Cytochrome P450 2C9 variants influence response to celecoxib for prevention of colorectal adenoma

Role of Cytochrome P450 2C9 in COVID-19 Treatment: Current Status and Future Directions

The major human liver drug metabolising cytochrome P450 (CYP) enzymes are downregulated during inflammation and infectious disease state, especially during coronavirus disease 2019 (COVID-19) infection. The influx of proinflammatory cytokines, known as a 'cytokine storm', during severe COVID-19 leads to the downregulation of CYPs and triggers new cytokine release, which further dampens CYP expression. Impaired drug metabolism, along with the inevitable co-administration of drugs or 'combination therapy' in patients with COVID-19 with various comorbidities, could cause drug-drug interactions, thus worsening the disease condition. Genetic variability or polymorphism in CYP2C9 across different ethnicities could contribute to COVID-19 susceptibility. A number of drugs used in patients with COVID-19 are inducers or inhibitors of, or are metabolised by, CYP2C9, and co-administration might cause pharmacokinetic and pharmacodynamic interactions. It is also worth mentioning that some of the COVID-19 drug interactions are due to altered activity of other CYPs including CYP3A4. Isoniazid/rifampin for COVID-19 and tuberculosis co-infection; lopinavir/ritonavir and cobicistat/remdesivir combination therapy; or multi-drug therapy including ivermectin, azithromycin, montelukast and acetylsalicylic acid, known as TNR4 therapy, all improved recovery in patients with COVID-19. However, a combination of CYP2C9 inducers, inhibitors or both, and plausibly different CYP isoforms could lead to treatment failure, hepatotoxicity or serious side effects including thromboembolism or bleeding, as observed in the combined use of azithromycin/warfarin. Further, herbs that are CYP2C9 inducers and inhibitors, showed anti-COVID-19 properties, and in silico predictions postulated that phytochemical compounds could inhibit SARS-CoV-2 virus particles. COVID-19 vaccines elicit immune responses that activate cytokine release, which in turn suppresses CYP expression that could be the source of compromised CYP2C9 drug metabolism and the subsequent drug-drug interaction. Future studies are recommended to determine CYP regulation in COVID-19, while recognising the involvement of CYP2C9 and possibly utilising CYP2C9 as a target gene to tackle the ever-mutating SARS-CoV-2.

Colorectal Cancer Chemoprevention: A Dream Coming True?

Colorectal cancer (CRC) is one of the deadliest forms of cancer worldwide. CRC development occurs mainly through the adenoma-carcinoma sequence, which can last decades, giving the opportunity for primary prevention and early detection. CRC prevention involves different approaches, ranging from fecal occult blood testing and colonoscopy screening to chemoprevention. In this review, we discuss the main findings gathered in the field of CRC chemoprevention, focusing on different target populations and on various precancerous lesions that can be used as efficacy evaluation endpoints for chemoprevention. The ideal chemopreventive agent should be well tolerated and easy to administer, with low side effects. Moreover, it should be readily available at a low cost. These properties are crucial because these compounds are meant to be used for a long time in populations with different CRC risk profiles. Several agents have been investigated so far, some of which are currently used in clinical practice. However, further investigation is needed to devise a comprehensive and effective chemoprevention strategy for CRC.

Targeting cancer-related inflammation with non-steroidal anti-inflammatory drugs: Perspectives in pharmacogenomics

Inflammatory processes are essential for innate immunity and contribute to carcinogenesis in various malignancies, such as colorectal cancer, esophageal cancer and lung cancer. Pharmacotherapies targeting inflammation have the potential to reduce the risk of carcinogenesis and improve therapeutic efficacy of existing anti-cancer treatment. Non-steroidal anti-inflammatory drugs (NSAIDs), comprising a variety of structurally different chemicals that can inhibit cyclooxygenase (COX) enzymes and other COX-independent pathways, are originally used to treat inflammatory diseases, but their preventive and therapeutic potential for cancers have also attracted researchers' attention. Pharmacogenomic variability, including distinct genetic characteristics among different patients, can significantly affect pharmacokinetics and effectiveness of NSAIDs, which might determine the preventive or therapeutic success for cancer patients. Hence, a more comprehensive understanding in pharmacogenomic characteristics of NSAIDs and cancer-related inflammation would provide new insights into this appealing strategy. In this review, the up-to-date advances in clinical and experimental researches targeting cancer-related inflammation with NSAIDs are presented, and the potential of pharmacogenomics are discussed as well.

The Importance of Drug Concentration at the Site of Action: Celecoxib and Colon Polyp Prevention as a Case Study

Celecoxib is among the more potent and better clinically studied, nonsteroidal anti-inflammatory drugs (NSAID) for use as a chemoprevention agent for colorectal cancer. Its use is associated with a 40% to 50% response rate for reduction in adenomatous polyps. However, rare serious cardiovascular effects and even death with celecoxib and other NSAIDs make it important to understand why some patients respond and others do not. Celecoxib is a selective inhibitor of COX-2. Its anticancer mechanism has largely been attributed to the inhibition of COX-2. Celecoxib also shows activity to induce apoptosis in cancer cells not expressing COX-2. This includes activity to upregulate 15-lipoxygenase-1 (15-LOX-1) independent of COX-2 and increase the synthesis of 13-S-hydroxyoctadecadienoic acid (13-S-HODE) from linoleic acid (LA) to downregulate PPAR-δ and induce apoptosis in colorectal cancer models. In examining the effect of celecoxib on 15-LOX-1 for reducing adenomatous polyps in patients with familial adenomatous polyposis (FAP), Yang and colleagues point out the potential importance of drug bioavailability in blood, normal, and neoplastic colorectal tissue in patient response. See related article, p. 217.

The Role of Cytochrome P450 Enzymes in COVID-19 Pathogenesis and Therapy

Coronavirus disease 2019 (COVID-19) has become a new public health crisis threatening the world. Dysregulated immune responses are the most striking pathophysiological features of patients with severe COVID-19, which can result in multiple-organ failure and death. The cytochrome P450 (CYP) system is the most important drug metabolizing enzyme family, which plays a significant role in the metabolism of endogenous or exogenous substances. Endogenous CYPs participate in the biosynthesis or catabolism of endogenous substances, including steroids, vitamins, eicosanoids, and fatty acids, whilst xenobiotic CYPs are associated with the metabolism of environmental toxins, drugs, and carcinogens. CYP expression and activity are greatly affected by immune response. However, changes in CYP expression and/or function in COVID-19 and their impact on COVID-19 pathophysiology and the metabolism of therapeutic agents in COVID-19, remain unclear. In this analysis, we review current evidence predominantly in the following areas: firstly, the possible changes in CYP expression and/or function in COVID-19; secondly, the effects of CYPs on the metabolism of arachidonic acid, vitamins, and steroid hormones in COVID-19; and thirdly, the effects of CYPs on the metabolism of therapeutic COVID-19 drugs.

Celecoxib Colorectal Bioavailability and Chemopreventive Response in Patients with Familial Adenomatous Polyposis

Why celecoxib exerts chemopreventive activity in only some familial adenomatous polyposis (FAP) patients remains poorly understood. We conducted a phase II clinical study to identify potential predictive biomarkers for celecoxib chemopreventive activity in FAP. Twenty-seven patients with FAP completed a 6-month oral course of 400 mg of celecoxib twice a day; they underwent colonoscopies before and after celecoxib treatment to assess colorectal polyp tumor burden and to obtain normal and polyp colorectal biopsies to measure celecoxib, 13-S-hydroxyoctadecadienoic acid (13-HODE), 15-HETE, 12-HETE, and LTB4 levels by LC/MS-MS. Celecoxib levels in sera from those patients were also measured before treatment and after 2, 4, and 6 months of treatment. Nineteen of the 27 patients experienced a response to celecoxib, with a ≥ 28% reduction of colonic polyp burden on the basis of a reproducible quantitative assessment of colonoscopy results. Celecoxib levels were significantly lower in polyp tissues than in normal colorectal tissues. Celecoxib levels in sera and normal colorectal tissues were correlated in patients who experienced a response to celecoxib but not in those who did not. Among the measured lipoxygenase products, only 13-HODE levels were significantly lower in polyp tissues than in normal tissues. Our findings demonstrate the differential bioavailability of celecoxib between normal and polyp tissues and its potential effects on clinical response in patients with FAP. PREVENTION RELEVANCE: This study evaluated potential predictive biomarkers for celecoxib chemopreventive activity in patients with FAP. Our findings demonstrated the differential bioavailability of celecoxib between normal and polyp tissues and its potential effects on clinical chemopreventive response in patients with FAP.

An update on the pharmacogenomics of NSAID metabolism and the risk of gastrointestinal bleeding

Introduction: Several reports suggest a possible association between polymorphisms in the cytochrome P450 2C9 (CYP2C9) gene and the risk for non-steroidal anti-inflammatory drug (NSAID)-related adverse gastrointestinal events, including gastrointestinal bleeding. Because findings were controversial, a systematic review and a meta-analysis of eligible studies on this putative association was conducted.Areas covered: The authors have revised the relationship between CYP2C9 polymorphisms and the risk of developing NSAID-related gastrointestinal bleeding, as well as other adverse gastrointestinal events, and performed meta-analyzes. The bias effect and potential sources of heterogeneity between studies was analyzed.Expert opinion: Individuals classified as poor metabolizers after CYP2C9 genotyping (activity scores equal to 0 or 0.5) have an increased risk of developing NSAID-related gastrointestinal adverse events with an odds ratio (OR) = 1.86, (p = 0.004) and the OR for subjects with gastrointestinal bleeding is = 1.90, (p = 0.003). Gene-dose effect for variant CYP2C9 alleles (p = 0.005 for all gastrointestinal adverse events, and p = 0.0001 for bleeding patients) was observed. Also, there is an allele-specific effect in the association: CYP2C9*2 is a poor risk predictor, whereas CYP2C9*3 is a highly significant predictor of gastrointestinal adverse events (p = 0.006) and gastrointestinal bleeding (p = 0.0007).

Genomics Testing and Personalized Medicine in the Preoperative Setting

Pharmacogenomics (PGx) is the study of how individuals' personal genotypes may affect their responses to various pharmacologic agents. The application of PGx principles in perioperative medicine is fairly novel. Challenges in executing PGx programs into health care systems include physician buy-in and integration into usual clinical workflow, including the electronic health record. This article discusses the current evidence highlighting the potential of PGx with various drug categories (including opioids, nonopioid analgesics, sedatives, β-blockers, antiemetics, and anticoagulants) used in the perioperative process and the challenges of integrating PGx into a health care system and relevant workflows.

The Cytochrome P450 Slow Metabolizers CYP2C9*2 and CYP2C9*3 Directly Regulate Tumorigenesis via Reduced Epoxyeicosatrienoic Acid Production

Increased expression of cytochrome P450 CYP2C9, together with elevated levels of its products epoxyeicosatrienoic acids (EET), is associated with aggressiveness in cancer. Cytochrome P450 variants CYP2C9*2 and CYP2C9*3 encode proteins with reduced enzymatic activity, and individuals carrying these variants metabolize drugs more slowly than individuals with wild-type CYP2C9*1, potentially affecting their response to drugs and altering their risk of disease. Although genetic differences in CYP2C9-dependent oxidation of arachidonic acid (AA) have been reported, the roles of CYP2C9*2 and CYP2C9*3 in EET biosynthesis and their relevance to disease are unknown. Here, we report that CYP2C9*2 and CYP2C9*3 metabolize AA less efficiently than CYP2C9*1 and that they play a role in the progression of non-small cell lung cancer (NSCLC) via impaired EET biosynthesis. When injected into mice, NSCLC cells expressing CYP2C9*2 and CYP2C9*3 produced lower levels of EETs and developed fewer, smaller, and less vascularized tumors than cells expressing CYP2C9*1. Moreover, endothelial cells expressing these two variants proliferated and migrated less than cells expressing CYP2C*1. Purified CYP2C9*2 and CYP2C9*3 exhibited attenuated catalytic efficiency in producing EETs, primarily due to impaired reduction of these two variants by NADPH-P450 reductase. Loss-of-function SNPs within CYP2C9*2 and CYP2C9*3 were associated with improved survival in female cases of NSCLC. Thus, decreased EET biosynthesis represents a novel mechanism whereby CYPC29*2 and CYP2C9*3 exert a direct protective role in NSCLC development.Significance: These findings report single nucleotide polymorphisms in the human CYP2C9 genes, CYP2C9*2 and CYP2C9*3, exert a direct protective role in tumorigenesis by impairing EET biosynthesis. Cancer Res; 78(17); 4865-77. ©2018 AACR.

The cytochrome P450 isoenzyme and some new opportunities for the prediction of negative drug interaction in vivo

Cytochrome (CYP) 450 isoenzymes are the basic enzymes involved in Phase I biotransformation. The most important role in biotransformation belongs to CYP3A4, CYP2D6, CYP2C9, CYP2C19 and CYP1A2. Inhibition and induction of CYP isoenzymes caused by drugs are important and clinically relevant pharmacokinetic mechanisms of drug interaction. Investigation of the activity of CYP isoenzymes by using phenotyping methods (such as the determination of the concentration of specific substrates and metabolites in biological fluids) during drug administration provides the prediction of negative side effects caused by drug interaction. In clinical practice, the process of phenotyping of CYP isoenzymes and some endogenous substrates in the ratio of cortisol to 6β-hydroxycortisol in urine for the evaluation of CYP3A4 activity has been deemed to be a quite promising, safe and minimally invasive method for patients nowadays.

Celecoxib-induced Liver Injury: Analysis of Published Case Reports and Cases Reported to the Food and Drug Administration

BACKGROUND

Celecoxib is a widely prescribed nonsteroidal anti-inflammatory drug, and has been associated with rare instances of idiosyncratic drug-induced liver injury (DILI). The aim of this study is to describe and analyze the salient features of published cases of celecoxib DILI.

MATERIALS AND METHODS

A literature search using common terms for liver injury cross-referenced with celecoxib was undertaken from the year 2000 through June 2016. Identified cases were analyzed with respect to reported demographic and clinical data with descriptive.

RESULTS

Celecoxib DILI was reported in 18 patients with a median age of 54 years (range, 29 to 84) and 15 (88%) were female. The median daily dose was 200 mg (range, 200 to 533), and median duration and latency were 13 days (1 to 730) and 17 days (2 to 730), respectively. In 15 (83%) cases, DILI occurred after relatively short treatment duration, median of 12 days (1 to 42). Rash and immunoallergic features were noted in these patients, with peripheral or histologic findings of eosinophilia in 6 (40%). In 3 cases, DILI occurred after prolonged exposure (range, 152 to 730 d), none with immunoallergic features. The pattern of liver injury included hepatocellular (6), mixed (5), and cholestatic (4), and was unknown in 3 cases. Clinical outcomes included 2 (11%) requiring liver transplantation, 4 (22%) with chronic liver injury and recovery in 12 (67%) cases.

CONCLUSIONS

Women are overrepresented in published reports of celecoxib DILI. Latency was short (<3 mo) in most patients but some subjects may present with DILI following prolonged celecoxib use. Although rare, celecoxib-DILI can have potentially life threatening consequences.

Pharmacogenomics of CYP2C9: Functional and Clinical Considerations

CYP2C9 is the most abundant CYP2C subfamily enzyme in human liver and the most important contributor from this subfamily to drug metabolism. Polymorphisms resulting in decreased enzyme activity are common in the CYP2C9 gene and this, combined with narrow therapeutic indices for several key drug substrates, results in some important issues relating to drug safety and efficacy. CYP2C9 substrate selectivity is detailed and, based on crystal structures for the enzyme, we describe how CYP2C9 catalyzes these reactions. Factors relevant to clinical response to CYP2C9 substrates including inhibition, induction and genetic polymorphism are discussed in detail. In particular, we consider the issue of ethnic variation in pattern and frequency of genetic polymorphisms and clinical implications. Warfarin is the most well studied CYP2C9 substrate; recent work on use of dosing algorithms that include CYP2C9 genotype to improve patient safety during initiation of warfarin dosing are reviewed and prospects for their clinical implementation considered. Finally, we discuss a novel approach to cataloging the functional capabilities of rare 'variants of uncertain significance', which are increasingly detected as more exome and genome sequencing of diverse populations is conducted.

Aspirin and colorectal cancer: the promise of precision chemoprevention

Aspirin (acetylsalicylic acid) has become one of the most commonly used drugs, given its role as an analgesic, antipyretic and agent for cardiovascular prophylaxis. Several decades of research have provided considerable evidence demonstrating its potential for the prevention of cancer, particularly colorectal cancer. Broader clinical recommendations for aspirin-based chemoprevention strategies have recently been established; however, given the known hazards of long-term aspirin use, larger-scale adoption of an aspirin chemoprevention strategy is likely to require improved identification of individuals for whom the protective benefits outweigh the harms. Such a precision medicine approach may emerge through further clarification of aspirin's mechanism of action.

Simultaneous quantitative determination of celecoxib and its two metabolites using liquid chromatography-tandem mass spectrometry in alternating polarity switching mode

A simple and rapid quantitative analytical method for the simultaneous detection of celecoxib and its two main metabolites, hydroxycelecoxib (celecoxib-OH) and celecoxib carboxylic acid (celecoxib-COOH), in rat plasma using liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. The plasma sample was prepared through simple protein precipitation, and the reconstitution solution (0.1% formic acid in 50% methanol) was optimized to achieve the best peak shape and recovery. The analytes were separated using an Atlantis T3 column (2.1 mm × 100 mm, 3 μm), and the mobile phase was composed of 10 mM ammonium formate in either 5% acetonitrile or 95% acetonitrile. The detection of the analytes was performed in alternating polarity switching mode using electrospray ionization. As celecoxib-OH and celecoxib-COOH were slightly unstable following freeze-thaw cycles and long-term storage at -80°C in stability tests, every analysis was carefully conducted with one-freeze thaw cycle and a short storage duration (<1 week). Acceptable accuracy (<15%) and precision (<15%) were obtained in intra- and inter-day validations. The method was successfully applied to the pharmacokinetic study of celecoxib, celecoxib-OH and celecoxib-COOH following the oral administration of celecoxib in rats at a dose of 10mg/kg. Comparing the related pharmacokinetic parameters of celecoxib and its metabolites, celecoxib was quickly metabolized into celecoxib-OH and subsequently converted to celecoxib-COOH in short intervals. The AUCs for the two metabolites were less than 10% of that for celecoxib, indicating that the rate of celecoxib metabolism was low.

Liposomal gels for site-specific, sustained delivery of celecoxib: in vitro and in vivo evaluation

The objective of this work was to evaluate liposome-containing gel formulations for the sustained, site-specific delivery of celecoxib (CXB). Liposomes composed of phosphadtidylcholine (and various amounts of cholesterol (Ch) were prepared using thin film hydration and characterized for encapsulation efficiency, vesicle size, and drug-excipient interaction using differential scanning calorimetry and Fourier-transform infrared spectroscopy. The selected liposome formulation was incorporated in different gel formulations: the Ch ratio affected the encapsulation efficiency of the drug, by increasing Ch ratio up until 1:1 the encapsulation efficiency increased. Further increasing the Ch ratio resulted in decreasing encapsulation efficiency. In vitro drug release and skin permeation studies showed sustained release and enhanced permeation compared with gel formulations containing free drug. In the rat paw edema test, the anti-inflammatory activity of the selected liposomal gel formulation was higher and more sustained compared with that of the nonliposomal gel formulation containing free drug. These results suggest that the liposome-containing gels are promising formulations for sustained, site-specific delivery of CXB.

The influence of Cox-2 and bioactive lipids on hematological cancers

Inflammation is implicated in the progression of multiple types of cancers including lung, colorectal, breast and hematological malignancies. Cyclooxygenases (Cox) -1 and -2 are important enzymes involved in the regulation of inflammation. Elevated Cox-2 expression is associated with a poor cancer prognosis. Hematological malignancies, which are among the top 10 most predominant cancers in the USA, express high levels of Cox-2. Current therapeutic approaches against hematological malignances are insufficient as many patients develop resistance or relapse. Therefore, targeting Cox-2 holds promise as a therapeutic approach to treat hematological malignancies. NSAIDs and Cox-2 selective inhibitors are anti-inflammatory drugs that decrease prostaglandin and thromboxane production while promoting the synthesis of specialized proresolving mediators. Here, we review the evidence regarding the applicability of NSAIDs, such as aspirin, as well as Cox-2 specific inhibitors, to treat hematological malignancies. Furthermore, we discuss how FDA-approved Cox inhibitors can be used as anti-cancer drugs alone or in combination with existing chemotherapeutic treatments.

Prediction of survival in resected non-small cell lung cancer using a protein expression-based risk model: implications for personalized chemoprevention and therapy

PURPOSE

Patients with resected non-small cell lung cancer (NSCLC) are at risk for recurrence of disease, but we do not have tools to predict which patients are at highest risk. We set out to create a risk model incorporating both clinical data and biomarkers.

EXPERIMENTAL DESIGN

We assembled a comprehensive database with archival tissues and clinical follow-up from patients with NSCLC resected between 2002 and 2005. Twenty-one proteins identified from our preclinical studies as related to lung carcinogenesis were investigated, including pathways related to metabolism, DNA repair, inflammation, and growth factors. Expression of proteins was quantified using immunohistochemistry. Immunohistochemistry was chosen because it is widely available and can be performed on formalin-fixed paraffin-embedded specimens. Cox models were fitted to estimate effects of clinical factors and biomarkers on recurrence-free survival (RFS) and overall survival (OS).

RESULTS

A total of 370 patients are included in our analysis. With median follow-up of 5.3 years, median OS is 6.4 years. A total of 209 cases with recurrence or death were observed. Multicovariate risk models for RFS and OS were developed including relevant biomarkers, age, and stage. Increased expression of phospho-adenosine monophosphate-activated protein kinase (pAMPK), phospho-mTOR (pmTOR), epithelial cell adhesion molecule (EpCAM), and calcium/calmodulin-dependent serine protein kinase were significant (P < 0.05) predictors for favorable RFS; insulin receptor, chemokine (C-X-C motif) receptor 2 (CXCR2), and insulin-like growth factor-1 receptor predicted for unfavorable RFS. Significant (P < 0.05) predictors for favorable OS include pAMPK, pmTOR, and EpCAM; CXCR2 and flap structure-specific endonuclease-1 predicted unfavorable OS.

CONCLUSION

We have developed a comprehensive risk model predictive for recurrence in our large retrospective database, which is one of the largest reported series of resected NSCLC.

Pharmacogenomics of acetylsalicylic acid and other nonsteroidal anti-inflammatory agents: clinical implications

PURPOSE

Pharmacogenomics investigates interindividual genetic variability in the DNA sequence of drug targets, drug-metabolizing enzymes or disease genes, RNA expression, or protein translation of genes affecting drug response and drug safety. Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most commonly prescribed medications with well-documented variation in patient response in terms of efficacy and safety. This variation may in part be explained by pharmacogenomics.

METHODS

In this paper I review data on the pharmacogenomics of aspirin and other NSAIDs focusing on clinical implications.

RESULTS

Existing scientific evidence supports the pharmacogenomic basis of interindividual variation in treatment response to aspirin and NSAIDs, with clinical implications for antiplatelet action, cancer chemoprevention, and drug safety. However, further research efforts are needed before knowledge on the pharmacogenomics of aspirin and NSAIDs can be implemented in clinical practice.

CONCLUSION

The outcome of these research efforts would be anticipated to have added value for both science and society, contributing to the enhanced efficacy and safety of these agents through patient selection.

Analysis of the Functional Polymorphism in the Cytochrome P450 CYP2C8 Gene rs11572080 with Regard to Colorectal Cancer Risk

In addition to the known effects on drug metabolism and response, functional polymorphisms of genes coding for xenobiotic-metabolizing enzymes (XME) play a role in cancer. Genes coding for XME act as low-penetrance genes and confer modest but consistent and significant risks for a variety of cancers related to the interaction of environmental and genetic factors. Consistent evidence supports a role for polymorphisms of the cytochrome P450 CYP2C9 gene as a protecting factor for colorectal cancer susceptibility. It has been shown that CYP2C8 and CYP2C9 overlap in substrate specificity. Because CYP2C8 has the common functional polymorphisms rs11572080 and rs10509681 (CYP2C8*3), it could be speculated that part of the findings attributed to CYP2C9 polymorphisms may actually be related to the presence of polymorphisms in the CYP2C8 gene. Nevertheless, little attention has been paid to the role of the CYP2C8 polymorphism in colorectal cancer. We analyzed the influence of the CYP2C8*3 allele in the risk of developing colorectal cancer in genomic DNA from 153 individuals suffering colorectal cancer and from 298 age- and gender-matched control subjects. Our findings do not support any effect of the CYP2C8*3 allele (OR for carriers of functional CYP2C8 alleles = 0.50 (95% CI = 0.16–1.59; p = 0.233). The absence of a relative risk related to CYP2C8*3 did not vary depending on the tumor site. We conclude that the risk of developing colorectal cancer does not seem to be related to the commonest functional genetic variation in the CYP2C8 gene.

CYP2C9 variants increase risk of colorectal adenoma recurrence and modify associations with smoking but not aspirin treatment

PURPOSE

The cytochrome P450 2C9 enzyme (CYP2C9) is involved in metabolism of endogenous compounds, drugs, and procarcinogens. Two common nonsynonymous polymorphisms in CYP2C9 are associated with reduced enzyme activity: CYP2C9*2 (rs1799853, R144C) and CYP2C9*3 (rs1057910, I359L).

METHODS

We investigated whether CYP2C9 genotype was associated with risk of colorectal adenoma and/or modified associations with aspirin treatment or cigarette smoking in a cohort of 928 participants in a randomized trial of aspirin chemoprevention. Generalized linear regression was used to compute relative risks (RRs) and 95 % confidence intervals (95 % CIs). Multiplicative interactions terms were used to assess effect modification.

RESULTS

CYP2C9 genotype was associated with increased risks for adenoma recurrence of 29 % (RR = 1.29, 95 % CI 1.09-1.51) for ≥1 variant allele (CYP2C9*2 or *3) and 47 % (RR = 1.47, 95 % CI 1.19-1.83) for ≥1 CYP2C9*3 allele. The risk for advanced lesions or multiple (≥3) adenomas was increased by 64 % (RR = 1.64, 95 % CI 1.18-2.28) for ≥1 variant allele (CYP2C9*2 or *3) and 79 % (RR = 1.79, 95 % CI 1.16-2.75) for ≥1 CYP2C9*3 allele. Genotype modified associations with smoking, but not aspirin treatment. The adenoma risk was increased by 26 % (RR = 1.26, 95 % CI 0.99-1.58) for former smokers and 60 % (RR = 1.60, 95 % CI 1.19-2.15) for current smokers among wild-type individuals, but there was no increased risk among individuals with ≥1 variant allele (CYP2C9*2 or *3) (p (interaction) = 0.04).

CONCLUSIONS

Carriers of CYP2C9 variants with lower enzyme activity have increased overall risk of colorectal adenoma but reduced adenoma risk associated with cigarette smoking. These results may be due to effects on the synthesis of endogenous eicosanoids and/or reduced activation of procarcinogens in smoke by CYP2C9 variants.

Pharmacogenetics of nonsteroidal anti-inflammatory drugs

With the beginning of the Human Genome Project, an emerging field of science was brought to the forefront of the pharmaceutical community. Pharmacogenetics facilitates optimization of the current patient-centered care model and pharmacotherapy as a whole. Utilizing these ever-expanding branches of science to nonsteroidal anti-inflammatory drugs (NSAIDs) can provide novel opportunities to affect patient care. With a wide range of NSAID choices available as treatment options for relieving pain and/or reducing inflammation or fever, a more systematic way of selecting the ideal agent for the patients based upon their genetic information could spare them from a potentially permanent health-care condition. Furthermore, if a patient possesses or lacks certain alleles, serious adverse events can be anticipated and avoided. The tailoring of drug therapy can be achieved using the published data and cutting-edge genetic testing to attain a higher standard of care for patients.

In vivo optical molecular imaging of matrix metalloproteinase activity following celecoxib therapy for colorectal cancer

We present an optical molecular imaging approach to measure the efficacy of the cyclooxygenase-2 (COX-2) inhibitor celecoxib on tumor growth rate through its effect on matrix metalloproteinase (MMP) activity. A xenograft model of colorectal cancer was generated in nude mice, which were then randomized to receive celecoxib versus vehicle. MMP activity was measured by an enzyme-activatable optical molecular probe. A novel genetically engineered mouse (GEM) model of colorectal cancer was also used to assess celecoxib's effect on MMP activity, which was measured by quantitative fluorescence colonoscopy. Subcutaneously implanted xenograft tumors were 84% (SD 20.2%) smaller in volume in the treatment group versus the control group. Moreover, treated animals exhibited only a 7.6% (SEM 9%) increase in MMP activity versus 106% (SEM 8%) for untreated animals. There was an apparent linear relationship (r  =  .91) between measured MMP activity and tumor growth rate. Finally, in the GEM model experiment, treated murine tumors remained relatively unchanged in volume and MMP activity; however, untreated tumors grew significantly and showed an increase in MMP activity. This method may provide for the improved identification of patients for whom COX-2 inhibition therapy is indicated by allowing one to balance the patient's cardiovascular risk with the cancer's responsiveness to celecoxib.

The influence of UGT1A6 variants and aspirin use in a randomized trial of celecoxib for prevention of colorectal adenoma

Aspirin and celecoxib prevent colorectal adenoma recurrence. Genetic variants in the UGT1A6 enzyme are associated with delayed aspirin metabolism and greater chemopreventive efficacy. We examined the effect of combining aspirin and celecoxib in relation to UGT1A6 T181A and R184S variants among 1,647 patients in the Adenoma Prevention with Celecoxib (APC) trial who were stratified according to the use of low-dose aspirin after removal of adenomas and randomized to placebo, 200-mg twice daily, or 400-mg twice daily celecoxib for 3 years. Patients underwent follow-up colonoscopies at 1 and 3 years to assess on-treatment efficacy. At 5 years, 538 patients underwent a colonoscopy to assess risk of recurrence after treatment was discontinued for at least 1 year. During treatment, the relative risk (RR) of recurrent adenoma was 0.68 [95% confidence interval (CI), 0.59-0.79] for 200-mg twice daily celecoxib and 0.54 (95% CI, 0.46-0.64) for 400-mg twice daily celecoxib compared with placebo. Aspirin use was not independently associated with recurrent adenoma (RR, 0.98, 95% CI, 0.86-1.15). These results did not vary according to UGT1A6 genotype. However, among those with a variant UGT1A6 genotype on aspirin, the RR of adenoma was 1.60 (95% CI, 0.81-3.15) after withdrawal of 200-mg twice daily and 1.98 (95% CI, 1.06-3.70) after withdrawal of 400-mg twice daily celecoxib compared with withdrawal of placebo. In contrast, there was no increased risk associated with discontinuing celecoxib among any other groups. Concurrent use of low-dose aspirin does not influence the efficacy of celecoxib in adenoma prevention. However, discontinuing celecoxib among aspirin-using individuals who initially developed adenoma despite a UGT1A6 variant genotype resulted in rapid reemergence of disease.

The BATTLE to personalize lung cancer prevention through reverse migration

Agents can enter clinical development for cancer prevention either initially or after previous development for a different indication, such as arthritis, with both approaches consuming many years of development before an agent is fully evaluated for cancer prevention. We propose the following, third approach: reverse migration, that is, importing agents, targets, and study designs to personalize interventions and concepts developed in advanced cancer to the setting of cancer prevention. Importing these "ready-made" features from therapy will allow reverse migration to streamline preventive agent development. We recently reported the Biomarker-integrated Approaches of Targeted Therapy for Lung Cancer Elimination (BATTLE) trial of personalized lung cancer therapy and now propose the reverse migration development of personalized lung cancer prevention based on the BATTLE model.

C-reactive protein and risk of colorectal adenoma according to celecoxib treatment

Inflammation, as measured by the circulating inflammatory marker high-sensitivity C-reactive protein (hsCRP), has been associated with cardiovascular disease. However, data about CRP and risk of colorectal cancer have been conflicting. The Adenoma Prevention with Celecoxib (APC) trial showed that the anti-inflammatory drug celecoxib prevents recurrence of colorectal adenoma but increases risk of cardiovascular events. We examined whether serum hsCRP modified these results. We measured hsCRP from serum specimens provided at study entry by patients enrolled in the APC trial. Patients were stratified according to use of low-dose aspirin, randomized to receive 3 years of treatment with placebo, 200-mg-bid celecoxib, or 400-mg-bid celecoxib, and underwent follow-up colonoscopies at years 1 and 3. Among 1,680 patients, the estimated 3-year cumulative incidence of adenoma was 42% for patients with hsCRP <1 mg/L, compared with 43% [relative risk (RR) = 1.02; 95% CI = 0.85-1.22] for hsCRP 1-3 mg/L, and 41% (RR = 1.10; 95% CI = 0.90-1.34) for hsCRP >3 mg/L. The effect of celecoxib on adenoma recurrence did not vary among patients with high (>3 mg/L) compared with low (≤3 mg/L) hsCRP. However, among patients with high hsCRP, the RR of cardiovascular events compared with placebo was 2.27 (95% CI = 0.72-7.14) for those randomized to celecoxib 200-mg-bid and 3.28 (95% CI = 1.09-9.91) for 400-mg-bid. In contrast, among patients with low hsCRP, the corresponding RRs were 0.99 (95% CI = 0.53-1.83) and 1.11 (95% CI = 0.61-2.02). hsCRP may predict risk of celecoxib-associated cardiovascular toxicity but not adenoma recurrence or celecoxib treatment efficacy. Patients with low hsCRP may be a subgroup with a favorable risk-benefit profile for celecoxib chemoprevention.

A strong case for personalized, targeted cancer prevention

The study reported by Lee and colleagues in this issue of the journal (beginning on page 185) incorporated global genetic variation within a new assessment of the outcome of a previously reported phase-III trial of low-dose 13-cis-retinoic acid (13-cRA) for preventing second primary tumors (SPT) or the recurrence of head-and-neck cancer. This analysis identified genotypes of common single-nucleotide polymorphisms (SNP) and cumulative effect and potential gene-gene interactions that were highly associated with increased placebo-arm risk (prognostic) and/or with reduced treatment-arm risk and longer event-free survival (predictive). For example, the wild-type rs3118570 SNP of the retinoid X receptor alpha gene (carried by 71% of the 13-cRA trial population) marked a 3.33-fold increased SPT/recurrence risk in the placebo arm and a 38% reduced risk in the treatment arm. Adding two other informative genotypes strengthened the treatment-arm risk reduction to 76%, although the genotype trio reflected only 13% of the trial population. This report extends the concept of personalized therapy to cancer prevention.

Optical molecular imaging and its emerging role in colorectal cancer

Colorectal cancer remains a major cause of morbidity and mortality in the United States. The advent of molecular therapies targeted against specific, stereotyped cellular mutations that occur in this disease has ushered in new hope for treatment options. However, key questions regarding optimal dosing schedules, dosing duration, and patient selection remain unanswered. In this review, we describe how recent advances in molecular imaging, specifically optical molecular imaging with fluorescent probes, offer potential solutions to these questions. We begin with an overview of optical molecular imaging, including discussions on the various methods of design for fluorescent probes and the clinically relevant imaging systems that have been built to image them. We then focus on the relevance of optical molecular imaging to colorectal cancer. We review the most recent data on how this imaging modality has been applied to the measurement of treatment efficacy for currently available as well as developmental molecularly targeted therapies. We then conclude with a discussion on how this imaging approach has already begun to be translated clinically for human use.

The safety and efficacy of celecoxib in children with familial adenomatous polyposis

OBJECTIVES

Celecoxib is approved as an adjunctive chemopreventive agent in adults with familial adenomatous polyposis (FAP). Its safety and efficacy for colorectal polyps in children is unknown. We evaluated the short-term (3 months) safety and preliminary efficacy of celecoxib in children with FAP.

METHODS

This was a phase I, dose-escalation trial, with three successive cohorts of six children. Children of ages 10-14 years with APC gene mutations and/or adenomas with a family history of FAP were studied at M.D. Anderson Cancer Center and the Cleveland Clinic. Colonoscopy was performed at baseline and month 3. Random assignment was in a 2:1 generic:placebo ratio, escalating from cohort 1 (4 mg/kg/day) to cohort 2 (8 mg/kg/day) to cohort 3 (16 mg/kg/day). Adherence and adverse event (AE) monitoring was conducted at 2-week intervals during drug administration. Safety profile, difference in number, and percent change in colorectal polyps were compared among the four treatments (placebo and the three dose-escalation groups).

RESULTS

Eighteen subjects completed drug dosing and both colonoscopies. Median age was 12.3 years (56% female). No clinically meaningful differences in AEs were seen between placebo subjects and subjects at any of the three celecoxib doses. Median polyp count at baseline was 31. There was a 39.1% increase in the number of polyps in placebo subjects at month 3, whereas in the highest dose celecoxib group, 16 mg/kg/day, a 44.2% reduction was seen (P=0.01).

CONCLUSIONS

Celecoxib at a dose of 16 mg/kg/day, corresponding to the adult dose of 400 mg BID, is safe, well tolerated, and significantly reduced the number of colorectal polyps in children with FAP.

Unprecedented opportunities and promise for cancer prevention research

Cancer prevention encompasses a wide range of highly developed science and clinical impact. Enunciating these two aspects in the same breath highlights the crucial link between them. The breadth and excitement of current opportunities in the science of cancer prevention have never been greater. Major avenues of such research include the extent and effect of premalignancy, the molecular underpinnings of carcinogenesis and related prevention targets, in vitro model systems of the progression of normal human epithelial cells to tumorigenesis, molecular risk stratification and pharmacogenomic approaches, and many more. We describe the clinical impacts of cancer prevention (with examples in the areas of molecular targeting, vaccines, epidemiology, and behavioral science) and the stage-setting science that facilitated them. In addition, discussed are new prevention opportunities such as interactions between stromal and microenvironmental factors, the control of premalignant stem cell phenotypes through epigenetic reprogramming, and neoplastic cells and various stress responses including those involving telomere biology. The promise of this science, particularly integrative, interdisciplinary research, is to hasten the ability of clinical prevention to reduce the burden of cancer.

Cyclooxygenase-2 and cancer treatment: understanding the risk should be worth the reward

Targeting the prostaglandin (PG) pathway is potentially a critical intervention for the prevention and treatment of cancer. Central to PG biosynthesis are two isoforms of cyclooxygenase (COX 1 and 2), which produce prostaglandin H(2) (PGH(2)) from plasma membrane stores of fatty acids. COX-1 is constitutively expressed, whereas COX-2 is an inducible isoform upregulated in many cancers. Differences between COX-1 and COX-2 catalytic sites enabled development of selective inhibitors. Downstream of the COX enzymes, prostaglandin E(2) synthase converts available PGH(2) to prostaglandin E(2) (PGE(2)), which can stimulate cancer progression. Significant research efforts are helping identify more selective targets and fully elucidate the downstream targets of prostaglandin E(2)-mediated oncogenesis. Nonetheless, as a key rate-limiting control point of PG biosynthesis, COX-2 continues to be an important anticancer target. As we embark upon a new era of individualized medicine, a better understanding of the individual risk and/or benefit involved in COX-2 selective targeting is rapidly evolving. This review endeavors to summarize developments in our understanding of COX-2 and its downstream targets as vital areas of anticancer research and to provide the current status of an exciting aspect of molecular medicine.

Current concepts in colorectal cancer prevention

Colorectal cancer chemoprevention, or chemoprophylaxis, is a drug-based approach to prevent colorectal cancer. Preventing colorectal adenomas with currently available agents demonstrates the promise of pharmacologic strategies directed at critical regulatory pathways. However, agent toxicity, lesion breakthrough and competing efficacy from endoscopy procedures challenge population-based implementation. This article reviews the role of colorectal cancer chemoprevention in the context of existing screening and surveillance guidelines and practice. Emphasis is placed on the role of the colorectal adenoma as a cancer precursor and its surrogacy in assessing individual risk and for evaluating chemoprevention efficacy. We discuss the importance of risk stratification for identifying subjects at moderate-to-high risk for colorectal cancer who are most likely to benefit from chemoprevention at an acceptable level of risk.

Cancer prevention: from 1727 to milestones of the past 100 years

The rich, multidisciplinary history of cancer prevention recounted here begins with surgical and workplace recommendations of the 1700s and ends with 2009 results of the enormous (35,535 men) Selenium and Vitamin E [prostate] Cancer Prevention Trial (SELECT). This history comprises a fascinating array of chemopreventive, vaccine, surgical, and behavioral science research, both preclinical and clinical. Preclinical milestones of cancer prevention include the 1913 and 1916 mouse studies by Lathrop and Loeb of cancer development associated with pregnancy or cancer prevention through castration (oophorectomy), preventing chemically induced mouse carcinogenesis as early as 1929, energy restriction studies in the 1940s, the 1950s discoveries and later molecular characterizations of field cancerization and multistep carcinogenesis, and the effects of angiogenesis inhibition in genetically engineered mice reported in 2009. The extraordinary panoply of clinical research includes numerous large and smaller chemoprevention studies of nutritional supplements, other dietary approaches, a Bacillus Calmette-Guérin trial in 1976, molecular-targeted agents, and agents to prevent infection-related cancers such as hepatitis B virus vaccine to prevent liver cancer in 1984. Clinical surgical prevention includes removal of intraepithelial neoplasia detected by screening (including Pap testing developed in 1929 and culposcopy for cervical premalignancy and colonoscopy and polypectomy to prevent colorectal cancer begun in the 1960s) and prophylactic surgeries, such as in Lynch syndrome patients begun in 1977. Behavioral studies include smoking cessation and control beginning in the 1950s, obesity control rooted in studies of 1841, and genetic-counseling and cancer-survivorship studies. This history of pioneering events may help in better understanding who we are and what we want to achieve as cancer prevention researchers and practitioners.