Prolonged and enhanced suppression of thymidylate synthase by weekly 24-h infusion of high-dose 5-fluorouracil

Dose-dense TPF induction chemotherapy for locally advanced head and neck cancer: a phase II study

BACKGROUND

Phase 3 studies suggest that induction chemotherapy (ICT) of cisplatin and 5-fluorouracil plus docetaxel (TPF) is effective but toxic for patients with squamous-cell carcinoma of the head and neck (SCCHN). Dose-dense chemotherapy may yield favorable outcomes compared with standard-dose chemotherapy, yet the optimal induction regimen remains undefined. We assessed the efficacy and tolerability of biweekly dose-dense TPF ICT in patients with SCCHN.

METHODS

In this prospective phase II study, We enrolled patients with stage III/IV (AJCC 7th edition) unresectable squamous cell carcinoma of head and neck cancer. Patients received dose-dense TPF (ddTPF) with cisplatin and docetaxel 50 mg/m2 on day 1, leucovorin 250 mg/m2 on day1, followed by 48-h continuous infusion of 2500 mg/m2 of 5-fluorouracil on day 1 and 2, every 2 weeks for 6 cycles followed by radiotherapy. The primary endpoint was the response rate (RR) after ICT.

RESULTS

Fifty-eight patients were enrolled from June 2014 to September 2015. Overall RR after ICT was 89.6% [complete response (CR), 31%; partial response (PR), 58.6%]. Grade 3/4 neutropenia, mucositis, and diarrhea incidences were 25.9, 1.7, and 1.7%, respectively. 94.8% of patients completed all treatment courses of ICT without dose reduction. The 3-year overall survival (OS) was 54.3% (95%CI: 39.7 to 66.8%) and progression-free survival (PFS) was 34.3% (95%CI: 22.0 to 46.9%). Multivariate analysis showed that CR after ICT is an independent prognostic factor for OS and PFS.

CONCLUSIONS

Six cycles of ddTPF is an active, well-tolerated induction regimen for patients with SCCHN. The presence of CR after ICT predicted long-term survival.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04397341 , May 21, 2020, retrospectively registered.

Suppressive effect of sinomenine combined with 5-fluorouracil on colon carcinoma cell growth

It is reported that sinomenine (SIN) and 5-fluorouracil (5-FU) both are effective for colon cancer, but their cooperative suppressive effects and toxicity remain to be clarified in detail. This study aimed to determine suppressive effects and toxicity of sinomenine (SIN) plus 5-fluorouracil (5-FU) on LoVo colon carcinoma cells in vitro and in vivo. CCK-8, Hoechst 33258 staining and an annexin V-FITC/PI apoptosis kit were used to detect suppressive effects. Western blotting was applied to investigate the essential mechanism underlying SIN and 5-FU-induced apoptosis. SIN or 5-FU or both were injected into nude mice, and then suppressive effects and side effects were observed. SIN plus 5-FU apparently inhibited the proliferation of LoVo cells and induced apoptosis. Moreover the united effects were stronger than individually (p<0.05). The results of annexin V-FITC /PI staining and Hoechst 33258 staining showed that the percentage of apoptotic cells induced by SIN and 5-FU combined or alone was significantly higher than the control group (p<0.05). Expression of Bax and Bcl-2 was up-regulated and down-regulated respectively. SIN or 5-FU significantly inhibited effects on the volume of tumour xenografts and their combined suppressive effects were stronger (p<0.05). No obvious side effects were observed. It was apparent that the united effects of SIN and 5-FU on the growth of colorectal carcinoma LoVo cells in vitro and in vivo were superior to those using them individually, and it did not markedly increase the side effects of chemotherapy.

Synergistic effects of puerarin combined with 5-fluorouracil on esophageal cancer

Puerarin is an isoflavone derived from kudzu roots with a wide range of biological and medicinal properties. The aim of the present study was to investigate the inhibitive effects of puerarin combined with 5‑fluorouracil (5‑FU) on Eca‑109 esophageal cancer cells in vitro and in vivo. Inhibitive effects of the treatments on Eca‑109 cells were detected by cell counting kit‑8, Hoechst 33258 staining and flow cytometry. A tumor xenograft model was established in nude mice. Puerarin and 5‑FU, administered either in combination or individually, were injected into mice and the inhibitive effects along with any side effects were observed. Apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Puerarin and 5‑FU, administered as combined treatment or individual drugs, significantly inhibited proliferation and induced marked apoptosis. The mean growth inhibition rate (± standard deviation) reached 87.27±5.37% and the apoptotic rate at 48 h reached 36.18±1.24% in the combined treatment group. The percentages of apoptotic cells induced by puerarin and 5‑FU (combined or alone) were significantly higher than those of the control group (P<0.05). Puerarin or 5‑FU alone significantly inhibited the growth of xenograft tumors in comparison to the control group (P<0.05), with inhibition rates of 76.93 and 72.21%, respectively. The drugs combined exhibited a significantly greater effect than either drug alone (P<0.05), with the tumor inhibition rate reaching 89.06%. During the course of chemotherapy, no evident side effects were observed. The results suggested that the combined inhibitive effects of puerarin and 5‑FU were greater than the effects of the agents used individually. In addition, puerarin combined with 5‑FU exhibited synergistic effects at lower concentrations and promoted apoptosis, but did not increase the side effects of chemotherapy, which indicated that puerarin may be a safe and effective chemosensitive agent in the treatment of human esophageal cancer.

Cooperative inhibitory effect of sinomenine combined with 5-fluorouracil on esophageal carcinoma

AIM: To investigate the inhibitory effects of sinomenine (SIN) combined with 5-fluorouracil (5-FU) on esophageal carcinoma in vitro and in vivo.

METHODS: Esophageal carcinoma (Eca-109) cells were cultured in DMEM. The single or combined growth inhibition effects of SIN and 5-FU on the Eca-109 cells were examined by measuring the absorbance of CCK-8 dye in living cells. Hoechst 33258 staining and an Annexin V/PI apoptosis kit were used to detect the percentage of cells undergoing apoptosis. Western blotting was used to investigate the essential mechanism underlying SIN and 5-FU-induced apoptosis. SIN at 25 mg/kg and 5-FU at 12 mg/kg every 3 d, either combined or alone, was injected into nude mice and tumor growth inhibition and side effects of the drug treatment were observed.

RESULTS: SIN and 5-FU, both in combination and individually, significantly inhibited the proliferation of Eca-109 cells and induced obvious apoptosis. Furthermore, the combined effects were greater than those of the individual agents (P < 0.05). Annexin V/PI staining and Hoechst 33258 staining both indicated that the percentage of apoptotic cells induced by SIN and 5-FU combined or alone were significantly different from the control (P < 0.05). The up-regulation of Bax and down-regulation of Bcl-2 showed that the essential mechanism of apoptosis induced by SIN and 5-FU occurs via the mitochondrial pathway. SIN and 5-FU alone significantly inhibited the growth of tumor xenografts in vivo, and the combined inhibition rate was even higher (P < 0.05). During the course of chemotherapy, no obvious side effects were observed in the liver or kidneys.

CONCLUSION: The combined effects of SIN and 5-FU on esophageal carcinoma were superior to those of the individual compounds, and the drug combination did not increase the side effects of chemotherapy.

Geographic difference in safety and efficacy of systemicchemotherapy for advanced gastric or gastroesophagealcarcinoma: a meta-analysis and meta-regression

BACKGROUND

The standard of chemotherapy regimens for advanced or metastatic gastric cancer and the clinical outcome were heterogeneous in Asian versus non-Asian countries. This study aimed to explore predictors of safety and efficacy of chemotherapy for patients with advanced or metastatic gastric cancer.

METHODS

Treatment group-based meta-analysis and met a regression were performed to analyze results of randomized trials published since 2005 for advanced or metastatic gastric cancer patients who received systemic chemotherapy as first-line treatment. Data were extracted and synthesized according to the Cochrane guidelines.

RESULTS

Twenty-five trials (8 Asian, 17 Western or international) with 56 treatment groups were analyzed. Asian trials reported a lower percentage of gastroesophageal junctional carcinoma, higher percentage of diffuse type histology, and more frequent use of second-line chemotherapy. Meta-analysis revealed significant heterogeneity both in treatment safety (grade 3–4 neutropenia and diarrhea) and efficacy [6-month progression-free survival(PFS) and 1-year overall survival (OS)]. Meta-regression analyses indicate that Asian trials are associated with an 8.2% lower incidence of grade 3–4 neutropenia and 2.1%lower incidence of grade 3–4 diarrhea. A lower percentage of patients with gastroesophageal junction carcinoma and the use of combination regimens predicted better PFS. The use of second-line chemotherapy predicts better 1-year OS,which will increase by 10% for every 10% increase inpatients who received second-line chemotherapy.

CONCLUSION

Geographic region (Asian vs. non-Asian) is an independent predictor of safety in systemic therapy for gastric cancer.

Induction of thymidine kinase 1 after 5-fluorouracil as a mechanism for 3'-deoxy-3'-[18F]fluorothymidine flare

Imaging the pharmacodynamics of anti-cancer drugs may allow early assessment of anti-cancer effects. Increases in 3'-deoxy-3'-[(18)F]fluorothymidine ([(18)F]FLT) uptake early after thymidylate synthase inhibition (TS) inhibition, the so-called flare response, is considered to be largely due to an increase in binding sites for type-1 equilibrative nucleoside transporter. We investigated the induction of thymidine kinase 1 (TK1) after 5-fluorouracil (5-FU) treatment as one of mechanisms for [(18)F]FLT flare. Exposure of nine cancer cell lines to 5-FU for 24h induced a 2.5- to 3.5-fold increase in [(18)F]FLT uptake, significantly higher than the 1.5-fold increase observed 2h after treatment. The increase of [(18)F]FLT uptake 24h after 5-FU exposure accompanied TK1 induction in most cell lines. In representative cell lines (A431 and HT29), 5-FU time-dependently increased [(18)F]FLT uptake, kinase activity and the levels of protein and mRNA for TK1, sequential cyclin E and A induction, and G(1)-S phase transition. Cycloheximide treatment and knockdown of TK1 completely inhibited 5-FU-induced [(18)F]FLT flare. On the other hand, HCT8 cells showed a biphasic [(18)F]FLT flare with lacked TK1 induction in response to the dosage of 5-FU. Cycloheximide did not inhibit 5-FU-induced [(18)F]FLT flare in this cells. In vivo dynamic [(18)F]FLT-PET and ex vivo analysis in HT29 tumor-bearing mice showed significantly increased [(18)F]FLT flux and TK1 activity of tumor tissue 24h after 5-FU administration (P<0.05). Conclusively, 5-FU induced TK1 and TK1-mediated high [(18)F]FLT flare in most of cell lines. [(18)F]FLT-PET may be used to assess pharmacodynamics of TS inhibitor by a mechanism involving TK1 induction.

Modified FOLFOX-6 chemotherapy in advanced gastric cancer: Results of phase II study and comprehensive analysis of polymorphisms as a predictive and prognostic marker

Background

The objective of this study was to evaluate the efficacy and toxicity of infusional 5-fluorouracil (5-FU), folinic acid and oxaliplatin (modified FOLFOX-6) in patients with advanced gastric cancer (AGC), as first-line palliative combination chemotherapy. We also analyzed the predictive or prognostic value of germline polymorphisms of candidate genes associated with 5-FU and oxaliplatin.

Methods

Seventy-three patients were administered a 2 hour infusion of oxaliplatin (100 mg/m²) and folinic acid (100 mg/m²) followed by a 46 hour continuous infusion of 5-FU (2,400 mg/m²). Genomic DNA from the patients' peripheral blood mononuclear cells was extracted. Ten polymorphisms within five genes were investigated including TS, GSTP, ERCC, XPD and XRCC.

Results

The overall response rate (RR) was 43.8%. Median time to progression (TTP) and overall survival (OS) were 6.0 months and 12.6 months, respectively. Toxicities were generally tolerable and manageable. The RR was significantly higher in patients with a 6-bp deletion homozygote (-6 bp/-6 bp) in TS-3'UTR (55.0% vs. 30.3% in +6 bp/+6 bp or +6 bp/-6 bp, p = 0.034), and C/A or A/A in XPD156 (52.0% vs. 26.1% in C/C, p = 0.038). The -6 bp/-6 bp in TS-3'UTR was significantly associated with a prolonged TTP and OS. In a multivariate analysis, the 6-bp deletion in TS-3'UTR was identified as an independent prognostic marker of TTP (hazard ratio = 0.561, p = 0.032).

Conclusion

Modified FOLFOX-6 chemotherapy appears to be active and well tolerated as first line chemotherapy in AGC patients. The 6-bp deletion in TS-3'UTR might be a candidate to select patients who are likely to benefit from 5-FU based modified FOLFOX-6 in future large scale trial.

Bimonthly 24 h infusion of high-dose 5-fluorouracil vs EAP regimen in patients with advanced gastric cancer. A randomized phase II study

BACKGROUND

To investigate the activity and toxicity of high dose (HD) infusional 5-FU in comparison to EAP regimen as first-line chemotherapy in patients with advanced gastric cancer.

PATIENTS AND METHODS

Histologically confirmed measurable advanced gastric cancer, age < 72 yr, ECOG performance status 0-2, no prior chemo- and radiotherapy, adequate organ functions.

TREATMENT

EAP arm: doxorubicin (40 mg/m(2)), etoposide (360 mg/m(2)), and cisplatin (80 mg/m(2)) every 28 d; HD 5-FU arm: 5-FU 2.6 g/m(2) 24 h infusion, biweekly.

RESULTS

Sixty patients were randomized. Patient characteristics (arms EAP/HD 5-FU): Median age 57/55 yr, median PS 1/1, LAD (patients) 3/8, M1 (patients) 27/22. Median number of cycles (range): EAP arm 4 (2-8), HD 5-FU arm 2 (1-8). Worst toxicity per cycle (grade 3 and 4 in%): Neutropenia 20/3, thrombocytopenia 9/0, anemia 9/13, diarrhea 3/10, nausea 17/7, vomiting 10/0 for EAP and HD 5-FU arms, respectively. All patients were eligible for response in both arms. Confirmed response rate (95%CI): EAP arm 34% [16-50%]/HD 5-FU arm 10% (0-21%), no change: 46/40%, progression of disease: 20/50, respectively. Overall survival (range): EAP arm A 7 mo [3-27], HD 5-FU arm 6 mo (4-25).

CONCLUSIONS

Infusional HD 5-FU showed a low incidence of severe toxicity. But given the low efficacy of 5-FU in the dosage we applied in the study, it cannot be recommended as a single treatment for further studies. Assessment of higher dose intensity and/or dose density of 5-FU, with introduction of other active drugs in combination, could be an option for further studies.

Synergistic effect of triptolide combined with 5-fluorouracil on colon carcinoma

AIM

To investigate the inhibitive effects of triptolide (TPL) combined with 5-fluorouracil (5-FU) on colon carcinoma HT-29 cells in vitro and in vivo and their side effects.

METHODS

HT-29 cells were cultured with RPMI 1640 medium. The single or combined effects of TPL and 5-FU on HT-29 cells were examined by MTT assay, flow cytometry. The combined effects were evaluated by the median-effect principle. The model of tumour xenografts was established in nude mice. TPL 0.25 mg/kg/day and 5-FU 12 mg/kg/day, either in combination or on their own, were injected into mice and the inhibitive effects and side effects were observed.

RESULTS

TPL and 5-FU either combined or alone inhibited significantly the proliferation of HT-29 cells and induced obvious apoptosis. Mean (SD) growth inhibition rate reached 94.92 (2.76)% and the apoptic rate at 48 h reached 41.71 (1.38)%. The combined effects were synergistic (CI<1) at lower concentrations. TPL or 5-FU alone inhibited significantly the growth of tumour xenografts and the inhibition rates were 78.53% and 84.16%; the drugs combined had more significant effect, the tumour inhibition rate reaching 96.78%. During the course of chemotherapy, no obvious side effect was observed.

CONCLUSION

The combined effects of TPL and 5-FU on the growth of colon carcinoma in vitro and in vivo were superior to the effects when the agents were used individually. TPL combined with 5-FU had synergistic effects at lower concentrations and promoted apoptosis, but did not increase the side effects of chemotherapy.

Synergistic effects of matrine and 5-fluorouracil on tumor growth of the implanted gastric cancer in nude mice

OBJECTIVE

To investigate the inhibitive effects of matrine and 5-fluorouracil (5-FU) on the growth of human gastric adenocarcinoma cell line SGC-7901 when transplanted into nude mice and to investigate the bone marrow toxicity of these compounds.

METHODS

50 mg/kg and 100 mg/kg matrine with 50 mg/kg 5-FU, and 50 mg/kg matrine only, 50 mg/kg 5-FU only were intraperitoneally injected to observe their inhibitive effects by calculating the relative tumor volume (RTV) and tumor inhibition rates (IR%) as shown by the number of nucleated cells and bone marrow cell colony culture.

RESULTS

The tumor inhibitive effect of the combined 100 mg/kg matrine and 50 mg/kg 5-FU group was stronger than that of the combined 50 mg/kg matrine and 50 mg/kg 5-FU groups (P < 0.05), and were also much stronger than that of the control group (50 mg/kg matrine only, 50 mg/kg 5-FU only, P < 0.01). As for the bone marrow inhibition effect, there was no significant statistical difference between the combination group and 5-FU alone group. In the cultured bone marrow cell colony, exuberant growth was seen in the combination group, but not in the control group.

CONCLUSIONS

The inhibitive effect of combined matrine and 5-FU on the growth of transplanted human gastric cancer in nude mice is superior to that of matrine or 5-FU alone. Combined matrine and 5-FU can increase the inhibitive effect on proliferative hemopoietic bone marrow cells in nude mice and does not affect the resting bone marrow stem cells.

Phase II study of weekly paclitaxel and 24-hour infusion of high-dose 5-fluorouracil and leucovorin in the treatment of recurrent or metastatic gastric cancer

To investigate the efficacy and safety of combining weekly paclitaxel with weekly 24-hour infusion of high-dose 5-fluorouracil (5-FU) and leucovorin (LV, folinic acid) in the treatment of patients with advanced gastric cancer. Patients with histologically confirmed recurrent or metastatic gastric cancer were studied. Paclitaxel 80 mg/m2 3-hour intravenous infusion was given on days 1, 8, and 15, and high-dose 5-FU 2,600 mg/m2 plus LV 300 mg/m2 24-hour intravenous infusion (HDFL) was given on days 2, 9, and 16, repeated every 4 weeks. Between August 1997 and August 2003, 30 patients were enrolled. The median age was 58 years (range: 37-70). Eighteen patients (60.0%) had recurrent or metastatic disease and 12 patients had de novo metastatic disease. Among the 27 patients evaluable for tumor response, 2 achieved complete response and 9 achieved partial response, with an overall response rate of 40.7% (95% confidence interval, CI: 22-61%). Eleven of the 21 patients without prior exposure to HDFL-containing regimens responded (response rate: 52.4%, 95% CI: 29-74%), while none of the 6 patients who had previously failed HDFL-containing regimens responded (p value = 0.054 by Fisher's exact test). All 30 patients were evaluated for survival and toxicities. Median time to progression and overall survival were 6 and 10 months, respectively. Major grade 3-4 toxicities were neutropenia in 12 patients (40.0%), diarrhea in 10 patients (33.3%), and stomatitis in 3 patients (10.0%). Grade 1-2 and 3-4 paclitaxel-related neuropathy developed in 16 (53.3%) and 2 (6.7%) patients, respectively. None of the patients discontinued protocol treatment because of paclitaxel-related neuropathy or developed HDFL-related hyperammonemic encephalopathy. This paclitaxel-HDFL regimen is effective and well tolerated in the treatment of advanced gastric cancer.

Phase II study of weekly vinorelbine and 24-h infusion of high-dose 5-fluorouracil plus leucovorin as first-line treatment of advanced breast cancer

We prospectively investigated the efficacy and safety of combining weekly vinorelbine (VNB) with weekly 24-h infusion of high-dose 5-fluorouracil (5-FU) and leucovorin (LV) in the treatment of patients with advanced breast cancer (ABC). Vinorelbine 25 mg m⁻² 30-min intravenous infusion, and high-dose 5-FU 2600 mg m⁻² plus LV 300 mg m⁻² 24-h intravenous infusion (HDFL regimen) were given on days 1 and 8 every 3 weeks. Between June 1999 and April 2003, 40 patients with histologically confirmed recurrent or metastatic breast cancer were enrolled with a median age of 49 years (range: 36–68). A total of 25 patients had recurrent ABC, and 15 patients had primary metastatic diseases. The overall response rate for the intent-to-treat group was 70.0% (95% CI: 54–84%) with eight complete responses and 20 partial responses. All 40 patients were evaluated for survival and toxicities. Among a total of 316 cycles of VNB–HDFL given (average: 7.9: range: 4–14 cycles per patient), the main toxicity was Gr3/4 leucopenia and Gr3/4 neutropenia in 57 (18.0%) and 120 (38.0%) cycles, respectively. Gr1/2 infection and Gr1/2 stomatitis were noted in five (1.6%) and 59 (18.7%) cycles, respectively. None of the patients developed Gr3/4 stomatitis or Gr3/4 infection. Gr2/3 and Gr1 hand–foot syndrome was noted in two (5.0%) and 23 (57.5%) patients, respectively. Gr1 sensory neuropathy developed in three patients. The median time to progression was 8.0 months (range: 3–25.5 months), and the median overall survival was 25.0 months with a follow-up of 5.5 to 45+ months. This VNB–HDFL regimen is a highly active yet well-tolerated first-line treatment for ABC.

Current Status of Clinical Studies for Colorectal Cancer in Taiwan

The incidence and age-adjusted mortality of colorectal cancer (CRC) has drastically increased in the past 2 decades in Taiwan. Fortunately, chemotherapy for metastatic CRC also showed improvement in terms of tumor response rate and survival in the corresponding time period. For its low toxicity profile and high objective response rate (17.5%-31.9% in patients who received low-dose 5-fluorouracil [5-FU] that failed and 53.3%-61.5% in patients who were chemotherapy-naive), weekly 24-hour infusion of high-dose 5-FU and leucovorin (LV) has been a favorable regimen for advanced CRC for medical oncologists in Taiwan. Investigators also put their effort in exploring the mechanisms of high efficacy and low toxicity profile of this regimen, as well as the prognostic factors in predicting tumor response to this regimen. With the emergence of new, active compounds for metastatic CRC, a simple 2-hour infusion of oxaliplatin plus 46-hour infusion of 5-FU/LV every 2 weeks has become a favorable regimen, with an overall response rate (ORR) of 40%-50% and overall survival of 18.2 months in chemotherapy-naive patients. Conversely, there were also studies to suggest that biweekly oxaliplatin plus weekly or biweekly bolus 5-FU/LV was shown to achieve a comparable tumor response and survival in 5-FU-refractory metastatic CRC. In patients who had been treated with oxaliplatin plus infusional 5-FU/LV that failed, salvage biweekly irinotecan plus bolus and infusional 5-FU/LV could achieve an ORR of 22.2% with a median duration of response of 8 months. As for oral fluoropyrimidine analogues, oral tegafur/uracil and capecitabine are available in Taiwan. In addition, a clinical trial of dendritic cell-based immunotherapy for chemotherapy-refractory metastatic CRC has also been initiated and is in progress.

Phase II study of weekly oxaliplatin and 24-h infusion of high-dose 5-fluorouracil and folinic acid in the treatment of advanced gastric cancer

To investigate the efficacy and safety of combining weekly oxaliplatin with weekly 24-h infusion of high-dose 5-fluorouracil (5-FU) and folinic acid (FA) in treatment of patients with advanced gastric cancer. Patients with histologically confirmed, locally advanced or recurrent/metastatic gastric cancer were studied. Oxaliplatin 65 mg m⁻² 2-h intravenous infusion, and 5-FU 2600 mg m⁻² plus FA 300 mg m⁻² 24-h intravenous infusion, were given on days 1 and 8, repeated every 3 weeks. Between January 2001 through January 2002, 55 patients were enrolled. The median age was 64 years (range: 22–75). In all, 52 patients (94.5%) had recurrent or metastatic disease and three patients had locally advanced disease. Among 50 patients evaluable for tumour response, 28 patients achieved partial response, with an overall response rate of 56% (95% confidence interval (CI): 41.8–70.3%). All 55 patients were evaluated for survival and toxicities. Median time to progression and overall survival were 5.2 and 10.0 months, respectively, during median follow-up time of 24.0 months. Major grades 3–4 toxicities were neutropenia in 23 cycles (7.1%) and thrombocytopenia in 16 cycles (5.0%). Treatment was discontinued for treatment-related toxicities in nine patients (16.4%), of whom eight were due to oxaliplatin-related neurotoxicity. One patient (1.8%) died of neutropenic sepsis. This oxaliplatin-containing regimen is effective in the treatment of advanced gastric cancer. Except for neurotoxicity that often develops after prolonged use of oxaliplatin, the regimen is well tolerated.

Weekly gemcitabine plus 24-h infusion of high-dose 5-fluorouracil/leucovorin for locally advanced or metastatic carcinoma of the biliary tract

Both gemcitabine and weekly 24-h infusion of high-dose 5-fluorouracil/leucovorin (HDFL) have shown promising antitumour activity for patients with locally advanced or metastatic carcinoma of the biliary tract (CBT). From April 1999 through December 2002, 30 patients with inoperable CBT were treated with gemcitabine 800 mg m⁻², intravenous infusion for 30 min, followed by 5-FU, 2000 mg m⁻² and leucovorin, 300 mg m⁻², intravenous infusion for 24 h, on day 1, 8 and 15, every 4 weeks. A total of 166 cycles were given (median of four cycles per patient, range 1–24 cycles). Response was evaluable in 28 patients and toxicity in 29 patients. Partial response was obtained in six patients, stable disease in 13, while progressive disease occurred in nine. The objective response rate was 21.4% (95% CI: 5.2–37.6%). The most common grade 3 or 4 toxicity was infection (nine patients). Other types of grade 3 or 4 toxicity included leucopenia (four patients), thrombocytopenia (three patients), anaemia (three patients), nausea/vomiting (two patients) and elevation of liver transaminases (three patients). As of 30 September 2003, the median progression-free survival was 3.7 months (95% CI: 2.8–4.6 months) and the median overall survival was 4.7 months (95% CI: 0.8–8.6 months). Our data suggest that weekly gemcitabine plus HDFL is modestly active with acceptable treatment-related toxicity for patients with advanced CBT.

Low Thymidylate Synthase Expression in the Primary Tumor Predicts Favorable Clinical Outcome in Resected Gastric Cancer Patients Treated with Adjuvant Tegafur

OBJECTIVE

To assess the thymidylate synthase protein (TS) in tumor cells of resected gastric cancer patients treated with adjuvant tegafur (TG), we reviewed the outcome of 94 randomized patients treated either with adjuvant TG plus mitomycin C (MMC) or MMC alone.

METHODS

TS was determined in 76 out of 94 patients, previously randomized to receive adjuvant TG, 500 mg/m(2)/day p.o. for 6 months plus four courses of MMC, 10- 20 mg/m(2) i.v. every 6 weeks or MMC alone. An immunohistochemical assessment with the monoclonal antibody TS-106 was performed.

RESULTS

Low TS was observed in 38 patients (20 treated with TG-MMC and 18 with MMC) and high TS in the other 38 patients (21 treated with TG-MMC and 17 with MMC). After 10 years' median follow-up time, 61% of adjuvant TG-MMC patients and 43% of MMC patients were alive and disease-free. Disease-free survival and overall survival were significantly better for patients treated with TG-MMC compared to MMC adjuvant (p = 0.0277 and p = 0.05), and low-TS compared to high-TS patients (p = 0.0184 and p = 0.0198). In 38 low-TS patients we observed an 83% chance to be disease-free in TG-MMC-treated patients and 55% in MMC-treated patients (p = 0.04).

CONCLUSIONS

A low TS level determines a subset of patients that may benefit from adjuvant oral TG when added to MMC showing a 5-year cure rate of more than 80%.

Down-regulation of thymidylate synthase expression and its steady-state mRNA by oxaliplatin in colon cancer cells

Recently, evidence has accumulated that weekly 24-h infusion of high-dose 5-fluorouracil (5-FU) with leucovorin (LV, folinic acid) biochemical modulation may improve the response rates compared with the bolus 5-FU regimens in colorectal cancer (CRC). Combining the infusional 5-FU/LV (iFL) regimens with oxaliplatin or irinotecan is widely adopted to further improve treatment efficacy. Either oxaliplatin-iFL or irinotecan-iFL may achieve an overall response rate of more than 50% in the first-line treatment. Intriguingly, in the salvage treatment for metastatic CRC patients who had failed iFL, only oxaliplatin-iFL may achieve a response rate of about 13-25%. In contrast, oxaliplatin alone or irinotecan-iFL had a very low response rate of 5% or less. To test if the oxaliplatin may reverse the iFL-related 5-FU resistance in CRC, we used DLD-1 colon adenocarcinoma cells as the in vitro study model. First, we revealed that oxaliplatin and 5-FU act synergistically on DLD-1 cells by MTT cytotoxicity assay and median drug effect analysis. Second, we treated the DLD-1 cells with serial concentrations of oxaliplatin (0.1-10 microM). Oxaliplatin treatment results in down-regulation of free thymidylate synthase (TS) protein expression by Western blotting. Further, we analyzed the TS mRNA level by reverse transcription and real-time quantitative polymerase chain reaction assay. Oxaliplatin treatment results in down-regulation of the TS mRNA level up to 40% (mean +/- SD of ratio to reference control = 0.60 +/- 0.21, range 0.42-0.84). In this study, our data provide important information explaining the reason why the combination of oxaliplatin and 5-FU results in a better objective response in 5-FU-resistant patients than oxaliplatin alone does. Our data also suggest that TS down-regulation happens at the transcriptional level. TS modulation and down-regulation had, thus, shed light on the useful potential strategy to achieve objective responses in 5-FU-resistant CRC patients.