Affect Drug Efficacy Research Articles

Inhibition of Lysyl Oxidases Improves Drug Diffusion and Increases Efficacy of Cytotoxic Treatment in 3D Tumor Models.

Tumors are characterized by a rigid, highly cross-linked extracellular matrix (ECM), which impedes homogeneous drug distribution and potentially protects malignant cells from exposure to therapeutics. Lysyl oxidases are major contributors to tissue stiffness and the elevated expression of these enzymes observed in most cancers might influence drug distribution and efficacy. We examined the effect of lysyl oxidases on drug distribution and efficacy in 3D in vitro assay systems. In our experiments elevated lysyl oxidase activity was responsible for reduced drug diffusion under hypoxic conditions and consequently impaired cytotoxicity of various chemotherapeutics. This effect was only observed in 3D settings but not in 2D-cell culture, confirming that lysyl oxidases affect drug efficacy by modification of the ECM and do not confer a direct desensitizing effect. Both drug diffusion and efficacy were strongly enhanced by inhibition of lysyl oxidases. The results from the in vitro experiments correlated with tumor drug distribution in vivo, and predicted response to therapeutics in murine tumor models. Our results demonstrate that lysyl oxidase activity modulates the physical barrier function of ECM for small molecule drugs influencing their therapeutic efficacy. Targeting this process has the potential to significantly enhance therapeutic efficacy in the treatment of malignant diseases.

A Pharmacometabonomic Approach To Predicting Metabolic Phenotypes and Pharmacokinetic Parameters of Atorvastatin in Healthy Volunteers.

Genetic polymorphism and environment each influence individual variability in drug metabolism and disposition. It is preferable to predict such variability, which may affect drug efficacy and toxicity, before drug administration. We examined individual differences in the pharmacokinetics of atorvastatin by applying gas chromatography-mass spectrometry-based metabolic profiling to predose plasma samples from 48 healthy volunteers. We determined the level of atorvastatin in plasma using liquid chromatography-tandem mass spectrometry. With the endogenous molecules, which showed a good correlation with pharmacokinetic parameters, a refined partial least-squares model was calculated based on predose data from a training set of 36 individuals and exhibited good predictive capability for the other 12 individuals in the prediction set. In addition, the model was successfully used to predictively classify individual pharmacokinetic responses into subgroups. Metabolites such as tryptophan, alanine, arachidonic acid, 2-hydroxybutyric acid, cholesterol, and isoleucine were indicated as candidate markers for predicting by showing better predictive capability for explaining individual differences than a conventional physiological index. These results suggest that a pharmacometabonomic approach offers the potential to predict individual differences in pharmacokinetics and therefore to facilitate individualized drug therapy.

Abstract 410: SPARC expression enhances cellular aggregation and resistance to gemcitabine in pancreatic cancer cells

Abstract Pancreatic cancer (PaCa) is a very aggressive disease with a high mortality rate, characterized by a survival time of only few months after diagnosis. Pancreatic cancers also demonstrate great resistance to chemotherapeutic regimes, associated with an extensive desmoplastic reaction. The matricelular protein SPARC is involved in the interaction between the cell and the extracellular matrix, and its expression has been associated with worse prognosis in general, and in patients treated with gemcitabine. To evaluate its role in pancreatic cancer and chemotherapeutic resistance, we overexpressed SPARC in the SPARC-negative pancreatic cancer cells lines Miapaca2, Sw1990, and Panc1. The in vitro growth of two stable clones obtained from the different cell lines was compared with eGFP-transduced controls. No significant differences were observed in the 2D in vitro growth or the clonogenic capacity between pancreatic cancer cells expressing or not expressing SPARC. However, cell growth in 3D spheroid culture was markedly different. Indeed, SPARC-expressing cells exhibited more compact structures, with 45% reduction in spheroid size compared to control eGFP-expressing cells. This could partially be explained by the fact that the SPARC-expressing cells themselves exhibited more than 50% reduction in their size compared to the eGFP cells. While SPARC expression in pancreatic cancer cells did not affect Gemcitabine EC50 in 2D culture, SPARC-positive Panc1 and SW1990 cells exhibited six to ten times increased EC50 in 3D spheroids. Because the cell-cell interactions could potentially affect drug efficacy, and because increased resistance to gemcitabine has been associated with epithelial-mesenchymal transition (EMT), we analyzed the expression of EMT-associated genes (SNAI1 and OCLN), and genes also involved in cellular junctions (CDH1 and OCLN). SPARC-positive pancreatic cancer cells down regulated the expression of SNAI1 and CDH2, while CDH1 and OCLN were up-regulated Taken together, these data indicate that SPARC expression in PaCa cell lines diminishes cells size and modulates gemcitabine resistance in 3D models of cell culture, possibly through the modulation of epithelial genes related to cell-cell connections and EMT. Citation Format: Edgardo Salvatierra, Elvia Rivas, Leandro Guttlein, Emily Robitschek, Andrea Llera, Osvaldo Podhajcer. SPARC expression enhances cellular aggregation and resistance to gemcitabine in pancreatic cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 410. doi:10.1158/1538-7445.AM2015-410

ERCC1 and CYP1B1 polymorphisms as predictors of response to neoadjuvant chemotherapy in estrogen positive breast tumors.

PurposeNeoadjuvant chemotherapy (NCT) using anthracyclines and taxanes is a standard treatment for locally advanced breast cancer. Efficacy of NCT is however variable among patients and predictive markers are expected to guide the selection of patients who will benefit from NCT. A promising approach stand with polymorphisms located in genes encoding drug transporters, drug metabolizing enzymes and target genes which can affect drug efficacy. Our study investigated the potential of 37 polymorphisms to predict response to NCT in breast cancer.Methods118 women with breast adenocarcinoma were treated with FEC100 and taxotere. Genotyping was performed on germline DNA using the BioMark platform (Fluidigm). Pathological complete response (pCR) according to Sataloff criteria was correlated to clinical characteristics and genotypes using univariate and multivariate analyses.Results25 patients (21.2%) reached complete pathologic response. pCR rate is increased in SBRIII (p = 0.009), ER negative (p = 0.005) and triple negative (p = 0.006) tumors. pCR rate is significantly increased for patients carrying at least one variant allele for BRCA1, ERCC1 or SLCO1B3, and for patients homozygous for CYP1B1. The combination of ERCC1 and CYP1B1 polymorphisms is a potential predictor of NCT response in breast cancer (pCR rate reached 50 vs 21.2% for unselected patients), and particularly in ER + breast cancer subtype where pCR rate reached 41.2 vs 13.5% for unselected patients.ConclusionsThis study is the first to report ERCC1, BRCA1 and SLCO1B3 as markers of response to NCT in breast cancer. ERCC1/CYP1B1 combination might be of particular interest to predict response to NCT in breast cancer and particularly to help NCT indication for ER+ breast tumors.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-015-1053-0) contains supplementary material, which is available to authorized users.

Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline for CYP2D6 and CYP2C19 Genotypes and Dosing of Selective Serotonin Reuptake Inhibitors.

Selective serotonin reuptake inhibitors (SSRIs) are primary treatment options for major depressive and anxiety disorders. CYP2D6 and CYP2C19 polymorphisms can influence the metabolism of SSRIs, thereby affecting drug efficacy and safety. We summarize evidence from the published literature supporting these associations and provide dosing recommendations for fluvoxamine, paroxetine, citalopram, escitalopram, and sertraline based on CYP2D6 and/or CYP2C19 genotype (updates at www.pharmgkb.org).

Analysis of loss-of-function variants and 20 risk factor phenotypes in 8,554 individuals identifies loci influencing chronic disease.

A typical human exome harbors dozens of loss-of-function (LOF) variants, which can lower disease risk factor levels and affect drug efficacy. We hypothesized that LOF variants are enriched in genes influencing risk factor levels and the onset of common chronic diseases, such as cardiovascular disease and diabetes. To test this hypothesis, we sequenced the exomes of 8,554 individuals and analyzed the effects of predicted LOF variants on 20 chronic disease risk factor phenotypes. Analysis of this sample as discovery and replication strata of equal size verified two relationships in well-studied genes (PCSK9 and APOC3) and identified eight new loci. Previously unknown relationships included elevated fasting glucose in carriers of heterozygous LOF variation in TXNDC5, which encodes a biomarker for type 1 diabetes progression, and apparent recessive effects of C1QTNF8 on serum magnesium levels. These data demonstrate the utility of functional-variant annotation within a large sample of deeply phenotyped individuals for gene discovery.

Involvement of CAR and PXR in the transcriptional regulation of CYP2B6 gene expression by ingredients from herbal medicines

1. Induction of hepatic drug-metabolizing enzymes can affect drug efficacy and cause toxicity. However, so far, limited information is available regarding the molecular mechanism how herbal medicines induce human CYP2B6, which metabolizes many of the clinically used therapeutics and activates several pro-carcinogens or toxicants. Accumulated evidence suggests that the human constitutive androstane receptor (hCAR) and the human pregnane X receptor (hPXR) play important roles in trans-activation of CYP2B6. In this study, we investigated the effects of 68 Chinese herbal ingredients on the receptor specificity of hPXR/hCAR-mediated CYP2B6 induction by luciferase reporter gene assays in transiently transfected HepG2 cells and on the expression of CYP2B6 in LS174T cells.2. The HepG2 cells were transiently transfected with human CYP2B6 luciferase promoter reporter plasmids along with hPXR or hCAR3. The results indicated that apigenin (Api), curcumol (Cur) and praeruptorin A (Pra A) were identified as potent activators of hPXR, and Pra A was also a ligand of hCAR.3. Furthermore, CYP2B6 mRNA expression in LS174T cells treated with the three herbal ingredients was determined by real-time polymerase chain reaction. By combining western blot and LC–MS/MS, CYP2B6 protein expression and catalytic activity induced by the three herbal ingredients were measured.4. Our observation showed Api and Cur up-regulated CYP2B6 expression by transactivation of hPXR, and Pra A acted as the ligand of both hPXR and hCAR to induce CYP2B6 expression.

Breast cancer resistance protein (ABCG2) in clinical pharmacokinetics and drug interactions: practical recommendations for clinical victim and perpetrator drug-drug interaction study design.

Breast cancer resistance protein (BCRP; ABCG2) limits intestinal absorption of low-permeability substrate drugs and mediates biliary excretion of drugs and metabolites. Based on clinical evidence of BCRP-mediated drug-drug interactions (DDIs) and the c.421C>A functional polymorphism affecting drug efficacy and safety, both the US Food and Drug Administration and European Medicines Agency recommend preclinical evaluation and, when appropriate, clinical assessment of BCRP-mediated DDIs. Although many BCRP substrates and inhibitors have been identified in vitro, clinical translation has been confounded by overlap with other transporters and metabolic enzymes. Regulatory recommendations for BCRP-mediated clinical DDI studies are challenging, as consensus is lacking on the choice of the most robust and specific human BCRP substrates and inhibitors and optimal study design. This review proposes a path forward based on a comprehensive analysis of available data. Oral sulfasalazine (1000 mg, immediate-release tablet) is the best available clinical substrate for intestinal BCRP, oral rosuvastatin (20 mg) for both intestinal and hepatic BCRP, and intravenous rosuvastatin (4 mg) for hepatic BCRP. Oral curcumin (2000 mg) and lapatinib (250 mg) are the best available clinical BCRP inhibitors. To interrogate the worst-case clinical BCRP DDI scenario, study subjects harboring the BCRP c.421C/C reference genotype are recommended. In addition, if sulfasalazine is selected as the substrate, subjects having the rapid acetylator phenotype are recommended. In the case of rosuvastatin, subjects with the organic anion-transporting polypeptide 1B1 c.521T/T genotype are recommended, together with monitoring of rosuvastatin's cholesterol-lowering effect at baseline and DDI phase. A proof-of-concept clinical study is being planned by a collaborative consortium to evaluate the proposed BCRP DDI study design.

Chemotherapy Optimization in Leukemia: Selecting the Right Mathematical Models for the Right Biological Processes∗

Clinical chemotherapy dosage strategies for leukemia rely on weight/height calculations theoretically correlated to patient drug tolerance. However, over- and under- dosage still exist in clinical practice, which could be overcome by quantifying the actual fraction of cancer cells susceptible to be eradicated. In this work, we show how choosing models that are accurate enough in simulating the biological processes ultimately affecting drug efficacy is critical in order to disentangle patient to patient heterogeneity. Incorporating heterogeneity from measurable sources in such a manner brings us a step closer in our path towards the development of personalized rational therapies.

Short communication: The gain-of-function Y581S polymorphism of the ABCG2 transporter increases secretion into milk of danofloxacin at the therapeutic dose for mastitis treatment

The ATP-binding cassette transporter ABCG2 restricts the exposure of certain drugs and natural compounds in different tissues and organs. Its expression in the mammary gland is induced during lactation and is responsible for the active secretion of many compounds into milk, including antimicrobial agents. This particular function of ABCG2 may affect drug efficacy against mastitis and the potential presence of drug residues in the milk. Previous in vitro and in vivo studies showed increased transport of several compounds, including fluoroquinolones, by the bovine ABCG2 Y581S polymorphism. Our main purpose was to study the potential effect of this bovine ABCG2 polymorphism on the secretion into milk of the antimicrobial danofloxacin administered at the therapeutic dose of 6mg/kg used for mastitis treatment. In addition, the effect of this polymorphism on the relative mRNA and protein levels of ABCG2 by quantitative real-time PCR and Western blot were studied. Danofloxacin 18% (6mg/kg) was administered to 6 Y/Y homozygous and 5 Y/S heterozygous cows. Danofloxacin levels in milk and milk-to-plasma concentration ratios were almost 1.5- and 2-fold higher, respectively, in Y/S cows compared with the Y/Y cows, showing a higher capacity of this variant to transport danofloxacin into milk. Furthermore, the higher activity of this polymorphism is not linked to higher ABCG2 mRNA or protein levels. These results demonstrate the relevant effect of the Y581S polymorphism of the bovine ABCG2 transporter in the secretion into milk of danofloxacin after administration of 6mg/kg, with potentially important consequences for mastitis treatment and for milk residue handling.

Abstract 770: Gender differences in the expression of drug metabolizing enzymes in human liver tissues

Abstract Differences in pharmacokinetics and drug metabolism present a major challenge in treatment of diseases, such as cancer, as they contribute to variations that characterizes how well drugs respond. Variation in the expression of major drug metabolizing enzymes (DMEs) is associated with significant differences in the bioavailability, distribution, metabolism and clearance of drugs and other xenobiotics. Previous mice/rats studies have shown genetic variation, or polymorphism, in these DMEs is one of the most important causes of variable drug response. It is essential not just in terms of how they affects drug efficacy but in how drugs affect the enzymes. A particular drug may inhibit the metabolic activity of certain DMEs which may lead to deadly levels of drug concentration and an increase in the severity of adverse side effects. On the contrary, when enzymatic activity is induced, drug concentration may decrease, severely limiting its performance. Given the important role of DMEs in regulating the pharmacological and biological activity of drugs it is essential to understand the regulatory features that lead to individual differences in the DMEs expression. Several factors contribute to individual differences in DME expression and drug metabolism. One of which is the differences contributed due the sex/gender of the subjects. In order to understand how sex differences in human may differ in terms of expression in DME, we compared gene expression in male and female human liver tissues, the liver being an important drug metabolizing tissue. Microarray analysis and real time PCR were utilized to identify significant changes in DME expression in hepatic tissues. Microarray analysis identified 34 sex-differential metabolizing enzymes in normal human livers at the RNA level. Of these, we focused on the expression of five metabolizing enzymes: CYP2B6, CYP1A1, CYP11A1, UGT2B15, GST-alpha. These five genes play potential roles in how anti-cancer drugs are metabolized and eliminated from the liver. mRNA expression for these five metabolizing enzymes were significantly higher in normal male human livers compared to female. At the protein levels, significant differences were only shown in CYP2B6 (p<0.05), CYP1A1 (p<0.01) and UGT2B15 (p<0.05). CYP2B6, CYP1A1 and UGT2B15 protein expressions were significantly higher in male compared to age-matched female. There were no significant changes in the protein expression of CYP11A1 AND GST-alpha between age-matched male and female human liver tissues. These studies show gender differences in liver DME expression and provide further insights into how the expression of hepatic enzymes active in the metabolism of drugs may contribute to gender differences at the clinic level in drug efficacy and toxicity, especially with anticancer agents. Citation Format: Stancy J. Joseph, Tamara Nicolson, Honggang Wang, Beverly R. Word, George Hammons, Beverly Lyn-Cook. Gender differences in the expression of drug metabolizing enzymes in human liver tissues. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 770. doi:10.1158/1538-7445.AM2014-770

Study the effect of drug resident time on in vivo efficacy (844.6)

When developing a new drug, it is difficult to predict from in vitro parameters to in vivo efficacy. It is generally accepted that drugs with the strong interactions with their target are more likely to show better efficacy. Therefore, thermodynamic parameter: dissociation constant or inhibition constant (Ki) are often considered as the most important factor to be determined as the first screening to prioritize the drug candidates. However, the kinetic parameter: the dissociation rate constant (koff) of the drugs is often neglected although several reports suggested that koff is as important as or more than Ki to estimate in vivo efficacy.Soluble epoxide hydrolase (sEH) has been proven to play an important role on regulating important lipid mediators, epoxy‐polyunsaturated fatty acid. Inhibition of sEH has been showed to be beneficial to human health in several aspects, anti‐inflammatory, analgesic and promoting tissue regeneration. We recently synthesized a series of new sEH inhibitors with different Kis and koffs. These inhibitors will be used as tools to test if koff can predict in vivo efficacy as equal as or better than the Ki.Here, a series of inhibitors with improved in vitro efficacy will be reported. Our in vivo results suggested that koff is crucial parameters to affect drug efficacy in an alternate way.Grant Funding Source: National Institute of Environ‐ mental Health Sciences (NIEHS) grant ES002710

In vitro inhibition of metabolism but not transport of gliclazide and repaglinide by Cree medicinal plant extracts

Ethnopharmacological relevanceInteractions between conventional drug and traditional medicine therapies may potentially affect drug efficacy and increase the potential for adverse reactions. Cree traditional healing is holistic and patients may use medicinal plants simultaneously with the conventional drugs. However, there is limited information that these medicinal plants may interact with drugs and additional mechanistic information is required. In this study, extracts from traditionally used Cree botanicals were assessed for their potential interaction that could alter the disposition of two blood glucose lowering drugs, gliclazide (Diamicron) and repaglinide (Gluconorm) though inhibition of either metabolism or transport across cell membranes. Materials and methodsThe effect of 17 extracts on metabolism was examined in a human liver microsome assay by HPLC and individual cytochrome P450s 2C9, 2C19, 2C8 and 3A4 in a microplate fluorometric assay. Gliclazide, rhaponticin and its aglycone derivative, rhapontigenin were also examined in the fluorometric assay. The effect on transport was examined with 11 extracts using the intestinal epithelial Caco-2 differentiated cell monolayer model at times up to 180min. ResultsBoth blood glucose lowering medications, gliclazide and repaglinide traversed the Caco-2 monolayer in a time-dependent manner that was not affected by the Cree plant extracts. Incubation of the Cree plant extracts inhibited CYP2C9, 2C19, 2C8 and 3A4-mediated metabolism, and the formation of four repaglinide metabolites: M4, m/z 451-A, m/z 451-B and the glucuronide of repaglinide in the human liver microsome assay. Gliclazide caused no significant inhibition. Likewise, rhaponticin had little effect on the enzymes causing changes of less than 10% with an exception of 17% inhibition of CYP2C19. By contrast, the aglycone rhapontigenin showed the greatest effects on all CYP-mediated metabolism. Its inhibition ranged from a mean of 58% CYP3A4 inhibition to 89% inhibition of CYP2C9. While rhaponticin and the aglycone did not show significant effects on repaglinide metabolism, they demonstrated inhibition of gliclazide metabolism. The aglycone significantly affected levels of gliclazide and its metabolites. ConclusionThese studies demonstrate that the Cree plant extracts examined have the potential in vitro to cause drug interactions through effects on key metabolic enzymes.

Cytochrome P450 genetic polymorphisms of Mexican indigenous populations

This review focuses on the genetic polymorphisms of the cytochrome P450 (CYP) genes in Mexican indigenous populations, who are a part of the wide ethnic diversity of this country. These native groups have a particular historical trajectory that is different from the Mexican Mestizos. This variability may be reflected in the frequency distribution of polymorphisms in the CYP genes that encode enzymes involved in the metabolism of drugs and other xenobiotics. Therefore, these polymorphisms may affect drug efficacy and safety in indigenous populations in Mexico. The present study aimed to analyze the prevalence of CYP polymorphisms in indigenous Mexicans and to compare the results with studies in Mexican Mestizos. Because the extrapolation of pharmacogenetic data from Mestizos is not applicable to the majority of indigenous groups, pharmacogenetic studies directed at indigenous populations need to be developed. The Amerindians analyzed in this study showed a low phenotypic (CYP2D6) and genotypic (CYP2D6, CYP2C9) diversity, unlike Mexican Mestizos. The frequency of polymorphisms in the CYP1A1, CYP2C19, CYP2E1, and CYP3A4 genes was more similar among the Amerindians and Mexican Mestizos, with the exception of the CYP1A2 gene, whose *1F variant frequency in Mexican Amerindians was the highest described to date.

Role of Xenobiotic Metabolism Enzyme Gene Polymorphism in the Formation of Chemotherapy Resistance in Patients with Chronic Lymphoproliferative Diseases

Enzymes of the cytochrome P450 and GSTP1 families play a pivotal role in the metabolism of a wide variety of antitumor drugs and polymorphisms of genes encoding for metabolizing enzymes can affect drug efficacy and toxicity. We studied the associations between functionally significant gene polymorphisms CYP2C8, CYP2C9, CYP2C19, CYP3A5, and GSTP1 and clinical response to chemotherapy in patients with chronic lymphoproliferative diseases. Significant correlations with chemotherapy resistance were observed for CYP2C8 3 (OR=7.05; CI 95%=1.76-29.55) and CYP2C9 2 polymorphisms (OR=4.1; CI 95%=1.03-16.81). No significant association between chemotherapy resistance and other examined polymorphisms were found.

Association between Response to Albendazole Treatment and β-Tubulin Genotype Frequencies in Soil-transmitted Helminths

BackgroundAlbendazole (ABZ), a benzimidazole (BZ) anthelmintic (AH), is commonly used for treatment of soil-transmitted helminths (STHs). Its regular use increases the possibility that BZ resistance may develop, which, in veterinary nematodes is caused by single nucleotide polymorphisms (SNPs) in the β-tubulin gene at positions 200, 167 or 198. The relative importance of these SNPs varies among the different parasitic nematodes of animals studied to date, and it is currently unknown whether any of these are influencing BZ efficacy against STHs in humans. We assessed ABZ efficacy and SNP frequencies before and after treatment of Ascaris lumbricoides, Trichuris trichiura and hookworm infections.MethodsStudies were performed in Haiti, Kenya, and Panama. Stool samples were examined prior to ABZ treatment and two weeks (Haiti), one week (Kenya) and three weeks (Panama) after treatment to determine egg reduction rate (ERR). Eggs were genotyped and frequencies of each SNP assessed.FindingsIn T. trichiura, polymorphism was detected at codon 200. Following treatment, there was a significant increase, from 3.1% to 55.3%, of homozygous resistance-type in Haiti, and from 51.3% to 67.8% in Kenya (ERRs were 49.7% and 10.1%, respectively). In A. lumbricoides, a SNP at position 167 was identified at high frequency, both before and after treatment, but ABZ efficacy remained high. In hookworms from Kenya we identified the resistance-associated SNP at position 200 at low frequency before and after treatment while ERR values indicated good drug efficacy.ConclusionAlbendazole was effective for A. lumbricoides and hookworms. However, ABZ exerts a selection pressure on the β-tubulin gene at position 200 in T. trichiura, possibly explaining only moderate ABZ efficacy against this parasite. In A. lumbricoides, the codon 167 polymorphism seemed not to affect drug efficacy whilst the polymorphism at codon 200 in hookworms was at such low frequency that conclusions cannot be drawn.

Association of ERCC1 (rs11615) and DNASE2B (rs3738573) polymorphisms with pathologic complete response to neoadjuvant chemotherapy for HER2-overexpressing breast cancer.

536 Background: Pathological complete response (pCR) is the main prognostic factor after preoperative chemotherapy. Predictive factors of pCR are mainly histological type, hormonal status, HER2 overexpression. Single nucleotide polymorphisms (SNP) in genes encoding drug transporters, drug metabolizing enzymes and target genes can affect drug efficacy and may explain therapeutic failures. The aim of the study was to identify SNPs associated with pCR in breast cancer (BC) patients (PTS) with HER-2 overexpression and treated with sequential neoadjuvant chemotherapy. Methods: Among PTS treated with NCT and included between 2007 and 2012, 46 PTS had HER-2 overexpressing BC, mostly ductal carcinoma (91.3%), greater than or equal to T2 (97.7%) and N1 (65.2%).91.3% of PTS received 3 FEC 100 - 3 Taxotere and 18 cycles of trastuzumab (3-18). Genotyping of 46 SNPs was performed on germline DNA using real time PCR. pCR was correlated with clinicopathologic features and genotypes using logistic regression. Results: pCR was evaluable for 45 PTS according to Sataloff criteria: pCR rate was 40% (95% CI 25.7-55.7%) and was significantly associated with hormonal status: 60.9% in negative hormone receptor tumors and 18.2% in positive hormone receptor tumors (p = 0.004). Four SNPs were significantly associated with pCR. All patients homozygotes CC for ERCC1-rs11615 respond to NCT (p=0.024). The response rate was higher for patients homozygotes TT for NQO2-rs1143684 (59.1%; p=0.018), PTS carrying one or two C allele for DNASE2B-rs3738573 (50%; p=0.025) and PTS carrying one or two C allele for MDR1-rs1045642(51.5%; p=0.012). Conclusions: In this pilot study 4 SNPs were significantly associated with pCR and may be useful to predict response to NCT (Anthracyclines/Taxanes/Trastuzumab regimen) for HER-2 overexpressing breast tumors. Moreover, DNASE2B-rs3738573 and ERCC1-rs11615, two polymorphisms located in genes involved in DNA reparation, have never been described as predictive markers for BC neoadjuvant chemotherapy. (The first 3 authors contributed equally to this work.)

A semi-supervised approach to extract pharmacogenomics-specific drug–gene pairs from biomedical literature for personalized medicine

Personalized medicine is to deliver the right drug to the right patient in the right dose. Pharmacogenomics (PGx) is to identify genetic variants that may affect drug efficacy and toxicity. The availability of a comprehensive and accurate PGx-specific drug–gene relationship knowledge base is important for personalized medicine. However, building a large-scale PGx-specific drug–gene knowledge base is a difficult task. In this study, we developed a bootstrapping, semi-supervised learning approach to iteratively extract and rank drug–gene pairs according to their relevance to drug pharmacogenomics. Starting with a single PGx-specific seed pair and 20 million MEDLINE abstracts, the extraction algorithm achieved a precision of 0.219, recall of 0.368 and F1 of 0.274 after two iterations, a significant improvement over the results of using non-PGx-specific seeds (precision: 0.011, recall: 0.018, and F1: 0.014) or co-occurrence (precision: 0.015, recall: 1.000, and F1: 0.030). After the extraction step, the ranking algorithm further improved the precision from 0.219 to 0.561 for top ranked pairs. By comparing to a dictionary-based approach with PGx-specific gene lexicon as input, we showed that the bootstrapping approach has better performance in terms of both precision and F1 (precision: 0.251 vs. 0.152, recall: 0.396 vs. 0.856 and F1: 0.292 vs. 0.254). By integrative analysis using a large drug adverse event database, we have shown that the extracted drug–gene pairs strongly correlate with drug adverse events. In conclusion, we developed a novel semi-supervised bootstrapping approach for effective PGx-specific drug–gene pair extraction from large number of MEDLINE articles with minimal human input.

Investigation on modulation of human P-gp by multiple doses of Radix Astragali extract granules using fexofenadine as a phenotyping probe

EthnopharmacologyHerb–drug interactions may potentially affect drug efficacy and/or the likelihood of adverse drug reactions. Radix Astragali (RA) extract formulation is usually prescribed for long-term use for patients with immunodeficiency, diabetes, nephropathy or cardiovascular diseases. Its use in combination with P-glycoprotein (P-gp) substrates is possible in clinical practice. Currently there is little knowledge about whether concomitant use of RA extract has an influence on disposition of P-gp substrate. Aim of the studyThis study was to investigate whether continuous and multiple doses of RA extract granules had modulatory effects on human P-gp. Material and methodsA randomised, placebo-controlled, two-period crossover pharmacokinetic drug interaction study was conducted in healthy Chinese volunteers. Fexofenadine was used as a P-gp phenotyping probe. Fourteen volunteers received RA extract granules or placebo (4g bid) for 7 days and then received a single oral dose of 120mg fexofenadine. Fexofenadine plasma concentrations were determined by HPLC. Pharmacokinetic parameters were calculated by non-compartmental method and bioequivalence evaluation was performed. ResultsPharamcokinetic parameters in the placebo phase were as follows: T1/2 (3.75±1.47h), Cmax (745.11±137.41μg/L), Tmax (2.25±0.47h), AUC(0−t) (3894.27±923.45μgh/L), AUC(0−∞) (3993.84±912.97μgh/L). Pharamcokinetic parameters in the RA extract phase were as follows: T1/2 (4.00±1.24h), Cmax (709.44±170.03μg/L), Tmax (2.21±0.51h), AUC(0−t) (3832.72±1077.60μgh/L), AUC(0−∞) (3983.53±1019.83μgh/L). The influence of RA extract on fexofenadine Cmax and AUC lacks statistical significance. Fexofenadine in the two phases were bioequivalent. In the placebo phase, T1/2 of fexofenadine in ABCB1 3435T mutation allele carriers was longer compared to ABCB1 3435CC carriers (4.43±1.44h vs. 2.54±0.21h, p<0.05). However, RA extract pretreatment abolished such genotype-related difference due to the lengthened T1/2 in ABCB1 3435CC carriers. There was no association of the C3435T polymorphism with Cmax and AUC(0−t) in subjects with two pretreatments. ConclusionOne-week administration of RA extract granules did not have a statistically significant impact on systematic exposure to fexofenadine, suggesting that RA extract is not a potent modulator of P-gp in vivo. RA extract appears to have ABCB1 C3435T genotype-dependent inhibitory effect on elimination rather than absorption of a P-gp substrate. Further investigations are necessary in patients who receive long-term use of RA extract formulation and combined P-gp substrates, especially in those ABCB1 3435CC carriers.

Control over hygroscopic growth of saline aqueous aerosol using Pluronic polymer additives

The hygroscopic properties of an aerosol originating from a nebulizer solution can affect the extent of peripheral deposition within the respiratory tract, which in turn affects drug efficacy of drugs delivered to the lungs. Thus, the ability to tailor the degree and rate of hygroscopic growth of an aerosol produced by a nebulizer through modification of the formulation would serve to improve drug efficacy through targeted lung deposition. In this study, the kinetic and thermodynamic hygroscopic properties of sodium chloride aerosol mixed with commercially available Pluronic polymers, specifically F77 and F127, are reported using three complementary single aerosol analysis techniques, specifically aerosol optical tweezers, a double ring electrodynamic balance and a concentric cylinder electrodynamic balance. The F77 polymer is shown to have a predictable effect on the hygroscopic properties of the aerosol: the ability of the droplet to uptake water from the air depends on the solute weight percent of sodium chloride present in a linear dose dependant manner. Unlike the smaller F77, a non-linear relationship was observed for the larger molecular weight F127 polymer, with significant suppression of hygroscopic growth (>50% by mass) for solution aerosol containing even only 1 wt% of the polymer and 99 wt% sodium chloride. The suppression of growth is shown to be consistent with the formation of mixed phase aerosol particles containing hydrophilic inorganic rich domains and hydrophobic polymer rich domains that sequester some of the inorganic component, with the two phases responding to changes in relative humidity independently. This independence of coupling with the gas phase is apparent in both the equilibrium state and the kinetics of water evaporation/condensation. By starting with a saline nebulizer solution with a concentration of F127 ∼10(-2)mM, a 12% reduction in the radius of all aerosol produced at a relative humidity (RH) of 84% is possible. The difference in diameter is RH dependent, and may be much greater at higher humidities. These findings suggest that the addition of μM concentrations of larger Pluronic polymers to nebulizer formulations may greatly reduce the size of aerosols produced.