Enhancement of tumor response to gamma-radiation by an inhibitor of cyclooxygenase-2 enzyme

Cyclooxygenase-2 expression correlates with diminished survival in invasive breast cancer treated with mastectomy and radiotherapy

PURPOSE

To evaluate the relationship between cyclooxygenase-2 (COX-2) expression and pathologic features and outcome in invasive breast cancer.

METHODS AND MATERIALS

Formalin-fixed, paraffin-embedded tumor specimens from 23 women with invasive breast cancer were stained for COX-2 expression. All women underwent mastectomy and locoregional radiotherapy. The distribution (percentage of positive staining cells) and intensity of COX-2 expression within the tumor cells were compared with clinical factors, including stage, grade, lymph node involvement, and outcome.

RESULTS

For invasive breast cancer, the distribution and intensity of COX-2 tumor expression correlated significantly with diminished overall survival. The 5-year overall survival rate was 100% for patients with <75% of breast cancer cells expressing COX-2 compared with 49% for patients with > or =75% (p = 0.044). The 5-year overall survival rate was 100% for patients with COX-2 intensity <80 compared with 60% for patients with COX-2 intensity > or =80 (p = 0.018). The percentage and intensity of COX-2 expression also correlated significantly with disease-free survival. The percentage of cells expressing COX-2 was significantly greater in women <40 years old than in women > or =40 years old (81% vs. 59%, respectively, p = 0.04).

CONCLUSION

Both the distribution and the intensity of COX-2 expression correlated significantly with disease-free and overall survival in patients with invasive breast cancer. Younger patients with invasive breast cancer may have a greater percentage of COX-2 expression in their tumors.

The eicosanoid cascade: possible role in gliomas and meningiomas

Eicosanoids constitute a large family of biologically active lipid mediators that are produced by two enzyme classes, cyclooxygenases (COX-1 and COX-2) and lipoxygenases (5-LO, 12-LO, and 15-LO). Increasing evidence suggests that in addition to a variety of epithelial malignancies, the two most common types of human brain tumour, gliomas and meningiomas, aberrantly overexpress eicosanoid producing enzymes and release a spectrum of eicosanoids that may promote tumorigenesis and the development of peritumorous brain oedema. Glioma and meningioma cells are killed in vitro and in animal models when exposed to COX-2 and 5-LO inhibitors, and their effectiveness is under investigation in clinical trials for treatment of patients with malignant brain tumours. However, despite research into the role of the eicosanoid cascade in the tumorigenesis of human brain tumours, many important questions remain unanswered. Current and newer agents that specifically target key players of the eicosanoid cascade could change the approach to treating brain tumours, because their benefits may lie in their synergism with conventional cytotoxic treatments and/or with other novel agents targeted against other procarcinogenic pathways.

Increased cyclooxygenase-2 (COX-2): a potential role in the pathogenesis of lymphoma

B cell lymphomas are a diverse group of clinicopathologic diseases with an increasing incidence. As with other malignancies, the accumulation of genetic abnormalities are required for malignant transformation of human lymphocytes. Cyclooxygenase-2 (COX-2) is a key biosynthetic enzyme in prostaglandin synthesis and has been implicated in the pathogenesis of numerous malignancies including colon, breast, and lung cancer. There is little data on the potential role of COX-2 in lymphoma pathogenesis. In this study, several B lymphoma cell lines and primary B cells obtained from normal volunteer controls were examined for COX-2 protein expression. Immunoblot analysis demonstrated between an approximately 2.2-4.3-fold increase in COX-2 protein expression relative to primary B cells in all lymphoma cell lines examined. Increased COX-2 phosphorylation was found in the BJAB, BL41, and Raji cells whereas the levels in Daudi, Namalwa, and Ramos did not differ from that of primary B cells. Treatment with 25-100 microM celecoxib (CEL) resulted in decreased proliferation as measured by [3H]thymidine in all cell lines examined, and the effect was dose-dependent, and not significantly enhanced by chlorambucil (CHL). The effect of COX-2 inhibition on apoptosis in lymphoma cells was examined and revealed apoptotic induction of greater than 85% in all cell lines examined at 50 microM celecoxib. The pro-apoptotic effect was dose-dependent, and was not significantly enhanced by chlorambucil. Examination of apoptosis-related proteins by immunoblot analysis revealed levels of BCL-2, BCL-X(L), and Bax to be unaffected by celecoxib. In contrast, levels of Akt, MCL-1, and phosphorylated SAP-kinase were all decreased after incubation with 50 microM celecoxib. These findings suggest that increased COX-2 expression and activity, contributes to the pathogenesis of B cell lymphomas and point to a possible role for COX-2 inhibition in their treatment.

Improvement strategies for molecular targeting: cyclooxygenase-2 inhibitors as radiosensitizers for non-small cell lung cancer

Cyclooxygenase-2 (COX-2) is an enzyme involved in prostaglandin production in pathologic states such as inflammatory processes and cancer. The enzyme is often overexpressed in premalignant lesions and various cancers, including cancer of the lung. Inhibition of this enzyme with selective COX-2 inhibitors was found to enhance tumor response to radiation in preclinical studies, suggesting that these agents can improve the response of various cancers to radiotherapy. On the basis of these preclinical findings, we initiated clinical trials of the combination of celecoxib, a selective COX-2 inhibitor, with radiotherapy in patients with lung cancer. Here we discuss the rationale for using selective COX-2 inhibitors and describe current clinical protocols and the initial findings.

NS 398 radiosensitizes an HNSCC cell line by possibly inhibiting radiation-induced expression of COX-2

PURPOSE

Cyclooxygenase-2 (COX-2) protein is frequently elevated in squamous cell carcinoma of the head and neck (HNSCC). The aim of this study was to determine if COX-2 inhibitors have radiosensitizing effects in HNSCC and understand the mechanism by which this occurs.

MATERIALS AND METHODS

The radiosensitizing effects of a selective COX-2 inhibitor, NS398, on a HNSCC cell line HEp3, were determined using clonogenic survival assay. Cells were pretreated with the dose of NS398 at which 50% growth inhibition occurred (IC(50)) and then irradiated. COX-2 protein and mRNA were then determined in the presence and absence of NS398.

RESULTS

NS398 significantly decreased (p < 0.0001) the calculated survival fraction (SF) for all radiation doses (0.79 to 0.41 at 2 Gy). A significant increase in COX-2 protein of 2.8 fold for 2 Gy and 3.5 fold for 6 Gy was noted 48 h after radiation. Interestingly, the upregulation of COX-2 protein with radiation was suppressed when cells were pretreated with NS398. Quantitative reverse transcriptase polymerase chain reaction showed no significant corresponding increase in COX-2 mRNA at 48 h with ionizing radiation.

CONCLUSIONS

The radiosensitizing effect of NS398 could be due to inhibition of radiation-induced COX-2 upregulation by this drug. NS398, known as an inhibitor of COX-2 enzyme activity, down-regulated COX-2 protein expression, which may indicate that NS398 can act upstream of COX-2, and this change appears to be post-transcriptional.

Improvement in efficacy of chemoradiotherapy by addition of an antiangiogenic agent in a murine tumor model

BACKGROUND

Chemoradiotherapy improves survival for some cancer patients. Methods of enhancing treatment response would further enhance survival rates. The effect of the addition of an antiangiogenic agent to a chemoradiotherapy regime has not previously been examined.

MATERIALS AND METHODS

C57B16 mice were inoculated with 1 x 10(6) Lewis lung carcinoma cells into the flank and randomized to 1 of 10 treatment groups when tumor volume approached 1000 mm(3). Animals received combinations of standard doses of intraperitoneal cisplatin, 5-fluorouracil, and the antiangiogenic agent genistein, together with 10 or 20 Gy of external beam radiotherapy. Animals were sacrificed at day 6 when tumor volume, microvessel density, and serum VEGF were determined.

RESULTS

Mean (SEM) tumor volume in the chemoradiotherapy group was 762 (212) mm(3) versus 565 (79) mm(3) in the chemoradiotherapy plus genistein group (P = 0.04, unpaired t-test). The addition of genistein produced a significant reduction in tumor microvessel density (P = 0.01) as well as serum VEGF levels (P < 0.05) compared to those animals receiving chemoradiation alone.

CONCLUSIONS

This study provides proof of principle that chemoradiation can be enhanced by the addition of an antiangiogenic agent to the regime and suggests that further examination of such regimes is warranted.

Cyclooxygenase-2 inhibitor NS398 enhances antitumor effect of irradiation on hormone refractory human prostate carcinoma cells

PURPOSE

We examined the potential therapeutic effect of NS398, a selective cyclooxygenase-2 (COX-2) inhibitor, combined with irradiation on human prostate adenocarcinoma DU145 cells.

MATERIALS AND METHODS

The effect on tumor growth, proliferation testing and clonogenic survival was determined to evaluate its antitumor effect when exposed to NS398 or combined with irradiation. Immunoblotting analyses were done to detect the expression of COX-2, nuclear factor-kappaB p50 and Rel A p65 because evidence suggested a biological association of COX-2 with alterations in these markers. Reverse transcriptase-polymerase chain reaction was also performed to show its effect on the transcription level of COX-2.

RESULTS

Exposure of DU145 cells to NS398 alone suppressed proliferation in a dose and time dependent manner. Examination of the NS398 effect on the radiation response showed marked enhancement of radiosensitivity. Western blot indicated that NS398 down-regulated the expression of COX-2, nuclear factor-kappaB, p50 and Rel A p65, whereas the effect was more pronounced when combined with irradiation. Reverse transcriptase-polymerase chain reaction showed that the NS398 antitumor effect was associated with COX-2 transcription inhibition. Importantly COX-2 expression was enhanced by irradiation but this phenomenon was abolished when cells were exposed to NS398. Inhibition of tumor growth in animal model was observed when mice were treated with NS398 alone and irradiation alone, and this effect was maximal when treated with NS398 and irradiation.

CONCLUSIONS

These results suggest that NS398 could be used as a potential therapeutic agent combined with irradiation for prostate adenocarcinoma.

COX‐2‐dependent stabilization of survivin in non‐small cell lung cancer

Elevated tumor cyclooxygenase 2 (COX-2) expression is associated with increased angiogenesis, tumor invasion and promotion of tumor cell resistance to apoptosis. The mechanism(s) by which COX-2 exerts its cytoprotective effects are not completely understood but may be due to an imbalance of pro- and anti-apoptotic gene expression. To analyze COX-2-dependent gene expression and apoptosis, we created cell lines constitutively expressing COX-2 cDNA in sense and antisense orientations. Whereas COX-2 sense cells have significantly heightened resistance to radiation and drug-induced apoptosis, COX-2 antisense cells are highly sensitive to apoptosis induction. We found that the expression of the anti-apoptotic protein survivin correlated positively with COX-2 expression. A COX-2-dependent modulation of survivin ubiquitination led to its stabilization in COX-2 overexpressing cells, and this effect was replicated by exogenous PGE2 treatment of parental tumor cells. In contrast to previous studies in other cell types, in nonsmall cell lung cancer cells survivin was expressed in a cell cycle-independent manner. When established in SCID mice in vivo, COX-2 antisense-derived tumors had significantly decreased survivin levels while COX-2 sense-derived tumors demonstrated elevated levels compared with controls. In accord with these findings, survivin and COX-2 were frequently upregulated and co-expressed in human lung cancers in situ.

Inhibitors of cyclo-oxygenase 2: a new class of anticancer agents?

Experimental studies have shown that cyclo-oxygenase 2 (COX2) is involved in tumour development and progression. Selective inhibitors of COX2 (coxibs) block tumour growth through many mechanisms, especially by antiangiogenic and proapoptotic effects. In experimental models, coxibs potentiate the activity of cytotoxic agents, hormones, and radiotherapy. Large clinical studies have shown chemopreventive activity of coxibs in colorectal cancer. The findings of preclinical studies coupled with the overexpression of COX2 observed in advanced human tumours are the basis for new therapeutic anticancer strategies based on combinations of coxibs with other anticancer treatment modalities. Early clinical studies have documented the feasibility, good tolerability, and promising activity of coxibs combined with chemotherapy in patients with advanced colorectal and non-small-cell lung cancers. Here, we describe the recent findings on the antitumour effects of coxibs with particular focus on the opportunities that have emerged for treatment of cancer.

Cyclo-oxygenase inhibition in colorectal adenomas and cancer

Increasing evidence indicates that Non-steroidal anti-inflammatory drugs (NSAIDs), compounds that inhibit the enzymatic activity of cyclooxygenase (COX), can reduce the number and size of adenomas in patients with familial adenomatous polyposis as well as the incidence of colorectal cancer. The COX enzyme family consists of the classic COX-1 and a second enzyme, COX-2, which is induced by various stimuli, such as mitogens and cytokines. While it is well proven that COX-2 overexpression is a central event in colorectal carcinogenesis, that prostaglandins (PGs) can contribute to tumorigenesis, and that COX-2 selective inhibitors are active chemopreventive agents, the molecular mechanisms by which NSAIDs exert their chemopreventive effect is not fully understood. However, significant advances have been made in understanding the interference of NSAIDs with the pathways that control cell growth and survival even independently from their COX-inhibiting properties, making their use attractive both alone and in combination with standard therapies in the treatment of advanced colorectal cancer. In addition, the recently recognized anti-angiogenic and radiosensitizer properties of COX-2 inhibitors support, further suggest their use in the adjuvant setting.

Complex and controversial issues in locally advanced non-small cell lung carcinoma

Locally advanced non-small cell lung carcinoma (NSCLC) presents enormous challenges to clinicians and researchers. Because of the absence of metastatic disease, it is a potentially curable condition, greatly differentiating it from stage IV NSCLC. The median and actuarial survival rates are poor, though clearly improved in the past decade, and clearly better than several other types of locally advanced malignancies (e.g., pancreatic cancer, glioblastoma). As demonstrated in Table I, the combination of chemotherapy and radiotherapy has earned the designation of "standard of care" for most good-performance-status patients with locally advanced NSCLC. It is likely that improvements in radiotherapy have also contributed to the enhanced survival and local control rates in this disease. With concurrent chemoradiotherapy, the majority of patients can receive a substantial local response (Fig. 1). Many achieve durable local control, only to succumb to eventual distant metastatic failure. There remains much room for improvement, and there are several avenues for clinical and translational research that offer promise. These include new systemic chemotherapy options (and newer ways of combining these drugs with radiotherapy), improvements in radiotherapy fractionation and dose intensity, methods of protection from chemoradiotherapy toxicity, specific therapies to prevent brain metastatic failure, and the integration of biologically targeted molecules into chemoradiation programs. This article summarizes the advances in the treatment of locally advanced NSCLC over the past several decades and explores some of the many remaining controversies and areas for future investigation.

Carcinogenesis and cyclooxygenase: the potential role of COX-2 inhibition in upper aerodigestive tract cancer

Cyclooxygenase-2 (COX-2) is upregulated in a number of epithelial cancers, including in upper aerodigestive tract (UADT) premalignant and malignant lesions. The purpose of this review is to provide a comprehensive examination of the potential of COX-2 inhibition in prevention of UADT premalignant and malignant disease. A Medline and Cancerlit literature search was conducted for the period 1993-2002, and identified literature was reviewed. There is evidence from in vitro studies, as well as animal models, that inhibition of COX-2 may suppress carcinogenesis by affecting a number of pathways of carcinogenesis, promoting apoptosis and inhibiting angiogenesis. Preliminary studies of gastro-intestinal (GI) carcinogenesis suggest that COX-2 inhibitors may represent an approach to the chemoprevention of epithelial cancers. COX-2 inhibitors may have a potential role in chemoprevention of UADT cancer, and clinical trials appear warranted.

Cyclo-oxygenase 2 inhibition in colorectal cancer therapy

BACKGROUND

Cyclo-oxygenase inhibition for the treatment of colorectal neoplasia has been studied with renewed interest since the discovery of cyclo-oxygenase (Cox) 2 and the introduction of specific Cox-2 inhibitors. These drugs have implications for both the prevention of colorectal carcinoma and the potential treatment of the disease.

METHODS AND RESULTS

A Medline database search was performed for articles using the keywords "colonic, colon or rectal and neoplasia or cancer" and "cyclo-oxygenase or Cox-2." Cross-references of relevant historical papers were also included. There is substantial evidence that Cox-2 plays a role in the development and progression of colorectal cancer. The specific inhibition of this enzyme has been shown to inhibit cancer growth in in vitro and in vivo models. The mechanisms of action for these effects are poorly understood and potential clinical applications at present remain under investigation.

CONCLUSION

Cox-2 inhibitors have great promise as useful additions to current cancer treatments. There is a need for randomized clinical trials to define a role for these drugs in chemoprevention, recurrence prophylaxis, and adjuvant therapy for colorectal and other solid tumours.

Combination of a COX-2 inhibitor with radiotherapy or radiochemotherapy in the treatment of thoracic cancer

Cyclooxygenase-2 (COX-2) is an enzyme involved in prostaglandin production in pathologic states such as inflammatory processes and cancer. The enzyme is often overexpressed in premalignant lesions and cancer, including cancers of the lung and esophagus. Inhibition of this enzyme with selective COX-2 inhibitors was found to enhance tumor response to radiation in preclinical studies, suggesting that these agents can improve the response of various cancers to radiotherapy. On the basis of these preclinical findings, clinical trials of the combination of celecoxib, a selective COX-2 inhibitor, with radiotherapy were initiated in patients with lung carcinoma and with chemoradiotherapy in patients with esophageal carcinoma. The rationale for using selective COX-2 inhibitors is discussed, and the current clinical protocols and the initial findings are described.

COX-2 inhibitors as radiosensitizing agents for cancer therapy

Prostaglandins have long been known to impact the radiosensitivity of cells and tissues, and many studies have centered on exploiting nonspecific prostaglandin inhibitors such as NSAIDs for therapeutic gain. These studies have ultimately been unsuccessful due to the lack of targeted specificity against the tumor. The discovery of the inducible cyclooxygenase enzyme (COX-2) and development of some highly selective inhibitors (which spare the constitutive COX-1 activity) has renewed excitement for modulating tumor prostaglandins as a method of specific radiosensitization of tumors, while sparing normal tissues. This review discusses these new data and generates a rationale for use of COX-2 inhibitors as radiosensitizing agents in cancer therapy.

Targeted therapies for stage III non-small cell lung cancer: integration in the combined modality setting

Combined modality therapy represents current standard therapy for locoregionally advanced non-small cell lung cancer. In particular, concomitant chemoradiotherapy has emerged as the preferred approach. At the same time, efforts to increase locoregional and systemic antitumor activity are necessary to further improve long-term survival rates for these patients. In recent years, multiple cellular targets have emerged in the development of novel antitumor therapies. Several of these are of high relevance in the carcinogenesis of lung cancer including the epidermal growth factor receptor (EGFR), the ras signaling pathway, tumor angiogenesis, and cyclooxygenase-2 (COX-2) expression. Novel agents directed against these targets are currently under development with promising early results in non-small cell lung cancer when administered as single agents or in combination with chemotherapy in stage IV or recurrent disease. Similarly their use with concurrent radiation therapy is supported by preclinical models. Selected early clinical trials utilizing these agents in combination with radiotherapy or chemoradiotherapy are discussed.

Cyclooxygenase-2 (COX-2) expression in human meningioma as a function of tumor grade

Meningiomas are one of the most frequent central nervous system tumors, with an annual incidence in the United States of approximately 2.5 per 100,000 people. An intense interest exists in evaluating new molecular markers that may serve as potential therapeutic targets. Cyclooxygenase-2 (COX-2) is upregulated in a number of epithelial tumors, but to date, there are no published reports about the expression of COX-2 in meningioma. This study evaluated a possible relationship between COX-2 expression and malignant progression of meningioma. Eighty-three specimens of meningioma from the surgical pathology database of Thomas Jefferson University Hospital were evaluated. The hematoxylin and eosin (H&E)-stained slides were reviewed, and representative paraffin-embedded tissue sections containing the index cases were chosen and immunohistochemically stained for COX-2 expression. The H&E-stained sections of the individual tumors were classified according to the 1993 and 2000 World Health Organization (WHO) criteria for grading of meningiomas. The COX-2-stained slides were then reviewed and an immunohistochemical score was calculated and analyzed for statistical significance. The association between tumor grade and COX-2 expression is highly significant using the WHO-1993 grading criteria, (p = 0.012). Tumors with a more aggressive phenotype (benign --> atypical --> malignant) are associated with increasingly higher levels of COX-2. Using the 2000 WHO classification system, however, the association between tumor classification and COX-2 expression was not significant (p = 0.17), although the overwhelming percentage of tumors expressed COX-2. The association of COX-2 and meningioma is unique and represents a potential area for therapeutic intervention with selective COX-2 inhibitors, either as adjunct or in combination with radiation therapy.

Initial experience combining cyclooxygenase-2 inhibition with chemoradiation for locally advanced pancreatic cancer

Pancreatic cancer is a lethal disease that is resistant to chemotherapy and radiotherapy. Gemcitabine has recently been shown to be an improvement over 5-fluorouracil in patients with advanced disease. It is also a potent radiosensitizer, which has led to the investigation of gemcitabine with concurrent radiotherapy. However, preliminary results indicate that there are significant limitations to this approach in this challenging disease. Pancreatic cancer cells have alterations in many molecular signaling pathways that may be responsible for their resistance to cytotoxic therapy and aggressive behavior. Cyclooxygenase-2 (COX-2) is commonly overexpressed in pancreatic tumors, and preclinical evidence indicates that selective COX-2 inhibition enhances both chemotherapy and radiotherapy response, without affecting normal tissue damage. We have initiated preclinical studies as well as a phase I clinical protocol evaluating the combination of gemcitabine and celecoxib (Celebrex) with radiotherapy. In preclinical studies, celecelecoxib strongly enhanced the antitumor efficacy of chemoradiation. However, preliminary observations from both the preclinical experiments as well as the clinical protocol have revealed more toxicity with this combination than with gemcitabine and radiotherapy alone. These observations require further study, but are cause for concern when combining gemcitabine, radiotherapy, and celecoxib.

COX-2 inhibitors as radiation sensitizers for upper GI tract cancers: esophagus, stomach, and pancreas

Cancers of the esophagus, stomach, and pancreas have been successfully treated recently with combinations of radiosensitizing chemotherapy and irradiation. New approaches building onto 5-fluorouracil chemoradiation include capecitabine (Xeloda) and irradiation. Capecitabine is an oral 5-fluorouracil (5-FU) prodrug that is more convenient than using infusional 5-FU, appears to have a similar therapeutic profile, and can be combined with daily irradiation. The addition of a cyclooxygenase-2 (COX-2) inhibitor is being investigated in upper gastrointestinal cancer sites because there is a high degree of overexpression of COX-2 in these cancers.

Advances in combined radiation therapy for the management of rectal cancer

Significant advances have been made in the use of adjuvant radiation for patients with localized rectal cancer. Recent progress in adjuvant postoperative radiation regimens relates to the integration of systemic therapy into radiation, as well as redefining the techniques and sequences for both modalities. The adjuvant radiation management approach in both North America and Europe has been shifting towards preoperative adjuvant therapy to promote sphincter-preserving surgery and to decrease acute and late toxicity. Although 5-fluorouracil-based chemotherapy in combination with radiation remains the standard adjuvant therapy for rectal cancer, the integration of novel chemotherapeutic agents and biologic modulators remains an active area of investigation.

Cyclooxygenase-2 (COX-2) and epidermal growth factor receptor (EGFR) expression in human pituitary macroadenomas

Macroadenomas are tumors of the pituitary gland and are considered almost to be always benign and curable. The clinical manifestations of a pituitary tumor depend on the hormone secreted by the tumor as well as on the pattern of tumor growth within the sella turcica. Current trends attempt to target new molecular markers that also may serve as potential therapeutic targets. Cyclooxygenase-2 (COX-2) and epidermal growth factor receptor (EGFR) are upregulated in a number of epithelial tumors. No published reports exist about expression of COX-2 in pituitary macroadenomas, and only a few reports with differing results exist concerning EGFR expression in pituitary macroadenomas. This study sought to determine whether a relationship exists between COX-2 and EGFR expression and pituitary macroadenomas. Thirty specimens of pituitary macroadenomas were evaluated after being identified in the surgical pathology database of Thomas Jefferson University Hospital. The hematoxylin and eosin-stained slides were reviewed, and the representative paraffin blocks containing the index case were chosen and immunohistochemically stained for COX-2 and EGFR expression. The COX-2 and EGFR-stained slides were reviewed and an immunohistochemical score was calculated and analyzed. The pituitary macroadenomas were classified on the basis of hormone expression: none (nonsecreting), minor (nondominant, plurihormonal), single (dominant nonplurihormonal), or plurihormonal (dominant plurihormonal). The hormonal classification was then analyzed for association with COX-2 expression. COX-2 expression was significantly associated with plurihormonal pituitary macroadenomas (p value 0.03). COX-2 expression was significantly associated with expression of luteinizing hormone (p value 0.007) and with expression of thyroid-stimulating hormone (TSH) (p value 0.04). Additionally, COX-2 expression was significantly associated with single-hormone of pituitary adenoma (p value 0.049). The expression of COX-2 in 100% of the normal autopsy pituitary glands establishes an additional central nervous system location of COX-2 expression. EGFR was not expressed in any of the pituitary macroadenomas. The expression of COX-2 in plurihormonal pituitary macroadenomas, particularly those secreting TSH, may be a potential target for treatment in addition to surgical and/or radiotherapy treatment in these benign but clinically significant tumors. COX-2 is expressed in normal autopsy pituitary tissue.

Cyclooxygenase-2 (COX-2) enzyme inhibitors and radiotherapy: preclinical basis

Cyclooxygenase-2 (COX-2), an enzyme induced by proinflammatory cytokines, mitogenic substances, oncogenes, growth factors, and hypoxia, among others, is involved in the metabolic conversion of arachidonic acid to prostaglandins in inflamed tissues and neoplasia. COX-2 is often overexpressed in malignant tumors and premalignant lesions and is linked to carcinogenesis, maintenance of progressive tumor growth, and facilitation of metastatic spread. Because COX-2 may also be a determinant of tumor radioresistance, its inhibition or inhibition of its products (prostaglandins) may improve tumor response to radiotherapy. Preclinical studies have shown that treatment with selective COX-2 inhibitors significantly enhances tumor response to radiation without appreciably affecting normal tissue radioresponse. The underlying mechanisms of the COX-2 inhibitor-radiation interactions seem to be multiple, with the enzyme inhibitor directly or indirectly augmenting tumor cell destruction by radiation. Thus, use of selective COX-2 inhibitors is a potential approach for improving cancer radiotherapy.

COX-2 inhibitor as a radiation enhancer: new strategies for the treatment of lung cancer

Lung cancer is one of the most common causes of cancer-related mortality throughout the world, and the incidence continues to increase. Smoking is the number one cause of lung cancer. Emerging data have implicated cyclooxygenase-2 (COX-2) and prostanoid production in the pathogenesis of lung carcinoma. In invasive lung tumors, COX-2 upregulation has been reported in up to 90% of cases. COX-2 upregulation is an early event in the development of non-small-cell lung cancer and may be integral to the development of new blood vessels and production of specific proteases that are critical to growth and spread of lung malignancies. COX-2 inhibitors are known to enhance the chemosensitivity in COX-2 overexpressing lung cancer cell lines. Recently, we have demonstrated that selective COX-2 inhibitors also enhance the effect of radiation in COX-2 overexpressed cells. Therefore, inhibitors of COX-2 in combination with chemoradiation therapy may be an alternative strategy that can be tested in clinical trials. The combination of COX-2 inhibitors and radiation suggest a complementary strategy to target angiogenesis while potentially minimizing the impact on quality of life. Currently, several groups are conducting clinical trials in cervix cancer, lung cancer, and brain tumors, using inhibitors of COX-2 in combination with chemotherapy and radiation therapy. These clinical trials will help to elucidate the role of this interesting class.

The importance of the eicosanoid pathway in lung cancer

Non-steroidal anti-inflammatory agents (NSAIDs) inhibit the conversion of arachadonic acid to a class of inflammatory mediators known as eicosanoids. These minimally toxic drugs have demonstrated important anti-cancer properties in colorectal cancer and pre-clinical models have shown their potential for use in the treatment of non-small cell lung cancer (NSCLC). Clinical trials are underway investigating the efficacy of eicosanoid inhibitors alone and in combination with radiation and chemotherapy.

Epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) negatively affect overall survival in carcinoma of the cervix treated with radiotherapy

PURPOSE

The purpose of this study was to examine a variety of biomarkers in carcinoma of the cervix to better characterize (1). the natural history of the disease, (2). response to radiotherapy (RT), and (3). potential for new therapeutic strategies.

MATERIALS AND METHODS

Fifty-five patients with Stage IB-IVA carcinoma of the cervix, treated with definitive intent RT, and on whom tumor tissue blocks were available were included in this study. Charts were reviewed for clinical parameters and disease status. Immunohistochemistry was performed for epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), CD34, topoisomerase II alpha (topo-II), and cyclooxygenase-2 (COX-2). Univariate and multivariate Cox proportional hazards modeling was performed with disease-free survival (DFS) and overall survival (OS) as the end points. Biomarkers were evaluated for correlation between various prognostic factors.

RESULTS

In this series of 55 patients with carcinoma of the cervix treated with definitive RT, only stage was significant on univariate analysis for DFS (p < 0.0001). On univariate analysis, increasing FIGO stage (p < 0.0001) and membranous staining of EGFR (p < 0.037) indicated diminished OS. On multivariate analysis for DFS, COX-2, VEGF, and stage were significant (p = 0.012, p = 0.014, and p = 0.03, respectively), with increased expression indicating a worse prognosis. For OS, multivariate analysis revealed that VEGF, EGFR, and FIGO stage were significant (p = 0.005, p = 0.011, and p < 0.0001, respectively). Significant direct correlations were identified between VEGF and CD34 (p = 0.04), COX-2 and topo-II (p = 0.04), COX-2 and grade (p = 0.04), and tumor size and clinical stage (p = 0.04).

CONCLUSION

Multivariate analysis revealed that increased staining for VEGF and COX-2 indicated diminished DFS, and VEGF and EGFR identified patients at increased risk of death. A significant direct correlation between VEGF and CD34 implicates the process of angiogenesis. Topo-II is a proliferative marker and it correlated directly with COX-2, indicating that expression of COX-2 may be greater in more proliferative tumors. Increased expression of EGFR, VEGF, and COX-2 has identified patients with a worse prognosis in cancer of the cervix. These data support the investigation of therapeutics that target these proteins in carcinoma of the cervix.

Celecoxib, a selective cyclo-oxygenase-2 inhibitor, enhances the response to preoperative paclitaxel and carboplatin in early-stage non-small-cell lung cancer

PURPOSE

Preclinical studies suggest that treatment with a selective cyclo-oxygenase-2 (COX-2) inhibitor may augment the antitumor effects of chemotherapy. In this study, patients with non-small-cell lung cancer (NSCLC) were preoperatively treated with celecoxib in combination with chemotherapy. End points were toxicity, response rates, and measurement of intratumoral levels of prostaglandin E2 (PGE2).

METHODS

In this phase II trial, 29 patients with stages IB to IIIA NSCLC were treated with two preoperative cycles of paclitaxel and carboplatin, as well as daily celecoxib, followed by surgical resection. Levels of PGE2 in the primary tumors and adjacent normal lung tissue were compared in 17 study patients versus 13 controls, who received preoperative paclitaxel/carboplatin without celecoxib.

RESULTS

All patients completed preoperative chemotherapy, and 26 completed preoperative celecoxib. The overall clinical response rate was 65% (48% with partial response; 17% with complete response). Grade 3 or 4 neutropenia was observed in 18 patients (62%). Twenty-eight patients were explored and underwent complete resection of their tumors. There were no complete pathologic responses, but seven patients (24%) had minimal residual microscopic disease. The addition of celecoxib to a regimen of paclitaxel and carboplatin abrogated the marked increase in levels of PGE2 detected in primary tumors after treatment with paclitaxel and carboplatin alone.

CONCLUSION

In comparison with historically reported response rates, these data suggest that the addition of a selective COX-2 inhibitor may enhance the response to preoperative paclitaxel and carboplatin in patients with NSCLC. Moreover, treatment with celecoxib 400 mg twice daily was sufficient to normalize the increase in PGE2 levels found in NSCLC patients after treatment with paclitaxel and carboplatin. Confirmatory trials are planned.

Combined-modality treatment of solid tumors using radiotherapy and molecular targeted agents

PURPOSE

Molecular targeted agents have been combined with radiotherapy (RT) in recent clinical trials in an effort to optimize the therapeutic index of RT. The appeal of this strategy lies in their potential target specificity and clinically acceptable toxicity.

DESIGN

This article integrates the salient, published research findings into the underlying molecular mechanisms, preclinical efficacy, and clinical applicability of combining RT with molecular targeted agents. These agents include inhibitors of intracellular signal transduction molecules, modulators of apoptosis, inhibitors of cell cycle checkpoints control, antiangiogenic agents, and cyclo-oxygenase-2 inhibitors.

RESULTS

Molecular targeted agents can have direct effects on the cytoprotective and cytotoxic pathways implicated in the cellular response to ionizing radiation (IR). These pathways involve cellular proliferation, DNA repair, cell cycle progression, nuclear transcription, tumor angiogenesis, and prostanoid-associated inflammation. These pathways can also converge to alter RT-induced apoptosis, terminal growth arrest, and reproductive cell death. Pharmacologic modulation of these pathways may potentially enhance tumor response to RT though inhibition of tumor repopulation, improvement of tumor oxygenation, redistribution during the cell cycle, and alteration of intrinsic tumor radiosensitivity.

CONCLUSION

Combining RT and molecular targeted agents is a rational approach in the treatment of solid tumors. Translation of this approach from promising preclinical data to clinical trials is actively underway.

Concurrent chemoradiotherapy for inoperable stage III non-small-cell lung cancer

Chemoradiotherapy has become the standard treatment for patients with locally advanced non-small-cell lung cancer on the basis of several large randomized trials. Despite an increase in median survival from 10 months with radiotherapy alone to 16 to 17 months with concurrent chemoradiotherapy, long-term survival in this disease remains modest at best. With the advent of new biologic agents targeting specific cellular pathways associated with malignant progression, combined-modality therapy has the potential to target tumors selectively with less toxicity.

The Potential Contributions of Chronic Inflammation to Lung Carcinogenesis

A number of lines of evidence suggests that chronic inflammation contributes to the process of carcinogenesis. In this article, this theme is explored with particular emphasis on the involvement of inflammation in the development of lung cancer. A number of molecular pathways activated in chronic inflammation may contribute to lung carcinogenesis. The challenge is to conceptualize a cohesive picture of this complex biology that allows for effective pharmaceutical intervention. Initial therapeutic efforts involve strategies to block single pathways, such as with cyclooxygenase (COX) activity. However, the more that is learned about the consequences of COX activity, the more evident are the relationships of this enzyme to other classes of regulatory molecules such as the potent nuclear factor-kB. In light of this emerging picture, more global intervention strategies, such as with drug combinations, may be essential for success. Further basic study is essential to sort out possible molecular relationships and to permit elucidation of the most critical regulatory circuits. Given the complexity of these molecular interactions, well-designed clinical trials that specifically evaluate the precise effects of particular antiinflammatory drugs on lung carcinogenesis will also be critical to sort out the complexity and to validate successful approaches to arresting lung carcinogenesis.

Role of Cyclooxygenase-2 Inhibitors in Combination with Radiation Therapy in Lung Cancer

Cyclooxygenase-2 (COX-2) is an enzyme involved in prostaglandin production in pathologic states such as inflammatory disorders and cancer. The enzyme is often overexpressed in premalignant lesions and cancer of the lung. Overexpression of COX-2 in lung cancer is associated with more aggressive biological tumor behavior and adverse patient outcome. In preclinical studies, inhibition of this enzyme with selective COX-2 inhibitors enhances tumor response to radiation and chemotherapeutic agents. These findings have been rapidly advanced to clinical oncology. Clinical trials of the combination of selective COX-2 inhibitors with radiation therapy, chemotherapy, or both in patients with lung cancer have been initiated and some preliminary results are available. In this review, we describe the relationship between overexpression of COX-2 and lung cancer, the antitumor effect of selective COX-2 inhibitors, discuss the rationale for using selective COX-2 inhibitors combined with radiation therapy and chemotherapy, and summarize current clinical protocols and initial findings.

Tumor-host interactions accompanying the growth of the G:5:113 fibrosarcoma in the mouse: possibilities for a new therapeutic approach?

The experiments were aimed at describing in detail some interactions between a solid tumor growing from subcutaneously transplanted G:5:113 fibrosarcoma cells in vivo and its mouse host. The tumor was found to elevate significantly the number of granulocytes in the peripheral blood of the host after having achieved the volume of about 1 cm3 (day 40 after transplantation). Blood plasma from fibrosarcoma-bearing mice stimulated proliferation of progenitor cells for granulocytes and macrophages (GM-CFC) in vitro and suppressed growth of G:5:113 cell population in culture. Interestingly, both effects were observable as early as week 1 when the tumor was still macroscopically invisible and unpalpable. Conditioned medium from cultures of G:5:113 fibrosarcoma cells stimulated proliferation of GM-CFC in vitro. These findings might represent a starting point for studies aimed at designing new therapeutic approaches for the treatment of fibrosarcoma.

High cyclooxygenase-2 expression in cervical adenocarcinomas

OBJECTIVE

The purpose of this study was to examine the relationships between cyclooxygenase-2 (COX-2) expression and prognostic factors in cervical carcinomas.

METHODS

We studied COX-2 expression in 53 women with cervical cancers, including 35 squamous cell carcinomas (SCCs), 1 adenosquamous cell carcinoma (ASCC), and 17 adenocarcinomas (ACs), using commercially available polyclonal antibodies on Formalin-fixed, paraffin-embedded tissues. Normal cervical tissues were obtained as from other patients with uterine myomas treated with a total hysterectomy (n = 16). The immunoreactivity was quantified using an immunohistochemical scoring system that approximates the use of an image analysis-based system.

RESULTS

Twenty-two cervical cancer tissues (41.5%), including 10 SCCs and 12 ACs, expressed COX-2 at a moderate to strong level, which significantly, differed from the negligible expression found in the control group of 16 normal cervical tissues (P = 0.001). Different cell types showed significantly different expression levels of COX-2 (SCC at 28.6% vs AC at 70.6%, P = 0.004). The presence of deep stromal invasion (n = 40) showed a significant inverse relationship to COX-2 expression (32.5% vs 69.2%, P = 0.02). The expression of COX-2 in well-differentiated carcinomas was significantly increased compared to that in moderately and poorly differentiated carcinomas (72.7% vs 33.3%, respectively, P = 0.018).

CONCLUSIONS

Overexpression of COX-2 was found in both SCC and AC, but SCCs showed infrequent and low expression. These findings suggest that increased COX-2 expression may play an important role in cervical adenocarcinomas.

Cyclooxygenase 2: a molecular target for cancer prevention and treatment

Cyclooxygenase2 (COX-2), an inducible prostaglandin G/H synthase, is overexpressed in several human cancers. Here, the potential utility of selective COX-2 inhibitors in the prevention and treatment of cancer is considered. The mechanisms by which COX-2 levels increase in cancers, key data that indicate a causal link between increased COX-2 activity and tumorigenesis, and possible mechanisms of action of COX-2 are discussed. In a proof-of-principle clinical trial, treatment with the selective COX-2 inhibitor celecoxib reduced the number of colorectal polyps in patients with familial adenomatous polyposis. Selective COX-2 inhibitors appear to be sufficiently safe to permit large-scale clinical testing and numerous clinical trials are currently under way to determine whether selective inhibitors of COX-2 are effective in the prevention and treatment of cancer.

Chemoradiotherapy: emerging treatment improvement strategies

BACKGROUND

The use of chemotherapeutic drugs in combination with radiotherapy has become a common strategy for the treatment of advanced cancer. Solid evidence exists showing that chemotherapy administered during the course of radiotherapy (concurrent chemoradiotherapy) increases both local tumor control and patient survival in a number of cancer sites, including head and neck cancer. These therapy improvements, however, have been achieved at the expense of considerable toxicity, which underscores the need for further improvements.

METHODS

The current status of chemoradiotherapy clinical trials for head and neck cancer and research on the emerging treatment improvements were reviewed. A review of potential treatment improvement strategies focused on preclinical investigations on newer chemotherapeutic agents, notably taxanes and nucleoside analogues, as well as on molecular targets such as epidermal growth factor receptor (EGFR) or cyclooxygenase-2 (COX-2) enzyme.

RESULTS

Concurrent, but not induction (drugs given before radiotherapy), chemoradiotherapy improves locoregional tumor control and survival benefit in head and neck carcinoma relative to radiotherapy alone. In comparison, both concurrent and induction chemoradiotherapy showed therapeutic advantage over radiotherapy alone in the treatment of lung cancer. These therapeutic improvements were achieved with standard chemotherapeutic drugs, most commonly cisplatin-based chemotherapy. Biologically, chemotherapy interacts with radiation through a number of mechanisms, including inhibition of cellular repair, cell cycle effects, and inhibition of tumor cell regeneration. Potential avenues emerged to further improve chemoradiotherapy. One of these involves the newer chemotherapeutic agents, taxanes and nucleoside analogues, which in preclinical studies exhibited strong tumor radiosensitization and therapeutic gain. The clinical benefit of these agents is currently under testing. Another approach for improvement of chemoradiotherapy consists of inhibiting molecules selectively or preferentially expressed on tumor cells, such as EGFR and COX-2, both shown to render cellular resistance to drugs or radiation. Agents that selectively inhibit these molecules are becoming available at a rapid rate, and many of them have been shown in preclinical testing to be highly effective in improving tumor radioresponse or chemoresponse without affecting normal tissues.

CONCLUSIONS

Concurrent chemoradiotherapy, using standard chemotherapeutic agents, has emerged as an effective treatment for advanced cancer, but unfortunately at the expense of considerable increase in normal tissue toxicity. There are a number of potential emerging treatment strategies to further improve chemoradiotherapy. One consists of using newer chemotherapeutic drugs, which in preclinical studies are potent enhancers of tumor radioresponse. Another approach consists of targeting EGFR or COX-2 with selective inhibitors of these molecules.

Non steroidal anti-inflammatory drugs and COX-2 inhibitors as anti-cancer therapeutics: hypes, hopes and reality

Non-steroidal anti-inflammatory drugs (NSAIDs) and specific inhibitors of cyclooxygenase (COX)-2, are therapeutic groups widely used for the treatment of pain, inflammation and fever. There is growing experimental and clinical evidence indicating NSAIDs and COX-2 inhibitors also have anti-cancer activity. Epidemiological studies have shown that regular use of Aspirin and other NSAIDs reduces the risk of developing cancer, in particular of the colon. Molecular pathology studies have revealed that COX-2 is expressed by cancer cells and cells of the tumor stroma during tumor progression and in response to chemotherapy or radiotherapy. Experimental studies have demonstrated that COX-2 over expression promotes tumorigenesis, and that NSAIDs and COX-2 inhibitors suppress tumorigenesis and tumor progression. Clinical trials have shown that NSAIDs and COX-2 inhibitors suppress colon polyp formation and malignant progression in patients with familial adenomatous polyposis (FAP) syndrome. Recent advances in the understanding of the cellular and molecular mechanisms of the anti-cancer effects of NSAIDs and COX-2 inhibitors have demonstrated that these drugs target both tumor cells and the tumor vasculature. The therapeutic benefits of COX-2 inhibitors in the treatment of human cancer in combination with chemotherapy or radiotherapy are currently being tested in clinical trials. In this article we will review recent advances in the understanding of the anti-tumor mechanisms of these drugs and discuss their potential application in clinical oncology.

Selective cyclooxygenase-2 inhibition: a target in cancer prevention and treatment

A major goal in the area of cancer prevention and treatment is to make rational use of defined molecular targets in order to block carcinogenesis. Studies conducted in experimental animal models for many human cancers, including those of lung, skin, mammary gland, urinary bladder, colon, and pancreas, have demonstrated that carcinogenesis often may be inhibited by the administration of a highly diverse group of biologic and chemical agents. One very promising and well-studied target is cyclooxygenase (COX)-2. Interestingly, a number of cancers appear to overexpress the COX-2 enzyme, which may play several roles in carcinogenesis. Recent clinical studies have demonstrated the effect of COX-2 inhibitors in the treatment of familial adenomatous polyposis, a genetic disorder that increases the risk for developing colorectal cancer. Ongoing clinical trials with COX-2 inhibitors will increase our understanding and may give us profound insights into the general applicability of this new targeted approach for cancer control.

In vitro enhancement of tumor cell radiosensitivity by a selective inhibitor of cyclooxygenase-2 enzyme: mechanistic considerations

PURPOSE

Selective cyclooxygenase-2 inhibitors have been reported to enhance the tumor response to radiation in vivo, but the cellular mechanisms underlying the radiosensitizing effect are not understood. In the present study, we investigated several possible mechanisms using a murine sarcoma cell culture system.

METHODS AND MATERIALS

Cells derived from a murine sarcoma, designated NFSA, were cultured in vitro and exposed to different (either single or split) doses of radiation with and without a pretreatment of SC-236 (4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1H-pyrazol-l-yl] benzene sulfonamide), a selective cyclooxygenase-2 (COX-2) inhibitor. The cells were assayed for clonogenic survival to determine the radiosensitizing effect of SC-236. In addition, MTT assay and TUNEL assay were performed to determine the effects of SC-236 and radiation on the cell survival and cell cycle distribution. RNase protection assay was performed on the total RNA extract using probes that encoded for selected cell cycle regulatory proteins, such as cyclins and cyclin-dependent kinases. To monitor the extent of COX-2 activity and its role in radiosensitization, the cellular content of prostaglandin E2, a major metabolite of COX-2 activity on arachidonic acid, was also determined.

RESULTS

The cell clonogenic survival assay showed that SC-236 significantly enhanced tumor cell radiosensitivity: 50 microM SC-236 increased it by a factor of 1.51 at the 0.1 cell survival level. Treatment with SC-236 (50 microM, 3 days) removed the "shoulder" region on the radiation survival curve, suggesting that the drug inhibited repair of sublethal radiation damage. The inhibition was confirmed by split-dose experiments where two doses (3 Gy each) of radiation were given 4 h apart. The cells exposed to radiation only repaired the damage by a factor of 1.44, whereas those treated with SC-236 plus radiation repaired it by a factor of 1.1 only. Whereas SC-236 induced apoptosis in these NFSA cells, radiation did not. No further increase in apoptosis was observed when the cells were exposed to both SC-236 and radiation, suggesting that SC-236 did not render tumor cells more susceptible to radiation-induced apoptosis. The RNase protection assay showed that SC-236 (50 microM, 3 days) inhibited the expression of cyclins A and B, as well as cyclin-dependent kinase-1. Inhibition of these cell cycle regulatory elements by SC-236 was associated with the arrest of cells in the radiosensitive G2-M phase (67%), determined by flow cytometry.

CONCLUSIONS

SC-236 significantly enhanced radiosensitivity of tumor cells; the magnitude of sensitivity was dependent on the drug's concentration. The likely mechanisms involve accumulation of cells in the radiosensitive G2-M phase of the cell cycle and inhibition of repair from sublethal radiation damage.

Irinotecan in Non–Small-Cell Lung Cancer: Status of Ongoing Trials

Irinotecan possesses significant single-agent activity in non-small-cell lung cancer (NSCLC) and is active in combination with either cisplatin or carboplatin. Two phase III trials completed in Japan have suggested that the combination of irinotecan/cisplatin yields superior survival rates in stage IV NSCLC patients compared to vindesine/cisplatin. The principal toxicities of the irinotecan/cisplatin regimen are neutropenia and diarrhea. This regimen is currently being tested in Japan against regimens commonly used in the United States, such as cisplatin/gemcitabine, cisplatin/vinorelbine, and carboplatin/paclitaxel. These studies include evaluation of monthly as well as weekly schedules of cisplatin in combination with irinotecan as well as a triplet regimen of irinotecan/carboplatin/paclitaxel. Ongoing trials are evaluating these regimens as well as irinotecan/carboplatin and several nonplatinum-based irinotecan-containing doublets in both the first- and second-line treatment of advanced NSCLC. Several ongoing trials are attempting to integrate irinotecan with thoracic radiation therapy in stage III NSCLC. These trials are using irinotecan-containing regimens as induction and concurrent therapy with thoracic radiation therapy. Irinotecan is also being evaluated in the preoperative setting in early-stage resectable NSCLC. Many of these trials are also incorporating celecoxib, a potent inhibitor of the cyclooxygenase-2 pathway, in combination with irinotecan-containing regimens in both advanced as well as early-stage NSCLC. Future trials should focus on the integration of the new targeted agents in combination with irinotecan-containing regimens in all stages of NSCLC.

Phase III study of ibuprofen versus placebo for radiation-induced genitourinary side effects

PURPOSE

On the basis of our anecdotal clinical observations that nonsteroidal anti-inflammatory agents relieved dysuria during radiotherapy for patients with prostate cancer, we conducted a Phase III randomized trial of ibuprofen vs. placebo for patients who had an increase in acute urinary symptoms. Our in vitro and in vivo laboratory data with a higher concentration of ibuprofen than achievable in this study demonstrated radiosensitization. This study examined whether the inflammatory response within the prostate during radiotherapy would respond to the standard dose of ibuprofen as assessed by a symptom score.

METHODS AND MATERIALS

Patients were registered to the study and were followed weekly with a formal symptom assessment. A double-blind randomization to ibuprofen, 400 mg q.i.d., vs. placebo for 7 days was done at a time when the severity score increased. The symptom response was evaluated at the end of the week.

RESULTS

Between 1995 and 1998, 100 patients were entered, 28 did not have a sufficient change in symptom score to be randomized, and 19 were either unable to take ibuprofen or withdrew before randomization. Of the 53 patients randomized, 27 received placebo and 26 ibuprofen. No statistically significant differences were found between the placebo and ibuprofen groups between baseline and randomization or between randomization and the 1-week posttreatment assessment. Neither group had a change in symptom severity between randomization and the 1-week posttreatment evaluation.

CONCLUSION

The standard anti-inflammatory dose of ibuprofen did not relieve the acute urinary or rectal symptoms during radiotherapy for prostate cancer. The nonsteroidal anti-inflammatory drugs are potential radiation sensitizers with the mechanism of action as yet unknown. Clinical trials of the cyclooxygenase inhibitors as radiation sensitizers should explore a range of doses and evaluate potential mechanisms of action, including cyclooxygenase inhibition and other non-cyclooxygenase mechanisms.

Cyclooxygenase-2 modulates brain inflammation-related gene expression in central nervous system radiation injury

Although the contribution of cyclooxygenase-2 (COX-2) to peripheral inflammation is well documented, little is known about its role in brain inflammation. For this purpose we studied COX-2 expression in the mouse brain following ionizing radiation in vivo, as well as in murine glial cell cultures in vitro. The possible role of COX-2 in modulating brain inflammation was examined utilizing NS-398, a COX-2 selective inhibitor. Our results indicate that COX-2 is significantly induced in astrocyte and microglial cultures by radiation injury as well as in brain. Increased levels of prostaglandin E(2) in irradiated brain were reduced by NS-398. Moreover, NS-398 administration significantly attenuated levels of induction for the majority of inflammatory mediators examined, including TNFalpha, IL-1beta, IL-6, iNOS, ICAM-1, and MMP-9. In contrast, the chemokines MIP-2 and MCP-1 showed enhanced levels of induction following NS-398 administration. These results indicate that COX-2 modulates the inflammatory response in brain following radiation injury, and suggest the use of COX-2 selective inhibitors for the management of CNS inflammation.

Pronounced radiosensitization of cultured human cancer cells by COX inhibitor under acidic microenvironment

PURPOSE

To demonstrate the influence of pH on the cytotoxicity and radiosensitization by COX (cyclooxygenase) -1 and -2 inhibitors using established human cancer cells in culture.

METHODS AND MATERIALS

Nonselective COX inhibitor, ibuprofen (IB), and selective COX-2 inhibitor, SC-236, were used to determine the cytotoxicity and radiosensitization at varying pH of culture media. Human colon carcinoma cell line (HT-29) was exposed to the drug alone and in combination with radiation at different pH of the cell culture media. The end point was clonogenic ability of the single-plated cells after the treatment.

RESULTS

Cytotoxicity and radiosensitization of IB increased with higher drug concentration and longer exposure time. The most significant radiosensitization was seen with IB (1.5 mM) for 2-h treatment at pH 6.7 before irradiation. The dose-modifying factor as defined by the ratio of radiation doses required to achieve the same effect on cell survival was 1.8 at 10% survival level. In contrast, SC-236 (50 microM for 2-8 h) showed no pH-dependent cytotoxicity. There was modest increase in the cell killing at lower doses of radiation.

CONCLUSION

An acidic pH was an important factor affecting the increased cytotoxicity and radiosensitization by ibuprofen. Radiation response was enhanced at shoulder portion of the cell survival curve by selective COX-2 inhibitor.

Cyclooxygenase-2: a novel molecular target for the prevention and treatment of head and neck cancer

Cyclooxygenase-2 (COX-2), an enzyme that catalyzes the synthesis of prostaglandins, is overexpressed in a variety of premalignant and malignant conditions, including oral leukoplakia and squamous cell carcinoma of the head and neck. Increased levels of COX-2 may contribute to carcinogenesis by modulating xenobiotic metabolism, apoptosis, immune surveillance, and angiogenesis. In experimental models, newly developed selective COX-2 inhibitors suppress the formation of tumors, including tongue cancer. These findings provided a rationale for a number of chemoprevention trials that are underway. Selective COX-2 inhibitors also suppress the growth and metastases of established tumors and enhance the anticancer activity of both radiotherapy and chemotherapy in experimental animals. In this review, evidence is presented that inhibition of COX-2 represents a promising strategy to prevent or possibly treat human head and neck cancers.

Overexpression of cyclooxygenase-2 is associated with a poor prognosis in patients with squamous cell carcinoma of the uterine cervix treated with radiation and concurrent chemotherapy

BACKGROUND

The objective of this study was to determine whether cyclooxygenase-2 (COX-2) overexpression was an indicator of prognosis in patients with International Federation of Gynecology and Obstetrics (FIGO) Stage IIB uterine cervical carcinoma who underwent radiation and concurrent chemotherapy.

METHODS

Seventy-five patients with FIGO Stage IIB squamous cell carcinoma (SCC) of the uterine cervix who were treated with radiotherapy and concurrent chemotherapy between 1991 and 1996 were divided into two groups according to their COX-2 level in an immunohistochemical study: the COX-2 negative group (n = 54 patients) and the COX-2 positive group (n = 21 patients). The clinicopathologic features, patterns of treatment failure, and survival data for patients in the COX-2 positive group were compared with data from the patients in the COX-2 negative group. Univariate and multivariate analyses were performed to determine the prognostic factors that influenced patient survival.

RESULTS

In the immunohistochemical study, COX-2 overexpression was observed in approximately 30% of patients with FIGO Stage IIB SCC of the uterine cervix. With delayed regression to the initial treatment, the treatment failure rate of patients in the COX-2 positive group was much higher compared with the treatment failure rate of patients in the COX-2 negative group. The higher incidence of central failure and lymph node failure for patients in the COX-2 positive group was statistically significant (48% for the COX-2 positive group vs. 13% for the COX-2 negative group). However, there was no difference in the incidence of hematogenous metastases between the two groups (5% for the COX-2 positive group vs. 7% for the COX-2 negative group). In addition, increased COX-2 expression in tumor cells also was correlated with a shorter interval to tumor recurrence (median interval to recurrence, 9 months in the COX-2 positive group vs. 26 months in the COX-2 negative group). Compared with patients in the COX-2 negative group, patients in the COX-2 positive group had lower overall actuarial and disease free survival rates (overall 5-year actuarial survival rates: 56% for the COX-2 positive group vs. 94% for the COX-2 negative group; P = 0.003). Univariate and multivariate analyses showed that COX-2 overexpression was an independent prognostic factor that surpassed other well-known clinicopathologic parameters.

CONCLUSIONS

COX-2 overexpression can be used as a potent molecular risk factor in patients with FIGO Stage IIB SCC of the uterine cervix who are treated with radiotherapy and concurrent chemotherapy.

Cyclo-oxygenase inhibition reduces tumour growth and metastasis in an orthotopic model of breast cancer

The effect of selective and non-selective cyclo-oxygenase inhibition on tumour growth and metastasis in an orthotopic model of breast cancer was investigated. 4T1 mammary adenocarcinoma cells were injected into the mammary fat pad of female BALB/c mice. When tumours reached a mean tumour diameter of 8.4+/-0.4 mm, mice were randomised into three groups (n=6 per group) and received daily intraperitoneal injections of the selective cyclo-oxygenase-2 inhibitor, SC-236, the non selective cyclo-oxygenase inhibitor, Indomethacin, or drug vehicle. Tumour diameter was recorded on alternate days. From 8 days after initiation of treatment, tumour diameter in animals treated with either SC-236 or indomethacin was significantly reduced relative to controls. Both primary tumour weight and the number of lung metastases were significantly reduced in the SC-236 and indomethacin treated mice. Microvessel density was reduced and tumor cell apoptosis increased in the primary tumour of mice treated with either the selective or non-selective cyclo-oxygenase inhibitor. In vitro, cyclo-oxygenase inhibition decreased vascular endothelial growth factor production and increased apoptosis of tumour cells. Our results suggest that cyclo-oxygenase inhibitors will be of value in the treatment of both primary and metastatic breast cancer.

Chemoradiation with novel agents for rectal cancer

Surgery remains the mainstay of treatment for colorectal cancer. Although the role of radiation therapy in colon cancer is unclear, its role in the management of locally advanced rectal cancer has been extensively studied in clinical trials. The use of postoperative chemoradiotherapy has been shown to improve local control and disease-free survival in patients with locally advanced disease over surgery alone; however, an overall survival advantage remains unproven. Clinical trials evaluating preoperative radiotherapy have demonstrated an improved local control as well as a survival advantage. Randomized studies comparing preoperative versus postoperative combined-modality approaches have failed in the United States, mainly due to the perceived advantages of preoperative treatment: improved patient tolerance, tumor downstaging, and fewer treatment-related complications. While 5-fluorouracil-based chemotherapy remains the standard systemic agent used along with radiation, other novel agents and strategies have recently been developed and are under investigation. In this review, we discuss the use of novel anticancer agents in combination with radiation therapy for the treatment of locally advanced rectal cancer.

Docetaxel/Radiation Combinations: Rationale and Preclinical Findings

Concurrent chemoradiotherapy, administration of chemotherapeutic agents during the course of radiation therapy, has increasingly been used for treatment of advanced locoregional cancer. Improvements in radiation therapy are achieved through independent cytotoxic action of drugs and their ability to sensitize tumor cells to radiation. Laboratory investigations showed that docetaxel is potent in both of these actions. The drug increased the radiosensitivity of in vitro cultured cells and the in vivo tumor radioresponse. In contrast to exerting a strong enhancement of tumor radioresponse, the ability of docetaxel to modify normal tissue radiation damage was much lower. Thus, docetaxel can significantly increase therapeutic gain when combined with radiation therapy. The initial rationale for using docetaxel and other taxanes as radiation enhancers was the ability of these agents to arrest cells in the radiosensitive G2/M phases of the cell cycle. Additional mechanisms were subsequently detected, including the ability of docetaxel to eliminate radioresistant S-phase cells, cause tumor reoxygenation, stimulate antitumor immune resistance mechanisms, and possibly inhibit tumor angiogenesis. Because combined chemoradiotherapy treatments are limited by normal tissue toxicity, additional treatment strategies are needed to improve the antitumor efficacy and to minimize normal tissue toxicity. In this regard, many research avenues are being explored, particularly the possibility of combining chemoradiotherapy with molecular targeting. This overview addresses the rationale for major findings on the interaction of docetaxel and radiation in preclinical models and discusses how these findings may impact practical use of chemoradiotherapy.

Therapy for stage IIIB and stage IV non-small cell lung cancer

The treatment options for unresectable stage III NSCLC include definitive RT, chemotherapy, combined chemoradiotherapy, or supportive care. Compared with radiation alone or chemotherapy alone, the combination of chemotherapy and standard RT confers a modest survival benefit at the cost of increased toxicity for patients with an excellent performance status. For metastatic disease, combination chemotherapy--in particular, platinum-based regimens--improves symptom control and survival. Newer chemotherapeutic agents with higher response rates and favorable toxicity profiles are improving outcome even for the elderly and debilitated patients and those refractory to first-line chemotherapy. Evolving understanding of the molecular events in tumorigenesis is uncovering a host of promising targets for mechanism-based therapy. Many of these novel target modulators likely will require combination with conventional chemotherapy for optimal results.