Aspirin suppresses the mutator phenotype associated with hereditary nonpolyposis colorectal cancer by genetic selection

Development and assessment of immediate-release tablets containing clopidogrel bisulphate & aspirin-strategy for optimizing the combination formulation

The main goal of the study was to improve the compliance and convenience of patients by designing and development of an immediate release (IR) fixed-dose combination (Clopidogrel bisulphate and Aspirin) tablets. The proposed combination product utilizes Clopidogrel to protect the moisture-sensitive aspirin component, enhancing its stability against atmospheric conditions. Response-surface approach (Design Expert vs. 13) was used to generate this IR tablet by calculating the right composition of independent variables such as Microcrystalline cellulose 102, pregelatinized starch and Hydroxypropyl cellulose. 32 factorial design was used to estimate the effects of these independent variables on the responses of dependent variables (disintegration & friability) and constructed a total of nine (9) formulations. Pre and Post formulation, quality control parameters were investigated as per pharmacopeia. A systematic approach was used for the optimization process and a prototype checkpoint batch (CPB) based on the better contrast of independent variables was prepared. In vitro analysis of formulations was carried out to estimate the responses. Friability was found in the range of 0.088-1.076%w/w, except F1 = 1.076 all are within limits (NMT 1.0%). Disintegration time was recorded 7.3 ± 1.20 as lower and 24.5 ± 1.63 min was the highest. The release of drugs from their dosage form was fast and rapid, for clopidogrel after 15min was 70.42-96.82% with SD ± 8.71 and aspirin was 69.88-91.49% in 15 min with SD ± 6.41, all the tablets were released more than 80% in 20 min. The stability outcomes of CPB tablets after 15 days of stress study (60 ± 2°C and 75 ± 5%) indicated good compatibility and stability of APIs with excipients. It was concluded that the direct compression method can be preferred to prepare a combination product with cost-effectiveness. It was also concluded that the proposed methodology could increase Aspirin's stability and allow for an aqueous coating system to finish the product with a film coating. By using Design Expert software, the best composition of the formulation can be selected and optimized in a short period of time with minimum trial and errors. The results also demonstrated that the use of a fixed-dose combination tablet instead of the individual is expected to be more convenient to patients and thus improves patient compliance and decreases the occurrence of adverse effects and side effects.

Chemoprevention in Inherited Colorectal Cancer Syndromes

Cancer prevention in hereditary gastrointestinal predisposition syndromes relies primarily on intensive screening (e.g., colonoscopy) or prophylactic surgery (e.g., colectomy). The use of chemopreventive agents as an adjunct to these measures has long been studied both in the general population and in hereditary cancer patients, in whom the risk of malignancy, and therefore the potential risk reduction, is considerably greater. However, to date only few compounds have been found to be effective, safe, and tolerable for widespread use. Furthermore, many of the studies involving these rare syndromes suffer from small sample sizes, heterogeneous patient cohorts, short follow-up duration, and lack of standardized endpoints, creating challenges to draw generalizable conclusion regarding efficacy. The following review summarizes the current data on various chemopreventive compounds used in Lynch syndrome and familial adenomatous polyposis in addition to several agents that are currently being investigated.

Aspirin and cancer treatment: systematic reviews and meta-analyses of evidence: for and against

Aspirin as a possible treatment of cancer has been of increasing interest for over 50 years, but the balance of the risks and benefits remains a point of contention. We summarise the valid published evidence 'for' and 'against' the use of aspirin as a cancer treatment and we present what we believe are relevant ethical implications. Reasons for aspirin include the benefits of aspirin taken by patients with cancer upon relevant biological cancer mechanisms. These explain the observed reductions in metastatic cancer and vascular complications in cancer patients. Meta-analyses of 118 observational studies of mortality in cancer patients give evidence consistent with reductions of about 20% in mortality associated with aspirin use. Reasons against aspirin use include increased risk of a gastrointestinal bleed though there appears to be no valid evidence that aspirin is responsible for fatal gastrointestinal bleeding. Few trials have been reported and there are inconsistencies in the results. In conclusion, given the relative safety and the favourable effects of aspirin, its use in cancer seems justified, and ethical implications of this imply that cancer patients should be informed of the present evidence and encouraged to raise the topic with their healthcare team.

Aspirin Use and Common Cancer Risk: A Meta-Analysis of Cohort Studies and Randomized Controlled Trials

Background

Whether aspirin use can decrease or increase cancer risk remains controversial. In this study, a meta-analysis of cohort studies and randomized controlled trials (RCTs) were conducted to evaluate the effect of aspirin use on common cancer risk.

Method

Medline and Embase databases were searched to identify relevant studies. Meta-analyses of cohort studies and RCTs were performed to assess the effect of aspirin use on the risk of colorectal, gastric, breast, prostate and lung cancer. Cochran Q test and the I square metric were calculated to detect potential heterogeneity among studies. Subgroup meta-analyses according to exposure categories (frequency and duration) and timing of aspirin use (whether aspirin was used before and after cancer diagnosis) were also performed. A dose-response analysis was carried out to evaluate and quantify the association between aspirin dose and cancer risk.

Results

A total of 88 cohort studies and seven RCTs were included in the final analysis. Meta-analyses of cohort studies revealed that regular aspirin use reduced the risk of colorectal cancer (CRC) (RR=0.85, 95%CI: 0.78-0.92), gastric cancer (RR=0.67, 95%CI: 0.52-0.87), breast cancer (RR=0.93, 95%CI: 0.87-0.99) and prostate cancer (RR=0.92, 95%CI: 0.86-0.98), but showed no association with lung cancer risk. Additionally, meta-analyses of RCTs showed that aspirin use had a protective effect on CRC risk (OR=0.74, 95%CI: 0.56-0.97). When combining evidence from meta-analyses of cohorts and RCTs, consistent evidence was found for the protective effect of aspirin use on CRC risk. Subgroup analysis showed that high frequency aspirin use was associated with increased lung cancer risk (RR=1.05, 95%CI: 1.01-1.09). Dose-response analysis revealed that high-dose aspirin use may increase prostate cancer risk.

Conclusions

This study provides evidence for low-dose aspirin use for the prevention of CRC, but not other common cancers. High frequency or high dose use of aspirin should be prescribed with caution because of their associations with increased lung and prostate cancer risk, respectively. Further studies are warranted to validate these findings and to find the minimum effective dose required for cancer prevention.

Aspirin and Statin Use and the Risk of Gallbladder Cancer

Simple Summary

The effects of aspirin on various gastrointestinal cancers have been extensively studied, but the potential protective effect of aspirin and statins on the prevention of gallbladder cancer (GBC) has not been adequately evaluated. The anticancer effect of aspirin has been attributed to direct inhibition of cyclooxygenase (COX)-2. Interestingly, increased expression of COX-2 has been documented in GBC. Hence, we hypothesized that aspirin could potentially have a preventive role in decreasing the risk of GBC. In this study, we demonstrated that the use of aspirin either alone or in combination with statins was associated with a strong reduction in risk of GBC.

Abstract

Aspirin and statin drugs have been associated with reduced risk of several gastrointestinal cancers, but their association with gallbladder cancer (GBC) has not been well established. We evaluated the association of aspirin and statins with the risk of GBC. Patients with GBC managed at Mayo Clinic between 2000 and 2019 were matched 1:2 with a general patient pool by age and sex. Univariable and multivariable logistic regression models were used to assess associations between GBC and aspirin or statin use. The analysis included 795 cases and 1590 controls, with a median age of 67 years. Aspirin or statin use alone or in combination was higher in controls (p < 0.001). Univariate analysis showed that the use of aspirin [odds ratio (OR): 0.11; 95%CI: 0.08–0.15] or statins (OR: 0.29; 95%CI: 0.20–0.40) and their combined use (OR: 0.18; 95%CI: 0.13–0.24) was associated with lower risk of GBC. Multivariable analysis revealed that aspirin (OR: 0.12; 95%CI: 0.09–0.16) and combined statins and aspirin (OR: 0.46; 95%CI: 0.31–0.67) were associated with lower risk of GBC. Aspirin alone or in combination with statins is associated with a strongly reduced risk of GBC. Further prospective studies are needed to confirm these results and to elucidate their mechanisms.

Aspirin in the Prevention of Colorectal Neoplasia

High-quality evidence indicates that regular use of aspirin is effective in reducing the risk for precancerous colorectal neoplasia and colorectal cancer (CRC). This has led to US and international guidelines recommending aspirin for the primary prevention of CRC in specific populations. In this review, we summarize key questions that require addressing prior to broader adoption of aspirin-based chemoprevention, review recent evidence related to the benefits and harms of aspirin use among specific populations, and offer a rationale for precision prevention approaches. We specifically consider the mechanistic implications of evidence showing differences in aspirin's effects according to age, the potential role of modifiable mechanistic biomarkers for personalizing prevention, and emerging evidence that the gut microbiota may offer novel aspirin-associated preventive targets to reduce high-risk neoplasia.

Repurposing of Drugs-The Ketamine Story

An intranasal formulation of esketamine, the S enantiomer of ketamine, in conjunction with an oral antidepressant, has been approved by the FDA for treating treatment-resistant major depressive disorder (TRD) in 2019, almost 50 years after it was approved as an intravenous anesthetic. In contrast to traditional antidepressants, ketamine shows a rapid (within 2 h) and sustained (∼7 days) antidepressant effect and has significant positive effects on antisuicidal ideation. Ketamine's antidepressant mechanism is predominantly mediated by the N-methyl-d-aspartate receptor (NMDA) receptor, although NMDA-independent mechanisms are not ruled out. At the neurocircuitry level, ketamine affects the brain's reward and mood circuitry located in the corticomesolimbic structures involving the hippocampus, nucleus accumbens, and prefrontal cortex. Repurposing of ketamine for treating TRD provided a new understanding of the pathophysiology of depression, a paradigm shift from monoamine to glutamatergic neurotransmission, thus making it a unique tool to investigate the brain and its complex neurocircuitries.

Effects of aspirin on the gastrointestinal tract: Pros vs. cons

Acetylsalicylic acid, also known as aspirin, is often used in clinical antipyretic, analgesic and antiplatelet therapy. Aspirin can cause numerous side effects in the gastrointestinal (GI) tract, ranging from unpleasant GI symptoms without gastric mucosal lesions to ulcer bleeding and even death. However, recent studies have found that aspirin can significantly prevent GI tumors. Despite impressive advances in cancer research, screening and treatment options, GI tumors remain a leading cause of death worldwide. Prevention is a far better option than treatment for tumors. Therefore, the present review assesses the pros and cons of aspirin on the GI tract and, on this the basis, the appropriate dose of aspirin to protect it.

Cancer prevention with aspirin in hereditary colorectal cancer (Lynch syndrome), 10-year follow-up and registry-based 20-year data in the CAPP2 study: a double-blind, randomised, placebo-controlled trial

BACKGROUND

Lynch syndrome is associated with an increased risk of colorectal cancer and with a broader spectrum of cancers, especially endometrial cancer. In 2011, our group reported long-term cancer outcomes (mean follow-up 55·7 months [SD 31·4]) for participants with Lynch syndrome enrolled into a randomised trial of daily aspirin versus placebo. This report completes the planned 10-year follow-up to allow a longer-term assessment of the effect of taking regular aspirin in this high-risk population.

METHODS

In the double-blind, randomised CAPP2 trial, 861 patients from 43 international centres worldwide (707 [82%] from Europe, 112 [13%] from Australasia, 38 [4%] from Africa, and four [<1%] from The Americas) with Lynch syndrome were randomly assigned to receive 600 mg aspirin daily or placebo. Cancer outcomes were monitored for at least 10 years from recruitment with English, Finnish, and Welsh participants being monitored for up to 20 years. The primary endpoint was development of colorectal cancer. Analysis was by intention to treat and per protocol. The trial is registered with the ISRCTN registry, number ISRCTN59521990.

FINDINGS

Between January, 1999, and March, 2005, 937 eligible patients with Lynch syndrome, mean age 45 years, commenced treatment, of whom 861 agreed to be randomly assigned to the aspirin group or placebo; 427 (50%) participants received aspirin and 434 (50%) placebo. Participants were followed for a mean of 10 years approximating 8500 person-years. 40 (9%) of 427 participants who received aspirin developed colorectal cancer compared with 58 (13%) of 434 who received placebo. Intention-to-treat Cox proportional hazards analysis revealed a significantly reduced hazard ratio (HR) of 0·65 (95% CI 0·43-0·97; p=0·035) for aspirin versus placebo. Negative binomial regression to account for multiple primary events gave an incidence rate ratio of 0·58 (0·39-0·87; p=0·0085). Per-protocol analyses restricted to 509 who achieved 2 years' intervention gave an HR of 0·56 (0·34-0·91; p=0·019) and an incidence rate ratio of 0·50 (0·31-0·82; p=0·0057). Non-colorectal Lynch syndrome cancers were reported in 36 participants who received aspirin and 36 participants who received placebo. Intention-to-treat and per-protocol analyses showed no effect. For all Lynch syndrome cancers combined, the intention-to-treat analysis did not reach significance but per-protocol analysis showed significantly reduced overall risk for the aspirin group (HR=0·63, 0·43-0·92; p=0·018). Adverse events during the intervention phase between aspirin and placebo groups were similar, and no significant difference in compliance between intervention groups was observed for participants with complete intervention phase data; details reported previously.

INTERPRETATION

The case for prevention of colorectal cancer with aspirin in Lynch syndrome is supported by our results.

FUNDING

Cancer Research UK, European Union, MRC, NIHR, Bayer Pharma AG, Barbour Foundation.

Drug repositioning: a brief overview

OBJECTIVES

Drug repositioning, that is, the use of a drug in an indication other than the one for which it was initially marketed, is a growing trend. Its origins lie mainly in the attrition experienced in recent years in the field of new drug discovery.

KEY FINDINGS

Despite some regulatory and economic challenges, drug repositioning offers many advantages, and a number of recent successes have confirmed both its public health benefits and its commercial value. The first examples of successful drug repositioning mainly came about through serendipity like acetylsalicylic acid, thalidomide, sildenafil or dimethylfumarate.

CONCLUSION

The history of great-repositioned drugs has given some solutions to various pathologies. Serendipity is not yet useful to find repositioning drugs. Drug repositioning is of growing interest. Nowadays, a more rational approach to the identification of drug candidates for repositioning is possible, especially using data mining.

Microsatellite instability: a review of what the oncologist should know

The patients with high microsatellite instability (MSI-H)/mismatch repair deficient (dMMR) tumors recently have been reported that can benefit from immunotherapy, and MSI can be used as a genetic instability of a tumor detection index. However, many studies have shown that there are many heterogeneous phenomena in patients with MSI tumors in terms of immunotherapy, prognosis and chemotherapy sensitivity. Here we mainly review the research results of MSI detection methods, the mechanisms of MSI occurrence and its relationship with related tumors, aiming to make a brief analysis of the current research status of MSI and provide comparable reference and guidance value for further research in this field.

Endometrial cancer prevention in high-risk women

Endometrial cancer (EC) is the most common gynaecological malignancy, and its incidence is rising alongside the growing prevalence of obesity. Effective risk-reducing interventions hijacking the key mechanisms driving endometrial carcinogenesis may affect EC diagnoses if aimed at those at greatest risk. An understanding of the key risk factors and their role in tumourigenesis is critical in developing such prevention strategies. In this review, we summarise the major risk factors for EC and the evidence for available risk-reducing interventions in high-risk women. We suggest potential prevention strategies and make a case for the need for risk prediction models that identify specific groups of women at a particularly high risk of EC for whom risk-reducing interventions are likely to have a significant impact.

A novel mechanism for the anticancer activity of aspirin and salicylates

Epidemiological studies indicate that long‑term aspirin usage reduces the incidence of colorectal cancer (CRC) and may protect against other non‑CRC associated adenocarcinomas, including oesophageal cancer. A number of hypotheses have been proposed with respect to the molecular action of aspirin and other non‑steroidal anti‑inflammatory drugs in cancer development. The mechanism by which aspirin exhibits toxicity to CRC has been previously investigated by synthesising novel analogues and derivatives of aspirin in an effort to identify functionally significant moieties. Herein, an early effect of aspirin and aspirin‑like analogues against the SW480 CRC cell line was investigated, with a particular focus on critical molecules in the epidermal growth factor (EGF) pathway. The present authors proposed that aspirin, diaspirin and analogues, and diflunisal (a salicylic acid derivative) may rapidly perturb EGF and EGF receptor (EGFR) internalisation. Upon longer incubations, the diaspirins and thioaspirins may inhibit EGFR phosphorylation at Tyr1045 and Tyr1173. It was additionally demonstrated, using a qualitative approach, that EGF internalisation in the SW480 cell line may be directed to endosomes by fumaryldiaspirin using early endosome antigen 1 as an early endosomal marker and that EGF internalisation may also be perturbed in oesophageal cell lines, suggestive of an effect not only restricted to CRC cells. Taken together and in light of our previous findings that the aspirin‑like analogues can affect cyclin D1 expression and nuclear factor‑κB localisation, it was hypothesized that aspirin and aspirin analogues significantly and swiftly perturb the EGFR axis and that the protective activity of aspirin may in part be explained by perturbed EGFR internalisation and activation. These findings may also have implications in understanding the inhibitory effect of aspirin and salicylates on wound healing, given the critical role of EGF in the response to tissue trauma.

Cancer prevention by aspirin in children with Constitutional Mismatch Repair Deficiency (CMMRD)

Constitutional MisMatch Repair Deficiency (CMMRD) is caused by homozygous or compound heterozygous germline variants in one of the mismatch repair (MMR) genes (MSH2, MSH6, PMS2, MLH1). This syndrome results in early onset colorectal cancer, leukemia and lymphoma, brain tumors and other malignancies. Children with CMMRD are at high risk of developing multiple cancers and cancer surveillance does not guarantee detection of cancer at a curable stage. The development of a preventive treatment strategy would be a major step forward. Long-term daily use of acetylsalicylic acid (ASA) has been shown to reduce cancer risk in individuals with Lynch syndrome (LS). LS is caused by heterozygous germline variants of MSH2, MSH6, PMS2 and MLH1 and characterized by an increased risk of developing colorectal and endometrial cancer at adult age. Here we discuss the potential use of ASA for cancer prevention in patients with CMMRD.

Associations between aspirin use and the risk of cancers: a meta-analysis of observational studies

Background

Epidemiological studies have clarified the potential associations between regular aspirin use and cancers. However, it remains controversial on whether aspirin use decreases the risk of cancers risks. Therefore, we conducted an updated meta-analysis to assess the associations between aspirin use and cancers.

Methods

The PubMed, Embase, and Web of Science databases were systematically searched up to March 2017 to identify relevant studies. Relative risks (RRs) with 95% confidence intervals (CIs) were used to assess the strength of associations.

Results

A total of 218 studies with 309 reports were eligible for this meta-analysis. Aspirin use was associated with a significant decrease in the risk of overall cancer (RR = 0.89, 95% CI: 0.87–0.91), and gastric (RR = 0.75, 95% CI: 0.65–0.86), esophageal (RR = 0.75, 95% CI: 0.62–0.89), colorectal (RR = 0.79, 95% CI: 0.74–0.85), pancreatic (RR = 0.80, 95% CI: 0.68–0.93), ovarian (RR = 0.89, 95% CI: 0.83–0.95), endometrial (RR = 0.92, 95% CI: 0.85–0.99), breast (RR = 0.92, 95% CI: 0.88–0.96), and prostate (RR = 0.94, 95% CI: 0.90–0.99) cancers, as well as small intestine neuroendocrine tumors (RR = 0.17, 95% CI: 0.05–0.58).

Conclusions

These findings suggest that aspirin use is associated with a reduced risk of gastric, esophageal, colorectal, pancreatic, ovarian, endometrial, breast, and prostate cancers, and small intestine neuroendocrine tumors.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4156-5) contains supplementary material, which is available to authorized users.

Microsatellite Instability in Mouse Models of Colorectal Cancer

Microsatellite instability (MSI) is caused by DNA mismatch repair deficiency and is an important prognostic and predictive biomarker in colorectal cancer but relatively few studies have exploited mouse models in the study of its clinical utility. Furthermore, most previous studies have looked at MSI in the small intestine rather than the colon of mismatch repair deficient Msh2-knockout (KO) mice. Here we compared Msh2-KO, p53-KO, and wild type (WT) mice that were treated with the carcinogen azoxymethane (AOM) and the nonsteroidal anti-inflammatory drug sulindac or received no treatment. The induced tumors and normal tissue specimens from the colon were analysed with a panel of five mononucleotide repeat markers. MSI was detected throughout the normal colon in untreated Msh2-KO mice and this involved contraction of the repeat sequences compared to WT. The markers with longer mononucleotide repeats (37-59) were the most sensitive for MSI while the markers with shorter repeats (24) showed only minor change. AOM exposure caused further contraction of the Bat37 and Bat59 repeats in the distal colon of Msh2-KO mice which was reversed by sulindac. Thus AOM-induced carcinogenesis is associated with increased instability of mononucleotide repeats in the colon of Msh2-KO mice but not in WT or p53-KO mice. Chemoprevention of these tumors by sulindac treatment reversed or prevented the increased MSI.

Mutation of TGFβ-RII eliminates NSAID cancer chemoprevention

Non-steroidal anti-inflammatory drugs (NSAIDs) exhibit anti-neoplastic (chemoprevention) activity for sporadic cancers and the hereditary cancer predisposition Lynch syndrome (LS/HNPCC). However, the mechanism of NSAID tumor suppression has remained enigmatic. Defects in the core mismatch repair (MMR) genes MSH2 and MLH1 are the principal drivers of LS/HNPCC. Previous work has demonstrated that the villin-Cre^+/−Msh2^flox/flox (VpC-Msh2) mouse is a reliable model for LS/HNPCC intestinal tumorigenesis, which is significantly suppressed by treatment with the NSAID aspirin (ASA) similar to human chemoprevention. Here we show that including a TGFβ receptor type-II (Tgfβ-RII) mutation in the VpC-Msh2 mouse (villin-Cre^+/−Msh2^flox/floxTgfβ−RII^flox/flox) completely eliminates NSAID tumor suppression. These results provide strong genetic evidence that TGFβ signaling and/or effectors participate in NSAID-dependent anti-neoplastic processes and provide fresh avenues for understanding NSAID chemoprevention and resistance.

Genetic Testing for Hereditary Nonpolyposis Colorectal Cancer (HNPCC)

Hereditary nonpolyposis colorectal cancer (HNPCC), also called Lynch syndrome, is an autosomal dominant cancer syndrome that confers an elevated risk of early-onset colorectal cancer (CRC) and increased lifetime risk for other cancers of the endometrium, stomach, small intestine, hepatobiliary system, kidney, ureter, and ovary. Lynch syndrome accounts for up to 3% of all CRC, making it the most common hereditary colorectal cancer syndrome. Germline mutations in methyl-directed mismatch repair (MMR) genes give rise to microsatellite instability (MSI) in tumor DNA. Lynch syndrome is most frequently caused by pathogrenic variants in the mismatch repair genes MLH1, MSH2, MSH6, and PMS2. Germline mutations in MLH1 and MSH2 account for approximately 90% of detected mutations in families with Lynch syndrome. Pathogenic vatiants in MSH6 have been reported in approximately 7-10% of families with Lynch syndrome. Pathogenic variants in PMS2 account for fewer than 5% of mutations in families with Lynch syndrome. This unit presents a comprehensive molecular genetic testing strategy for Lynch syndrome including MSI analysis, next generation sequencing (NGS)-based targeted sequence analysis, PCR-based Sanger sequencing and microarray-based comparative genomic hybridization (array-CGH). © 2017 by John Wiley & Sons, Inc.

The Effect of Combined Aspirin and Clopidogrel Treatment on Cancer Incidence

BACKGROUND

Multiple studies have shown an association between aspirin treatment and a reduction in newly diagnosed cancer. Conversely, there are conflicting clinical and laboratory data on the effect of combined clopidogrel and aspirin therapy on cancer incidence, including analyses suggesting an increased cancer risk. No large-scale cohort study has been performed to address this issue in a heterogeneous real-world scenario. We investigated the effect of clopidogrel and aspirin on cancer incidence compared with aspirin alone and no antiplatelet therapy.

METHODS

A population-based historical cohort study of subjects aged ≥50 years covered by Clalit Health Services, an Israeli health maintenance organization, was performed. Patients treated with the newer antiplatelet drugs, prasugrel or ticagrelor, which, like clopidogrel, inhibit adenosine diphosphate receptors, and those with prior cancer were excluded. Prescription records of antiplatelet medication were retrieved.

RESULTS

The cohort included 183,912 subjects diagnosed with 21,974 cancer cases based upon the International Classification of Diseases, Ninth Revision. Dual aspirin and clopidogrel was prescribed in 9.6%, while 49% received aspirin alone and 41% used neither. Compared with nonusers, there was a lower risk of cancer in subjects exposed to aspirin with (hazard ratio [HR] 0.46; 95% confidence interval [CI], 0.44-0.49) or without clopidogrel (HR 0.54; 95% CI, 0.52-0.56), on long-term follow-up. Combined treatment was associated with a lower cancer risk than the aspirin-only group (HR 0.92; 95% CI, 0.86-0.97).

CONCLUSIONS

Dual clopidogrel and aspirin treatment is safe regarding the cancer risk. This study generates the hypothesis that clopidogrel may reduce cancer incidence.

Aspirin in pancreatic cancer: chemopreventive effects and therapeutic potentials

Pancreatic cancer is one of the most aggressive malignancies with dismal prognosis. Recently, aspirin has been found to be an effective chemopreventive agent for many solid tumors. However, the function of aspirin use in pancreatic cancer largely remains unknown. We herein argued that aspirin could also lower the risk of pancreatic cancer. Importantly, aspirin assumes pleiotropic effects by targeting multiple molecules. It could further target the unique tumor biology of pancreatic cancer and modify the cancer microenvironment, thus showing remarkable therapeutic potentials. Besides, aspirin could reverse the chemoradiation resistance by repressing tumor repopulation and exert synergistic potentials with metformin on pancreatic cancer chemoprevention. Moreover, aspirin secondarily benefits pancreatic cancer patients through modestly reducing cancer pain and the risk of venous thromboembolism. Furthermore, new aspirin derivatives and delivery systems might help to improve risk-to-benefit ratio. In brief, aspirin is a promising chemopreventive agent and exerts significant therapeutic potentials in pancreatic cancer.

Celecoxib for the Prevention of Colorectal Adenomas: Results of a Suspended Randomized Controlled Trial

BACKGROUND

Cyclooxygenase (COX)-2 inhibitors such as celecoxib were designed to preserve anti-inflammatory activity without inhibiting COX-1. Downregulation of COX-2 inhibits colorectal carcinogenesis.

METHODS

The Selenium and Celecoxib Trial was a randomized, placebo-controlled trial of once-daily selenium 200 µg and celecoxib 400 mg, alone or together, for colorectal adenoma prevention. Men and women between age 40 and 80 years were eligible following colonoscopic removal of adenomas. The primary outcome was development of new adenomas. Celecoxib was suspended early because of cardiovascular toxicity in other trials. Accrual to selenium or placebo continued. Before suspension, 824 participants were randomly assigned to celecoxib or placebo, of whom 712 (86.4%) were available for analysis. All statistical tests were two-sided.

RESULTS

In the placebo and celecoxib arms of 356 participants each, adenoma detection was 47.5% and 49.7% (relative risk [RR] = 1.04, 95% confidence interval [CI] = 0.90 to 1.21, P = .58), respectively, after median periods of 13.6 and 14.2 months on intervention. Among participants colonoscoped within 12 months of discontinuing intervention (n = 244), overall adenoma recurrence (RR = 0.69, 95% CI = 0.48 to 0.98, P = .04) and recurrence with advanced adenomas (RR = 0.23, 95% CI = 0.07 to 0.80, P = .02) were reduced with celecoxib. Reduction of adenoma recurrence was greatest in participants with previous advanced adenomas. Celecoxib increased risk of hypertension in participants with pre-existing cardiovascular risk factors compared with placebo (hazard ratio = 2.19, 95% CI = 1.07 to 4.50, P = .03).

CONCLUSIONS

Limited-duration celecoxib prevents adenoma recurrence in patients with prior high-risk adenomas, in whom strategies to minimize cardiovascular toxicity might be feasible.

Manipulation of DNA Repair Proficiency in Mouse Models of Colorectal Cancer

Technical and biological innovations have enabled the development of more sophisticated and focused murine models that increasingly recapitulate the complex pathologies of human diseases, in particular cancer. Mouse models provide excellent in vivo systems for deciphering the intricacies of cancer biology within the context of precise experimental settings. They present biologically relevant, adaptable platforms that are amenable to continual improvement and refinement. We discuss how recent advances in our understanding of tumorigenesis and the underlying deficiencies of DNA repair mechanisms that drive it have been informed by using genetically engineered mice to create defined, well-characterized models of human colorectal cancer. In particular, we focus on how mechanisms of DNA repair can be manipulated precisely to create in vivo models whereby the underlying processes of tumorigenesis are accelerated or attenuated, dependent on the composite alleles carried by the mouse model. Such models have evolved to the stage where they now reflect the initiation and progression of sporadic cancers. The review is focused on mouse models of colorectal cancer and how insights from these models have been instrumental in shaping our understanding of the processes and potential therapies for this disease.

Analgesic use and the risk of primary adult brain tumor

Glioma and meningioma are uncommon tumors of the brain with few known risk factors. Regular use of aspirin has been linked to a lower risk of gastrointestinal and other cancers, though evidence for an association with brain tumors is mixed. We examined the association of aspirin and other analgesics with the risk of glioma and meningioma in a large US case-control study. Cases were persons recently diagnosed with glioma or meningioma and treated at medical centers in the southeastern US. Controls were persons sampled from the same communities as the cases combined with friends and other associates of the cases. Information on past use of analgesics (aspirin, other anti-inflammatory agents, and acetaminophen) was collected in structured interviews. Logistic regression was used to estimate odds ratios (ORs) and 95 % confidence intervals (CIs) for analgesic use adjusted for potential confounders. All associations were considered according to indication for use. A total of 1123 glioma cases, 310 meningioma cases and 1296 controls were included in the analysis. For indications other than headache, glioma cases were less likely than controls to report regular use of aspirin (OR 0.69; CI 0.56, 0.87), in a dose-dependent manner (P trend < 0.001). No significant associations were observed with other analgesics for glioma, or any class of pain reliever for meningioma. Results suggest that regular aspirin use may reduce incidence of glioma.

Hereditary cancer syndromes as model systems for chemopreventive agent development

Research in chemoprevention has undergone a shift in emphasis for pragmatic reasons from large, phase III randomized studies to earlier phase studies focused on safety, mechanisms, and utilization of surrogate endpoints such as biomarkers instead of cancer incidence. This transition permits trials to be conducted in smaller populations and at substantially reduced costs while still yielding valuable information. This article will summarize some of the current chemoprevention challenges and the justification for the use of animal models to facilitate identification and testing of chemopreventive agents as illustrated though four inherited cancer syndromes. Preclinical models of inherited cancer syndromes serve as prototypical systems in which chemopreventive agents can be developed for ultimate application to both the sporadic and inherited cancer settings.

Mouse models of DNA mismatch repair in cancer research

Germline mutations in DNA mismatch repair (MMR) genes are the cause of hereditary non-polyposis colorectal cancer/Lynch syndrome (HNPCC/LS) one of the most common cancer predisposition syndromes, and defects in MMR are also prevalent in sporadic colorectal cancers. In the past, the generation and analysis of mouse lines with knockout mutations in all of the known MMR genes has provided insight into how loss of individual MMR genes affects genome stability and contributes to cancer susceptibility. These studies also revealed essential functions for some of the MMR genes in B cell maturation and fertility. In this review, we will provide a brief overview of the cancer predisposition phenotypes of recently developed mouse models with targeted mutations in MutS and MutL homologs (Msh and Mlh, respectively) and their utility as preclinical models. The focus will be on mouse lines with conditional MMR mutations that have allowed more accurate modeling of human cancer syndromes in mice and that together with new technologies in gene targeting, hold great promise for the analysis of MMR-deficient intestinal tumors and other cancers which will drive the development of preventive and therapeutic treatment strategies.

Mesalazine and thymoquinone attenuate intestinal tumour development in Msh2(loxP/loxP) Villin-Cre mice

OBJECTIVE

Lynch syndrome is caused by germline mutations in DNA mismatch repair genes leading to microsatellite instability (MSI) and colorectal cancer. Mesalazine, commonly used for the treatment of UC, reduces MSI in vitro. Here, we tested natural compounds for such activity and applied mesalazine and thymoquinone in a Msh2(loxP/loxP) Villin-Cre mouse model for Lynch syndrome.

DESIGN

Flow cytometry was used for quantitation of mutation rates at a CA13 microsatellite in human colon cancer (HCT116) cells that had been stably transfected with pIREShyg2-enhanced green fluorescent protein/CA13, a reporter for frameshift mutations. Mice were treated for 43 weeks with mesalazine, thymoquinone or control chow. Intestines were analysed for tumour incidence, tumour multiplicity and size. MSI testing was performed from microdissected normal intestinal or tumour tissue, compared with mouse tails and quantified by the number of mutations per marker (NMPM).

RESULTS

Besides mesalazine, thymoquinone significantly improved replication fidelity at 1.25 and 2.5 µM in HCT116 cells. In Msh2(loxP/loxP) Villin-Cre mice, tumour incidence was reduced by mesalazine from 94% to 69% (p=0.04) and to 56% (p=0.003) by thymoquinone. The mean number of tumours was reduced from 3.1 to 1.4 by mesalazine (p=0.004) and to 1.1 by thymoquinone (p<0.001). Interestingly, MSI was reduced in normal intestinal tissue from 1.5 to 1.2 NMPM (p=0.006) and to 1.1 NMPM (p=0.01) by mesalazine and thymoquinone, respectively. Thymoquinone, but not mesalazine, reduced MSI in tumours.

CONCLUSIONS

Mesalazine and thymoquinone reduce tumour incidence and multiplicity in Msh2(loxP/loxP) Villin-Cre mice by reduction of MSI independent of a functional mismatch repair system. Both substances are candidate compounds for chemoprevention in Lynch syndrome mutation carriers.

Identification of aspirin analogues that repress NF-κB signalling and demonstrate anti-proliferative activity towards colorectal cancer in vitro and in vivo

Substantial evidence indicates that aspirin and related non-steroidal anti-inflammatory drugs (NSAIDs) have potential as chemopreventative/therapeutic agents. However, these agents cannot be universally recommended for prevention purposes due to their potential side-effect profiles. Here, we compared the growth inhibitory and mechanistic activity of aspirin to two novel analogues, diaspirin (DiA) and fumaryl diaspirin (F-DiA). We found that the aspirin analogues inhibited cell proliferation and induced apoptosis of colorectal cancer cells at significantly lower doses than aspirin. Similar to aspirin, we found that an early response to the analogues was a reduction in levels of cyclin D1 and stimulation of the NF-κB pathway. This stimulation was associated with a significant reduction in basal levels of NF-κB transcriptional activity, in keeping with previous data for aspirin. However, in contrast to aspirin, DiA and F-DiA activity was not associated with nucleolar accumulation of RelA. For all assays, F-DiA had a more rapid and significant effect than DiA, identifying this agent as particularly active against colorectal cancer. Using a syngeneic colorectal tumour model in mice, we found that, while both agents significantly inhibited tumour growth in vivo, this effect was particularly pronounced for F-DiA. These data identify two compounds that are active against colorectal cancer in vitro and in vivo. They also identify a potential mechanism of action of these agents and shed light on the chemical structures that may be important for the antitumour effects of aspirin.

A dual-fluorescent reporter facilitates identification of thiol compounds that suppress microsatellite instability induced by oxidative stress

The DNA mismatch-repair (MMR) system corrects replicative errors and minimizes mutations that occur at a high rate in microsatellites. Patients with chronic inflammation or inflammation-associated cancer display microsatellite instability (MSI), indicating a possible MMR inactivation. In fact, H2O2-generated oxidative stress inactivates the MMR function and increases mutation accumulation in a reporter microsatellite. However, it remains unclear whether MSI induced by oxidative stress is preventable because of the lack of a sufficiently sensitive detection assay. Here, we developed and characterized a dual-fluorescent system, utilizing DsRed harboring the (CA)13 microsatellite as a reporter and GFP for normalization, in near-isogenic human colorectal cancer cell lines. Via flow cytometry, this reporter sensitively detected H2O2-generated oxidative microsatellite mutations in a dose-dependent manner. The reporter further revealed that glutathione or N-acetylcysteine was better than aspirin and ascorbic acid for suppressing oxidative microsatellite mutations. These two thiol compounds also partially suppressed oxidative frameshift mutations in the coding microsatellites of the hMSH6 and CHK1 genes based on a fluoresceinated PCR-based assay. MSI suppression by N-acetylcysteine appears to be mediated through reduction of oxidative frameshift mutations in the coding microsatellite of hMSH6 and protection of hMSH6 and other MMR protein levels from being decreased by H2O2. Our findings suggest a linkage between oxidative damage, MMR deficiency, and MSI. The two thiol compounds are potentially valuable for preventing inflammation-associated MSI. The dual-fluorescent reporter with improved features will facilitate identification of additional compounds that modulate MSI, which is relevant to cancer initiation and progression.

Polyamine catabolism in carcinogenesis: potential targets for chemotherapy and chemoprevention

Polyamines, including spermine, spermidine, and the precursor diamine, putrescine, are naturally occurring polycationic alkylamines that are required for eukaryotic cell growth, differentiation, and survival. This absolute requirement for polyamines and the need to maintain intracellular levels within specific ranges require a highly regulated metabolic pathway primed for rapid changes in response to cellular growth signals, environmental changes, and stress. Although the polyamine metabolic pathway is strictly regulated in normal cells, dysregulation of polyamine metabolism is a frequent event in cancer. Recent studies suggest that the polyamine catabolic pathway may be involved in the etiology of some epithelial cancers. The catabolism of spermine to spermidine utilizes either the one-step enzymatic reaction of spermine oxidase (SMO) or the two-step process of spermidine/spermine N (1)-acetyltransferase (SSAT) coupled with the peroxisomal enzyme N (1)-acetylpolyamine oxidase. Both catabolic pathways produce hydrogen peroxide and a reactive aldehyde that are capable of damaging DNA and other critical cellular components. The catabolic pathway also depletes the intracellular concentrations of spermidine and spermine, which are free radical scavengers. Consequently, the polyamine catabolic pathway in general and specifically SMO and SSAT provide exciting new targets for chemoprevention and/or chemotherapy.

Chemoprevention in Lynch syndrome

CAPP1 tested aspirin 600 mg/day and/or resistant starch 30 g/day in 200 adolescent FAP carriers. Aspirin treatment resulted in a non-significant reduction in polyp number and a significant reduction in polyp size among patients treated with aspirin for more than 1 year. CAPP2 RCT used the same interventions in 937 Lynch syndrome patients, the first RCT to have cancer prevention as the primary endpoint. Aspirin did not reduce the risk of colorectal neoplasia in a mean treatment period of 29 months but double blind post intervention follow-up has revealed 48 participants developed 53 CRCs. Per protocol analysis showed 63% fewer colon cancers with aspirin (p = 0.008) apparent from 4 years, with a similar effect on other LS cancers. Resistant starch was not beneficial at long term followup. CAPP3 will involve a double blind dose non-inferiority trial comparing 100, 300 or 600 mg daily in 3,000 gene carriers. We can now recommend aspirin in people at high risk of colorectal cancer.

Colorectal cancer prevention: screening and the role of aspirin

SUMMARY Colon cancer is the third most common cancer worldwide. Sigmoidoscopy and colonoscopy, with the removal of rectal and colon polyps, are proven strategies for the prevention of colon cancer, and testing for fecal occult blood helps to identify subjects suitable for endoscopy. Evidence that low-dose aspirin is associated with a substantial reduction in colon cancer risk and reduces the number and growth of colon polyps is accumulating from randomized trials and observational studies. Advantages and disadvantages of endoscopy and aspirin prophylaxis are discussed extensively in this review. The reduction in cancer incidence by the two approaches together is considerably enhanced as they complement each other. Expenditure could become more cost effective if the two were promoted together.

Mechanisms of action of non-steroidal anti-inflammatory drugs (NSAIDs) and mesalazine in the chemoprevention of colorectal cancer

Colorectal cancer (CRC) is the third most common malignant neoplasm worldwide. Although conclusive evidence is still lacking, epidemiologic studies suggest that long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) has chemopreventive properties against CRC. Similarly, regular consumption of mesalazine, a drug structurally related to NSAIDs, seems to reduce the risk of CRC in patients with ulcerative colitis. These observations are supported by a large body of experimental data showing the ability of such drugs to inhibit multiple pathways that sustain colon carcinogenesis. This review summarizes the current information on the molecular mechanisms by which NSAIDs and mesalazine could interfere with CRC cell growth and survival.

Mechanisms of action of non-steroidal anti-inflammatory drugs (NSAIDs) and mesalazine in the chemoprevention of colorectal cancer

Colorectal cancer (CRC) is the third most common malignant neoplasm worldwide. Although conclusive evidence is still lacking, epidemiologic studies suggest that long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) has chemopreventive properties against CRC. Similarly, regular consumption of mesalazine, a drug structurally related to NSAIDs, seems to reduce the risk of CRC in patients with ulcerative colitis. These observations are supported by a large body of experimental data showing the ability of such drugs to inhibit multiple pathways that sustain colon carcinogenesis. This review summarizes the current information on the molecular mechanisms by which NSAIDs and mesalazine could interfere with CRC cell growth and survival.

Genetics, inheritance and strategies for prevention in populations at high risk of colorectal cancer (CRC)

Hereditary forms of colorectal cancer account for less than 5 % of colorectal cancer but attract disproportionate attention because they offer an opportunity for effective surgical prophylaxis, influence the health of the wider family and give insight into the critical pathways of carcinogenesis. Familial Adenomatous Polyposis (FAP) due to loss of the APC gene and Lynch syndrome or Hereditary Non-Polyposis Colon Cancer (HNPCC) due to breakdown in MisMatch Repair are the principal syndromes of broader interest and both have been the subject of chemoprevention trials. There has been a longstanding interest in non-steroidal anti inflammatories in FAP where trials have shown regression of polyps with the "pro drug"sulindac and the selective COX2 inhibitors though impact on long-term cancer risk is not confirmed. The CAPP1 trial focused on two interventions in a factorial design, aspirin and resistant starch or fermentable fibre. Resistant starch is not absorbed in the small intestine and undergoes colonic fermentation to short-chain fatty acids including butyrate which have anti-cancer effects. Polyposis registry clinicians across Europe recruited adolescents with FAP to receive aspirin (600 mg as 2 tablets/d) and/or 30 g as 2 sachets/d in a 1:1 blend of potato starch and high amylose maize starch [Hylon VII]) with placebo control for at least a year or until surgery before age 21. Fifty-nine percent (133/227) of recruits had a baseline and at least one other endoscopy. After a median of 17 months , the primary endpoint of a risk of an increased polyp number in the rectum and sigmoid colon was not significantly reduced in either treatment group with relative risks of 0.77 (aspirin; 95 % CI, 0.54-1.10;) and 1.05 (RS; 95 % CI, 0.73-1.49. The diameter of the largest polyp detected tended to be smaller in the aspirin arm. The planned subgroup analyses of patients who elected to continue on study for more than one year found a significant reduction in the size of the largest polyp in the aspirin versus non-aspirin group (p = 0.02), Mean crypt length decreased significantly over time on study in the two combined RS groups, compared with the two combined non-RS groups (p < 0.0001 for interaction), in a model of the interaction between intervention and time. In CAPP2, 1009 Lynch syndrome gene carriers were recruited from 43 international centres. 937 commenced intervention: 600 mg enteric coated aspirin and/or 30grams of the resistant starch Novelose in a 2 by 2 factorial placebo controlled design. After a mean of 29 months, intervention, there was no evidence that either agent influenced development of colonic neoplasia. However, the design included double blind follow-up for at least 10 years. After a mean of 55.7 months, and despite regular colonoscopy and polyp removal, 48 recruits developed CRC. Of these, 18 received aspirin and 30 received AP; the HR for CRC for aspirin was 0.63 (CI 0.35-1.13, p = 0.12). Five of the 48 people who developed CRC each had two primary colon cancers. Poisson regression analysis to allow for multiple primary events indicated a protective effect: IRR 0.56 (CI 0.32-0.99, p = 0.05). For those who took aspirin (or AP) for a minimum of 2 years (per protocol) the HR was 0.41 (CI 0.19-0.86 p = 0.02) and the IRR, 0.37 (CI 0.18-0.78 p = 0.008). Combined analysis of all LS cancers including CRC revealed a similar effect. On intention to treat analysis, the HR was 0.65 (CI 0.42-1.00, p = 0.05 and IRR was 0.59 (CI 0.39-0.90 p = 0.01), while the Per Protocol analysis HR was 0.45 (CI 0.26-0.79 p = 0.005,) and IRR was 0.42 (CI 0.25-0.72, p = 0.001). Adverse events in the aspirin and placebo groups were similar with 11 significant gastrointestinal bleeds or ulcers in the aspirin group and 9 in the placebo group. The evidence is now sufficient to recommend aspirin to all Lynch syndrome gene carriers. CAPP3 will recruit 3000 gene carriers into a dose inferiority study to test the relative benefits of 100mg, 300 or 600mg daily doses.

Strategies of targeting oral drug delivery systems to the colon and their potential use for the treatment of colorectal cancer

Colorectal cancer (CRC) is the third most common cause of cancer-related death in both men and women. Often, surgical intervention remains the choice in treating CRC. Traditional dosage forms used for treating CRC deliver drug to wanted as well as unwanted sites of drug action resulting in several adverse side effects. Targeted oral drug delivery systems are being investigated to target and deliver chemotherapeutic and chemopreventive agents directly to colon and rectum. Site-specific delivery of a drug to colon increases its concentration at the target site, and thus requires a lower dose with reduced incidence of side effects. The major obstacle to be overcome for successful targeting of drug to colon through oral route is that drug absorption/degradation must be avoided in stomach and small intestine before the dosage form reaches colon. The review includes discussion of physiological factors that must be considered when targeting drugs directly to colorectal region, an outline on drugs used for treatment and prevention of CRC, and a brief description of various types of colon-targeted oral drug delivery systems. The focus is on the assessment of various formulation approaches being investigated for oral colon-specific delivery of drugs used in the treatment and prevention of CRC.

Low-dose aspirin and cancer mortality: a meta-analysis of randomized trials

OBJECTIVE

Low-dose aspirin is a common strategy for preventing cardiovascular disease and associated mortality. A recent individual patient data meta-analysis of 8 trials of low- and high-dose aspirin, with long-term follow-up, found important reductions in cancer mortality. We aimed to determine whether cancer mortality also is reduced by low-dose aspirin in the shorter term.

METHODS

We conducted a comprehensive search of 10 electronic databases up to December 2011. We conducted a meta-analysis using data from all randomized clinical trials evaluating low-dose (75-325 mg) daily aspirin. We extracted data on non-cardiovascular disease mortality and cancer mortality. We pooled studies using a random-effects model and conducted a meta-regression. We supplemented this with a cumulative meta-analysis and trial sequential monitoring analysis.

RESULTS

Twenty-three randomized studies reported on nonvascular death. There were 944 nonvascular deaths of 41,398 (2.28%) patients receiving low-dose aspirin and 1074 nonvascular deaths of 41,470 (2.58%) patients not receiving aspirin therapy. The relative risk of nonvascular death was 0.88 (95% confidence interval [CI], 0.81-0.96, I(2) = 0%). Eleven trials included data evaluating cancer mortality involving 16,066 patients. There were 162 of 7998 (2.02%) and 210 of 8068 (2.60%) cancer deaths among low-dose aspirin users versus non-aspirin users, respectively, reported over an average follow-up of 2.8 years. The relative risk of cancer mortality was 0.77 (95% CI, 0.63-0.95, I(2) = 0%). Studies demonstrated a significant treatment effect after approximately 4 years of follow-up. The optimal information size analysis showed that a sufficient number of patients had been randomized to provide convincing evidence of a preventive role of low-dose aspirin in nonvascular deaths.

CONCLUSION

Nonvascular deaths, including cancer deaths, are reduced with low-dose aspirin.

Colorectal cancer chemoprevention: is this the future of colorectal cancer prevention?

Colorectal cancer (CRC) is presently one of the most common causes of cancer-related death in our setting and affects a great number of people each year. Screening strategies are commonly used but they do not seem enough to avoid CRC development or prevent completely its mortality. Because of this fact other prevention strategies have gained interest in recent years. Chemoprevention seems to be an attractive option in this setting and several drugs have been studied in this field. This review is focused on salicylates, nonsteroidal anti-inflammatory drugs (NSAIDs) and cycloxygenase-2 inhibitors (COXIBs), whose mechanism of action could be directly related to colon cancer chemoprevention.

Effects of aspirin on colorectal cancer related to lynch syndrome

This article is a review of "Long-term effects of aspirin on cancer risk in carriers of hereditary colorectal cancer: An analysis from the CAPP2 randomised controlled trial" by Burn et al. (2011), Lancet, 378, 2081-2087. For another perspective on the Burn et al. article as well as a discussion of challenges faced when interpreting a large prospective trial, please see the related article by Rita Wickham.

Long-term effect of aspirin on cancer risk in carriers of hereditary colorectal cancer: an analysis from the CAPP2 randomised controlled trial

BACKGROUND

Observational studies report reduced colorectal cancer in regular aspirin consumers. Randomised controlled trials have shown reduced risk of adenomas but none have employed prevention of colorectal cancer as a primary endpoint. The CAPP2 trial aimed to investigate the antineoplastic effects of aspirin and a resistant starch in carriers of Lynch syndrome, the major form of hereditary colorectal cancer; we now report long-term follow-up of participants randomly assigned to aspirin or placebo.

METHODS

In the CAPP2 randomised trial, carriers of Lynch syndrome were randomly assigned in a two-by-two factorial design to 600 mg aspirin or aspirin placebo or 30 g resistant starch or starch placebo, for up to 4 years. Randomisation was in blocks of 16 with provision for optional single-agent randomisation and extended postintervention double-blind follow-up; participants and investigators were masked to treatment allocation. The primary endpoint was development of colorectal cancer. Analysis was by intention to treat and per protocol. This trial is registered, ISRCTN59521990.

RESULTS

861 participants were randomly assigned to aspirin or aspirin placebo. At a mean follow-up of 55·7 months, 48 participants had developed 53 primary colorectal cancers (18 of 427 randomly assigned to aspirin, 30 of 434 to aspirin placebo). Intention-to-treat analysis of time to first colorectal cancer showed a hazard ratio (HR) of 0·63 (95% CI 0·35-1·13, p=0·12). Poisson regression taking account of multiple primary events gave an incidence rate ratio (IRR) of 0·56 (95% CI 0·32-0·99, p=0·05). For participants completing 2 years of intervention (258 aspirin, 250 aspirin placebo), per-protocol analysis yielded an HR of 0·41 (0·19-0·86, p=0·02) and an IRR of 0·37 (0·18-0·78, p=0·008). No data for adverse events were available postintervention; during the intervention, adverse events did not differ between aspirin and placebo groups.

INTERPRETATION

600 mg aspirin per day for a mean of 25 months substantially reduced cancer incidence after 55·7 months in carriers of hereditary colorectal cancer. Further studies are needed to establish the optimum dose and duration of aspirin treatment.

FUNDING

European Union; Cancer Research UK; Bayer Corporation; National Starch and Chemical Co; UK Medical Research Council; Newcastle Hospitals trustees; Cancer Council of Victoria Australia; THRIPP South Africa; The Finnish Cancer Foundation; SIAK Switzerland; Bayer Pharma.

Pharmacology and cellular/molecular mechanisms of action of aspirin and non-aspirin NSAIDs in colorectal cancer

Colorectal cancer (CRC) and colorectal adenomas have in common a dysfunctional adenomatous polyposis coli suppressor gene (APC). This allows for activation of the oncogenic Wnt/β-catenin pathway, resulting in cytosolic accumulation of β-catenin, its translocation to the nucleus and action as a cofactor for stimulation of gene transcription. Pharmacological approaches of CRC-chemoprevention are focused to prevention of this β-catenin-mediated oncogenic signalling. Among upregulated genes in tumour tissue is COX-2 which synthesises large amounts of PGE(2). PGE(2) inhibits apoptosis, acts proinflammatory and immunosuppressive and stimulates tumour angiogenesis and proliferation. In addition, COX-2 causes oxidation (activation) of cocarcinogens. Aspirin and non-aspirin NSAIDs inhibit COX-2, subsequent PGE(2) formation and action by transcriptional and non-transcriptional mechanisms. These also include inhibition of generation of sphingosine-1-phosphate, an amplifier of these reactions and stimulation of NSAID-induced gene (NAG-1) which acts as an inhibitor. Aspirin additionally acetylates COX-2, resulting in generation of 'aspirin-triggered' lipoxins (ATL), a new class of anti-inflammatory/antitumour compounds. COX-1 inhibition might also contribute to antitumour effects of aspirin, for example at low-dose aspirin. Experimental evidence suggests additional COX independent actions of aspirin and non-aspirin NSAIDs on oncogenic signalling. This includes modifications of transcription factors (NFκB), induction of apoptosis and DNA stabilization. In comparison to non-aspirin NSAIDs (sulindac, indomethacin) and coxibs (celecoxib), aspirin has the advantage of concomitant antiplatelet effects while NSAIDs rather have a thrombogenic potential. Though these actions of aspirin have to be balanced against an increased bleeding tendency, aspirin is currently the most attractive candidate for clinical CRC chemoprevention. Open questions, such as dose, (minimum) duration of treatment and the individual risk/benefit ratio are subjects of prospective randomized trials which are underway.

Salicylic acid beyond defence: its role in plant growth and development

In recent years salicylic acid (SA) has been the focus of intensive research due to its function as an endogenous signal mediating local and systemic plant defence responses against pathogens. It has also been found that SA plays a role during the plant response to abiotic stresses such as drought, chilling, heavy metal toxicity, heat, and osmotic stress. In this sense, SA appears to be, just like in mammals, an 'effective therapeutic agent' for plants. Besides this function during biotic and abiotic stress, SA plays a crucial role in the regulation of physiological and biochemical processes during the entire lifespan of the plant. The discovery of its targets and the understanding of its molecular modes of action in physiological processes could help in the dissection of the complex SA signalling network, confirming its important role in both plant health and disease. Here, the evidence that supports the role of SA during plant growth and development is reviewed by comparing experiments performed by exogenous application of SA with analysis of genotypes affected by SA levels and/or perception.

Aspirin and low-dose nitric oxide-donating aspirin increase life span in a Lynch syndrome mouse model

Nonsteroidal anti-inflammatory drugs (NSAID) appear to be effective cancer chemopreventives. Previous cellular studies showed that aspirin (acetylsalicylic acid: ASA) and nitric oxide-donating ASA (NO-ASA) suppressed microsatellite instability (MSI) in mismatch repair (MMR)-deficient cells linked to the common cancer predisposition syndrome hereditary nonpolyposis colorectal cancer or Lynch syndrome (LS/HNPCC), at doses 300- to 3,000-fold less than ASA. Using a mouse model that develops MMR-deficient intestinal tumors that appear pathologically identical to LS/HNPCC, we show that ASA (400 mg/kg) and low-dose NO-ASA (72 mg/kg) increased life span by 18% to 21%. We also note a trend where ASA treatment resulted in intestinal tumors with reduced high MSI (H-MSI) and increased low MSI (L-MSI) as defined by the Bethesda Criteria. Low-dose NO-ASA had a minimal effect on MSI status. In contrast to previous studies, high-dose NO-ASA (720/1,500 mg/kg) treatments increased tumor burden, decreased life span, and exacerbated MSI uniquely in the LS/HNPCC mouse model. These results suggest that MMR-deficient tissues/mice may be specifically sensitive to intrinsic pharmacokinetic features of this drug. It is likely that long-term treatment with ASA may represent a chemopreventive option for LS/HNPCC patients. Moreover, as low-dose NO-ASA shows equivalent life span increase at 10-fold lower doses than ASA, it may have the potential to significantly reduce the gastropathy associated with long-term ASA treatment.