Antagonistic Effects of CAPE (a Component of Propolis) on the Cytotoxicity and Genotoxicity of Irinotecan and SN38 in Human Gastrointestinal Cancer Cells In Vitro

The incidence of gastrointestinal cancers is increasing every year. Irinotecan (CPT-11), a drug used in the treatment of colorectal cancer and gastric cancer, is metabolized by carboxylesterases to an active metabolite, SN-38, which is more cytotoxic. CAPE (caffeic acid phenethyl ester) is an active component of propolis, which has a high antibacterial, antiviral, and antineoplastic potential. This study analyses the impact of CAPE on the cytotoxic (MTT assay), genotoxic (comet assay) and proapoptotic (caspase-3/7 activity) potential of irinotecan and its metabolite SN-38 in cultures of gastrointestinal neoplastic cells (HCT116, HT29, AGS). Cytotoxicity and genotoxicity activities of these compounds were carried out in comparison with human peripheral blood lymphocytes (PBLs) in vitro. The antioxidant potential of CAPE was investigated in relation H₂O₂-induced oxidative stress in the both neoplastic cells and PBLs. CAPE expressed cytotoxic, genotoxic, and pro-apoptotic activity against AGS, HCT116, and HT29 tumor cells. CAPE, in the presence of different concentrations of irinotecan or SN38, decreased the cytotoxicity, genotoxicity, and pro-apoptotic activity in these cell lines, but it has no such action on normal human peripheral blood lymphocytes.

Anti-VEGF therapy: a new approach to colorectal cancer therapy

The purpose of this review is to discuss the inhibition of vascular endothelial growth factor as a treatment for advanced colorectal cancer. The review will begin by summarizing the theory behind vascular endothelial growth factor inhibition and how this affects tumor angiogenesis. The major clinical trials that have examined antivascular endothelial growth factor agents to treat patients with advanced colorectal cancer will then be described. Finally, there is a commentary regarding the status of targeted agents currently in development for the treatment of advanced colorectal cancer and a discussion of the potential future considerations for the use of antivascular endothelial growth factor agents in clinical practice.

Randomized clinical trials for colorectal cancer peritoneal surface malignancy

Upwards of 40% of patient with colorectal cancer develop peritoneal carcinomatosis (CRCPC). Of the 2500 patients reported in the literature, 1000 underwent cytoreductive surgery (CRS) plus hyperthermic intraperitoneal chemotherapy (HIPEC), resulting in median survival of 22 to 63 months. However, level I data from prospective randomized trials are limited. Further trials are indicated to identify peritoneal carcinomatosis in at-risk patients early in the natural history of the disease and confirm the efficacy of multimodality therapy (CRS/HIPEC/systemic therapy) in those with CRCPC amenable to CRS in the modern era of novel targeted and cytotoxic systemic therapy.

Progress in metastatic colorectal cancer: growing role of cetuximab to optimize clinical outcome

The prognosis of metastatic colorectal cancer remains poor despite advances made in recent years, particularly with new treatments directed towards molecular targets. Cetuximab, a chimeric immunoglobulin (Ig)G1 monoclonal antibody that targets the ligand-binding domain of the epidermal growth factor receptor (EGFR), is active in metastatic colorectal cancer. As an IgG1 antibody, cetuximab may exert its antitumour efficacy through both EGFR antagonism and antibody-dependent cell-mediated cytotoxicity. The benefits of cetuximab in metastatic colorectal cancer are well documented in clinical trials and are acknowledged in the approval and licensing of this agent. There is evidence of the role of cetuximab not only in irinotecan-refractory or heavily pretreated patients, but also of the efficacy and safety of the addition of this agent to FOLFIRI (irinotecan/5-fluorouracil/leucovorin) in first-line metastatic colorectal cancer, with an enhanced effect in 5-fluorouracil patients with Kirsten rat sarcoma (KRAS) wild-type tumours. In these patients, a recent meta-analysis of the pooled Cetuximab Combined with Irinotecan in First-Line Therapy for Metastatic Colorectal Cancer (CRYSTAL) and Oxaliplatin and Cetuximab in First-Line Treatment of mCRC (OPUS) patient populations confirms that the addition of cetuximab to first-line chemotherapy achieves a statistically significant improvement in the best overall response, overall survival time, and progression-free survival (PSF) compared with chemotherapy alone. In nonresectable colorectal liver metastases, cetuximab plus FOLFOX-6 (oxaliplatin/5-fluorouracil/leucovorin) or cetuximab plus FOLFIRI increased significantly resectability of liver metastases, including R0 resections. Also, preliminary data indicate that cetuximab can be administered in a more convenient 2-week schedule in combination with standard chemotherapy. Cetuximab is generally well tolerated. Acne-form rash is the most frequent toxicity. Up to the present time, the results obtained with targeted therapy combinations are not as encouraging as initially expected. The identification of biomarkers associated with disease control, including KRAS and BRAF mutation status in patients treated with cetuximab, is changing the current management of metastatic colorectal cancer. Clinical and molecular predictive markers of response are under active evaluation in order to better select patients who could benefit from cetuximab treatment, with the aim of both optimising patient outcomes and avoiding unnecessary toxicities.

A phase I study of capecitabine, irinotecan, celecoxib, and radiation as neoadjuvant therapy of patients with locally advanced rectal cancer

OBJECTIVES

We conducted a prospective phase I trial to determine the maximum tolerated dose of capecitabine and irinotecan when used in combination with celecoxib and radiation as preoperative therapy for patients with locally advanced rectal cancer.

METHODS

Patients with histologic diagnosis of adenocarcinoma of distal rectum, evidence of T3/T4 tumor or nodal involvement by endorectal ultrasound/magnetic resonance imaging, any T status where tumor was close to but not involving the sphincter requiring abdominoperineal resection were evaluated by standard phase I methodology. Starting chemotherapy dosage (dose level: 0) was capecitabine 550 mg/m bid, day 1 to 5 every week through out x-ray therapy, irinotecan 30 mg/ m IV on days 1, 8, 22, 29 (no treatment on day 15 and day 36), and celecoxib 400 mg PO bid from day 1 till the last day of radiation. Radiation dosage of 50.4 Gy in 28 fractions was delivered in 5.6 weeks. If no dose limiting toxicity was observed, dose of capecitabine was escalated by 75 mg/m and irinotecan by 5 mg/m. Celecoxib dosage was fixed.

RESULTS

Fourteen patients were accrued. Dose limiting toxicity was observed at level 2 and was primarily hematological and gastrointestinal. Two patients at level 2 developed grade-3 diarrhea and thrombocytopenia and 1 patient at level 2 developed grade 3/4 vomiting, diarrhea and dehydration.

CONCLUSIONS

Recommended dosage for future trials is capecitabine 625 mg/m bid, irinotecan 35 mg/m, and celecoxib 400 mg orally bid in combination with pelvic radiation.

Chemotherapy in elderly patients with colorectal cancer

Significant advancements in chemotherapy for metastatic colorectal cancer (mCRC) have been achieved over the past decade, and the median overall survival duration is now close to 24 months with appropriate treatment. The most widely recommended chemotherapy regimens are based on the use of irinotecan or oxaliplatin in combination with 5-fluorouracil and leucovorin; some data suggest further benefit with the addition of the targeted agents bevacizumab or cetuximab. Colorectal cancer primarily affects the elderly; however, much of the defining clinical research in this field has excluded subjects of advanced age or with a poor performance status, making it difficult for clinicians to interpret current treatment paradigms for their older patients. Most clinical trials that have included elderly patients document similar survival rates and toxicity profiles to those seen in younger patients. Moreover, survey data suggest that >70% of elderly patients with cancer are willing to undergo strong, palliative chemotherapy. While these findings suggest that age itself should not determine candidacy for chemotherapy, it is important to note the great heterogeneity of the elderly population with regard to overall health, independence, and performance status. The use of a comprehensive geriatric assessment is recommended to evaluate chemotherapy appropriateness. The management of frail elderly patients and those with a short life expectancy should be focused on palliation, while fit elderly patients can receive aggressive therapy in a similar fashion to younger patients.

Current and emerging therapies for metastatic colorectal cancer: applying research findings to clinical practice

PURPOSE

The results of clinical trials that led to modern first- and second-line chemotherapeutic regimens for metastatic colorectal cancer, including studies of recently introduced monoclonal antibody products that target vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR), are described, as well as new therapeutic targets being studied and challenges in research to identify and evaluate new therapies.

SUMMARY

Modern chemotherapy regimens for first-line treatment of metastatic colorectal cancer contain fluorouracil, leucovorin, either oxaliplatin or irinotecan, and the VEGF inhibitor bevacizumab. The EGFR inhibitors cetuximab and panitumumab currently are reserved for second- or third-line therapy, but their role could change as the results of clinical research become available. The phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin pathway, src kinases, and insulin-like growth factor-1 receptor are among the targets of current research. Identifying the subset of patients with metastatic colorectal cancer who stand to benefit from a particular therapy presents a challenge in conducting clinical research.

CONCLUSION

Modern chemotherapeutic and monoclonal antibody regimens have improved survival in patients with meta-static colorectal cancer. The optimal combinations, timing, and sequence of agents remain to be determined.

Celecoxib pre-treatment in human colorectal adenocarcinoma patients is associated with gene expression alterations suggestive of diminished cellular proliferation

Cancer cells treated with the cyclooxygenase-2 inhibitor celecoxib show growth inhibition and induced apoptosis. This study was conducted to determine if the same processes are relevant to celecoxib's effects on human colorectal adenocarcinomas treated in vivo. A cohort of 23 patients with primary colorectal adenocarcinomas was randomised to receive a 7-d course of celecoxib (400mg b.i.d.) or no drug prior to surgical resection. Gene expression profiling was performed on resected adenocarcinomas from the cohort of patients. Using fold change (>1.5) and p-value (<0.05) cut-offs, 190 genes were differentially expressed between adenocarcinomas from patients receiving celecoxib and those that did not. The celecoxib pre-treated samples showed decreased expression levels in multiple genes involved in cellular lipid and glutathione metabolism; changes associated with diminished cellular proliferation. Celecoxib pre-treatment for 7 d in vivo is associated with alterations in colorectal adenocarcinoma gene expression which are suggestive of diminished cellular proliferation.

Eicosanoid modulation in advanced lung cancer: cyclooxygenase-2 expression is a positive predictive factor for celecoxib + chemotherapy--Cancer and Leukemia Group B Trial 30203

PURPOSE

Increased expression of eicosanoids in cancer has been associated with adverse prognosis. We performed a randomized phase II trial to test the hypothesis that inhibitors of two eicosanoid pathways (cyclooxygenase-2 [COX-2], celecoxib and 5-lipoxygenase [5-LOX], zileuton) added to chemotherapy would improve outcome in advanced non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Patients with advanced NSCLC, a performance status of 0 to 2, and no prior therapy were eligible. All patients received carboplatin area under the curve (AUC) 5.5 mg/mL x min day 1 + gemcitabine (1,000 mg/m(2)) days 1 and 8. Patients were randomly assigned to: (a) zileuton 600 mg PO qid, (b) celecoxib 400 mg PO bid, or (c) celecoxib and zileuton at the same doses. Immunohistochemical staining for COX-2 and 5-LOX was performed without knowledge of outcomes.

RESULTS

One hundred forty patients were entered and 134 were eligible and treated. There was no survival difference between the arms. COX-2 expression was a negative prognostic marker for overall survival (OS; hazard ratio [HR] = 2.51, P = .019 for index >or= 4; HR = 4.16, P = .005 for index = 9) for patients not receiving celecoxib. Patients with increased COX-2 expression (index >or= 4), receiving celecoxib had better survival than did COX-2-expressing patients not receiving drug (HR = .342, P = .005 for OS; HR = .294, P = .002 for failure-free survival). Multivariate analysis confirmed the interaction of COX-2 and celecoxib on survival. 5-LOX expression was neither prognostic nor predictive.

CONCLUSION

This study failed to demonstrate the value of dual eicosanoid inhibition or benefit from either agent alone in addition to chemotherapy. However, a prospectively defined subset analysis suggests an advantage for celecoxib and chemotherapy for patients with moderate to high COX-2 expression.

Phase I/II study of 24-hour infusion of irinotecan combined with oral UFT for metastatic colorectal cancer

BACKGROUND

To evaluate the efficacy and safety of irinotecan combined with UFT for untreated and pretreated metastatic colorectal cancer.

METHODS

Escalating doses of irinotecan (80-110 mg/m(2)) were administered by 24-hour infusion on day 1. UFT was administered orally at 400 mg/m(2)/day on days 3-7 and 10-14. The treatment cycles were repeated every 2 weeks.

RESULTS

In the phase I study, the maximum tolerated dose of irinotecan was 110 mg/m(2) and the recommended dose for the phase II study was determined to be 100 mg/m(2). Thirty-five patients including 3 patients at the recommended dose in the phase I study were evaluated in the phase II study. The grade 3/4 toxicities observed were leukopenia, neutropenia, thrombocytopenia and anemia. No grade 3 or more severe nonhematological toxicities were noted. The response rate was 62.9% and the median overall survival 16.7 months.

CONCLUSIONS

A 24-hour infusion of irinotecan combined with UFT is feasible and active for metastatic colorectal cancer.

Systemic and targeted therapy for advanced colon cancer

Colorectal cancer (CRC) is the third most common malignancy and the second most common cause of cancer-related death in the USA. Prognosis is best when the disease is detected early; however, nearly two-thirds of newly diagnosed cases of CRC have lymph node involvement or metastatic disease. For years, 5-fluorouracil (FU)-based regimens represented the only viable treatment option for patients with metastatic CRC. However, in recent years several newer agents have been added to the treatment arsenal for this disease. These agents include oxaliplatin, irinotecan and newer monoclonal antibodies targeting the epidermal growth factor receptor (cetuximab and panitumumab) and VEGF (bevacizumab). This review aims to discuss current systemic and targeted therapies for metastatic colon cancer with a focus on mechanism of action, indications, toxicity and efficacy.

Hot topics and landmark studies from the 43rd annual meeting of the American Society of Clinical Oncology

The results of several preclinical and clinical studies were reported by oncology professionals at the 43rd American Society of Clinical Oncology (ASCO) meeting, the largest international forum in which the latest achievements in cancer research are annually presented. The central theme this year was 'Translating Research into Practice', emphasizing the goal of forging stronger links between basic research and clinical practice. This review offers a critical, summarized selection of several of the foremost studies presented at the meeting. The focus is on the findings from randomized phase III trials that, in the authors' opinion, are most likely to have an immediate effect on clinical practice.

Advances in the treatment of patients with gastric adenocarcinoma

Despite a decline in its incidence in the Western world, gastric cancer (GC) remains the fourth most frequent cancer diagnosis worldwide and is, after lung cancer, the second leading cause of death from a malignant disease globally. Based on the published literature, treatment guidelines and reports from international meetings, we here review the current treatment options for GC and discuss insights and perspectives from the latest clinical studies. The management of GC in the early stages of the disease is based on an optimal surgical resection of the primary tumor and the regional lymph nodes. However, less than one third of patients have a resectable disease at diagnosis and among those operated, more than half are not cured by surgery alone, due to a high rate of relapse. Thus, for the majority of patients, systemic cytotoxic therapy, and sometimes radiotherapy, is a treatment option both as an adjunct to surgery and in the palliative setting. Adjuvant chemotherapy offers only a marginal benefit and has not become a standard of care in the West. In North America, adjuvant chemoradiation is broadly used, shown to significantly improve overall survival, albeit with the cost of high toxicity. Furthermore, a recently reported study from the United Kingdom demonstrated a significant disease-free and survival benefit by the use of perioperative combination chemotherapy. Several chemotherapeutic agents have been tested as a palliative therapy in advanced GC including 5- fluorouracil (5-FU), oral pyrimidines, platinum derivatives, anthracyclines, taxanes and camptothecans. It is now accepted that chemotherapy is better than best supportive care only and that 5-FU based combinations are more effective than monotherapy. However, the response rates have generally been moderate and there is no consensus on the optimal combination of cytotoxic agents and the potential role of more recently developed "targeted therapies".

Current role of antibody therapy in patients with metastatic colorectal cancer

In less than 10 years, the number and importance of non-surgical treatment modalities in patients with colorectal cancer (CRC) have increased dramatically, both in the adjuvant and the advanced settings. However, despite the improvement of cytotoxic therapy in CRC, many patients still develop progressive disease and unfortunately in patients with disease resistant to 5-fluorouracil/folinic acid, irinotecan and oxaliplatin, no effective cytotoxic therapy is known. The rapidly expanding knowledge in tumor biology has encouraged optimism for the possibility to find and target tumor-specific mechanisms and thereby increase both efficacy and tolerance. A great number of 'targeted drugs' are being tested in clinical trials and some of these new drugs, like bevacizumab, cetuximab and panitumumab, are available for routine use in health care. These new targeted drugs will expand the therapeutic arsenal in CRC to a great extent, but they will also add to the complexity of treatment of CRC. In this review, we summarize the current status of antibody therapy in patients with CRC.

Managing older patients with colorectal cancer

Colorectal cancer (CRC) is predominantly a disease of older persons, and our population is aging. Physicians and their older patients commonly face the dilemma of whether or not to give/receive systemic chemotherapy for CRC. Evidence supports the safety and efficacy of systemic chemotherapy in fit older patients motivated enough to enroll onto clinical trials. Conversely, frail older patients are more likely to suffer adverse outcomes when faced with stressors and may not benefit from chemotherapy. However, the majority of patients are neither fit nor frail, and current evidence is insufficient to either quantify or qualify the benefit of chemotherapy for this intermediate group of patients. Thus, treatment decisions must be individualized based on each older person's physical state (eg, their function and degree of comorbidity) and values. Despite a growing body of data, a great deal of work is still needed to establish optimal strategies to care for patients diagnosed with cancer later in life.

Bevacizumab in the treatment of colorectal cancer

Colorectal cancer is a common disease with therapy that has a proven effectiveness in the adjuvant and metastatic setting. Bevacizumab, a vascular endothelial growth factor inhibitor, is an antiangiogenesis monoclonal antibody that has benefit in response rate and overall survival when used in combination with existing metastatic colorectal cancer regimens. It is well tolerated with a few important side effects to be cognizant of, including hypertension, arterial thrombosis and bowel perforation. Existing treatment and research strategies are examining its use in the adjuvant setting or in combination with other angiogenesis inhibitors.

Bevacizumab, a humanized anti-angiogenic monoclonal antibody for the treatment of colorectal cancer

Angiogenesis is the process by which new blood vessels are created from pre-existing vessels. It is essential for the growth and development of normal cells and tissues during embryonic and neonatal development and of tumour cells. Solid tumours rely on having an extensive network of blood vessels for growth and survival. The key mediator of angiogenesis, vascular endothelial growth factor-A (VEGF-A), is critical for the growth of tumours and their subsequent metastasis and is known to initiate angiogenesis. Bevacizumab is a humanized immunoglobulin G monoclonal antibody that binds to VEGF with high specificity, thereby blocking VEGF-mediated signalling pathways and thus angiogenesis. Clinical trials have shown that bevacizumab is effective in prolonging survival in patients with metastatic colorectal cancer (CRC) when combined with standard chemotherapy. Consequently, bevacizumab has been approved in combination with 5-fluorouracil-based chemotherapy for first-line treatment of patients with metastatic CRC. Bevacizumab is generally well tolerated in most patients and does not exacerbate the adverse events associated with conventional chemotherapy. Bevacizumab-related side effects are generally manageable; however, monitoring for hypertension, gastrointestinal perforation, bleeding, proteinuria and thromboembolism is advised, especially in patients with predisposing factors. In addition to demonstrated survival benefits, the convenient dosing schedule and lack of interactions should ensure the successful integration of this novel agent into clinical practice.

Phase-II study of dose attenuated schedule of irinotecan, capecitabine, and celecoxib in advanced colorectal cancer

BACKGROUND

The cyclooxygenase-2 (COX-2) enzyme plays a major role in tumor progression and resistance to chemotherapy. A Phase-II study was undertaken to determine the activity of a dose attenuated schedule of irinotecan, capecitabine, and the COX-2 inhibitor celecoxib in patients with advanced colorectal cancer.

METHODS

The eligibility criteria included a pathologically or cytologically confirmed diagnosis of adenocarcinoma of the colon or rectum that was metastatic. Patients received a combination of irinotecan 70 mg/m2 over 30 min I.V. on days 1 and 8, capecitabine 1,000 mg/m2 twice per day orally on days 1-14, and celecoxib at a daily dose of 800 mg continuously. Cycles were repeated every 21 days.

RESULTS

Fifty-one patients were enrolled (median age 58 years; M : F 31 : 20). The objective response rate was 21/51 = 41% [95% confidence intervals (CI), 0.28-0.55]. The median time to progression was 7.7 months (95% CI, 6.2-8.6 months). Median survival time and probability of survival at 1 year were 21.2 months (95% CI, 13.8-n/a), and 75% (95% CI, 0.63-0.88), respectively. The major toxicity was Grade 3 or 4 diarrhea, seen in 24 and 10% of patients, respectively. There were no treatment related deaths.

CONCLUSIONS

The lower dose intensity of irinotecan appeared to maintain activity and improve tolerability when combined with capecitabine. The addition of celecoxib to irinotecan and capecitabine did not appear to significantly increase the activity of this doublet based on the RECIST criteria for objective response.

Highlights from the 42nd annual meeting of the American Society of Clinical Oncology

The results of approximately 3700 preclinical and clinical studies were presented at the 42nd annual meeting of the American Society of Clinical Oncology (ASCO) held 2-6 June 2006, in Atlanta, Georgia. The annual ASCO meeting is the largest forum in which oncology professionals from around the world report the latest advances in cancer research, encompassing a wide spectrum of subjects on molecular biology, prevention, diagnosis and therapy of tumours. The present report summarises some of the more important results of the studies presented at the meeting. In particular, the authors focused on findings from randomised Phase III trials that, in their opinion, are most likely to have an immediate effect on clinical practice. The top advances were grouped into four major themes (breast cancer, colorectal cancer, non-small cell lung cancer and selected presentations from the plenary session). In addition, selected Phase I and II studies on promising novel therapeutic agents were briefly described. Finally, a 'question and answer' format was adopted to report results of interesting studies on some hot topics.

Metastatic colorectal cancer

Metastatic colorectal cancer remains a public-health issue on a global scale. With development of a new generation of cytotoxic agents, survival has improved for patients with metastatic disease. How to maximize the benefit of chemotherapy with acceptable toxicity remains incompletely answered. Hepatic resection can provide a significant hope for long term survival, and a subset of patients might benefit from perioperative approaches. More recently, specific molecular processes have been targeted for therapeutic interventions, and encouraging results have been achieved using inhibitors of the Epidermal Growth Factor Receptor and the Vascular Endothelial Growth Factor.