Chronomodulated administration of oxaliplatin plus capecitabine (XELOX) as first line chemotherapy in advanced colorectal cancer patients: phase II study

Targeting PI3K/AKT/mTOR and MAPK Signaling Pathways in Gastric Cancer

Gastric cancer (GC) is the fourth leading cause of death worldwide, with more than 1 million cases diagnosed every year. Helicobacter pylori represents the main risk factor, being responsible for 78% of the cases. Increased amounts of salt, pickled food, red meat, alcohol, smoked food, and refined sugars negatively affect the stomach wall, contributing to GC development. Several gene mutations, including PIK3CA, TP53, ARID1A, CDH1, Ras, Raf, and ERBB3 are encountered in GC pathogenesis, leading to phosphatidylinositol 3-kinase (PI3K) protein kinase B (AKT)/mammalian target of rapamycin (mTOR)-PI3K/AKT/mTOR-and mitogen-activated protein kinase (MAPK) signaling pathway activation and promoting tumoral activity. Helicobacter pylori, growth factors, cytokines, hormones, and oxidative stress also activate both pathways, enhancing GC development. In clinical trials, promising results have come from monoclonal antibodies such as trastuzumab and ramucirumab. Dual inhibitors targeting the PI3K/AKT/mTOR and MAPK signaling pathways were used in vitro studies, also with promising results. The main aim of this review is to present GC incidence and risk factors and the dysregulations of the two protein kinase complexes together with their specific inhibitors.

Diurnal Changes in Capecitabine Clock-Controlled Metabolism Enzymes Are Responsible for Its Pharmacokinetics in Male Mice

The circadian timing system controls absorption, distribution, metabolism, and elimination processes of drug pharmacokinetics over a 24-h period. Exposure of target tissues to the active form of the drug and cytotoxicity display variations depending on the chronopharmacokinetics. For anticancer drugs with narrow therapeutic ranges and dose-limiting side effects, it is particularly important to know the temporal changes in pharmacokinetics. A previous study indicated that pharmacokinetic profile of capecitabine was different depending on dosing time in rat. However, it is not known how such difference is attributed with respect to diurnal rhythm. Therefore, in this study, we evaluated capecitabine-metabolizing enzymes in a diurnal rhythm-dependent manner. To this end, C57BL/6J male mice were orally treated with 500 mg/kg capecitabine at ZT1, ZT7, ZT13, or ZT19. We then determined pharmacokinetics of capecitabine and its metabolites, 5'-deoxy-5-fluorocytidine (5'DFCR), 5'-deoxy-5-fluorouridine (5'DFUR), 5-fluorouracil (5-FU), in plasma and liver. Results revealed that plasma C_max and AUC_0-6h (area under the plasma concentration-time curve from 0 to 6 h) values of capecitabine, 5'DFUR, and 5-FU were higher during the rest phase (ZT1 and ZT7) than the activity phase (ZT13 and ZT19) (p < 0.05). Similarly, C_max and AUC_0-6h values of 5'DFUR and 5-FU in liver were higher during the rest phase than activity phase (p < 0.05), while there was no significant difference in liver concentrations of capecitabine and 5'DFCR. We determined the level of the enzymes responsible for the conversion of capecitabine and its metabolites at each ZT. Results indicated the levels of carboxylesterase 1 and 2, cytidine deaminase, uridine phosphorylase 2, and dihydropyrimidine dehydrogenase (p < 0.05) are being rhythmically regulated and, in turn, attributed different pharmacokinetics profiles of capecitabine and its metabolism. This study highlights the importance of capecitabine administration time to increase the efficacy with minimum adverse effects.

Phase I pharmacological study of continuous chronomodulated capecitabine treatment

Purpose

Capecitabine is an oral pre-pro-drug of the anti-cancer drug 5-fluorouracil (5-FU). The biological activity of the 5-FU degrading enzyme, dihydropyrimidine dehydrogenase (DPD), and the target enzyme thymidylate synthase (TS), are subject to circadian rhythmicity in healthy volunteers. The aim of this study was to determine the maximum tolerated dose (MTD), dose-limiting toxicity (DLT), safety, pharmacokinetics (PK) and pharmacodynamics (PD) of capecitabine therapy adapted to this circadian rhythm (chronomodulated therapy).

Methods

Patients aged ≥18 years with advanced solid tumours potentially benefitting from capecitabine therapy were enrolled. A classical dose escalation 3 + 3 design was applied. Capecitabine was administered daily without interruptions. The daily dose was divided in morning and evening doses that were administered at 9:00 h and 24:00 h, respectively. The ratio of the morning to the evening dose was 3:5 (morning: evening). PK and PD were examined on treatment days 7 and 8.

Results

A total of 25 patients were enrolled. The MTD of continuous chronomodulated capecitabine therapy was established at 750/1250 mg/m²/day, and was generally well tolerated. Circadian rhythmicity in the plasma PK of capecitabine, dFCR, dFUR and 5-FU was not demonstrated. TS activity was induced and DPD activity demonstrated circadian rhythmicity during capecitabine treatment.

Conclusion

The MTD of continuous chronomodulated capecitabine treatment allows for a 20% higher dose intensity compared to the approved regimen (1250 mg/m² bi-daily on day 1–14 of every 21-day cycle). Chronomodulated treatment with capecitabine is promising and could lead to improved tolerability and efficacy of capecitabine.

Electronic supplementary material

The online version of this article (10.1007/s11095-020-02828-6) contains supplementary material, which is available to authorized users.

Circadian variations in the pharmacokinetics of capecitabine and its metabolites in rats

Capecitabine, an orally available prodrug of 5-fluorouracil, is widely used to treat patients with colorectal cancer. Although various studies have shown circadian variations in plasma 5-fluorouracil concentrations during long-term infusion, it is still unknown whether circadian variations also exist following administration of capecitabine. The present study aimed to investigate whether the pharmacokinetics of capecitabine and its metabolites, including 5-fluorouracil, vary according to administration time in rats. Rats were orally administered capecitabine (180mg/kg) at 07:00 (23h after light onset, HALO), 13:00 (5 HALO), or 19:00h (11 HALO). Plasma concentrations of capecitabine and its metabolites, such as 5'-deoxy-5-fluorocytidine (5'-DFCR), 5'-deoxy-5-fluorouridine (5'-DFUR), and 5-fluorouracil, were determined after capecitabine administration. The results showed that the t_1/2 and AUC_0-∞ values of 5-fluorouracil differed as a function of the dosing time of capecitabine. The maximum and minimum mean t_1/2 values of 5-fluorouracil were obtained when the drug was administered at 07:00h (23 HALO: 3.1±1.2h) and 13:00h (5 HALO: 1.5±0.6h), respectively. The AUC_0-∞ value of 5-fluorouracil at 07:00h (23 HALO: 533.9±195.7μmol∙h/L) was 1.8-fold higher than the value at 13:00h (5 HALO: 302.5±157.1μmol∙h/L). The clearance of 5-fluorouracil followed a cosine circadian curve, and the simulated population mean clearance was highest at rest times and lowest during active times in rats. The results for the plasma 5'-DFCR and 5'-DFUR levels indicated that circadian variations in the sequential metabolism of capecitabine to 5-fluorouracil would also affect plasma 5-fluorouracil levels following capecitabine administration. In conclusion, the pharmacokinetics of capecitabine and its metabolites, including 5-fluorouracil, varied according to time of dosing, suggesting that the capecitabine administration time is an important factor in achieving sufficient efficacy and reducing toxicity in patients.

Chronomodulated oxaliplatin plus Capecitabine (XELOX) as a first line chemotherapy in metastatic colorectal cancer: A Phase II Brunch regimen study

PURPOSE

The aim of this study was to evaluate safety and toxicity of chronomodulated capecitabine administered in the morning and at noon according to a specific time schedule (Brunch Regimen: Breakfast and Lunch) as a part of first-line XELOX chemotherapy in patients with metastatic colorectal cancer.

METHODS

A total of 30 treatment-naïve colorectal cancer patients with metastatic disease were included. Oxaliplatin 130 mg/m(2) on day 1 plus chronomodulated oral capecitabine 2000 mg/m(2) per day were administered (50 % dose at 8:00 a.m. and 50 % dose at 12:00 noon on days 1-14, every 21 days). All adverse events, treatment responses and survival were evaluated. In addition, pharmacokinetic profile of capecitabine was examined in a subset of 5 patients.

RESULTS

Median age was 57.1 years (range 32-77 years). Median follow-up was 19 months (range 3-36 months). Three patients (10 %) had complete response, 13 patients (43.3 %) had partial response and 4 patients (13.3 %) had stabile disease. Ten patients had progressive disease at their first evaluation (33.3 %). The median progression-free survival (PFS) was 10 months (range 2-36 months). There were no grade 4 toxicities. One patient (3.3 %) had grade 3 neutropenia. Hand-foot syndrome developed in three patients (10 %): 6.6 %, grade 1 and 3.3 %, grade 2.

CONCLUSIONS

Chronomodulated XELOX seems to represent a promising therapeutic option in the first-line treatment of metastatic colorectal carcinoma due to good tumor control and favorable toxicity profile. Phase III randomized trials are required to assess the actual clinical efficacy and side effect profile of this regimen.

Chronomodulated capecitabine and adjuvant radiation in intermediate-risk to high-risk rectal cancer: a phase II study

OBJECTIVES

The aim of this study was to evaluate the feasibility and tolerability of capecitabine administration according to a specific time schedule, combined with adjuvant radiation therapy, in intermediate-risk to high-risk rectal cancer patients treated with an upfront surgery. The primary endpoint was the rate of grade 3 to 4 diarrhea during chemoradiation (CRT).

MATERIALS AND METHODS

Stage II and III rectal cancer patients received, after total mesorectal excision, 2 cycles of XELOX regimen (oxaliplatin 130 mg/m(2) on day 1; capecitabine 1000 mg/m(2) bid on day 1 to 14, q21), followed by capecitabine (800 mg/m(2) bid daily; 20% dose at 12:00 AM and 80% dose at 12:00 PM) administered continuously during pelvic radiation (total 50.4 Gy in 28 fractions, 1.8 Gy daily dose between 2:00 and 4:00 PM). Four additional cycles of XELOX were administered after chemoradiotherapy.

RESULTS

Fifty-one radically resected rectal cancer patients were enrolled. All, but one, cases were evaluated for safety of CRT. We reported a grade 3 and 4 diarrhea rate of 14% (7 of 50 patients), whereas no grade 3 and 4 leukopenia was observed. Grade 1 and 2 proctitis was observed in 26 (52%) cases, whereas grade 1 and 2 cystitis in 5 (10%) patients. Only 2 cases of grade 3 proctitis and cystitis were reported, respectively. The CRT phase was feasible and was completed by 43 (84%) patients. Three patients developed actinic enteritis 60 days after the end of the radiotherapy program.

CONCLUSIONS

Capecitabine timetable administration combined with adjuvant radiation therapy of rectal cancer is well tolerated and feasible. Further investigation of this chronomodulated schedule in terms of efficacy is warranted in neoadjuvant setting.

Neoadjuvant chronomodulated capecitabine with radiotherapy in rectal cancer: a phase II brunch regimen study

PURPOSE

The aim of this study was to evaluate efficacy and safety of chronomodulated capecitabine administered according to a specific time schedule (Brunch Regimen: Breakfast and Lunch) as a part of neoadjuvant chemoradiation therapy in patients with locally advanced rectal cancer.

METHODS

Eighty-five patients with stage II and III rectal cancer were included. Patients received capecitabine (1,650 mg/m(2) per day; 60% dose at 8:00 AM and 40% dose at 12:00 noon) administered during pelvic radiation (total 50.4 Gy in 28 fractions, 1.8 Gy daily dose between 2:00 p.m. and 4:00 p.m.). After chemoradiotherapy, patients underwent surgery. The primary endpoints were pathological complete response (pCR) rate and toxicity.

RESULTS

In 17 patients (20%), total tumor regression was achieved according to Dworak pathological grading system. Grade III diarrhea occurred in nine patients (10.5%), while only one patient had grade 3 thrombocytopenia. Grade II or III proctitis were seen in nine (10.5%) subjects, and grade I or II cystitis in six (6.9%). Only three patients (3.3%) developed hand and foot syndrome (both grade I-II). There were no grade IV toxicities.

CONCLUSIONS

Brunch Regimen for locally advanced rectal cancer consisting of neoadjuvant chronomodulated capecitabine and concurrent radiation therapy is effective and well tolerated with good safety profile, particularly with regard to the occurrence of hand and foot syndrome, in patients with locally advanced rectal cancer.

The drug efficacy and adverse reactions in a mouse model of oral squamous cell carcinoma treated with oxaliplatin at different time points during a day

Background

Recent studies have shown that the growth and proliferation of cancer cells in vivo exhibit circadian rhythm, and the efficacy and adverse reactions of platinum-based anticancer drugs administered at different times of the day vary significantly on colon cancer. However, since the circadian rhythms of growth and proliferation of various cancer cells often differ, the question of whether the administration of platinum anticancer drugs at different times of the day exerts significantly different efficacy and adverse effects on oral cancers remains to be elucidated. This study has compared the efficacy and adverse effects of oxaliplatin (L-OHP) administration at different times during a day on oral squamous cell carcinoma in mice and has analyzed cellular circadian rhythms.

Methods

The mouse model for oral squamous cell carcinoma was established in 75 nude mice, housed in a 12 hour light/12 hour dark cycle environment. The mice were randomly divided into five groups; four experimental groups were intravenously injected with L-OHP at four time points within a 24-hour period (4, 10, 16, and 22 hours after lights on [HALO]). The control group was intravenously injected with the same volume of saline. Treatment efficacy and adverse reactions were compared on the seventh day after the injection, at 22 HALO. The existence of circadian rhythms was determined by cosine analysis.

Results

Only injections of L-OHP at 16 and 22 HALO significantly prolonged animal survival time. The adverse reactions in mice injected with L-OHP at 16 and 22 HALO were significantly less than those observed in mice administered L-OHP at 4 and 10 HALO. The cosine fitting curve showed that the survival time and adverse reactions exhibited circadian rhythm.

Conclusion

The time factor should be considered when treating patients with oral squamous cell carcinoma with L-OHP in order to achieve better efficacy, reduce the adverse reactions, and improve the patients’ survival time and quality of life.

Phase I pharmacokinetic study of chronomodulated dose-intensified combination of capecitabine and oxaliplatin (XELOX) in metastatic colorectal cancer

PURPOSE

To evaluate the maximum tolerated dose (MTD) and pharmacokinetic profile of a chronomodulated, dose-intensified regimen of capecitabine in combination with oxaliplatin (XELOX) in metastatic colorectal cancer (mCRC).

METHODS

Patients (N = 18) with 0 or 1 line of prior chemotherapy received oxaliplatin 100 mg/m(2) on day 1 from 1400 to 1800 hours with escalating dose levels of capecitabine (2,500, 3,000, 3,500, 4,000, 4,500, and 5,000 mg) once daily taken at 2400 hours on days 1-5. Each cycle lasted 14 days.

RESULTS

The MTD of capecitabine was 4,500 mg. Transaminitis and anemia were the commonest non-hematologic and hematologic toxicities, respectively. Toxicities were generally mild, with only five occurrences of grade 3 toxicity and none of grade 4. There were no dose-limiting toxicities, defined as specific grade 3 or 4 toxicities occurring in the first two cycles of treatment. The objective response rate was 33.3 %, and median overall survival was 16.3 months (95 % CI: 11.2-18.2 months). The maximum plasma concentration (C(max)) and area under plasma concentration-time curve from time 0 to infinity (AUC([0-∞])) of the capecitabine metabolites in our fixed-dosing chronomodulated regimen were comparable to values seen with comparably dose-intense regimens but associated with significantly reduced toxicity.

CONCLUSIONS

Chronomodulated dose-intensified XELOX facilitates delivery of dose-intense treatment in mCRC with a favorable therapeutic index that is promising.

Circulating endothelial progenitor cells in metronomic chemotherapy using irinotecan and/or bevacizumab for colon carcinoma: Study of their clinical significance

The aim of the present study was to clarify the antitumor efficacy of metronomic chemotherapy using irinotecan (CPT-11) combined with or without bevacizumab against colon cancer, and the significance of circulating endothelial cell (CECs) and endothelial progenitor cells (CEPs) as a surrogate marker for metronomic chemotherapy. KM12SM cells were implanted into the subcutis of nude mouse. After confirming that the implanted tumors had grown 5 mm in size, group A received an intraperitoneal injection of 40 mg/kg CPT-11 every two weeks for 4 weeks [conventional maximum-tolerated dose (MTD)], group B received 10 mg/kg twice weekly (metronomic), group C received 10 mg/kg twice weekly combined with 5 mg/kg bevacizumab twice weekly (metronomic + anti-angiogenic), and the control group received 0.2 ml of PBS every week. Serial changes of CECs and CEPs in peripheral blood and microvessel density (MVD) in the tumor tissues were evaluated. The results showed that the antitumor activity in group B and in group C was significantly higher than that in group A. A significant inhibition in CEPs on day 15 in the metronomic therapy groups B and C was noted when compared to that in the control group, while there was no significant difference in CECs and CEPs between the groups on days 4 and 8. The MVD on day 15 in metronomic groups was significantly lower than that in group A. In conclusion, metronomic chemotherapy of CPT-11 with or without bevacizumab for colon cancer was more effective than the MTD therapy via anti-angiogenic effects. Sequential measurement of CEPs may be a predictive factor for the efficacy and a decisive factor for the optimal dose of metronomic therapy in colon cancer.

Circadian Timing in Cancer Treatments

The circadian timing system is composed of molecular clocks, which drive 24-h changes in xenobiotic metabolism and detoxification, cell cycle events, DNA repair, apoptosis, and angiogenesis. The cellular circadian clocks are coordinated by endogenous physiological rhythms, so that they tick in synchrony in the host tissues that can be damaged by anticancer agents. As a result, circadian timing can modify 2- to 10-fold the tolerability of anticancer medications in experimental models and in cancer patients. Improved efficacy is also seen when drugs are given near their respective times of best tolerability, due to (a) inherently poor circadian entrainment of tumors and (b) persistent circadian entrainment of healthy tissues. Conversely, host clocks are disrupted whenever anticancer drugs are administered at their most toxic time. On the other hand, circadian disruption accelerates experimental and clinical cancer processes. Gender, circadian physiology, clock genes, and cell cycle critically affect outcome on cancer chronotherapeutics. Mathematical and systems biology approaches currently develop and integrate theoretical, experimental, and technological tools in order to further optimize and personalize the circadian administration of cancer treatments.

Efficacy of oxaliplatin plus capecitabine or infusional fluorouracil/leucovorin in patients with metastatic colorectal cancer: a pooled analysis of randomized trials

PURPOSE

Six randomized phase II and III trials have investigated the role of oxaliplatin (OX) in combination with capecitabine (CAP) or infusional fluorouracil (FU) in metastatic colorectal cancer. This meta-analysis compared the efficacy of CAP/OX compared with infusional FU/OX.

PATIENTS AND METHODS

This analysis compared all published CAP/OX versus infusional FU/OX regimens. A total of 3,494 patients (FU, n = 1,737; CAP, n = 1,757) were analyzed for response rate (RR), progression-free (PFS), overall survival (OS), and toxicity.

RESULTS

The fixed-effect pooled estimate for RR showed higher RR for FU-based regimens (Odds ratio [OR] = 0.85; 95% CI, 0.74 to 0.97; P = .02) whereas the analysis of chemotherapy-only trials, excluding the bevacizumab containing NO16966 and TREE 2 trials, led to an OR of 0.74 (95% CI, 0.60 to 0.92; P = .007). However, for PFS (hazard ratio [HR] = 1.04; 95% CI, 0.96 to 1.12; P = .17) and OS (HR = 1.04; 95% CI, 0.95 to 1.12; P = .41) all models suggested similar outcome within the range of noninferiority. Grade 3/4 toxicities (thrombocytopenia-HR = 2.07, 95% CI, 1.42 to 3.03; P < .0002; diarrhea-HR = 1.34; 95% CI, 1.08 to 1.66; P < .0009; and grade 2/3 hand-foot-syndrome [HFS]-HR = 3.54; 95% CI, 2.07 to 6.05; P < .00001) were less prominent with FU-based regimens whereas neutropenia (HR = 0.15; 95% CI, 0.11 to 0.19; P < .00001) was lower in the CAP regimens.

CONCLUSION

The combination of CAP and OX resulted in lower RR, but this did not affect PFS and OS, which were similar in both treatment arms. The toxicity analysis showed the characteristic toxicity of each of the different FU schedules, with thrombocytopenia and HFS consistently more prominent in the CAP regimens.

Phase II study of oxaliplatin in combination with continuous infusion of 5-fluorouracil/leucovorin as first-line chemotherapy in patients with advanced gastric cancer

This study was designed to determine the efficacy and safety of biweekly oxaliplatin in combination with infusional 5-fluouracil (5-FU) and leucovorin in patients with advanced gastric cancer (AGC). Fifty-five eligible patients with measurable or assessable M/AGC (median age 62 and 90% of patients presented with metastasis) received oxaliplatin (85 mg/m2) intravenous infusion for 2 h, followed by intravenous infusion of 5-FU (3000 mg/m2) and leucovorin (100 mg/m2) for 46 h every 14 days until the patient's disease was either in progression, unacceptable toxicity, patient's withdrawal or the investigators' decision to discontinue treatment. Of the 55 enrolled patients, 48 were evaluable for response. Three patients (5.4%) showed complete remission and 20 patients (36.4%) achieved partial response. The overall response rate was 47.9%. Nineteen patients (34.5%) had stable disease and six patients (10.9%) showed progressive disease. The median time to progression was 5.6 months and the median overall survival was 10.8 months. Grade 3/4 toxicities included leucopenia (12.7%), thrombocytopenia (5.4%), diarrhoea (3.6%) and vomiting (9.1%). Peripheral neuropathy was noted in 61.8% of the patients (grade 1/2: 54.5%; grade 3: 7.3%). Our study confirmed that the combination of oxaliplatin and continuous infusion of 5-FU/leucoverin without bolus 5-FU as first-line chemotherapy is active for patients with AGC and relatively safe with lower haematological toxicity.

Chronomodulated capecitabine in combination with short-time oxaliplatin: a Nordic phase II study of second-line therapy in patients with metastatic colorectal cancer after failure to irinotecan and 5-flourouracil

BACKGROUND

Oxaliplatin in combination with capecitabine prolongs survival in patients with metastatic colorectal cancer (mCRC). Chronomodulation might reduce toxicity and improve efficacy.

PATIENTS AND METHODS

A phase II study examining chronomodulated XELOX(30) (XELOX(30chron)): oxaliplatin: 130 mg/m(2) on day 1, as a 30-min infusion between 1 and 3 p.m. Capecitabine: total daily dose of 2000 mg/m(2), 20% of the dose between 7 and 9 a.m. and 80% of the dose between 6 and 8 p.m. in patients with mCRC resistant to irinotecan. Seventy-one patients were enrolled. Response rate was 18%; median progression-free survival 5.1 months and median overall survival (OS) 10.2 months. Platelet count and performance status were significantly correlated to OS in multivariate analyses. Neurotoxicity grade 2 and 3 was seen in 25% and 2% of patients, respectively, other grade 3 toxic effects were as follows: nausea 6%, vomiting 3%, diarrhoea 12% (3% experienced grade 4) and palmoplantart erytem 9%.

CONCLUSION

XELOX(30chron) is a convenient second-line regimen with efficacy and safety profile similar to other oxaliplatin schedules. To further investigate chronomodulated XELOX, we have started a Nordic randomised phase II study comparing XELOX(30) and XELOX(30chron) as first-line therapy in patients with mCRC.

Chronopharmacokinetics of oral tegafur and uracil in colorectal cancer patients

Uracil-Ftorafur (UFT) combines the 5-fluorouracil (FU) prodrug tegafur with uracil (at a 1:4 molar ratio), which is a competitive inhibitor of dihydropyrimidine dehydrogenase (DPD), the limiting enzyme of FU catabolism. As a result, sustained FU concentrations are obtained in both plasma and tumor. UFT is an effective alternative to intravenous FU-Leucovorin (LV) in metastatic and adjuvant colorectal cancer treatment. A circadian rhythm for DPD activity has been shown in both human and animal studies, with consequences on FU plasma concentrations in patients receiving FU as a continuous infusion. The chronopharmacokinetics of FU has stimulated clinical trials of chronomodulated delivery schedules for floxuridine and FU infusions, suggesting that such schedules may improve the fluoropyrimidine therapeutic index. Molecular mechanisms responsible for the circadian dependence of FU pharmacodynamics include circadian rhythms in thymidylate synthase activity and DNA synthesis, as recently reported. Chronopharmacology of FU prodrugs is poorly documented. Recently, a feasibility study of chronomodulated administration of the FU oral prodrug capecitabine was reported. To our knowledge, the only study reporting on the time dependency of UFT pharmacokinetics is a phase I study by Muggia et al.