ABCC2 c.-24 C>T single-nucleotide polymorphism was associated with the pharmacokinetic variability of deferasirox in Chinese subjects

Genetic polymorphisms influencing deferasirox pharmacokinetics, efficacy, and adverse drug reactions: a systematic review and meta-analysis

Objective: Deferasirox is an iron-chelating agent prescribed to patients with iron overload. Due to the interindividual variability of deferasirox responses reported in various populations, this study aims to determine the genetic polymorphisms that influence drug responses. Methods: A systematic search was performed from inception to March 2022 on electronic databases. All studies investigating genetic associations of deferasirox in humans were included, and the outcomes of interest included pharmacokinetics, efficacy, and adverse drug reactions. Fixed- and random-effects model meta-analyses using the ratio of means (ROM) were performed. Results: Seven studies involving 367 participants were included in a meta-analysis. The results showed that subjects carrying the A allele (AG/AA) of ABCC2 rs2273697 had a 1.23-fold increase in deferasirox C_max (ROM = 1.23; 95% confidence interval [CI]:1.06-1.43; p = 0.007) and a lower Vd (ROM = 0.48; 95% CI: 0.36-0.63; p < 0.00001), compared to those with GG. A significant attenuated area under the curve of deferasirox was observed in the subjects with UGT1A3 rs3806596 AG/GG by 1.28-fold (ROM = 0.78; 95% CI: 0.60-0.99; p = 0.04). In addition, two SNPs of CYP24A1 were also associated with the decreased C_trough: rs2248359 CC (ROM = 0.50; 95% CI: 0.29-0.87; p = 0.01) and rs2585428 GG (ROM = 0.47; 95% CI: 0.35-0.63; p < 0.00001). Only rs2248359 CC was associated with decreased C_min (ROM = 0.26; 95% CI: 0.08-0.93; p = 0.04), while rs2585428 GG was associated with a shorter half-life (ROM = 0.44; 95% CI: 0.23-0.83; p = 0.01). Conclusion: This research summarizes the current evidence supporting the influence of variations in genes involved with drug transporters, drug-metabolizing enzymes, and vitamin D metabolism on deferasirox responses.

Clinical Challenges with Iron Chelation in Beta Thalassemia

Conventional therapy for severe thalassemia includes regular red cell transfusions and iron chelation therapy to prevent and treat complications of iron overload. Iron chelation is very effective when appropriately used, but inadequate iron chelation therapy continues to contribute to preventable morbidity and mortality in transfusion-dependent thalassemia. Factors that contribute to suboptimal iron chelation include poor adherence, variable pharmacokinetics, chelator adverse effects, and difficulties with precise monitoring of response. The regular assessment of adherence, adverse effects, and iron burden with appropriate treatment adjustments is necessary to optimize patient outcomes.

Fluorescence-based methods for studying activity and drug-drug interactions of hepatic solute carrier and ATP binding cassette proteins involved in ADME-Tox

In humans, approximately 70% of drugs are eliminated through the liver. This process is governed by the concerted action of membrane transporters and metabolic enzymes. Transporters mediating hepatocellular uptake of drugs belong to the SLC (Solute carrier) superfamily of transporters. Drug efflux either toward the portal vein or into the bile is mainly mediated by active transporters of the ABC (ATP Binding Cassette) family. Alteration in the function and/or expression of liver transporters due to mutations, disease conditions, or co-administration of drugs or food components can result in altered pharmacokinetics. On the other hand, drugs or food components interacting with liver transporters may also interfere with liver function (e.g., bile acid homeostasis) and may even cause liver toxicity. Accordingly, certain transporters of the liver should be investigated already at an early stage of drug development. Most frequently radioactive probes are applied in these drug-transporter interaction tests. However, fluorescent probes are cost-effective and sensitive alternatives to radioligands, and are gaining wider application in drug-transporter interaction tests. In our review, we summarize our current understanding about hepatocyte ABC and SLC transporters affected by drug interactions. We provide an update of the available fluorescent and fluorogenic/activable probes applicable in in vitro or in vivo testing of these ABC and SLC transporters, including near-infrared transporter probes especially suitable for in vivo imaging. Furthermore, our review gives a comprehensive overview of the available fluorescence-based methods, not directly relying on the transport of the probe, suitable for the investigation of hepatic ABC or SLC-type drug transporters.

Predicting disruptions to drug pharmacokinetics and the risk of adverse drug reactions in non-alcoholic steatohepatitis patients

The liver plays a central role in the pharmacokinetics of drugs through drug metabolizing enzymes and transporters. Non-alcoholic steatohepatitis (NASH) causes disease-specific alterations to the absorption, distribution, metabolism, and excretion (ADME) processes, including a decrease in protein expression of basolateral uptake transporters, an increase in efflux transporters, and modifications to enzyme activity. This can result in increased drug exposure and adverse drug reactions (ADRs). Our goal was to predict drugs that pose increased risks for ADRs in NASH patients. Bibliographic research identified 71 drugs with reported ADRs in patients with liver disease, mainly non-alcoholic fatty liver disease (NAFLD), 54 of which are known substrates of transporters and/or metabolizing enzymes. Since NASH is the progressive form of NAFLD but is most frequently undiagnosed, we identified other drugs at risk based on NASH-specific alterations to ADME processes. Here, we present another list of 71 drugs at risk of pharmacokinetic disruption in NASH, based on their transport and/or metabolism processes. It encompasses drugs from various pharmacological classes for which ADRs may occur when used in NASH patients, especially when eliminated through multiple pathways altered by the disease. Therefore, these results may inform clinicians regarding the selection of drugs for use in NASH patients.

Evaluation of Pharmacokinetics and Pharmacodynamics of Deferasirox in Pediatric Patients

Background: Deferasirox (DFX) is commonly used to reduce the chronic iron overload (IO) in pediatric patients. However, the drug is characterized by a large pharmacokinetic variability and approximately 10% of patients may discontinue the treatment due to toxicities. Therefore, the present retrospective study investigated possible correlations between DFX pharmacokinetics and drug-associated toxicities in 39 children (26 males), aged 2–17 years, who underwent an allogeneic hematopoietic stem cell transplantation. Methods: IO was diagnosed by an abdominal magnetic resonance imaging and DFX was started at a median dose of 500 mg/day. DFX plasma concentrations were measured by a high performance liquid chromatographic method with UV detection and they were analysed by nonlinear mixed-effects modeling. Results: The pharmacometric analysis demonstrated that DFX pharmacokinetics were significantly influenced by lean body mass (bioavailability and absorption constant), body weight (volume of distribution), alanine and aspartate transaminases, direct bilirubin, and serum creatinine (clearance). Predicted DFX minimum plasma concentrations (C_trough) accounted for 32.4 ± 23.2 mg/L (mean ± SD), and they were significantly correlated with hepatic/renal and hematological toxicities (p-value < 0.0001, T-test and Fisher’s exact tests) when C_trough threshold values of 7.0 and 11.5 mg/L were chosen, respectively. Conclusions: The population pharmacokinetic model described the interindividual variability and identified C_trough threshold values that were predictive of hepatic/renal and hematological toxicities associated with DFX.

Genetic factors involved in delayed methotrexate elimination in children with acute lymphoblastic leukemia

BACKGROUND

Delayed excretion of methotrexate can lead to life-threatening toxicity that may result in treatment cessation, irreversible organ damage, and death. Various factors have been demonstrated to influence the pharmacokinetic process of methotrexate, including genetic and nongenetic factors.

METHODS

We investigated the genetic factors primarily related to the metabolic pathway of methotrexate in children with acute lymphoblastic leukemia with delayed elimination, defined as C_44-48h ≥ 1.0μmol/L in this study. A total of 196 patients (delayed excretion group: 98; normal excretion group: 98) who received CCCG-ALL-2015 protocol after propensity score-matched analysis were included in the study. Twenty-eight target single-nucleotide polymorphisms (SNPs) were analyzed by multiplex polymerase chain reaction and sequencing, and 25 SNPs were finally included in the study.

RESULTS

The genotype distribution of SLCO1B1 rs2306283 SNP was different between the delayed and normal excretion groups. SLCO1B1 rs2306283 AA carriers had a significantly lower methotrexate C_44-48h /D ratio than GG carriers in both groups. Furthermore, compared with the normal excretion group, SLCO1B1 rs2306283 AG and GG were risk factors for developing oral mucositis (odds ratio [OR]: 2.13; 95% confidence interval [CI]: 1.11-4.08; P < .001), hepatotoxicity (OR: 2.12; 95% CI: 1.26-3.56; P < .001), and myelosuppression (OR: 1.21; 95% CI: 1.04-1.41; P = .005) in delayed excretion group.

CONCLUSIONS

The results from this study indicate the potential role of SLCO1B1 rs2306283 as a pharmacogenomic marker to guide and optimize methotrexate treatment for delayed elimination in children with acute lymphoblastic leukemia.

Effect of Genetic Polymorphisms on the Pharmacokinetics of Deferasirox in Healthy Chinese Subjects and an Artificial Neural Networks Model for Pharmacokinetic Prediction

BACKGROUND AND OBJECTIVE

Deferasirox is an oral iron chelator used to reduce iron levels in iron-overloaded patients with transfusion-dependent anemia or non-transfusion-dependent thalassemia. This study investigated the effects of genetic polymorphisms on the pharmacokinetics of deferasirox in healthy Chinese subjects and constructed a pharmacokinetic prediction model based on physiologic factors and genetic polymorphism data.

METHODS

Twenty-eight subjects were enrolled in a randomized, open-label, two-period crossover study, and they received a single dose of one of two formulations of deferasirox (20 mg/kg) with a 7-day washout interval between the two periods. The plasma defersirox concentration was determined using a validated liquid chromatography-tandem mass spectrometry method, and pharmacokinetic parameters were calculated using the noncompartmental method. The polymorphisms of uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1), UGT1A3, multidrug resistance protein 2 (MRP2), cytochrome P450 1A1 (CYP1A1), and breast cancer resistance protein 1 (BCRP1) were genotyped using Sanger sequencing. A back-propagation artificial neural network (BP-ANN) model was used to predict the pharmacokinetics.

RESULTS

The UGT1A1 rs887829 C > T single-nucleotide polymorphism (SNP) significantly influenced the area under the plasma concentration-time curve and the terminal half-life. Neither the MRP2 rs2273697 G > A SNP nor BCRP1 rs2231142 G > T SNP altered the absorption, disposition, and excretion of the drug. The BP-ANN model had a high goodness-of-fit index and good coherence between the predicted and measured concentrations (R² = 0.921).

CONCLUSION

Metabolic enzyme-related genetic polymorphisms were more strongly associated with the pharmacokinetics of deferasirox than membrane transporter-related genetic polymorphisms in the Chinese population.

TRIAL REGISTRATION

www.Chinadrugtrials.org.cn CTR20191164.