A phase 1b study of OXIRI in pancreatic adenocarcinoma patients and its immunomodulatory effects.

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal and debilitating disease with limited therapeutic options. The aim of this clinical study was to evaluate the safety, efficacy and pharmacokinetics of a novel regimen comprised of metronomic oxaliplatin (O), chronomodulated capecitabine (X) and UGT1A1 genotype-guided dosing of irinotecan (IRI) [OXIRI] as well as its immunomodulatory effects. Thirty-six patients were enrolled into either dose-escalation or expansion cohorts. In the dose escalation phase, capecitabine doses (2000, 2650, 3500 and 4500 mg/day) were administered at midnight on days 1 to 14 while oxaliplatin and irinotecan were intravenously infused at fixed doses of 50 and 75 mg/m2 respectively on days 1, 8 in a 21-day cycle. The maximum tolerated dose of capecitabine was 2650 mg/day and the most common grade 3 adverse events were neutropenia (30.6%) and diarrhea (13.9%). No grade 4 toxicity was observed. UGT1A1-genotype directed dosing resulted in similar exposure levels of irinotecan, SN-38 and SN-38G in all patients. Objective response rate was 22.2%. Median overall survival and progression-free survival were 8.1 and 5.2 months, respectively. Exploratory immunoprofiling by flow cytometry and quantitative spatial localization analysis of infiltrated immune cells performed on biopsy and plasma samples revealed significant declines in CCL22, CCL2 and TNFα levels at end of first cycle and an active host immune response. Our study showed that OXIRI was well-tolerated and exhibited good efficacy, with immunomodulatory effects. It may be considered as an alternative to FOLFIRINOX in patients intolerant to the latter.

Pharmacokinetics of oral versus intravenous ibuprofen for closure of patent ductus arteriosus: A pilot randomised controlled study.

AIM: This pilot study aimed to compare the pharmacokinetic profiles of oral (PO) and intravenous (IV) ibuprofen for treatment of patent ductus arteriosus (PDA) in preterm neonates. METHODS: In a single-centre, parallel, randomised open-label trial, neonates ≤35 weeks, weight <1800 g with haemodynamically significant PDA during the first week of life were recruited between June 2017 and February 2019 and randomised to receive either PO or IV ibuprofen at standard dosage of 10, 5 and 5 mg/kg every 24 h for three consecutive days. Plasma concentrations of ibuprofen were quantified using a validated high-performance liquid chromatography method and pharmacokinetic parameters were calculated. Treatment outcomes were recorded. RESULTS: Eleven neonates participated in the trial, six and five patients receiving PO and IV ibuprofen, respectively. Pharmacokinetic analysis reveals similar ibuprofen exposure levels in treatment groups. Median dose- and weight-normalised Cmax values of PO and IV groups were 2.12 and 2.53 g/mL respectively (P = 0.082) and median AUC0-24 levels were comparable (PO: 34.6 g*h/mL vs. IV: 50.7.6 g*h/mL, P = 0.25). CONCLUSION: This exploratory study demonstrates comparable pharmacokinetics of PO and IV formulations of ibuprofen in preterm neonates. Larger prospective studies are required to validate these findings.

An intronic FTO variant rs16952570 confers protection against thiopurine-induced myelotoxicities in multiethnic Asian IBD patients.

Thiopurines are used in the treatment of inflammatory bowel disease (IBD) but remain clinically challenging to manage due to wide interpatient variability in clinical outcomes and adverse events. Apart from genetic variants in thiopurine S-methyltransferase (TPMT) and nudix hydrolase 15 (NUDT15) genes, polymorphisms in FTO alpha-ketoglutarate dependent dioxygenase (FTO) were found predictive of thiopurine-induced leukopenia, albeit with conflicting results. To clarify the role of FTO variants in a multiethnic Asian IBD cohort, we recruited 149 patients on thiopurine-based therapy and genotyped two FTO variants p.Ala134Thr (rs79206939) and rs16952570 T > C using Sanger sequencing. FTO p.Ala134Thr (rs79206939) was non-polymorphic and absent whereas intronic rs16952570 T > C was equally prevalent in Chinese (22%) and Indians (18%) and higher in Malays (28%). Higher nadir white blood cell (WBC) and absolute neutrophil count (ANC) levels were observed in patients harboring FTO rs16952570 CC genotypes compared with TT carriers at 4, 8, and 12 weeks after start of thiopurine therapy (P < 0.05). A similar trend was observed in patients carrying the previously well-characterized NUDT15 rs116855232 wild-type CC genotypes. Further in silico analysis suggests that FTO variants linked to rs16952570, particularly rs74018601, may play a regulatory role in altering the FTO expression. The findings from this study indicate a novel protective association with the FTO variant rs16952570 CC genotype and hematological parameters.

Influence of the KDM4A rs586339 polymorphism on overall survival in Asian non-small-cell lung cancer patients.

The critical role of lysine demethylase 4A (KDM4A), in regulating chromatin structure and consequently in driving cellular proliferation and oncogenesis has been the focus of recent studies. Non-small-cell lung cancer (NSCLC) patients with adenocarcinoma histology who were homozygous for KDM4A single nucleotide polymorphism (SNP)-A482 (rs586339) were recently shown to have significantly worse overall survival (OS) compared with patients with the wild-type or the heterozygous genotype at this locus (hazard ratio=1.68, P=0.042). In the current study, we investigated the association between the same polymorphism with OS in our Asian NSCLC-adenocarcinoma patients comprising Chinese (N=572), Malays (N=50), and Indians (N=22). KDM4A SNP-A482 genotype status was determined by Sanger sequencing. OS was calculated from the date of diagnosis to date of death or censored at the date of last follow-up. Kaplan-Meier analysis, log-rank test, and Cox regression methods were utilized to evaluate OS outcomes. KDM4A SNP-A482 had a minor allele (C) frequency of 18.8% and a major allele (A) frequency of 81.2% in our Asian NSCLC (adenocarcinoma) patients. However, the OS in our Asian NSCLC patients homozygous for KDM4A SNP-A482 was not significantly different from those who were wild type or heterozygous at this locus [CC vs. AA/AC: median OS (95% confidence interval): 40.2 (18.7-61.6) vs. 29.6 (26.9-32.3) months; P=0.858]. The results remained statistically nonsignificant even after adjustment for epidermal growth factor receptor mutational status, suggesting that KDM4A SNP-A482 does not significantly influence OS in Asian NSCLC patients.

Genetic risk of extranodal natural killer T-cell lymphoma: a genome-wide association study.

BACKGROUND: Extranodal natural killer T-cell lymphoma (NKTCL), nasal type, is a rare and aggressive malignancy that occurs predominantly in Asian and Latin American populations. Although Epstein-Barr virus infection is a known risk factor, other risk factors and the pathogenesis of NKTCL are not well understood. We aimed to identify common genetic variants affecting individual risk of NKTCL. METHODS: We did a genome-wide association study of 189 patients with extranodal NKTCL, nasal type (WHO classification criteria; cases) and 957 controls from Guangdong province, southern China. We validated our findings in four independent case-control series, including 75 cases from Guangdong province and 296 controls from Hong Kong, 65 cases and 983 controls from Guangdong province, 125 cases and 1110 controls from Beijing (northern China), and 60 cases and 2476 controls from Singapore. We used imputation and conditional logistic regression analyses to fine-map the associations. We also did a meta-analysis of the replication series and of the entire dataset. FINDINGS: Associations exceeding the genome-wide significance threshold (p<5 × 10(-8)) were seen at 51 single-nucleotide polymorphisms (SNPs) mapping to the class II MHC region on chromosome 6, with rs9277378 (located in HLA-DPB1) having the strongest association with NKTCL susceptibility (p=4·21 × 10(-19), odds ratio [OR] 1·84 [95% CI 1·61-2·11] in meta-analysis of entire dataset). Imputation-based fine-mapping across the class II MHC region suggests that four aminoacid residues (Gly84-Gly85-Pro86-Met87) in near-complete linkage disequilibrium at the edge of the peptide-binding groove of HLA-DPB1 could account for most of the association between the rs9277378*A risk allele and NKTCL susceptibility (OR 2·38, p value for haplotype 2·32 × 10(-14)). This association is distinct from MHC associations with Epstein-Barr virus infection. INTERPRETATION: To our knowledge, this is the first time that a genetic variant conferring an NKTCL risk is noted at genome-wide significance. This finding underlines the importance of HLA-DP antigen presentation in the pathogenesis of NKTCL. FUNDING: Top-Notch Young Talents Program of China, Special Support Program of Guangdong, Specialized Research Fund for the Doctoral Program of Higher Education (20110171120099), Program for New Century Excellent Talents in University (NCET-11-0529), National Medical Research Council of Singapore (TCR12DEC005), Tanoto Foundation Professorship in Medical Oncology, New Century Foundation Limited, Ling Foundation, Singapore National Cancer Centre Research Fund, and the US National Institutes of Health (1R01AR062886, 5U01GM092691-04, and 1R01AR063759-01A1).

Pharmacogenetics of irinotecan, doxorubicin and docetaxel transporters in Asian and Caucasian cancer patients: a comparative review.

Drug efflux and influx transporters play critical roles in regulating the cellular drug disposition and modulating the pharmacokinetics and pharmacodynamics of anti-cancer agents, which may potentially alter treatment outcomes. The efficiency of drug transport is often dependent on the expression and activity of these membrane-bound proteins, factors which have been shown to be regulated by genes that are known to be highly polymorphic in different ethnic populations. The role of drug transporters becomes even more critical for anti-cancer agents due to the narrow therapeutic windows that separate treatment response and toxicities for these agents. Moreover, high inter-individual variability in the disposition of anti-cancer agents often results in variable treatment outcomes among patients receiving standard doses of the same drug. Such variability has been attributed at least in part to polymorphisms in genes encoding drug-metabolizing enzymes and transporter. To date, numerous pharmacogenetic studies have investigated the associations between variants in the ABC and SLC transporters genes with drug disposition, treatment outcomes and drug-induced toxicities. However, the strengths of these associations and their clinical relevance in different ethnic populations have not been critically examined. This review aims to summarize and evaluate the implications of pharmacogenetic variants in the ABC and SLC transporters genes on the pharmacokinetics and clinical outcomes of three anti-cancer agents: irinotecan, docetaxel and doxorubicin in Caucasian and Asian patients.

Association of CYP2C19*2 and associated haplotypes with lower norendoxifen concentrations in tamoxifen-treated Asian breast cancer patients.

AIM: The aim was to examine the influence of CYP2C19 variants and associated haplotypes on the disposition of tamoxifen and its metabolites, particularly norendoxifen (NorEND), in Asian patients with breast cancer. METHODS: Sixty-six CYP2C19 polymorphisms were identified in healthy Asians (n = 240), of which 14 were found to be tightly linked with CYP2C19*2, CYP2C19*3 and CYP2C19*17. These 17 SNPs were further genotyped in Asian breast cancer patients receiving tamoxifen (n = 201). Steady-state concentrations of tamoxifen and its metabolites were quantified using liquid chromatography­mass spectrometry. Non-parametric tests and regression methods were implemented to evaluate genotypic­phenotypic associations and haplotypic effects of the SNPs. RESULTS: CYP2C19 functional polymorphisms and their linked SNPs were not significantly associated with plasma concentrations of tamoxifen and its main metabolites N-desmethyltamoxifen, (Z)-4-hydroxytamoxifen and (Z)-Endoxifen. However, CYP2C19*2 and its seven linked SNPs were significantly associated with lower NorEND concentrations, MRNorEND/NDDM and MRNorEND/(Z)-END. Specifically, patients carrying the CYP2C19*2 variant allele A had significantly lower NorEND concentrations [median (range), GG vs. GA vs. AA: 1.51 (0.38­3.28) vs. 1.28 (0.30­3.36) vs. 1.15 ng ml−1 (0.26­2.45, P = 0.010)] as well as significantly lower MRNorEND/(Z)-END [GG vs. GA vs. AA: 9.40 (3.27­28.35) vs. 8.15 (2.67­18.9) vs. 6.06 (4.47­14.6), P < 0.0001] and MRNorEND/NDDM [GG vs. GA vs. AA: 2.75 (0.62­6.26) vs. 2.43 (0.96­4.18) vs. 1.75 (1.10­2.49), P < 0.00001]. CYP2C19 H2 haplotype, which included CYP2C19*2, was also significantly associated with lower NorEND concentrations (P = 0.0020), MRNorEND/NDDM (P < 0.0001) and MRNorEND/(Z)-END (P < 0.0001), indicating significantly lower formation rates of NorEND. CONCLUSION: These data highlight the potential relevance of CYP2C19 pharmacogenetics in influencing NorEND concentrations in tamoxifen-treated patients, which may influence treatment outcomes.

Pharmacogenetic effects of regulatory nuclear receptors (PXR, CAR, RXRα and HNF4α) on docetaxel disposition in Chinese nasopharyngeal cancer patients.

PURPOSE: This exploratory study was aimed at elucidating the pharmacogenetics of regulatory nuclear receptors (PXR, CAR, RXRα and HNF4α) and their implications on docetaxel pharmacokinetics and pharmacodynamics in local Chinese nasopharyngeal cancer patients. METHODS: A total of 59 single nucleotide polymorphisms (SNPs), including tag-SNPs and functionally relevant SNPs of the genes encoding these regulatory nuclear receptors (PXR/NR1I2, CAR/NR1I3, RXRα/NR2B1 and HNF4α/NR2A1), were profiled in the patients enrolled in our study by direct sequencing (N = 50). The generalized linear model was employed to estimate the haplotypic effects on the pharmacokinetics and pharmacodynamics of the patients. RESULTS: The pharmacokinetic profiles of docetaxel in these patients were characterized by marked interindividual variability, with approximately four- to sixfold variations observed in Cmax, AUC0-∞ and CL. Individual SNP association tests revealed that polymorphisms in NR2B1 and NR2A1 were significantly correlated with altered docetaxel pharmacokinetics. Subsequent haplotype association analysis identified the NR2B1 LD block 2 AG haplotype [*+4458G>A(rs3132291) and *+4988A>G(rs4842198)] to be significantly associated with altered pharmacokinetics, in which patients carrying two copies of the AG haplotype had approximately a 20 % decreased Cmax and AUC0-∞ and a 21 % increased CL compared to those who carried only one copy or no copies of the haplotype. A number of SNPs in NR1I2, NR1I3, NR2B1 and NR2A1 were also associated with a significant decrease in blood counts from baseline. No haplotype was found to exert any effects on the pharmacodynamics parameters. CONCLUSIONS: The present exploratory study identified several SNPs in the genes encoding regulatory nuclear receptors which may account for the interpatient variability in docetaxel pharmacokinetics and pharmacodynamics. These findings highlight the important role of regulatory nuclear receptors on the disposition of docetaxel.

Automated warfarin dose prediction for Asian, American, and Caucasian populations using a deep neural network.

Existing warfarin dose prediction algorithms based on pharmacogenetics and clinical parameters have not been used clinically due to the absence of external validation, lack of assessment for clinical utility, and high risk of bias. Moreover, given the high degree of heterogeneity across different datasets used to develop these algorithms, it is unsurprising that prediction errors remain high, and dosing accuracy is dependent on specific ethnic populations. To circumvent these challenges, deep neural models are increasingly used to improve the precision and accuracy of warfarin dose predictions. Hence, this study sought to develop a deep learning-based model using a well-established curated dataset of over 6000 patients from the International Warfarin Pharmacogenomics Consortium (IWPC). Clinically-relevant input data such as physical attributes, medical conditions, concomitant medications, genotype status of functional warfarin genetic polymorphisms, and therapeutic INR were entered followed by applying a unique and robust training and validation method. The deep model yielded a low average mean absolute error (MAE) of 7.6 mg/week and a relatively low mean percentage of error of 40.9% in Asians, 14.2 mg/week MAE and 36.9% in African Americans, and 12.7 mg/week MAE and 45.4% mean percentage of error in White Caucasians. This model also resulted in 36.4% of all patients with a predicted dose within 20% of the administered dose. Hence, our proposed deep model provides an alternative to predicting warfarin dose in the clinical setting upon validation in ethnically-similar datasets.

Cross-Ancestry Genome-Wide Association Study Defines the Extended CYP2D6 Locus as the Principal Genetic Determinant of Endoxifen Plasma Concentrations.

The therapeutic efficacy of tamoxifen is predominantly mediated by its active metabolites 4-hydroxy-tamoxifen and endoxifen, whose formation is catalyzed by the polymorphic cytochrome P450 2D6 (CYP2D6). Yet, known CYP2D6 polymorphisms only partially determine metabolite concentrations in vivo. We performed the first cross-ancestry genome-wide association study with well-characterized patients of European, Middle-Eastern, and Asian descent (n = 497) to identify genetic factors impacting active and parent metabolite formation. Genome-wide significant variants were functionally evaluated in an independent liver cohort (n = 149) and in silico. Metabolite prediction models were validated in two independent European breast cancer cohorts (n = 287, n = 189). Within a single 1-megabase (Mb) region of chromosome 22q13 encompassing the CYP2D6 gene, 589 variants were significantly associated with tamoxifen metabolite concentrations, particularly endoxifen and metabolic ratio (MR) endoxifen/N-desmethyltamoxifen (minimal P = 5.4E-35 and 2.5E-65, respectively). Previously suggested other loci were not confirmed. Functional analyses revealed 66% of associated, mostly intergenic variants to be significantly correlated with hepatic CYP2D6 activity or expression (ρ = 0.35 to -0.52), and six hotspot regions in the extended 22q13 locus impacting gene regulatory function. Machine learning models based on hotspot variants (n = 12) plus CYP2D6 activity score (AS) increased the explained variability (~ 9%) compared with AS alone, explaining up to 49% (median R2 ) and 72% of the variability in endoxifen and MR endoxifen/N-desmethyltamoxifen, respectively. Our findings suggest that the extended CYP2D6 locus at 22q13 is the principal genetic determinant of endoxifen plasma concentration. Long-distance haplotypes connecting CYP2D6 with adjacent regulatory sites and nongenetic factors may account for the unexplained portion of variability.

Influence of SLCO1B3 haplotype-tag SNPs on docetaxel disposition in Chinese nasopharyngeal cancer patients.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: SLCO1B3 is an influx transporter located at the hepatocyte basolateral membrane and it is involved in the uptake of a broad range of drug substrates including docetaxel. The pharmacogenetics of SLCO1B3 is not well characterized and previous in vivo and in vitro studies reported conflicting results with regards to the functional effects of the limited number of SLCO1B3 polymorphisms that were studied. Docetaxel displays a wide interindividual variability in its pharmacokinetics and pharmacodynamics and an understanding of SLCO1B3 pharmacogenetics might provide clinical benefits in guiding docetaxel dosing. WHAT THIS STUDY ADDS: The SLCO1B3 gene was comprehensively screened in the local healthy Asian populations (n= 168). A strong linkage disequilibrium pattern was detected across a total of 88 polymorphisms and 15 haplotype-tag SNPs (htSNPs) were identified. These htSNPs were profiled in a cohort of Chinese nasopharyngeal cancer (NPC) patients (n= 50). Genotypic-phenotypic analysis showed that a haplotypic construct comprising of four variants [IVS4+76G>A, 699G>A(Met233Ile), IVS12-5676A>G, and *347_*348insA] was the critical determinant of docetaxel disposition. This study suggests that the comprehensive screening and haplotypic linkage analysis of SLCO1B3 can better elucidate its pharmacogenetic effects on interpatient variability of docetaxel and other putative drug substrates. Further studies are warranted in cancer patients belonging to other ethnic groups. AIMS To completely screen the SLCO1B3 gene in three distinct healthy Asian populations (Chinese, Malay and Indian, n= 168) and investigate the influence of haplotype-tag SNPs (htSNPs) on docetaxel disposition in 50 nasopharyngeal carcinoma patients. METHODS: Genomic DNA of individuals was screened for SLCO1B3 polymorphisms by direct sequencing. htSNPs were derived based on the sequence clustering algorithm and profiled in the patients. Population based genetic association analysis was performed using Haplostats package implemented in R and PLINK. RESULTS: A strong linkage disequilibrium pattern was detected across a total of 88 polymorphisms and 15-htSNPs were identified. The SLCO1B3 haplotypic region comprising seven htSNPs was found to be significantly associated with docetaxel clearance (P= 0.003). Conditional haplotype analyses revealed that the haplotypic constructs comprising the IVS4+76G>A, 699G>A(Met233Ile), IVS12-5676A>G, and *347_*348insA polymorphisms were critical determinants of variability in docetaxel disposition [clearance and area under the plasma concentration-time curve (AUC(0,∞)): r(2) = 29% and 22%, respectively]. Patients harbouring the GAG*347insA haplotype were significantly associated with a 30% decrease in clearance and a 40% increase in AUC(0,∞) of docetaxel compared with patients harbouring the reference haplotype, GGA*347wt (P= 0.025 and 0.018, respectively). In contrast, a 50% higher clearance was observed in patients carrying the GAG*347wt haplotype compared with those with the reference haplotype (P= 0.002). The functional SLCO1B3 haplotypic constructs included the widely studied Met233Ile variant and *347_*348insA located in the putative miR-890 binding site in the 3'-untranslated region which may influence the transport characteristics of SLCO1B3. CONCLUSIONS: This study highlights the importance of SLCO1B3 polymorphic variations in influencing docetaxel disposition in nasopharyngeal carcinoma patients.

Clinical utility of thiopurine metabolite monitoring in inflammatory bowel disease and its impact on healthcare utilization in Singapore.

Background and Aim: Thiopurines are recommended for maintenance of steroid-free remission (SFR) in inflammatory bowel disease (IBD). Thiopurine metabolite monitoring (MM) is increasingly used in the West but remains novel in Singapore, with limited information on its therapeutic and economic benefits. Hence, this study aims to investigate MM's clinical utility and its impact on healthcare resource utilization in Singaporean IBD patients. Methods: A retrospective observational study was conducted at Singapore General Hospital outpatient IBD Centre. Patients with IBD, baseline MM during 2014-2017, and weight-based thiopurine doses for ≥4 weeks were followed up for 1 year. Actions were taken to optimize therapy, and metabolite levels before and after the first action were documented. Outcomes assessed included SFR, no therapy escalation or surgery, healthcare resource utilization, and direct healthcare costs. Results: Ninety IBD patients (50 Crohn's disease, 40 ulcerative colitis) were included. Among them, 40% had baseline metabolite levels within therapeutic range, 31.1% sub-therapeutic, 21.1% supra-therapeutic, and 7.8% shunters. Repeated MM with subsequent dose optimization helped 67.2% of patients achieve therapeutic levels after 1 year. Overall, 87.8% of patients achieved SFR and 90% had no therapy escalation or surgery. Despite greater outpatient visits and laboratory investigations with MM, the median total healthcare costs at 1 year only increased marginally (S$6407.66 [shunters] vs S$5215.20 [supra-therapeutic] vs S$4970.80 [sub-therapeutic] vs S$4370.48 [control (within therapeutic range)], P = 0.592). Conclusion: MM guided timely therapy escalation for non-responders, identification of non-adherence, and reversal of shunting. Therefore, it is a useful clinical tool to optimize thiopurines without significantly increasing healthcare costs.

Impact of CYP2D6, CYP3A5, CYP2C9 and CYP2C19 polymorphisms on tamoxifen pharmacokinetics in Asian breast cancer patients.

AIM: To investigate the impact of genetic polymorphisms in CYP2D6, CYP3A5, CYP2C9 and CYP2C19 on the pharmacokinetics of tamoxifen and its metabolites in Asian breast cancer patients. METHODS: A total of 165 Asian breast cancer patients receiving 20 mg tamoxifen daily and 228 healthy Asian subjects (Chinese, Malay and Indian; n= 76 each) were recruited. The steady-state plasma concentrations of tamoxifen and its metabolites were quantified using high-performance liquid chromatography. The CYP2D6 polymorphisms were genotyped using the INFINITI™ CYP450 2D6I assay, while the polymorphisms in CYP3A5, CYP2C9 and CYP2C19 were determined via direct sequencing. RESULTS: The polymorphisms, CYP2D6*5 and *10, were significantly associated with lower endoxifen and higher N-desmethyltamoxifen (NDM) concentrations. Patients who were *1/*1 carriers exhibited 2.4- to 2.6-fold higher endoxifen concentrations and 1.9- to 2.1-fold lower NDM concentrations than either *10/*10 or *5/*10 carriers (P < 0.001). Similarly, the endoxifen concentrations were found to be 1.8- to 2.6-times higher in *1/*5 or *1/*10 carriers compared with *10/*10 and *5/*10 carriers (P≤ 0.001). Similar relationships were observed between the CYP2D6 polymorphisms and metabolic ratios of tamoxifen and its metabolites. No significant associations were observed with regards to the polymorphisms in CYP3A5, CYP2C9 and CYP2C19. CONCLUSIONS: The present study in Asian breast cancer patients showed that CYP2D6*5/*10 and *10/*10 genotypes are associated with significantly lower concentrations of the active metabolite of tamoxifen, endoxifen. Identifying such patients before the start of treatment may be useful in optimizing therapy with tamoxifen. The role of CYP3A5, CYP2C9 and CYP2C19 seem to be minor.

Extracellular vesicle drug occupancy enables real-time monitoring of targeted cancer therapy.

Current technologies to measure drug-target interactions require complex processing and invasive tissue biopsies, limiting their clinical utility for cancer treatment monitoring. Here we develop an analytical platform that leverages circulating extracellular vesicles (EVs) for activity-based assessment of tumour-specific drug-target interactions in patient blood samples. The technology, termed extracellular vesicle monitoring of small-molecule chemical occupancy and protein expression (ExoSCOPE), utilizes bio-orthogonal probe amplification and spatial patterning of molecular reactions within matched plasmonic nanoring resonators to achieve in situ analysis of EV drug dynamics. It measures changes in drug occupancy and protein composition in molecular subpopulations of EVs. When used to monitor various targeted therapies, the ExoSCOPE revealed EV signatures that closely reflected cellular treatment efficacy. We further applied the technology for clinical cancer diagnostics and treatment monitoring. Using a small volume of blood, the ExoSCOPE accurately classified disease status and rapidly distinguished between targeted treatment outcomes, within 24 h after treatment initiation.

Pan-Cancer Analysis of Ligand-Receptor Cross-talk in the Tumor Microenvironment.

Signaling between cancer and nonmalignant (stromal) cells in the tumor microenvironment (TME) is a key to tumor progression. Here, we deconvoluted bulk tumor transcriptomes to infer cross-talk between ligands and receptors on cancer and stromal cells in the TME of 20 solid tumor types. This approach recovered known transcriptional hallmarks of cancer and stromal cells and was concordant with single-cell, in situ hybridization and IHC data. Inferred autocrine cancer cell interactions varied between tissues but often converged on Ephrin, BMP, and FGFR-signaling pathways. Analysis of immune checkpoints nominated interactions with high levels of cancer-to-immune cross-talk across distinct tumor types. Strikingly, PD-L1 was found to be highly expressed in stromal rather than cancer cells. Overall, our study presents a new resource for hypothesis generation and exploration of cross-talk in the TME. SIGNIFICANCE: This study provides deconvoluted bulk tumor transcriptomes across multiple cancer types to infer cross-talk in the tumor microenvironment.

A comparative proteomic analysis of HepG2 cells incubated by S(-) and R(+) enantiomers of anti-coagulating drug warfarin.

Warfarin is a commonly prescribed oral anti-coagulant with narrow therapeutic index. It interferes with vitamin K cycle to achieve anti-coagulating effects. Warfarin has two enantiomers, S(-) and R(+) and undergoes stereoselective metabolism, with the S(-) enantiomer being more effective. We reported that the intracellular protein profile in HepG2 cells incubated with S(-) and R(+) warfarin, using iTRAQ-coupled 2-D LC-MS/MS. In samples incubated with S(-) and R(+) warfarin alone, the multi-task protein Protein SET showed significant elevation in cells incubated with S(-) warfarin but not in those incubated with R(+) warfarin. In cells incubated with individual enantiomers of warfarin in the presence of vitamin K, protein disulfide isomerase A3 which is known as a glucose-regulated protein, in cells incubated with S(-) warfarin was found to be down-regulated compared to those incubated with R(+) warfarin. In addition, Protein DJ-1 and 14-3-3 Proteinsigma were down-regulated in cells incubated with either S(-) or R(+) warfarin regardless of the presence of vitamin K. Our results indicated that Protein DJ-1 may act as an enzyme for expression of essential enzymes in vitamin K cycle. Taken together, our findings provided molecular evidence on a comprehensive protein profile on warfarin-cell interaction, which may shed new lights on future improvement of warfarin therapy.

Obesity Alters Endoxifen Plasma Levels in Young Breast Cancer Patients: A Pharmacometric Simulation Approach.

Endoxifen is one of the most important metabolites of the prodrug tamoxifen. High interindividual variability in endoxifen steady-state concentrations (CSS,min ENDX ) is observed under tamoxifen standard dosing and patients with breast cancer who do not reach endoxifen concentrations above a proposed therapeutic threshold of 5.97 ng/mL may be at a 26% higher recurrence risk compared with patients with endoxifen concentrations exceeding this value. In this investigation, 10 clinical tamoxifen studies were pooled (1,388 patients) to investigate influential factors on CSS,min ENDX using nonlinear mixed-effects modeling. Age and body weight were found to significantly impact CSS,min ENDX in addition to CYP2D6 phenotype. Compared with postmenopausal patients, premenopausal patients had a 30% higher risk for subtarget CSS,min ENDX at tamoxifen 20 mg per day. In treatment simulations for distinct patient subpopulations, young overweight patients had a 3.1-13.8-fold higher risk for subtarget CSS,min ENDX compared with elderly low-weight patients. Considering ever-rising obesity rates and the clinical importance of tamoxifen for premenopausal patients, this subpopulation may benefit most from individualized tamoxifen dosing.

Polymorphism of human cytochrome P450 enzymes and its clinical impact.

Pharmacogenetics is the study of how interindividual variations in the DNA sequence of specific genes affect drug response. This article highlights current pharmacogenetic knowledge on important human drug-metabolizing cytochrome P450s (CYPs) to understand the large interindividual variability in drug clearance and responses in clinical practice. The human CYP superfamily contains 57 functional genes and 58 pseudogenes, with members of the 1, 2, and 3 families playing an important role in the metabolism of therapeutic drugs, other xenobiotics, and some endogenous compounds. Polymorphisms in the CYP family may have had the most impact on the fate of therapeutic drugs. CYP2D6, 2C19, and 2C9 polymorphisms account for the most frequent variations in phase I metabolism of drugs, since almost 80% of drugs in use today are metabolized by these enzymes. Approximately 5-14% of Caucasians, 0-5% Africans, and 0-1% of Asians lack CYP2D6 activity, and these individuals are known as poor metabolizers. CYP2C9 is another clinically significant enzyme that demonstrates multiple genetic variants with a potentially functional impact on the efficacy and adverse effects of drugs that are mainly eliminated by this enzyme. Studies into the CYP2C9 polymorphism have highlighted the importance of the CYP2C9*2 and *3 alleles. Extensive polymorphism also occurs in other CYP genes, such as CYP1A1, 2A6, 2A13, 2C8, 3A4, and 3A5. Since several of these CYPs (e.g., CYP1A1 and 1A2) play a role in the bioactivation of many procarcinogens, polymorphisms of these enzymes may contribute to the variable susceptibility to carcinogenesis. The distribution of the common variant alleles of CYP genes varies among different ethnic populations. Pharmacogenetics has the potential to achieve optimal quality use of medicines, and to improve the efficacy and safety of both prospective and currently available drugs. Further studies are warranted to explore the gene-dose, gene-concentration, and gene-response relationships for these important drug-metabolizing CYPs.

PXR pharmacogenetics: association of haplotypes with hepatic CYP3A4 and ABCB1 messenger RNA expression and doxorubicin clearance in Asian breast cancer patients.

PURPOSE: To characterize pregnane X receptor (PXR) polymorphic variants in healthy Asian populations [Chinese, Malay and Indian (n=100 each)], and to investigate the association between PXR haplotypes and hepatic mRNA expression of PXR and its downstream target genes, CYP3A4 and ABCB1, as well as their influence on the clearance of doxorubicin in Asian breast cancer patients. EXPERIMENTAL DESIGN: PXR genotyping was done by direct DNA sequencing, and PXR haplotypes and haplotype clusters were derived by expectation-maximization algorithm. Genotype-phenotype correlations were done using Mann-Whitney U test and Kruskal-Wallis test. RESULTS: Significant interethnic variations were observed in PXR pharmacogenetics among the three Asian ethnic groups. The expression of PXR mRNA in liver tissues harboring the PXR*1B haplotype clusters was 4-fold lower compared with the non-PXR*1B (*1A + *1C) haplotype clusters [PXR*1B versus PXR*1A; P=0.015; PXR*1B versus PXR*1C; P=0.023]. PXR*1B-bearing liver tissues were associated with significantly lower expression of CYP3A4 (PXR*1B versus non-PXR*1B, P=0.030) and ABCB1 (PXR*1B versus non-PXR*1B, P=0.060) compared with non-PXR*1B-bearing liver tissues. Doxorubicin clearance in breast cancer patients harboring the PXR*1B haplotypes was significantly lower compared with patients carrying the non-PXR*1B haplotypes [PXR*1B versus non-PXR*1B, CL/BSA (L h(-1) m(-2)): 20.84 (range, 8.68-29.24) versus 24.85 (range, 13.80-55.66), P=0.022]. CONCLUSIONS: This study showed that PXR*1B was associated with reduced hepatic mRNA expression of PXR and its downstream targets, CYP3A4 and ABCB1. Genotype-phenotype correlates in breast cancer patients showed PXR*1B to be significantly associated with lower doxorubicin clearance, suggesting that PXR haplotype constitution could be important in influencing interindividual and interethnic variations in disposition of its putative drug substrates.

CBR1 and CBR3 pharmacogenetics and their influence on doxorubicin disposition in Asian breast cancer patients.

The present study aimed to identify polymorphic genes encoding carbonyl reductases (CBR1, CBR3) and investigate their influence on doxorubicin disposition in Asian breast cancer patients (n = 62). Doxorubicin (60 mg/m(2)) was administered every 3 weeks for four to six cycles and the pharmacokinetic parameters were estimated using non-compartmental analysis (WinNonlin). The Mann-Whitney U-test was used to assess genotypic-phenotypic correlations. Five CBR1 (-48G>A, c.219G>C, c.627C>T, c.693G>A, +967G>A) and CBR3 (c.11G>A, c.255C>T, c.279C>T, c.606G>A, c.730G>A) polymorphisms were identified. The CBR1 D2 diplotypes were characterized by the presence of at least one variant allele at the c.627C>T and +967G>A loci. Patients in the CBR1 D1 diplotype group had significantly higher clearance (CL) normalized to body surface area (BSA) (CL/BSA[L/h/m(2)]: median 25.09; range 16.44-55.66) and significantly lower exposure levels; area under curve (AUC(0-infinity)/dose/BSA [h/m(5)]; median 15.08; range 6.18-38.03) of doxorubicin compared with patients belonging to the CBR1 D2 diplotype group (CL/BSA[L/h/m(2)]; median 20.88; range 8.68-31.79, P = 0.014; and AUC(0-infinity)/dose/BSA[h/m(5)]; median 21.35; range 9.82-67.17, P = 0.007 respectively). No significant influence of CBR3 polymorphisms on the pharmacokinetics of doxorubicin were observed in Asian cancer patients. The present exploratory study shows that CBR1 D2 diplotypes correlate with significantly higher exposure levels of doxorubicin, suggesting the possibility of lowered intracellular conversion to doxorubicinol in these patients. Further evaluation of carbonyl reductase polymorphisms in influencing the treatment efficacy of doxorubicin-based chemotherapy in Asian cancer patients are warranted.