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Background and Objectives: Hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infections present significant public health challenges worldwide. The management of these infections is complicated by the need for antiviral and antiretroviral therapies, which are influenced by drug metabolism mediated by metabolic enzymes and transporters. This study focuses on the gene expression of CYP2B6, CYP3A4, and ABCB1 transporters in patients with HIV, HCV, and HIV/HCV co-infection, aiming to assess their potential association with the choice of therapy, patohistological and clinical parameters of liver damage such as the stage of liver fibrosis, serum levels of ALT and AST, as well as the grade of liver inflammation and other available biochemical parameters. Materials and Methods: The study included 54 patients who underwent liver biopsy, divided into HIV-infected, HCV-infected, and co-infected groups. The mRNA levels of CYP2B6, CYP3A4, and ABCB1 was quantified and compared between the groups, along with the analysis of liver fibrosis and inflammation levels. Results: The results indicated a significant increase in CYP2B6 mRNA levels in co-infected patients, a significant association with the presence of HIV infection with an increase in CYP3A4 mRNA levels. A trend towards downregulation of ABCB1 expression was observed in patients using lamivudine. Conclusions: This study provides insight into gene expression of CYP2B6 CYP3A4, and ABCB1 in HIV, HCV, and HIV/HCV co-infected patients. The absence of correlation with liver damage, inflammation, and specific treatment interventions emphasises the need for additional research to elucidate the complex interplay between gene expression, viral co-infection, liver pathology, and therapeutic responses in these particular patients population.

Nowadays, direct oral anticoagulants (DOACs) are the first-line anticoagulant strategy in patients with non-valvular atrial fibrillation (NVAF). We aimed to identify the influence of polymorphisms of the genes encoding P-glycoprotein (ABCB1) and carboxylesterase 1 (CES1) on the variability of plasma concentrations of DOACs in Kazakhstani patients with NVAF. We analyzed polymorphisms rs4148738, rs1045642, rs2032582 and rs1128503 in ABCB1 and rs8192935, rs2244613 and rs71647871 CES1 genes and measured the plasma concentrations of dabigatran/apixaban and biochemical parameters in 150 Kazakhstani NVAF patients. Polymorphism rs8192935 in the CES1 gene (p = 0.04), BMI (p = 0.01) and APTT level (p = 0.01) were statistically significant independent factors of trough plasma concentration of dabigatran. In contrast, polymorphisms rs4148738, rs1045642, rs2032582 and rs1128503 in ABCB1 and rs8192935, rs2244613 and rs71647871 CES1 genes did not show significant influence on plasma concentrations of dabigatran/apixaban drugs (p > 0.05). Patients with GG genotype (138.8 ± 100.1 ng/mL) had higher peak plasma concentration of dabigatran than with AA genotype (100.9 ± 59.6 ng/mL) and AG genotype (98.7 ± 72.3 ng/mL) (Kruskal–Wallis test, p = 0.25). Thus, CES1 rs8192935 is significantly associated with plasma concentrations of dabigatran in Kazakhstani NVAF patients (p < 0.05). The level of the plasma concentration shows that biotransformation of the dabigatran processed faster in individual carriers of GG genotype rs8192935 in the CES1 gene than with AA genotype.

Inhibitori 3-hidroksi-3-metil-glutaril-koenzim-A (HMG-CoA) reduktaze (statini) najpropisivaniji su lijekovi u liječenju hiperkolesterolemije. U velikom broju kliničkih ispitivanja dokazana je njihova učinkovitost u smanjivanju rizika nastanka kardiovaskularnog događaja. Međutim, statini mogu imati i ozbiljne nuspojave kao što su miopatija i rabdomioliza. Novi identificirani rizični faktori za nastanak toksičnosti statina su genetičke varijante metaboličkih enzima i prijenosnika. Glavni cilj rada bio je odrediti učinak genskih varijanti CYP2C9, ABCB1, ABCC2, ABCG2 i SLCO1B1 na nastanak nuspojava povezanih s primijenjenom dozom simvastatina, atorvastatina i fluvastatina. U studiju je bilo uključeno 162 bolesnika koji su iskusili nuspojave povezane s dozom atorvastatina, fluvastatina i simvastatina te 162 bolesnika koji su uzimali ispitivane statine i nisu iskusili nuspojave (kontrolna skupina). Kontrolna skupina ispitanika je prema godinama, spolu, dozi i primjeni ciklosporina odgovarala bolesnicima koji su razvili nuspojavu. Rezultati studije pokazuju kako su varijante gena ABCG2 421C>A i CYP2C9*3 povezane s nastankom nuspojava fluvastatina, a varijante gena ABCG2 421C>A i SLCO1B1 521 C>A s nuspojavama atorvastina i simvastatina. Naša studija je prva povezala varijante gena ABCG2 s nastankom nuspojava statina. Naša je studija također prva ispitala i pokazala važnost farmakogenetičke predispozicije za nastanak nuspojava fluvastatina., 3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) are widely used for the treatment of hypercholesterolemia. Their efficacy in preventing cardiovascular events has been shown by a large number of clinical trials. However, adverse drug reactions (ADRs), sometimes serious, including myopathy or rhabdomyolysis, are associated with the use of statins. Newly identified risk factors for statin induced toxicity are genetic variants of drug metabolizing enzymes and membrane transporters. The aim of our study was to show influence of ABCB1, ABCC2, ABCG2, SLCO1B1 and CYP2C9 gene variants on development of atorvastatin, simvastatin and fluvastatin induced, dose related ADRs. One hundred sixty two patients that experienced statin induced ADRs and 162 controls matched for age, gender, dose and cyclosporine use were enrolled in the study. We found that ABCG2 421C>A and CYP2C9*3 variants were associated with fluvastatin induced ADRs, ABCG2 421C>A and SLCO1B1 521 C>A variants were associated with simvastatin and atorvastatin ADRs. Our study first linked statin ADRs and ABCG2 variants. Also, our study first showed importance of pharmacogenetic predisposition for developing fluvastatin ADRs.

Constitutive activation of the phosphoinositide-3-kinase (PI3K)/Akt signaling pathway is crucial for tumor growth and progression. As such, this pathway has been an enticing target for drug discovery. Although HS-173 is a potent PI3K inhibitor that halts cancer cell proliferation via G2/M cell cycle arrest, the resistance mechanisms to HS-173 have not been investigated. In this study, we investigated the susceptibility of HS-173 to efflux mediated by the multidrug efflux transporters ABCB1 and ABCG2, which are two of the most well-known ATP-binding cassette (ABC) transporters associated with the development of cancer multidrug resistance (MDR). We found that the overexpression of ABCB1 or ABCG2 significantly reduced the efficacy of HS-173 in human cancer cells. Our data show that the intracellular accumulation of HS-173 was substantially reduced by ABCB1 and ABCG2, affecting G2/M arrest and apoptosis induced by HS-173. More importantly, the efficacy of HS-173 in multidrug-resistant cancer cells could be recovered by inhibiting the drug-efflux function of ABCB1 and ABCG2. Taken together, our study has demonstrated that HS-173 is a substrate for both ABCB1 and ABCG2, resulting in decreased intracellular concentration of this drug, which may have implications for its clinical use.

The expression of the drug efflux pump ABCB1 correlates negatively with cancer survival, making the transporter an attractive target for therapeutic inhibition. In order to identify new inhibitors of ABCB1, we have exploited the cryo-EM structure of the protein to develop a pharmacophore model derived from the best docked conformations of a structurally diverse range of known inhibitors. The pharmacophore model was used to screen the Chembridge compound library. We identified six new potential inhibitors with distinct chemistry compared to the third-generation inhibitor tariquidar and with favourable lipophilic efficiency (LipE) and lipophilicity (CLogP) characteristics, suggesting oral bioavailability. These were evaluated experimentally for efficacy and potency using a fluorescent drug transport assay in live cells. The half-maximal inhibitory concentrations (IC50) of four of the compounds were in the low nanomolar range (1.35 to 26.4 nM). The two most promising compounds were also able to resensitise ABCB1-expressing cells to taxol. This study demonstrates the utility of cryo-electron microscopy structure determination for drug identification and design.

A limited number of studies are devoted to regulating TRIP6 expression in cancer. Hence, we aimed to unveil the regulation of TRIP6 expression in MCF-7 breast cancer cells (with high TRIP6 expression) and taxane-resistant MCF-7 sublines (manifesting even higher TRIP6 expression). We found that TRIP6 transcription is regulated primarily by the cyclic AMP response element (CRE) in hypomethylated proximal promoters in both taxane-sensitive and taxane-resistant MCF-7 cells. Furthermore, in taxane-resistant MCF-7 sublines, TRIP6 co-amplification with the neighboring ABCB1 gene, as witnessed by fluorescence in situ hybridization (FISH), led to TRIP6 overexpression. Ultimately, we found high TRIP6 mRNA levels in progesterone receptor-positive breast cancer and samples resected from premenopausal women.

The transport of drugs by efflux transporters in biomembranes limits their bioavailability and is a major determinant of drug resistance development by cancer cells and pathogens. A large number of chemically dissimilar drugs are transported, and despite extensive studies, the molecular determinants of substrate specificity are still not well understood. In this work, we explore the role of polar and non-polar interactions on the interaction of a homologous series of fluorescent amphiphiles with the efflux transporter P-glycoprotein. The interaction of the amphiphiles with P-glycoprotein is evaluated through effects on ATPase activity, efficiency in inhibition of [125I]-IAAP binding, and partition to the whole native membranes containing the transporter. The results were complemented with partition to model membranes with a representative lipid composition, and details on the interactions established were obtained from MD simulations. We show that when the total concentration of amphiphile is considered, the binding parameters obtained are apparent and do not reflect the affinity for P–gp. A new formalism is proposed that includes sequestration of the amphiphiles in the lipid bilayer and the possible binding of several molecules in P–gp’s substrate-binding pocket. The intrinsic binding affinity thus obtained is essentially independent of amphiphile hydrophobicity, highlighting the importance of polar interactions. An increase in the lipophilicity and amphiphilicity led to a more efficient association with the lipid bilayer, which maintains the non-polar groups of the amphiphiles in the bilayer, while the polar groups interact with P–gp’s binding pocket. The presence of several amphiphiles in this orientation is proposed as a mechanism for inhibition of P-pg function.

Multidrug resistance (MDR) has been extensively reported in colorectal cancer patients, which remains a major cause of chemotherapy failure. One of the critical mechanisms of MDR in colorectal cancer is the reduced intracellular drug level led by the upregulated expression of the ATP‐binding cassette (ABC) transporters, particularly, ABCB1/P‐gp. In this study, the CRISPR/Cas9 system was utilized to target ABCB1 in MDR colorectal cancer SW620/Ad300 cell line with ABCB1 overexpression. The results showed that stable knockout of ABCB1 gene by the CRISPR/Cas9 system was achieved in the MDR cancer cells. Reversal of MDR against ABCB1 chemotherapeutic drugs increased intracellular accumulation of [3H]‐paclitaxel accumulation, and decreased drug efflux activity was observed in MDR SW620/Ad300 cells after ABCB1 gene knockout. Further tests using the 3D multicellular tumor spheroid model suggested that deficiency in ABCB1 restrained tumor spheroid growth and restore sensitivity to paclitaxel in MDR tumor spheroids. Overall, the CRISPR/Cas9 system targeting the ABCB1 gene can be an effective approach to overcome ABCB1‐mediated MDR in colorectal cancer SW620/Ad300 cells., In this study, the CRISPR/Cas9 system was utilized to target ABCB1 in multidrug resistant (MDR) colorectal cancer SW620/Ad300 cell line with ABCB1 overexpression. Knockout of ABCB1 gene resulted in reversal of MDR against ABCB1 chemotherapeutic drugs, increased intracellular accumulation of [3H]‐paclitaxel accumulation, and decreased drug efflux activity in MDR colon cancer cells. In a 3D multicellular tumor spheroid model, deficiency in ABCB1 restrained tumor spheroid growth and restore sensitivity to paclitaxel in MDR tumor spheroids.

Docetaxel (DTX) is a mainstay in the treatment of metastatic prostate cancer. Failure of DTX therapy is often associated with multidrug resistance caused by overexpression of efflux membrane transporters of the ABC family such as the glycoprotein ABCB1. This study investigated multiple approaches targeting ABCB1 to resensitize DTX-resistant (DTXR) prostate cancer cell lines. In DU145 DTXR and PC-3 DTXR cells as well as age-matched parental controls, the expression of selected ABC transporters was analyzed by quantitative PCR, Western blot, flow cytometry and immunofluorescence. ABCB1 effluxing activity was studied using the fluorescent ABCB1 substrate rhodamine 123. The influence of ABCB1 inhibitors (elacridar, tariquidar), ABCB1-specific siRNA and inhibition of post-translational glycosylation on DTX tolerance was assessed by cell viability and colony formation assays. In DTXR cells, only ABCB1 was highly upregulated, which was accompanied by a strong effluxing activity and additional post-translational glycosylation of ABCB1. Pharmacological inhibition and siRNA-mediated knockdown of ABCB1 completely resensitized DTXR cells to DTX. Inhibition of glycosylation with tunicamycin affected DTX resistance partially in DU145 DTXR cells, which was accompanied by a slight intracellular accumulation and decreased effluxing activity of ABCB1. In conclusion, DTX resistance can be reversed by various strategies with small molecule inhibitors representing the most promising and feasible approach.

Graphical abstract, Introduction Nephrotic syndrome is a common pediatric kidney disease. Investigations on several genetic polymorphisms revealed an inconsistent influence on the resistance of patients to steroids. Objectives This study aimed to identify the association of ABCB1 (1236C > T, 2677G > T, 3435C > T), NR3C1 (rs10482634, rs6877893), and CYP3A5 (CYP3A5*3) gene polymorphism as well as sociodemographic and clinicopathological parameters with the risk of developing prednisolone resistance in pediatric patients with nephrotic syndrome. Methods A case-control analysis was performed on 180 nephrotic syndrome patients. Among them, 30 patients were classified as prednisolone resistant group, and 150 were classified as prednisolone sensitive group. Genotyping was performed by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Results No significant association of 1236C > T polymorphism with the risk of prednisolone resistance (p > 0.05) was found. The GT heterozygous of 2677G > T was found to be significantly associated with the development of prednisolone resistance (OR = 3.9, p = 0.034). In the case of 3435C > T, a statistically significant association was observed in TC heterozygous and TT mutant homozygous genotypes (OR = 0.38, p = 0.047; OR = 3.06, p = 0.038, respectively) with prednisolone resistance. For rs10482634 polymorphism, the AG heterozygous and AG+GG genotypes were significantly linked with prednisolone resistance (OR = 2.40, p = 0.033; OR = 2.36, p = 0.034, respectively). We found no association with the risk of prednisolone resistance with rs6877893 and CYP3A5*3 polymorphism (p > 0.05). CTC and TGT haplotypes of ABCB1 and GA haplotype of NR3C1 were also associated with the increased risk of pediatric prednisolone resistance (OR = 4.47, p = 0.0003; OR = 2.71, p = 0.03; and OR = 4.22, p = 0.022, consecutively). We also observed the correlation of different sociodemographic and clinicopathological factors with prednisolone resistance in pediatric nephrotic syndrome. Conclusion Our findings showed a significant association of ABCB1 and NR3C1 gene polymorphisms with prednisolone resistant pediatric nephrotic syndrome.

Background Tenofovir alafenamide fumarate (TAF) was approved for HBV treatment in China in 2018. Despite higher antiviral efficacy and less impact on renal function and bone mineral density, the pharmacokinetic profiles of TAF are highly variable. The objectives of this study were to investigate the pharmacokinetics of TAF in the Chinese population and explore the associations between TAF and genetic polymorphisms and non-genetic factors. Patients and Methods A total of 64 healthy Chinese subjects aged 18~65 years old were planned to enroll. According to the dietary intake status, the subjects were divided into two groups (n = 32 per group). The concentrations of TAF and tenofovir were measured by HPLC-MS/MS, and the single-nucleotide polymorphisms were analyzed by MALDI-TOF MS. Results All the enrolled participants (18–35 years) completed the clinical trial study. Similar to the results reported in other ethnic populations, the pharmacokinetic profiles of TAF and tenofovir were highly variable in the Chinese people, and the HFHC diet can significantly increase the systemic exposure of TAF. We determined both HFHC diet and rs7311358 (SLCO1B3) genotypes were independently associated with TAF AUC0-t, while HFHC diet, age and rs3740066 (ABCC2) variants were predictive of t1/2 of tenofovir (P < 0.05). The subjects with the AA genotype in rs7311358 had significantly higher TAF AUC0-t values (1.15 times) than those with a G allele, and the t1/2 of tenofovir in the rs3740066 TT genotype group was 1.23 times longer than that of CC genotype group. Furthermore, there was a trend of higher TAF AUC and shorter tenofovir t1/2 for the rs2032582 (ABCB1) T allele and rs3742106 (ABCC4) CC variant, respectively, although not statistically significant in the multiple linear regression analysis. Conclusion This study provided new evidence to suggest a critical link between both genetic and non-genetic factors and TAF pharmacokinetics in the Chinese people., Graphical Abstract

Xue Li,1,&ast; Xin-Yi Tan,2,&ast; Xue-Jun Cui,3 Ming Yang,1 Chao Chen,1 Xiao-Yun Chen2 1Phase I Clinical Research Laboratory of Shanghai LongHua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, People’s Republic of China; 2Department of Rheumatology of Shanghai LongHua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, People’s Republic of China; 3Institute of Spinal Disease, Shanghai University of Traditional Chinese Medicine, Shanghai, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Xiao-Yun ChenDepartment of Rheumatology of Shanghai LongHua Hospital, Shanghai University of Traditional Chinese Medicine, No. 725, South Wanping Road, Shanghai, 200032, People’s Republic of ChinaTel/Fax +86-21-64289981Email lh2396@shutcm.edu.cnChao ChenPhase I Clinical Research Laboratory of Shanghai LongHua Hospital, Shanghai University of Traditional Chinese Medicine, No. 725, South Wanping Road, Shanghai, 200032, People’s Republic of ChinaTel +86-21-64385700-9707Fax +86-21-64289981Email lhchenchao@shutcm.edu.cnBackground: Tenofovir alafenamide fumarate (TAF) was approved for HBV treatment in China in 2018. Despite higher antiviral efficacy and less impact on renal function and bone mineral density, the pharmacokinetic profiles of TAF are highly variable. The objectives of this study were to investigate the pharmacokinetics of TAF in the Chinese population and explore the associations between TAF and genetic polymorphisms and non-genetic factors.Patients and Methods: A total of 64 healthy Chinese subjects aged 18∼ 65 years old were planned to enroll. According to the dietary intake status, the subjects were divided into two groups (n = 32 per group). The concentrations of TAF and tenofovir were measured by HPLC-MS/MS, and the single-nucleotide polymorphisms were analyzed by MALDI-TOF MS.Results: All the enrolled participants (18– 35 years) completed the clinical trial study. Similar to the results reported in other ethnic populations, the pharmacokinetic profiles of TAF and tenofovir were highly variable in the Chinese people, and the HFHC diet can significantly increase the systemic exposure of TAF. We determined both HFHC diet and rs7311358 (SLCO1B3) genotypes were independently associated with TAF AUC0-t, while HFHC diet, age and rs3740066 (ABCC2) variants were predictive of t1/2 of tenofovir (P < 0.05). The subjects with the AA genotype in rs7311358 had significantly higher TAF AUC0-t values (1.15 times) than those with a G allele, and the t1/2 of tenofovir in the rs3740066 TT genotype group was 1.23 times longer than that of CC genotype group. Furthermore, there was a trend of higher TAF AUC and shorter tenofovir t1/2 for the rs2032582 (ABCB1) T allele and rs3742106 (ABCC4) CC variant, respectively, although not statistically significant in the multiple linear regression analysis.Conclusion: This study provided new evidence to suggest a critical link between both genetic and non-genetic factors and TAF pharmacokinetics in the Chinese people.Keywords: tenofovir alafenamide fumarate, pharmacokinetics, SLCO1B3, ABCB1, ABCC2, ABCC4

Background Dyslipidemia is a predisposing factor for coronary heart disease (CHD). High-intensity statin therapy is recommended as secondary prevention. ABCB1 and SLCO1B1 genes influence the efficacy and safety of statins. Xinjiang is a multi-ethnic area; however, little is known about the prevalence of dyslipidemia and gene polymorphisms of ABCB1 and SLCO1B1 in minority groups with CHD. Objective To measure levels of lipid and apolipoprotein and the prevalence of dyslipidemia and gene polymorphisms of ABCB1, SLCO1B1 in Han, Uygur, Kazak, Hui, Tatar, Kirgiz, and Sibe populations with CHD in Xinjiang. Methods This descriptive retrospective study compares lipid levels in ethnic groups using Kruskal-Wallis test or analysis of variance. The study compared gene polymorphisms and the prevalence of dyslipidemia among different ethnic groups using the chi-square test. The lipid profiles in plasma were measured before lipid-lowering therapy using commercially available kits. Genotyping of SLCO1B1 and ABCB1 variants was performed using sequencing by hybridization. Results A total of 2218 patients were successfully screened, including 1044 Han, 828 Uygur, 113 Kazak, 138 Hui, 39 Tatar, 36 Kirgiz, and 20 Sibe patients. The overall mean age was 61.8 ± 10.8 years, and 72.5% of participants were male. Dyslipidemia prevalence in these ethnic groups was 42.1, 49.8, 52.2, 40.6, 48.7, 41.7, and 45.0%, respectively. The prevalence of dyslipidemia, high total cholesterol (TC), high triglycerides (TG), and high low density lipoprotein cholesterol (LDL-C) differed significantly among the groups (P = 0.024; P < 0.001; P < 0.001; P < 0.001, respectively). For the Han group, high LDL-C, high TC, and high TG prevalence differed significantly by gender (P = 0.001, P = 0.022, P = 0.037, respectively). The prevalence of high TC, high TG, and low high density lipoprotein cholesterol (HDL-C) differed significantly by gender in the Uygur group (P = 0.006, P = 0.004, P < 0.001, respectively). The prevalence of high TC in Hui patients significantly differed by gender (P = 0.043). These findings suggest that polymorphisms in ABCB1 and C3435T differ significantly across ethnicities (P < 0.001). Conclusions The prevalences of dyslipidemia, high TC, high TG, and high LDL-C in Han, Uygur, Kazak, Hui, Tatar, Kirgiz, and Sibe CHD patients in Xinjiang differed concerning ethnicity. Ethnic, gender, and lifestyle were the key factors that affected the lipid levels of the population. The prevalence of polymorphisms of ABCB1 and C3435T significantly differed across ethnicities. These findings will aid the selection of precision lipid-lowering medications and prevention and treatment of CHD according to ethnicity in Xinjiang.

Background: The ABCB1 gene is responsible for resistance to various cytotoxic drugs. The product of the ABCB1 gene, P-glycoprotein (P-gp), acts as a transmembrane pump and influences the action of many drugs. More than 40 SNPs of the ABCB1 gene that alter the expression of P-gp have been identified. The ABCB1 rs1045642 SNP, designated as C3435T (C-the wild-type allele, T-the variant allele), correlates with the activity of P-gp. The aim of our research was to study the distribution of alleles and genotypes of the ABCB1 C3435T polymorphism in Yakuts, in comparison with other human populations. Methods and Results: The studied cohort included 149 healthy Yakut volunteers (36 men and 113 women). The average age of participants was 30.67±0.06 years. The ABCB1 gene is a highly polymorphic gene; the allele frequency of the C3435T polymorphism differs widely among the studied populations. The frequency of the mutant T-allele among the Yakuts was 51% .In the studied group of Yakuts, we revealed the prevalence of the heterozygous CT genotype (75.8%). The Yakuts have a relatively low frequency of CC (10.7%) and TT (13.4%) genotypes. This preliminary study did not include the objective of proving the relationship between the ABCB1 C3435T polymorphism and addictive disorders in Yakuts. The further search for functional polymorphisms of the ABCB1 gene and associations with addictive behavior using a systematic approach on larger samples is of great practical importance.

Opioids like morphine are commonly used to treat moderate or severe (cancer) pain. Importantly, the nonmedical use of prescription opioid analgesics can lead to opioid use disorder (OUD), which is associated with high morbidity and mortality rates. Of note, one can also initially become addicted to opioids without first being exposed to prescription opioids, through the use of illicitly obtained opioids. Opioid agonist treatment with methadone, buprenorphine(-naloxone), or slow-release morphine is the most common evidence-based treatment modality for individuals with OUD. Still, not all patients are successfully recruited or retained in these medication therapies. Thus, several countries, including the Netherlands, offer pharmaceutical-grade heroin (diacetylmorphine; diamorphine) as a maintenance treatment option for those individuals (heroin-assisted treatment or HAT). Interestingly, psychedelic substances, such as ibogaine, have been associated with the alleviation of several substance use disorders and may hold promise as potential treatments for OUD. Shifting from cancer-related analgesia and palliative care to pharmacological cancer treatment, we have also studied an inhibitor of poly(ADP-ribose) polymerases (PARPs) 1 and 2, two enzymes essential to normal DNA repair activities. PARP inhibitors have revolutionized the treatment of women with certain forms of advanced ovarian cancer. Presently, four PARP inhibitors are approved for clinical use, including niraparib, which is also currently being tested in multiple clinical trials for treatment of other types of cancer than ovarian, such as intracranial tumors. It is well established that (trans)membrane transporters play a role in drug disposition, therapeutic efficacy, and adverse drug reaction. Clinical-pharmacokinetic drug-drug interaction studies have also suggested that transporters often work together with drug-metabolizing enzymes in controlling drug absorption and elimination. Consequently, the effects of changes in transport activity due to environmental factors (e.g., drug interaction) or genetic variation should be considered. This is especially relevant when predicting potential changes in the systemic exposure of drugs, which can result in clinically relevant (pharmacodynamic) effects. In this dissertation, using various genetically modified mouse models, we investigated the impact of efflux (ABCB1 and ABCG2) and uptake transporters (OATP1A/1B/2B1) and cytochrome P450 3A (CYP3A) enzymes on the pharmacokinetics and tissue distribution of two opioids (morphine and heroin), the psychedelic compound ibogaine, and the PARP1/2 inhibitor niraparib, plus their relevant metabolites. Moreover, we further demonstrated the usefulness of knockout and humanized transgenic mouse models to investigate the pharmacological properties of the studied drug transporters and drug-metabolizing enzymes. All in all, we hope that the obtained knowledge from the studies described in this dissertation will prompt further (pre-)clinical research and help improve both the safety and efficacy profiles of the studied compounds, especially when considering a broader clinical application.

Opioids like morphine are commonly used to treat moderate or severe (cancer) pain. Importantly, the nonmedical use of prescription opioid analgesics can lead to opioid use disorder (OUD), which is associated with high morbidity and mortality rates. Of note, one can also initially become addicted to opioids without first being exposed to prescription opioids, through the use of illicitly obtained opioids. Opioid agonist treatment with methadone, buprenorphine(-naloxone), or slow-release morphine is the most common evidence-based treatment modality for individuals with OUD. Still, not all patients are successfully recruited or retained in these medication therapies. Thus, several countries, including the Netherlands, offer pharmaceutical-grade heroin (diacetylmorphine; diamorphine) as a maintenance treatment option for those individuals (heroin-assisted treatment or HAT). Interestingly, psychedelic substances, such as ibogaine, have been associated with the alleviation of several substance use disorders and may hold promise as potential treatments for OUD. Shifting from cancer-related analgesia and palliative care to pharmacological cancer treatment, we have also studied an inhibitor of poly(ADP-ribose) polymerases (PARPs) 1 and 2, two enzymes essential to normal DNA repair activities. PARP inhibitors have revolutionized the treatment of women with certain forms of advanced ovarian cancer. Presently, four PARP inhibitors are approved for clinical use, including niraparib, which is also currently being tested in multiple clinical trials for treatment of other types of cancer than ovarian, such as intracranial tumors. It is well established that (trans)membrane transporters play a role in drug disposition, therapeutic efficacy, and adverse drug reaction. Clinical-pharmacokinetic drug-drug interaction studies have also suggested that transporters often work together with drug-metabolizing enzymes in controlling drug absorption and elimination. Consequently, the effects of changes in transport activity due to environmental factors (e.g., drug interaction) or genetic variation should be considered. This is especially relevant when predicting potential changes in the systemic exposure of drugs, which can result in clinically relevant (pharmacodynamic) effects. In this dissertation, using various genetically modified mouse models, we investigated the impact of efflux (ABCB1 and ABCG2) and uptake transporters (OATP1A/1B/2B1) and cytochrome P450 3A (CYP3A) enzymes on the pharmacokinetics and tissue distribution of two opioids (morphine and heroin), the psychedelic compound ibogaine, and the PARP1/2 inhibitor niraparib, plus their relevant metabolites. Moreover, we further demonstrated the usefulness of knockout and humanized transgenic mouse models to investigate the pharmacological properties of the studied drug transporters and drug-metabolizing enzymes. All in all, we hope that the obtained knowledge from the studies described in this dissertation will prompt further (pre-)clinical research and help improve both the safety and efficacy profiles of the studied compounds, especially when considering a broader clinical application.

Opioids like morphine are commonly used to treat moderate or severe (cancer) pain. Importantly, the nonmedical use of prescription opioid analgesics can lead to opioid use disorder (OUD), which is associated with high morbidity and mortality rates. Of note, one can also initially become addicted to opioids without first being exposed to prescription opioids, through the use of illicitly obtained opioids. Opioid agonist treatment with methadone, buprenorphine(-naloxone), or slow-release morphine is the most common evidence-based treatment modality for individuals with OUD. Still, not all patients are successfully recruited or retained in these medication therapies. Thus, several countries, including the Netherlands, offer pharmaceutical-grade heroin (diacetylmorphine; diamorphine) as a maintenance treatment option for those individuals (heroin-assisted treatment or HAT). Interestingly, psychedelic substances, such as ibogaine, have been associated with the alleviation of several substance use disorders and may hold promise as potential treatments for OUD. Shifting from cancer-related analgesia and palliative care to pharmacological cancer treatment, we have also studied an inhibitor of poly(ADP-ribose) polymerases (PARPs) 1 and 2, two enzymes essential to normal DNA repair activities. PARP inhibitors have revolutionized the treatment of women with certain forms of advanced ovarian cancer. Presently, four PARP inhibitors are approved for clinical use, including niraparib, which is also currently being tested in multiple clinical trials for treatment of other types of cancer than ovarian, such as intracranial tumors. It is well established that (trans)membrane transporters play a role in drug disposition, therapeutic efficacy, and adverse drug reaction. Clinical-pharmacokinetic drug-drug interaction studies have also suggested that transporters often work together with drug-metabolizing enzymes in controlling drug absorption and elimination. Consequently, the effects of changes in transport activity due to environmental factors (e.g., drug interaction) or genetic variation should be considered. This is especially relevant when predicting potential changes in the systemic exposure of drugs, which can result in clinically relevant (pharmacodynamic) effects. In this dissertation, using various genetically modified mouse models, we investigated the impact of efflux (ABCB1 and ABCG2) and uptake transporters (OATP1A/1B/2B1) and cytochrome P450 3A (CYP3A) enzymes on the pharmacokinetics and tissue distribution of two opioids (morphine and heroin), the psychedelic compound ibogaine, and the PARP1/2 inhibitor niraparib, plus their relevant metabolites. Moreover, we further demonstrated the usefulness of knockout and humanized transgenic mouse models to investigate the pharmacological properties of the studied drug transporters and drug-metabolizing enzymes. All in all, we hope that the obtained knowledge from the studies described in this dissertation will prompt further (pre-)clinical research and help improve both the safety and efficacy profiles of the studied compounds, especially when considering a broader clinical application.

Nutritional status and gene polymorphisms of one-carbon metabolism confer a well-known interaction that in pregnant women may affect embryo viability and the health of the newborn. Folate metabolism directly impacts nucleotide synthesis and methylation, which is of increasing interest in the reproductive medicine field. Studies assessing the genetic influence of folate metabolism on IVF treatments have currently been performed in women using their own oocytes. Most of these patients seeking to have a child or undergoing IVF treatments are advised to preventively intake folate supplies that restore known metabolic imbalances, but the treatments could lead to the promotion of specific enzymes in specific women, depending on their genetic variance. In the present study, we assess the influence of candidate gene variants related to folate metabolism, such as Serine Hydroxymethyltransferase 1 SHMT1 (rs1979276 and rs1979277), Betaine-Homocysteine S-Methyltransferase BHMT (rs3733890), Methionine synthase reductase MTRR (rs1801394), Methylenetetrahydrofolate reductase MTHFR (rs1801131 and rs1801133), methionine synthase MTR (rs12749581), ATP Binding Cassette Subfamily B Member 1 ABCB1 (rs1045642) and folate receptor alpha FOLR1 (rs2071010) on the success of IVF treatment performed in women being recipients of donated oocytes. The implication of such gene variants seems to have no direct impact on pregnancy consecution after IVF; however, several gene variants could influence pregnancy loss events or pregnancy maintenance, as consequence of folic acid fortification.

Nutritional status and gene polymorphisms of one-carbon metabolism confer a well-known interaction that in pregnant women may affect embryo viability and the health of the newborn. Folate metabolism directly impacts nucleotide synthesis and methylation, which is of increasing interest in the reproductive medicine field. Studies assessing the genetic influence of folate metabolism on IVF treatments have currently been performed in women using their own oocytes. Most of these patients seeking to have a child or undergoing IVF treatments are advised to preventively intake folate supplies that restore known metabolic imbalances, but the treatments could lead to the promotion of specific enzymes in specific women, depending on their genetic variance. In the present study, we assess the influence of candidate gene variants related to folate metabolism, such as Serine Hydroxymethyltransferase 1 SHMT1 (rs1979276 and rs1979277), Betaine-Homocysteine S-Methyltransferase BHMT (rs3733890), Methionine synthase reductase MTRR (rs1801394), Methylenetetrahydrofolate reductase MTHFR (rs1801131 and rs1801133), methionine synthase MTR (rs12749581), ATP Binding Cassette Subfamily B Member 1 ABCB1 (rs1045642) and folate receptor alpha FOLR1 (rs2071010) on the success of IVF treatment performed in women being recipients of donated oocytes. The implication of such gene variants seems to have no direct impact on pregnancy consecution after IVF; however, several gene variants could influence pregnancy loss events or pregnancy maintenance, as consequence of folic acid fortification.

Objectives: The purpose of our study is to investigate the effects of apolipoprotein B (APOB) and APOE gene polymorphisms on bleeding complications in patients receiving direct oral anticoagulants (DOACs). Methods: A total of 16 single nucleotide polymorphisms (SNPs) in 468 patients were genotyped. Six SNPs of ABCB1 (rs3842, rs1045642, rs2032582, rs1128503, rs3213619, and rs3747802), one SNP of CYP3A5 (rs776746), seven SNPs of APOB (rs1042034, rs2163204, rs693, rs679899, rs13306194, rs13306198, and rs1367117), and two SNPs of APOE (rs429358 and rs7412) were analyzed by a TaqMan genotyping assay. Multivariable logistic regression analysis with selected variables was performed for the construction of a risk scoring system. Two risk scoring systems were compared (demographic factors only vs. demographic factors and genetic factors). Results: In the multivariable analyses, two models were constructed; only demographic factors were included in Model I and both demographic factors and genetic factors in Model II. Rivaroxaban and anemia showed significant association with bleeding in both models. Additionally, ABCB1 rs3842 variant homozygote carriers (CC) and APOB rs13306198 variant allele carriers (AG, AA) had a higher risk of bleeding risk compared with that of wild-type allele carriers (TT, TC) and wild-type homozygote carriers (GG), respectively. Whereas the area under the receiver operating characteristic curve (AUROC) value using demographic factors only was 0.65 (95% confidence interval (CI): 0.56–0.74), the AUROC increased to 0.72 by adding genetic factors (95% CI: 0.65–0.80). The predicted bleeding risks of bleeding in patients with 0, 1, 2, 3, 4, 5, 6, 7 and 8 points from the logistic regression curve were 0.8%, 2.0%, 5.4%, 5.2%, 12.5%, 26.9%, 47.0%, 64.3% and 82.3%, respectively. Conclusions: The study results can be used for enhancing individualized treatment strategies in patients taking DOACs, helping clinicians predict the bleeding risk.

Genetic influences on acute responses to psychoactive drugs may contribute to individual variability in addiction risk. ABCB1 is a human gene that encodes P-glycoprotein, an ATP-dependent efflux pump that may influence the pharmacokinetics of delta-9-tetrahydrocannabinol (THC), the primary psychoactive component of cannabis. Using data from 48 young adults (aged 19–25 years) reporting 1–4 days of cannabis use per week who completed a placebo-controlled human laboratory experiment, we tested the hypothesis that the rs2235048 polymorphism of ABCB1 would influence acute responses to smoked cannabis. C-allele carriers reported on average greater frequency of weekly cannabis use compared to the TT genotype carriers (TC/CC mean ± SEM = 2.74 ± 0.14, TT = 1.85 ± 0.24, p = 0.004). After smoking a single cannabis cigarette to their desired high, C-allele carriers had higher area-under-the-curve (AUC) of both THC metabolites (11-OH-THC TC/CC = 7.18 ± 9.64, TT = 3.28 ± 3.40, p = 0.05; THC-COOH TC/CC = 95.21 ± 116.12, TT = 45.92 ± 42.38, p = 0.043), and these results were impact by self-reported ethnicity. There were no significant differences in self-reported subjective drug effects except for a greater AUC of visual analogue scale rating of drug liking (TC/CC = 35,398.33 ± 37,233.72, TT = 15,895.56 ± 13,200.68, p = 0.017). Our preliminary findings suggest that further work in a larger sample should investigate whether human ABCB1 influences cannabis-related phenotypes and plays a role in the risk of developing a cannabis use disorder.

We investigated genetic determinants of single-dose simvastatin pharmacokinetics in a prospective study of 170 subjects and a retrospective cohort of 59 healthy volunteers. In a microarray-based genomewide association study with the prospective data, the SLCO1B1 c.521T>C (p.Val174Ala, rs4149056) single nucleotide variation showed the strongest, genomewide significant association with the area under the plasma simvastatin acid concentration-time curve (AUC; P = 6.0 x 10(-10)). Meta-analysis with the retrospective cohort strengthened the association (P = 1.6 x 10(-17)). In a stepwise linear regression candidate gene analysis among all 229 participants, SLCO1B1 c.521T>C (P = 1.9 x 10(-13)) and CYP3A4 c.664T>C (p.Ser222Pro, rs55785340, CYP3A4*2, P = 0.023) were associated with increased simvastatin acid AUC. Moreover, the SLCO1B1 c.463C>A (p.Pro155Thr, rs11045819, P = 7.2 x 10(-6)) and c.1929A>C (p.Leu643Phe, rs34671512, P = 5.3 x 10(-4)) variants associated with decreased simvastatin acid AUC. Based on these results and the literature, we classified the volunteers into genotype-predicted OATP1B1 and CYP3A4 phenotype groups. Compared with the normal OATP1B1 function group, simvastatin acid AUC was 273% larger in the poor (90% confidence interval (CI), 137%, 488%; P = 3.1 x 10(-6)), 40% larger in the decreased (90% CI, 8%, 83%; P = 0.036), and 67% smaller in the highly increased function group (90% CI, 46%, 80%; P = 2.4 x 10(-4)). Intermediate CYP3A4 metabolizers (i.e., heterozygous carriers of either CYP3A4*2 or CYP3A4*22 (rs35599367)), had 87% (90% CI, 39%, 152%, P = 6.4 x 10(-4)) larger simvastatin acid AUC than normal metabolizers. These data suggest that in addition to no function SLCO1B1 variants, increased function SLCO1B1 variants and reduced function CYP3A4 variants may affect the pharmacokinetics, efficacy, and safety of simvastatin. Care is warranted if simvastatin is prescribed to patients carrying decreased function SLCO1B1 or CYP3A4 alleles.

Adenosine triphosphate–binding cassette subfamily B member 1 (ABCB1), also known as permeability glycoprotein, multidrug-resistant protein 1, or cluster of differentiation 243 (CD243), is a crucial protein for purging foreign substances from cells. The functions of ABCB1 have been investigated extensively for their roles in cancer, stem cells, and drug resistance. Abundant pharmacogenetic studies have been conducted on ABCB1 and its association with treatment responsiveness to various agents, particularly chemotherapeutic and immunomodulatory agents. However, its functions in the skin and implications on dermatotherapeutics are far less reported. In this article, we reviewed the roles of ABCB1 in dermatology. ABCB1 is expressed in the skin and its appendages during drug delivery and transport. It is associated with treatment responsiveness to various agents, including topical steroids, methotrexate, cyclosporine, azathioprine, antihistamines, antifungal agents, colchicine, tacrolimus, ivermectin, tetracycline, retinoid acids, and biologic agents. Moreover, genetic variation in ABCB1 is associated with the pathogenesis of several dermatoses, including psoriasis, atopic dermatitis, melanoma, bullous pemphigoid, Behcet disease, and lichen planus. Further investigation is warranted to elucidate the roles of ABCB1 in dermatology and the possibility of enhancing therapeutic efficacy through ABCB1 manipulation.

Accurate detection of ATP-binding cassette drug transporter ABCB1 expression is imperative for precise identification of drug-resistant tumors. Existing detection methods fail to provide the necessary molecular details regarding the functional state of the transporter. Photoimmunoconjugates are a unique class of antibody–dye conjugates for molecular diagnosis and therapeutic treatment. However, conjugating hydrophobic photosensitizers to hydrophilic antibodies is quite challenging. Here, we devise a photoimmunoconjugate that combines a clinically approved benzoporphyrin derivative (BPD) photosensitizer and the conformational-sensitive UIC2 monoclonal antibody to target functionally active human ABCB1 (i.e., ABCB1 in the inward-open conformation). We show that PEGylation of UIC2 enhances the BPD conjugation efficiency and reduces the amount of non-covalently conjugated BPD molecules by 17%. Size exclusion chromatography effectively separates the different molecular weight species found in the UIC2–BPD sample. The binding of UIC2–BPD to ABCB1 was demonstrated in lipidic nanodiscs and ABCB1-overexpressing triple negative breast cancer (TNBC) cells. UIC2–BPD was found to retain the conformation sensitivity of UIC2, as the addition of ABCB1 modulators increases the antibody reactivity in vitro. Thus, the inherent fluorescence capability of BPD can be used to label ABCB1-overexpressing TNBC cells using UIC2–BPD. Our findings provide insight into conjugation of hydrophobic photosensitizers to conformation-sensitive antibodies to target proteins expressed on the surface of cancer cells.

Context: It was found that flavonoids and frankincense exert anti-cancer effect through their antioxidant and anti-inflammatory activities. Aims: To evaluate the cytotoxic effect against MCF-7 cells of flavonoids isolated from Physalis pubescens L., frankincense ethanol extract and the combined therapy with epirubicin to reduce the resistance and the side effects. Methods: MTT assay against MCF-7 was carried out for rutin, quercitrin, myricitrin and frankincense. The compound or extract with the best anti-cancer effect was tested against WI-38 cells. 50% inhibitory concentration (IC50) of the different treatments and the combined therapy with epirubicin against MCF-7 was determined. Assessment the effect on expression of ABCB1, TGF-β1 and ATG7 genes was done by RT-qPCR. Results: Isolation and identification of myricitrin from leaves of Physalis pubescens L. was carried out for the first time. IC50 (µg/mL) regarding MCF-7 cells was of epirubicin (0.8 ± 0.052), rutin (350.16 ± 1.241), quercitrin (259.6 ± 1.45), myricitrin (114.0 ± 0.517), frankincense ethanol extract (86.8 ± 0.91), combined epirubicin + myricitrin (EM) (0.37 ± 0.087), combined epirubicin + frankincense (EF) (0.50 ± 0.1732). The IC50 µg/mL regarding WI-38 cells was of epirubicin (1.26 ± 0.0057), myricitrin (462.0 ± 1.062) and frankincense (299.5 ± 1.32). All assays were done at 48 h time interval. Myricitrin and EM reduced ABCB1 expression and upregulated expression of TGF-β1 and ATG7 genes. Frankincense and EF downregulated expression of ABCB1, TGF-β1 and ATG7 genes. Conclusions: Myricitrin and frankincense would be a promising adjuvant therapy to improve epirubicin anticancer activity with minimal adverse effect.

Introduction Although ticagrelor and prasugrel remain the standard antiplatelet treatments in acute coronary syndrome (ACS), numerous patients still present with indications for clopidogrel use. Aim We aimed to assess the levels of clopidogrel active metabolite and to evaluate the effect of the drug on platelet inhibition in patients with ACS as compared with those with stable coronary disease. Patients were assessed for the presence of the most common genetic polymorphisms that reduce the absorption (ABCB1) and activation (CYP2C19*2 and CYP2C19*3) of clopidogrel to exclude the effect of genetic variability on drug concentrations and activity. Material and methods This single-center, open-label, prospective study included 199 patients hospitalized due to ST-segment elevation myocardial infarction (STEMI) or non-STEMI (NSTEMI) in Killip class I-III, who underwent percutaneous coronary intervention. The control group included 22 patients with stable coronary artery disease. Results The mean (SD) levels of active clopidogrel were 17.1 (12.3) ng/ml in controls and 16.4 (12.0) ng/ml in the whole study group (p < 0.68). No differences were noted in clopidogrel levels between patients with STEMI and NSTEMI (mean (SD), 17.6 (2.3) ng/ml and 15.1 (11.5) ng/ml; p < 0.45) or between STEMI and NSTEMI groups and controls (p < 0.38 and p < 0.61, respectively). No effect of ABCB1 or CYP2C19 polymorphism was observed in the study subgroups. Conclusions We concluded that ACS does not affect the levels of clopidogrel active metabolite or platelet inhibition in patients in Killip class I-III with or without CYP2C19 or ABCB1 gene polymorphisms.

Multidrug resistance (MDR) mediated by ATP binding cassette subfamily B member 1 (ABCB1) is significantly hindering effective cancer chemotherapy. However, currently, no ABCB1-inhibitory drugs have been approved to treat MDR cancer clinically, mainly due to the inhibitor specificity, toxicity, and drug interactions. Here, we reported that three polyoxypregnanes (POPs) as the most abundant constituents of Marsdenia tenacissima (M. tenacissima) were novel ABCB1-modulatory pro-drugs, which underwent intestinal microbiota-mediated biotransformation in vivo to generate active metabolites. The metabolites at non-toxic concentrations restored chemosensitivity in ABCB1-overexpressing cancer cells via inhibiting ABCB1 efflux activity without changing ABCB1 protein expression, which were further identified as specific non-competitive inhibitors of ABCB1 showing multiple binding sites within ABCB1 drug cavity. These POPs did not exhibit ABCB1/drug metabolizing enzymes interplay, and their repeated administration generated predictable pharmacokinetic interaction with paclitaxel without obvious toxicity in vivo. We further showed that these POPs enhanced the accumulation of paclitaxel in tumors and overcame ABCB1-mediated chemoresistance. The results suggested that these POPs had the potential to be developed as safe, potent, and specific pro-drugs to reverse ABCB1-mediated MDR. Our work also provided scientific evidence for the use of M. tenacissima in combinational chemotherapy., Graphical abstract Type I polyoxypregnanes (POPs) as prodrugs can be biotransformed by gut microbiota to form active metabolites (type II POPs) that are specific, safe, and potent non-competitive inhibitors of ABCB1, showing unique mechanisms to reverse ABCB1-mediated cancer MDR.Image 1

The multidrug transporter ABCB1 (MDR1, Pgp) plays an important role in the absorption, distribution, metabolism, and elimination of a wide range of pharmaceutical compounds. Functional investigation of the ABCB1 expression is also essential in many diseases, including drug-resistant cancer, inflammatory conditions, or Alzheimer disease. In this study, we examined the potential interaction of the ABCB1 multidrug transporter with a group of commercially available viability dyes that are generally considered not to penetrate into intact cells. Here, we demonstrate that the slow cellular accumulation of TO-PRO™-1 (TP1) or TO-PRO™-3 (TP3) was strongly inhibited by ABCB1-dependent dye extrusion. TP1/3 dye accumulation was not affected by the presence of ABCC1 or ABCG2, while this uptake was increased to the level in the ABCB1-negative cells by a specific P-glycoprotein inhibitor, Tariquidar. We suggest that TP compounds can be used as highly sensitive, selective, non-toxic, and stable dyes to examine the functional expression and properties of the ABCB1 multidrug transporter, especially in microplate-based high-throughput flow cytometry assays. In addition, we demonstrate the applicability of the TP dyes to efficiently select and separate even a very low number of Pgp-expressing intact cells.

Objective: Due to widespread presence and exposure to environmental pollutants, structural and functional changes in membrane transporters could occur, leading to plasental transport of these compounds. In this study, the effects of PCBs on SLC abd ABCB1 membrane transport molecules were evaluated. Materials and Methods: Hemochorial structured human placenta and endotheliochorial structured dog placenta were analyzed for 28 pollutants (PCB, PBDE, PAH and Organochlorines) using GC-MS. The expression profile of the placental whole genome were investigated with RNAseq, and in silico (molecular chelation) and in vitro (SLC and ABCB1 mRNA expression in the placental cell line HTR8/SVneo treated with PCB 101, PCB118) were evaluated. Results: PCB101 826.4μg/kg in one sample out of 60 samples tested; In 23 samples, PCB118 was found to be between 0.14 and 41.9μg/kg. In the bioinformatics findings, there were differences in 742 genes between PCB positive and negative samples in 55 samples that were sequenced (p, Amaç: Çevresel kirletici maruziyetine bağlı olarak işlevselliği değişen ve bozulan membran transportları nedeniyle, bu maddeler plasental bariyeri geçerek plasental kan dolaşımına geçebilmektedir. Çalışmada, çevresel kirleticilerin bu transport proteinleriyle etkileşimlerinin moleküler boyutta incelenmesi amaçlanmaktadır. Gereç ve Yöntem: Araştırma kapsamında hemokoryal yapıya sahip insan ve endotelyokoryal yapıya sahip köpek plasentasında; 28 kirleticinin analizi GC-MS ile yapılmış (PCB, PBDE, PAH ve Organik klorlu pestisitler); RNAseq ile plasental tüm genom ifade profili araştırılmış, in siliko (moleküler kenetleme) ve in vitro (PCB 101, PCB118 uygulanan plasental hücre hattı HTR8/SVneo’da SLC ve ABCB1 mRNA ifadesi) değerlendirilmiştir. Bulgular: Test edilen 60 örnek içerisinde bir örnekte PCB101 826.4μg/kg; 23 örnekte ise PCB118 0.14 ile 41,9μg/kg arasında bulundu. Biyoinformatik bulgularda sekans analizi yapılan 55 numunede PCB pozitif ve negatif numuneler arasında 742 gende farklılık bulundu (p

A number of detoxification systems with broad substrate specificity, including drug transporters and drug-metabolizing enzymes, can protect the body from various toxins, and dramatically influence drug absorption, metabolism, distribution and elimination (ADME) processes, as well as in some cases physiological homeostasis. In Part I of this thesis, in view of the likely importance of the Carboxylesterase 2 enzyme in pharmacological and physiological processes, we generated and characterized several CES2-related genetically modified mouse models. We then demonstrated the value of these mouse models to investigate the pharmacological and physiological functions of the CES2 enzyme complex. In Part II of this thesis we explored and revealed the roles (especially in the blood-brain-barrier) of several drug transporters (ABCB1, ABCG2 and OATP1A/1B) and the drug-metabolizing CYP3A enzymes in pharmacokinetic behavior of several anti-tumor small-molecule inhibitors, as well as related drug-drug interaction effects. We believe that the obtained new mouse models and pharmacological and physiological insights will provide further useful information and support for improving drug discovery and development, and eventually clinical-therapeutic application regimens.

A number of detoxification systems with broad substrate specificity, including drug transporters and drug-metabolizing enzymes, can protect the body from various toxins, and dramatically influence drug absorption, metabolism, distribution and elimination (ADME) processes, as well as in some cases physiological homeostasis. In Part I of this thesis, in view of the likely importance of the Carboxylesterase 2 enzyme in pharmacological and physiological processes, we generated and characterized several CES2-related genetically modified mouse models. We then demonstrated the value of these mouse models to investigate the pharmacological and physiological functions of the CES2 enzyme complex. In Part II of this thesis we explored and revealed the roles (especially in the blood-brain-barrier) of several drug transporters (ABCB1, ABCG2 and OATP1A/1B) and the drug-metabolizing CYP3A enzymes in pharmacokinetic behavior of several anti-tumor small-molecule inhibitors, as well as related drug-drug interaction effects. We believe that the obtained new mouse models and pharmacological and physiological insights will provide further useful information and support for improving drug discovery and development, and eventually clinical-therapeutic application regimens.

A number of detoxification systems with broad substrate specificity, including drug transporters and drug-metabolizing enzymes, can protect the body from various toxins, and dramatically influence drug absorption, metabolism, distribution and elimination (ADME) processes, as well as in some cases physiological homeostasis. In Part I of this thesis, in view of the likely importance of the Carboxylesterase 2 enzyme in pharmacological and physiological processes, we generated and characterized several CES2-related genetically modified mouse models. We then demonstrated the value of these mouse models to investigate the pharmacological and physiological functions of the CES2 enzyme complex. In Part II of this thesis we explored and revealed the roles (especially in the blood-brain-barrier) of several drug transporters (ABCB1, ABCG2 and OATP1A/1B) and the drug-metabolizing CYP3A enzymes in pharmacokinetic behavior of several anti-tumor small-molecule inhibitors, as well as related drug-drug interaction effects. We believe that the obtained new mouse models and pharmacological and physiological insights will provide further useful information and support for improving drug discovery and development, and eventually clinical-therapeutic application regimens.

Direktni oralni antikoagulansi (DOAK) posljednjih su godina pokazali rastući trend propisivanja zbog povoljne farmakokinetike i farmakodinamike bez potrebe za rutinskim nadzorom koagulacije. Svoj antikoagulantni učinak ostvaruju izravnom inhibicijom trombina (dabigatran) ili izravnom inhibicijom aktiviranog čimbenika X (rivaroksaban, apiksaban i edoksaban). Iako DOAK-i stupaju u manje interakcija s drugim lijekovima u usporedbi s varfarinom, kombinacija DOAK-a i mnogih lijekova zahtijeva oprez te u nekim slučajevima i klinički nadzor. Nedavne studije dokumentirale su interindividualnu varijabilnost u razinama DOAK-a u plazmi i odgovoru pacijenta na lijek. Iako klinički i biokemijski čimbenici mogu dovesti do interindividualnih varijabilnosti prisustvo genskih varijanti ili interakcije lijekova mogu doprinijeti tim razlikama. Potrebno je razumjeti ulogu farmakogenomike prvenstveno polimorfizam gena metaboličkih enzima i prijenosnika lijekova u interindividualnoj varijabilnosti četiri najčešće propisivana DOAK-a. Cilj istraživanja: Pregledno prikazati kako farmakogenetička predispozicija, prvenstveno polimorfizmi gena CYP3A4/5 i CES1, koji kodiraju metaboličke enzime, te ABCB1 i ABCG2, koji kodiraju transportne proteine, uz interakcije lijekova u politerapiji mogu doprinijeti interindividualnoj varijabilnost razina DOAK-a u plazmi, te učinkovitosti i sigurnosti njihove primjene. Materijali i metode: Prilikom izrade ovog rada provedena je opsežna pretraga nedavno objavljenih izvornih i preglednih znanstvenih radova, kliničkih ispitivanja, in vitro studija, terapijskih smjernica i publikacija stručnih društava. Naglasak je na polimorfizmima farmakogena bitnih za farmakokinetiku DOAK-a: gena CYP3A4/5 i CES1, za enzime uključene u biotransformaciju, te gena ABCB1 i ABCG2, za transportere lijekova i njihovom doprinosu u interindividualnoj varijabilnosti i bioraspoloživosti DOAK-a, te rizicima razvoja neželjenih učinaka prvenstveno krvarenja. Pretražena je baza podataka PubMed, Web of Science, Cochrane, Google Schoolar koristeći ključne riječi: apiksaban, CES1, CYP3A4, CYP3A5, dabigatran, direktni oralni antikoagulansi, edoksaban, farmakogenetika, farmakogenomika, genske varijante, interakcije gen-lijek, interakcije lijek-lijek, 4 krvarenje, novi oralni antikoagulansi, polimorfizam gena transportera ABCB1, ABCG2, rivaroksaban, SNP, tromboembolijski događaji u razdoblju od zadnjih 10-ak godina. Prikazani su interesantni slučajevi pacijenata iz kliničke prakse koji su zbog farmakogenetičke predispozicije i interakcije lijekova razvili nuspojave DOAK-a u vidu krvarenja. Raspravljene su prisutne dileme, te predočeno trenutno stanje u Hrvatskoj uspoređeno sa situacijom u Europi i drugdje u svijetu. Rezultati: Nekoliko varijanti gena CES1 i ABCB1 se smatra potencijalno odgovornim za nastanak interindividualnih varijabilnosti DOAK-a. Utvrđeno je da su varijante gena CES1 rs2244613 i rs8192935 povezane s nižim trough koncentracijama dabigatrana i nižim rizikom od krvarenja. S druge strane varijanta gena ABCB1 rs1045642 povezuje s povećanim vršnim koncentracijama dabigatrana i rivaroksabana, te povećanom učestalošću krvarenja. Farmakogenetička analiza varijanti gena ABCB1 rs2032582 (C.2677G> T) i rs104562 (C3435C> T) mogla bi biti opravdana i od koristi kod pacijenata na terapiji rivaroksabanom. Da bi se spriječili neželjeni učinci tijekom terapije apiksabanom kod nositelja nefunkcionalnih alela gena CYP3A5 potrebano je pažljivo odabrati dozu i pratiti nuspojave. Postoji veliki rizik od razvoja neželjenih učinaka lijeka kad se edoksaban kombinira s lijekovima koji inhibiraju CYP izoenzime u homozigotnih nositelja nefunkcionalnih alela za gen CYP3A5. Zaključak: Polimorfizam gena zajedno s istovremenom primjenom inhibitora/induktora transportnih proteina ili enzima odgovornih za metabolizam lijeka može povećati rizik od nastanka štetnih događaja vezanih uz promjenu DOAK-a. Due to good pharmacokinetics and pharmacodynamics without the requirement for routine coagulation monitoring, direct oral anticoagulants (DOAK) have seen an increase in prescribing in recent years. DOAC achieves its anticoagulant effect by direct inhibition of thrombin (dabigatran) or direct inhibition of activated factor X (rivaroxaban, apixaban and edoxaban). Although DOACs interact less with other drugs compared to warfarin, the combination of DOAC and many drugs requires caution and clinical supervision in some cases. Recent studies have documented interindividual variability in DOAC plasma levels and patient response to the drug. Although clinical and biochemical factors may lead to interindividual variability, the presence of genetic variants or drug interactions may contribute to these differences. The role of pharmacogenomics, namely polymorphism of metabolic enzyme genes and drug transporters, in the interindividual variability of the four most often prescribed DOACs, must be understood. Objectives: Demonstrate how pharmacogenetic predisposition, primarily polymorphisms of CYP3A4 / 5 metabolic enzyme genes, and CES1 and ABCB1 and ABCG2 transport proteins with drug interactions in polytherapy, may contribute to interindividual variability in DOAC plasma levels, and their efficiency and safety. Materials and methods: During the preparation of this paper, an extensive search of recently published original and reviewed scientific papers, clinical trials, in vitro studies, therapeutic guidelines and publications of professional societies was conducted. The emphasis is on pharmacogen polymorphisms that are important for DOAC pharmacokinetics: CYP3A4 / 5 and CES1 genes, for enzymes involved in biotransformation, and ABCB1 and ABCG2 genes, for drug transporters and their contribution to interindividual variability and bioavailability of DOACs, effects primarily of bleeding. The database PubMed, Web of Science, Cochrane, Google Schoolar were searched using keywords: apixaban, CES1, CYP3A4, CYP3A5, dabigatran, direct oral anticoagulants, edoxaban, pharmacogenetics, pharmacogenomics, gene variants, drug-drug interactions, gene-drug interactions, bleeding, new oral anticoagulants, polymorphism of transporter genes ABCB1, ABCG2, rivaroxaban, SNP, thromboembolic events in the period of the last 10 years. Interesting cases of patients from clinical practice who have developed DOAC side effects in the form of bleeding due to pharmacogenetic predisposition and drug interactions are presented. The present dilemmas were discussed, and the current situation in Croatia was compared to the situation in Europe and elsewhere in the world. Results: Several variants of the CES1 and ABCB1 genes are thought to be potentially responsible for the occurrence of interindividual variability in DOAC. Variants of the CES1 rs2244613 and rs8192935 genes were found to be associated with lower trough out dabigatran concentrations and a lower risk of bleeding. On the other hand, the ABCB1 gene variant rs1045642 is associated with increased peak concentrations of dabigatran and rivaroxaban, and increased bleeding frequency. Pharmacogenetic analysis of the ABCB1 gene variants rs2032582 (C.2677G>T) and rs104562 (C3435C>T) could be justified and useful in patients on rivaroxaban therapy. To prevent side effects during apixaban therapy in carriers of non-functional alleles of the CYP3A5 gene, the dose should be carefully selected and adverse reactions monitored. There is a high risk of developing adverse drug reactions when edoxaban is combined with drugs that inhibit CYP isoenzymes in homozygous carriers of non-functional alleles for the CYP3A5 gene. Conclusion: Gene polymorphism in combination with the concomitant use of inhibitors / inducers of transport proteins or enzymes responsible for drug metabolism may increase the risk of adverse events associated with alterations in DOACs.

Intestinal efflux transporters affect the gastrointestinal processing of many drugs but further data on their intestinal expression levels are required. Relative mRNA expression and relative and absolute protein expression data of transporters are commonly measured by real-time polymerase chain reaction (RT-PCR), Western blot and mass spectrometry-based targeted proteomics techniques. All of these methods, however, have their own strengths and limitations, and therefore, validation for optimized quantification methods is needed. As such, the identification of the most appropriate technique is necessary to effectively translate preclinical findings to first-in-human trials. In this study, the mRNA expression and protein levels of the efflux transporter P-glycoprotein (P-gp) in jejunal and ileal epithelia of 30 male and female human subjects, and the duodenal, jejunal, ileal and colonic tissues in 48 Wistar rats were quantified using RT-PCR, Western blot and liquid chromatography-tandem mass spectrometry (LC-MS/MS). A similar sex difference was observed in the expression of small intestinal P-gp in humans and Wistar rats where P-gp was higher in males than females with an increasing trend from the proximal to the distal parts in both species. A strong positive linear correlation was determined between the Western blot data and LC-MS/MS data in the small intestine of humans (R2 = 0.85). Conflicting results, however, were shown in rat small intestinal and colonic P-gp expression between the techniques (R2 = 0.29 and 0.05, respectively). In RT-PCR and Western blot, an internal reference protein is experimentally required; here, beta-actin was used which is innately variable along the intestinal tract. Quantification via LC-MS/MS can provide data on P-gp expression without the need for an internal reference protein and consequently, can give higher confidence on the expression levels of P-gp along the intestinal tract. Overall, these findings highlight similar trends between the species and suggest that the Wistar rat is an appropriate preclinical animal model to predict the oral drug absorption of P-gp substrates in the human small intestine.

Yue Liu,1,* Chenguang Yang,2,* Wenyuan Qi,1 Zuowei Pei,2 Wei Xue,1 Huolan Zhu,2 Min Dong,2 Ying Guo,2 Duanduan Cong,1 Fang Wang2 1Clinical Trial Center, National Center of Gerontology; Institute of Geriatric Medicine, Chinese Academy of Medical Science, Beijing Key Laboratory of Drug Clinical Risk and Personalized Medication Evaluation, Beijing Hospital, Beijing, People’s Republic of China; 2Internal Medicine-Cardiovascular Department, National Center of Gerontology; Institute of Geriatric Medicine, Chinese Academy of Medical Science, Beijing Hospital, Beijing, People’s Republic of China*These authors contributed equally to this workCorrespondence: Fang Wang Email bjh_wangfang@163.comAbstract: Dabigatran is a novel direct oral anticoagulant agent, whose plasma concentration is closely related to bleeding risk. Genetic polymorphisms can affect the level of plasma dabigatran. The purpose of this study was to understand the relationship between dabigatran-related genes and the plasma level of dabigatran in healthy Chinese subjects after taking a single oral dose. This study was performed with a single-center, single-dose, randomized, open-label, and four-period crossover trial design under both fasting and fed conditions. A total of 106 eligible healthy subjects were enrolled in the study and 104 were genotyped. One-way analysis of variance (ANOVA) was used to compare pharmacokinetic parameters among different genotypes and linear regression was applied to explore the multiplicative interaction between variables. In this study, we found that the genotype frequencies of CES1 rs2244613 and CES1 rs8192935 were significantly different between Chinese and Caucasians, but the genotype frequencies of ABCB1 rs1045642 and ABCB1 rs4148738 were similar in both populations. CES1 rs8192935 were associated with the peak concentration of dabigatran. There was no significant gender difference in the exposure level of dabigatran. Furthermore, food significantly delayed the absorption of dabigatran but had little effect on Cmax and AUC0-∞.Keywords: anticoagulants, dabigatran, genetics, pharmacogenetics, CES1, ABCB1

Dabigatran etexilate is a prodrug of dabigatran, a oral direct inhibitor of thrombin. Pharmacokinetics of dabigatran etexilate doesn’t have the disadvantages of vitamin K antagonists. However, pharmacokinetics and pharmacogenetics of dabigatran are variable. This can affect both effectiveness and safety of anticoagulant therapy. It is considered that CES1 enzyme and P-glycoprotein (CES1 and ABCB1 genes accordingly) play important role in pharmacokinetics of dabigatran etexilate. UDP-glucuronosyltransferase enzymes UGT2B15, UGT1A9, UGT2B7 (UGT2B15, UGT1A9, UGT2B7 genes accordingly) take part in the metabolism of active dabigatran. Presence of these gene’s single-nucleotide variants (SNV) can affect effectiveness and safety of dabigatran etexilate usage. The goal of this review is analysis of associated researches of SNV genes CES1 and ABCB1 and search for new candidate genes that reveal effectiveness and safety of dabigatran etexilate usage.Materials and methods. The search for full-text publications in Russian and English languages containing key words “dabigatran etexilate”, “dabigatran”, “pharmacokinetics”, “effectiveness”, “safety” was carried out amongst literature of the past twenty years with the use of eLibrary, PubMed, Web of Science, OMIM data bases. Pharmacokinetics and pharmacogenetics of dabigatran etexilate are considered in this review. The hypothesis about UDP-glucuronosyltransferase enzymes influence on dabigatran metabolism was examined. Nowadays more than 2000 SNV CES1 and ABCB1 genes are identified, but their potential influence on pharmacokinetics of dabigatran etexilate and its active metabolite (dabigatran) in clinical practice needs to be further researched. Role of SNV UDP-glucuronosyltransferase genes (UGT2B15, UGT1A9, UGT2B7) in dabigatran’s effectiveness and safety is not explored enough. However, UGT2B15 gene can be a potential candidate gene for research on safety of this drug.

P-glycoprotein (P-gp) has been implicated in lung cancer development, disease progression, and patient survival. Changes in the ABCB1 expression level may correlate with tumorigenesis and the formation of multidrug resistance (MDR). In addition, epigenetic modifications such as DNA methylation are involved in the regulation of the transcriptional activity of this gene. Therefore, we focused on an analysis of changes in the expression of ABCB1 and its methylation, taking into account their potential associations with the clinicopathological parameters of LUAD and LUSC. The TNMplot, UALCAN, cBioPortal, PrognoScan, and MEXPRESS databases were used to investigate the role of this gene in lung cancer progression. ABCB1 expression in lung tissue was significantly downregulated in cancer cells, but differences also resulted from age, gender, ethnicity, and smoking cessation. Moreover, decreased levels of gene transcript were associated with both a higher stage of cancer and a lower probability of survival. It is worth emphasizing that the presence/direction of ABCB1 expression changes are frequently unique to specific histological tumor subtypes. Finally, it is equally important that the main methylation promoter is one of the causes of decreased gene expression in lung cancer cells. Taken together, these data establish the ABCB1 transporter gene as an important prognostic factor that could alter disease progression and contribute to the survival of cancer patients.

Acquired chemoresistance during chemotherapy, often accompanied by cross- and multi-resistance, limits therapeutic outcomes and leads to recurrence. In order to create in vitro model systems to understand acquired doxorubicin-resistance, we generated doxorubicin-resistant sublines of canine prostate adenocarcinoma and urothelial cell carcinoma cell lines. Chemoresistance to doxorubicin, cross-resistance to carboplatin, and the reversibility of the acquired resistance by the specific MDR1-inhibitor tariquidar were quantified in metabolic assays. Resistance mechanisms were characterized by expression of the efflux transporters MDR1 and RALBP1, as well as the molecular target of doxorubicin, TOP2A, with qPCR and Western blotting. Six out of nine cell lines established stable resistance to 2 µM doxorubicin. Drug efflux via massive MDR1 overexpression was identified as common, driving resistance mechanism in all sublines. MDR1 inhibition with tariquidar extensively reduced or reversed the acquired, and also partly the parental resistance. Three cell lines developed additional, non-MDR1-dependent resistance. RALBP1 was upregulated in one resistant subline at the protein level, while TOP2A expression was not altered. Combination therapies aiming to inhibit MDR1 activity can now be screened for synergistic effects using our resistant sublines. Nevertheless, detailed resistance mechanisms and maintained molecular target expression in the resistant sublines are still to be examined.

Neuroinflammation and brain lipid imbalances are observed in Alzheimer’s disease (AD). Tumor necrosis factor-α (TNFα) and the liver X receptor (LXR) signaling pathways are involved in both processes. However, limited information is currently available regarding their relationships in human brain pericytes (HBP) of the neurovascular unit. In cultivated HBP, TNFα activates the LXR pathway and increases the expression of one of its target genes, the transporter ATP-binding cassette family A member 1 (ABCA1), while ABCG1 is not expressed. Apolipoprotein E (APOE) synthesis and release are diminished. The cholesterol efflux is promoted, but is not inhibited, when ABCA1 or LXR are blocked. Moreover, as for TNFα, direct LXR activation by the agonist (T0901317) increases ABCA1 expression and the associated cholesterol efflux. However, this process is abolished when LXR/ABCA1 are both inhibited. Neither the other ABC transporters nor the SR-BI are involved in this TNFα-mediated lipid efflux regulation. We also report that inflammation increases ABCB1 expression and function. In conclusion, our data suggest that inflammation increases HBP protection against xenobiotics and triggers an LXR/ABCA1 independent cholesterol release. Understanding the molecular mechanisms regulating this efflux at the level of the neurovascular unit remains fundamental to the characterization of links between neuroinflammation, cholesterol and HBP function in neurodegenerative disorders.

Clopidogrel is an antiplatelet drug that displays significant interindividual variability in treatment response. Its bioavailability depends on the function of P-glycoprotein (P-gp), which is coded by a highly polymorphic ABCB1 gene. Thus, the aim of this study was to investigate the effect of ABCB1 genetic polymorphism on clopidogrel efficacy and safety and to determine the frequency distribution of its most common single nucleotide polymorphisms (SNPs) in 106 Montenegrin cardiology patients. Clopidogrel efficacy and safety were followed up during 1 year after hospitalization, with the lack of efficacy and adverse drug reactions observed in 11 (10.4%) and 8 patients (7.5%), respectively. Genotyping for ABCB1 SNPs rs1128503 (1236C > T), rs2032582 (2677G > A/T), and rs1045642 (3435C > T) was performed by the real-time PCR method, and the variant alleles were detected with the frequencies of 42.9, 44.8, and 52.8%, respectively. No significant association was observed between any of the examined genotypes and clopidogrel efficacy (p = 0.253) or safety (p = 0.424). Due to small sample size, co-treatment with other drugs, and other genetic factors not taken into account, we believe the absence of correlation between ABCB1 genotypes and indicators of clopidogrel efficacy and safety in this study should be apprehended conditionally, and that larger and better-controlled studies are warranted.

Modified FOLFIRINOX (mFOLFIRINOX) and gemcitabine + nab-paclitaxel (GemNab) regimens represent a standard treatment in advanced pancreatic cancer (aPC). DPYD and UGT1A1 variants are relevant predictors of fluoropyrimidine and irinotecan-associated adverse events (AEs). Furthermore, data about the associations between polymorphisms in ABCB and CDA genes and GemNab-related toxicities are still controversial. The present study analyzes the association between DPYD, UGT, ABCB1, CDA variants, and AEs in aPC patients (pts) treated with mFOLFIRINOX or GemNab. Blood samples collected from 104 aPC pts treated with mFOLFIRINOX and 63 with GemNab were tested for DPYD c.1679T>G, IVS14+1G>A, c.2194G>A, c.2846A>T, UGT1A1*28, CDA c.79A>C, and ABCB1 c.1236C>T, c.2677G>T/A, c.3435C>T by real-time PCR and automatic sequencing. In mFOLFIRINOX cohort, DPYD IVS14+1GA genotype was associated with G4 hematological AEs, while the UGT1A1*28 significantly correlated with the risk of thrombocytopenia (p = 0.006). In the GemNab cohort, a significant association between CDA c.79CC and high-grade nausea was observed (p = 0.002). Moreover, the presence of at least a mutant allele in ABCB1 increased the risk of overall hematological AEs (p = 0.01), both further strengthened by the presence of CDA c.79CC (p = 0.0002). DPYD IVS14+1A allele is confirmed to be associated with fluoropyrimidine life-threatening toxicities, and UGT1A1*28 is related with a higher risk of hematologic AEs following irinotecan treatment. CDA c.79C and ABCB1 c.1236T, c.2677T/A, and c.3435T mutant alleles are predictive biomarkers of GemNab-related AEs. All these variants should be considered in aPC pts candidate to mFOLFIRINOX or GemNab treatments.

Objective Genetic polymorphisms can influence the chemotherapeutic response; however, previous studies have produced conflicting results, and have failed to identify the most relevant polymorphisms for predicting the response to treatment in patients with cancer. The present meta-analysis was conducted to determine the correlation between two polymorphisms (rs1045642 and rs1128503) in ATP-binding cassette transporter B subfamily member 1 (ABCB1), which is associated with multidrug resistance, and the survival of patients treated with taxane-containing chemotherapy. Methods Several databases, including PubMed and Embase, were used to retrieve articles evaluating the association between the ABCB1 rs1045642 and rs1128503 polymorphisms and survival, published prior to August 2019. The meta-analysis was conducted using R software to determine the pooled hazard ratio (HR) and 95% confidence intervals (95% CIs). Results Fifteen studies involving 3320 patients were included in the meta-analysis. The effect of the rs1128503 polymorphism on progression-free survival remained significant in the heterozygote (HR 0.81; 95% CI: 0.67-0.98) and homozygote (HR 0.71; 95% CI: 0.58-0.88) models. The TT genotype rs1128503 was associated with better overall survival (HR 0.72; 95% CI: 0.53-0.97). Conclusion Carriers of the rs1128503 T allele of ABCB1 showed a survival benefit after taxane-containing chemotherapy.

Background . Mirtazapine is used to treat patients with depressive disorders. A large proportion of patients in this group do not adequately respond to mirtazapine therapy, while many develop undesirable drug reactions of type A. According to the previous studies, P-gp is involved in the biotransformation of mirtazapine, the activity of which is highly dependent on the polymorphism of the gene encoding it. Aim. The aim of our study was to study the effect of mirtazapine gene polymorphism on the efficacy and safety of mirtazapine therapy in patients with depressive disorders, comorbid with alcohol dependence. Materials and methods . The study included 119 male patients with depressive disorders, comorbid with alcohol dependence (age 38.7 ± 16.0 years). As a therapy, mirtazapine was used at a dose of 37.8 ± 13.8 mg / day. Evaluation of the effectiveness profile was carried out using psychometric scales. The safety profile was evaluated using the UKU Side-Effect Rating Scale. Genotyping was carried out by polymerase chain reaction in real time. Results . In the course of the study, results statistically significant in terms of evaluating efficacy and safety were not obtained (HAMD scores at the end of the course of therapy: (CC) 2.5 [2.0; 4.0], (CT) 2.0 [ 1.0; 3.0] and (TT) 2.0 [1.0; 3.0], p > 0.999; according to the UKU scale: (CC) 3.0 [2.8; 3.0], ( CT) 3.0 [3.0; 3.0] and (TT) 3.0 [3.0; 3.0], p > 0.999). Conclusion . The study of 119 patients with depressive disorders comorbid with alcohol dependence showed that 3435C> T polymorphism of the ABCB1 gene (rs1045642) does not affect the clinical efficacy and safety of mirtazapine.

Many intensive studies are devoted to identifying novel cancer diagnostics or therapy strategies that would boost cancer therapy efficacy and recovery rates. Importantly, polymorphisms in the genes coding for ABC family proteins were considered good candidates for cancer development risk or cancer drug resistance markers. For this reason, we decided to assess the contribution of ABCB1’s most common variants (i.e., G2677T/A in exon 21/rs2032582 and C3435T in exon 26/rs1045642) to the cancer therapy response in breast cancer patients. A 10-year follow-up analysis of 157 breast cancer patients was performed. Clinical assessment, ABCB1 polymorphism status, estrogen/progesterone/human epidermal receptors status, and other characteristics were compared according to the follow-up status using the Chi-square statistic. For the analysis of overall survival curves in TCGA breast cancer patients, the Xena browser was used. We show that neither 2677 nor 3435 polymorphisms contributed to the survival of breast cancer patients. Interestingly, but not surprisingly, estrogen and progesterone receptors status were good prognostic factors and positively correlated with a disease-free survival for up to 10 years. To summarize, ABCB1 polymorphisms status may be one of the numerous factors that affect cancer development. However, they may not be the critical ones when it comes to risk or recovery assessment. Consequently, they may not be treated as reliable prognostic or predictive markers in breast cancer patients’ evaluation, which supports the previous findings and current knowledge.

Sotorasib (Lumakras™) is the first FDA-approved KRASG12C inhibitor for treatment of patients with non-small cell lung cancer (NSCLC) carrying this mutation. Using genetically modified mouse models, we studied the influence of the efflux transporters ABCB1 and ABCG2, the OATP1a/1b uptake transporters, and the CYP3A drug-metabolizing enzyme complex on the plasma pharmacokinetics and tissue distribution of oral sotorasib. In vitro, sotorasib was a potent substrate for human ABCB1 and a modest substrate for mouse Abcg2, but not for human ABCG2. In vivo, the brain-to-plasma ratio of sotorasib (40 mg/kg) was highly increased in Abcb1a/1b-/- (5.9-fold) and Abcb1a/1b;Abcg2-/- (7.6-fold) compared to wild-type mice, but not in single Abcg2-/- mice. Upon coadministering elacridar, an ABCB1/ABCG2 inhibitor, sotorasib brain accumulation increased 7.5-fold, approaching the levels observed in Abcb1a/1b-deficient mice. No acute CNS toxicity emerged upon boosting of the sotorasib exposure. In Oatp1a/1b-deficient mice, we observed a 2-fold reduction in liver disposition compared to wild-type mice, although these uptake transporters had no noticeable impact on sotorasib plasma exposure. However, plasma exposure was limited by mouse Cyp3a and human CYP3A4, as the AUC0–4 h in Cyp3a-/- mice was increased by 2.5-fold compared to wild-type mice, and subsequently strongly decreased (by 3.9-fold) in Cyp3aXAV mice transgenically overexpressing human CYP3A4 in liver and intestine. Collectively, the oral availability of sotorasib was markedly limited by CYP3A and possibly also by ABCB1 and OATP1a/b, whereas its brain accumulation was strongly restricted by ABCB1. The obtained results may help to further optimize the safety and efficacy of sotorasib in clinical use.

The P-glycoprotein (P-gp/ABCB1) is responsible for a xenobiotic efflux pump that shackles intracellular drug accumulation. Additionally, it is included in the dud of considerable antiviral and anticancer chemotherapies because of the multidrug resistance (MDR) phenomenon. In the search for prospective anticancer drugs that inhibit the ABCB1 transporter, the Natural Product Activity and Species Source (NPASS) database, containing >35,000 molecules, was explored for identifying ABCB1 inhibitors. The performance of AutoDock4.2.6 software to anticipate ABCB1 docking score and pose was first assessed according to available experimental data. The docking scores of the NPASS molecules were predicted against the ABCB1 transporter. Molecular dynamics (MD) simulations were conducted for molecules with docking scores lower than taxol, a reference inhibitor, pursued by molecular mechanics-generalized Born surface area (MM-GBSA) binding energy estimations. On the basis of MM-GBSA calculations, five compounds revealed promising binding affinities as ABCB1 inhibitors with ΔGbinding < −105.0 kcal/mol. The binding affinity and stability of the identified inhibitors were compared to the chemotherapeutic agent. Structural and energetical analyses unveiled great steadiness of the investigated inhibitors within the ABCB1 active site throughout 100 ns MD simulations. Conclusively, these findings point out that NPC104372, NPC475164, NPC2313, NPC197736, and NPC477344 hold guarantees as potential ABCB1 drug candidates and warrant further in vitro/in vivo tests.

ABCB1 detoxifies cells by exporting diverse xenobiotic compounds, thereby limiting drug disposition and contributing to multidrug resistance in cancer cells. Multiple small-molecule inhibitors and inhibitory antibodies have been developed for therapeutic applications, but the structural basis of their activity is insufficiently understood. We determined cryo-EM structures of nanodisc-reconstituted, human ABCB1 in complex with the Fab fragment of the inhibitory, monoclonal antibody MRK16 and bound to a substrate (the antitumor drug vincristine) or to the potent inhibitors elacridar, tariquidar, or zosuquidar. We found that inhibitors bound in pairs, with one molecule lodged in the central drug-binding pocket and a second extending into a phenylalanine-rich cavity that we termed the “access tunnel.” This finding explains how inhibitors can act as substrates at low concentration, but interfere with the early steps of the peristaltic extrusion mechanism at higher concentration. Our structural data will also help the development of more potent and selective ABCB1 inhibitors. © 2020 National Academy of Sciences. ISSN:0027-8424 ISSN:1091-6490

Sitafloxacin, a new fluoroquinolone, has strong antibacterial activity. We evaluated the effects of sitafloxacin granules in single‐dose and multidose cohorts and the effects of ABCB1, UGT1A1, and UGT1A9 genetic polymorphisms on the pharmacokinetics (PK) of sitafloxacin in healthy subjects. The single‐dose study included 3 fasted cohorts receiving 50, 100, and 200 mg of sitafloxacin granules and 1 cohort receiving 50 mg of sitafloxacin granules with a high‐fat meal. The multidose study included 1 cohort receiving 100 mg of sitafloxacin granules once daily for 5 days. PK parameters were calculated using noncompartmental parameters based on concentration‐time data. The genotypes for ABCB1, UGT1A1, and UGT1A9 single‐nucleotide polymorphisms were determined using Sanger sequencing. Subsequently, the association between sitafloxacin PK parameters and target single‐nucleotide polymorphisms was analyzed. Sitafloxacin granules were well tolerated up to 200 and 100 mg in the single‐dose and multidose studies, respectively. Sitafloxacin AUC and Cmax increased linearly within the detection range, and a steady state was reached within 3 days after the administration of multiple oral doses. Our findings showed that Cmax was lower in the ABCB1 (rs1045642) mutation group, whereas t1/2 was longer in the UGT1A1 (rs2741049) and UGT1A9 (rs3832043) mutation groups. In conclusion, sitafloxacin granules were safe at single doses and multiple doses up to 200 and 100 mg/day, respectively, with a linear plasma PK profile. However, ABCB1 (rs1045642), UGT1A1 (rs2741049), and UGT1A9 (rs3832043) genetic polymorphisms are likely to influence the Cmax or t1/2 and thereby merit further clinical evaluation.

Tolvaptan efficacy for heart failure has a large interindividual variation. This study aimed to evaluate the influence of CYP3A5 and ABCB1 genotypes on tolvaptan pharmacokinetics and their relationships with plasma markers of CYP3A activity and laboratory test values in heart failure patients. Fifty-eight heart failure patients receiving oral tolvaptan for volume overload were enrolled. Blood samples for determination of pre-dose plasma concentrations of tolvaptan and its metabolites were collected. CYP3A5 and ABCB1 genotypes, plasma 4β-hydroxycholesterol/total cholesterol ratio (4β-OHC/TC) and 25-hydroxyvitamin D (25-OHD), and serum laboratory test values were evaluated. The CYP3A5*3/*3 genotype was associated with a higher plasma concentration of tolvaptan but not with its metabolic ratios. The ABCB1 3435C > T, 2677G > T/A and 1236C > T polymorphisms affected neither tolvaptan pharmacokinetics nor its metabolism. Plasma 4β-OHC/TC and 25-OHD concentration were not correlated with plasma tolvaptan concentration. In a stratified analysis based on CYP3A5 genotype, plasma 4β-OHC/TC had a negative correlation with plasma tolvaptan concentration in the patients with the CYP3A5*1 allele, while the plasma concentration of 25-OHD did not. The CYP3A5*3/*3 genotype was associated with a higher serum sodium level in the patients with volume overload. The plasma concentration of 25-OHD had a positive correlation with the serum total bilirubin level. In conclusion, CYP3A5*3 but not ABCB1 genotypes elevated tolvaptan plasma exposure in heart failure patients. CYP3A5-deficient patients treated with tolvaptan had a higher serum sodium level. The CYP3A5 genotype altered the relationship between plasma tolvaptan and 4β-OHC.