Showing papers by "Masakazu Toi published in 2005"

Nuclear factor-κB inhibitors as sensitizers to anticancer drugs

Abstract: The cytotoxicity of chemotherapeutic agents is attributed to apoptosis. Acquired resistance to the effects of chemotherapy has emerged as a significant impediment to effective cancer therapy. One feature that cytotoxic treatments of cancer have in common is their activation of the transcription factor nuclear factor-kappaB (NF-kappaB), which regulates cell survival. NF-kappaB activation suppresses the apoptotic potential of chemotherapeutic agents and contributes to resistance. What evidence is there that inhibitors of NF-kappaB might promote apoptosis in cancer cells and can NF-kappaB inhibitors be used to overcome resistance to chemotherapeutic agents?

Significance of HDAC6 regulation via estrogen signaling for cell motility and prognosis in estrogen receptor-positive breast cancer.

Abstract: Histone deacetylase (HDAC) 6 is a subtype of the HDAC family; it deacetylates alpha-tubulin and increases cell motility. Here, we investigate the impact of an alteration of HDAC6 expression in estrogen receptor alpha (ER)-positive breast cancer MCF-7 cells, as we identified that HDAC6 is a novel estrogen-regulated gene. MCF-7 treated with estradiol showed increased expression of HDAC6 mRNA and protein and a four-fold increase in cell motility in a migration assay. Cell motility was increased to the same degree by stably transfecting the HDAC6 expression vector into MCF-7 cells. In both cases, the cells changed in appearance from their original round shape to an axon-extended shape, like a neuronal cell. This HDAC6 accumulation caused the deacetylation of alpha-tubulin. Either the selective estrogen receptor modulator tamoxifen (TAM) or the pure antiestrogen ICI 182,780 prevented estradiol-induced HDAC6 accumulation and deacetylation of alpha-tubulin, leading to reduced cell motility. Tubacin, an inhibitory molecule that binds to the tubulin deacetylation domain of HDAC6, also prevented estradiol-stimulated cell migration. Finally, we evaluated HDAC6 protein expression in 139 consecutively archived human breast cancer tissues by immunohistochemical staining. The prognostic analyses for these patients revealed no significant differences based on HDAC6 expression. However, subset analysis of ER-positive patients who received adjuvant treatment with TAM (n = 67) showed a statistically significant difference in relapse-free survival and overall survival in favor of the HDAC6-positive group (P < 0.02 and P < 0.05, respectively). HDAC6 expression was an independent prognostic indicator by multivariate analysis (odds ratio = 2.82, P = 0.047). These results indicate the biological significance of HDAC6 regulation via estrogen signaling.

Angiogenic inhibitors: A new therapeutic strategy in oncology

Abstract: Based on preclinical data, it has been suggested that antiangiogenic compounds could improve cytotoxic drug delivery because of their effects on tumor endothelium. Most of the early clinical testing of these agents was conducted in patients with advanced disease resistant to standard therapies, and while some of the phase III trial data were disappointing, recent studies validated in large clinical trials with the anti-VEGF antibody, bevacizumab, demonstrated significant clinical benefit and renewed enthusiasm for this therapeutic strategy. This review highlights the challenges related to choosing appropriate strategies for the selection of patients, study design, and choice of appropriate endpoints for the study development of these agents. Angiogenesis is a multistep, complex and tightly regulated process that is necessary for tumor growth and metastasis. Based on data of preclinical models, several antiangiogenic compounds has been shown to modify activated tumor endothelium, which suggests that these compounds can improve cytotoxic drug delivery. Such agents have entered clinical trials as single agents or in combination with cytotoxic drugs, and have shown promising antitumor activity. The pharmacodynamic and pharmacokinetic characteristics of antiangiogenic drugs are reviewed here. Most of the early clinical testing of these agents was conducted in patients with advanced disease resistant to standard therapies. Phase III trials compared the efficacy of standard chemotherapy alone with standard chemotherapy in combination with an experimental angiogenesis inhibitor. Although some of these studies were negative or controversial, recent studies validated in large clinical trials with an anti-vascular endothelial growth factor antibody demonstrated significant clinical benefit and renewed enthusiasm for this therapeutic strategy. This review describes the clinical studies of antiangiogenic agents and highlights the challenges related to choosing appropriate strategies for the selection of patients, study design and choice of appropriate endpoints for the studies' development.

Thymidine phosphorylase (platelet-derived endothelial-cell growth factor) in cancer biology and treatment

Abstract: Thymidine phosphorylase (TP) is often induced in the tumour microenvironment by physiological and chemical stress. Its induction protects cells from apoptosis and helps cell survival by stimulating nucleoside metabolism and angiogenesis. Chemotherapy often upregulates TP, which acts in cell rescue; this result indicates that TP is a crucial therapeutic target. Clinical trials for metastatic diseases have shown that TP-targeting chemotherapy with fluorouracil derivatives greatly improves the effectiveness of conventional chemotherapy for not only response but also prognosis. This new idea, the improvement of TP-inducible therapy with TP-targeting therapy, should be further investigated for early disease states, and inhibitors of TP warrant extensive investigation.

Association between intratumoral free and total VEGF, soluble VEGFR-1, VEGFR-2 and prognosis in breast cancer.

Abstract: Vascular endothelial growth factor (VEGF) receptors consist of three cell-membrane type receptors (VEGFR-1, VEGFR-2 and VEGFR-3), and soluble form of VEGFR-1 (sVEGFR-1), an intrinsic negative counterpart of the VEGF. In this study, we measured intratumoral protein levels of free and total VEGF, VEGFR-2 and sVEGFR-1 from 202 primary breast cancer tissues and examined their prognostic values. A significant inverse correlation was found between free or total VEGF and oestrogen receptor (ER) status (P=0.042 and 0.032, respectively). A univariate analysis showed that low sVEGFR-1 and high total VEGF were significantly associated with poor prognosis in disease-free survival (DFS) and overall survival (OS). The ratio of sVEGFR-1 to total VEGF was a strong prognostic indicator (DFS: P=0.008; OS: P=0.0002). A multivariate analysis confirmed the independent prognostic values of total VEGF and the ratio of sVEGFR-1 to total VEGF. In subgroup analysis, total VEGF was a significant prognostic indicator for ER-positive tumours but not for ER-negative tumours, whereas sVEGFR-1 was significant for ER-negative tumours but not for ER-positive tumours. In conclusion, the intratumoral sVEGFR-1 level, VEGF level and the ratio of sVEGFR-1 to total VEGF are potent prognostic indicators of primary breast cancer, and might be relevant to ER status.

Targeting of Nuclear Factor κB Pathways by Dehydroxymethylepoxyquinomicin, a Novel Inhibitor of Breast Carcinomas: Antitumor and Antiangiogenic Potential In vivo

Abstract: We previously designed and synthesized the new nuclear factor kappaB (NF-kappaB) inhibitor dehydroxymethylepoxyquinomicin (DHMEQ) derived from the structure of the antibiotic epoxyquinomicin C. We looked into the effect of DHMEQ on cellular phenotypes and tumor growth in mice injected with human breast carcinoma cell line MDA-MB-231 or MCF-7. In estrogen-independent breast adenocarcinoma cell line MDA-MB-231, NF-kappaB is constitutively activated. The addition of DHMEQ (10 microg/mL) completely inhibited the activated NF-kappaB for at least 8 hours. On the other hand, NF-kappaB is not activated in estrogen-dependent MCF-7 cells. In this cell line, DHMEQ completely inhibited the tumor necrosis factor-alpha-induced activation of NF-kappaB. DHMEQ did not inhibit the degradation of IkappaB but inhibited the nuclear translocation of NF-kappaB by both p65/p50 and RelB/p52 pathways. MDA-MB-231 cells secrete interleukin (IL)-6 and IL-8 without stimulation, and DHMEQ decreased the secretion levels of both cytokines. When MDA-MB-231 or MCF-7 cells were stimulated by tumor necrosis factor-alpha, the inhibitory effects of DHMEQ were still maintained. I.p. administration of DHMEQ (thrice a week) significantly inhibited the tumor growth of MDA-MB-231 (12 mg/kg) or MCF-7 (4 mg/kg) in severe combined immunodeficiency mice. No toxicity was observed during the experiment, including the loss of body weight. An immunohistological study on resected MCF-7 tumors showed that DHMEQ inhibited angiogenesis and promoted apoptosis. Furthermore, in Adriamycin-resistant MCF-7 cells highly expressing multidrug resistance gene-1, DHMEQ also exhibited the above capability, including down-regulation of IL-8. Thus, DHMEQ might be a potent drug for the treatment of various breast carcinomas by inhibiting the NF-kappaB activity.

Clinical significance of estrogen receptor β in breast cancer

Abstract: Ever since the estrogen receptor (ER) β was discovered in 1996, we have been trying to determine its value as a prognostic and/or predictive factor in breast cancer and its potential as a novel target for pharmacological intervention. Recent progress in cellular experiments has shown that ERβ works as counter partner of ERα through inhibition of the transactivating function of ERα by heterodimerization, distinct regulation on several specific promoters by ERα or ERβ, and ERβ-specific regulated genes which are probably related to its anti-proliferative properties. Accumulated data from protein studies in breast cancer tissues indicate that positive expression of ERβ appears to correlate with a favorable prognosis. Although the number of studies is small, a positive response to tamoxifen treatment is observed in both ERα- and ERβ-positive populations. The significance of ERβ2/cx, a splicing variant of ERβ, remains controversial and needs to be analyzed in further studies. We postulate that a combined evaluation of ERβcx with progesterone receptor may help the stratification of ERα-positive breast cancer. Epidemiological studies of hormone replacement therapy and isoflavone (genistein) consumption indicate the possible contribution of ERβ-specific signaling in breast cancer prevention. A selective estrogen receptor modulator, which works as an antagonist of ERα and an agonist of ERβ, may be a promising chemo-preventive treatment.

N(1),N(12)-Diacetylspermine as a sensitive and specific novel marker for early- and late-stage colorectal and breast cancers.

Abstract: Purpose: N 1 , N 12 -diacetylspermine (DiAcSpm) in the urine of colorectal and breast cancer patients was examined to establish its usefulness as a novel diagnostic tool for detecting these cancers at clinically early stages. Experimental Design: Urine samples from 248 colon cancer patients and 83 breast cancer patients as well as 51 patients with benign gastrointestinal diseases treated in Tokyo Metropolitan Komagome Hospital during the period of August 1999 to January 2004 were collected. DiAcSpm was analyzed by ELISA and its sensitivity for malignant conditions was compared with that of serum carcinoembryonic antigen (CEA), CA19-9, and CA15-3. Results: The sensitivity of urinary DiAcSpm for colon cancer patients ( n = 248) was 75.8% (mean ± 2 SD for 52 healthy controls as a cutoff value), which was markedly higher than the sensitivities of serum CEA (39.5%, P P P P P = 0.0032) and CA15-3 (37.3%, P = 0.0032). DiAcSpm was elevated in 28% of tumor-node-metastasis stage I + II patients, whereas only 3% ( P = 0.0064) and 0% ( P = 0.001) of these patients were CEA- and CA15-3–positive, respectively. Conclusion: The observations indicate that urinary DiAcSpm is a more sensitive marker than CEA, CA19-9, and CA15-3 and that it can efficiently detect colorectal and breast cancers at early stages.

Late phase II clinical study of vinorelbine monotherapy in advanced or recurrent breast cancer previously treated with anthracyclines and taxanes.

Abstract: Background : At present, it is one of the most important issues for the treatment of breast cancer to develop the standard therapy for patients previously treated with anthracyclines and taxanes. With the objective of determining the usefulness of vinorelbine monotherapy in patients with advanced or recurrent breast cancer after standard therapy, we evaluated the efficacy and safety of vinorelbine in patients previously treated with anthracyclines and taxanes. Methods: Vinorelbine was administered at a dose level of 25 mg/m 2 intravenously on days 1 and 8 of a 3 week cycle. Patients were given three or more cycles in the absence of tumor progression. A maximum of nine cycles were administered. Results: The response rate in 50 evaluable patients was 20.0% (10 out of 50; 95% confidence interval, 10.0-33.7%). Responders plus those who had minor response (MR) or no change (NC) accounted for 58.0% [10 partial responses (PRs) + one MR + 18 NCs out of 50]. The Kaplan-Meier estimate (50% point) of time to progression (TTP) was 115.0 days. The response rate in the visceral organs was 17.3% (nine PRs out of 52). The major toxicity was myelosuppression, which was reversible and did not require discontinuation of treatment. Conclusion: The results of this study show that vinorelbine monotherapy is useful in patients with advanced or recurrent breast cancer previously exposed to both anthracyclines and taxanes.

Importance of thymidine phosphorylase expression in tumor stroma as a prognostic factor in patients with advanced colorectal carcinoma

Abstract: Thymidine phosphorylase (TP) is a unique enzyme involved not only in angiogenesis, but in 5-fluorouracil (5-FU) metabolism as well. TP is produced by both tumor and stromal cells. The aim of this study was to reveal the clinical implication of TP localization in tumor tissues. Advanced colorectal cancer specimens (n=97) were prepared for immunohistochemical staining using monoclonal antibodies against TP, p53, vascular endothelial growth factor (VEGF), factor VIII, CD68 and thymidylate synthase (TS). Clinicopathological factors and the clinical prognosis were examined for each indicator. High tumor TP expression and high stromal TP expression were observed in 38% (36/95 cases) and 49% (47/95 cases) of the cases, respectively. High tumor TP expression tended to correlate with microvessel density (MVD) (p=0.0511). Among patients who underwent curative resection, those with high stromal TP expression had a favorable prognosis (p=0.0127). High stromal TP status was also a strong prognostic factor in the group receiving adjuvant 5-FU derivatives (p=0.0222). TP produced by tumor cells has a stimulatory effect on tumor angiogenesis, while that produced by stromal cells plays an entirely different role. The latter may enhance the anticancer effect of 5-FU via its catalyzed function.

Enhancement of the caspase-independent apoptotic sensitivity of pancreatic cancer cells by DHMEQ, an NF-κB inhibitor

Abstract: The effects of the nuclear factor (NF)-kappaB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), combined with tumor necrosis factor (TNF)-alpha were evaluated in PK-8 pancreatic cancer cells. NF-kappaB was activated by TNF-alpha; however, the administration of DHMEQ abrogated its transcriptional activity. The addition of DHMEQ to TNF-alpha markedly induced apoptosis in PK-8 cells with down-regulation of anti-apoptotic c-FLIP and survivin. Combined treatment significantly suppressed cell viability in vitro, and the anti-tumor effect of DHMEQ was also significant in vivo. We investigated the apoptosis signaling pathway involved in these cell killing effects. Truncated Bid was produced by activated caspase-8, and the subsequent depolarization of the mitochondrial membrane potential (Delta Psi m) peaked at 6 h. Then, the activity of caspase-3 was up-regulated 8-fold. Z-VAD-fmk (a pan-caspase inhibitor) perfectly inhibited the up-regulation of caspase-3 but failed to reverse the cell viability. The above findings indicated that the growth inhibitory effect of combined treatment largely depended on mitochondria-associated caspase-independent apoptosis. The intracellular behavior of apoptosis-inducing factor (AIF) following depolarization of Delta Psi m suggested that AIF executed such a caspase-independent apoptosis. Interestingly, caspase-dependent apoptosis appeared within 6 h, whereas the caspase-independent apoptosis lagged. Thus, the addition of DHMEQ to TNF-alpha was capable of inducing caspase-independent apoptosis in pancreatic cancer cells. Once caspase-independent apoptosis was induced, the apoptosis demonstrated powerful cytotoxicity. Therefore, DHMEQ in combination with TNF-alpha may be a promising treatment for pancreatic cancer.

Trastuzumab: updates and future issues

Abstract: Trastuzumab has had an enormous impact on the clinical management of breast cancer: the survival of Her-2-positive metastatic breast cancer patients has improved significantly and tumor Her-2 status has been built into the decision-making tree for primary breast cancer patients. Several pioneering studies have shown that trastuzumab-combined chemotherapy elicits high levels of pathological complete response in the neoadjuvant setting. Currently, therefore, a more precise understanding of the mechanisms of therapeutic response is needed so that trastuzumab-based therapies can be optimized more individually. It might also be important to investigate, with greater depth, the interaction between the Her-axis and the hormone-axis. This short review describes and discusses these topics.

A Japanese phase I study of continuous oral capecitabine in patients with malignant solid tumors.

Abstract: Background This study aimed to evaluate the tolerability and pharmacokinetics of capecitabine, given twice daily for 6 weeks without interruption, and to identify the maximum tolerated dose (MTD) and the suggested phase II schedule.

Cost-effectiveness of letrozole versus tamoxifen as first-line hormonal therapy in treating postmenopausal women with advanced breast cancer in Japan.

Abstract: The objective of this study is to evaluate the cost-effectiveness of letrozole compared with tamoxifen as first-line therapy in post-menopausal women with advanced breast cancer in Japan. A Markov analytical model was developed to estimate life-year (LY) expectancies, using key transition probabilities obtained from the results of a multinational phase III trial, a literature review and a Japanese medical expert panel. Direct medical costs were estimated, from the payer's perspective, using the expected resource utilization provided by the expert panel, the medical fee table and drug tariff under the national health insurance system. The expected overall life-years (LYs) obtained were 3.68 years for letrozole arm and 3.09 years for tamoxifen arm, showing incremental LYs of 0.59 years in patients receiving letrozole. The total expected costs were 3,644,588 yen (33,133 US dollars) for letrozole arm and 3,322,111 yen (30,201 US dollars) for tamoxifen arm, resulting in a mean incremental cost-effectiveness ratio (ICER) of 546,571 yen (4,969 US dollars) per life-year gained, while the 5 th percentile of ICER showed letrozole dominating tamoxifen and the 95th percentile was 2,310,593 yen (21,005 US dollars). The results suggest that letrozole is a clinically beneficial and cost-effective treatment option when compared with tamoxifen in first-line therapy for advanced breast cancer in Japan.