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Castro-Pearson S, Le CT, Luo X. Two-sample survival probability curves: A graphical approach for the analysis of time to event data in clinical trials. Contemp Clin Trials 2022; 115:106707. [PMID: 35176502 PMCID: PMC9018539 DOI: 10.1016/j.cct.2022.106707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 12/29/2021] [Accepted: 02/09/2022] [Indexed: 11/03/2022]
Abstract
With the aim to improve the communication of trial results, we introduce a novel graphical approach that complements the analysis of time to event outcomes in two-arm randomized trials. We define the so-called two-sample survival probability curve and propose a nonparametric estimator of the curve based on a random walk using Kaplan-Meier survival estimates for the two arms. We then use the estimated curve to visualize treatment effect as well as potential effect modification of factors of interest. We also propose to estimate two-sample survival probability curves within the framework of the Cox model to graphically assess model fit. The proposed two-sample survival probability plot puts trials in a standardized [0,1] × [0,1] space, allowing for a simple visualization of the main effect, effect modification, and the adequacy of a model fit.
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Nguyen VT, Braun A, Kraft J, Ta TMT, Panagiotaropoulou GM, Nguyen VP, Nguyen TH, Trubetskoy V, Le CT, Le TTH, Pham XT, Heuser-Collier I, Lam NH, Böge K, Hahne IM, Bajbouj M, Zierhut MM, Hahn E, Ripke S. Increasing sample diversity in psychiatric genetics - Introducing a new cohort of patients with schizophrenia and controls from Vietnam - Results from a pilot study. World J Biol Psychiatry 2022; 23:219-227. [PMID: 34449294 DOI: 10.1080/15622975.2021.1951474] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
OBJECTIVES Genome-Wide Association Studies (GWAS) of Schizophrenia (SCZ) have provided new biological insights; however, most cohorts are of European ancestry. As a result, derived polygenic risk scores (PRS) show decreased predictive power when applied to populations of different ancestries. We aimed to assess the feasibility of a large-scale data collection in Hanoi, Vietnam, contribute to international efforts to diversify ancestry in SCZ genetic research and examine the transferability of SCZ-PRS to individuals of Vietnamese Kinh ancestry. METHODS In a pilot study, 368 individuals (including 190 SCZ cases) were recruited at the Hanoi Medical University's associated psychiatric hospitals and outpatient facilities. Data collection included sociodemographic data, baseline clinical data, clinical interviews assessing symptom severity and genome-wide SNP genotyping. SCZ-PRS were generated using different training data sets: (i) European, (ii) East-Asian and (iii) trans-ancestry GWAS summary statistics from the latest SCZ GWAS meta-analysis. RESULTS SCZ-PRS significantly predicted case status in Vietnamese individuals using mixed-ancestry (R2 liability = 4.9%, p = 6.83 × 10-8), East-Asian (R2 liability = 4.5%, p = 2.73 × 10-7) and European (R2 liability = 3.8%, p = 1.79 × 10-6) discovery samples. DISCUSSION Our results corroborate previous findings of reduced PRS predictive power across populations, highlighting the importance of ancestral diversity in GWA studies.
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Zhang S, Chu H, Bickel WK, Le CT, Smith TT, Thomas JL, Donny EC, Hatsukami DK, Luo X. A Bayesian hierarchical model for individual participant data meta-analysis of demand curves. Stat Med 2022; 41:2276-2290. [PMID: 35194829 DOI: 10.1002/sim.9354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 01/27/2022] [Accepted: 01/29/2022] [Indexed: 11/07/2022]
Abstract
Individual participant data meta-analysis is a frequently used method to combine and contrast data from multiple independent studies. Bayesian hierarchical models are increasingly used to appropriately take into account potential heterogeneity between studies. In this paper, we propose a Bayesian hierarchical model for individual participant data generated from the Cigarette Purchase Task (CPT). Data from the CPT details how demand for cigarettes varies as a function of price, which is usually described as an exponential demand curve. As opposed to the conventional random-effects meta-analysis methods, Bayesian hierarchical models are able to estimate both the study-specific and population-level parameters simultaneously without relying on the normality assumptions. We applied the proposed model to a meta-analysis with baseline CPT data from six studies and compared the results from the proposed model and a two-step conventional random-effects meta-analysis approach. We conducted extensive simulation studies to investigate the performance of the proposed approach and discussed the benefits of using the Bayesian hierarchical model for individual participant data meta-analysis of demand curves.
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Shi L, Hatsukami DK, Koopmeiners JS, Le CT, Benowitz NL, Donny EC, Luo X. A mixed effects model for analyzing area under the curve of longitudinally measured biomarkers with missing data. Pharm Stat 2021; 20:1249-1264. [PMID: 34151513 DOI: 10.1002/pst.2146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 05/06/2021] [Accepted: 06/01/2021] [Indexed: 11/08/2022]
Abstract
A simple approach for analyzing longitudinally measured biomarkers is to calculate summary measures such as the area under the curve (AUC) for each individual and then compare the mean AUC between treatment groups using methods such as t test. This two-step approach is difficult to implement when there are missing data since the AUC cannot be directly calculated for individuals with missing measurements. Simple methods for dealing with missing data include the complete case analysis and imputation. A recent study showed that the estimated mean AUC difference between treatment groups based on the linear mixed model (LMM), rather than on individually calculated AUCs by simple imputation, has negligible bias under random missing assumptions and only small bias when missing is not at random. However, this model assumes the outcome to be normally distributed, which is often violated in biomarker data. In this paper, we propose to use a LMM on log-transformed biomarkers, based on which statistical inference for the ratio, rather than difference, of AUC between treatment groups is provided. The proposed method can not only handle the potential baseline imbalance in a randomized trail but also circumvent the estimation of the nuisance variance parameters in the log-normal model. The proposed model is applied to a recently completed large randomized trial studying the effect of nicotine reduction on biomarker exposure of smokers.
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Carmella SG, Heskin AK, Tang MK, Jensen J, Luo X, Le CT, Murphy SE, Benowitz NL, McClernon FJ, Vandrey R, Allen SS, Denlinger-Apte R, Cinciripini PM, Strasser AA, al’Absi M, Robinson JD, Donny EC, Hatsukami DK, Hecht SS. Longitudinal stability in cigarette smokers of urinary eicosanoid biomarkers of oxidative damage and inflammation. PLoS One 2019; 14:e0215853. [PMID: 31022220 PMCID: PMC6483352 DOI: 10.1371/journal.pone.0215853] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 04/09/2019] [Indexed: 12/14/2022] Open
Abstract
The urinary metabolites (Z)-7-[1R,2R,3R,5S)-3,5-dihydroxy-2-[(E,3S)-3-hydroxyoct-1-enyl]cyclopentyl]hept-5-enoic acid (8-iso-PGF2α), an F2-isoprostane and biomarker of oxidative damage, and "prostaglandin E2 metabolite" (PGE-M), a biomarker of inflammation, are elevated in cigarette smokers. However, there is little information in the literature on the longitudinal stability of these widely used biomarkers. In a large clinical trial involving 10 institutional sites, smokers were given, free of charge over a period of 20 weeks, Spectrum NRC600/601 research cigarettes containing 15.5 mg nicotine/g tobacco. All participants were instructed to smoke these cigarettes for the duration of the study. At weeks 4, 8, 12, 16, and 20, first morning urine voids were collected and analyzed for 8-iso-PGF2α and PGE-M using validated liquid chromatography-electrospray ionization-tandem mass spectrometry methods. The mean level of 8-iso-PGF2α at Week 4 was 1.34 ± 1.08 (S.D.) pmol/mg creatinine (N = 226) while that of PGE-M was 73.7 ± 113 (S.D.) pmol/mg creatinine (N = 232). The corresponding levels at Week 20 were 1.35 ± 0.93 (S.D.) pmol/mg creatinine (N = 209) for 8-iso-PGF2α and 74.2 ± 142 (S.D.) pmol/mg creatinine (N = 210) for PGE-M. There was variation in these values in the intervening weeks. The intra-class correlation coefficients (ICC) were 0.51 (95% CI, 0.45, 0.57) and 0.36 (0.30, 0.43), for 8-iso-PGF2α and PGE-M, respectively, indicating fair longitudinal stability for 8-iso-PGF2α and poorer longitudinal stability for PGE-M in cigarette smokers. Males had higher ICC values than females for both 8-iso-PGF2α and PGE-M. These results indicate that, in addition to cigarette smoking, endogenous processes of oxidative damage and inflammation influence the levels of these biomarkers over time among current smokers.
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Chen M, Carmella SG, Sipe C, Jensen J, Luo X, Le CT, Murphy SE, Benowitz NL, McClernon FJ, Vandrey R, Allen SS, Denlinger-Apte R, Cinciripini PM, Strasser AA, al’Absi M, Robinson JD, Donny EC, Hatsukami D, Hecht SS. Longitudinal stability in cigarette smokers of urinary biomarkers of exposure to the toxicants acrylonitrile and acrolein. PLoS One 2019; 14:e0210104. [PMID: 30608961 PMCID: PMC6319718 DOI: 10.1371/journal.pone.0210104] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 12/17/2018] [Indexed: 01/07/2023] Open
Abstract
The urinary metabolites cyanoethyl mercapturic acid (CEMA) and 3-hydroxypropyl mercapturic acid (3-HPMA) have been widely used as biomarkers of exposure to acrylonitrile and acrolein, respectively, but there are no published data on their consistency over time in the urine of cigarette smokers. We provided, free of charge over a 20 week period, Spectrum NRC600/601 research cigarettes to cigarette smokers in the control arm of a randomized clinical trial of the reduced nicotine cigarette. Urine samples were collected at weeks 4, 8, 12, 16, and 20 and analyzed for CEMA and 3-HPMA, and total nicotine equivalents (TNE) using validated methods. Creatinine-corrected intra-class correlation coefficients for CEMA, 3-HPMA, and TNE were 0.67, 0.46, and 0.68, respectively, indicating good longitudinal consistency for CEMA, while that of 3-HPMA was fair. A strong correlation between CEMA and TNE values was observed. These data support the use of CEMA as a reliable biomarker of tobacco smoke exposure. This is the first report of the longitudinal stability of the biomarkers of acrylonitrile and acrolein exposure in smokers. The data indicate that CEMA, the biomarker of acrylonitrile exposure, is consistent over time in cigarette smokers, supporting its use. While 3-HPMA levels were less stable over time, this biomarker is nevertheless a useful monitor of human acrolein exposure because of its specificity to this toxicant.
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Zhang Y, Luo X, Le CT, Ahluwalia JS, Thomas JL. Analysis of self-report and biochemically verified tobacco abstinence outcomes with missing data: a sensitivity analysis using two-stage imputation. BMC Med Res Methodol 2018; 18:170. [PMID: 30563473 PMCID: PMC6299502 DOI: 10.1186/s12874-018-0635-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 12/03/2018] [Indexed: 01/08/2023] Open
Abstract
Background Missing data are common in tobacco studies. It is well known that from the observed data alone, it is impossible to distinguish between missing mechanisms such as missing at random (MAR) and missing not at random (MNAR). In this paper, we propose a sensitivity analysis method to accommodate different missing mechanisms in cessation outcomes determined by self-report and urine validation results. Methods We propose a two-stage imputation procedure, allowing survey and urine data to be missing under different mechanisms. The motivating data were from a tobacco cessation trial examining the effects of the extended vs. standard Quit and Win contests and counseling vs. no counseling under a 2-by-2 factorial design. The primary outcome was 6-month biochemically verified tobacco abstinence. Results Our proposed method covers a wide spectrum of missing scenarios, including the widely adopted “missing = smoking” imputation by assuming a perfect smoking-missing correlation (an extreme case of MNAR), the MAR case by assuming a zero smoking-missing correlation, and many more in between. The analysis of the data example shows that the estimated effects of the studied interventions are sensitive to the different missing assumptions on the survey and urine data. Conclusions Sensitivity analysis has played a crucial role in assessing the robustness of the findings in clinical trials with missing data. The proposed method provides an effective tool for analyzing missing data introduced at two different stages of outcome assessment, the self-report and validation time. Our methods are applicable to trials studying biochemically verified abstinence from alcohol and other substances. Electronic supplementary material The online version of this article (10.1186/s12874-018-0635-2) contains supplementary material, which is available to authorized users.
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Hatsukami DK, Luo X, Jensen JA, al'Absi M, Allen SS, Carmella SG, Chen M, Cinciripini PM, Denlinger-Apte R, Drobes DJ, Koopmeiners JS, Lane T, Le CT, Leischow S, Luo K, McClernon FJ, Murphy SE, Paiano V, Robinson JD, Severson H, Sipe C, Strasser AA, Strayer LG, Tang MK, Vandrey R, Hecht SS, Benowitz NL, Donny EC. Effect of Immediate vs Gradual Reduction in Nicotine Content of Cigarettes on Biomarkers of Smoke Exposure: A Randomized Clinical Trial. JAMA 2018; 320:880-891. [PMID: 30193275 PMCID: PMC6372240 DOI: 10.1001/jama.2018.11473] [Citation(s) in RCA: 113] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Importance The optimal temporal approach for reducing nicotine to minimally or nonaddictive levels in all cigarettes sold in the United States has not been determined. Objectives To determine the effects of immediate vs gradual reduction in nicotine content to very low levels and as compared with usual nicotine level cigarettes on biomarkers of toxicant exposure. Design, Setting, and Participants A double-blind, randomized, parallel-design study with 2 weeks of baseline smoking and 20 weeks of intervention was conducted at 10 US sites. A volunteer sample of daily smokers with no intention to quit within 30 days was recruited between July 2014 and September 2016, with the last follow-up completed in March 2017. Interventions (1) Immediate reduction to 0.4 mg of nicotine per gram of tobacco cigarettes; (2) gradual reduction from 15.5 mg to 0.4 mg of nicotine per gram of tobacco cigarettes with 5 monthly dose changes; or (3) maintenance on 15.5 mg of nicotine per gram of tobacco cigarettes. Main Outcomes and Measures Between-group differences in 3 co-primary biomarkers of smoke toxicant exposure: breath carbon monoxide (CO), urine 3-hydroxypropylmercapturic acid (3-HPMA, metabolite of acrolein), and urine phenanthrene tetraol (PheT, indicator of polycyclic aromatic hydrocarbons) calculated as area under the concentration-time curve over the 20 weeks of intervention. Results Among 1250 randomized participants (mean age, 45 years; 549 women [44%]; 958 [77%] completed the trial), significantly lower levels of exposure were observed in the immediate vs gradual reduction group for CO (mean difference, -4.06 parts per million [ppm] [95% CI, -4.89 to -3.23]; P < .0055), 3-HPMA (ratio of geometric means, 0.83 [95% CI, 0.77 to 0.88]; P < .0055), and PheT (ratio of geometric means, 0.88 [95% CI, 0.83 to 0.93]; P < .0055). Significantly lower levels of exposure were observed in the immediate reduction vs control group for CO (mean difference, -3.38 [95% CI, -4.40 to -2.36]; P < .0055), 3-HPMA (ratio of geometric means, 0.81 [95% CI, 0.75 to 0.88]; P < .0055), and PheT (ratio of geometric means, 0.86 [95% CI, 0.81 to 0.92]; P < .0055). No significant differences were observed between the gradual reduction vs control groups for CO (mean difference, 0.68 [95% CI, -0.31 to 1.67]; P = .18), 3-HPMA (ratio of geometric means, 0.98 [95% CI, 0.91 to 1.06]; P = .64), and PheT (ratio of geometric means, 0.98 [95% CI, 0.92 to 1.04]; P = .52). Conclusions and Relevance Among smokers, immediate reduction of nicotine in cigarettes led to significantly greater decreases in biomarkers of smoke exposure across time compared with gradual reduction or a control group, with no significant differences between gradual reduction and control. Trial Registration clinicaltrials.gov Identifier: NCT02139930.
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Bustamante G, Ma B, Yakovlev G, Yershova K, Le CT, Jensen J, Hatsukami D, Stepanov I. Presence of the Carcinogen N'-Nitrosonornicotine in Saliva of E-cigarette Users. Chem Res Toxicol 2018; 31:731-738. [PMID: 30019582 PMCID: PMC8556657 DOI: 10.1021/acs.chemrestox.8b00089] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Many harmful constituents are present in e-cigarettes at much lower levels than in cigarette smoke, and the results of analysis of urinary biomarkers in e-cigarette users are consistent with these findings. However, understanding the health effects of chronic exposures to e-cigarette aerosols may require thinking beyond these comparisons. In this study, we investigated the endogenous formation of the tobacco-specific oral and esophageal carcinogen N'-nitrosonornicotine (NNN) in e-cigarette users. Salivary NNN, nornicotine, and nicotine as well as urinary tobacco biomarkers, including total NNN, were analyzed in 20 e-cigarette users, 20 smokers, and 19 nonsmokers. Nornicotine and NNN levels in e-cigarettes used by the study participants were also analyzed. The mean of NNN in saliva of e-cigarette users was 14.6 (±23.1) pg/mL, ranging from nonquantifiable (below the limit of quantitation, LOQ) to 76.0 pg/mL. In smokers, salivary NNN ranged from below LOQ to 739 pg/mL, with 80% of smokers having salivary NNN in the range of levels found in e-cigarette users. Consistent with a previous report, very low levels of urinary total NNN were present in only 5 out of 20 e-cigarette users (ranging from 0.001 to 0.01 pmol/mL urine). Only trace levels of NNN were found in e-cigarette liquids. Together, our findings demonstrate that NNN is formed endogenously in e-cigarette users. While the overall exposure to NNN in e-cigarette users is dramatically lower than in smokers, the known carcinogenic potency of NNN warrants further investigations into the potential consequences of its endogenous formation. Salivary NNN, rather than urinary total NNN, which accounts for only 1-3% of the NNN dose, should be used to monitor e-cigarette users' exposure to this carcinogen.
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Ho YY, Nhu Vo T, Chu H, LeSage MG, Luo X, Le CT. A Bayesian hierarchical model for demand curve analysis. Stat Methods Med Res 2018; 27:2401-2412. [PMID: 29984638 DOI: 10.1177/0962280216680651] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Drug self-administration experiments are a frequently used approach to assess the abuse liability and reinforcing property of a compound. It has been used to assess the abuse liabilities of various substances such as psychomotor stimulants and hallucinogens, food, nicotine, and alcohol. The demand curve generated from a self-administration study describes how demand of a drug or non-drug reinforcer varies as a function of price. With the approval of the 2009 Family Smoking Prevention and Tobacco Control Act, demand curve analysis provides crucial evidence to inform the US Food and Drug Administration's policy on tobacco regulation because it produces several important quantitative measurements to assess the reinforcing strength of nicotine. The conventional approach popularly used to analyze the demand curve data is individual-specific non-linear least square regression. The non-linear least square approach sets out to minimize the residual sum of squares for each subject in the dataset; however, this one-subject-at-a-time approach does not allow for the estimation of between- and within-subject variability in a unified model framework. In this paper, we review the existing approaches to analyze the demand curve data, non-linear least square regression, and the mixed effects regression and propose a new Bayesian hierarchical model. We conduct simulation analyses to compare the performance of these three approaches and illustrate the proposed approaches in a case study of nicotine self-administration in rats. We present simulation results and discuss the benefits of using the proposed approaches.
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Ho YY, Nhu Vo T, Chu H, Luo X, Le CT. A Bayesian hierarchical model for demand curve analysis. Stat Methods Med Res 2018; 27:2038-2049. [PMID: 29846147 DOI: 10.1177/0962280216673675] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Drug self-administration experiments are a frequently used approach to assessing the abuse liability and reinforcing property of a compound. It has been used to assess the abuse liabilities of various substances such as psychomotor stimulants and hallucinogens, food, nicotine, and alcohol. The demand curve generated from a self-administration study describes how demand of a drug or non-drug reinforcer varies as a function of price. With the approval of the 2009 Family Smoking Prevention and Tobacco Control Act, demand curve analysis provides crucial evidence to inform the US Food and Drug Administration's policy on tobacco regulation, because it produces several important quantitative measurements to assess the reinforcing strength of nicotine. The conventional approach popularly used to analyze the demand curve data is individual-specific non-linear least square regression. The non-linear least square approach sets out to minimize the residual sum of squares for each subject in the dataset; however, this one-subject-at-a-time approach does not allow for the estimation of between- and within-subject variability in a unified model framework. In this paper, we review the existing approaches to analyze the demand curve data, non-linear least square regression, and the mixed effects regression and propose a new Bayesian hierarchical model. We conduct simulation analyses to compare the performance of these three approaches and illustrate the proposed approaches in a case study of nicotine self-administration in rats. We present simulation results and discuss the benefits of using the proposed approaches.
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Zhao T, Luo X, Chu H, Le CT, Epstein LH, Thomas JL. A two-part mixed effects model for cigarette purchase task data. J Exp Anal Behav 2018; 106:242-253. [PMID: 27870106 DOI: 10.1002/jeab.228] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 10/05/2016] [Indexed: 11/11/2022]
Abstract
The Cigarette Purchase Task is a behavioral economic assessment tool designed to measure the relative reinforcing efficacy of cigarette smoking across different prices. An exponential demand equation has become a standard model for analyzing purchase task data, but its utility is compromised by its inability to accommodate values of zero consumption. We propose a two-part mixed effects model that keeps the same exponential demand equation for modeling nonzero consumption values, while providing a logistic regression for the binary outcome of zero versus nonzero consumption. Therefore, the proposed model can accommodate zero consumption values and retain the features of the exponential demand equation at the same time. As a byproduct, the logistic regression component of the proposed model provides a new demand index, the "derived breakpoint", for the price above which a subject is more likely to be abstinent than to be smoking. We apply the proposed model to data collected at baseline from college students (N = 1,217) enrolled in a randomized clinical trial utilizing financial incentives to motivate tobacco cessation. Monte Carlo simulations showed that the proposed model provides better fits than an existing model. We note that the proposed methodology is applicable to other purchase task data, for example, drugs of abuse.
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Samavat H, Ursin G, Emory TH, Lee E, Wang R, Torkelson CJ, Dostal AM, Swenson K, Le CT, Yang CS, Yu MC, Yee D, Wu AH, Yuan JM, Kurzer MS. A Randomized Controlled Trial of Green Tea Extract Supplementation and Mammographic Density in Postmenopausal Women at Increased Risk of Breast Cancer. Cancer Prev Res (Phila) 2017; 10:710-718. [PMID: 28904061 PMCID: PMC7337967 DOI: 10.1158/1940-6207.capr-17-0187] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 08/08/2017] [Accepted: 09/01/2017] [Indexed: 12/16/2022]
Abstract
Epidemiologic and animal studies suggest a protective role of green tea against breast cancer. However, the underlying mechanism is not understood. We conducted a randomized, double-blinded, placebo-controlled phase II clinical trial to investigate whether supplementation with green tea extract (GTE) modifies mammographic density (MD), as a potential mechanism, involving 1,075 healthy postmenopausal women. Women assigned to the treatment arm consumed daily 4 decaffeinated GTE capsules containing 1,315 mg total catechins, including 843 mg epigallocatechin-3-gallate (EGCG) for 12 months. A computer-assisted method (Madena) was used to assess MD in digital mammograms at baseline and month 12 time points in 932 completers (462 in GTE and 470 in placebo). GTE supplementation for 12 months did not significantly change percent MD (PMD) or absolute MD in all women. In younger women (50-55 years), GTE supplementation significantly reduced PMD by 4.40% as compared with the placebo with a 1.02% PMD increase from pre- to postintervention (P = 0.05), but had no effect in older women (Pinteraction = 0.07). GTE supplementation did not induce MD change in other subgroups of women stratified by catechol-O-methyltransferase genotype or level of body mass index. In conclusion, 1-year supplementation with a high dose of EGCG did not have a significant effect on MD measures in all women, but reduced PMD in younger women, an age-dependent effect similar to those of tamoxifen. Further investigation of the potential chemopreventive effect of green tea intake on breast cancer risk in younger women is warranted. Cancer Prev Res; 10(12); 710-8. ©2017 AACR.
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Smith TT, Cassidy RN, Tidey JW, Luo X, Le CT, Hatsukami DK, Donny EC. Impact of smoking reduced nicotine content cigarettes on sensitivity to cigarette price: further results from a multi-site clinical trial. Addiction 2017; 112:349-359. [PMID: 27741367 PMCID: PMC5233558 DOI: 10.1111/add.13636] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 06/29/2016] [Accepted: 09/27/2016] [Indexed: 01/02/2023]
Abstract
AIMS To assess the impact of a reduction in the nicotine content of cigarettes on estimated consumption of reduced nicotine cigarettes and usual brand cigarettes at a variety of hypothetical prices. DESIGN Double-blind study with participants assigned randomly to receive cigarettes for 6 weeks that were either usual brand or an investigational cigarette with one of five nicotine contents. SETTING Ten sites across the United States. PARTICIPANTS A total of 839 eligible adult smokers randomized from 2013 to 2014. INTERVENTION AND COMPARATOR Participants received their usual brand or an investigational cigarette with one of five nicotine contents: 15.8 (primary control), 5.2, 2.4, 1.3, or 0.4 mg/g. MEASUREMENTS The Cigarette Purchase Task was completed at baseline and at the week 6 post-randomization visit. FINDINGS Compared with normal nicotine content controls, the lowest nicotine content (0.4 mg/g) reduced the number of study cigarettes participants estimated they would smoke at a range of prices [mean reduction relative to 15.8 mg/g at a price of $4.00/pack: 9.50, 95% confidence interval (CI) = 6.81,12.19]. The lowest nicotine content also reduced the maximum amount of money allocated to study cigarettes and the price at which participants reported they would stop buying study cigarettes [median reduction relative to 15.8 mg/g, 95% CI = $8.21 (4.27,12.15) per day and $0.44 (0.17,0.71) per cigarette, respectively]. A reduction in nicotine content to the lowest level also reduced the maximum amount of money allocated to usual brand cigarettes (median reduction relative to 15.8 mg/g: $4.39 per day, 95% CI = 1.88,6.90). CONCLUSIONS In current smokers, a reduction in nicotine content may reduce cigarette consumption, reduce the reinforcement value of cigarettes and increase cessation if reduced nicotine content cigarettes were the only cigarette available for purchase.
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Donny EC, Denlinger RL, Tidey JW, Koopmeiners JS, Benowitz NL, Vandrey RG, al'Absi M, Carmella SG, Cinciripini PM, Dermody SS, Drobes DJ, Hecht SS, Jensen J, Lane T, Le CT, McClernon FJ, Montoya ID, Murphy SE, Robinson JD, Stitzer ML, Strasser AA, Tindle H, Hatsukami DK. Randomized Trial of Reduced-Nicotine Standards for Cigarettes. N Engl J Med 2015; 373:1340-9. [PMID: 26422724 PMCID: PMC4642683 DOI: 10.1056/nejmsa1502403] [Citation(s) in RCA: 291] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND The Food and Drug Administration can set standards that reduce the nicotine content of cigarettes. METHODS We conducted a double-blind, parallel, randomized clinical trial between June 2013 and July 2014 at 10 sites. Eligibility criteria included an age of 18 years or older, smoking of five or more cigarettes per day, and no current interest in quitting smoking. Participants were randomly assigned to smoke for 6 weeks either their usual brand of cigarettes or one of six types of investigational cigarettes, provided free. The investigational cigarettes had nicotine content ranging from 15.8 mg per gram of tobacco (typical of commercial brands) to 0.4 mg per gram. The primary outcome was the number of cigarettes smoked per day during week 6. RESULTS A total of 840 participants underwent randomization, and 780 completed the 6-week study. During week 6, the average number of cigarettes smoked per day was lower for participants randomly assigned to cigarettes containing 2.4, 1.3, or 0.4 mg of nicotine per gram of tobacco (16.5, 16.3, and 14.9 cigarettes, respectively) than for participants randomly assigned to their usual brand or to cigarettes containing 15.8 mg per gram (22.2 and 21.3 cigarettes, respectively; P<0.001). Participants assigned to cigarettes with 5.2 mg per gram smoked an average of 20.8 cigarettes per day, which did not differ significantly from the average number among those who smoked control cigarettes. Cigarettes with lower nicotine content, as compared with control cigarettes, reduced exposure to and dependence on nicotine, as well as craving during abstinence from smoking, without significantly increasing the expired carbon monoxide level or total puff volume, suggesting minimal compensation. Adverse events were generally mild and similar among groups. CONCLUSIONS In this 6-week study, reduced-nicotine cigarettes versus standard-nicotine cigarettes reduced nicotine exposure and dependence and the number of cigarettes smoked. (Funded by the National Institute on Drug Abuse and the Food and Drug Administration Center for Tobacco Products; ClinicalTrials.gov number, NCT01681875.).
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Balbo S, Johnson CS, Kovi RC, James-Yi SA, O'Sullivan MG, Wang M, Le CT, Khariwala SS, Upadhyaya P, Hecht SS. Carcinogenicity and DNA adduct formation of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and enantiomers of its metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol in F-344 rats. Carcinogenesis 2014; 35:2798-806. [PMID: 25269804 PMCID: PMC4247520 DOI: 10.1093/carcin/bgu204] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 08/19/2014] [Accepted: 08/28/2014] [Indexed: 12/28/2022] Open
Abstract
4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is metabolized to enantiomers of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), found in the urine of virtually all people exposed to tobacco products. We assessed the carcinogenicity in male F-344 rats of (R)-NNAL (5 ppm in drinking water), (S)-NNAL (5 ppm), NNK (5 ppm) and racemic NNAL (10 ppm) and analyzed DNA adduct formation in lung and pancreas of these rats after 10, 30, 50 and 70 weeks of treatment. All test compounds induced a high incidence of lung tumors, both adenomas and carcinomas. NNK and racemic NNAL were most potent; (R)-NNAL and (S)-NNAL had equivalent activity. Metastasis was observed from primary pulmonary carcinomas to the pancreas, particularly in the racemic NNAL group. DNA adducts analyzed were O (2)-[4-(3-pyridyl)-4-oxobut-1-yl]thymidine (O (2)-POB-dThd), 7-[4-(3-pyridyl)-4-oxobut-1-yl]guanine(7-POB-Gua),O (6)-[4-(3-pyridyl)-4-oxobut-1-yl]deoxyguanosine(O (6)-POB-dGuo),the 4-(3-pyridyl)-4-hydroxybut-1-yl(PHB)adductsO (2)-PHB-dThd and 7-PHB-Gua, O (6)-methylguanine (O (6)-Me-Gua) and 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB)-releasing adducts. Adduct levels significantly decreased with time in the lungs of rats treated with NNK. Pulmonary POB-DNA adducts and O (6)-Me-Gua were similar in rats treated with NNK and (S)-NNAL; both were significantly greater than in the (R)-NNAL rats. In contrast, pulmonary PHB-DNA adduct levels were greatest in the rats treated with (R)-NNAL. Total pulmonary DNA adduct levels were similar in (S)-NNAL and (R)-NNAL rats. Similar trends were observed for DNA adducts in the pancreas, but adduct levels were significantly lower than in the lung. The results of this study clearly demonstrate the potent pulmonary carcinogenicity of both enantiomers of NNAL in rats and provide important new information regarding DNA damage by these compounds in lung and pancreas.
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Zarth AT, Carmella SG, Le CT, Hecht SS. Effect of cigarette smoking on urinary 2-hydroxypropylmercapturic acid, a metabolite of propylene oxide. J Chromatogr B Analyt Technol Biomed Life Sci 2014; 953-954:126-31. [PMID: 24608133 PMCID: PMC3993985 DOI: 10.1016/j.jchromb.2014.02.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 01/30/2014] [Accepted: 02/03/2014] [Indexed: 10/25/2022]
Abstract
2-Hydroxypropylmercapturic acid (2-HPMA) is a urinary biomarker of exposure to propylene oxide, a mutagen and carcinogen to which humans are exposed through inhalation of cigarette smoke as well as in certain environmental and occupational settings. 2-HPMA is the final product of a detoxification pathway in which propylene oxide is conjugated with glutathione, and the resulting conjugate is further metabolized and excreted. We have developed and validated a liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometric (LC-APCI-MS/MS) method for the rapid quantitation of 2-HPMA in human urine. The method was applied to an analysis of urine samples from 40 smokers and 40 nonsmokers as well as from a group of 15 subjects who quit smoking. The results demonstrate that smokers have significantly (P<0.001) higher levels of urinary 2-HPMA (median=480pmol/mg creatinine) than do nonsmokers (208pmol/mg). Similarly, subjects who quit smoking for four weeks exhibited a significant (P<0.001) 52% median decrease in urinary 2-HPMA upon cessation. Approximately 5% of all urine samples had unusually high levels of 2-HPMA (>10 times higher than the median), apparently unrelated to tobacco smoke exposure or available demographic data. The method presented here can be used to rapidly quantify an individual's exposure to propylene oxide via tobacco smoke or other sources.
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Abbott AM, Portschy PR, Lee C, Le CT, Han LK, Washington T, Kinney M, Bretzke M, Tuttle TM. Prospective Multicenter Trial Evaluating Balloon-Catheter Partial-Breast Irradiation for Ductal Carcinoma in Situ. Int J Radiat Oncol Biol Phys 2013; 87:494-8. [DOI: 10.1016/j.ijrobp.2013.06.2056] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 06/10/2013] [Accepted: 06/27/2013] [Indexed: 11/29/2022]
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Balbo S, Johnson CS, Zhao L, O'Sullivan MG, Stepanov I, Wang M, Kassie F, Carmella S, Upadhyaya P, Le CT, Hecht SS. Abstract A01: Lung and pancreatic carcinogenicity and DNA binding of the enantiomers of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) in F344 rats. Cancer Prev Res (Phila) 2013. [DOI: 10.1158/1940-6215.prev-13-a01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
The tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a potent pulmonary carcinogen in laboratory animals and is believed to play an important role as a cause of tobacco related cancers. NNK is metabolically converted to NNAL in virtually all biological systems. All tobacco users as well as people exposed to secondhand tobacco smoke have NNAL in their urine. NNAL has a chiral center at its 1-position, thus consequently exists in enantiomeric forms. Previous studies have shown differing amounts of (R)- or (S)-NNAL in human tissues and urine after exposure to NNK, depending on the conditions and the system studied. However, little is known about the carcinogenic activity of (R)- or (S)-NNAL. Only one previous study has been reported demonstrating higher lung tumorigenicity of (S)-NNAL than (R)-NNAL in an A/J mouse model. Understanding mechanisms of carcinogenesis by these compounds can provide critical insights relevant for cancer prevention in people exposed to tobacco products. Therefore, in the study reported here, we have evaluated the carcinogenicity and DNA binding of the NNAL enantiomers in F-344 rats chronically treated with these compounds in the drinking water.
Groups of 24 male F-344 rats, 7 weeks of age, were treated chronically with NNK, (R)-NNAL or (S)-NNAL (5 ppm in drinking water). Controls received tap water or racemic NNAL (15 rats, 10 ppm in drinking water). The chronic treatment lasted 90 weeks. The number of animals per group which came to necropsy at the end of the study were: NNK, 23; (R)-NNAL, 23; (S)-NNAL, 22; control, 22; racemic NNAL, 15. Nearly all animals in the (R)-NNAL, (S)-NNAL, racemic NNAL, and NNK-treated groups had lung tumors. In the (R)-NNAL-treated group, there were 22 animals with lung adenoma and 3 with lung carcinoma while in the (S)-NNAL group there were 20 rats with lung adenoma and 5 with lung carcinoma. In the racemic NNAL group there were 15 rats with lung adenoma and 13 with lung carcinoma while in the NNK group there were 23 rats with lung adenoma and 14 with lung carcinoma. There were no lung tumors in the control animals. These results demonstrate that both enantiomers of NNAL are pulmonary carcinogens in the F-344 rat, but less carcinogenic to the lung than NNK (P<0.001). Tumors of the pancreas, predominantly exocrine adenocarcinomas, were also observed in this study: (R)-NNAL, 1 rat with 2 tumors; (S)-NNAL 2 rats with 3 tumors; racemic NNAL, 4 rats with 14 tumors; NNK 3 rats with 3 tumors.
DNA binding studies were performed using tissues harvested at various time-points throughout the experiment. Rats (9 per group) from the NNK, (R)-NNAL, (S)-NNAL, and control groups were euthanized at 10, 30, 50 and 70 weeks. DNA was isolated from the lung and pancreas tissues. The DNA samples were analyzed by LC-ESI-MS/MS with selected reaction monitoring (SRM) analysis for various DNA adducts. O6-Methyl-Gua, POB-DNA adducts, including 7-POB-Gua, O2-POB-dThd and O6-POB-dG and PHB-DNA adducts, including 7-PHB-Gua, O2-PHB-dThd and O6-PHB-dG were measured in lung DNA samples. POB-DNA adducts were measured in pancreas DNA. The preliminary results from these analyses indicate that O6-Methyl-Gua and POB-DNA adducts levels (both in lung and pancreas DNA) were similar in NNK and (S)-NNAL treated rats and significantly higher than in (R)-NNAL treated rats, while PHB-DNA adducts levels were significantly higher in (R)-NNAL treated animals compared to NNK and (S)-NNAL treated groups. The results of this study demonstrate that both (R)-NNAL and (S)-NNAL, at 5 ppm in the drinking water, are effective pulmonary carcinogens in the F-344 rat and are metabolically activated to DNA binding metabolites in the lung. Furthermore, the results presented here confirm the previously observed pancreatic carcinogenicity of racemic NNAL in the F-344 rat. Collectively, these results provide important new insights relevant to mechanisms of carcinogenesis by NNK and NNAL, and to lung and pancreatic cancer in people exposed to tobacco products.
Citation Format: Silvia Balbo, Charles S. Johnson, Lijiao Zhao, M Gerard O'Sullivan, Irina Stepanov, Mingyao Wang, Fekadu Kassie, Steven Carmella, Pramod Upadhyaya, Chap T. Le, Stephen S. Hecht. Lung and pancreatic carcinogenicity and DNA binding of the enantiomers of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) in F344 rats. [abstract]. In: Proceedings of the Twelfth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2013 Oct 27-30; National Harbor, MD. Philadelphia (PA): AACR; Can Prev Res 2013;6(11 Suppl): Abstract nr A01.
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Liao W, Luo X, Le CT, Chu H, Epstein LH, Yu J, Ahluwalia JS, Thomas JL. Analysis of cigarette purchase task instrument data with a left-censored mixed effects model. Exp Clin Psychopharmacol 2013; 21:124-32. [PMID: 23356731 PMCID: PMC4636201 DOI: 10.1037/a0031610] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The drug purchase task is a frequently used instrument for measuring the relative reinforcing efficacy (RRE) of a substance, a central concept in psychopharmacological research. Although a purchase task instrument, such as the cigarette purchase task (CPT), provides a comprehensive and inexpensive way to assess various aspects of a drug's RRE, the application of conventional statistical methods to data generated from such an instrument may not be adequate by simply ignoring or replacing the extra zeros or missing values in the data with arbitrary small consumption values, for example, 0.001. We applied the left-censored mixed effects model to CPT data from a smoking cessation study of college students and demonstrated its superiority over the existing methods with simulation studies. Theoretical implications of the findings, limitations of the proposed method, and future directions of research are also discussed.
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Stepanov I, Muzic J, Le CT, Sebero E, Villalta P, Ma B, Jensen J, Hatsukami D, Hecht SS. Analysis of 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB)-releasing DNA adducts in human exfoliated oral mucosa cells by liquid chromatography-electrospray ionization-tandem mass spectrometry. Chem Res Toxicol 2013; 26:37-45. [PMID: 23252610 PMCID: PMC3631465 DOI: 10.1021/tx300282k] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Quantitation of DNA adducts could provide critical information on the relationship between exposure to tobacco smoke and cancer risk in smokers. In this study, we developed a robust and sensitive liquid chromatography-tandem mass spectrometry method for the analysis of 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB)-releasing DNA adducts in human oral cells, a noninvasive source of DNA for biomarker studies. Isolated DNA undergoes acid hydrolysis, after which samples are purified by solid-phase extraction and analyzed by LC-ESI-MS/MS. The developed method was applied to the analysis of samples obtained via collection with a commercial mouthwash from 30 smokers and 15 nonsmokers. In smokers, the levels of HPB-releasing DNA adducts averaged 12.0 pmol HPB/mg DNA (detected in 20 out of 28 samples with quantifiable DNA yield), and in nonsmokers, the levels of adducts averaged 0.23 pmol/mg DNA (detected in 3 out of 15 samples). For the 30 smoking subjects, matching buccal brushings were also analyzed, and HPB-releasing DNA adducts were detected in 24 out of 27 samples with quantifiable DNA yield, averaging 44.7 pmol HPB/mg DNA. The levels of adducts in buccal brushings correlated with those in mouthwash samples of smokers (R = 0.73, p < 0.0001). Potentially, the method can be applied in studies of individual susceptibility to tobacco-induced cancers in humans.
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Fujioka N, Zhong Y, Holchalter JB, Rauch D, Jensen JJ, Le CT, Hatsukami DK, Hecht SS. Abstract A69: Pilot study of the effects of indole-3-carbinol on deuterated phenanthrene metabolism in smokers. Cancer Prev Res (Phila) 2012. [DOI: 10.1158/1940-6207.prev-12-a69] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Background/Purpose: Polycyclic aromatic hydrocarbons (PAH), widely considered as critical causative agents of tobacco-related lung cancer, are found in high levels in tobacco smoke and require metabolic activation to exert their carcinogenic effects. The development of urinary biomarkers of PAH metabolism using the more abundant and generally non-carcinogenic phenanthrene (Phe) as a surrogate of the prototypic carcinogenic PAH benzo[a]pyrene (BaP) has provided a reliable tool to characterize the uptake and metabolism of BaP in smokers. There is wide inter-individual variation in PheT metabolism. Furthermore, smokers who are more efficient metabolic activators of Phe appear to have a higher risk of developing lung cancer in prospective case-control studies. We examined the effects of indole-3-carbinol (I3C), a compound arising from cruciferous vegetables shown to possess anti-cancer activity, in modifying Phe metabolism. We hypothesized that I3C might have a chemopreventive effect in cigarette smokers by abrogating the metabolic activation and/or detoxification of [D10]Phe.
Procedures: Ten micrograms of [D10]Phe was administered via inhalation of a smoked cigarette prior to and after 7 days if I3C 400 mg po BID. Plasma and urine samples were collected at baseline and for 48 hours following [D10]Phe administration. Deuterated phenanthrene tetraol ([D10]PheT, a reflection of uptake and metabolic activation via the diol epoxide pathway), and deuterated phenanthrol ([D10]HOPhe, a reflection of detoxification and elimination) were quantified in urine and plasma before and after I3C and compared.
Results: A total of 8 subjects completed the study procedures, 6 females and 2 males. Subject 8 was clearly an outlier and was excluded from analysis. One-sample t-test was used to compare the mean difference in [D10]PheT and the mean difference in [D10]HOPhe among the group before and after I3C. The reduction in [D10]PheT in urine was significant (one-sample t-test, p=.023), although only marginally so in plasma (=.083). [D10]PheT AUC was not reduced (p=.23). [D10]HOPhe was generally reduced but not significantly (p=.15). Correlation between 6-hour and 48-hour [D10]PheT and [D10]HOPhe was very strong (r=.873; p=.010 and r=.968;p<.001, respectively).
Conclusion: I3C may be an effective chemopreventive agent in tobacco-related lung cancer by reducing the metabolic activation of carcinogenic PAH. A larger, definitive study is needed to confirm these results.
Citation Format: Naomi Fujioka, Yan Zhong, J. Bradley Holchalter, Diane Rauch, Joni J. Jensen, Chap T. Le, Dorothy K. Hatsukami, Stephen S. Hecht. Pilot study of the effects of indole-3-carbinol on deuterated phenanthrene metabolism in smokers. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr A69.
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Williams BW, Chang JJ, Chi RM, Marker PH, Frethem CD, Le CT, Kratzke RA, Kirstein MN. Cap-dependent translation blockade and fixed dose-rate gemcitabine: interaction in an in vitro bioreactor system. Cancer Lett 2009; 284:37-46. [PMID: 19442436 DOI: 10.1016/j.canlet.2009.04.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2008] [Revised: 04/02/2009] [Accepted: 04/03/2009] [Indexed: 01/13/2023]
Abstract
Translation initiation commences with the binding of eIF-4F to the mRNA 5'-end cap. eIF-4F binds the cap structure via its eIF-4E subunit, which is the rate-limiting step for the initiation of translation. This pathway can be inhibited by 4E-binding proteins (4E-BPs). The present study investigated prolonged gemcitabine infusion in combination with reduced eIF-4E function on NSCLC cell viability in an in vitro bioreactor system. To assess attachment to the hollow fibers, cells with dominant active 4E-BP1 were first analyzed by scanning electron microscopy. Cells were treated with 0.5- or 2.5h (fixed dose rate) infusion (same total dose), simulating human plasma gemcitabine concentration-time profiles. An interaction was observed between fixed dose rate infusion gemcitabine and presence of dominant active 4E-BP1. We conclude that cap-dependent translation blockade and fixed dose rate infusion gemcitabine treatment results in a significant interaction affecting cell viability in vitro.
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Church TR, Anderson KE, Caporaso NE, Geisser MS, Le CT, Zhang Y, Benoit AR, Carmella SG, Hecht SS. A prospectively measured serum biomarker for a tobacco-specific carcinogen and lung cancer in smokers. Cancer Epidemiol Biomarkers Prev 2009; 18:260-6. [PMID: 19124507 PMCID: PMC3513324 DOI: 10.1158/1055-9965.epi-08-0718] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND No prior studies have related a tobacco-specific carcinogen to the risk of lung cancer in smokers. Of the over 60 known carcinogens in cigarette smoke, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is specific to tobacco and causes lung cancer in laboratory animals. Its metabolites, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and its glucuronides (total NNAL), have been studied as biomarkers of exposure to NNK. We studied the relation of prospectively measured NNK biomarkers to lung cancer risk. METHODS In a case-control study nested in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, we randomly selected 100 lung cancer cases and 100 controls who smoked at baseline and analyzed their baseline serum for total NNAL, cotinine, and r-1,t-2,3,c-4-tetrahydroxy-1,2,3,4-tetrahydrophenanthrene (PheT), a biomarker of polycyclic aromatic hydrocarbon exposure and metabolic activation. To examine the association of the biomarkers with all lung cancers and for histologic subtypes, we computed odds ratios for total NNAL, PheT, and cotinine using logistic regression to adjust for potential confounders. FINDINGS Individual associations of age, smoking duration, and total NNAL with lung cancer risk were statistically significant. After adjustment, total NNAL was the only biomarker significantly associated with risk (odds ratio, 1.57 per unit SD increase; 95% confidence interval, 1.08-2.28). A similar statistically significant result was obtained for adenocarcinoma risk, but not for nonadenocarcinoma. CONCLUSIONS This first reporting of the effect of the prospectively measured tobacco-specific biomarker total NNAL, on risk of lung cancer in smokers provides insight into the etiology of smoking-related lung cancer and reinforces targeting NNK for cancer prevention.
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