Concentration and time dependence of the toxicity of fluorinated pyrimidines to HT 29 colorectal carcinoma cells

Patient-centered developments in colon- and rectal cancer with a multidisciplinary international team: From translational research to national guidelines

Rarely, scientific developments centered around the patient as a whole are published. Our multidisciplinary group, headed by gastrointestinal surgeons, applied this research philosophy considering the most important aspects of the diseases "colon- and rectal cancer" in the long-term developments. Good expert cooperation/knowledge at the Comprehensive Cancer Center Ulm (CCCU) were applied in several phase III trials for multimodal treatments of primary tumors (MMT) and metastatic diseases (involving nearly 2000 patients and 64 centers), for treatment individualization of MMT and of metastatic disease, for psycho-oncology/quality of life involving the patients' wishes, and for disease prevention. Most of the targets initially were heavily rejected/discussed in the scientific communities, but now have become standards in treatments and national guidelines or are topics in modern translational research protocols involving molecular biology for e.g., "patient centered individualized treatment". In this context we also describe the paths we had to tread in order to realize our new goals, which at the end were highly beneficial for the patients from many points of view. This description is also important for students and young researchers who, with an actual view on our recent developments, might want to know how medical progress was achieved.

Fabrication and Use of Poly(d,l-lactide-co-glycolide)-Based Formulations Designed for Modified Release of 5-Fluorouracil

5-fluorouracil (5-FU) is a chemotherapeutic agent that has been used for the treatment of a variety of malignancies since its initial introduction to the clinic in 1957. Owing to its short biological half-life, multiple dosings are generally required to maintain effective 5-FU plasma concentrations throughout the therapeutic period. Clinical studies have shown that continuous 5-FU administration is generally superior to bolus injection as exhibited by lower toxicities and increased therapeutic efficacy. Optimal therapeutic efficacy, however, is often compromised by the limiting therapeutic index. Whilst oral formulations are also used, these suffer from the drawbacks of variable bioavailability and first-pass metabolism. As a result, sustained release formulations of 5-FU have been investigated in an effort to mimic the kinetics of continuous infusion particularly for situations where local delivery is considered appropriate. The biocompatible, biodegradable, and highly tunable synthetic polymer, poly(d,l-lactide-co-glycolide) (PLGA), is widely used as a vector for sustained drug delivery, however, issues such as insufficient loading and inappropriate burst release kinetics have dogged progress into the clinic for small hydrophilic drugs such as 5-FU. This review provides introductory information about the mechanism of action, pharmacokinetic and physicochemical properties, and clinical use of 5-FU that have contributed to the development of PLGA-based 5-FU release platforms. In addition, this review provides information on fabrication methods used for a range of 5-FU-loaded PLGA formulations and discusses factors affecting the release kinetics of 5-FU as well as the in vitro and in vivo antitumor or antiproliferative efficacy of these platforms.

Pharmacokinetic properties and antitumor efficacy of the 5-fluorouracil loaded PEG-hydrogel

Background

We have studied the in vitro and in vivo utility of polyethylene glycol (PEG)-hydrogels for the development of an anticancer drug 5-fluorouracil (5-FU) delivery system.

Methods

A 5-FU-loaded PEG-hydrogel was implanted subcutaneously to evaluate the drug retention time and the anticancer effect. For the pharmacokinetic study, two groups of male rats were administered either an aqueous solution of 5-FU (control group)/or a 5-FU-loaded PEG-hydrogel (treated group) at a dose of 100 mg/kg. For the pharmacodynamic study, a human non-small-cell lung adenocarcinoma (NSCLC) cell line, A549 was inoculated to male nude mice with a cell density of 3 × 10⁶. Once tumors start growing, the mice were injected with 5-FU/or 5-FU-loaded PEG-hydrogel once a week for 4 weeks. The growth of the tumors was monitored by measuring the tumor volume and calculating the tumor inhibition rate (IR) over the duration of the study.

Results

In the pharmacokinetic study, the 5-FU-loaded PEG-hydrogel gave a mean residence time (MRT) of 8.0 h and the elimination half-life of 0.9 h; these values were 14- and 6-fold, respectively, longer than those for the free solution of 5-FU (p < 0.05). In the pharmacodynamic study, A549 tumor growth was significantly inhibited in the 5-FU-loaded PEG-hydrogel group in comparison to the untreated group beginning on Day 14 (p < 0.05-0.01). Moreover, the 5-FU-loaded PEG-hydrogel group had a significantly enhanced tumor IR (p < 0.05) compared to the free 5-FU drug treatment group.

Conclusion

We suggest that 5-FU-loaded PEG-hydrogels could provide a useful tool for the development of an anticancer drug delivery system.

Regional chemotherapy of nonresectable colorectal liver metastases with mitoxantrone, 5-fluorouracil, folinic acid, and mitomycin C may prolong survival

BACKGROUND

Regional chemotherapy of isolated, nonresectable colorectal liver metastases (CRLMs) by hepatic artery infusion (HAI) has the advantages of high response rates and the possibility of downstaging and resection of CRLMs. 5-Fluorodeoxyuridine (5-FUDR) has been the drug studied in most Phase II and III trials. The meta-analysis of the Phase III trials comparing HAI with systemic or supportive therapy confirmed an advantage for response and even survival for HAI. Hepatic artery infusion with 5-FUDR, however, is hepatotoxic, inducing sclerosing cholangitis (SC). The authors have introduced 5-fluorouracil (5-FU) with folinic acid for HAI and found equal effectivity but no SC when compared with HAI with 5-FUDR. Now, they report a new combination chemotherapy protocol based on HAI with 5-FU with FA and on in vitro Phase II studies suggesting mitoxantrone and mitomycin C as active drugs for HAI in CRLM. PATIENTS AND METHODS Between February 1993 and August 2000, 63 patients with CRLM were treated with HAI using mitoxantrone, 5-FU with FA, and mitomycin C (MFFM) via port catheters with a protocol planing up to 11 cycles of treatment. Toxicity and response were analyzed according to World Health Organization (WHO) criteria, and survival was analyzed according to Kaplan-Meier. All patients were treated with more than two HAI cycles.

RESULTS

The objective response rate (complete remission and partial remission) was 54% and primary intrahepatic progression (progressive disease) occurred in 4.8%, whereas in 41.3% of the patients the intrahepatic disease was evaluated as no change. Median survival times from the first diagnosis of CRLM or start of HAI were 25.7 months and 23.7 months, respectively, and 7 patients lived longer than 40 months. Grade 3 toxicity according to WHO occurred in 34.9%, and Grade 4 occurred in 3.2%. No toxic death or SC occurred.

CONCLUSIONS

Our new HAI protocol with MFFM seems to be superior to HAI with 5-FUDR, 5-FU with FA, and systemic chemotherapy with 5-FU and FA at acceptable toxicity. Currently, HAI with MFFM is compared with systemic chemotherapy using 5-FU and FA intravenously in a randomized Phase III trial.

Pre-clinical evaluation of the activity of gemcitabine as a basis for regional chemotherapy of pancreatic and colorectal cancer

AIMS

To estimate the potential activity of gemcitabine for hepatic arterial infusion (HAI) chemotherapy in pancreatic and colorectal cancer.

METHODS

The anti-proliferative effects of gemcitabine were determined in MIA PaCa-2 and PMH2/89 pancreatic and HT29 and NMG64/84 colon cancer cell lines and in fresh tumours from patients with liver metastases of colon, rectal and pancreatic cancer in vitro using the human tumour colony forming assay.

RESULTS

Gemcitabine showed concentration and time-dependent cytotoxic effects in all tested cell lines. The IC(50)of gemcitabine in MIA PaCa-2, PMH2/89, HT29 and NMG64/84 cells at 2 h exposure time were >100, 18, 100 and 2.5 microg/ml, respectively, at 4 h 15, 1.2, 45 and 0.5 microg/ml, respectively, and at 24 h 0.2, 0.1, 1.8 and 0.1 microg/ml, respectively. All tumours displayed concentration dependent inhibition of colony formation after exposure to gemcitabine for 2 h. The IC(50)values of gemcitabine in six of the 10 metastases were </=100 microg/ml.

CONCLUSIONS

Based on our results and theoretical considerations regarding hepatic arterial infusion therapy gemcitabine seems to be suitable for HAI therapy phase II studies. Moreover, patients with colorectal or pancreatic tumours that demonstrated in vivo sensitivity may benefit from regional chemotherapy with gemcitabine.

In vitro concentration response studies and in vitro phase II tests as the experimental basis for regional chemotherapeutic protocols

The theoretical pharmacologic benefit of regional vs. systemic chemotherapy is defined and the concentration response behavior of cytostatic drugs and their optimal exposure times are described with human cancer cell lines (HT29, NMG64/84) and fresh human tumor cell suspensions in the human tumor colony assay (HTCA). The theoretical pharmacological advantages are 5.8 to 6 for adriamycin (ADM), 8 for cisplatinum (CDDP), 6.3 for epidoxorubicin (EPI), 22 to 58 for 5-fluorouracil (5FU), 4.6 for mitomycin C (MMC), and 6.3 for mitoxantrone (NOV). The drugs differed in their cytotoxic potency in vitro and thus also potential efficacy for regional chemotherapy; however, all but 5-fluorodeoxyuridine (5FUDR) exerted cytotoxicity dependent on exposure time and concentration. On average, elevation of the test concentrations by 1 lg doubled responses in fresh human tumor cell suspensions. From these results and clinical considerations, optimal times were defined for the regional chemotherapy strategies of hepatic artery infusion, intraperitoneal instillation, and chemoembolisation as performed at our institution.

Adjuvant treatment of colon and rectal cancer: impact of chemotherapy, radiotherapy, and immunotherapy on routine postsurgical patient management. Forschungsgruppe Onkologie Gastrointestinaler Tumoren (FOGT)

Colon cancer patients with UICC stage III or T4 N0 M0 stage II should receive postoperative adjuvant therapy, since relapse rates are high and surgical outcome has been improved by adjuvant treatment. The standard treatment is 5-fluourouracil plus levamisole; an alternative option is the combination of 5-fluourouracil and folinic acid. Stage II (T3 N0 M0) colon cancer patients should not receive adjuvant treatment outside of studies. Rectal cancer patients of stage II or III should receive postoperative radiochemotherapy with 45-54.4 Gy and 5-fluourouracil as standard treatment. Patients not eligible for radiotherapy may receive adjuvant chemotherapy only. Studies need to be conducted to improve adjuvant therapy in colorectal cancer. All qualified patients should be treated within these studies requiring sufficient patient numbers, as well as comparable surgical procedures, proper patient selection and stratification criteria, drug and dose intensities. Intraportal infusion may be as effective as systemic adjuvant treatment; the tumor type and stage for which benefit from this kind of treatment is consistently significant needs to be defined, since intraportal infusion of all resectable colorectal cancers is overtreatment. Both surgery and histopathological staging may be improved in some centers, and these require standardization and quality control.

The syndrome of 5-fluorouracil cardiotoxicity. An elusive cardiopathy

BACKGROUND

A case of reversible cardiogenic shock linked to 5-fluorouracil (5-FU) was observed. Recognizing the increasing use of 5-FU, the authors tried to map this syndrome.

METHODS

They reviewed 134 additional case reports, retrieved information from literature searches, focused on clinical features, and discussed possible pathophysiologic findings and prevention of this syndrome.

RESULTS

Although angina and electrocardiographic changes were common and reproducible (approximately 90% each), coronary artery disease was found in a few patients. A total of 33 patients had severe left ventricular dysfunction, 28 without evidence of myocardial infarction. The symptoms were responsive to conservative management (90%).

CONCLUSIONS

Cardiac toxicity is a little known complication of 5-FU therapy, with an unknown but significant incidence. It is highly treatable.

Effects of FUdR on primary-cultured colon carcinomas metastatic to the liver

Hepatic arterial infusion of fluorodeoxyuridine (FUdR) has demonstrated efficacy in the treatment of metastatic colorectal carcinoma of the liver. In this study, the direct cytotoxic effect of FUdR was measured on ten metastatic and two primary-site colorectal carcinomas in a primary culture assay system. Overall, clinically achievable concentrations of FUdR (0.4 to 4 microM) induced partial cell kill in 75% of tumors, including a greater than 50% reduction in viable tumor cell number in only two tumors and less than 50% in the remaining seven. Total cell kill was not observed in any tumor. Three tumors were resistant to these FUdR concentrations. Tumor sensitivity correlated with the size of the tumor growth fraction. Increasing the exposure time to FUdR from 3 to 7 days approximately doubled the magnitude of the response. 5-Flurouracil and cisplatin, at clinically achievable concentrations, were more toxic to metastatic tumor cells than FUdR. Because of the limited chemosensitivity of metastatic colorectal tumor cells to FUdR in vitro, we postulate that other mechanisms besides direct cytotoxicity contribute to the clinical efficacy of FUdR in vivo.

Effect of 5-fluorouracil combination therapy on RNA processing in human colonic carcinoma cells

We have evaluated the RNA-directed cytotoxicity of 5-fluorouracil (5-FU) in human colonic carcinoma cells. The mode of action of 5-FU and its effects on human pre-rRNA processing were then examined. From these data, possible reasons why the disruption of pre-rRNA maturation could induce cytotoxic effects are considered. The results imply that inhibition of thymidylate synthase is not the sole primary cytotoxic lesion in this cell line. First, exogenous thymidine (dTHd) enchanced cytotoxicity. Second, addition of dThd to the cells was found to enhance incorporation of 5-FU into total cellular RNA. Third, 5-FU disrupted rRNA processing by a different mechanism from actinomycin D and methotrexate (MTX), suggesting that the inhibition was not just a consequence of cell death. Finally, the addition of dThd was found to enhance the disruption of rRNA processing consistent with an increase in concentration of 5-FU. These data are discussed in the light of literature reports and their potential for optimising 5-FU protocols.

Pharmacokinetic modulation of plasma 5-fluorouracil concentrations to potentiate the antitumor activity of continuous venous infusion of 5-fluorouracil

Methods for pharmacokinetic modulation of the plasma 5-fluorouracil (5-FU) level to increase antitumor activity during continuous venous infusion (CVI) of low doses of 5-FU were examined in Yoshida sarcoma-bearing rats. These methods were additional infusion of 5-FU for a short period (4 h) or oral administration of UFT or Tegafur during long-term CVI of 5-FU that alone gave a plasma 5-FU level of about 50 ng/ml. The antitumor effect on Yoshida sarcoma was markedly potentiated when an additive dose of 5-FU combined with 3-cyano-2,6-dihydroxypyridine (CNDP), a potent inhibitor of 5-FU degradation, giving a plasma level of about 500 ng/ml, was infused for 4 h. A similar increase in the antitumor effect was observed with oral administration of a conventional dose of UFT during CVI of 5-FU without CNDP, giving a plasma level of 30 to 60 ng/ml. These results suggest that the antitumor effect of CVI of 5-FU can be potentiated by pharmacokinetic modulation of the 5-FU concentration in the blood.

Increased cytotoxicity of low-dose, long-duration exposure to 5-fluorouracil of V-79 cells with hyperthermia

We examined the cytotoxic effects of combined low dose and long exposure to 5-fluorouracil (5-FU) and hyperthermia on Chinese hamster V-79 cells with reference to timing and sequence of administration. The survival rate following hyperthermia at 42 degrees C for 2 h alone was 95.4%, and that after exposure to 1.0 micrograms/ml/5-FU alone for 48 hours, 94.2%. With respect to the combination of 5-FU and heat, the survival rate of cells exposed to hyperthermia at 42 degrees C for 2 h followed by 1.0 micrograms/ml 5-FU treatment for 48 h followed by hyperthermia led to a survival rate of 10%. Flow cytometric analysis of V-79 cells after exposure to 1.0 micrograms/ml 5-FU for 48 h revealed an accumulation of cells in the S-phase; the percentage of S-phase exponential growing cells was 65% and the plateau phase was 38%. The former were more sensitive to heat than the latter cells according to the MTT assay. V-79 cells pretreated with 5-FU were more sensitive to hyperthermia than were those not pretreated with 5-FU. Therefore, when 5-FU plus heat is to be used to treat a patient with a malignancy, the sequence of 5-FU followed by hyperthermia may be more effective than the reverse.