Relationship of elevated tumour thymidine phosphorylase in node-positive breast carcinomas to the effects of adjuvant CMF

Early Adverse Events predict Survival Outcomes in HER2-positive Advanced Breast Cancer Patients treated with Lapatinib plus Capecitabine

Background: This study aimed to investigate the impact of early adverse events (AE) following the initiation of lapatinib plus capecitabine on the progression-free survival (PFS) and overall survival (OS) outcomes of human epidermal growth factor receptor 2 (HER2) positive advanced breast cancer (ABC) patients.

Methods: A secondary analysis of participants treated with lapatinib plus capecitabine, or ado-trastuzumab emtansine in the clinical trial EMILIA was conducted. Cox proportional hazard analysis was used to assess the impact of AE occurring within the first 42 days of lapatinib plus capecitabine therapy on the PFS and OS outcomes of ABC patients.

Results: The study included 488 HER2-positive (ABC) patients initiated on lapatinib plus capecitabine. Rash (Hazard Ratio (HR) [95% Confidence Interval (CI)]: Grade 1 = 0.67 [0.46-0.98], Grade 2+ = 0.71 [0.42-1.19]; p = 0.046) and hand-foot syndrome (HR [95% CI]: Grade 1 = 0.58 [0.43-0.80], Grade 2+ = 0.61 [0.43-0.86]; p = <0.001) occurring within the first 42 days of lapatinib plus capecitabine therapy were significantly associated with improved OS. Conversely, nausea and vomiting occurring within the first 42 days of lapatinib plus capecitabine therapy was significantly associated with worsened OS (HR [95% CI]: Grade 1 = 1.08 [0.82-1.42], Grade 2+ = 1.52 [1.13-2.03]; p = 0.027).

Conclusions: Rash and hand-foot syndrome occurring early after the initiation of on lapatinib plus capecitabine were significantly associated with improved OS, while early nausea and vomiting was associated with worse OS. In HER2-positive ABC patients initiating lapatinib plus capecitabine, consideration should be given to more closely monitoring patients at risk of nausea and vomiting, while rash and hand foot syndrome are AE associated with improved survival.

Thymidine phosphorylase: the unforeseen driver in colorectal cancer treatment?

5-Fluorouracil- and leucovorin-based chemotherapy regimens are the backbone of colorectal cancer treatment. The addition of oxaliplatin, irinotecan and monoclonal antibodies to this backbone has largely improved clinical outcomes, but has also led to new questions, with conflicting data frequently reported in studies. Thymidine phosphorylase (TP) is a nucleoside-metabolizing enzyme involved in 5-fluorouracil pharmacokinetics, as well as inflammatory responses, neoangiogenesis and apoptosis. TP expression is regulated by hypoxia, inflammatory cytokines and antitumoral agents. We hypothesize that TP could be the unforeseen driver in the conflicting data observed with different regimens commonly used in colorectal cancer treatment. Greater comprehension of the role of this enzyme in tumor progression and pyrimidine metabolism may lead to more accurate, patient-tailored therapy.

Assessing Tumor Angiogenesis in Histological Samples

Tumor neovascularization acquires their vessels through a number of processes including angiogenesis, vasculogenesis, vascular remodeling, intussusception, and possibly vascular mimicry in certain tumors. The end result of the tumor vasculature has been quantified by counting the number of immunohistochemically identified microvessels in areas of maximal vascularity, so-called hot spot. Other techniques have been developed such as Chalkley counting and the use of image analysis systems that are robust and reproducible as well as being more objective. Many of the molecular pathways that govern tumor neovascularization have been identified and many reagents are now available to study these tissue sections. These include angiogenic growth factors and their receptors and cell adhesion molecules, proteases, and markers of activated, proliferating, cytokine-stimulated, or angiogenic vessels, such as CD105. It is also possible to differentiate quiescent from active vessels. Other reagents that can identify proteins involved in microenvironmental influences such as hypoxia have also been generated. Although the histological assessment of tumor vascularity is used mostly in the research context, it may also have clinical applications if appropriate methodology and trained observers perform the studies.

Thymidine Phosphorylase in Cancer; Enemy or Friend?

Thymidine phosphorylase (TP) is a nucleoside metabolism enzyme that plays an important role in the pyrimidine pathway.TP catalyzes the conversion of thymidine to thymine and 2-deoxy-α-D-ribose-1-phosphate (dRib-1-P). Although this reaction is reversible, the main metabolic function of TP is catabolic. TP is identical to the angiogenic factor platelet-derived endothelial-cell growth factor (PD-ECGF). TP is overexpressed in several human cancers in response to cellular stressful conditions like hypoxia, acidosis, chemotherapy and radiotherapy. TP has been shown to promote tumor angiogenesis, invasion, metastasis, evasion of the immune-response and resistance to apoptosis. Some of the biological effects of TP are dependent on its enzymatic activity, while others are mediated through cytokines like interleukin 10 (IL-10), basic fibroblast growth factor (bFGF) and tumour necrosis factor α (TNFα). Interestingly, TP also plays a role in cancer treatment through its role in the conversion of the oral fluoropyrimidine capecitabine into its active form 5-FU. TP is a predictive marker for fluoropyrimidine response. Given its various biological functions in cancer progression, TP is a promising target in cancer treatment. Further translational research is required in this area.

5-Fluorouracil pharmacogenomics: still rocking after all these years?

The 5-fluorouracil (5-FU) metabolic pathway is mainly dependent on the activity of several intracellular enzymes. Among them, four in particular; thymidylate synthase, methylenetetrahydrofolate reductase, dihydropyrimidine dehydrogenase and thymidine phosphorylase are considered the key points in determining sensitivity or resistance to this drug. These enzymes are needed to metabolize the drug in its active form (thymidylate phosphorylase) or to drop the concentration of the active drug in the cell (dihydropyrimidine dehydrogenase) or both (thymidylate synthase and methylenetetrahydrofolate reductase). Several different studies have tried to investigate the relationship between the presence of mutations in these enzymes and a reduced/improved activity of treatment based on 5-FU or its derivatives. In this article, we will focus on the often contradictory results of these studies.

The dual role of thymidine phosphorylase in cancer development and chemotherapy

Thymidine phosphorylase (TP), also known as "platelet-derived endothelial cell growth factor" (PD-ECGF), is an enzyme, which is upregulated in a wide variety of solid tumors including breast and colorectal cancers. TP promotes tumor growth and metastasis by preventing apoptosis and inducing angiogenesis. Elevated levels of TP are associated with tumor aggressiveness and poor prognosis. Therefore, TP inhibitors are synthesized in an attempt to prevent tumor angiogenesis and metastasis. TP is also indispensable for the activation of the extensively used 5-fluorouracil prodrug capecitabine, which is clinically used for the treatment of colon and breast cancer. Clinical trials that combine capecitabine with TP-inducing therapies (such as taxanes or radiotherapy) suggest that increasing TP expression is an adequate strategy to enhance the antitumoral efficacy of capecitabine. Thus, TP plays a dual role in cancer development and therapy: on the one hand, TP inhibitors can abrogate the tumorigenic and metastatic properties of TP; on the other, TP activity is necessary for the activation of several chemotherapeutic drugs. This duality illustrates the complexity of the role of TP in tumor progression and in the clinical response to fluoropyrimidine-based chemotherapy.

Sequential administration of dose-dense epirubicin/cyclophosphamide followed by docetaxel/capecitabine for patients with HER2-negative and locally advanced or node-positive breast cancer

PURPOSE

Capecitabine is effective against metastatic breast cancer (MBC). We hypothesized that sequential treatment with dose-dense epirubicin/cyclophosphamide (EC) and docetaxel/capecitabine would be active and tolerable in the adjuvant/neoadjuvant setting.

METHODS

In this prospective phase II clinical trial patients with HER2-negative and node-positive or locally advanced tumors were eligible to receive four cycles of EC (100/600 mg/m2) every 2 weeks with G-CSF on days 3-10, followed by four cycles of docetaxel/capecitabine (75/1,000 mg/m2 b.i.d., days 1-14) every 3 weeks.

RESULTS

Fifty-five patients were enrolled with median age of 49, and 80% had hormone receptor-positive disease. The median tumor size was 2.5 cm, with a median of two axillary nodes involved. Seventy-five percent of the first 20 patients had grade 2/3 hand-foot syndrome (HFS). Dose reduction of capecitabine to 800 mg/m2 reduced the grade 2/3 HFS incidence to 31% in the remaining patients. No grade 4/5 toxicities were observed. All 20 patients treated preoperatively responded, with 5 (25%) pathologic complete responses and 3 additional pT0N1 tumors. At a median follow-up of 48 (range 28-60) months, the event-free and overall survival rates are 91 and 98%, respectively.

CONCLUSIONS

Sequential treatment with dose-dense EC followed by docetaxel/capecitabine, using a lower capecitabine dose than that approved for MBC, has an acceptable toxicity profile and encouraging activity when used as neoadjuvant or adjuvant treatment of breast cancer.

Assessing tumor angiogenesis in histological samples

Tumor neovascularization acquires vessels through a number of processes, including angiogenesis, vasculogenesis, vascular remodelling, intussusception, and possibly vascular mimicry in certain tumors. The end result of the tumor vasculature has been quantified by counting the number of immunohistochemically identified microvessels in areas of maximal vascularity so-called hot spots. Other techniques have been developed, such as Chalkley counting and the use of image analysis systems that are robust and reproducible as well as more objective. Many of the molecular pathways that govern tumor neovascularization have been identified, and many reagents are now available to study these tissue sections. These include angiogenic growth factors and their receptors, cell adhesion molecules, proteases, and markers of activated, proliferating, cytokine-stimulated, or angiogenic vessels, such as CD105. It is also possible to differentiate quiescent from active vessels. Other reagents that can identify proteins involved in microenvironmental influences such as hypoxia have also been generated. Although the histological assessment of tumor vascularity is used mostly in the research context, it may also have clinical applications if appropriate methodology and trained observers perform the studies.

Breast tumour angiogenesis

The central importance of tumour neovascularization has been emphasized by clinical trials using antiangiogenic therapy in breast cancer. This review gives a background to breast tumour neovascularization in in situ and invasive breast cancer, outlines the mechanisms by which this is achieved and discusses the influence of the microenvironment, focusing on hypoxia. The regulation of angiogenesis and the antivascular agents that are used in an antiangiogenic dosing schedule, both novel and conventional, are also summarized.

The angiogenic factor thymidine phosphorylase up-regulates the cell adhesion molecule P-selectin in human vascular endothelial cells and is associated with P-selectin expression in breast cancers

Thymidine phosphorylase (TP) is an angiogenic enzyme, catalysing the reversible phosphorylation of thymidine to thymine and 2-deoxyribose. TP is up-regulated in neoplasia, being associated with advanced tumour stage, microvessel density and prognosis in several tumour types. Although TP is a non-mitogenic migratory factor for endothelium, the mechanism by which TP mediates these effects is still unclear. We compared the gene expression profile of endothelial cells grown in vitro in the presence or absence of TP by cDNA microarray analysis. To determine the time-course of TP angiogenic induction, endothelial cells were stimulated with TP (10 ng/ml) for 5 and 18 h. Gene expression levels of Tie2, angiopoietin (Ang)1 and Ang2, measured by RNase protection assay (RPA), showed maximal alteration at 18 h. cDNA from human umbilical vein endothelial cells (HUVEC) grown for 18 h in the presence or absence of TP (10 ng/ml) was hybridized to a human cDNA cytokine array representing 375 angiogenic genes. Significantly altered expression occurred in 89 human angiogenic genes (72 genes were up-regulated and 17 down-regulated). Changes in five genes relevant to vascular remodelling biology (Tie2, nNos, P-selectin, ephrin-B1 and TP) were validated in triplicate experiments by real-time RT-PCR. But only P-selectin gene expression remained significant. Correlation between P-selectin and TP was assessed by immunohistochemistry on 161 human breast cancers, using human tissue microarray. Tumour cell TP correlated with tumour cell P-selectin but not with endothelial cell P-selectin. These data show that TP stimulates changes in mRNA expression maximally after 18 h culture in vitro. It confirms a role for TP in vascular remodelling involving several classes of genes, including the cell adhesion molecule, P-selectin. Although confirmation of the role of TP-mediated cell adhesion molecule (CAM) induction is required; however, this pathway may provide an attractive therapeutic target, since it is likely to affect several important tumour processes, including angiogenesis and metastasis.

Expression of the High-Affinity Fluoropyrimidine-Preferring Nucleoside Transporter hCNT1 Correlates with Decreased Disease-Free Survival in Breast Cancer

PURPOSE

Nucleoside and nucleobase derivatives are currently used in the treatment of a variety of solid tumors; however, the role of plasma membrane transporters as biomarkers of drug metabolism has not been fully addressed. Thus, the purpose of this study was to determine whether the concentrative nucleoside transporter hCNT1 is a predictive marker of therapeutic response.

METHODS

We studied a cohort of 90 breast cancer patients who were treated with cyclophosphamide-methotrexate-5-fluorouracil after surgery and then monitored for up to 108 months. hCNT1 and enzymes associated with nucleotide metabolism (thymidine phosphorylase, dihydropyrimidine dehydrogenase and thymidylate synthase) were assessed immunohistochemically in tissue samples.

RESULTS

Human CNT1 presence was mostly cytoplasmic, with some nuclear staining. The percentage of hCNT1-positive cells correlated positively with the expression of thymidine phosphorylase and dihydropyrimidine dehydrogenase. Nuclear staining correlated negatively with decreased disease-free survival, whereas the percentage of hCNT1-positive cells correlated positively with reduced long-term survival, with the hCNT1-positive index (>80%) being indicative of poor prognosis. A relative risk of relapse was associated with high hCNT1-positive indexes, whereas when this parameter was combined with the nodal status (positive), a high risk of relapse was found, suggesting that both parameters may reflect a poor prognosis.

CONCLUSIONS

These results indicate that the expression of the high-affinity concentrative nucleoside transporter hCNT1 has a prognostic value in determining disease-free survival and risk of relapse in breast cancer patients undergoing surgery followed by cyclophosphamide-methotrexate-5-fluorouracil chemotherapy.

An evaluation of thymidine phosphorylase as a means of preventing thymidine rescue from the thymidylate synthase inhibitor raltitrexed

The antitumour effect of thymidylate synthase inhibitors such as raltitrexed (RTX) may be reversed by salvage of thymidine (Thd). Since thymidine phosphorylase (TP) depletes Thd, the potential for tumour-selective depletion of Thd using antibody-mediated delivery of TP to tumours was investigated. In vitro studies demonstrated that 25 x 10(-3) units/ml TP depleted extracellular Thd (3 microM) and restored sensitivity to the growth inhibitory effects of RTX in Lovo and HT29 cell lines. Thymidine concentrations in xenograft tumours were inversely proportional to the activity of TP in the tumour, and the presence of a subcutaneous Lovo xenograft reduced plasma Thd concentrations from 0.92 +/- 0.07 to 0.37 +/- 0.04 microM. Intravenous administration of native TP enzyme depleted plasma Thd to 5 nM, but following rapid elimination of TP, plasma Thd returned to pretreatment values. There was no effect on tumour TP or Thd. Conjugation of TP to the A5B7 F(ab)2 antibody fragment, which targets carcinoembryonic antigen (CEA) expressed on colorectal cell-lines such as Lovo, did result in selective accumulation of TP in the tumour. However, there was no tumour-selective depletion of Thd and there did not appear to be any potential benefit of combining antibody-targeted TP with RTX.

Genetic factors influencing pyrimidine-antagonist chemotherapy

Pyrimidine antagonists, for example, 5-fluorouracil (5-FU), cytarabine (ara-C) and gemcitabine (dFdC), are widely used in chemotherapy regimes for colorectal, breast, head and neck, non-small-cell lung cancer, pancreatic cancer and leukaemias. Extensive metabolism is a prerequisite for conversion of these pyrimidine prodrugs into active compounds. Interindividual variation in the activity of metabolising enzymes can affect the extent of prodrug activation and, as a result, act on the efficacy of chemotherapy treatment. Genetic factors at least partly explain interindividual variation in antitumour efficacy and toxicity of pyrimidine antagonists. In this review, proteins relevant for the efficacy and toxicity of pyrimidine antagonists will be summarised. In addition, the role of germline polymorphisms, tumour-specific somatic mutations and protein expression levels in the metabolic pathways and clinical pharmacology of these drugs are described. Germline polymorphisms of uridine monophosphate kinase (UMPK), orotate phosphoribosyl transferase (OPRT), thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD) and methylene tetrahydrofolate reductase (MTHFR) and gene expression levels of OPRT, UMPK, TS, DPD, uridine phosphorylase, uridine kinase, thymidine phosphorylase, thymidine kinase, deoxyuridine triphosphate nucleotide hydrolase are discussed in relation to 5-FU efficacy. Cytidine deaminase (CDD) and 5'-nucleotidase (5NT) gene polymorphisms and CDD, 5NT, deoxycytidine kinase and MRP5 gene expression levels and their potential relation to dFdC and ara-C cytotoxicity are reviewed.

Facts and Controversies in Systemic Treatment of Metastatic Breast Cancer

The management of metastatic breast cancer remains an important and controversial issue. The systemic therapy, comprising endocrine, cytotoxic and biological agents, can be administered sequentially or in combination. Few drugs or combinations provide a significant improvement in survival and, therefore, in the great majority of cases, treatment is given with a palliative intent. With the exception of first-line therapy, for which general agreement exists, currently there is no consensual standard of care. This review will summarize the current knowledge and outline the controversial issues related to systemic therapy of metastatic breast cancer, with emphasis on treatment tailoring. The potential role of tumor molecular profile(s) in the selection of patients that could benefit the most from each strategy/agent will be discussed.

Modulation of thymidine phosphorylase by neoadjuvant chemotherapy in primary breast cancer

The combination effect of docetaxel and capecitabine on tumour response rate and survival was demonstrated recently in metastatic breast cancer patients. This combination was based on an experimental hypothesis that taxane can increase tumour sensitivity to the effect of capecitabine through the upregulation of thymidine phosphorylase (TP), which is responsible for the metabolism of 5-fluorouracil (5-FU) and its derivatives, including capecitabine. To examine the alteration in TP expression before and after neoadjuvant chemotherapy, 92 patients with primary breast cancer (T2-4N0-1M0) were enrolled in this study; 14 were treated with adriamycin and cyclophosphamide (AC) or epirubicin and cyclophosphamide (EC); 58 with 5-FU, adriamycin, and cyclophosphamide (FAC) or 5-FU, epirubicin, and cyclophosphamide (FEC); and 20 with FEC followed by docetaxel/taxotere (TXT-containing regimen). Thymidine phosphorylase upregulation was seen in 54.4% and 32.6% of patients in tumour cells and stromal cells, respectively. Increases in TP expression were found only in the AC/EC and TXT-containing regimen groups. In conclusion, it was strongly suggested that unlike 5-FU-containing regimens, the taxane and AC combination therapies upregulate TP expression in primary breast cancer. Thymidine phosphorylase upregulation by several anticancer drugs implies the importance of individualised strategies for sensitisation of tumour tissues to 5-FU and its derivatives.

The effect of fluoropyrimidines with or without thymidine phosphorylase inhibitor on the expression of thymidine phosphorylase

Thymidine phosphorylase (platelet-derived-endothelial-cell-growth-factor) catalyzes the reversible phosphorolysis of thymidine to thymine and 2-deoxyribose-1-phosphate, activates 5'-deoxy-5-fluorouridine (5'DFUR) and inactivates trifluorothymidine (TFT). The effect of 5'DFUR and TFT with or without a specific thymidine phosphorylase inhibitor (TPI) on thymidine phosphorylase mRNA, protein expression and activity was studied, in three human colon cancer cell lines, WiDR, HT29 and Lovo exposed for 72 h at IC50 concentrations. In Lovo cells TFT plus TPI only increased thymidine phosphorylase-protein expression 1.7-fold; 5'DFUR and TFT treatment increased thymidine phosphorylase mRNA levels 5- and 1.4-fold, respectively. In WiDR cells, 5'DFUR plus TPI significantly decreased thymidine phosphorylase-protein. TFT and TFT plus TPI increased thymidine phosphorylase-protein 2- and 3-fold, respectively. TPI and 5'DFUR decreased thymidine phosphorylase-mRNA levels significantly. In HT29 cells, 5'DFUR and 5'DFUR plus TPI decreased both thymidine phosphorylase-protein and thymidine phosphorylase-mRNA. In all cell lines 5'DFUR and TFT did not affect thymidine phosphorylase activity, but treatment with TPI (alone or in combination) eliminated thymidine phosphorylase activity. This demonstrated that regulation is drug and cell line dependent.

A phase II study of weekly docetaxel plus capecitabine for patients with advanced nonsmall cell lung carcinoma

BACKGROUND

Docetaxel is an active agent in advanced nonsmall-cell lung carcinoma (NSCLC) and demonstrates preclinical and clinical synergism with capecitabine. We conducted the current Phase II study to evaluate the efficacy and safety of the docetaxel/capecitabine combination in chemotherapy-naive patients with advanced NSCLC.

METHODS

Eligibility required Stage IIIB or IV NSCLC, bidimensionally measurable disease, and an Eastern Cooperative Oncology Group performance score of 2 or lower. Treatment consisted of docetaxel 36 mg/m(2) intravenously on Days 1 and 8 plus capecitabine 1000 mg/m(2) orally twice per day on Days 1-14 of a 21-day cycle, for a maximum of 6 cycles.

RESULTS

Of 39 patients enrolled, 39 and 36 patients were evaluated for toxicity and response, respectively. The overall response rate was 53% (95% confidence interval [CI], 37-69%) with 19 partial responses (no complete response). The median duration of response was 6.2 months (range, 2.1-15.7 months). At a median follow-up of 14.2 months, 19 patients died. The median overall survival time was 17.8 months, with a 1-year survival rate of 56.4% (95% CI, 40.9-72.0%). There were two treatment-related deaths (one death due to pneumonia and one due to sepsis). Hematologic toxicity was mild to moderate. Thirteen percent of the patients had Grade 3 or 4 neutropenia. However, Grade 2 or 3 nonhematologic toxicities were frequent, which included asthenia (51%), stomatitis (33%), hand-foot syndrome (33%), and diarrhea (29%).

CONCLUSIONS

The docetaxel/capecitabine combination showed promising antitumor activity for chemotherapy-naive patients with advanced NSCLC, However, it was frequently associated with moderate-to-severe nonhematologic toxicities, suggesting clinical synergism in both efficacy and toxicity. Further adjustment of the dose schedule is recommended to maximize the therapeutic index.

Pd-ECGF positivity correlates with better survival, while iNOS has no predictive value for cervical carcinomas treated with radiotherapy

PURPOSE

Platelet-derived endothelial cell growth factor (PD-ECGF), which has angiogenic activity, is identical to thymidine phosphorylase. Tumor vascularization is considered to be an important prognostic factor. Nitric oxide synthases (NOSs) are a kind of enzyme that generates nitric oxide. Nitric oxide has not only a self defense against neoplastic cells but also tumor growth stimulation by promoting new blood vessel formation. Our purpose was to investigate the correlation between the expression of PD-ECGF or inducible NOS (iNOS) in cancer cells and prognosis.

METHODS AND MATERIALS

Formaldehyde-fixed and paraffin-embedded biopsy specimens excised from 71 cervical squamous cell carcinoma patients who were treated with radiotherapy alone were investigated using an immunohistochemical method.

RESULTS

Cancer cells that were positive for PD-ECGF showed intranuclear and cytoplasmic staining patterns. Of the 71 patients, 40 (56%) were positive for PD-ECGF and 31 (44%) were negative. The 5-year survival of the PD-ECGF-positive patients was significantly better than that of the PD-ECGF-negative patients (p = 0.026). Cancer cells that were positive for iNOS showed a cytoplasmic staining pattern. Twenty-seven patients (38%) were positive for iNOS and 44 (62%) were negative. No significant prognostic correlation was observed between iNOS-positive and iNOS-negative patients.

CONCLUSION

PD-ECGF positivity in cancer cells is a predictive factor for a good prognosis in cervical squamous cell carcinoma treated with radiotherapy alone.

Role of platelet-derived endothelial cell growth factor/thymidine phosphorylase in fluoropyrimidine sensitivity

Platelet-derived endothelial cell growth factor (PD-ECGF)/thymidine phosphorylase (TP) catalyses the reversible phosphorolysis of thymidine to thymine and 2-deoxyribose-1-phosphate and is involved in the metabolism of fluoropyrimidines. It can also activate 5'-deoxyfluorouridine (5'DFUR) and possibly 5-fluorouracil (5FU) and Ftorafur (Ft), but inactivates trifluorothymidine (TFT). We studied the contribution of TP activity to the sensitivity for these fluoropyrimidines by modulating its activity and/or expression level in colon and lung cancer cells using a specific inhibitor of TP (TPI) or by overproduction of TP via stable transfection of human TP. Expression was analysed using competitive template-RT-PCR (CT-RT-PCR), Western blot and an activity assay. TP activity ranged from nondetectable to 70678 pmol h(-1) 10(-6) cells, in Colo320 and a TP overexpressing clone Colo320TP1, respectively. We found a good correlation between TP activity and mRNA expression (r=0.964, P&<0.01) in our cell panel. To determine the role of TP in the sensitivity to 5FU, 5'DFUR, Ft and TFT, cells were cultured with the various fluoropyrimidines with or without TPI and differences in IC(50)'s were established. TPI modified 5'DFUR, increasing the IC(50)'s 2.5- to 1396-fold in WiDR and Colo320TP1, respectively. 5-Fluorouracil could be modified by inhibiting TP but to a lesser extent than 5'DFUR: IC(50)'s increased 1.9- to 14.7-fold for WiDR and Colo320TP1, respectively. There was no effect on TFT or Ft. There appears to be a threshold level of TP activity to influence the 5'DFUR and 5FU sensitivity, which is higher for 5FU. Even high levels of TP overexpression only had a moderate effect on 5FU sensitivity.

Expression of thymidylate synthase and thymidine phosphorylase in human breast carcinoma: implication for method to detect expression of these molecules in clinic

Thymidine phosphorylase (dThdPase) is identical to platelet-derived endothelial cell growth factor, and has an angiogenic activity in experimental models and human solid tumors. A critical step in the de novo pathway of DNA synthesis is the production of the pyrimidine nucleotide dTMP from dump and this reaction is catalyzed by thymidylate synthase (TS). Both dThdPase and TS levels seemed to be related to response to 5-fluorouracil (5-FU) therapy in different types of human solid tumors. The present study evaluated dThdPase and TS expression levels by immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR), using a same set of 39 breast carcinoma tissues for both methods. An inverted-relationship in the expression levels of TS and dThdPase was observed. Further, immunohistochemical analysis may be a better tool than analysis by RT-PCR in detection of dThdPase and TS, because of both dThdPase and TS expression in cells besides carcinoma cells. These imply that immunohistochemical analysis of dThdPase and TS is available for selection of patients who will be received 5-FU based chemotherapy.

Thymidine phosphorylase is regulated by tamoxifen in T47D breast cancer cell line

BACKGROUND

Thymidine phosphorylase (TP) has diverse functions within cells, including increasing the sensitivity of cancer cells to cytotoxic drugs including 5-fluorouracil (5-FU) and methotrexate. However, the regulators of TP still remains largely unknown.

METHOD

In this study, we examined whether tamoxifen has specific effects on TP expression in the T47D breast cancer cell line. We studied the TP expression in the T47D cell line before and after tamoxifen treatment using Western blot analysis and ELISA.

RESULTS

We found that TP expression is significantly up-regulated in tamoxifen-treated cells compared with control.

CONCLUSIONS

Our findings suggest that tamoxifen may increase chemotherapy sensitivity through TP up-regulation for treatment regimens including doxifluridine, capecitabine, and/or methotrexate.

Intra-tumoural microvessel density in human solid tumours

Over the last decade assessment of angiogenesis has emerged as a potentially useful biological prognostic and predictive factor in human solid tumours. With the development of highly specific endothelial markers that can be assessed in histological archival specimens, several quantitative studies have been performed in various solid tumours. The majority of published studies have shown a positive correlation between intra-tumoural microvessel density, a measure of tumour angiogenesis, and prognosis in solid tumours. A minority of studies have not demonstrated an association and this may be attributed to significant differences in the methodologies employed for sample selection, immunostaining techniques, vessel counting and statistical analysis, although a number of biological differences may account for the discrepancy. In this review we evaluate the quantification of angiogenesis by immunohistochemistry, the relationship between tumour vascularity and metastasis, and the clinicopathological studies correlating intra-tumoral microvessel density with prognosis and response to anti-cancer therapy. In view of the extensive nature of this retrospective body of data, comparative studies are needed to identify the optimum technique and endothelial antigens (activated or pan-endothelial antigens) but subsequently prospective studies that allocate treatment on the basis of microvessel density are required.

Prognostic and predictive value of thymidine phosphorylase activity in early-stage breast cancer patients

The antitumor effects of 5-fluorouracil (5-FU) and its derivatives depend upon the activity of nucleoside metabolic enzymes in tumor tissues. Thymidine phosphorylase (TP) converts 5'-deoxy-5-fluorouridine (5'-DFUR), an intermediate metabolite of capecitabine, to 5-FU. The relationship between TP expression in tumor tissues and patient survival was retrospectively examined in early-stage breast cancer patients treated with either oral 5'-DFUR administered for 6 months or surgery alone in a prospective randomized controlled trial. Thymidine phosphorylase expression in tumor cells and tumor-associated stromal (TAS) cells was examined by immunohistochemistry in 650 tissue samples from patients in this trial (n = 1217). Eight-year follow-up data showed that high TP expression in tumor cells was a significant prognostic indicator of a favorable outcome only for the patients in the 5'-DFUR group. Thus, TP expression was shown to be a predictive factor of 5'-DFUR efficacy. Conversely, a low TP expression in TAS cells was also a potent favorable prognostic indicator. These results on TP status in 2 tumor cell types could provide novel information for predicting prognosis for a patient subgroup, which would receive a probable therapeutic effect from 5'-DFUR, and presumably, from adjuvant therapy of capecitabine in early-stage breast cancer. Determination of TP status might also identify a patient subgroup whose prognosis is quite favorable even without adjuvant therapy. Further investigations on prognostic and predictive implications of TP activity in a clinical setting are warranted.

Predictive and prognostic markers for invasive breast cancer

Breast cancer is one of the most serious carcinomas among women worldwide, yet there are now encouraging signs that improvements in the mortality rate may be possible. The use of hormone therapy and chemotherapy has been widely accepted as treatment for breast cancer. Predictive factors can be used to predict response or lack of response to a particular therapy, and prognostic factors can be useful in making decisions about which patients should receive adjuvant therapy. Histopathology remains the universal basis of diagnosis, with the identification of new surrogate markers for potential new treatments. These are aimed at blocking tumor cell proliferation, neutralizing growth factors, stimulating apoptosis and blocking metastasis, and represent an integral part of new approaches for improving clinical management of patients with breast cancer. We review the standard predictive and prognostic factors that are routinely available today, and also describe some of the new, potential markers that are currently under investigation.

Prognostic value of thymidine phosphorylase expression in breast carcinoma

Thymidine phosphorylase (TP), also known as platelet-derived endothelial cell growth factor (PD-ECGF), is an enzyme that catalyzes the reversible dephosphorylation of thymidine, deoxyuridine and their analogs. TP has also angiogenic properties, although the precise mechanism by which it promotes angiogenesis is not known. We examined TP expression using immunohistochemistry (654-1 Mab) in 182 invasive breast carcinomas (67 N0 and 115 N1/2; median follow-up 78 months [range, 3-177]; 51 patients treated with adjuvant systemic cyclophosphamide, methotrexate and 5-fluorouracil [CMF] chemotherapy and 82 with tamoxifen). High TP expression was found in 142 cases (78%) and correlated with lower histologic grade and low p53 expression. No correlation was found between TP expression and vascular density. TP-positive tumors had a significant increase in both disease-free survival (DFS; p = 0.0025) and overall survival (OS; p = 0.0070) in the total cohort of patients and in the subgroups of node-positive patients and patients treated with CMF adjuvant therapy; no significant difference in either DFS or OS was observed in patients without CMF treatment. Our findings suggest that TP has little effect on tumor angiogenesis of breast carcinoma, whereas it could represent an interesting marker that could predict response to CMF chemotherapy.

Plasminogen activator inhibitor-1 as a measure of vascular remodelling in breast cancer

The generation of urokinase plasminogen activator (uPA) by tumours is an important pathway for neoplastic cell invasion and metastasis. Indeed in several tumour types, elevated levels of uPA, its receptor (uPAR) or its inhibitor plasminogen activator inhibitor-1 (PAI-1) is associated with a poorer prognosis. Since endothelial cells also use this proteolytic system to remodel the extracellular matrix during angiogenesis and since angiogenesis, as assessed by microvessel density, is also a predictor of patient survival, this study was designed to investigate the relationship between angiogenesis and the urokinase system in breast tumours. The aims were to assess whether the uPA, uPAR and/or PAI-1 correlates with angiogenic activity and could therefore be a useful objective clinical measure of tumour neovascularization; and to clarify whether the poor outcome associated with high levels of the urokinase system is due to its association with angiogenesis. The study also sought to examine the relationship between the uPA system and vessel remodelling using loss of a basement membrane epitope (LH39) normally associated with established capillaries. The cytosolic levels of uPA, PAI-1 and uPAR were therefore measured by enzyme linked immunoabsorbent assay, together with tumour vascularity, in 136 well-characterized invasive breast carcinomas. There were significant relationships between uPA and uPAR (Spearman r=0.37, p<0.0001), uPA and PAI-1 (Spearman r=0.19, p=0.03) and between uPAR and PAI-1 (Spearman r=0.23 p=0.01). A significant correlation was also observed between PAI-1 and vessel remodelling (Spearman r=0.34, p=0.04), patient age (p=0.01), nodal status (p=0.047) and tumour grade (p=0.04), but no association between tumour vascularity and PAI (p=0.96), uPA (p=0.69) or uPAR (p=0.81) was present. No significant association was seen between any of the urokinase variables and expression of the angiogenic factor thymidine phosphorylase. Furthermore, no significant associations were found between any of the studied parameters and overall survival in a univariate analysis of the cancer patients. A multivariate Cox proportional hazard model of overall survival showed that uPA (p=0.15), but not uPAR (p=0.52) or PAI-1 (p=0.61), gave no additional prognostic information. These findings show that uPA may work via an independent pathway to angiogenesis and therefore combined blockade of uPA and angiogenesis may have additional therapeutic benefits. It also shows, as recently demonstrated in animal models, that PAI-1 may be a key regulator of vascular remodelling in human cancer.

The predictive value of angiogenesis for adjuvant therapy in breast cancer

Recent accumulated data have indicated that angiogenesis is a promising indicator to predict prognosis and response to treatment. In breast cancer, microvessel density (MVD), a semi-quantitative marker of neovascularization grade, has been suggested to provide independent prognostic value. In addition, the expression of both vascular endothelial growth factor (VEGF)and thymidine phosphorylase (TP), two angiogenesis regulatory molecules, were found to be closely associated with MVD, and with the effect of treatments. In particular, VEGF expression seems to be a phenotype resistant to endocrine therapy, whereas TP expression decreases sensitivity to chemotherapy containing fluorouracil. This review summarizes the current topics regarding the prognostic and predictive value of angiogenesis in primary breast cancer, and we discuss future applications of antiangiogenesis treatments in an adjuvant setting.

VEGF-B expression in human primary breast cancers is associated with lymph node metastasis but not angiogenesis

Angiogenesis is essential for tumour growth and metastasis. It is regulated by numerous angiogenic factors, one of the most important being vascular endothelial growth factor (VEGF). Recently VEGF-B, a new VEGF family member that binds to the tyrosine kinase receptor flt-1, has been identified. Although the importance of VEGF has been shown in many human tumour types, the contribution of VEGF-B to tumour neovascularization is unknown in any tumour type. This study therefore measured the mRNA level of VEGF-B and its receptor flt-1 by ribonuclease protection assay and the pattern of VEGF-B expression by immunohistochemistry in 13 normal breast samples and 68 invasive breast cancers. Flt-1 expression was significantly higher in tumours than in normal breast (p=0.02) but no significant difference was seen in VEGF-B between normal and neoplastic breast (p=0.3). There was a significant association between VEGF-B and node status (p=0.02) and the number of involved nodes (p=0.01), but not with age (p=0.7), size (p=0.6), oestrogen receptor (ER) (p=0.2), grade (p=0.5) or vascular invasion (p=0.16). No significant relationship was present between VEGF-B and flt-1 (p=0.2) or tumour vascularity (p=0.4). VEGF-B was expressed mostly in the cytoplasm of tumour cells, although occasional stromal components including fibroblasts and endothelial cells were also positive. No difference in VEGF-B expression was observed adjacent to regions of necrosis, in keeping with this VEGF family member not being hypoxically regulated. These findings suggest that VEGF-B may contribute to tumour progression by a non-angiogenic mechanism, possibly by increasing plasminogen activators and hence metastasis, as has been described in vitro. Measurement of VEGF-B together with other angiogenic factors may identify a poor prognostic patient group, which may benefit from anti-VEGF receptor therapy targeted to flt-1 (VEGFR1) as well as kdr (VEGFR2).

Clinical significance of determination of surrogate markers of angiogenesis in breast cancer

Compelling experimental and clinical data support the concept that breast carcinoma, as most of the other solid tumors, needs to develop the angiogenic phenotype for invasiveness, progression and metastasis. Several studies have determined intratumoral microvessel density by panendothelial markers and immunohistochemical techniques, with most of them showing that the degree of vascularity is associated with prognosis of the patients operated of early-stage invasive breast cancer. More recently, certain angiogenic peptides have been assessed in human breast cancer: vascular endothelial growth factor (VEGF), platelet derived-endothelial cell growth factor (PD-ECGF, also known as thymidine phosphorylase, TP) and fibroblast growth factor family (FGFs). Among these, the most studied is VEGF, which appears to be a powerful prognostic indicator. Little data are available on the clinical significance of naturally occurring antiangiogenic factors, with few studies reporting on interleukin-12 and thrombospondins. In vivo techniques for dynamic assessment of tumor blood network are presently under extensive research, in particular for monitoring activity of inhibitors of angiogenesis. The methods of assessment of angiogenic activity and the results of published clinical studies in peer reviewed Journals with a computerized overview of literature will be presented. Overall, the results of the reported studies suggest that human breast cancer is an angiogenic-dependent tumor for which antiangiogenic therapy represents a promising novel antitumoral therapeutic strategy.

Vascular endothelial growth factor, platelet-derived endothelial cell growth factor and angiogenesis in non-small-cell lung cancer

High microvessel density, an indirect measure of angiogenesis, has been shown to correlate with increased tumour size, lymph node involvement and poor prognosis in non-small-cell lung cancer (NSCLC). Tumour cell vascular endothelial growth factor (VEGF) and platelet-derived endothelial cell growth factor (PD-ECGF) expression correlate with angiogenesis and a poor outcome in this disease. In a retrospective study VEGF and PD-ECGF expression and microvessel density were evaluated immunohistochemically in surgically resected specimens (T1-3, N0-2) from 223 patients with operable NSCLC using the VG1, P-GF.44C and JC70 monoclonal antibodies respectively. High VEGF immunoreactivity was seen in 104 (46.6%) and PD-ECGF in 72 (32.3%) cases and both were associated with high vascular grade tumours (P= 0.009 and P= 0.05 respectively). Linear regression analysis revealed a weak positive correlation between VEGF and PD-ECGF expression in cancer cells (r= 0.21; P = 0.002). Co-expression of VEGF and PD-ECGF was not associated with a higher microvessel density than VEGF or PD-ECGF only expressing tumours. Furthermore a proportion of high vascular grade tumours expressed neither growth factor. Univariate analysis revealed tumour size, nodal status, microvessel density and VEGF and PD-ECGF expression as significant prognostic factors. Tumour size (P < 0.02) and microvessel density (P < 0.04) remained significant on multivariate analysis. In conclusion, VEGF and PD-ECGF are important angiogenic growth factors and have prognostic significance in NSCLC. Furthermore the study underlines the prognostic significance of microvessel density in operable NSCLC.

Increased cytotoxicity and bystander effect of 5-fluorouracil and 5-deoxy-5-fluorouridine in human colorectal cancer cells transfected with thymidine phosphorylase

5-Fluorouracil (5-FU) and 5'-deoxy-5-fluorouridine (5'-DFUR), a prodrug of 5-FU, are anticancer agents activated by thymidine phosphorylase (TP). Transfecting the human TP cDNA into cancer cells in order to sensitize them to these pyrimidine antimetabolites may be an important approach in human cancer gene therapy research. In this study, an expression vector containing the human TP cDNA (pcTP5) was transfected into LS174T human colon carcinoma cells. Eight stable transfectants were randomly selected and analysed. The cytotoxic effects of 5-FU and 5'-DFUR were higher in TP-transfected cells as compared to wild-type cells. The maximal decreases in the IC50 were 80-fold for 5-FU and 40-fold for 5'-DFUR. The increase in sensitivity to these pyrimidines of TP-transfected cells significantly correlated with the increase in both TP activity and TP expression. Transfected clone LS174T-c2 but not wild-type cells exhibited formation of [3H]FdUMP from [3H]5-FU. In addition the LS174T-c2 clone enhanced the cytotoxic effect of 5'-DFUR, but also that of 5-FU, towards co-cultured parental cells. For both anti-cancer agents, this bystander effect did not require cell-cell contact. These results show that both 5-FU or 5'-DFUR could be used together with a TP-suicide vector in cancer gene therapy.

Thymidine phosphorylase: its role in sensitivity and resistance to anticancer drugs

Thymidine phosphorylase (TP) is an angiogenic enzyme present in normal tissues. Increased levels are found in many tumors, in stromal cells, tumor cells or both. High tumor TP levels may confer a poor prognosis. Cytokines (including interferons), tissue hypoxia and low pH increase TP levels. The influence of tumor TP on fluoropyrimidine toxicity is variable, but capecitabine is a prodrug of fluorouracil that requires activation by TP and hence may have a higher therapeutic index than other fluoropyrimidines. Folate-based thymidylate synthase inhibitors may also be more effective in tumors with a high TP because of increased degradation of endogenous thymidine. Copyright 1999 Harcourt Publishers Ltd.

Thymidine phosphorylase expression in endometrial carcinomas

Thymidine phosphorylase (TP) is a potent angiogenic molecule shown to induce endothelial cell migration and proliferation. We investigated the expression of TP in a series of 156 endometrial carcinomas, using immunohistochemical methods. Histopathological parameters of known prognostic significance and the molecular factors of p53, bcl-2 and angiogenesis were also assessed. Thymidine phosphorylase was expressed in cancer cells, stromal fibroblasts and myometrial cells. The pattern of TP staining was nuclear or mixed nuclear/cytoplasmic, and only exceptionally was purely cytoplasmic. An exclusively cytoplasmic staining was documented for the tumour-associated foamy macrophages. Cancer cell reactivity was rather limited; only 3.2% of endometrial carcinomas expressed TP in more than 50% of the neoplastic cell population and only 12% expressed the enzyme in more than 10% of the cancer cells. By contrast, TP reactivity was frequent in the fibroblasts of the tumour supporting stroma and the fibroblasts/myometrial cells at the invading tumour front, where approximately 1/3 of the cases expressed TP in more than 50% of the respective constituent cells. A high TP reactivity in the stromal fibroblasts was significantly associated with the presence of foamy macrophages and an intense lymphocytic response. A high TP reactivity at the invading tumour front was significantly associated with an intense lymphocytic response and the adverse prognostic parameters of high tumour grade, deep myometrial invasion, advanced stage of disease and the non-endometrioid carcinomas. There was no significant association of cancer cell TP reactivity with any of the parameters studied, including nuclear p53 accumulation, cytoplasmic/perinuclear bcl-2 expression, microvessel density (MVD) and prognosis. Similarly, no relationship was established between fibroblastic or fibroblastic/myometrial TP reactivity and MVD. It is concluded that TP is not a major angiogenic factor in endometrial carcinomas. However, a prominent TP activity at the invading tumour front, which is probably induced by cytokines of histiocytic and lymphocytic origin, may promote tumour invasion and progression.

Clinical significance of angiogenic factors in breast cancer

Growth, progression, and metastasis of breast cancer, as well as of most of the other tumors, are angiogenesis-dependent processes. Several pro-angiogenic growth factors and endogenous inhibitors of angiogenesis have been identified and sequenced, and experimental studies suggest that angiogenic activity of a tumor may result from downregulation of inhibitors of angiogenesis or up-regulation of endothelial growth factors. The mechanisms leading to the alteration of the balance between positive and negative modulators of angiogenesis are only partially known. We are at the beginning of research to identify the more active angiogenic factors in human breast cancer, and little information is presently available on their clinical significance. Preliminary results suggest that among the known angiogenic peptides, both vascular endothelial growth factor (VEGF) and platelet-derived endothelial cell growth factor / thymidine phosphorylase (PD-ECGF/TP) have promising prognostic and, perhaps, predictive value. No data are available on the clinical value of co-determination of positive and negative regulators of angiogenesis to look at the angiogenic balance of each single tumor. Only a few studies have assessed the role of endogenous inhibitors of angiogenesis in human breast cancer, with results available only on thrombospondin-1 and -2 (TSP-1, -2). Finally, the determination of some integrins such as alpha6 and alphavbeta3 and of some other endothelial-adhesion molecules seems to be of potential prognostic value. Recognizing which are the more biologically active positive and negative angiogenic factors is the key for the identification not only of new prognostic markers but also of targets for antiangiogenic therapy in human breast cancer.

Anti-angiogenesis therapy and strategies for integrating it with adjuvant therapy

Tumor angiogenesis is critical for the growth of primary cancers above 1-2 mm in diameter. A major vascular growth factor is VEGF, and approaches to inhibit VEGF have shown encouraging results in pre-clinical studies. The mechanisms involved in switching on angiogenesis involve activation of oncogenes and upregulation of the hypoxia-sensing pathway. These provide novel targets for therapy. Many anti-angiogenic drugs are in clinical trial currently and there are problems in assessing these types of drugs if they only cause disease stabilisation. It will be important to develop methods to assess inhibition of vascular growth in vivo. New generations of anti-angiogenesis drugs such as endostatin of angiostatin, which are more potent, may cause tumor regression, but this has not yet been studied in patients. These approaches for advanced disease should be more successful when applied early in an adjuvant situation. This will also require careful monitoring of long-term toxicity.