Effects of 5-fluorouracil and the combination of 5-fluorouracil and human leukocyte interferon on human salivary gland adenocarcinoma cell line in culture

Induction of cytokines and killer cell activities by cisplatin and 5-fluorouracil in head and neck cancer patients

It has been suggested that certain antitumor agents stimulate antitumor immunity. In the present study, we examined whether cisplatin and 5-fluorouracil (5-FU) accelerate the antitumor host responses in head and neck cancer patients. Two groups of patients were studied, i.e. an untreated (UT) group and a treated, disease-free (TDF) group that received chemo-immunotherapy in combination with radiotherapy and operation. When peripheral blood mononuclear cells (PBMC) derived from head and neck cancer patients were treated with cisplatin or with 5-FU, interferon-gamma, tumor necrosis factor (TNF)-alpha, TNF-beta, interleukin (IL)-1beta, IL-6, IL-12 and IL-18 as well as killer cell activities were significantly induced in both groups. In this case, these activities induced by cisplatin in UT showed lower levels than those in TDF, whereas the activities induced by 5-FU in the UT group demonstrated almost similar levels to those in TDF. These activities were significantly inhibited by anti-asialo-GM1 antibody. Furthermore, cytokine levels in sera and killer activities of PBMC derived from the cancer patients were significantly increased after cisplatin administration. These findings suggest that cisplatin and 5-FU increase anticancer immunity mediated by induction of cytokines and killer cell activities in patients with head and neck cancer.

5-Fluorouracil and alpha-interferon in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a major cause of mortality worldwide, and no effective systematic therapy currently exists. Recombinant alpha-interferon (IFN) has been suggested to have some antitumor efficacy in this illness, and synergism with 5-fluorouracil (5-FU) has been reported in several gastrointestinal malignancies. We therefore treated 10 patients with advanced HCC with combination therapy consisting of 5-FU 750/mg/m(2) weekly and IFN 9 X 10(6) units three times weekly. Toxicity was substantial in this cirrhotic population, and included mucositis as well as neurologic and hematologic side effects. There were no sustained antitumor responses. Median survival among this heavily pretreated population was 10 months. We were therefore unable to demonstrate any significant benefit to treatment with 5-FU and IFN in patients with HCC.

New targets for pyrimidine antimetabolites in the treatment of solid tumours. 1: Thymidylate synthase

Thymidylate synthase forms the target for anticancer therapy with fluoropyrimidines. Anticancer activity can be increased by the use of different modulators of fluoropyrimidine metabolism, which lead to an enhanced inhibition of thymidylate synthase. In vitro and in vivo studies with fluoropyrimidines and two of these modulators, folinic acid (leucovorin) and interferon, are summarized. The promise of these preclinical results is reflected by the response data of several clinical trials. The biochemical effects of these modulators are described and illustrated by the fluoropyrimidine-mediated inhibition of thymidylate synthase in tumour samples, which is clearly enhanced by folinic acid. The regulation of thymidylate synthase synthesis may also be crucial for total blockade of thymidylate synthase activity. This regulation may be influenced by interferon-gamma. Although the addition of modulators increases the activity of fluoropyrimidines at the level of thymidylate synthase, most solid tumours, especially colorectal carcinomas, are resistant to these combinations. For this reason, new, more potent inhibitors of thymidylate synthase have been developed, the antifolates. Preclinical data show that some of these compounds have good antitumour activity, but they still have to prove their value in the clinic. These two approaches, the use of modulators and new compounds, have shown activity preclinically and the extension of these findings to clinical studies stresses the importance of thymidylate synthase as a target in fluoropyrimidine therapy of solid tumours.

Cytokines induce uridine phosphorylase in mouse colon 26 carcinoma cells and make the cells more susceptible to 5'-deoxy-5-fluorouridine

The antiproliferative activity of 5-fluorouracil (5-FUra) and 5'-deoxy-5-fluorouridine (5'-dFUrd), used in combination with typical cytokines and growth factors, was investigated in mouse colon 26 carcinoma cells. Tumor necrosis factor alpha (TNF alpha), interleukin-1 alpha (IL-1 alpha), and interferon gamma (IFN gamma) at low doses showing < 50% inhibition of cell growth by themselves enhanced the susceptibility of the cells to the activity of 5'-dFUrd. In particular, a mixture of these cytokines greatly enhanced the activity of 5'-dFUrd and 5-FUra by up to 12.4- and 2.7-fold, respectively, whereas the activity of other cytostatics was only slightly changed (< 1.5-fold). Basic fibroblast growth factor also increased the susceptibility, but only to 5'-dFUrd. This preferential enhancement of the activity of 5'-dFUrd would be due to induction by the cytokines of uridine phosphorylase (Urd Pase), by which 5'-dFUrd is converted to 5-FUra. TNF alpha, IL-1 alpha, IFN gamma, and a mixture of these factors increased the enzyme activity by up to 3.7-fold in colon 26 cells. Consequently, the anabolism of 5'-dFUrd to fluoronucleotides and the incorporation of 5-FUra into RNA in colon 26 cells were increased by TNF alpha treatment. In addition, the increase by the cytokine mixture in the susceptibility to 5'-dFUrd was abolished by an inhibitor of Urd Pase, 2,2'-anhydro-5-ethyluridine. These results indicate that induction of Urd Pase activity by cytokines is a critical event that increases the susceptibility to 5'-dFUrd.

Five-day infusional fluorodeoxyuridine with oral leucovorin and escalating doses of interferon alpha-2b: a phase I study

In a previous phase I study we identified the maximally tolerated dose (MTD) of a continuous intravenous infusion of fluorodeoxyuridine (FUdR) to be 0.3 mg/kg daily for 5 days when combined with oral leucovorin (LV) given at 100 mg q4h. In an attempt to modulate FUdR further, we added escalating doses of interferon alpha-2b (IFN) to FUdR/LV in a phase I cohort study. A total of 36 patients with refractory solid tumor were treated at two dose levels of FUdR and five dose levels of IFN. Although the initial patient cohort was treated with a dose of FUdR lower than that previously identified as the MTD [FUdR at 0.2 mg/kg daily with LV at 100 mg q4h and IFN at 2 million units (MU)/m2 daily], three of six patients developed grade 3 mucositis, indicating that the toxicity of FUdR/LV was increased in the presence of low doses of IFN. After decreasing the FUdR dose to 0.1 mg/kg daily, we could increase the dose of IFN from 2 to 30 MU/m2 daily in five additional cohorts of patients. With increasing IFN doses, no increase in mucositis or dermatitis was observed, indicating no further potentiation of FUdR/LV toxicity with higher IFN doses. However, known toxicities of IFN, including transient myelosuppression and hepatic transaminase elevation, were observed more frequently at IFN doses of 15 and 30 MU/m2 daily, where they became dose-limiting. We conclude that IFN modulates FUdR/LV at low doses, resulting in increased FUdR toxicity. When the dose of IFN is increased, this FUdR/LV toxicity does not appear to be potentiated further and IFN-related toxicities become dose-limiting.

The effects of gamma-interferon combined with 5-fluorouracil or 5-fluoro-2'-deoxyuridine on proliferation and antigen expression in a panel of human colorectal cancer cell lines

Gamma-Interferon (IFN-gamma) and the antimetabolites 5-fluorouracil (5-FU) and 5-fluoro-2'-deoxyuridine (FUdR) were investigated as individual agents and in combination for their in vitro antiproliferative capacity and for their effect on the expression of HLA class-I antigen, carcinoembryonic antigen (CEA) and the intracellular tumor-associated antigen CTA-I in 7 human colorectal cancer cell lines: WiDr, HT29, Colo 205, SW116, LS174T, SW1398, and LoVo. Growth inhibition by IFN-gamma at clinically relevant concentrations (50-100 U/ml) was found in 4/7 cell lines. The cell lines were equally sensitive to 5-FU (IC50 in a range of 2-10 microM), while sensitivity to FUdR varied considerably (IC50 in a range of 0.01-90 microM). When 50 U/ml IFN-gamma were combined with 5-FU or FUdR, the antiproliferative effects were synergistic in those cell lines with sensitivity to IFN-gamma as a single agent, but not in the IFN-gamma-insensitive cell lines. IFN-gamma was able to enhance the expression of HLA Class I and CEA in 4/7 and 3/7 cell lines, respectively, as measured by flow cytometry. CTA-I expression could not be enhanced with IFN-gamma. The expression of the 3 antigens tested was also increased by 5-FU and FUdR. This effect was concentration-dependent in most instances and varied between the individual cell lines. The combination of 50 U/ml IFN-gamma with 25% growth-inhibitory concentration of 5-FU or FUdR for each cell line resulted in an additional increase in antigen expression in 4/7 cell lines. No relation was found between the enhancement of antigen expression and the sensitivity to IFN-gamma or the anti-metabolites. The enhancement in antigen expression also did not show a relationship with changes in cell-cycle distribution upon exposure to IFN-gamma or the anti-metabolites. These results suggest independent mechanisms for the antiproliferative and antigen-enhancing effects of IFN-gamma, 5-FU and FUdR.

The use of clonogenic assays in assessing the response of human lung cancer cell lines to alpha and gamma interferons alone or in combination with adriamycin

The antiproliferative and cytotoxic effects of purified IFN-alpha and recombinant IFN-gamma were investigated using both direct cell counting and a clonogenic assay on a panel of 5 established human lung cancer cell lines and for 2 of them also on their multidrug-resistant counterparts. There was considerable heterogeneity in the response of the cell lines to the IFNs in terms of growth inhibition. Clonogenic assay of IFN-treated cells indicated that, where a cell line had responded markedly to an IFN, only a small fraction of the cells remaining after IFN treatment were clonogenically viable. When cells were placed into the clonogenic assay in the presence of IFNs, the time course of colony formation was different from that seen in the control cultures for most of the cell lines. The measured "surviving fraction" was greatly dependent upon the time of colony counting. When the effects of IFNs in combination with ADM were studied, conclusions regarding the interaction of the effects of the agents also depended upon the time at which colonies were counted.

Enhancement of cis-diamminedichloroplatinum and mitomycin C-induced sister chromatid exchanges by dibutyryl cyclic AMP in a human salivary gland adenocarcinoma cell line in culture

A human salivary gland adenocarcinoma cell line was cultivated in the presence of dibutyryl cyclic AMP (dB-cAMP), cis-diammine dichloroplatinum (cisplatin) or mitomycin C (MMC) only, or of the combination of dB-cAMP and each of the antineoplastic drugs. Then the treated cells were examined for the induction of sister chromatid exchanges (SCEs), colony-forming efficiency (CFE) in semisolid agar medium and cell survival as measured by counting for viable cells. It has been found that the frequency of SCE induction is significantly increased by treatment of cells with cisplatin or MMC under the presence of dB-cAMP, when compared to that in the cells treated with cisplatin or MMC only. Moreover, marked reduction in CFE and cell survival was found to occur in the cells treated with the combination of dB-cAMP and cisplatin or MMC. These finding indicate that treatment of a human salivary gland adenocarcinoma cell line with dB-cAMP results in modification of SCE induction, CFE and cell survival in the cells exposed to cisplatin or MMC.

Recombinant leukocyte A interferon with doxorubicin. A phase I study in advanced solid neoplasms and implications for hepatocellular carcinoma

A pilot study was performed on seven patients with advanced solid neoplasms. They received recombinant leukocyte interferon A (rIFN-alpha A) 12 X 10(6) U/m2 intramuscularly daily for 5 days plus doxorubicin, 25 mg/m2 IV on day 3 of each monthly cycle (Roferon-A, Hoffman-LaRoche, Nutley, NJ). Because of side effects, the dose was not increased above the initial level. There was a striking partial response of biopsy-confirmed hepatocellular carcinoma for 6+ months along with a decrease in alpha-fetoprotein from 39,000 to 202 ng/mL. The doxorubicin dose is approximately 33% to 42% of the typical single-agent dose, thus suggesting that the clinical toxicity from these two agents is additive.

Three consecutive phase II studies of recombinant interferon alfa-2a in advanced malignant melanoma. Updated analyses

In three consecutive Phase II trials of recombinant interferon alfa-2a (rIFN alfa-2a; Roferon-A Hoffmann-La Roche, Nutley, NJ) involving 96 patients with advanced malignant melanoma, an overall response rate of 22% was observed. For all study participants, the median time to disease progression was 1.7 months, and the median survival was six months. Most regressions occurred within one month of commencing therapy, were usually limited to soft tissue metastases, and were transient. However, responses in three patients were long term, lasting 32+, 36+, and 41+ months. A thrice weekly intramuscular dose of 50 x 10(6) U/m2 produced an intolerable flulike illness concomitant with a median weight loss of 5.6 kg. The addition of cimetidine to the same dose in 35 patients was of no therapeutic value. A dose of 12 x 10(6) U/m2 produced clinically acceptable toxicities, and a median weight loss of 2.1 kg. There was no apparent dose response relationship, nor were there any obvious sequelae from antibody formation to interferon alfa-2a. As single agent therapy in malignant melanoma, interferon alfa-2a was only marginally useful in most patients. Nevertheless, combination regimens of this agent with cytotoxic agents, alternative molecular species of interferon, and lymphokines, notably tumor necrosis factor, offer a conceptually intriguing dimension in the design of future clinical trials.

Synergistic antiproliferative effect of human interferons in combination with mismatched double-stranded RNA on human tumor cells

Four human tumor cell lines were studied for their response to antiproliferative effects of various interferons (IFNs) alone and in combination with the novel mismatched dsRNA, r(I)n r(C12,U)n (Ampligen). RT4 cells (bladder carcinoma) were resistant to Ampligen alone, while A2182 (lung carcinoma), HT 1080 C14 (fibrosarcoma) and RT112 (bladder carcinoma) cells were inhibited in a dose-dependent manner. In contrast, RT4 cells were sensitive to the antitumor effects of IFNs as were HT1080 C14 and RT112 cells, while A2182 cells were resistant. In 3 of 4 cell lines, the recombinant IFNs were less effective than the corresponding natural IFNs when compared by analysis of variance on an IRU/ml basis over a range of concentrations. In all cell lines, a synergistic antiproliferative effect was seen with all IFN preparations studied in combination with Ampligen, as calculated by the isobole method according to Berenbaum (1981). The antiproliferative effect of IFN was potentiated greater than 3.3- to greater than 250-fold, depending on the cell lines, IFN, and concentrations used. Varying the concentration of beta ser-IFN while holding the Ampligen concentration constant gave synergy at all of the physiologically achievable concentrations tested in RT4 cells. These results indicate that: Ampligen worked synergistically with all IFNs in all cell lines studied; growth inhibition of cells resistant to IFNs can be potentiated by low doses of Ampligen; the antiproliferative effect of IFNs can be potentiated by Ampligen in Ampligen-resistant cells; and Ampligen may work by a mechanism other than, or in addition to, the induction of IFNs.