Cytoplasmic membrane cholesterol and doxorubicin cytotoxicity in drug-sensitive and multidrug-resistant human ovarian cancer cells.

The possible involvement of cholesterol (CHOL) in the cellular transformations leading to the acquisition of the multidrug-resistance (MDR) phenotype has been evaluated in human ovarian cancer cells. To this end, the A2780 cell line and the 52-fold doxorubicin (DX)-resistant counterpart A2780-DX3 were analyzed under two different growth conditions: standard culture medium (FCS medium), or medium deprived of CHOL (LPDS medium). The following variables were investigated: free and esterified cytoplasmic membrane CHOL, cell growth, DX uptake and cytotoxicity, and low-density lipoprotein uptake and degradation (as indirect variables of CHOL homeostasis). The impact of the calcium antagonist verapamil (VER) on these variables was assessed. The results obtained indicate that under standard growth conditions, A2780 and A2780-DX3 cells are different not only with respect to DX uptake and sensitivity, but also with respect to membrane CHOL content and the ratio of free-to-esterified CHOL. The deprivation of lipoproteins in the culture medium, apart from slowing cell growth, induced a decrease in the cytoplasmic membrane CHOL content (mainly of the esterified form) that was particularly evident in A2780 sensitive cells. In LPDS medium, a reduced DX uptake occurred in both cell lines, but to a greater extent in A2780 cells, in which DX cytotoxicity decreased to values comparable to that of A2780-DX3 resistant cells. Restoration of DX sensitivity was achieved with the addition of 10 microM VER.(ABSTRACT TRUNCATED AT 250 WORDS)

Membrane gangliosides and immuno-mediated cytolysis in drug sensitive and treatment-induced multidrug resistant human ovarian cancer cells.

The pattern of cytoplasmic membrane gangliosides and two cellular features which have been reported to be related to the expression of different membrane gangliosides, namely adhesion to solid substrates and susceptibility to the lytic activity of immune effector cells, have been investigated in drug sensitive A2780 human ovarian cancer cells and in two treatment-induced multidrug resistant sublines (A2780-DX1 and A2780-DX3). The total membrane gangliosides content of A2780 sensitive cells was comparable to that of the two multidrug resistant (MDR) sublines, but the acquisition of the MDR phenotype was characterized by an increased expression of the polysialylated gangliosides (particularly the disialoganglioside GDIa) and decreased expression of the monosialoganglioside GM2. The kinetics of cellular adhesion (both to plastic culture dishes and to extracellular matrix coated dishes) were similar in the three cell lines, indicating that the gangliosides profile seems not to be relevant for cell adhesivity to the above mentioned substrates. When human peripheral blood lymphocytes in toto (PBL) and two lymphokine activated (LAK) T cell subpopulations (CD3+4-8- and CD3-16+) were used as effector cells against A2780 (sensitive) and A2780-DX3 (highly resistant) cells, cytolysis of target cells was more efficient against the A2780-DX3 subline, suggesting a possible role of the ganglioside GD1a as a target structure for LAK immunotherapy.

Enhancement of the antitumor effects of 5-fluorouracil by folinic acid.

Although 5-fluorouracil (FUra) is one of the most effective cytotoxic agents in the treatment of various solid tumors (carcinomas of the gastro-intestinal tract, breast, head and neck), remissions occur in only 20-30% of cases and usually are of short duration. Recently, preclinical studies have shown that the antitumor activity of FUra can be potentiated by modulating the metabolism of this drug by using other substances, in particular 5-formyltetrahydrofolate (folinate, LV). Reduced folates (LV and 5-methyltetrahydrofolate) at concentrations greater than or equal to 1 microM can, by raising the intracellular levels of 5,10-methylenetetrahydrofolate, increase and prolong the inhibition of the target enzyme, thymidylate synthase, with formation of a stable ternary complex formed by the enzyme, the folate coenzyme and the fluoropyrimidine inhibitor (5-fluorodeoxyuridylate). After phase II clinical trials reported encouraging results with the combination LV-FUra in the treatment of patients with various solid tumors, randomized controlled studies in patients with colorectal carcinoma have documented an increase in the response rate of the combination compared to treatment with FUra alone. The integration of the LV-FUra combination into multidrug regimens is now under investigation for the treatment of carcinomas of the breast, stomach, and head and neck.

Generation and characterization of a low-degree drug-resistant human tumor cell line.

A 2780 human ovarian cancer cells, obtained from an untreated patient, have been exposed to a relatively low, clinically maintainable dose (10 nmol/l) of the anthracycline doxorubicin (DX) to derive a low-degree (5-fold) drug-resistant subline (A2780-DX1). Compared to parental cells, these DX-resistant cells have increased size (+60% of cell volume) and contain a greater number of cytoplasmic vacuoles as determined by electron microscopy. When exposed to several other antiproliferative drugs, A2780-DX1 cells were highly cross-resistant (greater than 10-fold) to epirubicin, mafosfamide and cisplatin and slightly cross-resistant (2- to 3-fold) to navelbine and bleomycin, while they retained the original sensitivity to vinblastine, Ara-C and fluorouracil. Gel electrophoresis of cytoplasmic membrane proteins showed differences between the pattern of parental A2780 sensitive and A2780-DX1 cells as far as low-molecular-weight proteins (less than 45 kD) are concerned, while no clear overexpression of P-glycoprotein (P-170) could be detected. Membrane modifications yielding a decrease of both DX uptake and retention, increased content of intracellular glutathione (+32%) and reduced DNA double-strand breaks seem to be involved in the resulting multidrug-resistant phenotype of A2780-DX1 cells.

Effect of the tiapamil analog RO11-2933 on cellular sensitivity to antitumor drugs in sensitive and multidrug resistant human ovarian cancer cells.

The ability of the Tiapamil analog N-(3,4 Dimethoxyphenyl)-N-methyl-2-(naphthyl)-m-dithiane-2-propylamine hydrocloride (RO11-2933) to influence the cytotoxic activity of Doxorubicin (DX) and seven other antitumor agents was evaluated in sensitive and treatment-induced multidrug resistant human ovarian cancer cells. In vitro treatment of A2780 sensitive cells with 1 microM RO11-2933 for 72hr potentiated by less than 3-fold the cytotoxic effects of each antitumor drug tested, with the exception of Cisplatin and Fluorouracil, which were potentiated by 7.2- and 5.0-fold, respectively. In A2780-DX3 resistant cells, RO11-2933 increased by a mean of 50-fold the cytotoxic effects of the anthracyclines and the Vinka alkaloids analyzed. A potentiation of Cisplatin activity was also observed (6.5-fold), whereas the Tiapamil analog did not significantly modify the antiproliferative activity of Bleomycin, Fluorouracil or Ara-C. Analysis of DX uptake and retention showed that in resistant cells RO11-2933 restored the intracellular DX content to levels comparable to those of sensitive A2780 cells, suggesting that the cytoplasmic membrane might represent a possible site of action of this compound. The results obtained indicate that RO11-2933 might represent an effective agent in combination with several anticancer drugs for the treatment of drug resistant ovarian carcinomas.

The role of drug sequence in therapeutic selectivity of the combination of 5-fluorouracil and cis-platin.

The therapeutic efficacy of 5-fluorouracil (FUra) and cis-dichlorodiamine-platinum (cis-DDP) in mice bearing transplantable leukemia and solid tumors was evaluated using different sequences of combination of these agents. The optimal sequence was cis-DDP administered 24 h after FUra. The administration of FUra at its maximally tolerated dose (MTD) followed 24 h later by low doses of cis-DDP yielded less toxicity and higher response rate against L1210 and colon 26 than the administration of these two agents in the opposite sequence or concurrently at the MTD. The sequence of administration of these two agents was not therapeutically important when the antitumor activity was evaluated against mice bearing lymphoma P388. These results indicate that the importance of sequencing of FUra and cis-DDP varies among different tumors. The biochemical basis for the therapeutic importance of sequencing in treatments with cis-DDP and FUra was investigated in mice bearing leukemia L1210 cells. While cis-DDP has no significant effects on the activity of thymidylate synthase (dTMP-S), the target enzyme for FUra action, recovery of dTMP-S inhibition following pretreatment with FUra was significantly delayed when cis-DDP was administered 12-24 h after the initial dose of FUra.

Plasma retinol levels and side effects following high-dose retinyl acetate in breast cancer patients.

Plasma retinol levels and toxicity were evaluated in thirteen metastatic breast cancer patients treated orally with high-dose (300,000 I.U./day) retinyl acetate in combination with oral tamoxifen. Following the first dose of the drug, there was a drop of plasma retinol concentrations followed by a recovery to the pre-treatment levels and by a further increase to reach a plateau six to eight hours after drug administration. During the first two months of treatment cumulative increase of plasma retinol was seen, and long-term systemic concentrations in the +50-60% range level were maintained by the treatment. The toxicity observed was acceptable and included gastrointestinal symptoms, skin toxicity and headache. These toxicities could be related to the long-term increase of retinol systemic concentrations. We concluded that the daily dose of 300,000 I.U. retinyl acetate can be administered to cancer patients over a period of several months, is well tolerated and yields a substantial increase of systemic retinol.

Plasma and tumor tissue pharmacology of high-dose intravenous leucovorin calcium in combination with fluorouracil in patients with advanced colorectal carcinoma.

Plasma pharmacokinetics of high-dose (500 mg/m2) leucovorin calcium (dl-5-formyltetrahydrofolic acid [dl-CF]) and fluorouracil (FUra) have been evaluated in patients with advanced colorectal cancer treated with the combination of FUra and dl-CF by two different intravenous (IV) schedules: (A) In patients with no prior chemotherapy, dl-CF was administered by a two-hour IV infusion and FUra by rapid IV injection one hour after the start of the dl-CF infusion and (B) in previously treated patients, dl-CF and FUra were administered by five-day continuous IV infusion (CI). Following the two-hour infusion of dl-CF, mean peak plasma concentration and elimination half-life of I-5-formyltetrahydrofolic acid (I-CF) were 24 +/- 6 mumol/L and 0.8 +/- 0.1 hour, respectively. CI of dl-CF over five days yielded a mean steady-state plasma level of I-CF of only 1.2 +/- 0.5 mumol/L. Peak and steady-state plasma concentrations of the metabolite 5-methyl tetrahydrofolic acid were comparable in the two schedules (17 +/- 8 mumol/L for the two-hour infusion and 12 +/- 5 mumol/L for the CI). Areas under the concentration v time curve (AUC) of total reduced folates were significantly greater under conditions of CI: 89.0 v 16.7 mmol/L/min for the two-hour infusion. In tumor tissue, 5,10-methylenetetrahydrofolate increased eight-fold two to four hours following the two-hour infusion and two-fold during the CI of dl-CF and FUra. Inhibition of thymidylate synthase (dTMP-S) by the two-hour and CI infusion schedules were 66% v 39%, respectively. The observed differences in the intracellular dTMP-S folate cofactor pools and the degree of inhibition of dTMP-S achieved in patients treated by two different schedules may be due to differences in the biochemical properties and/or to differences in the modulation of FUra metabolism by folate of tumor tissues obtained from newly diagnosed and previously treated patients.

A phase II trial of 5-fluorouracil and high-dose intravenous leucovorin in gastric carcinoma.

Twenty-eight patients with advanced measurable gastric carcinoma were treated with leucovorin (dl-CF; folinic acid; dl-5-formyltetrahydrofolic acid) 500 mg/m2 administered as a two-hour infusion and 5-fluorouracil (5-FU) 600 mg/m2 intravenous (IV) push midinfusion. Treatment was administered weekly for 6 weeks followed by a 2-week rest. Twenty-five patients were evaluable for response. Twelve of them had received previous combination chemotherapy that included 5-FU. Median age was 59 years, and median Eastern Cooperative Oncology Group (ECOG) performance status was 2. Three patients had partial responses and two of them had been treated previously with 5-FU. Twelve patients had stable disease. Five of these patients had subjective improvement with improved performance status and/or decreased dysphagia. The 95% confidence interval for response is 3% to 32%. Median survival time for all 28 patients enrolled in the study was 22 weeks. Toxicity was moderate and consisted primarily of diarrhea. Myelosuppression, skin rash, and increased lacrimation also occurred. Plasma concentrations of the active reduced folates, I-CF and 5-methyltetrahydrofolic acid (5-CH3FH4), were greater than the 10 mumol/L levels that potentiate 5-FU activity in in vitro models, for more than four hours in all five patients in whom pharmacokinetics were studied. 5-FU and high-dose dl-CF has activity in patients with gastric carcinoma including patients who had previously progressed on 5-FU-containing combinations. Further study in a larger patient population is necessary to determine the usefulness of this regimen in gastric carcinoma.

Role of administration route in the therapeutic efficacy of doxifluridine.

Effect of drug administration route on the therapeutic efficacy of the 5-fluorouracil (FUra) analogue doxifluridine [(5'-dFUrd); 5'-deoxy-5-fluorouridine] was investigated in Fischer CDF rats bearing a chemically induced transplantable colon carcinoma sensitive to fluoropyrimidines. The antitumor activities of 5'-dFUrd and of its parent drug FUra were evaluated after 7 days of continuous administration (by iv infusion, iv push, or po route) of doses ranging from 125 to 750 mg 5'-dFUrd/kg/day and from 12.5 to 55 mg FUra/kg/day. At the maximally tolerated dose, 5'-dFUrd (500 mg/kg/day) and FUra (25-35 mg/kd/day) were equally effective in producing cures when treatments were performed by either continuous iv infusion or iv push. 5'-dFUrd was more effective than FUra when these agents were administered orally (82% cures for 5'-dFUrd vs. 30% cures for FUra). Concentrations of 5'-dFUrd and its metabolite FUra in the blood and urine of normal and tumor-bearing rats were determined by high-performance liquid chromatography following administration of 500 mg 5'-dFUrd/kg. Pharmacokinetic studies indicated that at comparable antitumor activity, systemic exposures to FUra derived from 500 mg 5'-dFUrd/kg administered by iv push, orally, or continuous iv infusion were 3.5 +/- 1.0, 3.2 +/- 1.1, and 1.5 +/- 0.3 mM X min, respectively. Antitumor activity and pharmacokinetic results obtained in this model system indicated that 5'-dFUrd is an active agent that can produce cures regardless of the route of administration employed and among the three methods of drug administration tested, comparable tumor-free survival can be achieved by continuous iv infusion of 5'-dFUrd with the concomitant lowest systemic exposure to the cytotoxic metabolite FUra.

Biochemical and pharmacologic basis for potentiation of 5-fluorouracil action by leucovorin.

In vitro and in vivo studies have been carried out in mouse and human tumors to investigate the biochemical and pharmacologic basis for the selectivity of 5-fluorouracil (FUra) action. Combination chemotherapy with FUra and thymidine was performed to determine the therapeutic relevance of 5-fluorouridine triphosphate (FUTP) incorporation into RNA. The results of these studies indicate that modulation of FUra cytotoxicity by deoxythymidine (dThd) did occur but failed to produce any significant therapeutic advantages in patients with advanced colorectal cancer. Modulation of FUra bioactivation via the deoxyribonucleotide pathway by coadministration of high-dose folinic acid resulted in enhanced therapeutic response rate of gastrointestinal tumor patients. This manuscript summarizes the preclinical and clinical findings on the metabolic modulation of FUra activity by dThd and folinic acid.

Biologic modulation of 5-fluorouracil with high-dose leucovorin and combination chemotherapy of 5-fluorouracil and cisplatin in metastatic colorectal adenocarcinoma.

The data from an ongoing 3-arm prospective study of 72 patients with advanced colorectal carcinoma is presented. The 3 regimens are as follows: Regime 1 (every 4 weeks)--5-fluorouracil (FUra) (450 mg/m2 iv bolus daily for 5 days, then 200 mg/m2 iv bolus every other day for 6 doses); regime 2 (every week for 4 weeks, then every other week)--methotrexate (MTX) (50 mg/m2 in a 4-hour infusion) followed by FUra (600 mg/m2 iv bolus); regime 3 (weekly for 6 weeks followed by a 2-week rest period)--D,L-leucovorin (D,L-CF) (500 mg/m2 in a 2-hour infusion) with FUra (600 mg/m2 iv bolus) 1 hour after the D,L-CF infusion began. All monitoring lesions except lung were documented by tissue biopsy. Thirteen of 18 patients in the FUra + D,L-CF arm were evaluable for response. Six of the 13 patients (46%) have had a partial response. The duration of the 6 responses has been 11, 8, 7, 4, 3 and 3 months. In patients with liver metastases as the monitoring lesion, a dramatic improvement in liver function tests has been seen during the first 2 courses (12 weeks) of treatment, but this was not sustained. The toxicity of FUra + D,L-CF was predominantly gastrointestinal; unlike with FUra alone, myelosuppression was not predominant.

A phase II trial of 5-fluorouracil and high-dose leucovorin in gastric carcinoma and a phase I trial of intraperitoneal 5-fluorouracil and leucovorin.

Twenty-five patients with advanced measurable gastric carcinoma were treated with D,L-leucovorin (CF) (500 mg/m2) administered as a 2-hour infusion and FUra (600 mg/m2) iv push midinfusion. Patients were treated weekly for 6 weeks followed by a 2-week rest. Median age was 57 (range 32 to 82). Median Eastern Cooperative Oncology Group (ECOG) performance status was 2 (range 0 to 4). Thirteen patients had progressed on previous combination chemotherapy that included FUra. At the time of this report, 19 patients were evaluable for response: 3 patients had partial responses, 8 had stable disease, and 8 progressed (but 3 of these received only 3 or fewer treatments before early disease-related death). Two of the responders were previously treated with FUra. Four patients were too early to evaluate. Measurable responses of greater than 50% were seen in bone, liver, lung, and an abdominal mass. Diarrhea occurred in 9 patients and FUra dose reduction was necessary in 8 of them. Other toxicities included lacrimation, rash, nausea, and mucositis. One toxic death occurred. Nine patients with gastrointestinal tumors confined primarily to the intra-abdominal space were treated with ip FUra in escalating doses (2 mM to 4 mM) in combination with D,L-CF in a 2-liter volume, either by 8 consecutive 4-hour dwells (7 patients) or once daily for 5 days (2 patients). The D,L-CF dose was 20.8 microM except for the first day of the 5-day schedule when it was 104 microM. Toxicity included leukopenia, mucositis, nausea and vomiting, skin rash, and abdominal pain. Three episodes of peritonitis resolved with antibiotics.(ABSTRACT TRUNCATED AT 250 WORDS)

Phase I and pharmacologic studies of intraperitoneal leucovorin and 5-fluorouracil in patients with advanced cancer.

Many patients with gastrointestinal (GI) tumors develop extensive peritoneal and serosal metastasis and/or malignant ascites which respond poorly to available treatments. Twelve patients with tumors confined primarily to the intraabdominal cavity were treated with intraperitoneal (IP) 5-fluorouracil (5-FU) in escalating concentrations (2 to 4 mmol/L) in combination with leucovorin (dl-5-formyltetrahydrofolic acid or folinic acid; dl-CF) in a 2-L volume, either by eight consecutive four-hour dwells or once daily for five days. CF dose was 20.8 or 104 mumol/L. Nine of the patients had pancreatic carcinoma, one had stomach carcinoma, and two had hepatobiliary neoplasms. Median age was 62.5 years and median Eastern Cooperative Oncology Group (ECOG) performance status was 3. Toxicity included mucositis, diarrhea, nausea and vomiting, leucopenia, skin rash, and abdominal pain, and was similar to that previously reported for IP 5-FU used as a single agent. Four episodes of peritonitis occurred, but all patients responded to antibiotics. At the 20.8 mumol/L dose, dl-CF concentration in the peritoneal fluid declined from 10.4 +/- 3.0 3.0 mumol/L at one hour to 4.9 +/- 2.2 mumol/L at four hours, corresponding to a mean absorption half-life of 127 +/- 49 minutes and a mean peritoneal clearance of 13.0 +/- 4.5 mL/min. Decline was biphasic in all but five of the 19 exchanges evaluated. The levels of l-CF (biologically active isomer of dl-CF) were 2.8 +/- 2.5 mumol/L after 60 minutes and 1.2 +/- 0.7 mumol/L after four hours. The peritoneal area under the concentration v time curve (AUC) for 5-FU increased proportionally with dose. For example, the AUC at 2.0 and 3.5 mmol/L was 129 +/- 25 and 201 +/- 23 mmol/L X minute, respectively. However, the maximal peritoneal to plasma AUC ratio was 461 at the 2 mmol/L dose, but decreased with increasing doses as systemic clearance decreased. This regimen was well tolerated in patients with advanced cancer, but must be evaluated further to determine its clinical efficacy.

Comparative distribution of free doxorubicin and poly-L-aspartic acid linked doxorubicin in MS-2 sarcoma bearing mice.

The plasma and tissue distribution of doxorubicin-poly-L-aspartic acid (DX-PAA) and doxorubicin (DX) at equitoxic doses have been studied by a fluorescence assay in tumor bearing mice following administration of a single i.v. bolus injection. A relatively short distribution phase followed by a slow elimination phase characterized the DX-PAA plasma disappearence: at 48 hr after the treatment the conjugate was still detected in plasma. The plasma under the concentration vs. time curve (AUC) of drug equivalents following free DX administration resulted 2.6 times higher than the plasma AUC of free equivalents produced by DX-PAA treatment. In lung, liver and spleen the DX-PAA was accumulated in high concentrations. Low amount of DX equivalents were found in the heart following the conjugate administration: after 2 hr only traces of free anthracycline equivalents were detectable. On the contrary, drug equivalents following free DX treatment remained evaluable in the heart up to 24 hr from the drug administration. No significative differences were observed in the tumor AUC of free DX equivalents produced by free or polymer-linked DX. These data suggest that DX-PAA might act as a depot system slowly releasing the cytotoxic agent. Furthermore the observed accumulation of the conjugate and free DX equivalents in the lung and in the liver suggest a possible therapeutic advantages of DX-PAA in tumors with potential metastasis in these organs.

Timed sequential chemotherapy following drug-induced kinetic recruitment in refractory ovarian cancer.

Kinetic recruitment of cancer cells can seldom be monitored in human solid tumors. Repeated tumor sampling in ascitic ovarian cancer has been exploited to study tumor cell kinetic recruitment following treatment with the alkylating agent iphosphamide (IFX). The treatment schedule of the study was designed to administer the antimetabolic agents MTX-5FU at the time of the recruitment peak. Kinetic studies by the labelling index (LI) assay could be performed during and after the IFX treatment in four out of eight patients because of sampling difficulties. Experimental results showed that the IFX effectiveness reduced the proliferating cells, followed by cell kinetic recruitment from the resting pool. The antimetabolic treatment in concomitance with the proliferative peak (day 12) has been reduced with respect to the original schedule due to the heavy leukopenia occurring to the patients. It is likely that the reduced drug dosage might have contributed to the poor clinical response. However, the recruited cells exhibited an increased in vitro chemosensitivity to adriamycin in comparison to tumor cells studied before the IFX treatment.

In vitro hematoporphyrin (Hpd) inhibitory effects on some immunological assays.

Hematoporphyrin derivative (Hpd) is a fluorescent dye that is preferentially incorporated by tissues with a high mitotic index, such as tumor cells and blast cells. A cytotoxic effect is produced following light activation. Previous studies have shown a long lasting reversible inhibition of DNA synthesis in Hpd-treated cells that failed to stimulate allogeneic lymphocytes in either primary or in secondary MLR. In this study we report Hpd inhibitory effects on some immunological assays in vitro. Treatment with Hpd of cytotoxic effector cells resulted in inhibition of their lytic activity likely dependent on the loss of binding to target cells. In the same way Hpd treatment inactivated the lytic activity of NK cells. In contrast Hpd-treatment of target cells did not modify the above immunological reactions. Moreover Con A agglutinability, antibody dependent capping as well as E-rosettes were inhibited following an Hpd treatment of relevant cells. Since normal susceptibility to humoral and cell mediated lysis was exhibited by Hpd-treated cells it is unlikely that cell surface molecules were damaged. An inhibitory effect exerted by an Hpd treatment on cell surface movements might explain these findings.