Increased toxicity and lack of efficacy of Rofecoxib in combination with chemotherapy for treatment of metastatic colorectal cancer: A phase II study

LTβR-RelB signaling in intestinal epithelial cells protects from chemotherapy-induced mucosal damage

The intricate immune mechanisms governing mucosal healing following intestinal damage induced by cytotoxic drugs remain poorly understood. The goal of this study was to investigate the role of lymphotoxin beta receptor (LTβR) signaling in chemotherapy-induced intestinal damage. LTβR deficient mice exhibited heightened body weight loss, exacerbated intestinal pathology, increased proinflammatory cytokine expression, reduced IL-22 expression, and proliferation of intestinal epithelial cells following methotrexate (MTX) treatment. Furthermore, LTβR-/-IL-22-/- mice succumbed to MTX treatment, suggesting that LTβR- and IL-22- dependent pathways jointly promote mucosal repair. Although both LTβR ligands LIGHT and LTβ were upregulated in the intestine early after MTX treatment, LIGHT-/- mice, but not LTβ-/- mice, displayed exacerbated disease. Further, we revealed the critical role of T cells in mucosal repair as T cell-deficient mice failed to upregulate intestinal LIGHT expression and exhibited increased body weight loss and intestinal pathology. Analysis of mice with conditional inactivation of LTβR revealed that LTβR signaling in intestinal epithelial cells, but not in Lgr5+ intestinal stem cells, macrophages or dendritic cells was critical for mucosal repair. Furthermore, inactivation of the non-canonical NF-kB pathway member RelB in intestinal epithelial cells promoted MTX-induced disease. Based on these results, we propose a model wherein LIGHT produced by T cells activates LTβR-RelB signaling in intestinal epithelial cells to facilitate mucosal repair following chemotherapy treatment.

NSAIDs and Cancer Resolution: New Paradigms beyond Cyclooxygenase

Acute inflammation or resolved inflammation is an adaptive host defense mechanism and is self-limiting, which returns the body to a state of homeostasis. However, unresolved, uncontrolled, or chronic inflammation may lead to various maladies, including cancer. Important evidence that links inflammation and cancer is that nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin, reduce the risk and mortality from many cancers. The fact that NSAIDs inhibit the eicosanoid pathway prompted mechanistic drug developmental work focusing on cyclooxygenase (COX) and its products. The increased prostaglandin E2 levels and the overexpression of COX-2 in the colon and many other cancers provided the rationale for clinical trials with COX-2 inhibitors for cancer prevention or treatment. However, NSAIDs do not require the presence of COX-2 to prevent cancer. In this review, we highlight the effects of NSAIDs and selective COX-2 inhibitors (COXIBs) on targets beyond COX-2 that have shown to be important against many cancers. Finally, we hone in on specialized pro-resolving mediators (SPMs) that are biosynthesized locally and, in a time, -dependent manner to promote the resolution of inflammation and subsequent tissue healing. Different classes of SPMs are reviewed, highlighting aspirin's potential in triggering the production of these resolution-promoting mediators (resolvins, lipoxins, protectins, and maresins), which show promise in inhibiting cancer growth and metastasis.

Understanding chemotherapy-induced intestinal mucositis and strategies to improve gut resilience

Intestinal mucositis remains one of the most debilitating side effects related to chemotherapy. The onset and persistence of mucositis is an intricate physiological process involving cross-communication between the specific chemotherapeutic drug, the immune system, and gut microbes that results in a loss of mucosal integrity leading to gut-barrier dysfunction. Intestinal mucositis has a severe impact on a patient's quality of life and negatively influences the outcome of treatment. Most importantly, intestinal mucositis is a major contributor to the decreased survival rates and early onset of death associated with certain chemotherapy treatments. Understanding the pathophysiology and symptomology of intestinal mucositis is important in reducing the negative consequences of this condition. Prophylaxis, early diagnosis, and proper symptom management are essential to improved survival outcomes in patients with cancer. This review focuses on the pathobiology of intestinal mucositis that accompanies chemotherapy treatments. In addition, we will discuss the therapeutic potential of select strategies that have shown promise in mitigating chemotherapies' off-target effects without hampering their anticancer efficacy.NEW & NOTEWORTHY Intestinal mucositis, or damage to the intestinal mucosa, is a common side effect of chemotherapy. In this review, we describe the pathobiology of intestinal mucositis that is associated with chemotherapy treatments. In addition, we discuss the efficacy of several potential therapeutic strategies that have shown some potential in alleviating chemotherapies' off-target effects.

Cellular signaling pathways implicated in metastasis of colorectal cancer and the associated targeted agents

Colorectal cancer (CRC) is the third leading cancer worldwide and CRC-related death is mainly attributed to metastasis. Many cellular signaling pathways have been demonstrated to be aberrant in colorectal tumors, and some of them lead to the acquisition of malignant phenotypes. Therefore, the evaluation of signaling pathways implicated in CRC metastasis is urgent for further understanding of CRC progression and pharmacotherapy. This review focuses on several novel cellular signaling pathways associated with CRC metastasis, including Wnt/β-catenin, p53, COX, TGF-β/Smad, NF-κB, Notch, VEGF and JAKs/STAT3 signaling pathways. Targeted agents developed based on these pathways are also briefly discussed.

Potency of non-steroidal anti-inflammatory drugs in chemotherapy

Cancer cell resistance, particularly multidrug resistance (MDR), is the leading cause of chemotherapy failure. A number of mechanisms involved in the development of MDR have been described, including the overexpression of ATP-dependent membrane-bound transport proteins. The enhanced expression of these proteins, referred to as ATP-binding cassette (ABC) transporters, results in an increased cellular efflux of the cytotoxic drug, thereby reducing its intracellular concentration to an ineffective level. Non-steroidal anti-inflammatory drugs (NSAIDs) are the most frequently consumed drugs worldwide. NSAIDs are mainly used to treat pain, fever and inflammation. Numerous studies suggest that NSAIDs also show promise as anticancer drugs. NSAIDs have been shown to reduce cancer cell proliferation, motility, angiogenesis and invasiveness. In addition to these effects, NSAIDs have been shown to induce apoptosis in a wide variety of cancer types. Moreover, several studies have indicated that NSAIDs may sensitise cancer cells to the antiproliferative effects of cytotoxic drugs by modulating ABC transporter activity. Therefore, combining specific NSAIDs with chemotherapeutic drugs may have clinical applications. Such treatments may allow for the use of a lower dose of cytotoxic drugs and may also enhance the effectiveness of therapy. The objective of this review was to discuss the possible role of NSAIDs in the modulation of antitumour drug cytotoxicity. We particularly emphasised on the use of COX-2 inhibitors in combination with chemotherapy and the molecular and cellular mechanisms underlying the alterations in outcome that occur in response to this combination therapy.

Inhibition of COX-2 in colon cancer modulates tumor growth and MDR-1 expression to enhance tumor regression in therapy-refractory cancers in vivo

Higher cyclooxygenase 2 (COX-2) expression is often observed in aggressive colorectal cancers (CRCs). Here, we attempt to examine the association between COX-2 expression in therapy-refractory CRC, how it affects chemosensitivity, and whether, in primary tumors, it is predictive of clinical outcomes. Our results revealed higher COX-2 expression in chemoresistant CRC cells and tumor xenografts. In vitro, the combination of either aspirin or celecoxib with 5-fluorouracil (5-FU) was capable of improving chemosensitivity in chemorefractory CRC cells, but a synergistic effect with 5-FU could only be demonstrated with celecoxib. To examine the potential clinical significance of these observations, in vivo studies were undertaken, which also showed that the greatest tumor regression was achieved in chemoresistant xenografts after chemotherapy in combination with celecoxib, but not aspirin. We also noted that these chemoresistant tumors with higher COX-2 expression had a more aggressive growth rate. Given the dramatic response to a combination of celecoxib + 5-FU, the possibility that celecoxib may modulate chemosensitivity as a result of its ability to inhibit MDR-1 was examined. In addition, assessment of a tissue microarray consisting of 130 cases of CRCs revealed that, in humans, higher COX-2 expression was associated with poorer survival with a 68% increased risk of mortality, indicating that COX-2 expression is a marker of poor clinical outcome. The findings of this study point to a potential benefit of combining COX-2 inhibitors with current regimens to achieve better response in the treatment of therapy-refractory CRC and in using COX-2 expression as a prognostic marker to help identify individuals who would benefit the greatest from closer follow-up and more aggressive therapy.

Renal function during rofecoxib therapy in patients with metastatic cancer: retrospective analysis of a prospective phase II trial

Background

Angiostatic/antiinflammatory therapy with COX-II inhibitors and pioglitazone seems to be a well tolerated and promising regimen in patients with metastatic cancer. COX-II inhibitors may have less gastrointestinal side effects than conventional non-steroidal antiinflammatory drugs, but their impact on renal function seems to be similar.

Methods

87 patients with metastatic/advanced cancer were treated up to 12 months (mean 19.5 weeks) with rofecoxib, pioglitazone and either capecitabine (group A with gastrointestinal and urological cancer, n = 50) or trofosfamide (group B with non-gastrointestinal/non-urological cancer, n = 37) and followed for further 6 months.

Results

Baseline serum creatinine concentration was 0.81 ± 0.28 mg/dl, and increased by about 0.15 mg/dl during months 1-3. Accordingly estimated glomerular filtration rate (eGFR) decreased from 90.3 ml/min ± 3.6 ml/min at baseline by about 10 ml/min during months 1-3. Renal function decreased in 75 patients (86%) in the first month (p < 0.0001). This decrease went along with clinical signs of volume expansion. Renal function tended to recover after discontinuation of the study medication.

Conclusions

Therapy with rofecoxib in an antiangiogenic/antiinflammatory setting results in a decrease of renal function in nearly every patient.

Trial registration number

German Clinical Trials Register DRKS: DRKS00000119

Non-Steroidal Anti-Inflammatory Drugs in the Carcinogenesis of the Gastrointestinal Tract

It is estimated that underlying infections and inflammatory responses are linked to 15–20% of all deaths from cancer worldwide. Inflammation is a physiologic process in response to tissue damage resulting from microbial pathogen infection, chemical irritation, and/or wounding. Tissues injured throughout the recruitment of inflammatory cells such as macrophages and neutrophils, generate a great amount of growth factors, cytokines, and reactive oxygen and nitrogen species that may cause DNA damage that in turn predisposes to the transformation from chronic inflammation to neoplasia. Cyclooxygenase (COX), playing a key role in cell homeostasis, angiogenesis and tumourigenesis, may represent the link between inflammation and cancer. Currently COX is becoming a pharmacological target for cancer prevention and treatment.

Double blind randomized phase II study with radiation+5-fluorouracil+/-celecoxib for resectable rectal cancer

PURPOSE

To assess the feasibility and efficacy of the COX-2 inhibitor celecoxib in conjunction with preoperative chemoradiation for patients with locally advanced rectal cancer in a double blind randomized phase II study.

MATERIALS AND METHODS

Thirty-five patients of the initially planned 80 patients with locally advanced rectal cancer were treated with preoperative radiation (45 Gy; 1.8 Gy/fraction, 5 days/week) combined with 5-fluorouracil (continuous infusion, 225 mg/m(2)/day) and celecoxib (2 x 400 mg/day) or placebo. Pathological response and toxicity of study treatment were evaluated, as well as expression of COX-2 and Ki67 in tumor tissue and IL-6 in plasma as possible molecular correlates and predictors of response to treatment.

RESULTS

Patients treated with celecoxib tended to show a better response (61%) when compared to those treated with placebo (35%), although not significant (p=0.13). T-downstaging and N-downstaging were also slightly higher with celecoxib. Plasma IL-6 levels and intratumoral COX2 or Ki67 were altered by chemoradiation, but were not further altered by celecoxib treatment and therefore not useful for prediction of treatment benefit. Celecoxib therapy in conjunction with chemoradiation was not associated with additional toxicity and seemed to help mitigate therapy-related pain.

CONCLUSIONS

Addition of celecoxib to preoperative chemoradiation is feasible for patients with locally advanced rectal cancer. To study the individual effect of COX-2 inhibitors on pathological response phase III studies are required.

Colonic treatments and targets: issues and opportunities

The colon provides a plethora of therapeutic opportunities. There are multiple disease targets, drug molecules, and colon-specific delivery systems to be explored. Clinical studies highlight the potential for systemic delivery via the colon, and the emerging data on the levels of cell membrane transporters and metabolic enzymes along the gut could prove advantageous for this. Often efflux transporters and metabolic enzyme levels are lower in the colon, suggesting a potential for improved bioavailability of drug substrates at this site. The locoregional distribution of multiple metabolic enzymes (including cytochromes), efflux transporters (including P-glycoprotein and breast cancer resistance proteins), and influx transporters (including the solute carrier family) along the intestine is summarized. Local delivery to the colonic mucosa remains a valuable therapeutic option. New therapies that target inflammatory mediators could improve the treatment of inflammatory bowel disease, and old and new anticancer molecules could, when delivered topically, prove to be beneficial adjuncts to the current systemic or surgical treatments. New issues such as pharmacogenomics, chronotherapeutics, and the delivery of prebiotics and probiotics are also discussed in this review. Targeting drugs to the colon utilizes various strategies, each with their advantages and flaws. The most promising systems are considered in the light of the physiological data which influence their in vivo behavior.

Immunotherapy for gastrointestinal cancer: current status and strategies for improving efficacy

BACKGROUND

Despite improvement in conventional strategies for treating gastrointestinal (GI) carcinoma, large numbers of patients still suffer from incurable or progressive disease.

OBJECTIVE

Here we consider the prospects for circumventing limitations and maximising the efficacy of different immunotherapies.

METHODS

We summarise different cancer vaccines and targeted drugs and highlight the scientific rationale of using immunotherapy for targeting GI cancers, in addition to the potential strategies for improving immunotherapeutic efficacy.

RESULTS/CONCLUSION

Many cancer vaccines and antibody-directed therapies have been tested in early phase clinical trials and demonstrated proof of concept and safety. As yet few have been properly evaluated for clinical efficacy; although adoptive transfer of tumour-associated-antigen-specific T cells has shown dramatic clinical responses in some patients. The recognition of a role for T regulatory cells in limiting anti-tumour immunity has provided momentum for developing strategies to over-ride such immunoinhibitory effects. There is some evidence that conventional therapies may work by influencing these negative factors and allowing expression of immune control mechanisms. An important developing area for clinical evaluation is the testing of combined conventional and immunotherapeutic modalities which may provide for synergy; thereby circumventing the limitations of individualised treatments and generating additional clinical benefits.

5-Lipoxygenase is coexpressed with Cox-2 in sporadic colorectal cancer: a correlation with advanced stage

PURPOSE

It has been extensively documented that the cyclooxygenase inducible form and 15-lipoxygenase are implicated in colorectal carcinogenesis. Nonetheless, the role of other enzymes involved in the arachidonic acid metabolism, such as 5-lipoxygenase, in colorectal neoplasms has not been fully ascertained. This study was designed to evaluate 5-lipoxygenase expression in sporadic colorectal adenocarcinomas by using immunohistochemistry and to analyze its potential correlations with clinicopathologic parameters and with cyclooxygenase-2 expression.

METHODS

Expression of 5-lipoxygenase and cyclooxygenase-2 were evaluated by immunohistochemistry in 50 surgically resected sporadic colorectal adenocarcinomas (28 male and 22 female patients age range, 47-88 (mean age, 69 +/- 8) years). The chi-squared and Spearman correlation tests were used to analyze correlations with clinicopathologic characteristics and to evaluate any relationships between expression of the two enzymes. P values <0.05 were considered statistically significant.

RESULTS

5-Lipooxygenase and cyclooxygenase-2 immunostaining was found in the cytoplasm of neoplastic cells in 41 (82 percent) and in 43 cases (86 percent), respectively. Spearman correlation test demonstrated a positive correlation in the expression of the two enzymes. A statistically significant correlation also was observed between 5-lipoxygenase expression and tumor stage and lymph node metastasis, whereas no significant correlations emerged regarding cyclooxygenase-2 expression and clinicopathologic parameters.

CONCLUSIONS

Our study demonstrates that 5-lipoxygenase is expressed in colorectal adenocarcinomas in association with cyclooxygenase-2 expression. Moreover, an elevated expression of this enzyme seems to be significantly correlated with tumor aggressiveness. Further studies would clarify the need for target therapies inhibiting both metabolic pathways in such tumors.

Cyclooxygenase in the treatment of glioma: its complex role in signal transduction

BACKGROUND

High-grade glioma remains one of the most difficult cancers to treat. Recent studies in oncology have identified a role of the ubiquitous enzyme, cyclooxygenase (Cox), especially cyclooxygenase-2 (COX-2) in cell proliferation, and its inhibition in cancer control, apoptosis, as well as synergy with other forms of therapy. The inhibitors of the Cox enzyme are well known as members of the nonsteroidal anti-inflammatory drug (NSAID) class of pharmaceuticals.

METHODS

In vitro and in vivo studies of different cancers expressing COX-2, including glioma studies, along with the few clinical trials that have been reported are reviewed to specifically identify the actions of these agents.

RESULTS

The anticancer effect of the COX-2 inhibitors may occur irrelevant of COX-2 expression, and it appears to be drug-specific, as well as dose-specific in different cancers. In combination with chemotherapeutic agents, the COX-2 inhibitors may have an additive, synergistic, or inhibitory effect on tumor growth.

CONCLUSIONS

As evaluations of this class of drugs begin in glioma, in vitro and in vivo data should be acquired to accurately predict which compounds will have an effect in controlling tumor growth and at which doses these should be used. The actual expression and inhibition of COX-2 may not always be relevant to the effects on tumor growth.

Synergistic antitumor effects of celecoxib with 5-fluorouracil depend on IFN-gamma

Cyclooxygenase-2 (COX-2) inhibitors are effective chemopreventive agents against colorectal cancers. For treatment of advanced cancers, combination of COX-2 inhibitors and chemotherapy has been attempted, but the results are still controversial. In the present study, the effects of the COX-2 inhibitor celecoxib on the anticancer potential of chemotherapy, and its mechanisms of action were investigated in point of the angiogenesis, using an advanced cancer model in mice. BALB/c mice were inoculated with colon 26 cells. After the allograft grew up to 5 mm in diameter, the animals received celecoxib, 5FU, or a combination of 5FU and celecoxib (5FU/celecoxib). After 21-days of the treatment, 5FU/celecoxib significantly inhibited the tumor growth and the tumor vessel density compared with the other groups. Celecoxib, 5FU or 5FU/celecoxib significantly suppressed the VEGF content in tumor tissues. 5FU/celecoxib also enhanced IFN-gamma levels in tumor tissue, which could be involved in the potent antitumor effects of 5FU/celecoxib. This hypothesis was proven, because in IFN-gamma knockout (IFN-gamma(-/-)) mice, the inhibitory effects of 5FU/celecoxib on angiogenesis and tumor growth were significantly impaired compared with that in wild type mice. These results suggest that celecoxib enhances the antitumor effect of 5FU against an advanced colon cancer model by suppressing angiogenesis. In addition to VEGF, IFN-gamma has pivotal roles in tumor suppression induced by celecoxib.

Efficacy and Patterns of Failure for Locally Advanced Cancer of the Cervix Treated With Celebrex (Celecoxib) and Chemoradiotherapy in RTOG 0128

PURPOSE

To determine the efficacy and patterns of initial failure for oral celecoxib, intravenous cisplatin, and 5-fluorouracil and concurrent pelvic radiotherapy in patients with locally advanced cancer of the cervix.

METHODS AND MATERIALS

Patients were treated with concurrent 5-fluorouracil and cisplatin chemotherapy and pelvic radiotherapy and brachytherapy. Celecoxib was prescribed at a dose of 400 mg twice daily for 1 year beginning on the first day of radiotherapy. The overall and disease-free survival rates were determined.

RESULTS

A total of 84 patients were accrued, of whom 78 were eligible. The estimated 2-year disease-free survival and overall survival rate was 69% and 83%, respectively. Of the 78 patients, 24 had treatment failure: 3 with persistent local disease, 9 local only, 2 regional, 4 distant, 1 regional and distant, 1 local and distant, and 2 with local, regional, and distant disease, and 1 had died of cervical cancer without a reported site of first failure and 1 without evidence of disease.

CONCLUSION

At 2 years, the estimated disease-free survival and overall survival rate for patients with advanced cervical cancer who underwent a combination of chemoradiotherapy and celecoxib treatment was 69% and 83%, respectively. Recurrent disease developed in 24 patients, and, of those patients, 18 had a component of locoregional failure as a site of first failure. Thus, locoregional control continues to be problematic after chemoradiotherapy as delivered in our study. The identification of more active biologically targeted therapies is warranted for the treatment of advanced cancer of the cervix.

A Phase II study of acute toxicity for Celebrex™ (celecoxib) and chemoradiation in patients with locally advanced cervical cancer: Primary endpoint analysis of RTOG 0128

PURPOSE

To determine treatment-related acute toxicity rates in patients with locally advanced cervical cancer treated by oral celecoxib, i.v. cisplatin and 5-FU, and concurrent pelvic radiation therapy.

METHODS AND MATERIALS

Eligible patients on this RTOG Phase I-II study for advanced cervix cancer included FIGO Stage IIB-IVA or patients with FIGO Stage IB through IIA with biopsy proven pelvic node metastases or tumor size > or =5 cm. Patients were treated with pelvic radiotherapy and brachytherapy. Celecoxib was prescribed at 400 mg twice daily beginning on day 1 for 1 year. Cisplatin (75 mg/m2) and 5-FU (1g/m2 for 4 days) were administered every 3 weeks times 3. The primary end point of the study was treatment related toxicity.

RESULTS

Between August 2001 and March 2004, 84 patients were accrued to the study and 77 patients were evaluable for toxicity. Regarding the primary end point, toxicities were observed in the following areas: blood/bone marrow (16), gastrointestinal (14), pain (7), renal/genitourinary (6), cardiovascular (3), hemorrhage (1), and neurologic (1). For the first 75 evaluable patients, a toxicity failure was identified in 36 patients for a rate of 48%.

CONCLUSIONS

Celecoxib at 400 mg twice daily together with concurrent cisplatin and 5-FU and pelvic radiotherapy has a high incidence of acute toxicities. The most frequent toxicities were hematologic. Albeit, the toxicity was deemed excessive in this trial, the rate of toxicities was not too different compared to other recent experiences with concurrent chemoradiation for advanced cervix cancer.

Non-steroidal anti-inflammatory drugs to potentiate chemotherapy effects: from lab to clinic

Most solid tumors express the cyclooxygenase-2 (COX-2) protein, a target of NSAIDs. COX-2 overexpression in tumorsis considered a predictor of more advanced stage disease and of worse prognosis in a number of studies investigating solid malignancies. Therefore, NSAIDs are evaluated as anti-cancer drugs. NSAIDs inhibit proliferation, invasiveness of tumors, and angiogenesis and overcome apoptosis resistance in a COX-2 dependent and independent manner. This review will focus on the rationale behind NSAIDs, including selective COX-2 inhibitors, in combination with conventional chemotherapeutic drugs or novel molecular targeted drugs. Studies investigating anti-cancer effects of NSAIDs on cell lines and xenograft models have shown modulation of the Akt, NF-kappaB, tyrosine kinase and the death receptor-mediated apoptosis pathways. COX-2 expression in tumors is not yet used as biomarker in the clinic. Despite the increased risk on cardiovascular toxicity induced by selective COX-2 inhibitors, several ongoing clinical trials are still investigating the therapeutic benefits of NSAIDs in oncology. The anti-tumor effects in these trials balanced with the side effects data will define the precise role of selective COX-2 inhibitors in the treatment of cancer patients.

Chemoprevention of colorectal cancer with nonsteroidal anti-inflammatory drugs

Colorectal carcinoma is one of the commonest solid organ tumors in the world and its prevalence appears to be increasing in Asia. Recently, there has been much interest in various chemotherapeutic agents for the management of this condition, in particular nonsteroidal anti-inflammatory drugs (NSAIDs). There is a large amount of data that suggest traditional NSAIDs, as well as the new cyclooxygenase (COX)-2 selective inhibitors such as rofecoxib and celecoxib, have a role in the setting of primary and secondary prevention, and adjuvant therapy of both sporadic colorectal carcinoma and familial adenomatous polyposis. This review examines some of this data, as well as the potential problems and limitations of using these agents, particularly in light of the recent withdrawal of rofecoxib.

Cyclooxygenase-2 as a target for anticancer drug development

The two isoforms cyclooxygenase-1 and -2 catalyze the initial step in the formation of prostaglandins in a variety of pathophysiological processes. More recently their role in carcinogenesis has become more evident. They seem to influence apoptosis, angiogenesis, and invasion, and play a role in the production of carcinogens. Usually, a high level of COX-2 expression is found in cancer cells. However, low COX-2 expression is observed in some cancers like prostate or breast cancer. This phenomenon is quite surprising and should influence on clinical trial designs. Large epidemiological trials studying users and non-users of aspirin have shown that cyclooxygenase (COX) inhibitors and non-steroidal anti-inflammatory drugs (NSAIDs) could be of benefit against the development and growth of malignancies. Moreover, clinical trials in patients with familial adenomatosis polyposis syndrome have shown too the efficacy of non-selective COX inhibitors and recently also of selective COX-2 inhibitors in the reduction of the number and the size of colorectal polyps. However, a primary chemopreventive effect has not been demonstrated yet. NSAIDs are also supposed to have a preventive and growth inhibitory effect in extra-colonic epithelial malignancies. Several preclinical studies show promising results with combination treatments of either chemotherapy or radiotherapy with COX inhibitors. Preclinical studies with the simultaneous use of inhibitors of the epidermal growth factor receptor and COX-2 inhibitors have shown also promising results. Encouraging results with the first clinical trials combining chemotherapy with COX-2 inhibitors in patients with cancer in the advanced and neoadjuvant setting have recently been reported. However, NSAIDs effects in cancer cells are mediated not only by COX enzymes but also by interactions with downstream effectors of COX-2. Hence, we can state that targeting the COX-2 pathway is a promising strategy in the prevention and treatment of solid tumors. Ongoing trials are expected to answer - at least partly - the remaining questions concerning COX-2 and cancer.

Cyclooxygenase-2 (COX-2)-independent anticarcinogenic effects of selective COX-2 inhibitors

Nonsteroidal antiinflammatory drugs (NSAIDs) appear to reduce the risk of developing cancer. One mechanism through which NSAIDs act to reduce carcinogenesis is to inhibit the activity of cyclooxygenase-2 (COX-2), an enzyme that is overexpressed in various cancer tissues. Overexpression of COX-2 increases cell proliferation and inhibits apoptosis. However, selective COX-2 inhibitors can also act through COX-independent mechanisms. In this review, we describe the COX-2-independent molecular targets of these COX-2 inhibitors and discuss how these targets may be involved in the anticarcinogenic activities of these selective COX-2 inhibitors. We also compare the concentrations of these inhibitors used in in vitro and in vivo experiments and discuss the implications of the in vitro studies for clinical management of cancer with these drugs.

FOLFIRI with or without celecoxib in advanced colorectal cancer: a randomized phase II study of the Gruppo Oncologico dell'Italia Meridionale (GOIM)

BACKGROUND

The aim of the study was to verify the efficacy and safety of the addition of celecoxib to FOLFIRI combination therapy in patients affected by advanced colorectal cancer.

PATIENTS AND METHODS

Eighty-one chemotherapy-naïve patients entered in this randomized phase II trial of the GOIM (protocol no. 2301). Patients were randomized to receive FOLFIRI regimen (arm A): irinotecan 180 mg/m(2) on day 1 with LV5FU2 regimen (LV at 100 mg/m(2) administered as a 2-h infusion before FU at 400 mg/m(2) as an intravenous bolus injection, and FU at 600 mg/m(2) as a 22-h infusion immediately after 5-FU bolus injection on day 1 and 2); or FOLFIRI plus celecoxib 400 mg twice daily for 14 days (arm B). Both treatments were repeated every 2 weeks.

RESULTS

Seventy-seven patients (38 in arm A and 39 in arm B) were evaluable for response. The overall response rate was 41% in arm A (95% CI 27% to 57%) and 35% in arm B (95% CI 20% to 50%). When only assessable patients were analyzed, overall response rate was 45% in arm A (95% CI 29% to 61%) and 36% in arm B (95% CI 21% to 51%). Median time to progression, median duration of response and survival were, respectively, 8 months, 9 months and 16 months in arm A, and 7 months, 9 months and 19 months in arm B. All patients were evaluable for toxicity, which was globally mild in both arms; grade 3-4 toxicity was uncommon, and gastrointestinal disturbances were the most common.

CONCLUSIONS

FOLFIRI regimen is effective and well-tolerated as a first-line treatment in patients with advanced colorectal cancer. The addition of celecoxib to FOLFIRI regimen does not improve results.

Retrospective Study of Capecitabine and Celecoxib In Metastatic Colorectal Cancer

OBJECTIVE

COX-2 activation may mediate capecitabine induced toxicities, eg, hand-foot syndrome (HFS) and colorectal cancer progression, both of which may be improved by concurrent celecoxib.

PATIENTS AND METHODS

From October 2000 to December 2003, 66 patients with metastatic colorectal cancer received concurrent capecitabine at 1000 mg/m/d b.i.d. and celecoxib at 200 mg b.i.d. (XCEL). Twenty-four patients were chemo-naive, 42 patients were second-line; while 34 had XCEL with radiation.

RESULTS

The median duration of XCEL was 7.2 months (range, 1.5-38 months). Ninety percent of Grade 2/3 HFS (17%) occurred after 6 months and incidence of grade 3/4 diarrheas was 8%. The overall response rate was 38% (95% confidence interval [CI], 26-51%), with 11 patients (17%) achieving complete responses and 2 patients (3%) with near complete responses. Six patients (9%) become resectable after sustaining treatment response. The median progression-free survival (PFS) and overall survival (OS) was 8.3 months (95% CI, 7.0-11.0 months) and 22 months (95% CI, 17.8-31.5 months), respectively. Improved median PFS of 14.5 months (P = 0.0001) and OS of 31.5 months (P = 0.005) were noted in patients with normal lactate dehydrogenase (LDH) levels (n = 37) than patients with high levels of LDH (n = 29).

CONCLUSIONS

XCEL integrating radiation may improve response rate and survival and reduce toxicities, notably HFS for patients with metastatic colorectal cancer, leading to a randomized phase III study.

Beyond 5-fluorouracil: new horizons in systemic therapy for advanced colorectal cancer

Worldwide, colorectal cancer is a common cancer and a major cause of morbidity and mortality. Patients frequently present with, or later develop, metastatic disease. Median survival with supportive care alone is approximately 6 - 8 months. However, a number of recent developments have greatly increased the range of therapeutic options, improving median survival to > 20 months. Cytotoxic agents such as capecitabine, irinotecan and oxaliplatin are now established treatment strategies. In parallel, an improved understanding of tumour biology has led to the development of non-cytotoxic targeted therapies. Examples include bevacizumab (targeting tumour angiogenesis) and cetuximab (targeting the epidermal growth factor receptor). These agents have recently been incorporated into standard management. This paper reviews these and other advances in the care of patients with advanced colorectal cancer and discusses a number of agents that are currently under development.

Cyclooxygenase-2 inhibition sensitizes human colon carcinoma cells to TRAIL-induced apoptosis through clustering of DR5 and concentrating death-inducing signaling complex components into ceramide-enriched caveolae

Cyclooxygenase-2 (COX-2) is up-regulated in human colon carcinomas, and its inhibition is associated with a reduction in tumorigenesis and a promotion of apoptosis. However, the mechanisms responsible for the antitumor effects of COX-2 inhibitors and how COX-2 modulates apoptotic signaling have not been clearly defined. We have shown that COX-2 inhibition sensitizes human colon carcinoma cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis by inducing clustering of the TRAIL receptor DR5 at the cell surface and the redistribution of the death-inducing signaling complex components (DR5, FADD, and procaspase-8) into cholesterol-rich and ceramide-rich domains known as caveolae. This process requires the accumulation of arachidonic acid and sequential activation of acid sphingomyelinase for the generation of ceramide within the plasma membrane outer leaflet. The current study highlights a novel mechanism to circumvent colorectal carcinoma cell resistance to TRAIL-mediated apoptosis using COX-2 inhibitors to manipulate the lipid metabolism within the plasma membrane.

Non-COX-2 targets and cancer: Expanding the molecular target repertoire of chemoprevention

Chemoprevention represents a highly promising approach for the control of cancer. That nonsteroidal anti-inflammatory drugs (NSAIDs) prevent colon and other cancers has led to novel approaches to cancer prevention. The known inhibitory effect of NSAIDs on the eicosanoid pathway prompted mechanistic and drug development work focusing on cyclooxygenase (COX), culminating in clinical trials of cyclooxygenase 2 (COX-2) inhibitors for cancer prevention or treatment. However, two COX-2 inhibitors have been withdrawn due to side effects. Here we review several pathways of the eicosanoid cascade that are relevant to cancer; summarize the evidence regarding the role of COX-2 as a target for cancer prevention; and discuss several of the molecular targets that may mediate the chemopreventive effect of NSAIDs. The clinically modest results obtained to date with COX-2 specific inhibitors used in cancer prevention; the multiple COX-2-independent targets of both NSAIDs and COX-2 inhibitors; and the limitations of some COX-2 inhibitors indicate that exploiting these (non-COX-2) molecular targets will likely yield effective new approaches for cancer chemoprevention.

COX-2: a molecular target for colorectal cancer prevention

Cyclooxygenase (COX), a key enzyme in the prostanoid biosynthetic pathway, has received considerable attention due to its role in human cancers. Observational and randomized controlled studies in many different population cohorts and settings have demonstrated protective effects of nonsteroidal anti-inflammatory drugs (NSAIDs; the inhibitors of COX activity) for colorectal cancers (CRCs). COX-2, the inducible isoform of cyclooxygenase, is overexpressed in early and advanced CRC tissues, which portends a poor prognosis. Experimental studies have thus identified important mechanisms and pathways by which COX-2 plays an important role in carcinogenesis. Selective COX-2 inhibitors have been approved for use as adjunctive therapy for patients with familial polyposis. The role of COX-2 inhibitors is currently being evaluated for use in wider populations.

Cancer prevention: a new era beyond cyclooxygenase-2

The seminal epidemiological observation that nonsteroidal anti-inflammatory drugs (NSAIDs) prevent colon and possibly other cancers has spurred novel approaches to cancer prevention. The known inhibitory effect of NSAIDs on the eicosanoid pathway prompted studies focusing on cyclooxygenase (COX) and its products. The increased prostaglandin E2 levels and the overexpression of COX-2 in colon and many other cancers provided the rationale for clinical trials with COX-2 inhibitors for cancer prevention or treatment. Their efficacy in the prevention of sporadic colon and other cancers remains unknown; one COX-2 inhibitor has been withdrawn because of side effects, and there are concerns about whether these effects are class-specific. There is evidence to suggest that COX-2 may not be the only or ideal eicosanoid pathway target for cancer prevention. Six sets of observations support this notion: the relatively late induction of COX-2 during carcinogenesis; the finding that NSAIDs may not require inhibition of COX-2 for their effect; the modest effect of coxibs in cancer prevention; that currently available coxibs have multiple non-COX-2 effects that may account for at least some of their efficacy; the possibility that concurrent inhibition of COX-2 in non-neoplastic cells may be harmful; and the possibility that COX-2 inhibition may modulate alternative eicosanoid pathways in a way that promotes carcinogenesis. Given the limitations of COX-2-specific inhibitors and the biological evidence mentioned above, we suggest that targets other than COX-2 should be pursued as alternative or complementary approaches to cancer prevention.

COX-2 inhibition in cancer therapeutics: a field of controversy or a magic bullet?

Carcinogenesis is a multistep process of long-term accumulation of genetic and epigenetic aberrations at the molecular level. Understanding the mechanisms underlying carcinogenesis could further provide insights for rationally designed new therapeutic strategies for cancer prevention and treatment. Epidemiological and experimental evidence supports the preventative effect of non-steroidal anti-inflammatory drugs (NSAIDs) regarding cancer development. NSAIDs inhibit cyclooxygenase (COX) activity, thus blocking the endogenous prostaglandin production. COX-2 is a key isoenzyme in this biochemical cascade and is inducible by various oncogenic stimuli. A large volume of research data has shown that COX-2 is often upregulated in many malignant tumours, rendering it an attractive candidate target for cancer therapeutics. Various possible direct mechanisms for COX-2 implication in carcinogenesis have been suggested, whilst intense interest has recently been focused on COX-2-independent effects of NSAIDs. Several COX-2-selective inhibitors are currently under evaluation in preclinical and clinical studies, either as single agents or in combination with conventional chemotherapy, radiotherapy and other new molecularly-targeted compounds, with promising results. This article critically reviews already published data on COX-2-selective inhibitors that have been tested in cancer clinical trials, highlights ongoing research and considers the future perspectives of this novel class of agents.

Cyclooxygenase-2 inhibition in colorectal cancer: Boom or bust?

Currently, combination chemotherapy represents the standard of care treatment for patients with metastatic colorectal cancer in the United States. Despite recent improvements with the addition of biologic agents, novel treatment approaches are needed to further benefit patients. Cyclooxygenase (COX)-2 inhibition represents one such possibility. COX-2 is highly expressed in colorectal tumor neovasculature and nodal and liver metastases, and expression of COX-2 correlates with tumor stage and patient survival in selected series. COX-2 may be related to colorectal cancer development and propagation through multiple mechanisms, including stimulation of growth, migration, and invasiveness, resistance to apoptosis, and enhancement of angiogenesis. Epidemiologic data suggest nonsteroidal anti-inflammatory drugs (NSAIDs) might prevent development of colorectal cancers, and preclinical data suggest selective COX-2 inhibitors might be additive or synergistic with specific chemotherapeutic agents used in the treatment of colorectal cancer. Despite the lack of published phase I data and the limited, preliminary results of phase II studies, combinations of celecoxib and standard colorectal cancer chemotherapy have entered randomized trials. It is too early to definitively state whether COX-2 inhibition represents a major breakthrough in the treatment of colorectal cancer. Pending the results of ongoing and planned phase III studies, use of COX-2 inhibitors as single agents or incorporation of COX-2 inhibition into combined modality therapy of colorectal cancer should be limited to the setting of clinical trials.

Cyclooxygenase-2 Is a Target of KRASD12, Which Facilitates the Outgrowth of Murine C26 Colorectal Liver Metastases

Purpose: Mutational activation of the KRAS oncogene and overexpression of cyclooxygenase-2 (COX-2) contribute to colorectal carcinoma (CRC) development, but the relationship between these two events is unclear. This study was designed to clarify that relationship and to assess the contribution of KRAS-dependent COX-2 to the seeding of CRC cells in the liver and to their outgrowth as liver metastases in an experimental mouse model.

Experimental Design: The effect of RNA interference–mediated KRAS knockdown on COX-2 expression and activity was tested in murine C26 CRC cells. The contribution of KRAS-dependent COX-2 to early metastatic tumor cell seeding (by intravital microscopy) and outgrowth of metastases in the liver (by bioluminescence imaging) was studied by using parecoxib, a novel and highly selective liver-activated COX-2 inhibitor. Intratumoral cell proliferation, apoptosis, and tumor-associated angiogenesis were assessed by immunohistochemistry on liver tissue sections.

Results: Stable knockdown of mutant KRASD12 in murine C26 CRC cells by RNA interference lead to a dramatic reduction of COX-2 synthesis and prostaglandin E2 production. Inhibition of host or tumor cell COX-2 activity had no effect on early metastatic cell seeding in the liver but greatly reduced intrahepatic tumor cell proliferation and the rate of liver metastasis outgrowth. COX-2 inhibition had no effect on early tumor vascularization or on tumor cell apoptosis.

Conclusions: The high levels of COX-2 enzyme and prostaglandin production in C26 CRC cells are primarily caused by the presence of endogenous mutant KRASD12. Furthermore, COX-2 inhibition affects the tumoral rather than the vascular compartment during the early stages of C26 liver metastasis outgrowth.

A phase I study of 5-fluorouracil, leucovorin, and celecoxib in patients with incurable colorectal cancer

A phase I study of fixed-dose 5-fluorouracil (FU) and leucovorin (LCV), with excalating doses of the selective cyclooxygenase-2 (COX-2) inhibitor celecoxib, was conducted in 16 patients with advanced colorectal adenocarcinoma. At doses typically used to treat arthritis patients (100-200 mg po BID), celecoxib did not increase toxicities expected from the chemotherapy alone. 5-FU and leucovorin did not affect COX-2 inhibition by celecoxib. Preliminary data suggest it is safe to combine celecoxib with standard chemotherapeutic agents, in treatment of patients with colorectal cancer.

Cyclooxygenase-2 Expression

PURPOSE

Recent studies have shown that cyclooxygenase (Cox)-2 may be involved in colorectal carcinogenesis. We aimed to determine whether Cox-2 expression in itself can predict outcome of colorectal cancer patient after surgery. In addition, the expression of Cox-1 was also evaluated.

EXPERIMENTAL DESIGN

Tissue samples of primary and secondary tumors from 288 patients undergoing surgical resections for colorectal adenocarcinoma were immunohistochemically examined for Cox-2 and Cox-1 expressions. The specimens were graded based on the intensity and extent of staining; then, the correlations between Cox-2 and Cox-1 expressions with clinicopathologic parameters and survival time were analyzed.

RESULTS

Expression of Cox-2 was positive in 70.8% of primary tumor, 92.0% of lymph node metastases, 100.0% of hepatic metastases, and was significantly associated with tumor size, depth of invasion, lymph node metastasis, vessels invasion, stage and recurrence. In contrast, Cox-1 was positive in 42.7% of primary tumor, 84.0% of lymph node metastases, 37.5% hepatic metastases, and was associated with only tumor size. Patients with Cox-2-positive tumors had a significant shorter survival time than those with negative tumors did (P = 0.0006 by log-rank test); and, in a multivariate analysis, Cox-2 was an independent prognostic factor (P = 0.0103; relative risk 4.114; 95% confidence interval, 1.397-12.120). Cox-1 status had no statistically effect on patient survival time.

CONCLUSIONS

Elevated Cox-2 expression, but not that of Cox-1, was significantly associated with reduced survival and recognized as an independent prognostic factor in our cohort of colorectal cancer patients.

Cyclooxygenases: new forms, new inhibitors, and lessons from the clinic

The beneficial actions of nonsteroidal anti-inflammatory drugs (NSAIDs) have been linked to their ability to inhibit inducible COX-2 at sites of inflammation, and their side effects (e.g., gastric damage) to inhibition of constitutive COX-1. Selective inhibitors of COX-2, such as celecoxib, etoricoxib, lumiracoxib, rofecoxib, and valdecoxib have been developed and the greatest recent growth in our knowledge in this area has been come from the clinical use of these compounds. Although clinical data indicate that COX-2 selectivity is associated with a reduction in severe gastrointestinal events, they also reveal there are roles for constitutive COX-2 within tissues such as the brain, kidney, pancreas, intestine, and blood vessels. We now better understand the roles of COX-1 and COX-2 in functions as disparate as the perception of pain and the progression of cancers. Clinical use of COX-2-selective compounds has ignited strong debates regarding potential side effects, most notably those within the cardiovascular system such as myocardial infarctions, strokes, and elevation in blood pressure. This review will discuss how the latest studies help us understand the roles of COX-1 and COX-2 and what clinically proven benefits the newer generation of COX-2-selective inhibitors offer

Cyclooxygenase-2 and its role in colorectal cancer development

Cyclooxygenase 2 (COX-2), also called prostaglandin endoperoxide synthase 2, is involved in colorectal tumor development. This review deals with particular questions raised in this field such as the mechanisms of COX-2 related tumor promotion, the role of the different types of cells (epithelial and interstitial) expressing COX-2, the factors that trigger COX-2 induction, and the clinical potential of selective COX-2 inhibitors to treat or prevent colorectal tumors. Several mechanisms of COX-2 related tumor promotion have been identified. Some are dependent on prostaglandin E(2) production (such as induction of cell proliferation, angiogenenis or local immunosuppression, inhibition of apoptosis, increase in cell motility) and others are not (such as carcinogen activation or malondialdehyde production). COX-2 expression has been demonstrated in epithelial cells of colorectal cancers and adenomas and also in interstitial cells. These cells correspond to macrophages and/or fibroblasts and endothelial cells. COX-2 expression in these interstitial cells participates in tumor development. Factors or events that trigger COX-2 expression include oncogene activation, antioncogene inactivation, cytokines, growth factors, some fatty acids, bile salts, and mucins. Finally, selective COX-2 inhibitors may be effective in preventing or treating colorectal adenomas or carcinomas. However, their real efficiency and the cost/benefit balance are currently evaluated, and no definite conclusion can be made at the moment.

Sequence-dependent effect of a cyclooxygenase-2 inhibitor on topoisomerase I inhibitor and 5-fluorouracil-induced cytotoxicity of colon cancer cells

Selective cyclooxygenase-2 (COX-2) inhibitors have been found to induce anti-proliferative and apoptotic activity in many cancer cells. However, interaction between COX-2 inhibitors and other chemotherapeutic agents remains to be determined. We investigated the interactive effects of a selective COX-2 inhibitor, etodolac, in combination with 5-fluorouracil (5-FU) or SN-38 (active metabolite of irinotecan) on colon cancer cell lines, HT29 and SW620, in simultaneous and sequential administration schedules. Isobologram analysis demonstrated that etodolac in combination with 5-FU or SN-38 according to a simultaneous schedule resulted in only an additive effect; however, synergism was achieved in a sequential schedule. Apoptosis induction in both cell lines was also significantly increased after sequential treatment with etodolac followed by either 5-FU or SN-38 compared to that after simultaneous treatment with etodolac and either 5-FU or SN-38. Our study suggests apoptosis-inducing synergism resulted from administration of etodolac and either 5-FU or SN-38 sequentially, but not simultaneously.

The effects of Nimesulide combined with cisplatin on lung cancer

To study the effects of cyclooxygenase 2 selective inhibitor Nimesulide (NIM) combined with Cisplatin (DDP) on human lung cancer and the possible mechanisms, the proliferation and apoptosis of human lung cancer cell line A549 were evaluated by MTT reduction assay and flow cytometry respectively. The inhibitory effect on neoplasia in vivo was tested on nude mice subcutaneously implanted tumor. Our results showed that NIM and DDP could inhibit A549 cell proliferation in a concentration-dependent pattern; this action was enhanced when NIM (25 micromol/L) was given in combination with DDP and they worked in a synergistic or additive pattern as DDP concentration > or = 1 microg/ml. NIM and DDP could induce A549 cells apoptosis and the action was augmented when used in combination (P<0.01). NIM and DDP could inhibit the growth of subcutaneously implanted tumors on nude mice (P<0.05, P<0.01) and the inhibitory rate of NIM combined with DDP was significantly higher than that of NIM or DDP group (P<0.01, P<0.01). It is concluded that combined use of NIM and DDP has significant synergistic antitumor effects on lung cancer cell line A549 and in animals in vivo. The synergy may be achieved by growth inhibition and apoptosis induction.