Cancer Prevention: Strong Science and Real Medicine

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.

Pharmacoproteomic study of the natural product Ebenfuran III in DU-145 prostate cancer cells: the quantitative and temporal interrogation of chemically induced cell death at the protein level

A naturally occurring benzofuran derivative, Ebenfuran III (Eb III), was investigated for its antiproliferative effects using the DU-145 prostate cell line. Eb III was isolated from Onobrychis ebenoides of the Leguminosae family, a plant endemic in Central and Southern Greece. We have previously reported that Eb III exerts significant cytotoxic effects on certain cancer cell lines. This effect is thought to occur via the isoprenyl moiety at the C-5 position of the molecule. The study aim was to gain a deeper understanding of the pharmacological effect of Eb III on DU-145 cell death at the translational level using a relative quantitative and temporal proteomics approach. Proteins extracted from the cell pellets were subjected to solution phase trypsin proteolysis followed by iTRAQ-labeling. The labeled tryptic peptide extracts were then fractionated using strong cation exchange chromatography and the fractions were analyzed by nanoflow reverse phase ultraperformance liquid chromatography-nanoelectrospray ionization-tandem mass spectrometry analysis using a hybrid QqTOF platform. Using this approach, we compared the expression levels of 1360 proteins analyzed at ≤ 1% global protein false discovery rate (FDR), commonly present in untreated (control, vehicle only) and Eb III-treated cells at the different exposure time points. Through the iterative use of Ingenuity Pathway Analysis with hierarchical clustering of protein expression patterns, followed by bibliographic research, the temporal regulation of the Calpain-1, ERK2, PAR-4, RAB-7, and Bap31 proteins were identified as potential nodes of multipathway convergence to Eb III induced DU-145 cell death. These proteins were further verified with Western blot analysis. This gel-free, quantitative 2DLC-MS/MS proteomics method effectively captured novel modulated proteins in the DU-145 cell line as a response to Eb III treatment. This approach also provided greater insight to the multifocal and combinatorial signaling pathways implicated in Eb III-induced cell death.

Vitexin-2-O-xyloside, raphasatin and (-)-epigallocatechin-3-gallate synergistically affect cell growth and apoptosis of colon cancer cells

Cytotoxic effects of the combination of the food components vitexin-2-O-xyloside (X), raphasatin (4-methylsulphanyl-3-butenyl isothiocyanates; G) and (-)-epigallocatechin-3-gallate (E) were investigated in colon (LoVo and CaCo-2) and breast (MDA-MB-231 and MCF-7) cancer cells. Breast cancer cells were more resistant than colon cells to X, G and E inhibition. On the contrary, marked synergistic effects among X, G and E on cell growth were found in both colon cancer cells. Further analysis revealed a G0/G1 arrest of the phase cell progression and apoptosis, linked to modulation of Bax, Bcl2, caspase-9 and poly(ADP-ribose) polymerase as well as Reactive Oxygen Species (ROS) generation in both colon cancer cells, whereas apoptosis and ROS were not significantly detected in normal human lymphocytes. We conclude that the X, G and E mixture might act by mitochondrial pathway activation of apoptosis, possibly elicited by ROS and the mixture may be effective in the chemoprevention of colon cancer.

Effects of selenium supplements on cancer prevention: meta-analysis of randomized controlled trials

This meta-analysis aimed to investigate the preventive effect of selenium supplements alone on cancer as reported by randomized controlled trials (RCTs). We searched PubMed, EMBASE, and the Cochrane Library in July 2009. Of the 461 articles searched, 8 articles on 9 RCTs, which included 152,538 total participants, 32,110 in antioxidant supplement groups, and 120,428 in placebo groups, were included. In a random-effects meta-analysis of all 9 RCTs, selenium supplementation alone was found to have an overall preventive effect on cancer incidence [relative risk (RR) = 0.76; 95% confidence interval (CI) = 0.58-0.99]. Among subgroup meta-analyses, the preventive effect of selenium supplementation alone on cancer was apparently observed in populations with a low baseline serum selenium level (<125.6 ng/mL) (RR = 0.64; 95% CI = 0.53 to 0.78; I(2) = 45.5%; n = 7) and in high-risk populations for cancer (RR = 0.68; 95% CI = 0.58 to 0.80; I(2) = 41.5%; n = 8). The meta-analysis of randomized controlled trials indicates that there is possible evidence to support the use of selenium supplements alone for cancer prevention in the low baseline serum selenium level population and in the high-risk population for cancer.

Surrogate end points for median overall survival in metastatic colorectal cancer: literature-based analysis from 39 randomized controlled trials of first-line chemotherapy

PURPOSE

Our aims were to determine the correlations between progression-free survival (PFS), time to progression (TTP), and response rate (RR) with overall survival (OS) in the first-line treatment of metastatic colorectal cancer (MCRC), and to identify a potential surrogate for OS.

METHODS

Randomized trials of first-line chemotherapy in MCRC were identified, and statistical analyses were undertaken to evaluate the correlations between the end points.

RESULTS

Thirty-nine randomized controlled trials were identified containing a total of 87 treatment arms. Among trials, the nonparametric Spearman rank correlation coefficient (r(s)) between differences (Delta) in surrogate end points (DeltaPFS, DeltaTTP, and DeltaRR) and DeltaOS were 0.74 (95% CI, 0.47 to 0.88), 0.52 (95% CI, 0.004 to 0.81), 0.39 (95% CI, 0.08 to 0.63), respectively. The r(s) for DeltaPFS was not significantly different from the r(s) DeltaTTP (P = .28). Linear regression analysis was performed using hazard ratios for PFS and OS. There was a strong relationship between hazard ratios for PFS and OS; the slope of the regression line was 0.54 +/- 0.10, indicating that a novel therapy producing a 10% risk reduction for PFS will yield an estimated 5.4% +/- 1% risk reduction for OS.

CONCLUSION

In first-line chemotherapy trials for MCRC, improvements in PFS are strongly associated with improvements in OS. In this patient population, PFS may be an appropriate surrogate for OS. As a clinical end point, PFS offers increased statistical power at a given time of analysis and a significant lead time advantage compared with OS.

Phase III study of capecitabine plus oxaliplatin compared with fluorouracil and leucovorin plus oxaliplatin in metastatic colorectal cancer: a final report of the AIO Colorectal Study Group

PURPOSE

To compare the use of capecitabine plus oxaliplatin (CAPOX) with infusional fluorouracil (FU)/folinic acid plus oxaliplatin (FUFOX) as first-line therapy for patients with metastatic colorectal cancer (MCRC).

PATIENTS AND METHODS

A total of 474 patients with MCRC received either CAPOX (capecitabine 1,000 mg/m2 bid, days 1 to 14 plus oxaliplatin 70 mg/m2 days 1 and 8, repeated every 22 days) ) or FUFOX (oxaliplatin 50 mg/m2 followed by leucovorin 500 mg/m2 plus FU 2,000 mg/m2 as a 22-hour infusion days 1, 8, 15, and 22, repeated every 36 days). The primary end point was progression-free survival (PFS). Secondary end points were response rate (RR), overall survival (OS), time to treatment failure, and toxicity. The study was designed to determine noninferiority for the CAPOX regimen.

RESULTS

Median PFS was 7.1 months in the CAPOX arm and 8.0 months in the FUFOX arm (hazard ratio [HR], 1.17; 95% CI, 0.96 to 1.43; P = .117). Median OS was 16.8 months (CAPOX) and 18.8 months (FUFOX; HR, 1.12; 95% CI, 0.92 to 1.38; P = .26). Overall RRs were 48% for CAPOX (95% CI, 41% to 54%) and 54% for FUFOX (95% CI, 47% to 60%). Both regimens were generally well tolerated, although there was a significantly higher incidence of grade 2/3 hand-foot syndrome (HFS) in the CAPOX arm (P = .028).

CONCLUSION

CAPOX resulted in a slightly inferior efficacy than FUFOX. With respect to PFS, the best estimate of the HR of 1.17 was within the prespecified equivalence range. However, a relevant inferiority cannot be excluded. Both regimens were generally well tolerated but there was a significantly higher rate of grade 2/3 HFS in the CAPOX arm.

Cost-effectiveness analysis of oxaliplatin compared with 5-fluorouracil/leucovorin in adjuvant treatment of stage III colon cancer in the US

BACKGROUND

The MOSAIC trial demonstrated that oxaliplatin/5-fluorouracil/leucovorin (FU/LV) (FOLFOX4) as adjuvant treatment of TNM stage II and III colon cancer significantly improves disease-free survival compared with 5-FU/LV alone. For stage III patients the 4-year disease-free survival (DFS) was 69% in the FOLFOX4 arm vs 61% in the LV5FU2 arm, P = .002). The cost-effectiveness of FOLFOX4 in stage III patients was evaluated from a US Medicare perspective.

METHODS

By using individual patient-level data from the MOSAIC trial (median follow-up: 44.2 months), DFS and overall survival (OS) were estimated up to 4 years from randomization. DFS was extrapolated from 4 to 5 years by fitting a Weibull model and subsequent survival was estimated from life tables. OS beyond 4 years was predicted from the extrapolated DFS estimates and observed survival after recurrence. Costs were calculated from trial data and external estimates of resources to manage recurrence.

RESULTS

Patients on FOLFOX4 were predicted to gain 2.00 (95% confidence interval [CI]: 0.63, 3.37) years of DFS over those on 5-FU/LV. The predicted life expectancy of stage III patients on FOLFOX4 and 5-FU/LV was 17.61 and 16.26 years, respectively. Mean total lifetime disease-related costs were $56,300 with oxaliplatin and $39,300 with 5-FU/LV. Compared with 5-FU/LV, FOLFOX4 was estimated to cost $20,600 per life-year gained and $22,800 per quality-adjusted life-year (QALY) gained, discounting costs and outcomes at 3% per annum.

CONCLUSIONS

FOLFOX4 is likely to be cost-effective compared with 5-FU/LV in the adjuvant treatment of stage III colon cancer. The incremental cost-effectiveness ratio compares favorably with other funded interventions in oncology.

Recruiting participants to cancer prevention clinical trials: lessons from successful community oncology networks

PURPOSE/OBJECTIVES

To describe the organizational designs and task environments of community oncology networks with high accrual rates to cancer prevention clinical trials.

DESIGN

Replicated case study design; structural contingency theory.

SETTING

Local Community Clinical Oncology Programs (CCOPs) funded by the National Cancer Institute to test preventive and therapeutic interventions in community settings.

SAMPLE

Primary sample: oncology professionals affiliated with four CCOPs ranking among the top 10 in earned cancer control accrual credits in fiscal years 1999-2003. Secondary sample: oncology professionals affiliated with three CCOPs ranking among the top 10 three to four times during the study period. A total of 63 people participated in the interviews.

METHODS

Primary sample: on-site interviews with CCOP investigators, clinical research staff, and nononcology physicians. Secondary sample: telephone interviews with each CCOP's nurse administrator and at least one prevention research nurse.

MAIN RESEARCH VARIABLES

Staffing patterns, organizational processes, recruitment strategies, and environmental characteristics.

FINDINGS

All of the CCOPs employed dedicated prevention research staff. Recruitment through media publicity, mass mailings, or group information sessions worked best when prevention trials had flexible eligibility requirements and evaluated interventions with few health risks. Prevention trials evaluating agents with known toxicities in high-risk populations required more targeted recruitment through cancer screening programs, physician referral networks, and one-on-one discussions with protocol candidates.

CONCLUSIONS

High-performing CCOPs configured their structures, processes, and recruitment strategies to fit with accrual goals. They also benefited from stable and supportive task environments.

IMPLICATIONS FOR NURSING

Nurse-coordinated research networks have great potential to generate new knowledge about cancer prevention that can reduce cancer incidence and mortality significantly.

Phase II study of capecitabine, oxaliplatin, and erlotinib in previously treated patients with metastastic colorectal cancer

PURPOSE

To investigate the combination of erlotinib, capecitabine, and oxaliplatin in patients who were previously treated for metastatic colorectal cancer.

PATIENTS AND METHODS

Patients were eligible if they had metastatic colorectal cancer that progressed, were intolerant to first-line chemotherapy, or had disease recurrence within 1 year of adjuvant therapy for early-stage disease. Each 21-day cycle consisted of daily oral erlotinib at 150 mg, oral capecitabine at 1,000 mg/m2 (reduced to 750 mg/m2 after the first 13 patients) twice a day on days 1 to 14, and intravenous oxaliplatin at 130 mg/m2 on day 1.

RESULTS

Thirty-two patients were enrolled onto this phase II study. By intention-to-treat analyses, eight patients (25%) experienced a partial response and 14 patients (44%) had stable disease for at least 12 weeks. The median progression-free survival was 5.4 months and the median overall survival was 14.7 months. These results were essentially unchanged when limited to the cohort of patients (78%) who received prior irinotecan for metastatic colorectal cancer. Most common grade 3 to 4 toxicities included diarrhea (38%), nausea/emesis (19%), fatigue (16%), dehydration (16%), and dermatitis (13%); grade 3 or 4 toxicities were reduced with a lower starting dose of capecitabine.

CONCLUSION

The combination of capecitabine, oxaliplatin, and erlotinib seems to have promising activity against metastatic colorectal cancer in patients who received prior chemotherapy, with a relatively higher response rate and progression-free survival compared with previous reports of either infusional FU, leucovorin, and oxaliplatin or capecitabine and oxaliplatin in similar patient populations.

Phase III study of fluorouracil, leucovorin, and levamisole in high-risk stage II and III colon cancer: final report of Intergroup 0089

PURPOSE

In 1990, fluorouracil (FU) plus levamisole for 1 year became standard adjuvant treatment for patients with high-risk stages II and III colon cancer. Intergroup (INT) 0089 assessed the relative contributions of leucovorin and levamisole in such patients.

PATIENTS AND METHODS

From 1988 to 1992, 3,794 patients were randomly assigned. Experimental treatment consisted of one of three chemotherapy regimens: the low-dose leucovorin plus FU (Mayo Clinic; LDLV) regimen, the high-dose leucovorin plus FU (Roswell Park; HDLV) regimen, and the low-dose leucovorin plus levamisole plus FU (LDLV plus LEV) regimen, each administered for 30 to 32 weeks. The control arm was levamisole plus FU (LEV) for 1 year.

RESULTS

After a median follow-up of 10 years, of 3,561 eligible patients, 1,691 (47%) have died and 1,330 (37%) have experienced disease recurrence; 137 (10%) of those experiencing recurrence are still alive. A total of 481 patients (13%) died without evidence of recurrence, and 1,723 (48%) are alive and disease free. Although there were toxicity differences among the four arms, none was statistically superior in disease-free or overall survival.

CONCLUSION

The 6- to 8-month regimens of LDLV and HDLV without levamisole used in this trial, rather than the previous standard regimen of 12 months of LEV, have become widely used. INT-0089 has long-term follow-up of the largest clinical trial of patients with high-risk colon cancer, documenting not only the durability of the treatment effects, but also the natural history of patients with high-risk colon cancer, and analyses of treatment based on age, race, and comorbid conditions such as obesity, diabetes, and second primary cancers.

Adapting clinical trials networks to promote cancer prevention and control research

BACKGROUND

Since 1987, cancer centers and clinical cooperative groups serving as 'research bases' for the National Cancer Institute's (NCI) Community Clinical Oncology Program (CCOP) have been required to design and conduct cancer prevention and control (CP/C) clinical trials in addition to therapeutic trials. The study describes the structural and strategic adaptations that CCOP research bases have made to incorporate CP/C research into their scientific agendas and operations.

METHODS

Approaches to CP/C research in four cooperative groups with different scientific agendas were investigated: the Eastern Cooperative Oncology Group, the National Surgical Adjuvant Breast and Bowel Project, the North Central Cancer Treatment Group, and the Southwest Oncology Group. Sixty-five individual interviews with group leaders and investigators were conducted. Data were coded and thematically analyzed from transcribed interviews, observations of scientific sessions, and secondary documents.

RESULTS

The cooperative groups have tailored CP/C research programs to fit the interests, skills, and practice settings of their investigators without making significant adaptations in administrative and statistical infrastructures. Ongoing challenges include finding ways to broaden the pool of investigators designing CP/C protocols, involve more nononcologists in protocol design, and secure more stable and adequate funding for CP/C research.

CONCLUSION

The cooperative groups' experiences with CP/C research suggest that, with adequate resource investments, existing clinical research networks can expand into new areas of scientific investigation.

Chemoprevention: From research to clinical oncology

Chemoprevention is by now an emerging area of clinical oncology addressed to healthy individuals at higher risk for cancer, subjects with precancerous conditions, and patients who are at risk for a second primary cancer. The important results of large trials with various agents and the more accurate methods of risk assessment have already had implications in clinical practice. Recently, a number of compounds have shown to be clinically effective at various organ levels, often covering all the three settings of primary, secondary and tertiary prevention. There is proof today that at least 3 of the 4 'big killers' in oncology--breast, colon and prostate cancer--and oral cancer are to a certain extent preventable by chemopreventive drugs. The missing piece so far is lung cancer. The expanding molecular drug development is providing the tools for a more effective and safer molecular-targeted prevention. Combination chemoprevention and the use of agents with multiple effects are other particularly promising chemoprevention strategies.

Cancer and ageing: a nexus at several levels

Cancer is largely a disease of older people. With the relatively recent expansive growth within the geriatric population, a number of pressing biological and clinical questions that currently remain unanswered need to be addressed. These include what effect age itself has on the development or growth of cancer, and what are the benefits and risks of cancer prevention and treatment for the older person? New insights into the underlying biological processes of ageing provide a frame of reference for addressing these and other related questions.

Advances in the Biology of Lung Cancer Chemoprevention

The heavy burden of lung cancer, which includes the highest worldwide mortality of any cancer, and its resistance to standard approaches (smoking cessation, screening, and therapy), have motivated an intense interest in chemoprevention of this disease. Randomized controlled trials of agents (including retinoids, beta-carotene, and vitamin E) to prevent lung cancer have produced only disappointing clinical results to date. New, molecular-targeted approaches are advancing rapidly, however, with many promising targets and interactive signaling pathways for developing novel agents and combinatorial approaches in this setting. This promise is illustrated by recent studies of 15-hydroxyprostaglandin dehydrogenase, which plays a critical role in polyunsaturated fatty acid metabolism and (like another important target, prostacyclin) is downstream of cyclooxygenase-2. 15-hydroxyprostaglandin dehydrogenase degrades prostaglandin E2, appears to have tumor suppressor activity, and can be induced both by peroxisome proliferator-activated receptor-gamma ligands and an epidermal growth factor receptor inhibitor. Other important targets/pathways include the insulin-like growth factor axis, phosphoinositide 3-kinase pathway, cyclin D and E family members, and epigenetic events. Defining highest lung cancer risk (eg, establishing molecular risk models through long-term analyses of high-risk cohorts) will facilitate the clinical development of molecular-targeted prevention that will potentially reduce the enormous burden of lung cancer.