Prevalence and cardiometabolic correlates of ketohexokinase gene variants among UK Biobank participants

LY3522348, A New Ketohexokinase Inhibitor: A First-in-Human Study in Healthy Adults

INTRODUCTION

This study aimed to assess the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of single and multiple doses of the ketohexokinase inhibitor LY3522348 in healthy participants.

METHODS

This first-in-human phase 1 study evaluated LY3522348, a highly selective, oral dual inhibitor of human ketohexokinase (KHK) isoforms C and A. The study was conducted in two parts: a single-ascending dose (SAD) study and a multiple-ascending dose (MAD) study, including a drug-drug interaction analysis with midazolam. Participants in the SAD study received single oral doses of LY3522348 ranging from 5 to 380 mg, while participants in the MAD study received once-daily doses of 50 mg, 120 mg, and 290 mg for 14 days.

RESULTS

A total of 65 healthy participants were included; of these 40 were in the SAD study (placebo = 10; LY3522348: 5 mg = 6; 15 mg = 6; 50 mg = 6; 150 mg = 6; 380 mg = 6) and 25 in the MAD study (placebo = 6; LY3522348: 50 mg = 6; 120 mg = 6; 290 mg = 7). LY3522348 was well tolerated, with the majority of the reported adverse events being mild. PK analysis showed an approximately dose-proportional increase in LY3522348 exposure, and the half-life ranged from 23.7 to 33.8 h. PD analysis indicated a dose-dependent increase in plasma fructose concentrations following the administration of a fructose beverage, supporting the inhibition of fructose metabolism by LY3522348.

CONCLUSIONS

LY3522348 demonstrated a favorable safety profile and well-behaved pharmacokinetics following once-daily oral dosing, and effective inhibition of fructose metabolism. The study was registered on ClinicalTrials.gov (NCT04559568).

Fructose restriction has beneficial effects on adipose tissue distribution but not on serum adipokine levels: Post-hoc analysis of a double-blind randomized controlled trial

We aimed to examine the effects of isocaloric fructose restriction on adipose tissue distribution and serum adipokines. Individuals with BMI >28 kg/m2 (n = 44) followed a 6-week fructose-restricted diet and were randomly allocated to (double-blind) oral supplementation with fructose (control) or glucose (intervention) powder three times daily. Visceral (VAT) and subcutaneous (SAT) adipose tissue was quantified with MRI. Serum interleukin 6 and 8, tumour necrosis factor alpha and adiponectin levels were measured with sandwich immunoassay. BMI decreased in both groups, but the change did not differ between groups (-0.1 kg/m2, 95%CI: -0.3; 0.5). SAT decreased statistically significantly in the control group (-23.2 cm3, 95%CI: -49.4; -4.1), but not in the intervention group. The change in SAT did not differ between groups (29.6 cm3, 95%CI: -1.2; 61.8). No significant differences in VAT were observed within or between study arms. The VAT/SAT ratio decreased statistically significantly in the intervention group (-0.02, 95%CI: -0.04; -0.003) and the change was significantly different between groups (-0.03, 95%CI: -0.54; -0.003). Serum adipokine levels were not affected by the intervention. This study shows that a fructose-restricted diet resulted in a favourable change in adipose tissue distribution, but did not affect serum adipokines. Further studies are warranted to clarify the underlying mechanisms how fructose affects adipose tissue distribution.

Gene variants of the SLC2A5 gene encoding GLUT5, the major fructose transporter, do not contribute to clinical presentation of acquired fructose malabsorption

Background

While role of ALDOB-related gene variants for hereditary fructose intolerance is well established, contribution of gene variants for acquired fructose malabsorption (e.g. SLC2A5, GLUT5) is not well understood.

Methods

Patients referred to fructose breath test were further selected to identify those having acquired fructose malabsorption. Molecular analysis of genomic DNA included (I) exclusion of 3 main ALDOB gene variants causing hereditary fructose intolerance and (II) sequencing analysis of SLC2A5 gene comprising complete coding region, at least 20 bp of adjacent intronic regions and 700 bp of proximal promoter.

Results

Among 494 patients, 35 individuals with acquired fructose malabsorption were identified based on pathological fructose-breath test and normal lactose-breath test. Thirty four of them (97%) had negative tissue anti-transglutaminase and/or deamidated gliadin antibodies in their medical records. Molecular analysis of SLC2A5 gene of all 35 subjects identified 5 frequent and 5 singular gene variants mostly in noncoding regions (promoter and intron). Allele frequencies of gene variants were similar to those reported in public databases strongly implying that none of them was associated with acquired fructose malabsorption.

Conclusions

Gene variants of coding exons, adjacent intronic regions and proximal promoter region of SLC2A5 gene are unlikely to contribute to genetic predisposition of acquired fructose malabsorption.

Molecular aspects of fructose metabolism and metabolic disease

Excessive sugar consumption is increasingly considered as a contributor to the emerging epidemics of obesity and the associated cardiometabolic disease. Sugar is added to the diet in the form of sucrose or high-fructose corn syrup, both of which comprise nearly equal amounts of glucose and fructose. The unique aspects of fructose metabolism and properties of fructose-derived metabolites allow for fructose to serve as a physiological signal of normal dietary sugar consumption. However, when fructose is consumed in excess, these unique properties may contribute to the pathogenesis of cardiometabolic disease. Here, we review the biochemistry, genetics, and physiology of fructose metabolism and consider mechanisms by which excessive fructose consumption may contribute to metabolic disease. Lastly, we consider new therapeutic options for the treatment of metabolic disease based upon this knowledge.