Efficacy and Safety of Additional S-1 Chemotherapy to S-1 Plus Oxaliplatin Regimen Chemotherapy for Stage III Gastric Carcinoma after Radical Resection.

OBJECTIVE: To investigate the efficacy and safety of additional S-1 chemotherapy to S-1 plus oxaliplatin (SOX) regimen chemotherapy for Stage III gastric carcinoma (GC) after radical resection. PATIENTS AND METHODS: A total of 161 patients who were pathologically diagnosed as Stage III GC after D2 gastrectomy and received SOX regimen adjuvant chemotherapy between January 2012 and April 2016 were included in this retrospective study. SOX regimen postoperative chemotherapy was composed of Oxaliplatin and S-1, administrated every 3 weeks for 8 scheduled courses. After SOX chemotherapy, 76 patients preferred additional chemotherapy with S-1 (the ACT group), while additional S-1 chemotherapy was not given to the other 85 patients (control group). The ACT with S-1 was administrated every 3 weeks for 8 scheduled courses. Treatment was terminated in case of life-threatening adverse events or tumor progression, or patients' demand for termination. Progression-free survival (PFS), overall survival (OS), and adverse events were analyzed. RESULTS: ACT group obtained markedly improved 3-year PFS [p = 0.04; hazard ratio (HR) for disease progression, 0.58; 95% confidence interval (CI), 0.34-0.98] and OS than the control group (p = 0.0469; HR for death, 0.56; 95% CI, 0.32-0.99). No chemotherapy-related mortality occurred. Patients of the ACT group suffered more common and severer hand-foot syndrome (HFS) (p = 0.02). CONCLUSIONS: Additional S-1 chemotherapy may be helpful for improving the disease progression and survival for patients with Stage III GC after radical resection with an acceptable safety profile.

Anthracycline-containing regimens or taxane versus S-1 as first-line chemotherapy for metastatic breast cancer.

BACKGROUND: We have previously demonstrated S-1 is non-inferior to taxane with respect to overall survival as first-line chemotherapy for HER2-negative metastatic breast cancer. We aimed to confirm whether S-1 is also non-inferior to anthracycline-containing regimens in the same setting. METHODS: We conducted an open-label, non-inferiority, Phase 3 study. Individuals who had HER2-negative metastatic breast cancer, had received no chemotherapy for advanced disease and had endocrine therapy resistance, were randomly assigned to the anthracycline-containing regimens or S-1. The primary endpoint was overall survival. A pre-planned combined analysis of our two Phase 3 studies was also carried out. RESULTS: We enrolled 230 patients (anthracycline, n = 115; S-1, n = 115). Median overall survival was 30.1 months (95% CI 24.9-35.8) with the S-1 group and 33.7 months (95% CI 25.5-36.9) with the anthracycline group. The HR for the anthracycline group was 1.09 (95% CI 0.80-1.48). The combined analysis constituted 814 patients (395 assigned to standard treatment (anthracycline or taxane); 419 assigned to S-1). Median overall survival was 36.3 months in the standard treatment group and 32.7 months in the S-1 group. S-1 was non-inferior to standard treatment in terms of overall survival (HR 1.06 (95% CI 0.90-1.25); P non-inferiority = 0.0062). CONCLUSIONS: S-1 could be considered a new treatment option for first-line chemotherapy for patients with HER2-negative metastatic breast cancer. CLINICAL TRIAL REGISTRATION: The University Hospital Medical Information Network, Japan: UMIN000005449. This trial was registered on 15 April, 2011.

Surgery alone, adjuvant tegafur/gimeracil/octeracil (S-1), or platinum-based chemotherapies for resectable gastric cancer: real-world experience and a propensity score matching analysis.

BACKGROUND: Adjuvant chemotherapy has changed the paradigm in resectable gastric cancer. S-1 is an oral chemotherapeutic with promising efficacy in Asia. However, comparisons with close observation or platinum-based doublets post D2 gastrectomy have been less reported, notably on real-world experiences. METHODS: We retrospectively evaluated patients with D2-dissected stage IB-III gastric cancer who received S-1 (S-1, n = 67), platinum-based doublets (P, n = 145) and surgery with close observation (OBS, n = 221) from Jan 2008 to Oct 2018. A propensity score matching was used to compare for recurrence-free (RFS) and overall survivals (OS) in patients who had a locally-advanced disease (T3-4 or lymph node-positive). Adverse reactions, dosage, and associated factors for S-1 are also discussed. RESULTS: In a median follow-up time of 51.9 months, adjuvant S-1 monotherapy was associated with an intermediate survival as compared with P and OBS (median RFS/OS: S-1 vs. P, 20.9/35.8 vs. 31.2/50.5 months, HR = 1.76/2.14, p = 0.021/0.008; S-1 vs. OBS, 24.4/40.2 vs. 20.7/27.0 months, HR = 0.62/0.55, p = 0.041/0.024). The survival differences were more prominent in patients with N2-3 diseases. S-1 was well-tolerated with a relative dose intensity of 73.6%, a median duration of 8.3 months and associated with less adverse reactions as compared with P. S-1 monotherapy was selected by physicians based on age, lymph node stage, serum carcinoembryonic antigen and disease stage. CONCLUSIONS: Adjuvant S-1 correlated with intermediate survival outcomes between OBS and P but conferred fewer adverse reactions as compared with P. Patients with a moderate risk of recurrence had comparable survivals when treated with S-1 while platinum-based doublets were favored in advanced cases. The study provides additional information about adjuvant S-1 in patients with selected risk of recurrence.

Short-term survival and safety of apatinib combined with oxaliplatin and S-1 in the conversion therapy of unresectable gastric cancer.

BACKGROUND: We conducted a single-arm phase II trial to investigate the short-term efficacy and safety of apatinib combined with oxaliplatin and S-1 in the treatment of unresectable gastric cancer. PATIENTS AND METHODS: Previously untreated patients with unresectable HER-2-negative advanced gastric cancer were selected. All the patients received six cycles of S-1 and oxaliplatin and five cycles of apatinib, which were administered at intervals of three weeks. The surgery was performed after six cycles of drug treatment. The primary endpoints were radical resection (R0) rate and safety. This study was registered with the China Trial Register, number ChiCTR-ONC-17010430  (01/12/2016-01/12/2022). RESULTS: A total of 39 patients were enrolled. Efficacy evaluation was feasible for 37 patients. One patient achieved complete response (CR, 2.7%), 26 patients achieved partial response (PR, 70.3%), three patients had stable disease (SD, 8.1%) and seven patients had progressive disease (PD, 18.9%). The objective response rate (ORR) was 73.0% and the disease control rate (DCR) was 81.1%. 22 patients underwent surgery, among which 14 patients underwent radical resection (R0), with a R0 resection rate of 63.6%. The 1-year survival rate of the surgical group (22 patients) was 71.1% and the 2-year survival rate was 41.1%. The median survival time was 21 months. The incidence of adverse events (AEs) was 100%. Leucopenia (65.3%) and granulocytopenia (69.2%) were the most common hematological AEs. The most common non-hematological AEs were fatigue (51.3%) and oral mucositis (35.9%). CONCLUSION: Apatinib combined with oxaliplatin and S-1 showed good short-term survival and acceptable safety in the conversion therapy of unresectable gastric cancer.

Comparison of outcomes of children with acute lymphoblastic leukemia treated with BMF protocol across 2 decades.

Acute lymphoblastic leukemia is the most common malignancy of childhood. The aim of this study is to compare the outcome of children with acute lymphoblastic leukemia treated with BFM protocol over two decades at our center. We retrospectively examined the files of 421 patients by dividing them into two groups by decade of treatment, 1995-2005 and 2006-2015. After excluding 117 patients, overall, 304 patients were included in the analysis. From the first to the second decade, the proportion of patients over 12 years of age increased from 7.1% to 16.8% (p < 0.04), the high-risk group increased from 15.5% to 19.5% and patients with central nervous system leukemia increased from 5.2% to 11.4%. The relapse rate remained relatively unchanged during this period (from 12.9% to 12.7%), while the mortality rate decreased from 18.7% to 15.4% (p > 0.05) and the death rate during remission induction treatment decreased from 3.9% to 0.7%. The mortality rate of high-risk and standard-risk patients decreased from 62.5% to 34.5% (p < 0.05) and 11.1% to 3.0% (p > 0.05), respectively. The 5-year overall survival and event-free survival rates for standard-, medium- and high-risk patients were 92.7% ± 6.0%, 87.9% ± 4.7%, and 54.7% ± 13.3% and 92.5% ± 6.3%, 83.2% ± 5.5%, and 48.7% ± 14.7%, respectively. For the cohort, the 5-year overall survival rate was 83.2% ± 4.1% and the event-free survival rate was 79.9% ± 4.7%. These results demonstrate the impact of a standard protocol, experience of staff, achieving better risk stratification on treatment success.

Human equilibrative nucleoside transporter-1 expression is a predictor in patients with resected pancreatic cancer treated with adjuvant S-1 chemotherapy.

The high expression of human equilibrative nucleoside transporter-1 (hENT1) and the low expression of dihydropyrimidine dehydrogenase (DPD) are reported to predict a favorable prognosis in patients treated with gemcitabine (GEM) and 5-fluorouracil (5FU) as the adjuvant setting, respectively. The expression of hENT1 and DPD were analyzed in patients registered in the JASPAC 01 trial, which showed a better survival of S-1 over GEM as adjuvant chemotherapy after resection for pancreatic cancer, and their possible roles for predicting treatment outcomes and selecting a chemotherapeutic agent were investigated. Intensity of hENT1 and DPD expression was categorized into no, weak, moderate or strong by immunohistochemistry staining, and the patients were classified into high (strong/moderate) and low (no/weak) groups. Specimens were available for 326 of 377 (86.5%) patients. High expression of hENT1 and DPD was detected in 100 (30.7%) and 63 (19.3%) of 326 patients, respectively. In the S-1 arm, the median overall survival (OS) with low hENT1, 58.0 months, was significantly better than that with high hENT1, 30.9 months (hazard ratio 1.75, P = 0.007). In contrast, there were no significant differences in OS between DPD low and high groups in the S-1 arm and neither the expression levels of hENT1 nor DPD revealed a relationship with treatment outcomes in the GEM arm. The present study did not show that the DPD and hENT1 are useful biomarkers for choosing S-1 or GEM as adjuvant chemotherapy. However, hENT1 expression is a significant prognostic factor for survival in the S-1 arm.

Prediction of Efficacy of Postoperative Chemotherapy by DNA Methylation of CDO1 in Gastric Cancer.

BACKGROUND: CDO1 is a presumed tumor suppressor gene in human cancers, the expression of which is silenced by promoter DNA methylation. Moreover, CDO1 harbors functionally oncogenic aspects through modification of mitochondrial membrane potential. We recently proposed that this oncogenic feature allows for the prediction of the efficacy of postoperative chemotherapy in colon cancer. The present study aims to elucidate the efficacy of prediction of success of postoperative chemotherapy in advanced gastric cancer to improve the treatment strategy of patients. MATERIALS AND METHODS: Forced expression of CDO1 in gastric cancer cell lines was assessed using the JC-1 assay. Promoter DNA methylation was investigated in quantitative TaqMan methylation-specific polymerase chain reaction in 321 pathological stage II/III advanced gastric cancer cases treated by curative gastrectomy with or without postoperative chemotherapy. RESULTS: (1) Forced expression of CDO1 led to increased mitochondrial membrane potential, accompanied by augmented survival in gastric cancer cells under anaerobic conditions. These results suggest that CDO1-expressing cancer cells survive more easily in anaerobic lesions which are inaccessible to anticancer drugs. (2) Intriguingly, in cases with the highest CDO1 methylation (ranging from 15% to 40%), patients with postoperative chemotherapy showed significantly better survival than those with no postoperative chemotherapy. (3) A robust prognostic difference was observed that was explained by differential recurrences of distant metastasis (P = 0.0031), followed by lymph node (P = 0.0142) and peritoneal dissemination (P = 0.0472). CONCLUSIONS: The oncogenic aspects of CDO1 can be of use to determine patients with gastric cancer who will likely respond to treatment of invisible systemic dissemination by postoperative adjuvant chemotherapy.

Reversible Splenial Lesion Syndrome (RESLES) After Chemotherapy of Oral Tegafur-uracil in a Female With Locally Rectal Adenocarcinoma.

A 42-year-old woman with reversible splenial lesion syndrome (RESLES) and rectal adenocarcinoma presented with sudden-onset delirium after the sixth cycle of her chemotherapy drug, oral tegafur-uracil (300 mg/m/day, days 1-14, with treatment cycle repeated every 21 days). Accompanied by the anti-CV2 antibody, paraphasia, and a loss of bimanual coordination, the patient's etiology and clinical manifestations of RESLES are unlike those of other reported cases of RESLES. Tegafur-uracil is an oral fluoropyrimidine that has a similar effect to 5-fluorouracil as an adjuvant treatment for colorectal cancer. The possibility that the toxicity of chemotherapeutic drugs may play a role in the pathogenesis of cytotoxic edema in the splenium of the corpus callosum and extracallosal white matter should be investigated further.

S-1 plus Raltitrexed for Refractory Metastatic Colorectal Cancer: A Phase II Trial.

LESSONS LEARNED: The upregulation of dihydropyrimidine dehydrogenase (DPD) and thymidylate synthase (TS) are important mechanisms of resistance to 5-fluorouracil (5-FU) in metastatic colorectal cancer (mCRC) after long exposure to 5-FU.S-1 (containing a DPD inhibitor) combined with raltitrexed (a TS inhibitor) showed a moderate effect, which needs further study as a third- or later-line therapy in mCRC. BACKGROUND: 5-fluorouracil (5-FU) is a fundamental drug in the treatment of metastatic colorectal cancer (mCRC). Patients with mCRC are often exposed to 5-FU and/or its analogues for a long time because of its central role in treatment regimens. The upregulation of dihydropyrimidine dehydrogenase (DPD) and/or thymidylate synthase (TS) are important mechanisms of resistance of 5-FU. To evaluate the efficacy and safety of S-1 (containing a DPD inhibitor) and raltitrexed (a TS inhibitor) for refractory mCRC, a one-center, single-arm, prospective phase II trial was conducted. METHODS: Patients who had mCRC that had progressed after treatment with fluoropyrimidine, irinotecan, and oxaliplatin and who had at least one measurable lesion were eligible for this trial. Patients received oral S-1 (80-120 mg for 14 days every 3 weeks) plus an intravenous infusion of raltitrexed (3 mg/m2 on day 1 every 3 weeks). The primary endpoint was objective response rate (ORR). Secondary endpoints included progression-free survival (PFS), overall survival (OS), and toxicity. RESULTS: In total, 46 patients were enrolled. Three patients did not complete the first assessment because of adverse events and unwillingness, leaving tumor response evaluation available in 43 patients. Of 43 evaluable patients, the ORR was 13.9% and disease control rate was 58.1%. In the intention-to-treat population (n = 46), the ORR was 13.0% and disease control rate was 54.3%. Median PFS and median OS were 107 days (95% confidence interval [CI], 96.3-117.7) and 373 days (95% CI, 226.2-519.8), respectively. Most of the adverse effects were mild to moderate. CONCLUSION: S-1 combined with raltitrexed for refractory mCRC showed moderate effect, and it is worthy of further study as third- or later-line therapy in mCRC.

Collagen gel droplet-embedded culture drug sensitivity test (CD-DST) predicts the effect of adjuvant chemotherapy on pancreatic cancer.

PURPOSE: We evaluated the clinical effectiveness of collagen gel droplet-embedded culture drug sensitivity tests (CD-DSTs) in predicting the efficacy of adjuvant chemo-therapeutic treatments for pancreatic cancer (PC). METHODS: The clinicopathological characteristics and prognoses of 22 PC patients who underwent CD-DST after pancreatectomy at Tohoku University between 2012 and 2016 were analyzed retrospectively. Eligibility criteria were resectable or borderline resectable PC, successful evaluation for 5-fluorouracil sensitivity by CD-DST, treatment with S-1 adjuvant chemotherapy, and no preoperative chemotherapy. RESULTS: The rate of successful evaluation by CD-DST was 52.3% in PC. The optimal T/C ratio, defined as the ratio of the number of cancer cells in the treatment group (T) to that in the control group (C), for 5-fluorouracil was 85% using receiver operating characteristic curve analysis. The sensitive group (T/C ratio < 85%; n = 11) had a better recurrence-free survival rate than the resistant group (T/C ratio ≥ 85%; n = 11; P = 0.029). A Cox proportional hazards regression model demonstrated that sensitivity to 5-fluorouracil was an independent predictor of recurrence on multivariate analysis (hazard ratio 3.28; 95.0% CI 1.20-9.84; P = 0.020). CONCLUSIONS: CD-DSTs helped to predict PC recurrence after S-1 adjuvant chemotherapy.

S-1 plus nab-paclitaxel is a promising regimen for pancreatic cancer in a preclinical model.

OBJECTIVES: The aim of this study was to investigate the efficacy and mechanism of action of combined S-1 and nab-paclitaxel in pancreatic cancer. METHODS: Three human pancreatic cancer cell lines were treated with S-1, nab-paclitaxel, alone or in combination. Mice bearing subcutaneous xenograft of the cell line, PANC-1, were treated with the same drugs. RESULTS: The growth-inhibitory effect of combined S-1 and nab-paclitaxel was greater than that of the individual drugs, and the combination index value indicated that S-1 and nab-paclitaxel had a synergistic effect in vitro. The combination of S-1 and nab-paclitaxel showed greater efficacy in vivo than monotherapy, and the growth-inhibitory effect was significantly greater when compared with the controls (P = 0.009), although no significant reduction in body weight was observed. Fractional tumor volume analysis indicated that the combination had a synergistic effect. Tumor stroma staining with α-smooth muscle actin was significantly decreased by nab-paclitaxel (P < 0.001) while the number of CD31-stained microvessel lumina was significantly increased by the combination therapy when compared with the control (P = 0.046). CONCLUSIONS: S-1 and nab-paclitaxel had a synergetic effect in preclinical studies with good tolerability, and may play a role in stromal depletion and tumor angiogenesis. J. Surg. Oncol. 2016;113:413-419. © 2016 Wiley Periodicals, Inc.

Decorin in human oral cancer: a promising predictive biomarker of S-1 neoadjuvant chemosensitivity.

We reported previously that decorin (DCN) is significantly up-regulated in chemoresistant cancer cell lines. DCN is a small leucine-rich proteoglycan that exists and functions in stromal and epithelial cells. Accumulating evidence suggests that DCN affects the biology of several types of cancer by directly/indirectly targeting the signaling molecules involved in cell growth, survival, metastasis, and angiogenesis, however, the molecular mechanisms of DCN in chemoresistance and its clinical relevance are still unknown. Here we assumed that DCN silencing cells increase chemosusceptibility to S-1, consisted of tegafur, prodrug of 5-fluorouracil. We first established DCN knockdown transfectants derived from oral cancer cells for following experiments including chemosusceptibility assay to S-1. In addition to the in vitro data, DCN knockdown zenografting tumors in nude mice demonstrate decreasing cell proliferation and increasing apoptosis with dephosphorylation of AKT after S-1 chemotherapy. We also investigated whether DCN expression predicts the clinical responses of neoadjuvant chemotherapy (NAC) using S-1 (S-1 NAC) for oral cancer patients. Immunohistochemistry data in the preoperative biopsy samples was analyzed to determine the cut-off point for status of DCN expression by receiver operating curve analysis. Interestingly, low DCN expression was observed in five (83%) of six cases with complete responses to S-1 NAC, and in one (10%) case of 10 cases with stable/progressive disease, indicating that S-1 chemosensitivity is dramatically effective in oral cancer patients with low DCN expression compared with high DCN expression. Our findings suggest that DCN is a key regulator for chemoresistant mechanisms, and is a predictive immunomarker of the response to S-1 NAC and patient prognosis.

Simvastatin enhances the chemotherapeutic efficacy of S-1 against bile duct cancer: E2F-1/TS downregulation might be the mechanism.

Simvastatin has inhibitory effects on cancers. The present study aimed to investigate the interactive effects between simvastatin and S-1 against bile duct cancer and its mechanisms. The effects of simvastatin and 5-fluorouracil (5-FU) alone or in combination on the growth and apoptosis of the human cholangiocarcinoma cell line EGI-1 and the gallbladder carcinoma cell line Mz-ChA-1 cells were evaluated in vitro. Real-time PCR and western blot were used to determine E2F-1 and thymidylate synthase (TS) expressions in the treated cells. Tumoricidal efficacy of simvastatin and S-1 was further investigated in a subcutaneous bile duct cancer model in NOD/SCID mice. Simvastatin enhanced the cytotoxicity of 5-FU on bile duct cancer cells in vitro. IC50 of 5-FU alone was 4.34 µmol/l for EGI-1 and 13.9 µmol/l for MZ-ChA-1, whereas it decreased markedly to 0.90 and 2.95 µmol/l, respectively, when combined with simvastatin. The Chou and Talalay combination index of 5-FU and simvastatin was 0.41 and 0.40 at IC50 for EGI-1 and MZ-ChA-1, respectively. Simvastatin alone or plus 5-FU significantly suppressed E2F-1 and TS expressions in EGI-1 and MZ-ChA-1. Simvastatin plus 5-FU induced greater proportion of apoptotic cells on both EGI-1 and MZ-ChA-1, with an increase in cleaved caspase-3 levels, compared with simvastatin or 5-FU alone (all P < 0.05). Simvastatin plus S-1 induced greater tumor inhibition than simvastatin or S-1 alone with E2F-1/TS downregulation in vivo (all P < 0.05). Simvastatin and S-1 exerted synergistic effects against bile duct cancer, which might be mediated by E2F-1/TS downregulation. The combination could be a reasonable regimen in the management of bile duct cancer.

Agrocybe aegerita polysaccharide combined with chemotherapy improves tumor necrosis factor-α and interferon-γ levels in rat esophageal carcinoma.

Natural compounds have generated great interest as alternative treatments of diseases like cancer. Here, we investigated the anti-tumor mechanism of one such compound, Agrocybe aegerita polysaccharide, by assessing expression of tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) in rat esophageal carcinoma (EC). EC was induced in healthy Wistar rats by methyl-n-amyl nitrosamine. Subsequently, rats were administered cancer treatment daily for 4 weeks, as follows: the normal control group (the only group not treated with methyl-n-amyl nitrosamine) and model group received only distilled water; the chemotherapy group received tegafur treatment; and the combination group received tegafur combined with A. aegerita polysaccharide. In normal and combination groups, body weight increased gradually after each week of treatment (P < 0.05), while body weights did not change in model and chemotherapy groups. Using enzyme linked immunosorbent assay, we found serum TNF-α was lower in the combination group (31.56 ± 7.20 pg/L) than either the model (46.24 ± 8.52 pg/L) or chemotherapy (52.39 ± 9.16 pg/L) group, and, while higher, was more similar to the normal controls (25.08 ± 2.93 pg/L; P < 0.05), a finding that was confirmed by the immunohistochemistry of esophageal samples. In contrast, serum IFN-γ was higher in the combination group (97.20 ± 10.92 pg/L) than in either the model (76.11 ± 11.92 pg/L) or chemotherapy (76.04 ± 9.85 pg/L) group, but lower than in the normal group (117.56 ± 10.88; P < 0.05), also confirmed by immunohistochemistry. Therefore, Agrocybe aegerita polysaccharide, when combined with chemotherapy, can regulate immune function in EC, potentially by modulating cytokine activity, specifically downregulation of TNF-α and upregulation of IFN-γ.

Low-dose docetaxel enhances the sensitivity of S-1 in a xenograft model of human castration resistant prostate cancer.

S-1 is a recently developed dihydropyrimidine dehydrogenase inhibitor fluoropyrimidine and has demonstrated high maximum plasma 5-Fluorouracil (5-FU) levels with mild toxicity, and an oral formulation has resulted in an improvement in patient quality of life. The aims of the present study were to determine the efficacy of S-1 or S-1 combined with docetaxel (DOC) using castration resistant prostate cancer (CRPC) cells and to explore their clinical potential for treating CRPC patients. LNCaP cells, androgen dependent prostate cancer (ADPC) cells and C4-2 cells, which are a CRPC subline of LNCaP cells, were used. Specimens obtained from ADPC and CRPC patients were also evaluated. The CRPC specimens and C4-2 cells exhibited significantly lower thymidylate synthase (TS) expression, a target of 5-FU, than the ADPC specimens and LNCaP cells. In vitro, C4-2 cells exhibited higher sensitivity to 5-FU than LNCaP cells. In C4-2 xenograft model, S-1 monotherapy suppressed tumor growth and low-dose DOC enhanced the anti-tumor effect of S-1. In vitro, low-dose DOC, which did not induce G2/M arrest, increased p53 and p21 and resulted in down-regulation of TS in C4-2 cells, and down-regulation of TS is considered to be responsible for the synergistic effect of S-1 in vivo. The present findings indicate that CRPC patients with androgen ablation may be good candidates for 5-FU based chemotherapy, and these regimens have attractive therapeutic potential for clinical practice, and they may have a significant impact on therapeutic options.

Effect of a combination of S-1 and gemcitabine on cell cycle regulation in pancreatic cancer cell lines.

In a previous study, we showed that a combination of an oral fluoropyrimidine anticancer agent (S-1) and gemcitabine (GEM) had synergistic effects on cell growth and cell cycle arrest in the pancreatic cancer cell line MIA PaCa-2. Therefore, we conducted further mechanistic studies using the pancreatic cancer cell lines MIA PaCa-2 and SUIT-2. The combined effect of S-1 and GEM in SUIT-2 cells was evaluated using an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and the effects of S-1, GEM and S-1 plus GEM on cell cycle regulation were assessed using flow cytometry. We also examined the expression of several cell cycle regulatory proteins in both MIA PaCa-2 and SUIT-2 cells by western blotting. Classical isobolographic analysis of the MTT assay results showed that the combination of S-1 and GEM had a synergistic effect in SUIT-2 cells, and flow cytometric analysis of the cell cycle showed that the combination of S-1 plus GEM induced S-phase arrest to a greater degree than did either S-1 or GEM alone. Also, the combination of S-1 and GEM resulted in the downregulation of cyclin D1 expression and upregulation of cyclin A, p21 and p27 expression levels. Treatment of MIA PaCa-2 and SUIT-2 cells with a combination of both drugs also led to the increased phosphorylation of checkpoint kinase 1. Combined treatment with S-1 and GEM resulted in more prolonged S-phase arrest than with either treatment alone. This difference is shown to be potentially due to the higher levels of phosphorylated checkpoint kinase 1 in pancreatic cancer cell lines treated with the two agents.

A double-modulation strategy in cancer treatment with a chemotherapeutic agent and siRNA.

5-Fluorouracil (5-FU) is broadly considered the drug of choice for treating human colorectal cancer (CRC). However, 5-FU resistance, mainly caused by the overexpression of antiapoptotic proteins such as Bcl-2, often leads ultimately to treatment failure. We here investigated the effect of Bcl-2 gene silencing, using small interfering RNA (siRNA) (siBcl-2), on the efficacy of 5-FU in CRC. Transfection of siBcl-2 by a Lipofectamine2000/siRNA lipoplex effectively downregulated Bcl-2 expression in the DLD-1 cell line (a CRC), resulting in significant cell growth inhibition in vitro upon treatment with 5-FU. For in vivo treatments, S-1, an oral formulation of Tegafur (TF), a prodrug of 5-FU, was used to mimic 5-FU infusion. The combined treatment of polyethylene glycol (PEG)-coated siBcl-2-lipoplex and S-1 showed superior tumor growth suppression in a DLD-1 xenograft model, compared to each single treatment. Surprisingly, daily S-1 treatment enhanced the accumulation of PEG-coated siBcl-2-lipoplex in tumor tissue. We propose a novel double modulation strategy in cancer treatment, in which chemotherapy enhances intratumoral siRNA delivery and the delivered siRNA enhances the chemosensitivity of tumors. Combination of siRNA-containing nanocarriers with chemotherapy may compensate for the limited delivery of siRNA to tumor tissue. In addition, such modulation strategy may be considered a promising therapeutic approach to successfully managing 5-FU-resistant tumors.

A phase I study of S-1 treatment with a 3 week schedule in advanced biliary cancer patients with or without hepatic dysfunction.

PURPOSE: A 3 week treatment schedule consisting of 2 weeks of S-1 therapy and 1 week of no therapy was introduced to reduce the toxicity and increase the convenience of combination chemotherapy. Hepatic dysfunction (HD) is common in patients with biliary tract cancer. A phase I study was conducted to assess the effects of a 3 week treatment schedule in Asian patients with or without HD. METHODS: Forty-six patients were stratified into four groups, according to the HD criteria of the National Cancer Institute Organ Dysfunction Working Group. A three dose escalation schema was used. RESULTS: In the normal hepatic function group, two dose-limiting toxicity (DLT) events occurred among 12 patients at the prespecified maximal dose of 100 mg/m²/day. This dose was thereby established as the maximal tolerable dose (MTD). No DLT events were observed at the predefined maximal dose of 80 mg/m²/day in the mild HD group. In the moderate HD group, two DLT events occurred among five patients treated with 80 mg/m²/day, and the MTD was defined as 70 mg/m²/day. Two of six subjects in the severe HD group experienced DLT events at doses of 60 mg/m²/day and none developed DLT events at 50 mg/m²/day. CONCLUSIONS: The MTDs for a 3 week schedule of S-1 treatment were defined in patients with or without hepatic dysfunction. A 3 week treatment regimen of S-1 might be a platform for combination with newer cytotoxic agents or biologics.

Predictive values of 5-fluorouracil pathway genes for S-1 treatment in patients with advanced gastric cancer.

Determination of significant associations between gene expression and predefined endpoints might improve treatment tailoring for advanced gastric cancer. We investigated the mRNA expression of 5-fluorouracil (5-FU) pathway genes in prechemotherapeutic tumor samples of primary gastric cancer to try to predict the treatment outcome of S-1 monotherapy. 5-FU pathway genes, dihydropyrimidine dehydrogenase (DPD), orotate phosphoribosyltransferase (OPRT), thymidylate synthase (TS), and thymidine phosphorylase (TP), were analyzed using quantitative real-time PCR of RNA extracted from archived formalin-fixed paraffin-embedded tissues. We selected the median value for each gene as a cutoff to separate patients into high and low gene expression groups. High OPRT gene expression was significantly associated with tumor response (P = 0.014). In a combined analysis including OPRT, patients with high OPRT and TP showed a higher overall response rate than did the remaining patients (40 vs. 10%, respectively; P = 0.002). For survival, patients with high OPRT and low TS levels showed prolonged survival in both progression-free survival (3.4 vs. 2.4 months, P = 0.024) and overall survival (11.0 vs. 8.2 months, P = 0.007). In a multivariate analysis, the combinations of OPRT and TP for response and OPRT and TS for both progression-free survival and overall survival were independent variables. To conclude, mRNA expression levels of molecular markers in formalin-fixed paraffin-embedded specimens of primary gastric tumors can be useful for identifying patients with advanced gastric cancer who would most likely benefit from S-1 treatment.

Individual differences in prothrombin time-international normalized ratio variation following coadministration of the anticancer agents S-1 and warfarin: 3 case reports.

OBJECTIVE: We report three cases of elevated prothrombin time-international normalized ratios (PT-INR) following the initiation of coadministration of warfarin and S-1, a preparation containing tegafur (FT), gimeracil (CDHP), and oteracil potassium (Oxo). CASE SUMMARIES: The three cases included 2 men and 1 woman aged 79, 71, and 54 y, respectively. PT-INRs were in the range of 2.0 - 3.0 before therapy but were elevated to values in the range of 3.79 - 4.92 within 8 - 17 days after initiating the coadministration of warfarin (1.5 - 3.5 mg/d) and S-1 (80 - 120 mg/d). When the drug interactions in Cases 1 - 3 were evaluated using the Drug Interaction Probability Scale, each of these cases was assessed as "probable". DISCUSSION: The drug interaction between warfarin and S-1 presumably leads to elevated PT-INR because the 5-fluorouracil (5-FU), which is metabolite of FT in S-1, inhibits the metabolic processing of S-warfarin by cytochrome P450 (CYP) 2C9. However, individual differences in the metabolic production of 5-FU from FT because of genetic polymorphisms in CYP2A6 and individual variation in the levels of renal function may lead to complications when 5-FU is coadministered with warfarin as compared to when 5-FU is administered alone. CONCLUSION: It is essential that the dosage level of warfarin is appropriately adjusted by frequent PT-INR measurements when warfarin and S-1 are coadministered.