Risa Tanaka

Kyushu University, Fukuoka-shi, Fukuoka-ken, Japan

Are you Risa Tanaka?

Claim your profile

Publications (16)33.22 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Using the recommended doses obtained from our previous phase 1 trial of a modified Saltz chemotherapy regimen for metastatic colorectal cancer (weekly irinotecan and bolus 5-fluorouracil/l-leucovorin for 3 weeks every 28 days), we performed the present phase 2 trial to evaluate efficacy and toxicity. A total of 29 patients with metastatic colorectal cancer were included. Our modified Saltz regimen was administered. The primary endpoint was overall response rate. Of the 29 patients, 11 had previous chemotherapy. A partial response occurred in 11 patients, stable disease in 16 patients, and progressive disease in two patients. Disease control rate was 93.1%. Response rates with and without previous treatment were 18.2% and 50%, respectively. Median progression-free survival was 17.3 months. The main hematologic toxicities were leukopenia (22.6%) and neutropenia (45.2%). No treatment-related deaths occurred. Our modified Saltz regimen exhibited sufficient efficacy, feasibility, and manageable toxicity as a therapeutic option for selected colorectal cancer patients.
    Advances in Therapy 02/2012; 29(3):287-96. · 2.13 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report a rare case of extrapulmonary small cell carcinoma arising in the palatine tonsil treated by combined chemotherapy with irinotecan/cisplatin following irradiation therapy. This chemotherapy regimen was recently found to be effective for small cell lung carcinoma. Our case is the first report of combined irinotecan/cisplatin chemotherapy to treat extrapulmonary small cell carcinoma of the oropharynx.
    Case Reports in Oncology 09/2011; 4(3):587-91.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The combination of an oral fluoropyrimidine derivative, S-1, and irinotecan is expected to be a promising regimen for advanced colorectal cancer. This study was performed to determine the maximum tolerated dose (MTD) and recommended dose (RD) of irinotecan combined with S-1 in a 3-week cycle regimen and to observe the safety and efficacy for patients with previously untreated advanced colorectal cancer. Eighty milligrams per m(2) of S-1 was given orally for 14 consecutive days and escalated doses of irinotecan were administered on days 1 and 8 every 3 weeks in the phase I trial. Forty patients were treated at the RD during the phase II trial. Forty-three patients were enrolled between February 2005 and March 2007. The dose-limiting toxicity was diarrhea and abdominal pain. The MTD of irinotecan was 100 mg/m(2) and the RD was determined to be 80 mg/m(2) of irinotecan combined with 80 mg/m(2) of S-1. The phase II trial showed that 22 of 40 patients achieved a complete or partial response and eight had stable disease. The overall response rate was 55.0%. The median progression-free survival time and median survival time were 6.7 and 21 months, respectively. There were no treatment-related deaths. The main toxicities were leukopenia, neutropenia, anorexia and diarrhea. This study suggests the combination of irinotecan and S-1 repeated every 3 weeks is tolerable and effective for patients with previously untreated advanced colorectal cancer.
    Cancer Science 12/2010; 101(12):2591-5. · 3.48 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A 50-year-old woman was admitted because of abdominal fullness due to bilateral ovarian tumors, pleural effusion, and ascites associated with breast cancer. Although chemotherapy and the removal of ascites were performed periodically, the ascites did not disappear. The cytology of the ascites did not indicate malignancy. Pseudo-Meigs' syndrome caused by metastasis to both ovarian tumors was suspected. The patient underwent a bilateral salpingo-oophorectomy, and the pathological diagnosis was bilateral metastatic ovarian tumors from breast cancer. The ascites and pleural effusion resolved after the surgery, with the consequent improvement of the patient's quality of life; however, she unfortunately died 4 months later due to hepatic failure caused by multiple metastases.
    Surgery Today 12/2010; 40(12):1148-51. · 0.96 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The combination of 5-fluorouracil (5-FU) and cisplatin (CDDP) has been reported to be active against metastatic gastric cancer (MGC) and great synergy has been shown in vivo and in vitro when 5-FU precedes CDDP. The sequential combination of S-1 (tegafur, oxonic acid, 5-chloro-2,4-dihydroxypyridine) followed by CDDP for MGC was investigated. A phase I trial applying increasing doses of oral administration of S-1 (65-80 mg/m(2)) for 21 days and increasing doses of CDDP (60-80 mg/m(2)) on day 22 every 35 days was conducted in order to determine the maximum tolerated dose (MTD) and recommended phase II dose. Patients with metastatic or recurrent gastric cancer, no prior chemotherapy, measurable disease, ECOG performance status less than 3 and adequate organ functions were eligible for the study. Three patients were treated at each dose level with escalation based on toxicity. Fifteen patients were included and evaluated for dose-limiting toxicity (DLT) and MTD. DLT included NCICTC grade 3 anorexia and fatigue in patients treated at S-1 80 mg/m(2) and CDDP 80 mg/m(2) (dose level 5). The other toxicities, grade 3 or higher, included neutropenia (grade 3) and nausea/vomiting (grade 3). Non-hematological toxicities were grade 1/2 and included diarrhea, nausea and stomatitis. There was no treatment-related mortality. Therefore, the recommended dose was a combination of S-1 at 80 mg/m(2) and CDDP at 70 mg/m(2). This sequential administration of S-1 and CDDP every 35 days is tolerable and warrants a phase II trial. A multicenter phase II study is currently under way.
    Anticancer research 06/2009; 29(5):1727-32. · 1.71 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Although gefitinib, a selective inhibitor of epidermal growth factor receptor (EGFR) tyrosine kinase, has been demonstrated to exhibit its antitumor activity by the blockade of EGF receptor, the role of signaling pathways downstream of EGFR in gefitinib sensitivity remains unknown. In this study, we investigated the mechanistic role of Src and Ras, major oncogene products implicated in the pathogenesis of many human cancers in gefitinib sensitivity. Using parental and v-src- or c-H-ras-transfected HAG-1 human gallbladder adenocarcinoma cell lines, effects of gefitinib on cytotoxicity, cell cycle purtubation and apoptosis, and tyrosine phosphorylation of EGFR, Akt, and Erk were determined by WST-1 assay, flow cytometry, and Western blots, respectively. Activated Ras and Src conferred a strong resistance to gefitinib by nearly 30-fold and 200-fold, respectively. Gefitinib induced accumulation of cells in the G0/G1 phase of the cell cycle at 24-h, with progressive expansion of apoptotic cell population in parental HAG-1 cells, but these effects were completely abolished in v-src- or c-H-ras-transfected cell line. Upon gefitinib treatment, EGFR activation and subsequent downstream activation through Erk and Akt were significantly inhibited in HAG-1 cells. By contrast, gefinitib failed to inhibit the activation of both Akt and Erk in v-src-transfected cells and Erk, but not Akt in c-H-ras-transfected cells, despite the blockade of EGFR activation in these respective cell lines. Treatment of v-src-transfected cells with herbimycin A, a Src tyrosine kinase inhibitor, partially reversed the gefitinib resistance, with concomitant inhibition of Akt and Erk. Our results suggest that activated Ras and Src could induce gefitinib resistance by activating either or both of Akt and Erk signaling pathways, thus providing a strategic rationale for assessment of these specific signaling molecules downstream of EGFR to customize treatment.
    Cancer Chemotherapy and Pharmacology 12/2006; 58(5):577-84. · 2.80 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Although continuous infusion of 5-fluorouracil (5-FU) has been clinically demonstrated to be superior to bolus administration, the mechanistic difference between the treatments still remains unclear. Here, we investigated in vitro whether there were any differences in the metabolism and activity of 5-FU between these schedules. To simulate bolus and infusional treatments of 5-FU, HST-1 human squamous carcinoma cells were treated with short-term, high-doses and long-term, low-doses so that the area under the curve (AUC) of 5-FU became equivalent between both schedules, and compared the cytotoxicity, fluorinated RNA (F-RNA) levels, 5-fluorodeoxyuridine monophosphate (FdUMP) content and thymidylate synthase (TS) activity. F-RNA and FdUMP were measured by capillary gas chromatography-mass spectrometry and competitive ligand-binding assay, respectively. The [H]FdUMP binding site in TS was determined as an index of the amount of TS using the radio-binding assay. Long-term, low-dose treatment of 5-FU was found to be 1.3-1.7 times more cytotoxic than the short-term, high-dose treatment. F-RNA content increased as the AUC of 5-FU was increased and was 2-4 times significantly higher in the cells treated with the long-term, low-dose than those with the short-term, high-dose schedule, indicating that the levels of F-RNA are AUC and schedule dependent. In contrast, there were no significant differences in FdUMP levels, TS activity and TS inhibition rate between the schedules. These data suggest that the superior activity of 5-FU administered long-term, low-dose over short-term, high-dose could be explained by more 5-FU incorporated into RNA during a long-term, low-dose exposure, thus providing a strategic rationale for the clinical advantage of continuous infusion over bolus administration.
    Anti-Cancer Drugs 05/2006; 17(4):439-43. · 2.23 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In order to define the most effective combination schedule of oxaliplatin (L-OHP) and 5-fluorouracil (5-FU), we investigated the in vitro interaction between these drugs in a panel of four human gastric adenocarcinoma cell lines (MKN-1, NUGC-3, NUGC-5 and AZ-521). Cytotoxic activity was determined by the WST-1 assay. Different schedules of the two drugs were compared and evaluated for synergism, additivity or antagonism with a quantitative method based on the median-effect principle of Chou and Talalay. Cell cycle perturbation and apoptosis were evaluated by flow cytometry. Simultaneous and sequential treatments of L-OHP followed by 5-FU exhibited synergistic effects in all four cell lines, whereas the reverse sequence yielded a clear antagonism. 5-FU exclusively arrested cells at the G0/G1 phase, and L-OHP at the G0/G1 and G2/M phases. Apoptosis was most prominent when cells were treated simultaneously or in a sequence of L-OHP followed by 5-FU, producing apoptosis in the majority of treated cells (55.5-61.5%). In contrast, the reverse sequence yielded only 20% induction of apoptosis, the rate being not significantly different from those induced by each drug singly. Moreover, this sequence dependence was further confirmed by the experiment which compared the total number of NUGC-3 cells 7 days after these combination schedules. These findings suggest that the interaction of 5-FU and L-OHP could be highly schedule dependent, with the most efficacious interaction observed in simultaneous combination and that 5-FU followed by L-OHP would not be recommended in clinical trials for patients with advanced gastric cancer.
    Anti-Cancer Drugs 05/2006; 17(4):445-53. · 2.23 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Although gefitinib, a selective inhibitor of epidermal growth factor receptor (EGFR) tyrosine kinase, has been clinically demonstrated to be effective for certain cancer cell types, the molecular mechanisms of the anti-tumor activity have not been fully elucidated. In this study, we investigated the mechanism of gefitinib-induced growth inhibition and apoptosis in HAG-1 human gallbladder adenocarcinoma cells. Treatment of gefitinib at a dose of 1 microM resulted in a significant growth inhibition, and the cell number irreversibly declined after 72-h incubation, with a progressive expansion of apoptotic cell population over 120-h. Following 2-h treatment, gefitinib significantly inhibited EGFR autophosphorylation and subsequent downstream signaling pathway through Erk and Akt, and induced accumulation of cells in the G0/G1 phase of the cell cycle at 24-h, accompanied by a concomitant increase in p21 transcript and increased expression of p27. Gefitinib did not affect the amount of total and phosphorylated p53 at serine 15, but upregulated the expression of total Bax, with subsequent increase in p18 Bax, an active form of Bax. The expression of Bcl-2 and Bad was unchanged. An increase in gefitinib-induced expression of total Bax might be due to the decreased degradation of Bax, because the level of Bax mRNA has not been altered by gefitinib treatment. Gefitinib promoted the cleavage of full-length p21 Bax into p18 Bax in mitochondrial-enriched fraction, a characteristic feature of Bax activation toward apoptosis. Moreover, blockade of Bax by using anti-Bax small interfering double stranded RNA (siRNA) significantly reduced gefitinib-induced apoptosis. Taken together, these data suggest a critical role of p18 Bax in gefitinib-induced apoptosis.
    Journal of Cellular Biochemistry 04/2006; 97(4):724-34. · 3.06 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A great synergy has been reported in a number of preclinical studies when 5-fluorouracil (5-FU) precedes cisplatin (CDDP). The objective of this study was to determine the feasibility of ambulatory continuous infusion of 5-FU followed by CDDP through hepatic artery for metastatic colorectal cancer. Seventeen patients with unresectable liver metastases, who underwent primary tumor resection, were treated with 5-FU (450 mg/m2/day) for seven consecutive days followed by CDDP (100 mg/body/week) for seven consecutive days, each administered continuously by using a balloon pump via Infuse-A-Port catheter inserted into common hepatic artery. The doses of drugs were reduced 20% in patients older than 70 years. The treatment was repeated every 4-6 weeks until disease progression. Of 17 assessable patients, nine patients showed PR (53%; 95% CI, 29.3-76.7%) and eight patients had SD (47%; 95% CI, 23.3-70.7%), with disease control rate of 100%. The median overall survival was 26 months (95% CI: 17.5-41 months) and TTP 14 months (95% CI: 11-20.3 months). Two patients (11.8%), who showed progression due to collateral feeding arteries, responded to HAI again after occlusion. Grade 3 toxicity included leukopenia (12%) and anemia (24%). Grade 4 toxicity was absent. Four patients (23.5%) progressed at extrahepatic sites. This sequential combination of 5-FU followed by CDDP through hepatic artery is active and safe in an outpatient setting, and warrants further multi-institutional study, although prevention of micrometastasis would be mandatory to further prolong overall survival.
    Cancer Chemotherapy and Pharmacology 02/2006; 57(1):114-9. · 2.80 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In July 2003, a 59-year-old man underwent a right hemicolectomy for sigmoid colon cancer. Hepatic intraarterial injection therapy with 5-FU/CDDP was not only ineffective against a liver metastasis but a lung metastasis was also found, and therefore systemic chemotherapy with CPT-11/5-FU/l-LV (IFL) was administered. After onetime IFL therapy, the CPT-11 was withheld due to ileus. Although 5-FU/l-LV therapy was administered, it was ineffective. IFL therapy was again performed, with the dose decreased by 20%, as part of ambulatory treatment. Not only the liver metastasis but also the lung metastasis decreased significantly in size after one course. In addition, no severe adverse reactions were observed during the treatment, which enabled the therapy to be continued as part of an ambulatory regimen. The results suggest that IFL therapy is effective against colon cancer with lung/liver metastasis and can be administered as part of ambulatory treatment.
    Gan to kagaku ryoho. Cancer & chemotherapy 10/2005; 32(9):1339-42.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The interaction between CPT-11 and oxaliplatin, a new platinum derivative that has a great antitumor activity against colon cancer, has not been determined in gastric cancer cells. In this study, we investigated in vitro cytotoxic activity of oxaliplatin alone or in combination with SN-38, an active metabolite of CPT-11, using different exposure schedules in three human gastric cancer cell lines (AZ-521, MKN-45, and NUGC-4). Cytotoxicity was determined by WST-1 assay. Different treatment schedules of the two drugs were compared and evaluated for synergism, additivity, or antagonism with a quantitative method based on the median-effect principle of Chou and Talalay. Cell cycle perturbation was evaluated by flow cytometry. In 24-h exposure, simultaneous administration of oxaliplatin and SN-38 showed a synergistic effect in AZ-521 and NUGC-4 cells, and an additive effect in MKN-45 cells. Greater than additive effects were observed in all of the cell lines when cells were treated with oxaliplatin followed by SN-38, whereas such effects were observed only in NUGC-4 cells in the reverse sequence. Flow cytometric analyses at IC(50) indicated that apoptosis was most prominent in simultaneous exposures with accumulation of cells in both G(0)/G(1) and S phases. These results suggest that SN-38 may kill the cells recovering from the G(1) block produced by oxaliplatin as they progress into the S phase. Simultaneous administration appears most active in gastric cancer cell lines. These results may provide important information for a clinical trial of oxaliplatin and CPT-11 combination for patients with gastric cancer.
    Oncology Reports 10/2005; 14(3):683-8. · 2.30 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To define the most effective combination schedule of paclitaxel and nedaplatin, a new platinum derivative, we investigated the in vitro interaction between these drugs in AZ-521 and NUGC-4 gastric adenocarcinoma and KSE-1 esophageal squamous carcinoma cell lines. Cytotoxic activity was determined by the WST-1 assay. Different treatment schedules of the two drugs were compared and evaluated for synergism, additivity, or antagonism using a quantitative method based on the median-effect principle of Chou and Talalay. Cell-cycle perturbation and apoptosis were evaluated by means of flow cytometry. Upon 24-h sequential exposure, the sequence paclitaxel followed by nedaplatin induced greater than additive effects in all of the cell lines, with synergistic interactions in NUGC-4 and KSE-1 cells. By contrast, antagonistic effects were observed with the reverse sequence. Simultaneous treatment resulted in either a synergistic or antagonistic effect, depending on the cell line. Therefore, the sequence paclitaxel followed by nedaplatin appears most active, at least in these three cell lines. Flow cytometric analyses at IC50 indicated that paclitaxel induced G2/M arrest with subsequent induction of apoptosis (56%) in the sub-G1 phase. When paclitaxel preceded nedaplatin, apoptosis was most prominent (70%) with pronounced G2/M arrest. By contrast, the reverse sequence yielded only 28% induction of apoptotic cells, with almost identical cell-cycle distribution patterns to those observed with nedaplatin alone, indicating that the activity of paclitaxel is abolished by pretreatment with nedaplatin. Our findings suggest that the interaction of nedaplatin and paclitaxel is highly schedule dependent and that the sequential administration of paclitaxel followed by nedaplatin should be thus incorporated into the design of a clinical trial.
    Cancer Chemotherapy and Pharmacology 10/2005; 56(3):279-85. · 2.80 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In order to define the most effective administration schedule of the combination of paclitaxel and oxaliplatin, we investigated the in vitro interaction between these drugs in a panel of three human cancer cell lines (AZ-521 gastric adenocarcinoma cell line, HST-1 tongue squamous carcinoma cell line, and KSE-1 esophageal squamous carcinoma cell line). Cytotoxic activity was determined by the WST-1 assay. Different administration schedules of the two drugs were compared and evaluated for synergism, additivity, or antagonism with a quantitative method based on the median-effect principle of Chou and Talalay. Cell cycle perturbation and apoptosis were evaluated by flow cytometry. Simultaneous treatment of cells with paclitaxel and oxaliplatin showed greater than additive effects. Upon 24-h sequential exposure, the sequence of paclitaxel followed by oxaliplatin showed synergistic effects in AZ-521 and HST-1 cells, and greater than additive effects in KSE-1 cells, while the opposite sequence yielded marked antagonistic effects in all three cell lines. Flow cytometric analysis indicated that paclitaxel induced G(2)/M arrest with subsequent induction of apoptosis in the sub-G(1) phase. Apoptosis was most prominent when paclitaxel preceded oxaliplatin, which produced apoptosis in the majority of treated cells (75%). By contrast, the reverse sequence yielded only 39% induction of apoptotic cells, the rate being not different from those induced by each drug singly. Our findings suggest that the interaction of paclitaxel and oxaliplatin is highly schedule-dependent and that the sequential administration of paclitaxel followed by oxaliplatin should thus be incorporated into the design of a clinical trial.
    Cancer Chemotherapy and Pharmacology 07/2005; 55(6):595-601. · 2.80 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Effects of two clinically used liquid diets on toxicity and antitumor activity of methotrexate (MTX) were investigated in Sprague-Dawley (SD) rats and tumor-bearing mice, respectively. Diets tested were commercially available formulas enriched either with soybean and omega-3 fatty acids or with casein. The soybean-containing diet offered significant protection against MTX toxicity in rats compared with the casein-containing diet, completely alleviating MTX-induced anorexia, diarrhea, and weight loss, when ingested as the sole diet and fed 7 days prior to and 7 days following intraperitoneal MTX injection. As a result, 90% of rats were alive on soybean-containing diet while all rats were dead on casein-containing diet. Histologic examination of the small intestine of MTX-treated rats revealed that the soybean-containing diet significantly prevented loss of mucosal villus tips compared to the casein-containing diet. Pharmocokinetic examination indicated that plasma MTX concentrations were similar for rats in the two diet-defined groups. No significant differences were observed between diets in survival of mice injected with L1210 mouse leukemia cells and subsequently with MTX. Thus the soybean-containing diet appeared to be superior to the casein-containing diet in preventing gastrointestinal toxicity while preserving antitumor activity. A soybean diet enriched in omega-3 fatty acids may be a useful adjunct to MTX treatment of human cancers.
    Oncology Reports 08/2004; 12(1):41-5. · 2.30 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Detachment of anchorage-dependent normal epithelial cells from their substratum causes the type of apoptosis known as anoikis, whereas malignant cells can proliferate independently of anchorage. Because src and ras oncogenes are activated in many human cancers, we investigated their role and downstream signaling pathways in anoikis resistance, using HAG-1 human epithelial cells transfected with v-src or activated H-ras. Consequently, anchorage-dependent mock- or ras-transfected cells underwent anoikis. In contrast, anchorage-independent v-Src-transformed cells did not exhibit such apoptotic features. Focal adhesion kinase (FAK), a transducer of integrin, was only activated in v-Src-transformed cells. Herbimycin A, an Src kinase inhibitor, reduced tyrosyl phosphorylation of FAK and reversed resistance to anoikis. However, both protein kinase C (PKC) and phophatidylinositol-3 (PI-3) kinase inhibitors failed to induce anoikis. These data suggest that the ability of activated Src to prevent anoikis may be mediated by Src to a downstream signaling pathway involving FAK, but not Ras, PI-3 kinase, or PKC.
    Cell Biology International 02/2003; 27(5):415-21. · 1.64 Impact Factor