and their correlations with Lp-PLA2 were analyzed. We explored the involvement of Lp-PLA2 in vivo and treatment effectiveness of darapladib (a specific Lp-PLA2 inhibitor) in CS-induced muscle dysfunction models. RESULTS: Circulating Lp-PLA2 level/enzyme activity was elevated in COPD patients compared with healthy controls, negatively associated with skeletal muscle mass and function. In CS-induced muscle dysfunction murine models, up-regulated serum Lp-PLA2 level/enzyme activity was verified again. In CS-exposed mouse models, darapladib treatment reversed muscle mass loss and muscle dysfunction, meanwhile rescued upregulation of MuRF1 and atrogin-1, and activation of inflammatory factors, oxidant enzymes and NF-κB signaling. CONCLUSIONS: Lp-PLA2 could be a potential indicator for sarcopenia in COPD. Darapladib, a Lp-PLA2 inhibitor, can alleviate CS-induced skeletal muscle dysfunction and represents a potential therapeutic for sarcopenia in COPD.

Randomized placebo controlled trial of phytoterpenes in DMSO for the treatment of plantar fasciitis.

Plantar fasciitis is the most common cause of heel pain in adults with an overall prevalence of 0.85% in the adult population of the US, affecting over 2 million adults annually. Most current treatment modalities are not supported by sufficient evidence to recommend one particular strategy over another. Topical application of analgesics for soft tissue pain is well established, however the plantar fascia presents challenges in this regard due to thick skin, fibrotic tissue, and an often thickened fat pad. Sixty-two patients with plantar fasciitis were randomized to a placebo controlled trial testing the efficacy of a topical solution of plant terpenes containing camphor, menthol, eugenol, eucalyptol, and vanillin. Skin permeation of the mixture was enhanced with 15% dimethylsulfoxide (DMSO), 1% limonene, and rosemary oil. One ml of solution was applied topically twice daily, and pain scores evaluated on Day 0, Day 1, Day 3, and Day 10. Using the validated foot function index 78.1% of patients reported an 85% or greater decrease in their total pain score by day 10 while placebo treatment was without effect (One Way ANOVA, P < 0.01). This study adapts the treatment modality of topical analgesia for soft tissue pain to a problematic area of the body and shows therapeutic promise.ClinicalTrials.gov Identifier: NCT05467631.