Prospective evaluation and refinement of an S-1 dosage formula based on renal function for clinical application.

In patients with impaired renal function, S-1-related toxicities increase due to higher exposure of 5-fluorouracil (5-FU). Our previous pharmacokinetic study in 16 cancer patients with various renal functions developed an S-1 dosage formula based on individual creatinine clearance (CLcr) and body surface area (BSA). To evaluate and refine the formula, this prospective study was conducted. Thirty-three patients with various renal functions received S-1 for 4 weeks at doses determined by the nomogram derived from the previously developed formula. A series of blood samples were collected after the first dose to calculate the area under the concentration-time curve (AUC) of 5-FU. Thirty patients with BSA of 1.14-1.84 m2 and CLcr of 23.8-96.4 mL/min were assessable for pharmacokinetics. The observed daily AUC ranged from 712.6 to 2868.7 ng·h/mL, and 18 patients achieved the target AUC (1447.8 ± 545.4 ng·h/mL). Three patients experienced S-1-related grade 3 adverse events during the first course. In the population pharmacokinetic analysis from the combined data of 46 patients in this study and the previous study, sex was identified as a statistically significant covariate for 5-FU clearance. Hence, the refined formula includes sex as an additional factor: Recommended daily dose = target AUC × (14.5 + 8.23 × SEX [0 for female and 1 for male] + 0.301 × CLcr) × BSA. Revised nomograms for recommended daily doses derived from the refined formula can be used in clinical practice to achieve the target AUC ensuring efficacy and safety of S-1.

Neutralization of Acidic Tumor Microenvironment (TME) with Daily Oral Dosing of Sodium Potassium Citrate (K/Na Citrate) Increases Therapeutic Effect of Anti-cancer Agent in Pancreatic Cancer Xenograft Mice Model.

Extracellular pH (pHe) of tumor cells is characteristic of tumor microenvironment (TME). Acidic TME impairs the responses of tumors to some anti-cancer chemotherapies. In this study, we showed that daily oral dosing of sodium potassium citrate (K/Na citrate) increased blood HCO3- concentrations, corresponding to increase of HCO3- concentrations and pHs in urine, and neutralized the tumor pHe. Neutralization of acidic TME by alkaline substance like HCO3-, an active metabolite of K/Na citrate, well potentiated the therapeutic effect of anticancer agent TS-1®, an orally active 5-fuluoro-uracil derivative, in Panc-1 pancreatic cancer-xenograft murine model. Neutralization of acidic TME by using an alkaline K/Na citrate is a smart approach for enhancement of the therapeutic effects of anticancer agents for pancreatic cancer in the end stage.

Pharmacokinetic study of the oral fluorouracil antitumor agent S-1 in patients with impaired renal function.

Although dose reduction of S-1 is recommended for patients with impaired renal function, dose modification for such patients has not been prospectively evaluated. The aim of the present study was to investigate the pharmacokinetic parameters of 5-fluorouracil, 5-chloro-2,4 dihydroxypyridine and oteracil potassium, and to review the recommended dose modification of S-1 in patients with renal impairment. We classified patients receiving S-1 into 4 groups according to their renal function, as measured using the Japanese estimated glomerular filtration rate (eGFR) equation. The daily S-1 dose was adjusted based on the patient's eGFR and body surface area. Blood samples were collected for pharmacokinetic analysis. A total of 33 patients were enrolled and classified into 4 groups as follows: 10 patients in cohort 1 (eGFR ≥ 80 mL/min/1.73 m2 ), 10 patients in cohort 2 (eGFR = 50-79 mL/min/1.73 m2 ), 10 patients in cohort 3 (eGFR = 30-49 mL/min/1.73 m2 ), and 3 patients in cohort 4 (eGFR < 30 mL/min/1.73 m2 ). Those in cohorts 3 and 4 treated with an adjusted dose of S-1 showed a similar area under the curve for 5-fluorouracil (941.9 ± 275.6 and 1043.5 ± 224.8 ng/mL, respectively) compared with cohort 2 (1034.9 ± 414.3 ng/mL). Notably, while there was a statistically significant difference between cohort 1 (689.6 ± 208.8 ng/mL) and 2 (P = 0.0474) treated with an equal dose of S-1, there was no significant difference observed in the toxicity profiles of the cohorts. In conclusion, dose adjustment of S-1 in patients with impaired renal function using eGFR is appropriate and safe.

First-in-human phase 1 study of novel dUTPase inhibitor TAS-114 in combination with S-1 in Japanese patients with advanced solid tumors.

Background This first-in-human phase 1 study assessed the safety of TAS-114, a novel deoxyuridine triphosphatase inhibitor, combined with S-1 to determine its maximum tolerated dose (MTD) and recommended dose (RD). Methods In this dose-escalation study with a 3 + 3 design, TAS-114 and S-1 were concurrently administered orally under fasting conditions at 5-240 mg/m2 and 30-36 mg/m2, respectively, in patients with advanced solid tumors. Safety, efficacy, and pharmacokinetics (PK) were evaluated. Results Seventy-six patients were enrolled. The MTD and RD were TAS-114 200 mg/m2 plus S-1 36 mg/m2 and TAS-114 240 mg/m2 plus S-1 30 mg/m2, respectively. Common treatment-related adverse events were anemia, lymphocytopenia, leukopenia, neutropenia, decreased appetite, rash, nausea, and pigmentation disorder. Partial response (PR) was observed in 10 patients (non-small cell lung cancer [NSCLC], n = 5; pancreatic neuroendocrine tumor, n = 2; gastric cancer, n = 2; gallbladder cancer, n = 1). Of these, four patients achieved PR despite prior treatment history with S-1. Patients administered TAS-114 exhibited linear PK and CYP3A4 induction, with no effect on the PK of S-1. Conclusion TAS-114 plus S-1 showed tolerable, safe, and potentially effective results. To confirm safety and efficacy, two phase 2 studies are ongoing in NSCLC and gastric cancer patients. Clinical trial registration ClinicalTrials.gov ( NCT01610479 ) .

Pharmacokinetics of S-1 monotherapy in plasma and in tears for gastric cancer patients.

BACKGROUND: S-1 is an oral anticancer drug composed of tegafur (FT), which is a prodrug of 5-FU, 5-chloro-2,4-dihydroxypyridine (CDHP), and potassium oxonate. Recently, some studies have been reported on watering eyes caused by S-1. However, the mechanism of watering eyes caused by S-1 is still unclear. The aim of this study was to investigate the correlation between tears and plasma concentrations of FT, 5-FU, and CDHP, which are components and active modulator of S-1. METHODS: We prospectively investigated the pharmacokinetics (PK) of FT, 5-FU, and CDHP in plasma and in tears of gastric cancer patients who were treated with S-1 monotherapy at the dose of 80 mg/m2/day. Plasma and tears from both eyes were obtained 1, 2, 4, and 8 h after S-1 administration on day 1 and 14 of the first cycle. RESULTS: Total of eight patients were enrolled. All the FT, 5-FU and CDHP were detected both in plasma and in tears, and their PK parameters were measured. There was a positive correlation between the concentrations of FT, 5-FU and CDHP in the plasma and those in the tears on day 1 and day 14 (correlation coefficients r, right eye/left eye: r = 0.882/0.878, 0.877/0.890, and 0.885/0.878, respectively). CONCLUSION: There was a positive correlation between the concentrations of FT, 5-FU and CDHP in the plasma and those in the tears. The result is expected to facilitate the further investigation into the causes of watering eyes and the establishment of the effective methods for the prevention and the treatment.

Phase II study of S-1 plus leucovorin in patients with metastatic colorectal cancer: Regimen of 1 week on, 1 week off.

A phase II study of S-1 plus leucovorin (LV) given in a 4-week schedule (2 weeks' administration followed by 2 weeks' rest) for patients with untreated metastatic colorectal cancer (mCRC) showed that the combination was effective, but grade 3 toxicities (diarrhea, stomatitis and anorexia) occurred at a relatively high rate. In this phase II study, we evaluated the efficacy and safety of a 2-week schedule of S-1 plus LV. Patients with mCRC received oral S-1 (40-60 mg) and LV (25 mg) twice daily for 1 week, followed by 1 week's rest. Treatment was repeated until disease progression or unacceptable toxicity. The primary endpoint was response rate. The pharmacokinetics of S-1 and LV in Chinese patients were evaluated on day 1 of the first cycle. Seventy-three patients were enrolled in Japan and China. Of 71 eligible patients, the response rate was 53.5%, and the disease control rate was 83.1%. Median progression-free survival and median overall survival were 6.5 and 24.3 months, respectively. The incidences of grade 3 toxicities were diarrhea 8.3%, stomatitis 8.3%, anorexia 2.8% and neutropenia 9.7%. There were no treatment-related deaths. The pharmacokinetics profiles of S-1 plus LV in Chinese patients were similar to those in Japanese patients. This 2-week schedule of S-1 plus LV showed good efficacy and better tolerability than the 4-week schedule. This therapy will be the base regimen for mCRC to be added by other cytotoxic or molecular-targeted drugs. The optimized treatment schedule for S-1 plus LV was 1 week on and 1 week off.

Pharmacokinetics of initial full and subsequent reduced doses of S-1 in patients with locally advanced head and neck cancer-effect of renal insufficiency.

BACKGROUND: S-1 is a combination of tegafur [metabolized to 5-fluorouracil (5-FU)] with the modulators gimeracil (5-chloro-2,4-dihydroxypyridine) and oteracil potassium. 5-Chloro-2,4-dihydroxypyridine maintains plasma 5-FU concentrations by inhibiting dihydropyrimidine dehydrogenase, a pyrimidine catabolism enzyme that degrades 5-FU. As 50% of 5-chloro-2,4-dihydroxypyridine is excreted in urine, renal insufficiency may increase its blood level, increasing 5-FU concentrations. We investigated whether special dose modification is needed in the presence of renal insufficiency. OBJECTIVE: We compared steady state pharmacokinetics of 5-FU for the initial S-1 dose and reduced doses in patients with head and neck cancer requiring dose reduction due to renal and non-renal toxicities. METHODS: Chemoradiotherapy with S-1 and cisplatin was administered every 5 weeks for two courses with a radiation dose totaling 70 Gy over 33-35 fractions. Two additional courses of adjuvant chemotherapy were administered in the case of an objective response. The S-1 and/or cisplatin dose was reduced in response to renal, hematologic or other toxicities. The primary endpoint was the change in area under the plasma concentration-versus-time curve from time 0-10 hours (5-FU AUCss 0-10) between the initial and reduced S-1 doses. RESULTS: Although the mean 5-FU levels in patients with non-renal toxicities significantly decreased between the full and reduced dose, the full-dose and reduced-dose mean maximum 5-FU plasma concentrations at steady state (Css max) and AUCss 0-10 in patients with renal insufficiency were similar. CONCLUSIONS: Standard S-1 dose reduction for renal toxicity did not result in a significant decrease in 5-FU levels at steady state. A greater reduction to lower plasma 5-chloro-2,4-dihydroxypyridine may be necessary in patients with renal insufficiency.

Effect of Sipjeondaebo-Tang on the Pharmacokinetics of S-1, an Anticancer Agent, in Rats Evaluated by Population Pharmacokinetic Modeling.

S-1 (TS-1®) is an oral fluoropyrimidine anticancer agent containing tegafur, oteracil, and gimeracil. Sipjeondaebo-tang (SDT) is a traditional oriental herbal medicine that has potential to alleviate chemotherapy-related adverse effects. The aim of the present study was to evaluate the effect of SDT on the pharmacokinetics of S-1. Sprague-Dawley rats were pretreated with a single dose or repeated doses of SDT for seven consecutive days (1200 mg/kg/day). After the completion of pretreatment with SDT, S-1 was orally administered and plasma concentrations of tegafur, its active metabolite 5-FU, and gimeracil were determined by liquid chromatography-tandem mass spectrometry (LC/MS/MS). A population pharmacokinetic model was developed to evaluate the effect of SDT on pharmacokinetics of tegafur and 5-FU. Although a single dose of SDT did not have any significant effect, the absorption rate of tegafur decreased, and the plasma levels of 5-FU reduced significantly in rats pretreated with SDT for seven days in parallel to the decreased gimeracil concentrations. Population pharmacokinetic modeling also showed the enhanced elimination of 5-FU in the SDT-pretreated group. Repeated doses of SDT may inhibit the absorption of gimeracil, an inhibitor of 5-FU metabolism, resulting in enhanced elimination of 5-FU and decrease its plasma level.

Development of an S-1 dosage formula based on renal function by a prospective pharmacokinetic study.

BACKGROUND: S-1 is an oral anticancer drug, containing tegafur (a prodrug of 5-fluorouracil, 5-FU), 5-chloro-2,4-dihydroxypyridine, and potassium oxonate. As renal dysfunction is known to increase exposure of 5-FU following S-1 administration, the incidence of severe adverse reactions is increased in patients with impaired renal function. However, no reliable information on its dose modification for patients with renal dysfunction has been provided. METHODS: We conducted a prospective pharmacokinetic study to develop an S-1 dosage formula based on renal function. Sixteen cancer patients with various degrees of renal function received a single dose of S-1 at 40 mg/m(2). A series of blood samples were collected at predefined times within 24 h to assess the plasma concentration profiles of 5-FU, 5-chloro-2,4-dihydroxypyridine, and tegafur. A mathematical model for the relationship between renal function and exposure of 5-FU was constructed by a population pharmacokinetic analysis. RESULTS: The clearance of 5-FU following S-1 administration was related to body surface area and creatinine clearance in the range 15.9-108.8 mL/min as estimated by the Cockcroft-Gault equation. The S-1 dosage formula was derived as follows:[Formula: see text]where AUC is the area under the concentration-time curve, CLcr is creatinine clearance, and BSA is body surface area. The recommended daily doses of S-1 in Asia and Europe were also proposed as nomograms according to exposure matching to the previously reported area under the concentration-time curve of 5-FU, which confirmed the efficacy and toxicity in pivotal registration studies. CONCLUSIONS: We have developed a novel formula for determining the S-1 dosage on the basis of renal function. Further validation is needed to confirm the formula for practical application.

Phase I study of weekly nab-paclitaxel combined with S-1 in patients with human epidermal growth factor receptor type 2-negative metastatic breast cancer.

We conducted a phase I study of a weekly nab-paclitaxel and S-1 combination therapy in patients with human epidermal growth factor receptor type 2-negative metastatic breast cancer. The primary objective was to estimate the maximum tolerated and recommended doses. Each treatment was repeated every 21 days. Levels 1, 2a, 2b, and 3 were set depending on the S-1 dose (65 or 80 mg/m(2) ) and nab-paclitaxel infusion schedule (days 1 and 8 or days 1, 8, and 15). Fifteen patients were enrolled. Dose-limiting toxicity was observed in one patient at Level 3 (100 mg/m(2) nab-paclitaxel on days 1, 8, and 15 with 80 mg/m(2) S-1 daily for 14 days, followed by 7 days of rest). Although the maximum tolerated dose was not reached, the recommended dose was determined to be Level 3. Neutropenia was the most frequent grade 3-4 treatment-related adverse event. For patients with measurable lesions, the response rate was 50.0% and the median time to treatment failure and median progression-free survival was 13.2 and 21.0 months, respectively. The present results show the feasibility and potential for long-term administration of this combination therapy.

A phase I dose-escalation study of eribulin and S-1 for metastatic breast cancer.

BACKGROUND: We evaluated the safety, maximum-tolerated dose (MTD), pharmacokinetics, recommended dose for phase II (P2RD), and preliminary anticancer activity of a combination eribulin and S-1 therapeutic in metastatic breast cancer patients pretreated with anthracycline and taxane. METHOD: Patients aged 20-74 years were recruited. In level 1, patients received S-1 (65 mg m(-2)) from day 1 to 14, and eribulin (1.1 mg m(-2)) on day 1 and 8 in a 21-day cycle. In level 2, eribulin was increased to 1.4 mg m(-2). In level 3, S-1 was increased to 80 mg m(-2). RESULTS: Twelve patients were enrolled into three cohorts. Planned dose escalation was completed, with one case exhibiting dose-limiting toxicity (grade 3 hypokalaemia) at level 3, without reaching the MTD. The P2RD was determined to be level 2 (eribulin 1.4 mg m(-2) and S-1 65 mg m(-2)). The most common grade 3 or 4 toxicity was neutropenia (83.3%), followed by febrile neutropenia (25.0%). Five of eleven patients (41.7%) with measurable disease had a partial response. Pharmacokinetics were characterised by dose-dependent elimination and nonlinear exposure. CONCLUSION: Dose level 3 was not tolerated owing to febrile neutropenia development. Thus, intermediate dose level 2 was recommended for further evaluation. Preliminary antitumour activity warrants further investigation in this setting.

Phase I study of sunitinib plus S-1 and cisplatin in Japanese patients with advanced or metastatic gastric cancer.

BACKGROUND: This phase I, dose-finding study evaluated the maximum tolerated dose (MTD), safety, pharmacokinetics, and antitumor activity of sunitinib plus S-1/cisplatin in Japanese patients with advanced/metastatic gastric cancer. PATIENTS AND METHODS: Patients received oral sunitinib on a continuous daily dosing (CDD) or 2-weeks-on/2-weeks-off schedule (Schedule 2/2; 25 mg/day or 37.5 mg/day), plus S-1 (80-120 mg/day)/cisplatin 60 mg/m(2). RESULTS: Twenty-seven patients received treatment, including 26 patients treated per protocol (sunitinib 25 mg/day CDD schedule, n = 4; sunitinib 25 mg/day Schedule 2/2, n = 16 [dose-limiting toxicity (DLT) cohort, n = 6 plus expansion cohort, n = 10]; sunitinib 37.5 mg/day Schedule 2/2, n = 6). One patient erroneously self-administered sunitinib 12.5 mg/day and was excluded from the analyses. The MTD was sunitinib 25 mg/day on Schedule 2/2. DLTs were reported for: 2/4 patients given sunitinib 25 mg/day on the CDD schedule; 1/6 patients administered sunitinib 25 mg/day on Schedule 2/2 (grade [G] 3 neutropenic infection, G4 thrombocytopenia, and S-1 dose interruption ≥5 days), and 3/6 patients given sunitinib 37.5 mg/day on Schedule 2/2. Results below are for the overall MTD cohort (n = 16). The most frequently reported G3/4 adverse events were neutropenia (93.8 %) and leukopenia (75.0 %). The objective response rate was 37.5 %; six additional patients experienced no disease progression for ≥24 weeks. Median progression-free survival was 12.5 months. No pharmacokinetic drug-drug interactions were observed between sunitinib/S-1/cisplatin and S-1/cisplatin. CONCLUSIONS: The MTD of sunitinib was 25 mg/day on Schedule 2/2 combined with cisplatin/S-1 in patients with advanced/metastatic gastric cancer. This regimen had a manageable safety profile and preliminary antitumor activity.

Phase I study on the safety, pharmacokinetic profile, and efficacy of the combination of TSU-68, an oral antiangiogenic agent, and S-1 in patients with advanced hepatocellular carcinoma.

PURPOSE: We aimed to investigate the recommended dose for the combination of TSU-68, a multiple-receptor tyrosine kinase inhibitor targeting vascular endothelial growth factor receptor-2 and platelet-derived growth factor receptor-ß, and S-1, an oral fluoropyrimidine, in patients with advanced hepatocellular carcinoma (HCC) based on its associated dose-limiting toxicity (DLT) frequency. We also determined the safety, tolerability, pharmacokinetics (PK), and efficacy of the combination treatment. PATIENTS AND METHODS: Patients without any prior systemic therapy received 400 mg/day TSU-68 orally and 80 mg/day (level 1) or 100 mg/day (level 2) S-1 for 4 or 2 weeks followed by a 2- or 1-week rest period (groups A and B, respectively). According to the treatment, patients progressed from level 1B to level 2A, then level 2B. Safety and response rates were assessed. RESULTS: Eighteen patients were enrolled. Two patients at levels 1B and 2A but none at level 2B showed DLTs. The common adverse drug reactions were a decrease in hemoglobin levels, hypoalbuminemia, and anorexia, which were mild in severity (grades 1-2). PK data from levels 1B and 2A indicated that the area under the curve for TSU-68 and 5-fluorouracil was unlikely to be affected by the combination treatment. Response rate, disease control rate, median time to progression, and median overall survival were 27.8 %, 61.1 %, 5.3 months, and 12.8 months, respectively. CONCLUSION: The recommended dose for advanced HCC should be 400 mg/day TSU-68 and 100 mg/day S-1 for 4 weeks followed by 2-week rest.

A phase I study of sorafenib in combination with S-1 plus cisplatin in patients with advanced gastric cancer.

BACKGROUND: Sorafenib inhibits several receptor tyrosine kinases involved in tumor progression and angiogenesis. S-1, an oral fluorouracil antitumor drug, plus cisplatin (CDDP) is the standard regimen for advanced gastric adenocarcinoma (AGC) in Japan. The purpose of this phase I study was to evaluate the safety, pharmacokinetics, and preliminary efficacy of sorafenib in combination with S-1 plus CDDP. METHODS: Patients with histologically confirmed previously untreated AGC were evaluated for eligibility and treated with sorafenib (400 mg bid, days 1-35), S-1 (40 mg/m(2) bid, days 1-21), and CDDP (60 mg/m(2), day 8). Treatment was continued until disease progression or unacceptable toxicity. Pharmacokinetics for sorafenib, 5-FU, and CDDP were investigated in cycle 1. RESULTS: Thirteen patients were enrolled and received at least one dose of the study treatment. No specific or serious adverse event was newly reported in this study. Five patients had partial response and 8 had stable disease as the best response. Pharmacokinetic analysis showed no significant differences in the exposures of sorafenib when administered alone or in combination with S-1 and CDDP. CONCLUSIONS: The present phase I study demonstrates the acceptable toxicity and preliminary efficacy of combined treatment with S-1, CDDP, and sorafenib.

Feasibility and pharmacokinetics of combined therapy with S-1 and trastuzumab in patients with human epidermal growth factor receptor 2-positive metastatic or recurrent breast cancer.

BACKGROUND: To clarify the tolerance and pharmacokinetics of combined therapy with S-1 and trastuzumab in patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic or recurrent breast cancer. METHODS: From January 2008 through to September 2009, combined therapy with S-1 and trastuzumab was given to 7 patients with HER2-positive metastatic or recurrent breast cancer. The incidence of adverse events and the pharmacokinetics of tegafur, 5-fluorouracil, and gimeracil in plasma were studied. RESULTS: One patient had grade 3 leukopenia, and another had a grade 3 elevation of alanine aminotransferase. All other adverse events were grade 2 or lower. The combination of S-1 and trastuzumab did not cause any new adverse events. The incidence of adverse events was similar to those associated with S-1 alone. The median number of treatment cycles was 11. The pharmacokinetics of tegafur, 5-fluorouracil, and gimeracil after treatment with S-1 plus trastuzumab did not markedly differ from those after S-1 alone. CONCLUSIONS: Combined therapy with S-1 and trastuzumab did not cause any new adverse events, administration continuity was good, and the therapy was well tolerated.

[Pharmacogenomics of the first-line treatment for gastric cancer: advances in the identification of genomic biomarkers for clinical response to chemotherapy]. / Farmacogenómica del tratamiento de primera linea en el cáncer gástrico: avances en la identificación de los biomarcadores genómicos de respuesta clínica.

Gastric cancer (GC) is often diagnosed at later stages due to the lack of specificity of symptoms associated with the neoplasm, causing high mortality rates worldwide. The first line of adjuvant and neoadjuvant treatment includes cytotoxic fluoropyrimidines and platin-containing compounds which cause the formation of DNA adducts. The clinical outcome with these antineoplastic agents depends mainly on tumor sensitivity, which is conditioned by the expression level of the drug targets and the DNA-repair system enzymes. In addition, some germ line polymorphisms, in genes linked to drug metabolism and response to chemotherapy, have been associated with poor responses and the development of adverse effects, even with fatal outcomes in GC patients. The identification of genomic biomarkers, such as individual gene polymorphisms or differential expression patterns of specific genes, in a patient-by-patient context with potential clinical application is the main focus of current pharmacogenomic research, which aims at developing a rational and personalized therapy (i.e., a therapy that ensures maximum efficacy with no predictable side effects). However, because of the future application of genomic technologies in the clinical setting, it is necessary to establish the prognostic value of these genomic biomarkers with genotype-phenotype association studies and to evaluate their prevalence in the population under treatment. These issues are important for their cost-effectiveness evaluation, which determines the feasibility of using these medical genomic research products for GC treatment in the clinical setting.

Randomised phase II study of S-1/cisplatin plus TSU-68 vs S-1/cisplatin in patients with advanced gastric cancer.

BACKGROUND: This study aimed to determine whether combination S-1 plus cisplatin (CDDP) therapy, the most widely used therapy for Japanese patients with advanced gastric cancer, and the novel oral antiangiogenic agent TSU-68 could contribute to gastric cancer treatment. METHODS: Ninety-three patients with chemotherapy-naïve unresectable or recurrent advanced gastric cancers were randomised into two groups: TSU-68 plus S-1/CDDP (group A) and S-1/CDDP (group B) groups. Both patient groups received identical S-1 and CDDP dosages. TSU-68 was orally administered for 35 consecutive days. Group B patients received S-1 orally twice daily for three consecutive weeks, followed by intravenous CDDP on day 8. The primary endpoint was progression-free survival (PFS). RESULTS: Median PFS periods were 208 and 213 days in groups A and B, respectively (P=0.427). Median survival periods for groups A and B were 497.0 and 463.5 days, respectively (P=0.219). No statistically significant differences were noted for PFS, survival or the adverse event (AE) incidence rate. All AEs were expected according to previous reports for TSU-68, TS-1, and CDDP. CONCLUSION: Combination therapy involving TSU-68, S-1, and CDDP was safe and well tolerated in patients with chemotherapy-naïve unresectable or recurrent advanced gastric cancers. However, factors related to therapeutic efficacy should be investigated further.

Pharmacokinetic evaluation of novel oral fluorouracil antitumor drug S-1 in Chinese cancer patients.

AIM: S-1 is an oral anticancer fluoropyrimidine formulation consisting of tegafur, 5-chloro-2,4-dihydroxypyridine and potassium oxonate. The aim of this study was to evaluate the pharmacokinetics and bioequivalence of a newly developed generic formulation of S-1 in Chinese cancer patients in comparison with the branded reference formulation of S-1. METHODS: A single-dose, randomized-sequence, open-label, two-way self-crossover study was conducted in 30 Chinese cancer patients. The subjects alternatively received the two formulations (40 mg/m(2), po) with a 7-d interval. Plasma concentrations of FT, CDHP, Oxo, and 5-Fu were determined using LC-MS/MS. Pharmacokinetic parameters, including Cmax, Tmax, t1/2, AUC0-t, and AUC0-∞ were determined using non-compartmental models with DAS2.0 software. Bioequivalence of the two formulations were to be evaluated according to 90% CIs for the log-transformed ratios of AUC and Cmax of S-1. Adverse events were evaluated through monitoring the symptom, physical and laboratory examinations, ECGs and subject interviews. RESULTS: The mean values of Cmax, AUC0-t, and AUC0-∞ of FT, 5-Fu, CDHP, and Oxo for the two formulations had no significant differences. The 90% CIs for natural log-transformed ratios of Cmax, AUC0-t, and AUC0-∞ were within the predetermined bioequivalence acceptance limits. A total of 11 mild adverse events, including fatigue, nausea and vomiting, anorexia, diarrhea and myelosuppression, were observed, and no serious and special adverse events were found. CONCLUSION: The newly developed generic formulation and reference formulation of S-1 have similar pharmacokinetics with one dose (40 mg/m(2)) in Chinese cancer patients. Both the formulations of S-1 are well tolerated.

Phase 1 trial of S-1 in combination with sorafenib for patients with advanced hepatocellular carcinoma.

PURPOSE: Sorafenib is a multi-kinase inhibitor, which was approved as first-line treatment for patients with advanced hepatocellular carcinoma (HCC). We conducted a phase 1 study of sorafenib plus S-1 in patients with advanced HCC. EXPERIMENTAL DESIGN: We designed to escalate S-1 at 4 different dose levels with fixed dose of sorafenib. Four dose levels were as follows: level 1, D1-14 S-1 50 mg/m(2)/day + D1-21 sorafenib 400 mg bid; level 2, D1-14 S-1 60 mg/m(2)/day + D1-21 sorafenib 400 mg bid; level 3,, D1-14 S-1 70 mg/m(2)/day + D1-21 sorafenib 400 mg bid; level 4, D1-14 S-1 80 mg/m(2)/day + D1-21 sorafenib 400 mg bid. The treatment was repeated every 3 weeks. RESULTS: From August 2009 to July 2010, 20 patients with advanced HCC were enrolled. The median age was 48 years (range, 29-74). Eighteen (90%) patients had hepatitis B viral infection and 19 (95%) patients were rated as Child-Pugh class A. The dose-limiting toxicities were grade 4 infection and thrombocytopenia. After a median follow-up duration of 8.6 months (range, 3.7-14.2 months), median PFS was 3.9 months (95% CI, 0.8-7.0 months) and median OS was 10.4 months (95% CI, 0-22.4 months). In pharmacokinetic analysis, there was no statistically significant drug interaction between sorafenib and S-1. CONCLUSIONS: The combination of sorafenib and S-1 showed tolerable toxicity profile and modest clinical efficacy in patients with advanced HCC. The recommended dose of sorafenib and S-1 was 400 mg twice daily and 40 mg/m(2) twice daily, respectively.

Pharmacokinetic study of S-1 in patients in whom inulin clearance was measured.

OBJECTIVE: This pharmacokinetic study of S-1 was conducted in patients in whom glomerular filtration rate (GFR) was directly measured to explore the possibility of adjusting the S-1 dose on the basis of GFR in patients with normal or nearly normal renal function. METHODS: S-1 was given to 12 patients twice daily for 28 consecutive days followed by 14 days of rest, repeated every 6 weeks. GFR was measured on the basis of inulin clearance (CLin) before the first day of treatment. RESULTS: The area under the time-concentration curve (AUC) of 5-fluorouracil (5-FU) correlated with that of 5-chloro-2,4-dihydroxypyridine (CDHP, r = 0.750, p = 0.005). The AUC of CDHP correlated with the measured 24-hour creatinine clearance (CLcr) per subject (r = -0.620, p = 0.032), but not with the CLin (r = -0.356, p = 0.257). The AUC of 5-FU did not correlate with either the 24-hour CLcr per subject (r = -0.401, p = 0.187) or with the CLin (r = -0.300, p = 0.351). CONCLUSION: Dosage adjustment based on the GFR does not reduce individual variations in 5-FU concentrations among patients with normal or nearly normal renal function who receive S-1.