Phase II study of tailored chemotherapy for advanced colorectal cancer with either 5-fluouracil and leucovorin or oxaliplatin and irinotecan based on the expression of thymidylate synthase and dihydropyrimidine dehydrogenase

Nucleo(s)tide metabolism as basis for drug development; the Anne Simmonds award lecture

Aberrant metabolism of purines and pyrimidines led to development of drugs for treatment of various diseases, such as inflammatory, neurological, cardiovascular, viral infections and cancer. Purine and Pyrimidine Symposia are characterized by close interactions, leading to extensive cross-fertilization on methodology and translating not only from bench-to-bedside, but also between various disciplines such as medicinal chemistry, pharmacology, oncology, virology, rheumatology, biochemistry, pediatrics, cardiology, surgery and immunology. This background was fundamental in our studies on how to optimize application of existing drugs (5-fluorouracil [5FU], thiopurines, antifolates such as methotrexate) but also to support development of novel drugs such as gemcitabine, novel antifolates, S-1, TAS-102 and fluorocyclopentenylcytosine. Knowledge of their metabolism helped to design rational combinations such as of gemcitabine with cisplatin, one of the most widely used drug combinations for various cancers. The combination of 5FU with uridine, led to the development of triacetyluridine registered for emergency treatment of patients with lethal 5FU toxicity. Mechanisms of action were studied by careful analysis of their metabolism, using classical enzyme assays with radioactive precursors and HPLC analysis. Drug metabolism moved from manually operated HPLC systems with UV-detection for peak identification and paper rolls for quantification, to computer-operated HPLC with automatic multi-wavelength and fluorometric peak detection and more recently to ultrasensitive, highly specific mass-spectrometry-based systems. Some aspects, however, never changed; careful analysis of the results and being prepared for the unexpected. The latter actually led to the most interesting results. Investigation of (nucleoside/nucleotide) metabolism remains an exciting field of research.

Therapeutic effects of ginseng and ginsenosides on colorectal cancer

Colorectal cancer (CRC) is among the most common malignant diseases with high morbidity and mortality rates. Ginseng and its major extracts, ginsenosides, have been used in medical fields for thousands of years. In particular, their huge anti-cancer potential has drawn a great deal of attention in recent years. There is a large body of evidence that has shown that ginseng and its extracts could significantly inhibit tumor development and progression by suppressing cell proliferation, tumor growth, invasion and metastasis, inducing tumor cell apoptosis, regulating tumor-associated immune responses, and improving the therapeutic effect of chemotherapy. Notably, different subtypes of ginsenosides, even those extracted from the same ginseng, have exhibited distinct anti-cancer functions through different mechanisms. Over the past few years, a large number of studies have focused on how ginseng or various ginsenosides influence CRC development. Therefore, the roles and the potential of ginseng and ginsenosides in the treatment of CRC are summarized in this review. In addition, the biochemical properties of ginseng and ginsenosides are also briefly described.

Genomic and epigenomic biomarkers in colorectal cancer: From diagnosis to therapy

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths in the United States. Despite ongoing efforts aimed at increasing screening for CRC and early detection, and development of more effective therapeutic regimens, the overall morbidity and mortality from this malignancy remains a clinical challenge. Therefore, identifying and developing genomic and epigenomic biomarkers that can improve CRC diagnosis and help predict response to current therapies are of paramount importance for improving survival outcomes in CRC patients, sparing patients from toxicity associated with current regimens, and reducing the economic burden associated with these treatments. Although efforts to develop biomarkers over the past decades have achieved some success, the recent availability of high-throughput analytical tools, together with the use of machine learning algorithms, will likely hasten the development of more robust diagnostic biomarkers and improved guidance for clinical decision-making in the coming years. In this chapter, we provide a systematic and comprehensive overview on the current status of genomic and epigenomic biomarkers in CRC, and comment on their potential clinical significance in the management of patients with this fatal malignancy, including in the context of precision medicine.

Tailored therapy in patients treated with fluoropyrimidines: focus on the role of dihydropyrimidine dehydrogenase

Fluoropyrimidines are widely used in the treatment of solid tumors, mainly gastrointestinal, head and neck and breast cancer. Dihydropyrimidine dehydrogenase (DPD) is the rate-limiting enzyme for catabolism of 5-FU and it is encoded by DPYD gene. To date, many known polymorphisms cause DPD deficiency and subsequent increase of 5-FU toxicity. In addition, reduced inactivation of 5-FU could lead to increased 5-FU intracellular concentration and augmented efficacy of this drugs. Therefore DPD expression, particularly intratumoral, has been investigated as predictive and prognostic marker in 5-FU treated patients. There also seems to be a tendency to support the correlation between DPD expression and response/survival in patients treated with fluoropyrimidine even if definitive conclusions cannot be drawn considering that some studies are conflicting. Therefore, the debate on intratumoral DPD expression as a potential predictor and prognostic marker in patients treated with fluoropyrimidines is still open. Four DPD-polymorphisms are the most relevant for their frequency in population and clinical relevance. Many studies demonstrate that treating a carrier of one of these polymorphisms with a full dose of fluoropyrimidine can expose patient to a severe, even life-threatening, toxicity. Severe toxicity is reduced if this kind of patients received a dose-adjustment after being genotyped. CPIC (Clinical Pharmacogenetics Implementation Consortium) is an International Consortium creating guidelines for facilitating use of pharmacogenetic tests for patient care and helps clinicians ensuring a safer drug delivery to the patient. Using predictive DPD deficiency tests in patients receiving 5FU-based chemotherapy, in particular for colorectal cancer, has proven to be a cost-effective strategy.

Predictive Biomarkers in Metastatic Colorectal Cancer: A Systematic Review

PURPOSE

The development and use of predictive biomarkers to guide treatment decisions are paramount not only for improving survival in patients with metastatic colorectal cancer (mCRC), but also for sparing them from unnecessary toxicity and reducing the economic burden of expensive treatments. We conducted a systematic review of published studies and evaluated the predictive biomarker landscape in the mCRC setting from a molecular and clinical viewpoint.

METHODS

Studies analyzing predictive biomarkers for approved therapies in patients with mCRC were identified systematically using electronic databases. Preclinical studies and those providing no relevant information were excluded.

RESULTS

A total of 173 studies comprising 148 biomarkers were selected for final analysis. Of all the biomarkers analyzed, 1.4% (two of 148) were explored in a prospective manner, whereas 98.6% (146 of 148) were evaluated in retrospective studies. Of the latter group, 78.8% (115 of 146) were not tested in subsequent phases, 9.6% (14 of 146) were tested in other retrospective cohorts, 8.9% (13 of 146) were retrospectively tested in at least one or more randomized cohorts, and only 2.7% (four of 146) were prospectively tested in a clinical trial. Finally, only 1.4% (two of 148) were validated sufficiently and are recognized as biomarkers for guiding treatment decision making in patients with mCRC. These markers were RAS mutational status for anti-EGFR antibodies and microsatellite instability status for anti-programmed cell death-1 drugs.

CONCLUSION

Despite notable efforts to identify predictive biomarkers for various therapies used in the mCRC setting, because of a lack of data beyond retrospective studies and successful biomarker-driven approaches, only two molecular biomarkers have thus far found their translation into the clinic, highlighting the imperative need for implementing novel strategies and additional research in this clinically important field.

Role of genomic factors beyond thymidylate synthase in the prediction of response to 5-fluorouracil

5-Fluorouracil (5FU) is still a major drug in combinations regimens for the treatment of colorectal cancer (CRC) both in the adjuvant and palliative setting. 5FU or its oral prodrug capecitabine is usually combined with irinotecan/oxaliplatin and the novel agents bevacizumab/cetuximab. Although this improved the outcome, the overall prognosis in patients with metastasized disease is still relatively poor. Although the target for 5FU, thymidylate synthase was shown to have a predictive value, this could only predict response in a subset of patients. Given the heterogeneous and complex nature of CRC, it is likely that other aberrations can affect therapeutic response. As an alternative, we investigated Copy number alterations using oligonucleotide-based high-throughput array-comparative-genomic-hybridization (aCGH) to obtain an unbiased screening of the whole genetic spectrum. Chromosomal aberrations have been identified in 85% of CRC patients and include genomic regions harboring copy number alterations in the DNA. These alterations may change the expression of many genes and might explain the differential response to therapy as shown in recent studies with several 5FU combinations. In order to clarify new predictive parameters for 5FU, we used aCGH in a historical cohort of patients, which received treatment with single agent 5FU, and an unsupervised clustering analysis showed a statistical (p < 0.05) difference between responding and nonresponding patients. We also find that several regions showed differences between responders/non-responders, such as losses in 12p12.3-12q15 and in 18p (where TS is located) in responding patients. Genome-wide analysis may provide an additional tool to discriminate between responders and nonresponders.

Protopanaxadiol, an active ginseng metabolite, significantly enhances the effects of fluorouracil on colon cancer

In this study, we evaluated the effects of protopanaxadiol (PPD), a gut microbiome induced ginseng metabolite, in increasing the anticancer effects of a chemotherapeutic agent fluorouracil (5-FU) on colorectal cancer. An in vitro HCT-116 colorectal cancer cell proliferation test was conducted to observe the effects of PPD, 5-FU and their co-administration and the related mechanisms of action. Then, an in vivo xenografted athymic mouse model was used to confirm the in vitro data. Our results showed that the human gut microbiome converted ginsenoside compound K to PPD as a metabolite. PPD and 5-FU significantly inhibited HCT-116 cell proliferation in a concentration-dependent manner (both p < 0.01), and the effects of 5-FU were very significantly enhanced by combined treatment with PPD (p < 0.01). Cell cycle evaluation demonstrated that 5-FU markedly induced the cancer cell S phase arrest, while PPD increased arrest in G1 phase. Compared to the control, 5-FU and PPD increased apoptosis, and their co-administration significantly increased the number of apoptotic cells (p < 0.01). Using bioluminescence imaging, in vivo data revealed that 5-FU significantly reduced the tumor growth up to Day 20 (p < 0.05). PPD and 5-FU co-administration very significantly reduced the tumor size in a dose-related manner (p < 0.01 compared to the 5-FU alone). The quantification of the tumor size and weight changes for 43 days supported the in vivo imaging data. Our results demonstrated that the co-administration of PPD and 5-FU significantly inhibited the tumor growth, indicating that PPD significantly enhanced the anticancer action of 5-FU, a commonly used chemotherapeutic agent. PPD may have a clinical value in 5-FU’s cancer therapeutics.

Thymidylate synthase protein expression levels remain stable during paclitaxel and carboplatin treatment in non-small cell lung cancer

BACKGROUND

Thymidylate synthase (TS) is a potential predictive marker for efficacy of treatment with pemetrexed. The current study aimed at investigating whether TS expression changes during non-pemetrexed chemotherapy of non-small cell lung cancer (NSCLC), thus making rebiopsy necessary for deciding on pemetrexed second-line treatment.

MATERIALS AND METHODS

TS immunohistochemístry was performed on biopsies and available resection specimens from 65 NSCLC patients stage T1-3N0-2 treated with preoperative carboplatin and paclitaxel [neoadjuvant chemotherapy (NAC)-group] and from 53 NSCLC patients stage T1-4N0-1 treated with surgery without preceding chemotherapy [operation (OP)-group] that served as controls. The diagnostic biopsies and subsequent resection samples were compared in order to evaluate for change in TS expression in groups treated with and without preoperative chemotherapy.

RESULTS

No statistically significant change in TS expression was observed between diagnostic biopsies and subsequent surgical resections of primary tumors in either the OP-group (p = 0.186) or the NAC-group (p = 0.542). Primary tumors were discordant between diagnostic biopsies and resection specimens when TS expression was dichotomized into high (H score ≥ 150) and low (H score < 150), in 45 and 33% in the OP-group and NAC-group, respectively (p = 0.288). The fraction of tumors which increased (19 vs. 20%; p = 0.900) and decreased (42 vs. 23%; p = 0.095) in TS expression was equal between the OP- and the NAC-group.

CONCLUSION

The discordance observed between paired serial samples likely reflects intratumoral heterogeneity of TS expression and highlights the need of sufficient representative material for TS expression analysis if this biomarker is to be used for treatment selection. TS expression in primary tumors remained unchanged, and new biopsies for deciding on second-line pemetrexed does not seem warranted based on the current results.

Impact of excision repair cross-complementing gene 1 (ERCC1) on the outcomes of patients with advanced gastric cancer: correlative study in Japan Clinical Oncology Group Trial JCOG9912

BACKGROUND

Since the best chemotherapy regimen for each patient with advanced gastric cancer is uncertain, we aimed to identify molecular prognostic or predictive biomarkers from biopsy specimens in JCOG9912, a randomized phase III trial for advanced gastric cancer.

PATIENTS AND METHODS

Endoscopic biopsy specimens from primary lesions were collected in 445 of 704 randomized patients in JCOG9912. We measured the mRNA expression of excision repair cross-complementing group 1 (ERCC1), thymidylate synthase, dihydropyrimidine dehydrogenase, and five other genes, then, categorized them into low and high groups relative to the median, and examined whether gene expression was associated with efficacy end point.

RESULTS

Multivariate analyses showed that high ERCC1 expression [HR 1.37; 95% confidence interval (CI) 1.08-1.75; P = 0.010], performance status ≥ 1 (HR 1.45; 95% CI 1.13-1.86; P = 0.004), and number of metastatic sites ≥ 2 (HR 1.66; 95% CI 1.28-1.86; P < 0.001) were associated with a poor prognosis, and recurrent disease (versus unresectable; HR 0.75; 95% CI 0.56-1.00; P = 0.049) was associated with a favorable prognosis. None of these molecular factors were a predictive marker for choosing irinotecan plus cisplatin or 5-fluorouracil rather than S-1.

CONCLUSION

These correlative analyses suggest that ERCC1 is an independent prognostic factor for overall survival in the first-line treatment of gastric cancer.

CLINICAL TRIAL NUMBER

C000000062, www.umin.ac.jp.

Herbal medicines as adjuvants for cancer therapeutics

In the United States, many patients, including cancer patients, concurrently take prescription drugs and herbal supplements. Co-administration of prescription medicines and herbal supplements may have negative outcomes via pharmacodynamic and pharmacokinetic herb-drug interactions. However, multiple constituents in botanicals may also yield beneficial pharmacological activities. Botanicals could possess effective anticancer compounds that may be used as adjuvants to existing chemotherapy to improve efficacy and/or reduce drug-induced toxicity. Herbal medicines, such as ginseng, potentiated the effects of chemotherapeutic agents via synergistic activities, supported by cell cycle evaluations, apoptotic observations, and computer-based docking analysis. Since botanicals are nearly always administrated orally, the role of intestinal microbiota in metabolizing ginseng constituents is presented. Controlled clinical studies are warranted to verify the clinical utility of the botanicals in cancer chemoprevention.

Beyond Thymidylate Synthase and Dihydrofolate Reductase: Impact of Non-coding microRNAs in Anticancer Chemoresistance

Chemoresistance is one of the major reasons for the failure of anticancer chemotherapy in treating advanced stage cancer. The mechanism of chemoresistance to fluoropyrimidines and antifolates has been extensively investigated in the past 40 years. It has been well established that thymidylate synthase (TYMS, TS) and dihydrofolate reductase (DHFR) are two major targets for fluoropyrimidines and antifolates, respectively. The regulatory mechanism of TS and DHFR expression is rather complex involving transcriptional, post-transcriptional and translational regulations. Our recent understanding of the chemoresistance mechanism has been extended beyond the simple one target/drug view. In this review, we will focus on the recent advancement of non-coding microRNAs (miRNAs) in contributing to the regulations of TS and DHFR expression, and to the chemoresistance mechanism of fluoropyrimidines and antifolates.

Phase II study of pharmacogenetic-tailored therapy in elderly colorectal cancer patients

BACKGROUND

Retrospective analyses suggested that a pharmacogenetic approach may allow a tailored selection of chemotherapy for metastatic colorectal cancer.

AIM

We conducted a phase II study of pharmacogenetic-selected first-line chemotherapy in elderly patients with advanced colorectal cancer, with the aim to improve efficacy and to reduce toxicity in this group of patients.

METHODS

24 patients were enrolled in this study. Chemotherapy regimen was prospectively assigned based on TS, DPD, ERCC-1 and UGT1A1 genotyping results. Twelve patients (50%) were treated with modified FOLFIRI, 11 patients (46%) with modified FOLFOX6 and 1 (4%) with De Gramont regimen.

RESULTS

A partial remission was obtained in 4 cases (17%), stable disease in 8 cases (33%) and progressive disease in 12 cases (50%). Grade 3-4 neutropenia was observed in 7 patients (29%) and diarrhoea in 3 cases (12%). The trial was then interrupted according to study design requiring 13 partial remissions out of the first 24 patients enrolled as the necessary response rate level in order to continue.

CONCLUSION

Prospective selection of chemotherapy based on TS, DPD, ERCC-1 and UGT1A1 expression in elderly advanced colorectal cancer patients failed to confirm previous results. A more accurate validation of retrospective findings is warranted before these molecular markers can be used for treatment selection in the clinical practice.

Biomarkers of DNA repair and related pathways: significance in non-small cell lung cancer

PURPOSE OF REVIEW

To review selected biomarkers of DNA repair and related pathways as they relate to the management of patients with non-small cell lung cancer (NSCLC), emphasizing the role of individualized, chemotherapy for advanced disease, and discussing potential applications in early disease.

RECENT FINDINGS

The activity of molecular-targeted agents in NSCLC patients whose tumor possesses relevant biomarkers [such as epidermal growth factor receptor (EGFR) activating mutations and ALK translocations] has made personalized therapy possible. In addition, preclinical and clinical studies have shown that histopathological and biomolecular factors can correlate with clinical outcome in patients with NSCLC treated with chemotherapy. As a result, tumor histology is now routinely considered in selecting chemotherapy for NSCLC patients, such as pemetrexed for nonsquamous histology. Molecular tumor and host factors, including genes involved in DNA-repair and synthesis, are potentially even more relevant as predictive biomarkers of tumor response to chemotherapy. However, individual molecular markers and gene signatures need further validation and standardization, before routine use in the clinic can be recommended.

SUMMARY

In the era of molecular-targeted agents, individualized therapy based on molecular biomarkers has become a reality in the treatment of patients with advanced NSCLC. Further studies are needed to optimize current treatment algorithms with regard to biomarkers for chemotherapy benefit, to refine molecular markers, and to translate these findings to early stage NSCLC.

Pharmacogenetic tests in cancer chemotherapy: what physicians should know for clinical application

Significant efforts to develop pharmacogenomic predictors have been made to guide more effective and safer chemotherapy. Although a considerable amount of data has been generated from numerous experimental or clinical studies, there is a large gap between pharmacogenomic knowledge and clinical application. This review will focus on eight pharmacogenetic tests including TYMS, DPYD, UGT1A1, CYP2D6, EGFR, KRAS, FCGR3A, and BRCA1/2 to predict toxicity or response to commonly used chemotherapeutic agents. We will discuss the current level of evidence, if the current pharmacogenetic tests are appropriate for clinical application, and how to integrate the pharmacogenomic information into routine clinical practice.

Thymidine phosphorylase expression in metastatic sites is predictive for response in patients with colorectal cancer treated with continuous oral capecitabine and biweekly oxaliplatin

The primary objective of this study was to determine the activity and safety profile of biweekly oxaliplatin combined with continuous oral capecitabine in the first-line treatment of metastatic colorectal cancer. A secondary endpoint was to investigate the correlation between thymidylate synthase and thymidine phosphorylase (TP) expression in metastatic tissues and tumor response. Forty-one patients received oral capecitabine 1331 mg/m every day combined with intravenous oxaliplatin 85 mg/m every 2 weeks. The overall response rate was 58.5% [95% confidence interval (CI): 43.3-73.6%], the median progression-free survival 9.4 months (95% CI: 7.7-11.2 months) and the median survival 22.3 months (95% CI: 16.1-27.5 months). There were no grade 4 toxicities, and grade 3 toxicity was also uncommon. High TP expression in metastatic tissue was significantly associated with response to treatment (P=0.019), and also with a trend towards a better median progression-free survival and overall survival compared with patients expressing low TP (P=0.056; P=0.073). This study suggests that biweekly oxaliplatin and continuous oral capecitabine is an active and well-tolerated chemotherapy regimen in the first-line treatment of metastatic colorectal cancer. Moreover, these findings add to a growing body of evidence that patients with high levels of intratumoral TP expression are the ideal candidates for capecitabine-based chemotherapy.

XIII International Charles Heidelberger Symposium and 50 Years of Fluoropyrimidines in Cancer Therapy Held on september 6 to 8, 2007 at New York University Cancer Institute, Smilow Conference Center

This conference opened with Franco Muggia, host and principal organizer, thanking Joseph Landolph, co-Chair of the International Scientific Organizing Committee and its members (Franco Muggia, co-Chair, Max Costa, Steven Burakoff, Howard Hochster, Eliezer Huberman, John Bertram, Peter Danenberg, and Richard Moran); the members of the Local Organizing Committee (Drs. Costa, Guttenplan, Geacintov, and Hochster); and the Charles and Patricia Heidelberger Foundation for Cancer Research for developing the scientific program and for working to help him create this special symposium honoring the late Charles Heidelberger, former president of the American Association for Cancer Research, member of the National Academy of Sciences, and extraordinary scientist in the fields of carcinogenesis and cancer chemotherapy. It was most appropriate to commemorate the 50th anniversary of the patent obtained by him for 5-fluorouracil (5FU), a drug that came to symbolize the promise chemotherapy of nonhematologic malignancies. After this compound was shown to be helpful in the treatment of colorectal and breast cancers, Dr. Heidelberger proceeded to develop other fluoropyrimidines and to inspire Ph.D. students and postdoctoral fellows to investigate their mechanisms of action and to develop assays applicable to clinical specimens (what we now refer to as translational science). Steven Burakoff, director of the NYU Cancer Institute (2000 to 2008), followed with welcoming remarks. Dr. Burakoff pointed to his personal fortuitous connection to the Symposium: The famous immunologist, Michael Heidelberger, Charles' father, who was known as the Father of Immunochemistry, trained Elvin Kabat while at Columbia, who trained Baruch Benacerraf, who moved from NYU to Harvard and subsequently became Burakoff's mentor. The renowned NYU Division of Immunology carries the name Michael Heidelberger because he spent more than 30 years in the Department of Pathology at the NYU School of Medicine after retiring from Columbia University.

DNA copy number profiles of primary tumors as predictors of response to chemotherapy in advanced colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is biologically a heterogeneous disease, which may affect response to drug therapy. We investigated the correlation of genome-wide DNA copy number profiles of primary tumors with response to systemic chemotherapy in advanced CRC.

PATIENTS AND METHODS

DNA was isolated from formaldehyde-fixed paraffin-embedded primary tumors of 32 patients with advanced CRC, which were selected based on either a good response (n = 16) or a poor response (n = 16) to first-line combination therapy with capecitabine and irinotecan. High-resolution DNA copy number profiles were obtained by means of 30 K oligonucleotide-based array comparative genomic hybridization (aCGH).

RESULTS

Unsupervised hierarchical cluster analysis of the aCGH data revealed two clusters of 19 and 13 tumors, respectively, and cluster membership showed a significant correlation with response status (P < 0.03). The nonresponders had fewer chromosomal alterations compared with the responders, in particular less losses were found (P < 0.03). Most prominent differences between the two groups were losses of regions 18p11.32-q11.2 (P < 0.02) and 18q12.1-q23 (P < 0.03), which were more frequently observed in responders.

CONCLUSIONS

Differences in DNA copy number profiles of primary CRCs are associated with response to systemic combination chemotherapy with capecitabine and irinotecan. Responders overall had more chromosomal alterations, especially loss of chromosome 18.

Effect of Bupleuri Radix extracts on the toxicity of 5-fluorouracil in HepG2 hepatoma cells and normal human lymphocytes

Despite the excellent chemotherapeutic effect of 5-fluorouracil, its cytotoxicity and genotoxicity in normal cells remain a major problem. We sought to assess whether Bupleuri Radix extract enhances 5-fluorouracil-induced cytotoxicity in HepG2 hepatoma cells, while protecting normal blood lymphocytes. Bupleuri Radix, used for treatment of liver disease in oriental medicine, possesses antitumour properties; it induces apoptosis through cell arrest in tumour cells, but does not affect normal lymphocytes. In this study, we evaluated the protective and enhancing effects of Bupleuri Radix on 5-fluorouracil-induced cytotoxicity in HepG2 cells and normal lymphocytes. Treatment with Bupleuri Radix increased the micronuclei frequency and DNA damage, resulting from 5-fluorouracil treatment. However, when human lymphocytes were cotreated with Bupleuri Radix and 5-fluorouracil, the frequency of 5-fluorouracil-induced micronuclei decreased. Although the extent of 5-fluorouracil-induced DNA damage, determined by single-cell gel electrophoresis, increased after treating HepG2 cells with Bupleuri Radix, it decreased in normal lymphocytes. When cells were treated with 20 microM 5-fluorouracil and 200 microg/ml Bupleuri Radix simultaneously, Bax protein increased in HepG2 cells at 24 hr; however, p21 and p53 proteins were up-regulated in normal human lymphocytes. Cotreatment with 200 microg/ml Bupleuri Radix and 20 microM 5-fluorouracil resulted in cell arrest at the late G(1)/early S phase in HepG2 cells (55.80 +/- 0.19%) and normal lymphocytes (97.19 +/- 0.27%). In addition, Bupleuri Radix and 5-fluorouracil treatment increased mitochondria membrane potential collapse only in HepG2 cells (19.02%), while it was not changed in lymphocytes. In conclusion, our findings suggest that Bupleuri Radix may be effective as a therapeutic agent to treat hepatomas.

Progress in the development of prognostic and predictive markers for gastrointestinal malignancies

Gastrointestinal cancers remain a significant cause of morbidity and mortality. While increasing therapeutic options have improved outcomes for many patients, they have also complicated treatment decision-making. Unfortunately, most patients with advanced gastrointestinal malignancies die from their disease. Prognostic and predictive markers could improve treatment significantly by identifying patients who may or may not require a given therapy, and determining those most likely to benefit from a therapy. Candidates for such markers include blood antigens and circulating tumor cells, tumor enzyme and gene expression, and pharmacodynamic endpoints. In this review, we summarize reported and ongoing research to define and validate prognostic and predictive markers in gastrointestinal malignancies, with an emphasis on colorectal cancer and brief overview of pancreatic and neuroendocrine tumors.

Evaluating the drug-target relationship between thymidylate synthase expression and tumor response to 5-fluorouracil. Is it time to move forward?

Thymidylate synthase is a target of 5-fluoruracil, a pyrimidine analog used to treat gastrointestinal and other cancers. The 5-fluorouracil metabolite, fluoro-deoxyuridine monophosphate, forms a ternary complex with thymidylate synthase and 5,10-methylene tetrahydrofolate. The purpose of this study was to evaluate the time-honored connection between thymidylate synthase and 5-fluorouracil. From our literature search spanning reports from 1995 to 2007 published in journals having an impact factor greater than 2, we stratified the tumors within each article, according to low versus high thymidylate synthase expression. These groups were subdivided into responders, stable disease or disease progression. The relationship between thymidylate synthase expression and 5-fluorouracil response was analyzed for the overall group, as well as for subsets. Overall, the literature supported an approximately 2-fold inverse relationship between thymidylate synthase expression and response to 5-fluoruracil. We found no change in the trend for a relationship between thymidylate synthase and 5-fluorouracil when the literature was stratified by date of publication, impact factor of the journal in which the report was published, or substrate (mRNA versus protein) for measuring thymidylate synthase expression. Of note, there is no significant change in the trend when comparing 5-fluorouracil treatment alone or in combination with leucovorin. We found a decline of this trend when certain chemotherapeutics were used in combination with 5-fluorouracil. In sum, the connection between thymidylate synthase expression and patient response to 5-fluorouracil does not satisfy expectations for an effective drug-target relationship; and thus, studies of the thymidylate synthase tandem repeat status might only be clinically valuable in regards to patient toxicity. Thus, we question the reliability of thymidylate synthase expression as a clinical predictor of 5-fluorouracil response. Future research could perhaps be directed towards alternate targets and metabolites of 5-fluorouracil, in an effort to find a clinically relevant biomarker panel for response and to optimize fluoropyrimidine-based therapy.

ERCC1 mRNA levels and survival of advanced gastric cancer patients treated with a modified FOLFOX regimen

Molecular markers involved in DNA repair can help to predict survival in gastric cancer patients treated with 5-FU plus platinum chemotherapy. Excision repair cross-complementing 1 (ERCC1) and thymidylate synthase (TS) mRNA expression levels were assessed in advanced gastric cancer tumour samples using real-time quantitative PCR in 76 patients treated with a modified FOLFOX (biweekly oxaliplatin plus 5-FU and folinic acid) regimen. Median survival time in patients with low ERCC1 levels was significantly longer than in those with high levels (15.8 vs 6.2 months; P<0.0001). Patients with high TS levels had longer survival than those with low levels (12.2 vs 10.1 months; P=0.01). Forty-eight patients with low ERCC1 and high TS levels had a median survival of 16.1 months (P<0.0001). The hazard ratio for patients with high ERCC1 expression was 9.4 (P<0.0001). In patients with high mRNA levels of ERCC1, alternative chemotherapy regimens should be considered.

A randomized phase II trial of pemetrexed plus irinotecan (ALIRI) versus leucovorin-modulated 5-FU plus irinotecan (FOLFIRI) in first-line treatment of locally advanced or metastatic colorectal cancer

BACKGROUND

This multicenter, randomized trial compared overall response rate between pemetrexed plus irinotecan (ALIRI) and leucovorin-modulated 5-fluorouracil plus irinotecan (FOLFIRI) in patients with advanced colorectal cancer. Secondary objectives included overall and progression-free survival, duration of response, toxicities, and biomarkers.

PATIENTS AND METHODS

ALIRI patients received pemetrexed 500 mg/m(2) and irinotecan 350 mg/m(2) with vitamin supplementation on day 1 of each 21-day cycle. FOLFIRI patients received irinotecan 180 mg/m(2) on days 1, 15, 29; on days 1, 2, 15, 16, 29, 30, patients received leucovorin 200 mg/m(2), bolus 5-fluorouracil 400 mg/m(2), and 5-fluorouracil 600 mg/m(2) as 22-hour infusion.

RESULTS

Of 132 patients randomly assigned, 130 patients (64 = ALIRI, 66 = FOLFIRI) received > or =1 dose of treatment. Response rates (ALIRI = 20.0%, FOLFIRI = 33.3%) were not significantly different between arms (p = 0.095). Progression-free survival was 5.7 months for ALIRI and 7.7 months for FOLFIRI (p < 0.001). Neutropenia, fatigue, diarrhea, nausea, and vomiting were the major toxicities. There were 5 drug-related deaths (ALIRI = 4, FOLFIRI = 1). Biomarker analysis failed to reveal that any of the 18 preselected genes were clearly associated with tumor response.

CONCLUSIONS

Neither efficacy nor safety improved on the ALIRI arm compared to the FOLFIRI arm. Progression-free survival on FOLFIRI was significantly longer compared to ALIRI. Potential biomarkers capable of predicting response to either regimen in advanced or metastatic colorectal carcinoma need further characterization.

Drug metabolism by tumours: its nature, relevance and therapeutic implications

Drug-metabolising enzymes (DMEs) are present in tumours and are capable of biotransforming a variety of antineoplastics. Tumoural drug metabolism is both a potential mechanism of resistance and a means of achieving optimal therapy. This review addresses the classes of DMEs, their cytotoxic substrates and distribution in specific malignancies. The limitations of preclinical and clinical studies are highlighted. Their role in predicting therapeutic response, the activation of prodrugs and the potential for their modulation for gain is also addressed. The contribution of tumoural DMEs to cancer therapy can only be ascertained through large prospective studies and supported by new technologies. Only then can efforts be concentrated in the design of better prodrugs or combination therapy to optimise individual therapy.

Predictive and prognostic markers in colorectal cancer

Despite recent advances in the treatment of both early and advanced colorectal cancer, it remains the second leading cause of cancer deaths in the western world. There is, therefore, a pressing need to optimize the use of the currently available systemic therapies and to identify active new agents for the treatment of this disease. Pharmacogenomic studies have shown that genetically determined variability in key cellular functions can influence toxicity, response to treatment and survival. Numerous examples of these single ‘classical’ markers have been identified for a wide range of agents and each has been studied with regard to its effect on response. However, in any individual or tumor it is likely that a number of complex, interacting factors are involved in determining the likelihood of benefit with a given therapeutic agent. Microarray-based gene-expression profiling has allowed the complex range of molecular changes occurring in the cell and surrounding stroma to be assessed in relation to response and prognosis. Predictive gene sets have been developed and, along with other markers, are being assessed in prospective clinical trials. Treatment may soon be individualized by using this technology to predict which patients will benefit from a particular systemic therapy or which are likely to develop recurrence.

Neoadjuvant chemotherapy for patients with liver metastases from colorectal cancer

Colorectal cancer is the second most common type of cancer in industrialized countries. Despite improved resection procedures and optimized adjuvant chemotherapy, local or distant recurrences occur in 22-25% of patients with stage II/III colon cancer. Approximately 30% of patients have advanced disease at presentation. The liver is the most common site of colorectal metastases and, interestingly, 20-30% of patients with colorectal cancer have liver-only metastases. The combined modality of chemotherapy and surgery increases overall survival and the chance of cure for metastatic patients, even if there is no agreement in terms of the best schedule and how long the treatment must last. In this paper, we review the role and the rationale of neoadjuvant chemotherapy within a multimodal approach, and discuss remaining questions and future directions.

Measurement of DPD and TS transcripts aimed to predict clinical benefit from fluoropyrimidines: confirmation of the trend in Russian colorectal cancer series and caution regarding the gene referees

BACKGROUND

Measurement of intratumoral expression of dihydropyrimidine dehydrogenase (DPD) and thymidylate synthase (TS) may have some value in predicting the response to fluoropyrimidine-containing therapy.

PATIENTS AND METHODS

We attempted to validate this association in a series of Russian metastatic colorectal cancer cases. While replicating already published protocols, we unexpectedly found that the use of commonly utilized gene referees, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and beta-actin, may lead to artifacts due to pseudogene-driven amplification from the genomic DNA template. We have developed a real-time PCR protocol which amplifies short PCR fragments, thus allowing efficient analysis of archival formalin-fixed paraffin-embedded tumor samples, and relies on succinate dehydrogenase (SDHA) as a gene referee, therefore avoiding amplification from genomic DNA.

RESULTS

Low content of DPD transcripts was observed in 13/20 (65%) patients with disease control (tumor response or disease stabilization) as compared to only 3/9 (33%) subjects with progressive disease (p = 0.11). Despite the low number of patients, this association reached the level of statistical significance when similar analysis was done for TS expression (11/20 (55%) vs. 1/9 (11%); p = 0.03).

CONCLUSIONS

Our data confirm that low DPD and TS expressors have higher chances of success of fluoropyrimidine-containing regimens.

Changes in the status of p53 affect drug sensitivity to thymidylate synthase (TS) inhibitors by altering TS levels

Colorectal cancer (CRC) resistance to fluoropyrimidines and other inhibitors of thymidylate synthase (TS) is a serious clinical problem often associated with increased intracellular levels of TS. Since the tumour suppressor gene p53, which is mutated in 50% of CRC, regulates the expression of several genes, it may modulate TS activity, and changes in the status of p53 might be responsible for chemoresistance. Therefore, this study was aimed to investigate TS levels and sensitivity to TS inhibitors in wild-type (wt) and mutant (mt) p53 CRC cells, Lovo and WiDr, respectively, transfected with mt and wt p53. Lovo 175X2 cells (transfected with mt p53) were more resistant to 5-fluorouracil (5-FU; 2-fold), nolatrexed (3-fold), raltitrexed (3-fold) and pemetrexed (10-fold) in comparison with the wt p53 parental cells Lovo 92. Resistance was associated with an increase in TS protein expression and catalytic activity, which might be caused by the loss of the inhibitory effect on the activity of TS promoter or by the lack of TS mRNA degradation, as suggested by the reversal of TS expression to the levels of Lovo 92 cells by adding actinomycin. In contrast, Lovo li cells, characterized by functionally inactive p53, were 3-13-fold more sensitive to nolatrexed, raltitrexed and pemetrexed, and had a lower TS mRNA, protein expression and catalytic activity than Lovo 92. However, MDM-2 expression was significantly higher in Lovo li, while no significant differences were observed in Lovo 175X2 cells with respect to Lovo 92. Finally, mt p53 WiDr transfected with wt p53 were not significantly different from mt p53 WiDr cells with respect to sensitivity to TS inhibitors or TS levels. Altogether, these results indicate that changes in the status of p53, can differently alter sensitivity to TS inhibitors by affecting TS levels, depending on activity or cell line, and might explain the lack of clear correlation between mutations in p53 and clinical outcome after chemotherapy with TS inhibitors.

Mechanism of trifluorothymidine potentiation of oxaliplatin-induced cytotoxicity to colorectal cancer cells

Oxaliplatin (OHP) is an anticancer agent that acts by formation of Platinum-DNA (Pt-DNA) adducts resulting in DNA-strand breaks and is used for the treatment of colorectal cancer. The pyrimidine analog trifluorothymidine (TFT) forms together with a thymidine phosphorylase inhibitor (TPI) the anticancer drug formulation TAS-102, in which TPI enhances the bioavailability of TFT in vivo. In this in vitro study the combined cytotoxic effects of OHP with TFT were investigated in human colorectal cancer cells as a model for TAS-102 combinations. In a panel of five colon cancer cell lines (WiDr, H630, Colo320, SNU-C4 and SW1116) we evaluated the OHP-TFT drug combinations using the multiple drug–effect analysis with CalcuSyn software, in which the combination index (CI) indicates synergism (CI<0.9), additivity (CI=0.9–1.1) or antagonism (CI>1.1). Drug target analysis was used for WiDr, H630 and SW1116 to investigate whether there was an increase in Pt-DNA adduct formation, DNA damage induction, cell cycle delay and apoptosis. Trifluorothymidine combined with OHP resulted in synergism for all cell lines (all CI<0.9). This was irrespective of schedule in which either one of the drugs was kept at a constant concentration (using variable drug ratio) or when the two drugs were added in a 1 : 1 IC₅₀-based molar ratio. Synergism could be increased for WiDr using sequential drug treatment schedules. Trifluorothymidine increased Pt-DNA adduct formation significantly in H630 and SW1116 (14.4 and 99.1%, respectively; P<0.05). Platinum-DNA adducts were retained best in SW1116 in the presence of TFT. More DNA-strand breaks were induced in SW1116 and the combination increased DNA damage induction (>20%) compared with OHP alone. Exposure to the drugs induced a clear cell-cycle S-phase arrest, but was dose schedule and cell line dependent. Trifluorothymidine (TFT) and OHP both induced apoptosis, which increased significantly for WiDr and SW1116 after TFT–OHP exposure (18.8 and 20.6% respectively; P<0.05). The basal protein levels of ERCC1 DNA repair enzyme were not related to the DNA damage that was induced in the cell lines. In conclusion, the combination of TFT with the DNA synthesis inhibitor OHP induces synergism in colorectal cancer cells, but is dependent on the dose and treatment schedule used.

Changes to the dihydropyrimidine dehydrogenase gene copy number influence the susceptibility of cancers to 5-FU-based drugs: Data mining of the NCI-DTP data sets and validation with human tumour xenografts

Patient response to the anti-tumour drug 5-fluorouracil (5-FU) is variable, but predicting the response rate is important for the selection of effective chemotherapy. Our aim was to identify alterations in DNA copy number that influence susceptibility of cancer cells to 5-FU-based drugs. The NCI public database was used to identify chromosome loci associated with drug sensitivity and DNA copy number. One of the 11 candidates, the cytogenetic band 1p21.3, harbours the dihydropyrimidine dehydrogenase (DPD) gene. To validate this finding, the DPD copy number and in vivo sensitivity to 5-FU-based drugs were determined in 31 human tumour xenografts. Those xenografts demonstrating low sensitivity had significantly higher DPD copy numbers than highly sensitive tumours (P<0.002). Moreover, DPD mRNA expression levels were significantly correlated with DPD copy numbers (P<0.046). An assessment of copy number may be a more precise method of predicting the sensitivity of cancer patients to 5-FU related drugs.

Molecular-based choice of cancer therapy: realities and expectations

Current choice of cancer therapy is usually empirical and relies mainly on the statistical prediction of the treatment success. Molecular research provides some opportunities to personalize antitumor treatment. For example, life-threatening toxic reactions can be avoided by the identification of subjects, who carry susceptible genotypes of drug-metabolizing genes (e.g. TPMT, UGT1A1, MTHFR, DPYD). Tumor sensitivity can be predicted by molecular portraying of targets and other molecules associated with drug response. Tailoring of antiestrogen and trastuzumab therapy based on hormone and HER2 receptor status has already become a classical example of customized medicine. Other predictive markers have been identified both for cytotoxic and for targeted therapies, and include, for example, expression of TS, TP, DPD, OPRT, ERCC1, MGMT, TOP2A, class III beta-tubulin molecules as well as genomic alterations of EGFR, KIT, ABL oncogenes.

Simple combinations of 5-FU pathway genes predict the outcome of metastatic gastric cancer patients treated by S-1

We evaluated the expression of 5-FU pathway genes in prechemotherapeutic fresh frozen samples obtained from primary tumors to predict response and survival of 59 metastatic gastric cancer patients treated with S-1 monotherapy as first line treatment. Five 5-FU pathway genes, including thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), orotate phosphoribosyltransferase (OPRT), thymidine phosphorylase (TP) and uridine phosphorylase (UP), were analyzed by the quantitative real-time reverse transcriptional PCR method. Median values of each gene were selected for cut-off values separating high and low gene expressions. In univariate analyses, low TS, high OPRT and low TP were significantly associated with a tumor shrinkage and a long survival, whereas DPD and UP gene expressions did not correlate with response and survival. Multivariate analyses revealed that independent variables were OPRT and TS for response and TS and TP for survival. When OPRT and TS were combined, a significantly increased accuracy rate of 91.5% was seen for response. Similarly, an increased hazard ratio of 10.29 was observed for survival in patients possessing low TS and low TP, compared with those with high TS or high TP. The simple combinations of 2 genes, OPRT and TS for response and TS and TP for survival, may allow identification of gastric cancer patients who will benefit from S-1 chemotherapy.

Drug resistance, predictive markers and pharmacogenomics in colorectal cancer

Resistance to chemotherapy limits the effectiveness of current cancer therapies, including those used to treat colorectal cancer, which is the second most common cause of cancer death in Europe and the United States. 5-Fluorouracil-based chemotherapy regimens are the standard treatment for colorectal cancer in both the adjuvant and advanced disease settings. Drug resistance is thought to cause treatment failure in over 90% of patients with metastatic cancer, while drug resistant micrometastic tumour cells may also reduce the impact of adjuvant chemotherapy treatment. The identification of panels of biomarkers that not only identify those patients most likely to benefit from chemotherapy treatment, but also which chemotherapies to use, would be a major advance. In this review, we describe molecular mechanisms of drug resistance that may be relevant to colorectal cancer. We also describe the results of predictive biomarker studies in this disease. Finally, we discuss how pharmacogenomics and other high through-put technologies may impact on the clinical management of colorectal cancer in the future.