Effects of secretory products of breast cancer cells on osteoblast-like cells

Summary The pathogenesis of breast cancer-induced osteolysis remains largely unknown. To evaluate the potential role of osteoblasts as target cells during this process, we incubated SaOS-2 human osteoblast-like cells (OBL) with culture media conditioned by proliferative (PM, Proliferation Media) or confluent (CfM, Confluence Media) MCF-7 human breast cancer cells. CfM decreased the growth of OBL by 26% (P < 0.01) while PM was without significant effect on this parameter. In contrast, both PM and CfM obtained from MCF-7 cultures increased the cyclic AMP (cAMP) response of OBL to the osteolytic agents PTH (10^–8 M) and PTH-related peptide (PTHrP, 10^–8 M) by a factor of about 3 (P < 0.001), and to prostaglandin E₂ (PGE₂, 10^–6 M) by a factor of about 2 (P < 0.01). No significant modulation of OBL growth or sensitivity to PTH, PTHrP, or PGE2 was induced by media obtained from HBL-100 non-malignant immortalized breast epithelial cell cultures. 17-estradiol (E₂, 10^–8 M) and the antiestrogen tamoxifen (Tam, 10^–7 M) added for 48 h to MCF-7 cultures before collecting conditioned media attenuated and potentiated, respectively, the PM- but not the CfM-induced increase in the response of OBL to PTH or PTHrP. Along the same line, the addition to MCF-7 conditioned media of a polyclonal anti-transforming growth factor- (TGF-) antibody attenuated by about 25% (P < 0.01) the PM-induced increase in OBL response to PTH and PTHrP while abrogating the modulatory effects of E₂ and Tam on that response. Together, our results indicate that MCF-7 breast cancer cells secrete factors which inhibit the growth of OBL and increase their sensitivity to various osteolytic agents. TGF- was only partly responsible for these effects, and accounts for their modulation by E₂ and Tam. The identification of other osteoblast-modulatory factor(s) should contribute to a better understanding and treatment of breast cancer-induced osteolysis.     

Phase I/II tolerability/pharmacokinetic study with one-hour intravenous infusion of doxifluiridine (5′-dFUrd) 3 g/m2 VS 5 g/m2 QD x 5 per month

Summary Eighteen patients with advanced solid cancer were treated with daily 5-dFUrd infusions given over 1 h on days 1–5 of a 4-week cycle. Nine patients received 3 g/m² 5-dFUrd daily and another nine patients 5 g/m². One patient on 5 g/m² 5-dFUrd was not fully evaluable for tolerability due to early death (progressive disease) 4 weeks after the first cycle. A total of 48 cycles was given. The gastrointestinal and hematological toxicity was generally mild (grade 1–2). Central neurotoxicity (ataxia, unsteadiness, diplopia, dysarthria, sometimes confusion) was observed in 7 of 8 patients on 5 g/m² 5-dFUrd leading to premature discontinuation of treatment in 3 patients (after 2 cycles). Only 3 of the 9 patients in the 3 g/m² group had slight signs of cerebellopathy. Typically, the reversible neurological side effects started at the end of the 2nd week of a cycle. The serum elimination kinetics of 5-dEUrd and its metabolites 5-FU and 5-dFUH₂ have been investigated in the serum and showed very low intra- and interindividual variations. Peak concentrations of the 5-dFUrd at the end of the infusion approximated 500 mol/l and 1000 mol/l for the 3 g/m² and 5 g/m² group, respectively. The peak of the serum 5-FU was reached at the same time, the ratio 5-FU/5-dFUrd being around 10%. The elimination half-life time for 5-FU was protracted by a factor of 2–3 compared with the direct injection of 5-FU.Monthly infusion of 5-dFUrd 5 mg/m² per day on days 1–5 lead to an unacceptable frequency and degree of neurological toxicity. Similar infusions of 5-dFUrd 3 g/m² per day on days 1–5 were well tolerated.     

Phase II study of cisplatin and 5‐fluorouracil in previously treated metastatic breast cancer: an Eastern Cooperative Oncology Group study (PA 185)

Purpose: The present study was conducted to investigate the efficacy and toxicity of a cisplatin and 5fluorouracil (5FU) combination in previously treated advanced breast cancer.Methods: Thirtysix women with recurrent metastatic breast cancer were entered on a phase II study of 5FU 1000mg/m²/day given intravenously as a continuous infusion on days 1–3 and cisplatin 30mg/m²/day given intravenously over 1h on days 2–4, repeated every 21 days. All subjects had received one previous chemotherapy regimen for metastatic disease and either progressed during treatment or relapsed after responding to previous chemotherapy. Fourteen patients had also received previous adjuvant chemotherapy, 17 patients had previous radiation therapy, and 29 patients had previous hormonal therapy.Results: Among 32 responseevaluable patients, there were 10 partial remissions (31%) and 1 complete remission (3%), with an overall objective response rate of 34%. Median duration of response was 4 months. Median survival was 10.5 months for responders and 9.5 months for the entire group. Toxicity was mild to moderate in most patients. Overall twelve patients experienced grade 3 toxicity (10 hematologic, 1 mucositis, and 2 nausea). There were no grade 4 or 5 toxicities.Conclusion: Infusional cisplatin and 5FU is a well tolerated and active regimen in women with previously treated advanced breast cancer.     

A Critical Examination of the Results from the Harvard-MIT NCT Program Phase I Clinical Trial of Neutron Capture Therapy for Intracranial Disease

A phase I trial was designed to evaluate normal tissue tolerance to neutron capture therapy (NCT); tumor response was also followed as a secondary endpoint. Between July 1996 and May 1999, 24 subjects were entered into a phase I trial evaluating cranial NCT in subjects with primary or metastatic brain tumors. Two subjects were excluded due to a decline in their performance status and 22 subjects were irradiated at the MIT Nuclear Reactor Laboratory. The median age was 56 years (range 24–78). All subjects had a pathologically confirmed diagnosis of either glioblastoma (20) or melanoma (2) and a Karnofsky of 70 or higher. Neutron irradiation was delivered with a 15cm diameter epithermal beam. Treatment plans varied from 1 to 3 fields depending upon the size and location of the tumor. The ¹⁰B carrier, L-p-boronophenylalanine-fructose (BPA-f), was infused through a central venous catheter at doses of 250mgkg^–1 over 1h (10 subjects), 300mgkg^–1 over 1.5h (two subjects), or 350mgkg^–1 over 1.5–2h (10 subjects). The pharmacokinetic profile of ¹⁰B in blood was very reproducible and permitted a predictive model to be developed. Cranial NCT can be delivered at doses high enough to exhibit a clinical response with an acceptable level of toxicity. Acute toxicity was primarily associated with increased intracranial pressure; late pulmonary effects were seen in two subjects. Factors such as average brain dose, tumor volume, and skin, mucosa, and lung dose may have a greater impact on tolerance than peak dose alone. Two subjects exhibited a complete radiographic response and 13 of 17 evaluable subjects had a measurable reduction in enhanced tumor volume following NCT.     

Increased risk of second cancers following breast cancer: Role of the initial treatment

Objectives and methods.The risk of second primary malignancies (SMN) was studied in a cohort of 4,416 one-year survivors of a breast cancer. The role of the menopausal status and of the initial treatment modalities (surgery, radiotherapy, and chemotherapy) was investigated. Results.Excluding second primary breast cancer and non-melanoma skin cancer, a total of 193 (4.4%) patients developed a SMN between 1973 and 1992, compared with 136 expected (Standardised Incidence Ratio, SIR=1.4, 95% CI (1.2–1.6)). No trend towards either an increase or a decrease was noted in the SIR with time after treatment (p=0.2). The greatest increase in the relative risk concerned soft tissue cancers (SIR=13.0, 95% CI: 6.8–22.3), followed by leukaemia (SIR=3.1, 95% CI: 1.7–5.0), melanoma (SIR = 2.7, 95% CI: 1.4–4.8), kidney (SIR=2.5, 95% CI: 1.2–4.5), ovary (SIR=2.0, 95% CI: 1.2–3.1) and uterine tumours (SIR=1.9, 95% CI: 1.4–2.5). The SIR was 3.0 (95% CI 1.8–4.7) in women under 40 at the time of the breast cancer, 1.9 (95% CI : 1.4 – 2.4) in those aged 40–49 and 1.2 (95% CI 1.0–1.4) in those aged 50 or more. In the 2,514 women who had received radiotherapy as initial treatment without chemotherapy, the SIR for all SMN was 1.6 (95% CI: 1.1–2.3) fold higher than in those who had not received radiotherapy as initial treatment. Conclusion.In conclusion, this study confirms the increased risk of second malignancies in women treated for a breast cancer, and particularly in those who were younger at the time of treatment for breast cancer. Our results also suggest that radiotherapy may play a role in the onset of these second lesions.     

Pharmacokinetics and pharmacodynamics of the aromatase inhibitor 3-ethyl-3-(4-pyridyl)piperidine-2,6-dione in patients with postmenopausal breast cancer

Summary The pyridylglutarimide 3-ethyl-3-(4-pyridyl)-piperidine-2,6-dione (PyG) is a novel inhibitor of aromatase that was shown to cause effective suppression of plasma oestradiol levels in postmenopausal patients. In four patients receiving oral doses of PyG (500 mg) twice daily for 3–4 days, oestradiol levels fell to 31.1%±6.3% of baseline values within 48 h and remained suppressed during treatment. Of a further six patients who received oral PyG (1 g) as a single dose, five had quantifiable oestradiol levels. Oestradiol suppression was sustained for 36 h and recovery correlated with a fall of PyG concentrations below a threshold value of ca. 2 g/ml. The pharmacokinetics of PyG were non-linear and, when fitted to the integrated Michaelis-Menten equation, yielded good parameter estimates forC _o (21.7±1.82 g/ml),K _m (2.66±0.68 g/ml) and V_max (0.86±0.06 g ml^–1 h^–1). On subsequent repeated dosing with PyG, both theK _m (4.31±0.48 g/ml) and the V_max (1.83±0.13 g ml^–1 h^–1) values increased and recovery from oestradiol suppression was more rapid, indicating that PyG induces its own metabolism.Abbreviations PyG 3-ethyl-3-(4-pyridyl)piperidine-2,6-dione - AG aminoglutethimide - CSCC cholesterol side-chain cleavage - HPLC high-performance liquid chromatography - AUC area under the concentration versus time curve This study was supported in part by grants to the Institute of Cancer Research (Royal Cancer Hospital) from the Cancer Research Campaign and Medical Research Council     

Disposition and metabolism of bruceantin in the mouse

Summary A microbiologic assay of the agar diffusion type, employing a strain of yeast tentatively identified as Candida macedoniensis, was developed to study the disposition, excretion, and metabolism of the antitumor agent bruceantin (BN; NSC 165563) in the mouse. Bioautographic studies showed the assay to be specific for BN. Normal and tumor-bearing male BDFl mice were studied. Tumor-bearing mice were implanted sc with 10 ⁶ L1210 ascites cells and held for 7 days prior to dosing. Average tumor weight was 307 mg and advanced generalized disease was evident. Three groups of 5 or 10 mice were injected iv with BN (1.5 mg/kg; approx. LD₁₀). At various times after injection, blood, tissues, urine, and feces were obtained and extracted with chloroform to recover BN. Recovery of BN was in the range of 91 to 121%. Disposition and excretion of BN were similar for normal and tumor-bearing mice. Decay of BN in blood was biphasic with -phase half-lives of 5 to 6 min. Estimated half-lives for the -phase were possibly >0.5 day. Average zero time intercepts for -and -phases were 550 and 51 ng/ml respectively. Higher levels of BN were found in lung, pancreas, intestine, and spleen (1–6 g/g) than in liver, kidney, and tumor (0.3–0.5 g/g) after 15 min. Concentrations of BN in brain and peritoneal fat were below detectable limits (0.1 g/g tissue). Urine and fecal excretion of BN accounted for 2% of the dose after 24 h. In vitro metabolism studies using a postmitochondrial microsome fraction of liver, lung, and kidney suggest that bruceantin is inactivated by an NADPH-dependent enzyme present in liver but not in lung or kidney.Supported by contract NO1-CM-87162 from the Division of Cancer Treatment, National Cancer Institute, National Institutes of Health, Department of Health, Education, and Welfare     

Irofulven Induces Apoptosis in Breast Cancer Cells Regardless of Caspase-3 Status*

Caspase-3 deficiency can limit the efficiency of pro-apoptotic anticancer treatments. Irofulven (hydroxymethylacylfulvene, HMAF, MGI 114, NSC 683863) is an antitumor drug, currently in a Phase III and multiple Phase II trials, which can differentiate between tumor and normal cells in apoptosis induction. This study investigated whether apoptosis induced by irofulven requires caspase-3. Irofulven action was compared in breast cancer cells differing in caspase-3 status: deficient MCF-7 cells and proficient MDA-MB-231 cells and in normal human mammary epithelial cells, HMEC. Irofulven induces significant, concentration and time-dependent apoptotic DNA fragmentation in breast cancer cell lines, regardless of caspase-3 status. After 12, 24 and 48h incubation at 1M irofulven ( 3×GI₅₀), fragmented DNA comprised 3.7, 14.1 and 34.6% and 8.4, 12.6 and 20.3% of total DNA in MCF-7 and MDA-MB-231 cells, respectively. Cell viability (trypan blue exclusion) remained largely unaffected during the first 24h but decreased markedly after 48h, indicating secondary necrosis. Net losses in cell numbers were apparent at 48h. Normal HMEC cells were refractory to 1M drug with only 3–9% fragmented DNA after 12–48h, although apoptosis was observed at drug levels >3M. The broad-spectrum caspase inhibitor Z-VAD-fmk inhibited irofulven-induced apoptosis of all cell lines at 20M with nearly complete abrogation of apoptosis at 100M. Irofulven treatment resulted in marginal caspase-3 processing in MDA-MB-231 and HMEC cells. These results indicate that whereas the caspase cascade mediates irofulven- induced apoptosis, caspase-3 is dispensable (supported by NIH CA70091 and CA78706).     

A phase I trial of continuous infusion VP16-213 (Etoposide)

Summary Since there appears to be a schedule dose relationship for VP16-213, the current dose seeking study of 5 day continuous infusion was initiated. Patients not candidates for other treatments were started at 75 mg/m²/dayx5. Eight patients had prior chemotherapy, eight had radiotherapy plus chemotherapy and one patient had prior interferon. The median age was 53 (range 23–65) and the median performance status was 60 (range 50–90). Seventeen patients received 20 courses; two at 75 mg/m²/day, seven at 100 mg/m²/day, ten at 125 mg/m²/day, and six at 150 mg/m²/day. The major toxicity was hematologic and median WBC count nadirs (ranges) were respectively: 3.5 (2.3–4.7)x10³/l, 1.6 (0.2–3.4)x10³/l, 2.4 (0.1–3.6)x10³/l, 0.4(<0.1–0.7)10³/l. Platelet count nadirs were respectively: 150, 78 (20–189), 138 (26–326), 16 (9–88)x10³/l. The median days to WBC nadir and recovery and did not vary with dose and were 15 (9–21) and 24 (19–38) respectively. Median days to platelet count nadir were 12 (10–29) and recovery 24 (20–38) and did not vary with dose. Non-hematologic toxicities included mild nausea and vomiting, mild mucositis on six courses, diarrhea with two courses and fever during granulocytopenia during seven courses. Three patients manifested evidence of myocardial disease two with infarction and one with congestive failure during treatment. Two patients showed objective evidence of tumor regression, one patient with seminoma and one patient with renal cell carcinoma. The latter response was short. The current studies demonstrate that high dose continuous infusion VP16-213 is tolerable with acceptable toxicity using doses up to 125 mg/m²/day (625 mg/m² over 5 days).This investigation was supported in part by PHS grant number 1P50CA32107-1 Awarded by the National Cancer Institute, DHHS     

Treatment of advanced breast cancer with gemcitabine and vinorelbine plus human granulocyte colony‐stimulating factor

Purpose. A phase II trial was performed to investigate the efficacy and tolerance of gemcitabine, vinorelbine, and recombinant human granulocyte colonystimulating factor (GCSF) in advanced breast cancer. Patients and methods. Between April 96 and August 97, 60 patients entered this trial. Fortyfive patients were previously untreated and 15 patients had failed previous palliative chemotherapy with (n = 10) or without anthracyclines (n = 5). Therapy consisted of gemcitabine 1000mg/m² on days 1 + 15 + 21 and vinorelbine 40mg/m² on days 1 + 21, both diluted in 250ml saline and infused over 30min. GCSF was administered at 5g/kg/day subcutaneously from days 2–6 and 22–26. Courses were repeated every 5 weeks. Treatment was continued in case of response or stable disease until a total of six courses. Results. The overall response rate was 55.5% for patients who had not received prior palliative chemotherapy (95% confidence interval, 40%–70.3%), including 5 CR (11.1%) and 20 PR (44.4%) 12 patients (27%) had stable disease (SD), and 8 (18%) progressed. Secondline treatment with this regimen resulted in 6/15 (40%) objective remissions, 5 had SD, and 4 PD. The median time to progression was 9.5 months (range, 1.5–28) in previously untreated patients, and 7.0 months (range, 2–23) in those who had failed prior chemotherapy. After a median followup time of 15 months, 44 patients (73%) are still alive with metastatic disease. Myelosuppression was commonly observed, though WHO 3 and 4 neutropenia occured in only 9 (l5%) and 2 patients (3%), and was never complicated by septicaemia; grade 3 anemia was noted in 2 patients. Severe (WHO grade 3) nonhematologic toxicity was rarely observed, and included nausea/emesis in 3 and constipation in 2 patients. Conclusions. Our data suggest that gemcitabine and vinorelbine plus GCSF is an effective and tolerable first as well as secondline combination regimen for treatment of advanced breast cancer.     

Involvement of breast epithelial-stromal interactions in the regulation of protein tyrosine phosphatase-γ (PTPγ) mRNA expression by estrogenically active agents

Background. Protein tyrosine phosphatase (PTP) has been implicated as a tumor suppressor gene in kidney and lung cancers. Our previous results indicate that estradiol-17 (E₂)-induced suppression of PTP may play a role in mammary tumorigenesis. Zeranol (Z), a nonsteroidal growth promoter with estrogenic activity that is used by the US meat industry, induces estrogenic responses in primary cultured breast cells and breast cancer cell lines. Methods. PTP mRNA expression in human breast tissues and cells isolated from surgical specimens of mammoplasty and breast cancer patients were detected and quantified by RT-PCR. Immunohistochemical staining was used to localize PTP in human breast tissues. Breast epithelial and stromal cells were isolated and co-cultured to determine the involvement of cell–cell interaction in the regulation of PTP mRNA expression by E₂ and Z. Results. PTP mRNA expression was lower in cancerous than in normal breast tissues. Both E₂ and Z suppressed PTP mRNA levels in cultured normal breast tissues by 80%, but had a lesser effect in cultured epithelial cells isolated from normal breast tissues. In the co-culture system, both E₂ and Z suppressed PTP mRNA to a greater degree in epithelial cells than in stromal cells. In whole breast tissues, PTP was immunolocalized to the epithelium. Treatment with E₂ or Z diminished PTP staining indicating reductions in PTP at the protein level. Conclusions. The results indicate that both E₂ and Z regulate PTP expression in human breast and that epithelial–stromal cells interaction is important in the regulation of PTP expression by estrogenically active agents.     

Is salvage chemotherapy for metastatic breast cancer always effective and well tolerated? A phase II randomized trial of vinorelbine versus 5-fluorouracil plus leucovorin versus combination of mitoxantrone, 5-fluorouracil plus leucovorin

Metastatic breast cancer remains an incurable disease and the median overall survival has not significantly improved over the past two decades. Aims of the present randomized phase II trial were to analyse activity and toxicity of chemotherapies with single agent or with combination regimens in previously treated patients with advanced breast cancer. Ninety-nine eligible patients were randomized to receive the following chemotherapies: Arm A – 30mg/m² i.v. weekly; Arm B – leucovorin 100mg/m² i.v. followed by 5-fluorouracil 370mg/m² i.v. days 15, q 28days; Arm C – mitoxantrone 12mg/m² i.v. only day 1+leucovorin 100mg/m² i.v. followed by 5-fluorouracil 370mg/m² i.v. days 13, q 28days. Patients characteristics are comparable in the three groups. The median number of chemotherapy courses administered was 7, 6 and 5 in arm A, B and C, respectively. Objective responses were 24%, 30% and 21% and the median duration of responses were 2, 2.5 and 5.5 months in the arm A, B and C, respectively. Median overall survivals were 9.5, 9 and 9 months in the three arms. No difference was noted comparing the survivals of responding or non responding patients. General toxicity was not mild, with 27.5% of patients experiencing WHO grade 3–4 toxicities.Our results are similar in the three groups of patients and comparable to those reported by other authors. Chemotherapy applied to patients with second or subsequent recurrence allow objective responses in a small percentage of patients. Moreover responders have a negligible prolongation of survival.     

Epirubicin and doxorubicin comparative metabolism and pharmacokinetics

Summary The pharmacokinetics and metabolism of doxorubicin (DX) and epirubicin (epiDX) were investigated in eight cancer patients who received 60 mg/m² of both drugs independently by intravenous (i.v.) bolus at 3-week intervals according to a balanced cross-over design. Unchanged DX and epiDX plasma levels followed a triexponential decay. Half-lives (t/2) of the three decay phases were longer for DX (t/2: 4.8 vs. 3 min; t/2 2.57 h vs. 1.09 h; t/2 48.4 vs. 31.2 h). According to a model-independent analysis, the different plasma disposition kinetics of the two compounds appears to be related to a higher plasma clearance (PlCl) and to a lower mean residence time (MRT) of epiDX (PlCl: 75.0 l/h, range: 35.6–133.4 l/h; MRT: 31.6 h, range: 7.0–41.5 h;) compared to DX (PlCl: 56.8 l/h, range: 24.4–119.5; MRT: 45.6 h, range: 26.0–83.1 h). No statistically significant differences could be detected for the volume of distribution at steady state (Vss) (epiDX, 31.8 l/kg; DX, 33.3 l/kg). Metabolites common to both compounds were detected in plasma: the 13-dihydro derivatives doxorubicinol (DXol) and epirubicinol (epiDXol), together with monor amounts of four aglycones (7-deoxy adriamycinone, adriamycinone, 7-deoxy 13-dihydro adriamycinone, and 13-dihydro adriamycinone). Following epiDX administration, two additional major metabolites were detected: the glucuronic acid conjugates of epiDX (4-O--d-glucuronyl-4-epiDX) and epiDXol (4-O--d-glucuronyl 13-dihydro-4-epiDX). This additional detoxication route appears to account for the more efficient and faster elimination of epiDX than of DX. In the urine collected in the 6 days after treatment, 12.2% of the DX and 11.9% of the epiDX dose was excreted as unchanged drug and fluorescent metabolites. A comparable renal clearance was calculated for DX (4.7 l/h, range 1.4–7.0 l/h) and epiDX (4.4 l/h, range 1.7–7.0 l/h). One patient with hepatic metastates and abnormal bilirubin serum level had percutaneous biliary drainage because of extrahepatic obstruction. The elimination of both drugs was significantly impaired in this patient; nevertheless, elimination of epiDX was still more efficient and faster than that of DX (PlCl: 35.6 vs. 24.4 l/h; MRT: 39.0 vs. 83.1 h; t/2: 47 vs. 74 h). This patient's biliary excretion accounted for 35.4% of the epiDX dose and 18.2% of the DX dose.Supported in part by contract CNR, No. 85.02282.44 (Progetto Finalizzato Oncologia)     

Response of multicellular tumor spheroids to liposomes containing TNF-α

Summary This publication describes a new model to investigate the influence of tumor necrosis factor- (TNF-) on a three-dimensional glial cell aggregate under defined, standardized, reproducible conditions using the glioma cell line A 172.The cells are initially grown as normal monolayer culture until they reach a cell density of up to 1×10⁶. Subsequently they are grown as spheroids by the liquid overlay technique. Spheroids grown in this way were divided into ten groups of more than 50 cell aggregates. Three groups were coincubated with free TNF- in increasing dosages (100 ng/ml, 200 ng/ml and 1000 ng/ml); three groups were incubated with empty liposomes (0.2 mg/ml, 0.4 mg/ml and 2 mg/ml); three groups received liposomes which had been loaded with TNF-, and one group, which received no treatment, served as control.The diameter of the spheroids ranged from 80 m to 350 m. There was no significant difference in growth between the 3 groups treated with free TNF-. Comparing spheroids treated with TNF- with those which had been coincubated with empty liposomes, there was a significant difference (p<0.001) in growth, which correlated with the amount of liposomes. Similarly, free TNF- had a significantly (P<0.001) stronger growth-inhibiting effect as compared to liposomes loaded with TNF-. Comparing the groups treated with liposomes only to those treated with liposomes loaded with TNF-, the latter exhibited a more marked (although not significantly) growth-inhibiting effect.The preliminary conclusion is that the major growth-inhibiting effect seems to be mediated by the liposomes. This phenomenon is in agreement with results obtained in monolayer cultures.     

Neuroblastoma and parental occupation

Objectives: We evaluated parental occupation and the risk of neuroblastoma using data from a large case–control study conducted by the Children's Cancer Group and the Pediatric Oncology Group.Methods: We compared the distribution of 73 paternal and 57 maternal occupational groups among 504 newly diagnosed cases of neuroblastoma and individually matched controls obtained by telephone random digit dialing in the United States and Canada.Results: An increased risk of neuroblastoma was found for fathers employed as broadcast, telephone and dispatch operators (odds ratio [OR]=6.1; 95% confidence interval [CI]=0.7–50.9), electrical power installers and power plant operators (OR=2.7; CI=0.9–8.1), landscapers and groundskeepers (OR=2.3; CI=1.0–5.2), and painters (OR=2.1; CI=0.9–4.8). Elevated odds ratios were found for mothers employed as farmers and farm workers (OR=2.2; CI=0.6–8.8), florists and garden store workers (OR=2.4; CI=0.6–9.9), hairdressers and barbers (OR=2.8; CI=1.2–6.3), electric power installers and power plant operators, and sailors, fishers, and railroad workers. No increase in risk was found for other paternal occupations previously associated, including electricians, electrical equipment assemblers and repairers (OR=1.1; CI=0.6–2.0), or welders (OR=0.5; CI=0.1–1.6).Conclusion: The study reinforced some prior evidence of increased risks in electrical, farming and gardening, and painting occupations, but failed to confirm other previously reported associations. Further analyses of exposure to electromagnetic fields, metals, solvents, and pesticides are currently under way.     

Impact de l’accès à Internet dans la relation médecin/malade en cancérologie. Réflexions à partir d’un cas clinique.

Résumé: De plus en plus de patients atteints de cancer surfent sur Internet pour trouver des informations sur leur pathologie. Les caractéristques dInternet—facilité daccès, absence de médiation, encyclopédisme, profusion—bouleversent les modes daccès, de transmission et dutilisation du savoir médical. La relation médecin/patient en est bouleversée, plus spécialement dans le cas des maladies graves où le contenu émotif lié à la délivrance du diagnostic (et plus encore du pronostic) exacerbe les enjeux de la relation. À partir dun cas clinique particulièrement représentatif, cet article a pour objet de réfléchir à différentes problématiques:—quen est-il de linformation médicale aujourdhui?—lutilisation dInternet est-elle susceptible dentraver ladaptation psychique des patients confrontés au cancer?—quelles réflexions peut-on en tirer pour la pratique du cancérologue?     

The clinical pharmacokinetics of N-5-dimethyl-9-[(2-methoxy-4-methyl-sulfonylamino)phenylamino]-4-acridinecarboxamide (CI-921) in a phase 1 trial

Summary The pharmacokinetics of CI-921 were studied after 65 infusions over a 20-fold dose range (13–270 mg/m² per day) in 16 patients during a phase 1 trial. CI-921 was given by a 15 min infusion on three consecutive days.Plasma samples were collected after the first and third infusions, and urine, at 6 h intervals throughout the 3 days. CI-921 concentrations were measured by an HPLC method. Maximum plasma concentrations ranged from 3–86 mol/l.The plasma concentration-time disposition curves were mainly biphasic over the 24-h postinfusion period. There was no significant difference by the paired t-test between the C_max, AUC,CL, V_ss, MRT, t_1/2, or t_1/2 calculated for the first and third infusions. The means (range) of model-independent pharmacokinetic parameters were: CL, 158 (94–290) ml/h per kg; V_ss, 319 (219–614) ml/kg; MRT, 2.1 (1.1–3.5) h; t_1/2, 0.5 (0.2–1.1) h; and t_1/2, 2.6 (1.1–5.0) h. There was a strong linear correlation between the dose and the AUC and C_max,suggesting linear kinetics over this dose range. A very small amount (<1%) of the total dose was excreted as unchanged CI-921 in the urine, mostly in the 12-h postinfusion period.     

Beta-adrenergic receptors in DMBA-induced rat mammary tumors: Correlation with progesterone receptor and tumor growth

Summary In order to gain further knowledge about the potential role of catecholamines in mammary carcinoma, we have used the potent -adrenergic antagonist cyanopindolol (CYP) as iodinated ligand to characterize -adrenergic receptors in membranes prepared from mammary tumors induced by dimethylbenz(a)anthraene (DMBA) administration in the rat. The binding of [¹²⁵I]CYP to membrane preparations of DMBA-induced rat mammary tumors is rapid at room temperature, reaching half maximal specific binding at 30 min of incubation. Scatchard analysis of the data indicates that [¹²⁵I]CYP binds to a single class of high affinity sites (114 ± 2.1 fmoles/mg protein) at an apparent K_D value of 38.0 ± 0.3 pM. The order of potency of a series of agonists to compete for [¹²⁵I]CYP binding is consistent with interaction with a ₂-subtype receptor: zinterol > (–)isoproterenol > (–)epinephrine» (–)norepinephrine. In addition, the potency of a series of specific ₁, and ₂ synthetic compounds to displace [¹²⁵I]CYP in mammary tumors is similar to their potency in typical ₂-adrenergic tissues. The binding of [¹²⁵I]CYP to DMBA-induced rat mammary tumors shows a marked stereoselectivity, the (–)isomers of isoproterenol and propranolol being 150 and 80 times more potent, respectively, than their respective enantiomers. The autoradiographic localization of [¹²⁵I]CYP performed on frozen sections revealed the presence of specific -adrenergic receptors in all the malignant cells. Spontaneous mammary tumors of aging (18–22 months) female rats have high levels of -adrenergic receptors. Castration decreased the concentration of [¹²⁵I]CYP binding sites in DMBA-induced mammary tumors. A close correlation was observed between progressing, static, and regressing tumors after ovariectomy and -adrenergic receptor concentration. The presence of -adrenergic receptors in mammary tumors as well as the modulation of their level by ovarian hormones provides a mechanism for catecholaminergic influence in mammary cancer tissue.     

Potentiation of the antitumor activity of 5-trifluoromethyl-2′-deoxyuridine by the use of depot forms of the parent compound

Summary 5-Trifluoromethyl-2-deoxyuridine (CF₃dUrd), an antitumor agent, is known to be short-lived in human plasma. Since its rapid elimination from the blood-stream seems to have descouraged the clinical evaluation of this drug, we explored the potential use of masked derivatives of CF₃dUrd as depot forms of the parent compound. First, we observed that the toxicity of CF₃dUrd against HeLA cells in culture was 10⁴ times greater for a 24-h treatment as compared with a 1-h treatment at identical concentrations of the drug, which suggests the importance of using a prolonged treatment period. In fact, the divided dosing of CF₃dUrd to L1210-bearing mice was markedly more effective than its single administration. 5-O-Hexanoyl-,N ³-p-butylbenzoyl-, 5-O-benzyloxymethyl-, and 3-O-benzyl-CF₃dUrd were found to be effective in maitaining the CF₃dUrd concentration in plasma. The oral doses of these agents required to achieve 50% growth inhibition (ED₅₀) in mice bearing sarcoma 180 tumors were 19, 34, 10, and 13 mg kg^–1 day^–1, respectively, whereas that of CF₃dUrd was 63 mg kg^–1 day^–1. The ED₅₀ values for these compounds were inversely correlated with the residence time of CF₃dUrd in plasma. The therapeutic indices of these compounds, calculated as the dose producing a 50% inhibition of body-weight gain (IB₅₀) divided by the ED₅₀ value (1.89, 1,21, 1.40, and 2.15, respectively), were significantly higher than that of CF₃dUrd (0.78). Consequently, these depot forms of CF₃dUrd, particularly 3-O-benzyl-CF₃dUrd, are expected to be more useful than the parent compound as antitumor agents.Abbreviations CF₃dUrd 5-trifluoromethyl-2-deoxyuridine - CF₃dUMP 5-trifluoromethyl-2-deoxyuridine-5-monophospate - S180 sarcoma 180 - L1210 L1210 leukemia - k_el elimination rate constant - T1/2 half-life time - AUC area under the curve - ILS increase in life span - TS thymidylade synthase - FdUMP 5-fluoro-2-deoxyuridine-5 monophosphate - FUra 5-fluorouracil     

Induction of insulin‐like growth factor binding protein expression by ICI 182,780 in a tamoxifen‐resistant human breast cancer cell line

Earlier studies in our laboratory demonstrated that the steroidal antiestrogen ICI 182,780 is very effective in abolishing the tamoxifenresistant proliferation of MCF 7/523 cells [1]. In addition, preliminary binding studies showed that ICI 182,780 increased the binding of insulinlike growth factor (IGF)I to the MCF 7/523 cells, although this finding was not the result of an increase in the expression of the insulinlike growth factorI receptor (IGFIR). Hence, we reasoned that the inhibition of tamoxifenresistant cell growth by ICI 182,780 might have been due to increased expression of insulinlike growth factor binding proteins (IGFBPs).We observed the upregulation of noninsulinsuppressible IGFI binding in both the tamoxifensensitive MCF 7/521 cell line (1.5fold) and the tamoxifenresistant MCF 7/523 cell line (2.5fold) after 5 days of treatment with ICI 182,780 (10^–7 M) in serumfree medium, suggesting a role for cellassociated IGFBPs. Affinity crosslinking experiments confirmed the presence of an IGFI:IGFBP complex of approximately 38kDa in tamoxifen or ICI 182,780treated cells. Western ligand blots showed higher levels of a soluble 30kDa IGFBP in media conditioned by either of the subclones that had been treated with ICI 182,780, an effect consistently opposed by estrogen (E₂:10^–9 M). RTPCR showed higher levels of IGFBP5 mRNA than any of the other known IGFBPs, suggesting that this was the major IGFBP subtype. The protein was subsequently identified by Western immunoblotting as IGFBP5. In conclusion, we postulate that this may be a mechanism contributing to the greater potency of ICI 182,780 in the growth inhibition of the MCF 7/523, tamoxifenresistant cell line.