Sequence dependence of the antitumor and toxic effects of 5-fluorouracil and cis-diamminedichloroplatinum combination on primary colon tumors in mice

Combinational treatment of 5-fluorouracil and casticin induces apoptosis in mouse leukemia WEHI-3 cells in vitro

Leukemia is one of the major diseases causing cancer-related deaths in the young population, and its cure rate is unsatisfying with side effects on patients. Fluorouracil (5-FU) is currently used as an anticancer drug for leukemia patients. Casticin, a natural polymethoxyflavone, exerts anticancer activity against many human cancer cell lines in vitro, but no other reports show 5-FU combined with casticin increased the mouse leukemia cell apoptosis in vitro. Herein, the antileukemia activity of 5-FU combined with casticin in WEHI-3 mouse leukemia cells was investigated in vitro. Treatment of two-drug combination had a higher decrease in cell viability and a higher increase in apoptotic cell death, the level of DNA condensation, and the length of comet tail than that of 5-FU or casticin treatment alone in WEHI-3 cells. In addition, the two-drug combination has a greater production rate of reactive oxygen species but a lower level of Ca²⁺ release and mitochondrial membrane potential (ΔΨ_m ) than that of 5-FU alone. Combined drugs also induced higher caspase-3 and caspase-8 activities than that of casticin alone and higher caspase-9 activity than that of 5-FU or casticin alone at 48 hours treatment. Furthermore, 5-FU combined with casticin has a higher expression of Cu/Zn superoxide dismutase (SOD [Cu/Zn]) and lower catalase than that of 5-FU or casticin treatment alone. The combined treatment has higher levels of Bax, Endo G, and cytochrome C of proapoptotic proteins than that of casticin alone and induced lower levels of B-cell lymphoma 2 (BCL-2) and BCL-X of antiapoptotic proteins than that of 5-FU or casticin only. Furthermore, the combined treatment had a higher expression of cleaved poly (ADP-ribose) polymerase (PARP) than that of casticin only. Based on these findings, we may suggest that 5-FU combined with casticin treatment increased apoptotic cell death in WEHI-3 mouse leukemia cells that may undergo mitochondria and caspases signaling pathways in vitro.

Effects of 5-FU and cis-DDP Combination on Human Colorectal Tumor Xenografts

The antitumor efficacy of the cis-diamminedichloroplatinum (cisDDP) and 5 fluorouracil (5FU) combination was evaluated in a panel of eight human colorectal carcinoma xenografts. Tumors differed in origin (primary or metastatic), differentiation degree and chemotherapy treatment. Xenografts were treated with repeated i.v. injections of cisDDP, 5FU, or both drugs at 24-h interval. Compared with controls, cisDDP achieved a significant tumor growth inhibition in five out of eight tumor lines, and 5FU in four out of seven. One of two unresponsive tumor lines was significantly inhibited by the combination, that was also more effective than either drug alone (p < 0.05) in one responsive xenograft. Comparing the effects of the combination according to which drug was administered first, lower drug doses were tolerated using the cisDDP-5FU sequence, but the antitumor effects were similar at equitoxic doses. These results indicate a potential therapeutic benefit of the cisDDP-5FU combination for colorectal carcinoma patients and show that toxicity of the combination Is influenced by the drug sequence.

Phase I/II study of docetaxel, cisplatin and S-1 in locally advanced, recurrent and metastatic head and neck squamous cell carcinoma

The purpose of this study was to evaluate the maximum tolerated dose, dose-limiting toxicities and preliminary efficacy of chemotherapy with cisplatin, docetaxel and S-1 (TPS) to treat advanced head and neck squamous cell cancer. S-1 was administered orally twice daily on days 1-14 and docetaxel and cisplatin were injected intravenously on day 8, with one course lasting 4 weeks. The recommended dose obtained from a phase I study was set at docetaxel 60 mg/m(2), cisplatin 60 mg/m(2) and S-1 80 mg/m(2)/day. The phase II study revealed that the overall response rate was 81%, comprising 95% in untreated patients with localized advanced cancer and no distant metastases, 50% in untreated patients with distant metastases and 33% in previously treated patients with recurrence. The overall survival rate of untreated patients with localized advanced cancer and no distant metastases was 95% at 1 year and 64.33% at 2 years. In terms of grade 3 or higher hematotoxicity, neutropenia occurred in 100%, thrombocytotopenia in 4% and anemia in 4%. Febrile neutropenia occurred in 46%, with the rate rising to 57% in elderly patients ≥66 years. Grade 3 or higher non-hematotoxicity consisted of loss of appetite in 8%, diarrhea in 8%, hyponatremia in 13% and hypokalemia in 13%. This TPS therapy may be recommended for use as induction chemotherapy. For patients ≤65 years, the appropriate dose was docetaxel 60 mg/m(2), cisplatin 60 mg/m(2) and S-1 80 mg/m(2), whereas for those ≥66 years, it was docetaxel 60 mg/m(2), cisplatin 60 mg/m(2) and S-1 60 mg/m(2).

Prospective phase II trial of a combination of fixed dose rate infusion of gemcitabine with cisplatin and UFT as a first-line treatment in patients with advanced non-small-cell lung carcinoma

PURPOSE

The standard chemotherapy for non-elderly patients with advanced non-small-cell lung cancer (NSCLC) is platinum-based doublet combination therapy. Preclinical and clinical evidence indicates that infusion at the fixed dose rate (FDR) of 10mg/(m(2)min) may be more effective than a standard 30-min infusion of gemcitabine. In addition, oral uracil-tegafur (UFT) was associated with a survival advantage in the adjuvant setting. Therefore, we performed a phase II study using the combination of gemcitabine, cisplatin and UFT as first-line therapy in patients with advanced NSCLC.

PATIENTS AND METHODS

Eligible patients had histologically or cytologically confirmed stage IIIB or IV NSCLC with a performance status of 0-2 and were chemotherapy-naive. Gemcitabine (1,250 mg/m(2), 10mg/(m(2)min) on days 1 and 8, respectively) and cisplatin (75 mg/m(2) on day 1) were injected intravenously and UFT (400mg/day) was administered orally on days 1-14. Treatment was repeated every 3 weeks for up to six cycles. Primary endpoint was overall response rate and secondary endpoints were overall survival, time to progression and safety profile.

RESULT

Thirty-seven patients were enrolled. The median age was 60 years (range: 44-72 years). The performance status was 0 in 4, 1 in 30, and 2 in 3 patients. Twenty-three patients completed six cycles. Complete response was achieved in one (3%) patient, partial response in 17 (46%) patients, and stable disease in 10 (27%) patients. The overall response rate was 48.6% on an intention-to-treat basis and 54.5% of patients in whom a response evaluation was possible (n=33). The median survival time was 14.7 months (95% confidence interval [CI] 11.2-18.2), the 1-year survival rate was 54% and the median time to progression was 5.4 months (95% CI 4.3-6.4). Toxicities were moderate and mostly hematological adverse events. Grade 3/4 neutropenia occurred in 37% of patients and four patients experienced febrile neutropenia. Grade 3/4 anemia and thrombocytopenia occurred in 19% and 5% of patients, respectively. Non-hematological toxicities were mild.

CONCLUSION

The combination of gemcitabine, cisplatin and UFT is an active and well-tolerated first-line regimen in patients with advanced NSCLC.

In-vitro schedule-dependent interaction between oxaliplatin and 5-fluorouracil in human gastric cancer cell lines

In order to define the most effective combination schedule of oxaliplatin (L-OHP) and 5-fluorouracil (5-FU), we investigated the in vitro interaction between these drugs in a panel of four human gastric adenocarcinoma cell lines (MKN-1, NUGC-3, NUGC-5 and AZ-521). Cytotoxic activity was determined by the WST-1 assay. Different schedules of the two drugs were compared and evaluated for synergism, additivity or antagonism with a quantitative method based on the median-effect principle of Chou and Talalay. Cell cycle perturbation and apoptosis were evaluated by flow cytometry. Simultaneous and sequential treatments of L-OHP followed by 5-FU exhibited synergistic effects in all four cell lines, whereas the reverse sequence yielded a clear antagonism. 5-FU exclusively arrested cells at the G0/G1 phase, and L-OHP at the G0/G1 and G2/M phases. Apoptosis was most prominent when cells were treated simultaneously or in a sequence of L-OHP followed by 5-FU, producing apoptosis in the majority of treated cells (55.5-61.5%). In contrast, the reverse sequence yielded only 20% induction of apoptosis, the rate being not significantly different from those induced by each drug singly. Moreover, this sequence dependence was further confirmed by the experiment which compared the total number of NUGC-3 cells 7 days after these combination schedules. These findings suggest that the interaction of 5-FU and L-OHP could be highly schedule dependent, with the most efficacious interaction observed in simultaneous combination and that 5-FU followed by L-OHP would not be recommended in clinical trials for patients with advanced gastric cancer.

Feasibility study of ambulatory continuous infusion of 5-fluorouracil followed by cisplatin through hepatic artery for metastatic colorectal cancer

PURPOSE

A great synergy has been reported in a number of preclinical studies when 5-fluorouracil (5-FU) precedes cisplatin (CDDP). The objective of this study was to determine the feasibility of ambulatory continuous infusion of 5-FU followed by CDDP through hepatic artery for metastatic colorectal cancer.

PATIENTS AND METHODS

Seventeen patients with unresectable liver metastases, who underwent primary tumor resection, were treated with 5-FU (450 mg/m2/day) for seven consecutive days followed by CDDP (100 mg/body/week) for seven consecutive days, each administered continuously by using a balloon pump via Infuse-A-Port catheter inserted into common hepatic artery. The doses of drugs were reduced 20% in patients older than 70 years. The treatment was repeated every 4-6 weeks until disease progression.

RESULTS

Of 17 assessable patients, nine patients showed PR (53%; 95% CI, 29.3-76.7%) and eight patients had SD (47%; 95% CI, 23.3-70.7%), with disease control rate of 100%. The median overall survival was 26 months (95% CI: 17.5-41 months) and TTP 14 months (95% CI: 11-20.3 months). Two patients (11.8%), who showed progression due to collateral feeding arteries, responded to HAI again after occlusion. Grade 3 toxicity included leukopenia (12%) and anemia (24%). Grade 4 toxicity was absent. Four patients (23.5%) progressed at extrahepatic sites.

CONCLUSIONS

This sequential combination of 5-FU followed by CDDP through hepatic artery is active and safe in an outpatient setting, and warrants further multi-institutional study, although prevention of micrometastasis would be mandatory to further prolong overall survival.

DNA-based drug interactions of cisplatin

The interactions of cisplatin with other anti-cancer agents on the DNA level have been studied extensively in pre-clinical experiments. In general, combination of cisplatin with an antimetabolite, taxane, or topoisomerase inhibitor, can result in a modulation of platinum pharmacology on the DNA, for example, enhanced retention of the platinum-DNA adducts. These interactions are mostly sequence and cell type dependent. In cell line models, antimetabolites can enhance the number of platinum-DNA adducts, probably by inhibition of DNA repair pathways. However, in clinical trials, the opposite effect has been observed, with a reduction of these adducts upon combined treatment. For the taxanes it has been shown that they can inhibit the formation of platinum-DNA adducts, whereas topoisomerase I inhibitors increase the number of adducts, resulting in strong synergistic cytotoxicity. For this last interaction a mechanistic model has recently been proposed, in which the topoisomerase I enzyme directly binds to the platinum-DNA adduct. Thereafter, the topoisomerase I inhibitor binds to this complex, which yields large stabilised lesions to the DNA that are probably difficult to repair. Ongoing studies will proceed to elucidate the exact mechanism underlying the interactions between cisplatin and other anti-neoplastic agents on the DNA level. Such increased understanding might help in designing new and more effective treatment regimens for cancer. In this paper, we review the pre-clinical and clinical studies investigating the observed interactions between cisplatin, the antimetabolites, taxanes, and topoisomerase inhibitors on the DNA level.

Phase I study of combination chemotherapy with 5-fluorouracil (5-FU) and nedaplatin (NDP): adverse effects and eecommended dose of NDP administered after 5-FU

When nedaplatin (NDP) was used as a single agent in the phase I study, the dose-limiting toxicity (DLT) was thrombocytopenia and the recommended dose (RD) was 100 mg/m2. However, the DLT, maximum tolerated dose (MTD) and RD of NDP used in combination with 5-fluorouracil remained unknown. Therefore, we performed this study to assess the DLT and RD of NDP administered after 5-fluorouracil (5-FU). In this study, 5-FU was administered to 38 patients at a fixed dose (700 mg/m2/d on days 1-5) and NDP administered on day 6 at an initial dose of 80 mg/m2, which was subsequently increased to 100, 120, 130, 140, 150, and 160 mg/m2. The DLT of NDP was leukopenia and its MTD and RD were 160 and 150 mg/m2, respectively. Concerning impairment of renal function, only two patients had a grade I increase in serum creatinine. There were 19 responders (50%, 19/38) achieving partial response or complete response in the evaluation of antitumor effect. The result of this study is notable in that administration of 5-FU before NDP allows the dose of NDP to be substantially increased.

Synergistic induction of ICAM-1 expression by cisplatin and 5-fluorouracil in a cancer cell line via a NF-kappaB independent pathway

Cisplatin (CDDP) and 5-fluorouracil (5-FU) are common anti-tumour agents, and the anti-tumour effect of CDDP and 5-FU are synergistically enhanced by combined treatment. To clarify the mechanisms of this synergism, we examined the effect of CDDP and 5-FU on the expression of cell adhesion molecules involved in recognition of cancer cells by T lymphocytes. When NA cells, a squamous cell carcinoma cell line, were exposed to CDDP and 5-FU for 18 h, the expression of intercellular adhesion molecule-1 (ICAM-1) was synergistically induced, whereas CDDP or 5-FU alone did not induce the expression of ICAM-1, as determined by flow cytometry. Expression of ICAM-2 and ICAM-3, which are recognized by the same counter receptor on T-cells, were not up-regulated by CDDP and 5-FU. RT-PCR analysis showed that the induction of ICAM-1 on NA cells might be due to transcriptional induction of ICAM-1 mRNA. Treatment with genistein, a protein tyrosine kinase (PTK) inhibitor, inhibited the induction of ICAM-1 on NA cells by CDDP and 5-FU, whereas staurosporin, a protein kinase C inhibitor, did not. Although CDDP and 5-FU induced binding at the nuclear factor kappa B (NF-kappaB) site in the ICAM-1 promoter, pretreatment with genistein did not prevent CDDP and 5-FU-induced binding at the NF-kappaB site. Moreover, a NF-kappaB nuclear translocation inhibitor did not inhibit the induction of ICAM-1 expression by treatment with CDDP and 5-FU. The synergistic effect of CDDP and 5-FU was not specific to NA cells, since ICAM-1 was synergistically induced by CDDP and 5-FU on HSC-4 cells, a squamous cell carcinoma cell line. These findings indicate that treatment with CDDP and 5-FU induces ICAM-1 expression by a NF-kappaB independent regulatory mechanism involving PTK.

5-fluorouracil: a pharmacological paradigm in the use of cytotoxics

1. Painstaking progress in drug development is well illustrated by 5-fluorouracil (5FU), originally designed 40 years ago as a fluorinated analogue of the naturally occurring base uracil. Innovative pharmacokinetic and pharmacodynamic strategies have seen significant clinical improvements for cancer patients over the past decade. 2. 5-Fluorouracil acts by three main mechanisms. Principally, the intermediate metabolite fluorodeoxyuridine monophosphate inhibits a key enzyme in pyrimidine biosynthesis, namely thymidylate synthase (TS). Additionally, 5FU is metabolized to ribo- and deoxy-ribonucleotides, which act as false bases for incorporation into RNA and DNA. 3. Biomodulation of 5FU has been attempted with methotrexate (MTX), folinic acid, interferons, cisplatin and radiotherapy. Methotrexate augments the actions of 5FU by inhibiting dihydrofolate reductase and decreasing the folate pool required for pyrimidine biosynthesis, inhibiting TS via MTX-polyglutamate and directly inhibiting purine biosynthesis. Interferons increase steady state concentrations of 5FU. 5-Fluorouracil enhances the cytotoxicity of cisplatin and radiotherapy by inhibiting DNA repair. Folinic acid enhances TS inhibition by increasing the intracellular pool of folates that stabilize the 5FU-TS complex. 4. 5-Fluorouracil has a short plasma half-life. Thymidylate synthase inhibition is limited to the S-phase of the cell cycle and only a small fraction of most cancer cells are in S-phase at any one time. Increased response rates seen with infusional protocols may reflect the effective recruitment of additional mechanisms of cytotoxicity, not dependent on cell cycle, including effects on RNA synthesis. 5. Patients with localized metastatic disease may benefit from locoregional treatments. These include hepatic intra-arterial therapy with related compounds, such as floxuridine, which reach high concentrations at sites of tumour, while systemic toxicities are minimized by efficient hepatic clearance. 6. Recent developments include orally bioavailable formulations, such as ftorafur, capecitabine and the combination of 5FU with the dihydropyrimidine phosphate dehydrogenase inhibitor ethynyluracil. Recognition of diurnal variation in the activity of such key enzymes as DPD has led to the administration of 5FU at regulated, variable infusion rates (chronomodulation). These promising pharmacological approaches may further improve clinical outcomes in common cancers.

Sequence-dependent antitumour efficacy of combination chemotherapy of nedaplatin, a novel platinum complex, with 5-fluorouracil in an in vivo murine tumour model

The antitumour efficacy of a sequential combination of nedaplatin (NDP) and 5-fluorouracil (5-FU) was evaluated using Lewis lung carcinoma in vivo. NDP was developed as a second generation platinum complex. Because it has greater antitumour activity and lower nephrotoxicity than cisplatin (CDDP), we also compared the antitumour activity of NDP plus 5-FU with that of CDDP plus 5-FU. A fixed 5-FU dose was injected daily for 5 days and increasing doses of either NDP or CDDP were injected once via the tail vein into the Lewis lung carcinoma-implanted mice. The sequential administration of either NDP or CDDP prior to 5-FU (NF or CF therapy) resulted in severe body weight loss followed by the death of the tumour-bearing mice when the high-dose of NDP or CDDP was administered. In contrast, the sequential administration of 5-FU prior to NDP or CDDP (FN or FC therapy) resulted in synergistically enhanced inhibition of tumour growth and prolonged survival in comparison with NDP, CDDP or 5-FU monotherapy. At the high-dose of NDP in FN therapy, a reduction of tumour size and long-term tumour-free survival were frequently observed. The survival effect of the combinations of NDP with 5-FU was superior to those of the combination of CDDP with 5-FU. In conclusion, the sequence-dependent antitumour efficacy and toxicity of the combination of NDP or CDDP with 5-FU was demonstrated in this study, and FN therapy appeared to be the most efficient regimen as a clinical therapy.

Pilot study of UFT combined with 5 consecutive days cisplatin in non-small cell lung cancer

Combined use of 5-fluorouracil (5-FU) and cisplatin has proven to have synergistic effects in many experimental systems and clinical studies. UFT, an oral preparation of uracil and tegafur in a 4:1 molar ratio, was reported to have enhanced activity as compared with 5-FU or tegafur alone against various human tumors. Based on those results, we conducted a pilot study to confirm the feasibility and antitumor effect of UFT in combination with cisplatin in patients with advanced non-small cell lung cancer (NSCLC). UFT was orally administered at a dose of 400 mg/m2 according to a protocol for step-wise prolongation of the administration period, such as days 1-14 in step I, days 1-21 in step II, days 1-28 in step III. During to course, cisplatin was administered at a fixed dose of 20 mg/m2/day on days 8 through 12. The course was repeated every 4 weeks. Numbers of patients enrolled in steps I, II, III were six, ten and six (a total of 22), respectively. There were three females and 19 males, PS scored 0/1/2 = 7/14/1, stage IIIA/IIIB/IV = 3/8/11. Adenocarcinoma/squamous cell carcinoma/large cell carcinoma = 11/7/4, and median age 68 (range 52-79). All 22 patients were evaluable for toxicity, and 21 for efficacy. Compliance of UFT declined as the administration period of UFT was prolonged. In step I, one patient had grade 3 toxicity of each neutropenia, thrombocytopenia, nausea/vomiting and diarrhea. In step II, grade 3, 4 neutropenia was seen in four patients, grade 3 thrombocytopenia and anorexia in one patient, and grade 3 nausea/vomiting in four patients. In step III, there was grade 3 neutropenia in two patients and grade 3 anorexia in one patient. All other toxicities were mild. The overall response rate was 38% (one CR and 7 PR, 95% C.I.: 21-59%). Combination therapy with oral UFT and 5-day infusion of cisplatin is feasible with substantial antitumor effect against advanced NSCLC. Since UFT compliance decreased in step III (no patient in step III received > 2 courses of treatment), we considered the step II schedule to be worth for further evaluation in a combination phase II study.

The cellular interaction of 5-fluorouracil and cisplatin in a human colon carcinoma cell line

The combination of 5-fluorouracil (5-FU) and cisplatin (CDDP) has been shown to have synergistic cytotoxicity in human tumours, but the biochemical mechanism for this interaction remains unclear. Therefore, the aim of this study was to investigate the interaction of 5-FU and CDDP in a human colon carcinoma cell line, NCI H548. A 24 h exposure to 5-FU resulted in a 5-FU IC50 value of 24.2 +/- 4.5 microM, Dm 22.6 microM; exposure to CDDP for 2 h resulted in a IC50 value of 20.8 +/- 8.0 microM, Dm 21.9 microM. When cells were exposed simultaneously to 5-FU for 24 h and CDDP for the initial 2 h, or when cells were treated with CDDP for 2 h followed by various concentrations of 5-FU for 24 h, no greater than additive cytotoxicity was observed. In contrast, when cells were treated with 5-FU for 24 h prior to CDDP for 2 h, a greater than additive interaction was noted (5-FU IC50 1.2 +/- 0.6 microM, Dm 1.3 microM, CI 0.45). Thymidine 10 microM partially reversed the growth inhibitory effects of the 5-FU/ CDDP combination. Using both immunological and biochemical assays, no notable differences in the total amount of TS enzyme or the fraction of bound TS enzyme could be detected in the absence or presence of CDDP. No notable differences could be detected in intracellular reduced folate pools, FdUMP or FUTP pools, or 5-FU incorporation into RNA or DNA with the addition of CDDP to 5-FU. DNA fragmentation studies revealed that the combination of 5-FU followed by CDDP demonstrated a greater degree of single-stranded DNA fragments in parental (P = 0.024) and newly synthesised DNA (P = 0.025) compared with the administration of CDDP prior to 5-FU or either drug alone. The increase in smaller DNA fragment size was reversed with the addition of thymidine (10 microM). These findings suggest that the interaction of 5-FU and CDDP is associated with a greater degree of fragmentation of both nascent and parental DNA.

Phase II trial of 5-fluorouracil, leucovorin, interferon-alpha-2a, and cisplatin as neoadjuvant chemotherapy for locally advanced esophageal carcinoma

BACKGROUND

Most patients with esophageal carcinoma present with locally advanced disease and a poor prognosis. Surgery or radiation provides palliation for locally advanced esophageal carcinoma. The role of neoadjuvant therapy remains to be defined. We administered neoadjuvant chemotherapy consisting of 5-fluorouracil (5-FU), leucovorin, interferon-alpha, and cisplatin to 11 patients with locally advanced disease.

METHODS

Eleven patients with squamous cell or adenocarcinoma of the esophagus were treated peroperatively with two to three cycles of combination chemotherapy. Nine patients underwent resection with curative intent.

RESULTS

Six patients received three cycles of chemotherapy, and five received two. Dose reduction was necessary for two patients. One patient achieved a pathologic complete response, histologically confirmed. Of the eleven patients, two did not undergo surgery because of progressive disease during chemotherapy. Seven of the 9 patients relapsed after surgery and 2 have been disease free for 27 months.

CONCLUSIONS

The combination 5-FU leucovorin, interferon-alpha-2a, and cisplatin administered in a neoadjuvant setting resulted in a median survival of 11.8 months with a median time to relapse of 7 months.

Schedule-dependent reversion of acquired cisplatin resistance by 5-fluorouracil in a newly established cisplatin-resistant HST-1 human squamous carcinoma cell line

In vitro continuous stepwise exposure of HST-1 human squamous carcinoma cell line to cisplatin (CDDP) for 12 months resulted in a 3.5-fold stably resistant subline designated HST-1/CP0.2. Compared with parental cells, this cell line showed a 1.8-fold increase in cellular glutathione (GSH) and a 50% reduction in initial numbers of DNA interstrand cross-links (ICLs), despite similar levels of intracellular platinum accumulation. Evaluation of the kinetics of DNA ICL removal at nearly equivalent levels of DNA ICL formation indicated that HST-1/CP0.2 cells appeared to remove DNA ICLs more rapidly than do HST-1 parental cells. Thus, both elevated cellular GSH and increased DNA repair capacity would be the major factors contributing to CDDP resistance. Pretreatment of HST-1/CP0.2 cells with 5-FU, with drug-free intervals of 24 to 48 hr before exposure to CDDP, completely reversed CDDP resistance, or even increased the sensitivity to a level greater than that of parental cells, whereas the opposite sequence had no effect on resistance. In parallel with augmentation of the cytotoxicity, the levels of cellular GSH were significantly reduced over 48 hr by 5-FU pretreatment. However, depletion of cellular GSH using buthionine sulfoximine resulted in partial reversal of CDDP resistance, indicating that reduction of cellular GSH alone is not sufficient for complete reversal of CDDP resistance. Our data, together with evidence that 5-FU modulates the repair of platinum-DNA cross-links, suggest that schedule-dependent, complete reversal of CDDP resistance by 5-FU might be attributed to its inhibitory effects on both GSH levels and the repair of platinum-DNA adducts. Thus, optimization for the drug administration schedule is important when aiming at therapeutic synergy and circumvention of acquired CDDP resistance.

Effect of cisplatin in advanced colorectal cancer resistant to 5-fluorouracil plus (S)-leucovorin

Modulation of 5-fluorouracil (5-FU) is currently being investigated in advanced colorectal cancer. In an attempt to improve the results obtainable for the association of 5-FU and leucovorin, we decided to add cisplatin to 5-FU and (6S)-leucovorin (S-LV) after disease progression. The hypothesis was that a pharmacological enhancement of the efficacy of 5-FU would result in responses in 5-FU-unresponsive patients or in a second response in previously responding patients. A group of 28 5-FU+S-LV-pretreated patients, with advanced measurable colorectal cancer, were treated with 80 mg/m2 cisplatin on day 1, 80 mg/m2 S-LV and 370 mg/m2 5-FU as an i. v. bolus for 5 consecutive days every 4 weeks. We obtained 3 partial responses (response rate: 11 +/- 11%), while 11 patients had stable disease (39 +/- 18%). Among the 3 responders, 1 patient had earlier achieved a partial response, a second stable disease and 1 had disease progression after the previous 5-FU+S-LV treatment. The median survival time for all 28 patients was 11 months. Toxicity was minimal and consisted of mild and reversible gastrointestinal symptoms and myelosuppression. We believe that further studies must be carried out to establish the real impact of the synergism between cisplatin, 5-FU and S-LV in untreated patients.

A phase II trial of oral tegafur and uracil plus cisplatin in patients with inoperable nonsmall cell lung cancer

BACKGROUND

The combination of uracil and tegafur in a 4:1 molar concentration (UFT) has a greater antitumor activity than 5-fluorouracil (5-FU) and tegafur. Because the combination of 5-FU and cisplatin has been proven to have a synergistic antitumor effect in many experimental and clinical studies, a Phase II study was conducted using the combination of UFT and cisplatin in patients with inoperable nonsmall cell lung cancer.

METHODS

Thirty-one patients with measurable disease were entered into the study; all were evaluable for toxicity and response. Their median age was 61 years (range, 36-75 years). There were 13 patients with Stage III and 17 with Stage IV disease. Twenty-two (71%) patients had received no prior treatment. UFT (400 mg/m2) was administered orally on days 1 through 21 and cisplatin (80 mg/m2) was injected intravenously on day 8. This treatment was repeated every 4 weeks.

RESULTS

The median number of treatment cycles was two (range, 1-4 cycles). There were 11 partial responses (35%; 95% confidence interval, 19%-52%). The median response time was 6 months (range, 3-13 months). The median survival time was 11 months (range, 4-27+ months) for Stage III and 8 months (range, 2-22 months) for Stage IV. This chemotherapy regimen was well tolerated. The hematologic toxicities, such as leukopenia and thrombocytopenia of grades 3 and 4, occurred in only 2 of 31 (6%) patients. Nonhematologic toxicities of grades 3 or 4 were not observed.

CONCLUSIONS

Oral UFT plus cisplatin administration demonstrated an activity comparable with that of other combinations based on cisplatin and an extremely low incidence of side effects. These observations suggest that this chemotherapy regimen is worthy of further investigation in a multi-institutional trial to determine the antitumor effect and the quality of life of patients.

Preclinical and clinical aspects of biomodulation of 5-fluorouracil

Although single agent 5-FU has for many years been the standard therapy for advanced colorectal malignancies, a number of recent clinical trials show higher response rates with biomodulation of 5-FU by several different agents. In general, trials of leucovorin, methotrexate, interferon, and PALA given in biomodulatory doses and sequences with 5-FU have demonstrated comparable response rates over a broad range. However, in the absence of controlled direct comparative phase III trials, final judgement on clinical superiority of a particular regimen must be reserved. Nevertheless, on the basis of current data, certain approaches appear promising and warrant further investigation. Compared to single agent 5-FU, survival benefit has been demonstrated with both low and high dose leucovorin/5-FU regimens and response rates in the 20-50% range appear reproducibly higher than those of 5-FU alone. Low dose and either continuous infusion or repetitive dosing of leucovorin, as well as the effect of treatment sequence and intervals between drugs, require additional investigation. When given 20-24 h before 5-FU, methotrexate achieves response rates similar to leucovorin modulated 5-FU, but the potential role of rescue leucovorin used in many of the trials makes definitive interpretation difficult. Interferon/5-FU regimens attaining response rates of 30-40% are promising but need to be carefully and rationally designed. Low dose PALA with effective doses of 5-FU achieving responses in 35-45% of patients represent a marked improvement in earlier trials of high dose PALA, but additional studies with higher doses not compromising 5-FU dose intensity should be considered. Certainly, the concomitant use of multiple modulating agents also needs further investigation. While many such trials already performed attained results no better than single agent biomodulation, the preliminary results obtained by Grem and colleagues with IFN/LV/5-FU in untreated patients, and by Conti et al. using TMTX/LV/5-FU in previously treated patients are encouraging. Further understanding of the mechanisms of action and interaction of modulating agents should allow additional rational combinations to be explored clinically. Cisplatin biomodulation of 5-FU has been studied in gastrointestinal and head and neck malignancies achieving excellent results in the latter group. Preclinical evidence exists which suggests, however, that 5-FU modulation of cisplatin may be more effective, especially when 5-FU is administered 24 h or more before cisplatin. Clinical investigation of this sequence is currently lacking. Data to support the clinical promise of AZT, IdUrd, uridine, and the benzylacyclouridines are not yet available, although preclinical and preliminary clinical studies are promising.

A phase II study of combination therapy with 5'-deoxy-5-fluorouridine and cisplatin in the treatment of advanced gastric cancer with primary foci

BACKGROUND

5'-Deoxy-5-fluorouridine (5'-DFUR, doxifluridine) is a recently developed prodrug of oral 5-fluorouracil (5-FU), which is used clinically in Japan for the treatment of gastric, colorectal, and breast cancer. 5-FU has been reported to act synergistically with cisplatin (CDDP) in experimental and clinical studies. The authors conducted a multicenter Phase II study of combination therapy with 5'-DFUR and CDDP to evaluate the therapeutic usefulness of this regimen in the treatment of unresectable and advanced gastric cancers with primary foci. None of the patients had previously undergone chemotherapy. Their ages ranged from 27 to 75 years and performance status was grade 0 to 3.

METHODS

5'-DFUR (1400 mg/m2/d) was administered orally on days 1 through 4 and 15 through 18, and CDDP (80 mg/m2/d) was injected intravenously on day 5. This treatment cycle was repeated every 4 weeks. An independent panel of specialists evaluated the clinical response.

RESULTS

Fifty-one patients were studied. Clinical evaluation of response was possible in 43 patients who met the protocol requirements. The overall response rate was 50.0% (14 of 28, 95% confidence limits, 30.7%-69.4%) for patients with measurable lesions. The median duration of response was 5.2 months (156 days). The overall median survival time was 8.9 months (268 days) for evaluated patients. Therapeutic toxicity of World Health Organization (WHO) grade > or = 3 was manifested as anorexia and nausea or vomiting in 20.9% and 18.6% of the patients, respectively. However myelotoxicity and nephrotoxicity of WHO grades 3 and 4 occurred in less than 10% of the patient group. No drug-related mortality occurred.

CONCLUSIONS

Combined therapy with 5'-DFUR and CDDP is a safe and effective treatment regimen for advanced gastric cancers with primary foci which stresses the patient's quality of life, especially when used in an outpatient setting.

Metabolic basis of the synergistic antitumor activities of 5-fluorouracil and cisplatin in rodent tumor models in vivo

The biochemical mechanism of the synergy of 5-fluorouracil (FUra) and cisplatin (CDDP) was studied using transplantable tumors in rodents in vivo. The reduced folate 5,10-methylenetetrahydrofolate (CH2FH4) and its precursor tetrahydrofolate (FH4) are essential cofactors for the formation of a tight ternary complex of thymidylate synthase (TS) and 5-fluoro-2'-deoxyuridine-5'-monophosphate (FdUMP) derived from FUra. Intraperitoneal administration of CDDP (5 mg/kg) inhibited the incorporation of exogenous L-methionine into ascitic tumor cells and increased the levels of CH2FH4 and FH4 in ascitic Yoshida sarcoma and P-388 cells transplanted into rats and mice to levels about 2-3 times those measured in cells from animals that were not treated with CDDP. Preincubation with 10(-6) M FUra in Hanks' medium inhibited [6-3H]-2'-deoxyuridine incorporation into DNA of tumor cells from CDDP-treated rats 3 times more than that into cells from untreated rats, indicating that the inhibition of TS by FdUMP derived from FUra was enhanced in the presence of CH2FH4. Intraperitoneal administration of CDDP on day 1 and continuous infusion of FUra from day 1 to day 6 had synergistic effects in inhibiting tumor growth in Yoshida sarcoma-bearing rats. Oral administration of UFT, a combined form of 1 M tegafur and 4 M uracil, for 7 consecutive days beginning at 24 h after tumor implantation and a single i.p. injection of CDDP on day 1 had a significantly greater effect than did either agent alone. These results suggest that CDDP significantly enhances FUra cytotoxicity by inhibiting intracellular L-methionine metabolism and consequently increasing the reduced folate pool in mammalian tumor models in vivo.

Combination of daily 4-h infusion of 5-fluorouracil and cisplatin in the treatment of advanced head and neck squamous-cell carcinoma: a South-East European Oncology Group study

Between April 1986 and May 1989 a multicentre study was conducted to evaluate the efficacy of a 4-h intravenous infusion of 1000 mg/m2 5-fluorouracil (5-FU) followed by a 1-h infusion of 25 mg/m2 cisplatin (CDDP) given for 4 consecutive days every 4 weeks to patients with advanced squamous-cell carcinoma of the head and neck. A total of 189 consecutive patients entered the study, including 106 who had previously undergone chemotherapy and 83 who were chemotherapy-naive. Of the 165 evaluable patients, 96 (58%) responded to treatment, including 22 (13%) who achieved a complete remission (CR). In the group of previously untreated patients an objective response (CR+PR) was seen in 78% (CR, 14%) whereas in pretreated patients the response rate (CR+PR) was 40% (CR, 13%). The median survival period was 10 months. No significant difference in the duration of survival or of remission was found between the two groups in relation to previous therapy, tumour localisation, disease stage or performance status. Almost half of the patients (49%) experienced leucopenia but it was severe in only 11% of cases. Anemia (mainly WHO grades 1-2) occurred in 38% of the patients. Nausea and vomiting were common (84%). Nephrotoxicity (23%) was mild and of short duration. Moderate hair loss was seen in 42% of the patients, and phlebitis occurred in 8%. A few cases of cardiotoxicity and neurotoxicity were observed. This regimen is well tolerated and can be given even on an outpatient basis. The resultant response rate and side effects appear to be similar to those previously reported for combination chemotherapy with CDDP and continuous 5-FU infusion.

In vivo comparative therapeutic study of optimal administration of 5-fluorouracil and cisplatin using a newly established HST-1 human squamous-carcinoma cell line

The efficacy and toxicity of 5-fluorouracil (5-FU) and cisplatin (CDDP) given in a sequential combination were evaluated in nude mice transplanted with HST-1, a newly established human squamous-carcinoma cell line. 5-FU and CDDP were given i.p. for 5 days and 1 day, respectively, either as single agents or in a sequential manner separated by a 24-h interval. The treatment was repeated every 30 days. Although inhibition of tumor growth was seen in all of the treated groups after two cycles, the sequence of 5-FU followed by CDDP significantly reduced the tumor burdens throughout all three courses and was more effective than the reverse sequence or either drug alone. Neither treatment-related death nor significant hematologic or nephrologic toxicities were seen, even following three cycles of therapy. Significant weight loss was observed only in mice treated with CDDP followed by 5-FU. This sequence dependence of the activity and toxicity of the 5-FU and CDDP combination should thus be incorporated into the design of a clinical trial.

Cisplatinum in combination with 5-fluorouracil and citrovorum factor in the treatment of advanced colorectal carcinoma

A phase II trial of citrovorum factor, 500 mg/m2/week, plus 5-fluorouracil, 400 mg/m2/week on day 1, and cisplatin, 20 mg/m2/week on day 2, was carried out in a group of 40 patients with metastatic colorectal carcinoma. A partial response with a mean duration of 8.4+ months was achieved in 24% of patients, a minimal response with a mean duration of 5.4 months was obtained in 6% of patients, and a stabilization of 6.2 months was achieved in 41%. Ten patients (29%) progressed. A 38% partial response rate was seen in patients with advanced rectal carcinoma, whereas no response was obtained in patients with colon cancer. Interestingly, 5 partial responses were seen in 12 patients pretreated with 5-fluorouracil. The overall survival was 9.8+ months. The mean survival of patients who achieved a partial response was 12.0+ months, whereas patients who progressed survived a mean of 6.6+ months. Patients with colon cancer had a mean survival of 8.1+ months, and those with rectal cancer survived a mean of 11.1+ months. This difference was not statistically significant. The treatment was generally very well tolerated, with patients showing mostly grade 1-2 gastrointestinal and/or hematological toxicity.

Biochemical modification of the toxicity and the anti-tumour effect of 5-fluorouracil and cis-platinum by WR-2721 in mice

WR-2721 (ethiofos) was tested on Balb/c mice for its chemoprotective capacity against 5-fluorouracil (5FU) monotherapy. In this combination WR-2721 was not active, but WR-2721 pretreatment allowed an elevation of the cisplatin (CDDP) dose in 5FU/CDDP combination therapy in these mice. Thrombocytopenia caused by the 5FU/CDDP (100 and 7 mg/kg, respectively) therapy was prevented by WR-2721 (200 mg/kg) and a partial protection against leukopenia was observed in C57Bl/6 mice. Various WR-2721/CDDP/5FU combinations were tested on two murine colon tumour models. The best antiproliferative effect against Colon 26 (in Balb/c mice) and the lowest toxicity were found with 5FU (100 mg/kg) and CDDP (5.5 mg/kg) delivered together 30 min after WR-2721 (200 mg/kg). The increased efficacy of WR-2721/CDDP/5FU both in Colon 26 and Colon 38 (in C57Bl/6 mice) compared to single 5FU or 5FU/CDDP treatment at the same dose could not be explained by enhanced inhibition of thymidylate synthase (TS), the 5FU target enzyme. The protection by WR-2721 against toxicity of CDDP/5FU might enable the use of high doses of CDDP in this combination.

Dose reduction without loss of efficacy for 5-fluorouracil and cisplatin combined with folinic acid. In vitro study on human head and neck carcinoma cell lines

Folinic acid (FA) and cisplatin (CDDP) both potentiate the cytotoxicity of 5-fluorouracil (5-FU). The activity of various drug combinations including 5-FU, CDDP and FA was tested on two human cell lines derived from squamous cell carcinomas of the head and neck. Cytotoxicity was assessed by the semi-automated colorimetric MTT test. The drugs were tested in clinically achievable conditions (concentrations and duration of exposure). The dose response curves for 5-FU (0-100 ng ml-1) associated with FA (10(-7)-10(-5) M) reflected a progressive increase in 5-FU cytotoxicity with increasing FA concentrations. When CDDP (0-5 micrograms ml-1) was associated with 5-FU, CDDP-mediated enhancement of 5-FU cytotoxicity was apparent only when CDDP was given before 5-FU. The triple association CDDP, 5-FU and FA was also tested. In this case, for an identical final cytotoxicity, the presence of FA (10(-6) M) permitted reduction of the 5-FU concentration between 24.2 and 42% and reduction of the CDDP concentration between 13.8 and 72.7%. These observations may be beneficial for the design of more rational therapeutic trials associating CDDP, 5-FU and FA.

Biochemical pharmacology and analysis of fluoropyrimidines alone and in combination with modulators

After more than three decades since their introduction, fluoropyrimidines, especially FUra, are still a mainstay in the treatment of various solid malignancies. The antitumor effects of fluoropyrimidines are dependent upon metabolic activation. FdUMP, FUTP and FdUTP were identified as the key cytotoxic metabolites that interfere with the proper function of thymidylate synthase and nucleic acids. The relevance of these metabolites is cell-type specific. Recently, fluorouridine diphospho sugars have been detected, but the precise function of this class of metabolites is currently unknown. In mammalian systems fluoropyrimidines and their natural counterparts share the same metabolic pathways since the substrate properties in enzyme-catalyzed reactions are frequently comparable. Ongoing studies indicate that the metabolism and action of fluoropyrimidines exhibit circadian rhythms, which appear to be due to variations in the activity of metabolizing enzymes. Essential for the expanding knowledge of the pathways and effects of fluoropyrimidines has been the constant improvement of analytical methods. These include ligand binding techniques, numerous dedicated HPLC systems and 19F-NMR. Because the overall response rates achieved with fluoropyrimidines are modest, strategies based on biochemical modulation have been devised to enhance their therapeutic index. Biochemical modulators include a wide range of various compounds with different modes of action. In recently completed clinical trials, combinations of FUra with leucovorin, a precursor for 5,10-methylene tetrahydrofolate, or with levamisole, an anthelminthic with immunomodulatory activity, appeared to be superior to FUra alone. At the preclinical level combinations of fluoropyrimidines with, e.g. interferons or L-histidinol were demonstrated to be interesting candidates for further testing. The future therapeutic utility of fluoropyrimidines will depend on both the improvement of combination regimens currently used in the treatment of cancer patients and the judicious clinical implementation of promising experimental modulation strategies. Moreover, novel fluoropyrimidines with superior pharmacological properties may become important as part of or instead of modulation approaches.

Response of chemically induced primary colon tumours of the mouse to flavone acetic acid (NSC 347 512)

Flavone acetic acid (FAA) is a compound with proven activity against various transplantable colon cancers in mice. In this study it was evaluated against primary colon tumours, chemically induced by methylazoxymethanol in outbred CF1 mice. FAA was given i.v. at doses of 70 or 100 or 150 mg kg-1 every 7 days for 6 weeks. Only 4 out of 60 FAA treated mice died of toxicity. FAA reduced tumour number and tumour burden compared to control mice (P less than 0.05 at least), with no apparent dose-response relationship. Antitumour activity of FAA was comparable to that of 5-fluorouracil (5-FU) used as standard. Moreover, FAA was more effective that 5-FU against large tumours. FAA levels in plasma and different tissues (including colonic neoplastic lesions) after a single i.v. dose of 150 mg kg-1 were investigated. Tumour FAA levels appear insufficient to be responsible for the antitumour activity based only on a direct FAA cytotoxic effect. The results confirm clinical interest in FAA and suggest that mechanisms other than direct cytotoxicity may be involved in its activity.