TPMT and NUDT15 Variants Predict Discontinuation of Azathioprine for Myelotoxicity in Patients with Inflammatory Disease: Real-World Clinical Results.

Azathioprine is used frequently to treat several inflammatory conditions. However, treatment is limited by adverse events-in particular, myelotoxicity. Thiopurine-S-methyltransferase (TPMT) and nudix hydrolase-15 (NUDT15) are enzymes involved in azathioprine metabolism; variants in the genes encoding these enzymes increase the risk for azathioprine myelotoxicity. The Clinical Pharmacogenetics Implementation Consortium (CPIC) has recommended dose adjustments based on the results of TPMT and NUDT15 genotyping. However, little is known about the importance of this genetic information in routine clinical care. We hypothesized that in patients with inflammatory diseases, TPMT and NUDT15 genotype data predict the risk of discontinuing azathioprine due to myelotoxicity. This was a retrospective cohort study in 1,403 new adult azathioprine users for the management of inflammatory conditions for whom we had genetic information and clinical data. Among patients who discontinued azathioprine, we adjudicated the reason(s). Genotyping was performed using the Illumina Infinium Expanded Multi-Ethnic Genotyping Array plus custom content. We used CPIC guidelines to determine TPMT and NUDT15 metabolizer status; patients were grouped as either: (i) poor/intermediate, or (ii) normal/indeterminate metabolizers. We classified 110 patients as poor/intermediate, and 1,293 patients as normal/indeterminate metabolizers. Poor/intermediate status was associated with a higher risk for azathioprine discontinuation due to myelotoxicity compared to normal/indeterminate metabolizers (hazard ratio (HR) = 2.90, 95% confidence interval (CI): 1.58-5.31, P = 0.001). This association remained significant after adjustment for race, age at initiation, sex, primary indication, and initial daily dose of azathioprine (adjusted HR (aHR) = 2.67, 95% CI: 1.44-4.94, P = 0.002). In conclusion, TPMT and NUDT15 metabolizer status predicts discontinuation due to myelotoxicity for patients taking azathioprine for inflammatory conditions.

The role of genetic polymorphisms in STIM1 and ORAI1 for erythropoietin resistance in patients with renal failure.

ABSTRACT: Anemia is a common complication in patients with renal failure. While erythropoietin is commonly used to treat anemia, some patients exhibit a poor response to erythropoietin. Since store-operated calcium channel (SOC) signaling is one of the erythropoietin activated pathways, we aimed to investigate the association between the genetic polymorphisms of SOC signaling pathway and erythropoietin resistance in patients with renal failure.Four tagging single nucleotide polymorphisms in STIM1 and five in ORAI1 were selected in this study. Genotyping was performed with the TaqMan Allelic Discrimination assay and the association of individual tagging single nucleotide polymorphisms with erythropoietin resistance was analyzed by multivariable adjusted random intercepts model.194 patients were enrolled in this study. The mean age of participants is 68 years, and 56% were men. The mean erythropoietin resistance index was 9.04 ±â€Š4.51 U/Kg/week/g/dL. We found that patients with the AA genotype of rs1561876 in STIM1, and the CC or CT genotypes of rs6486795 in ORAI1, were associated with increased risk of erythropoietin resistance. Functional annotation of expression quantitative trait loci revealed that the AA genotype of rs1561876 in STIM1 has a relatively lower expression of ribonucleotide reductase catalytic subunit M1 in skeletal muscle, while the CC genotype of rs6486795 in ORAI1 has a relatively higher expression of ORAI1 in the whole blood and thyroid.Overall, we demonstrate a significant association between erythropoietin resistance and genetic polymorphisms of STIM1 and ORAI1. Annotation prediction revealed the importance of SOC-mediated calcium signaling for erythropoietin resistance.

Drug metabolising enzyme polymorphisms and chemotherapy-related ovarian failure in young breast cancer survivors.

Cyclophosphamide is associated with chemotherapy-related ovarian failure (CROF) in breast cancer survivors, however little is known about predicting individual risks. We sought to identify genetic alleles as biomarkers for risk of CROF after cyclophosphamide treatment. One hundred fifteen premenopausal women with newly diagnosed breast cancer were genotyped for single nucleotide polymorphisms (SNPs) in genes involved in cyclophosphamide activation (CYP3A4 and CYP2C19) and detoxification (GSTP1 and GSTA1). Patients prospectively completed menstrual diaries. With median follow up of 808 days, 28% experienced CROF. Survivors homozygous for the GSTA1 minor allele had lower hazards for developing CROF (HR 0.22 [95% CI 0.05-0.94], p=.04), while survivors homozygous for the CYP2C19 minor allele had higher hazards for developing CROF (HR 4.5 [95% CI 1.5-13.4], p=.007) compared to patients with at least one major allele. In separate multivariable models adjusting for age and tamoxifen use, the associations were no longer statistically significant (GSTA1 HR 0.24 [95% CI 0.06-1.0], p=.05; CYP2C19 HR 2.5 [0.8-7.6], p=.11). CYP3A4 and GSTP1 SNPs were not significantly related to CROF. In younger breast cancer survivors undergoing cyclophosphamide-based chemotherapy, genetic variation in CYP2C19 and GSTA1 merits further study to determine its relationship with CROF.IMPACT STATEMENTWhat is already known on this subject? Young breast cancer survivors face important potential implications of chemotherapy-related ovarian failure (CROF). Little is known about individual risk for CROF. Cyclophosphamide, a particularly gonadotoxic drug commonly used in breast cancer treatment, is metabolised by various cytochrome p450 enzymes. Studies have shown genetic variation in p450 enzymes is associated with differential clinical outcomes after cyclophosphamide treatment: breast cancer patients homozygous for GSTA1 minor allele had improved overall survival; lupus patients homozygous for CYP2C19 minor allele had increased risk for CROF; and CYP3A4*1B I was associated with decreased risk for CROF.What do the results of this study add? We show a surprising opposite trend for the risk of CROF in breast cancer patients with GSTA1 and CYP2C19 variants, while we did not show a significant risk for genetic variation in CYP3A4 (which had previously been shown to have a protective effect) or GSTP1.What are the implications of these findings for clinical practice and/or further research? This study shows the complexity of genetic variation in predicting outcomes to treatment. We advocate for future replicative studies to potentially validate GSTA1 and CYP2C19 and definitively negate CYP3A4 and GSTP1 as biomarkers for risk of CROF after cyclophosphamide treatment. Understanding genetic variation in chemotherapy metabolism has the potential to individualise treatment regimens to maximise efficacy and minimise toxicity.

CYP2C19 polymorphism has no correlation with the efficacy and safety of thalidomide in the treatment of immune-related bowel disease.

OBJECTIVE: To explore the relationship between hepatic cytochrome P450 2C19 (CYP2C19) gene polymorphisms and the effectiveness and safety of thalidomide in the treatment of patients with immune-related bowel disease (IRBD). METHODS: CYP2C19 variants in 79 patients treated with thalidomide were analyzed using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The clinical response and adverse events of the thalidomide treatment were recorded. The potential influences of the CYP2C19 genotype polymorphisms on the clinical efficacy and adverse events of thalidomide were then investigated. RESULTS: Altogether 79 patients with IRBD (70 with Crohn's disease, three with ulcerative colitis and six with Behcet's disease) receiving thalidomide therapy were recruited from January 2013 to February 2015 in a tertiary IBD center in China. Overall, 21.5% (17/79) of these patients had CYP2C19 poor metabolizers genotype (PM). The overall response rate and the incidence of adverse events of CYP2C19 extensive metabolizers genotype were not significantly different from that of the PM when IRBD patients were treated with thalidomide (P = 0.517 and 0.816, respectively). CONCLUSION: CYP2C19 polymorphisms do not seem to be associated with efficacy of thalidomide and the incidence of adverse events in treating IRBD.

Impact of genetic polymorphisms determining leukocyte/neutrophil count on chemotherapy toxicity.

Neutropenia and infection are major dose-limiting side effects of chemotherapy. The risk of initial infection and subsequent complications are directly related to the depth and duration of neutropenia. Recent genome-wide association studies identified variants in DARC and CXCL2 genes, and in ORMDL3-GSDMA-CSF3 locus on chromosome 17q21 that influence white blood cell and neutrophil counts in healthy individuals. To investigate whether polymorphisms in these loci in conjunction with chemotherapy may modulate risk of treatment complications, we analyzed 21 SNPs across these genes for an association with chemotherapy-related neutropenia and infection in 286 Caucasian children with acute lymphoblastic leukemia. After correction for multiple testing, DARC polymorphism rs3027012 in 5'-UTR was associated with higher risk of low absolute phagocyte count (APC<500 and <1000 cells per microliter, P=0.001 and P<0.0005, respectively) and hospitalization due to febrile neutropenia (P=0.002). Protective effect was instead seen for DARC rs12075 A to G substitution (P=0.004). The SNP rs3859192 in the GSDMA were associated with hospitalization due to infection (P=0.004); infection was also modulated in the additive manner by the CXCL2 rs16850408 (P=0.002). This study shows for the first time that the variations in DARC, GSDMA and CXCL2 genes may play a role in the onset of chemotherapy complications.

A quantitative shRNA screen identifies ATP1A1 as a gene that regulates cytotoxicity by aurilide B.

Genome-wide RNA interference (RNAi) with pooled and barcoded short-hairpin RNA (shRNA) libraries provides a powerful tool for identifying cellular components that are relevant to the modes/mechanisms of action (MoA) of bioactive compounds. shRNAs that affect cellular sensitivity to a given compound can be identified by deep sequencing of shRNA-specific barcodes. We used multiplex barcode sequencing technology by adding sample-specific index tags to PCR primers during sequence library preparation, enabling parallel analysis of multiple samples. An shRNA library screen with this system revealed that downregulation of ATP1A1, an α-subunit of Na+/K+ ATPase, conferred significant sensitivity to aurilide B, a natural marine product that induces mitochondria-mediated apoptosis. Combined treatment with ouabain which inhibits Na+/K+ ATPase by targeting α-subunits potentiated sensitivity to aurilide B, suggesting that ATP1A1 regulates mitochondria-mediated apoptosis. Our results indicate that multiplex sequencing facilitates the use of pooled shRNA library screening for the identification of combination drug therapy targets.

Gene variants in responsiveness to clopidogrel have no impact on clinical outcomes in Chinese patients undergoing percutaneous coronary intervention - A multicenter study.

BACKGROUND: Gene variants contribute to variability in individual responsiveness to clopidogrel and influence cardiovascular outcomes in Caucasian patients with acute coronary syndrome (ACS). However, limited data is available in Asian populations. METHODS: We resequenced 14 genes in metabolizing and activity pathway of clopidogrel in 138 patients with ACS and prospectively assessed the modulating effects of 13 variants possibly related to clopidogrel efficacy on one-year cardiovascular event occurrence in 5820 ACS patients after percutaneous coronary intervention (PCI). In addition, platelet aggregation rate was measured in 1084 participants and plasma levels of active metabolite were determined in 15 patients to test whether increasing clopidogrel maintenance doses increases active metabolite exposure. RESULTS: No significant associations were found between any of the tested variants and risk of cardiovascular events (P>0.05), although CYP2C19*2 carriers had slightly higher on-treatment platelet aggregation rate and lower active metabolite exposure compared with that of non-carriers (Median [IQR] 51.49 [35.43-66.75] vs. 49.05 [32.36-63.38], P=0.012) (means±SD AUC, 22.84±5.00 vs. 35.05±12.34, P=0.008). Switching from 75mg daily clopidogrel to 150mg daily fully overcomes low exposure to clopidogrel active metabolite in CYP2C19*2 carriers (means±SD AUC, 32.35±8.65 vs. 35.05±12.34, P=0.314). CONCLUSION: Different from Caucasian populations, genetic variants have no significant influence on clinical outcomes and have much milder effects on inhibition of platelet and active clopidogrel metabolite levels in Chinese patients with ACS after PCI, an effect which could be overcome with a dose escalation to 150mg daily.

Successful treatment with afatinib after grade 3 hepatotoxicity induced by both gefitinib and erlotinib in EGFR mutation-positive non-small cell lung cancer.

Hepatotoxicity is a major cause of the withdrawal of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) when treating EGFR mutation-positive non-small cell lung cancer (NSCLC). We report a case in which gefitinib- and elrotinib-induced severe hepatotoxicity arose in a patient with the uridine diphosphate glucuronosyltransferase isoform 1A1 (UGT1A1) and cytochrome p450 3A5 (CYP3A5) poor metabolizer phenotypes. Afatinib is not significantly metabolized by cytochrome p450-mediated pathways. We describe successful management of the patient's tumor by switching to afatinib. Evaluation of single nucleotide polymorphisms (SNPs) in metabolic enzymes might be useful to predict severe hepatotoxicity induced by EGFR-TKIs.

Influx transporter variants as predictors of cancer chemotherapy-induced toxicity: systematic review and meta-analysis.

AIM: Chemotherapeutic agents have been shown to increase lung patient survival, however their use may be limited by their serious adverse effects. We aimed to assess int impact of pharmacogenetic variation of influx transporters on inter-individual patient variation in adverse drug reactions. PATIENTS & METHODS: We conducted a meta-analysis and systemic review and identified 16 publications, totaling 1510 patients, to be eligible for review. RESULTS: Meta-analysis showed east-Asian patients expressing SLCO1B1 521T>C or 1118G>A to have a two- to fourfold increased risk of irinotecan-induced neutropenia but not diarrhea. American patients, expressing SLC19A1 IVS2(4935) G>A, were further associated with pemetrexed/gemcitabine-induced grade 3+ leukopenia. CONCLUSION: Future studies should look to robust validation of SLCO1B1 and SLC19A1 as prognostic markers in the management of lung cancer patients.

Genetic variation of CYP3A5 influences paclitaxel/carboplatin-induced toxicity in Chinese epithelial ovarian cancer patients.

Combination chemotherapy with platinum and taxane is the first-line treatment for ovarian cancer. The dose-limiting toxicities of these drugs include neuropathy, leukopenia, and neutropenia, but they exhibit substantial interindividual variability. This study investigated the relationship between CYP3A5 polymorphisms and paclitaxel/carboplatin-induced toxicity in Chinese epithelial ovarian cancer patients. Seventy-five patients with epithelial ovarian cancer were recruited. After combination chemotherapy, genotype analysis was conducted, and toxic effects were evaluated according to the Common Toxicity Criteria. A significant association was found between myelosuppression and the CYP3A5*3 genotype. CYP3A5*3/*1 patients showed a significantly higher risk of developing leukopenia (P < .001; Pearson's χ(2) test) and neutropenia (P < .001; Pearson's χ(2) test) than CYP3A5*3*3 patients. CYP3A5*3/*3 patients had significantly higher median leukocyte and neutrophil nadir counts than CYP3A5*3*1 patients (P < .001, Mann-Whitney U test). However, we did not observe an association between neuropathy and CYP3A5*3 in this study (P =.64; Pearson's χ(2) test). This is the first study to verify the influence of CYP3A5 polymorphisms on paclitaxel/carboplatin-induced toxicity in Chinese epithelial ovarian cancer patients. Our findings suggest that interindividual variability in paclitaxel/carboplatin-induced myelosuppression can be predicted by CYP3A5*3 genotyping and that incorporation of CYP3A5*3 genetic data in treatment selection could help to reduce myelosuppression events, thereby individualizing paclitaxel/carboplatin pharmacotherapy.