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Biomedical subjects

G Stoter

Publications and source records attributed to G Stoter.

At least 91 records · Page 5Linked to original sources

Sensitive determination of docetaxel in human plasma by liquid-liquid extraction and reversed-phase high-performance liquid chromatography.

A sensitive reversed-phase high-performance liquid chromatographic method has been developed and validated for the quantitative determination of docetaxel (I) in human plasma. The concentrations in plasma, for validation procedures spiked with known amounts of I, are read from calibration curves in the range of 10-20,000 ng/ml. The sample preparation involved a liquid-liquid extraction of 1000 microl of sample with a mixture of acetonitrile-n-butylchloride (1:4, v/v). The related compound paclitaxel (II) was used as internal standard. Chromatographic separations were performed an Inertsil ODS-80A column, with UV detection performed at 230 nm. The overall extraction recoveries were 84.3 and 90.0% for I and II, respectively. The lower limit of quantitation was 10 ng/ml, and the accuracy, within-run and between-run precisions at three tested concentrations fell within the generally accepted criteria for bioanalytical assays.

Aged↗

Bax upregulation is an early event in cisplatin-induced apoptosis in human testicular germ-cell tumor cell line NT2, as quantitated by flow cytometry.

Expression of the apoptosis-associated proteins Bcl-2 and Bax was quantitated by flow cytometry (FCM) in chemosensitive testicular germ-cell tumor NT2 cells, and the results were compared with those obtained by Western blotting. NT2 cells were incubated with cisplatin (3.1 microM for 2 h at 37 degrees C), and 24, 48, and 72 h later were analyzed for induction of apoptosis, and for modulation of the expression of cell death suppressing protein Bcl-2, as well as cell death promoting protein Bax. Apoptosis was quantitated by binding of annexin V conjugated with fluorescein isothiocyanate (FITC) to the cell membrane. Cisplatin-treatment induced apoptosis in NT2 cells. The apoptotic cell population increased in time, and at t = 72 h after drug incubation, about 90% of cells that were present in the cell culture were apoptotic. Subsequently, we determined the expression of the Bcl-2 and Bax proteins by FCM and Western blotting before and after drug treatment. NT2 cells had low constitutive expression levels of Bcl-2 and elevated constitutive expression levels of Bax protein, as determined by both methods. At t = 24 h and 48 h after drug treatment, no changes were observed in the expression of the Bcl-2 protein, as quantitated by FCM and Western blotting. Also, the expression of the Bax protein had not changed, based on Western blotting. However, FCM revealed that in a specific subpopulation of drug-treated NT2 cells, Bax expression was increased. On the basis of forward and perpendicular light-scatter this subpopulation, which consisted of large, early apoptotic, swollen cells with increased internal complexity, was sorted, and showed abundant Bax protein by FCM and Western blotting. Our results demonstrate that the chemosensitivity of NT2 cells is probably due to a low intrinsic threshold for drug-induced apoptosis that is accompanied by overexpression of the death-promoting Bax protein during the early stages of the apoptotic process. We conclude that FCM is superior to Western blotting for the detection of heterogeneous expression of Bax in a given cell population.

Apoptosis↗

The correlation of CA15.3 and TPS with tumor course in patients with metastatic breast cancer.

PURPOSE: This study was performed to determine the correlation of CA15.3 and TPS with disease course in patients with metastatic breast cancer. METHODS: Levels of CA15.3 and tissue polypeptide antigen using the M3 monoclonal antibody (TPS) were determined in the serum of 60 patients with metastatic breast cancer. CA15.3 and TPS were measured at two assay times. RESULTS: A change of more than 25% in the serum level of CA15.3 or TPS was highly correlated with tumor response. The association between response and change in marker levels was stronger for CA15.3 (P = 0.0001) than for TPS (P = 0.0005). Distinct mismatches between marker changes and the tumor response were observed for both CA15.3 and TPS. CONCLUSION: CA15.3 and TPS are useful in the determination of response to treatment. Because of observed disagreement, marker changes can only be regarded as indicative of disease course.

Adult↗

Tunnelled central venous catheters yield a low incidence of septicaemia in interleukin-2-treated patients.

A retrospective study on the incidence of catheter-related complications and catheter indwelling time (tCI) during treatment with continuous interleukin-2 (IL-2) infusion in patients with metastatic renal cell cancer, who were equipped with tunnelled central venous catheters (CVC). A group of 72 patients were treated with IL-2-based immunotherapy. Two induction treatment cycles of 35 days each were used. Treatment consisted of IL-2 as a continuous intravenous infusion (c.i.v.) with lymphokine-activated killer cells and interferon alpha intramuscularly. A tunnelled CVC was inserted at the start of treatment and was kept in place for the duration of the therapy or until the occurrence of complications. Out of 72 CVC, 30 (42%) functioned uneventfully for a median tCI of 64 days. In another 12 clinically uncomplicated cases (16%), catheter tips were positive in routine culture after a median tCI of 33 days. In 18 patients (25%), CVC-related infections were noted, including 8 (11%) local tunnel infections and 10 (14%) septic episodes. These complications occurred at a median tCI of 28 and 20 days respectively. In 15 (83%) of these 18 catheter infections, Staphylococcus aureus was isolated, whereas in the remaining 3 (17%) Staphylococcus epidermidis was found. Subclavian vein thrombosis was noted in 12 (17%) CVC at a median tCI of 31 days: 5 (36%) of these were diagnosed in the first 14 patients. This prompted us to administer prophylactic heparin 15,000 i.u. c.i.v. daily during IL-2 treatment. Thereafter the incidence of thrombosis dropped to 7 (12%) in the subsequent 58 CVC inserted (P = 0.03). In conclusion, in contrast to previous reports on the high incidence of CVC-related septicaemia and thrombosis, we observed a relatively low incidence of these complications, which we ascribe to the use of tunnelled catheters and prophylactic heparin.

Carcinoma, Renal Cell↗

A phase II study of weekly high-dose cisplatin combined with oral etoposide in advanced non-small-cell lung cancer.

As a dose-response relationship has been suggested for cisplatin, it appeared attractive to explore high-dose-intensity regimens in non-small-cell lung cancer. In a phase I study of weekly administration of cisplatin combined with oral etoposide we achieved a cisplatin dose intensity of 52.5-60 mg/m2 per week in most patients. We subsequently explored this regimen in advanced non-small-cell lung cancer. Patients were treated with cisplatin infused at 70 mg/m2 on days 1, 8, 15 and 29, 36, 43 in combination with oral etoposide given at 50 mg on days 1-15 and 29-43. Patients showing stable disease or a better response were continued on treatment with oral etoposide given at 50 mg/m2 per day on days 1-21 every 28 days for a maximum of four cycles. In all, 22 patients with stage III disease and 31 patients with stage IV disease entered the study. The median number of cisplatin administration was 6 per patient; 17 patients reached the planned cisplatin dose intensity of 60 mg/m2 per week, 11 patients achieved 52.5 mg/m2 per week, and 7 patients reached 47 mg/m2 per week. Overall, 11 of 21 stage III patients had a partial response [response rate 51%, 95% confidence interval (CI) 36-81%], as did 9 of 28 patients with stage IV disease (32%; 95% CI 15-49%). Toxicity was mainly hematologic, with leukocytopenia being the most frequent cause of treatment delay. Nephrotoxicity of grade 1 was observed in seven patients. Two patients developed clinical hearing loss. With this schedule a high median cisplatin dose intensity of 52.5-60 mg/m2 per week was reached. The 51% response rate achieved in stage III disease makes this schedule attractive for further exploration; however, it is not recommended for routine use in stage IV disease.

Administration, Oral↗

Pharmacokinetics of the multidrug-resistance-converting drug dexniguldipine and its pyridine metabolite M-1 in the plasma, tumor, and renal tissue of tumor-bearing Wag/Rij rats.

The pharmacokinetics of oral dexniguldipine, a new multidrug-resistance-modifying agent under clinical evaluation, and its pyridine metabolite M-1 were determined in plasma, tumor, and renal tissue in Wag/Rij rats bearing a multidrug-resistant CC531 colon adenocarcinoma tumor under the renal capsule. The pharmacokinetics were studied in four experiments. After a single administration of dexniguldipine (30 mg/kg), tumors and kidneys were collected after 5 (experiment 1), 24 (experiment 2), and 48 h (experiment 3). In the fourth experiment, dexniguldipine was given once daily for 3 consecutive days at a dose of 30 mg/kg. In all experiments, plasma samples were collected at regular intervals. The concentrations of dexniguldipine and M-1 could be determined in plasma in most of the rats at up to 32 h after drug administration. The area under the curve (AUC) of dexniguldipine and M-1 varied by a factor of 2-6 in the four experiments. High tumor-tissue concentrations of dexniguldipine were observed. The concentrations were highest in the multiple-dose experiment (2014 +/- 1005 ng/g tissue). High degrees of correlation (> 0.8) were established between the concentrations of dexniguldipine measured in plasma and tumor as well as renal tissue. Overall, tumor-tissue concentrations of M-1 comprised one-third of the dexniguldipine concentrations measured.

Adenocarcinoma↗

EORTC phase II study of daily oral linomide in metastatic renal cell carcinoma patients with good prognostic factors.

Following a previous EORTC GU-Group study, in which linomide showed some activity in poor prognosis patients, this study was initiated to determine the effect of linomide in more favourable patients. 35 patients with metastatic renal cell carcinoma with good prognostic factors, i.e. good performance status, prior nephrectomy, no prior systemic therapy, and no liver, bone or brain metastases, were treated with linomide, a quinoline derivative with immunomodulating properties, at a dose of 10 mg daily, after an initial dose escalation during the first 4 weeks of treatment. In 29 evaluable patients, no responses were observed (95% confidence interval 0-10%). Best overall response was no change in 9 patients, for a median duration of 4 months. Linomide in this schedule was poorly tolerated, with 17% (6 patients) of patients being withdrawn and 23% (8 patients) having dose reductions due to adverse events, mostly influenza-like symptoms of myalgia, arthralgia and fatigue. Several cases of pericarditis and neuropathy were observed. In spite of selection of favourable prognosis patients and an optimal daily dosing schedule, linomide was not an effective treatment in renal cell carcinoma. In view of toxicity and lack of efficacy, there is no rationale in further testing the drug in this disease.

Antineoplastic Agents↗

Differential modulation of cisplatin accumulation in leukocytes and tumor cell lines by the paclitaxel vehicle Cremophor EL.

BACKGROUND: Several clinical studies have shown that polychemotherapy with the taxanes paclitaxel or docetaxel preceded or followed by cisplatin is associated with important schedule-dependent differences in toxicities, such as leukocytopenia. In general, the pharmacokinetics of both drugs during the combined treatment are unaltered, suggesting that a pharmacodynamic interaction might have occurred. MATERIALS AND METHODS: In order to gain insight into this pharmacologic interaction, we performed in vitro drug accumulation studies using peripheral blood leukocytes and a panel of tumor and non-malignant cell lines with paclitaxel and docetaxel, as well as with their respective formulation vehicles Cremophor EL and Tween 80. RESULTS: Our results show a significant reduction in the intracellular cisplatin concentration in leukocytes of up to 42% in the presence of Cremophor EL and Tween 80 as compared to the control. This pharmacodynamic interaction of these surfactants with cisplatin seems to be specific for haematopoietic cells, and does not occur in solid tumor cells. CONCLUSION: The present data suggest that the pharmaceutical vehicles Cremophor EL and Tween 80 might contribute to the reduced cisplatin-associated myelotoxicity observed in the clinical combination chemotherapy studies with paclitaxel and docetaxel.

Antineoplastic Agents↗

Clinical characteristics of severe peripheral neuropathy induced by docetaxel (Taxotere).

BACKGROUND: Docetaxel, a semi-synthetic taxane may cause a usually mild sensory neuropathy. We describe the clinical characteristics of five patients who developed a more severe neuropathy following treatment with docetaxel. PATIENTS AND METHODS: All patients were treated in phase II studies with 100 mg/m2 docetaxel in three weekly cycles, without steroid administration. RESULTS: The clinical picture in these patients was dominated by a sensory neuropathy, but in one case severe weakness was present. Another patient developed Lhermitte's sign. Signs and symptoms are usually reversible after discontinuation of docetaxel administration, but in three patients symptoms worsened for some time after the end of treatment before improvement occurred. CONCLUSION: Severe docetaxel neuropathy may especially occur following treatment with cumulative dosage over 600 mg/m2; in patients treated with this dosage a moderate or severe neuropathy may not be rare.

Adult↗

The prognostic significance of expression of the multidrug resistance-associated protein (MRP) in primary breast cancer.

In the present study, we determined the frequency and intensity of MRP protein expression by monoclonal antibody immunohistochemistry in a series of 259 resected invasive primary breast carcinomas, and we evaluated MRP immunoreactivity in relation to patient and tumour characteristics, relapse-free (RFS) and overall survival (OS). The immunostaining was graded on a semiquantitative scale that ranged from (-) to ( ). Overall, 34% of the tumours were positive for anti-MRP antibody: 19% showed weak cytoplasmic staining (+), 14% had clear cytoplasmic staining (++) and only 1% of the tumours had a strong cytoplasmic as well as membranous staining ( ). MRP expression was not related to patient's age, menopausal status, tumour size, differentiation grade, oestrogen and progesterone receptor level or lymph node involvement. In an exploratory univariate analysis of all patients, only primary tumour size and number of lymph nodes involved were significantly associated with shortened RFS (P < 0.001 and P < 0.001 respectively) and OS (P = 0.02 and P < 0.001 respectively). In Cox univariate analysis for RFS in subgroups of patients stratified by menopausal status, tumour size, nodal status, adjuvant systemic therapy and oestrogen and progesterone receptor status, MRP expression was associated with increased risk for failure in patients with small tumours (T1), in node-negative patients and in node-positive patients who received adjuvant systemic chemotherapy with cyclophosphamide, methotrexate and 5-fluorouracil (CMF); the relative hazard rate (RHR) for relapse was increased in the presence of MRP, with RHR values with 95% confidence limits (CL) of 2.8 (1.2-6.9), 2.1 (1.0-4.2) and 2.8 (0.8-9.9) respectively. In analysis for OS, expression of MRP was also associated with increased risk for failure in patients with small tumours (T1) [RHR (95% CL) 2.3 (0.9-6.0)] and in node-positive patients who received adjuvant systemic chemotherapy with CMF [RHR (95% CL) 3.7 (0.8-17.1)] but not in node-negative patients [RHR (95% CL) 1.1 (0.4-2.6)]. In conclusion, our results show that MRP is frequently overexpressed in primary breast cancer and suggest that MRP expression might be of prognostic significance in the subgroups of patients with the more favourable prognosis, i.e. patients with small tumours and node-negative patients, as well as in the setting of adjuvant systemic chemotherapy. In primary breast cancer, MRP might be related to altered cell biological behaviour, including a more aggressive phenotype, and resistance to adjuvant systemic chemotherapy.

ATP-Binding Cassette Transporters↗

Topoisomerase I inhibitors: the relevance of prolonged exposure for present clinical development.

Topoisomerase I inhibitors constitute a new class of anti-cancer agents. Recently, topotecan and irinotecan were registered for clinical use in ovarian cancer and colorectal cancer respectively. Cytotoxicity of topoisomerase I inhibitors is S-phase specific, and in vitro and in vivo studies have suggested that, for efficacy, prolonged exposure might be more important than short-term exposure to high concentration. Clinical development of those topoisomerase I inhibitors that have reached this stage is also focused on schedules aiming to achieve prolonged exposure. In this review, we summarize all published preclinical studies on this topic for topoisomerase I inhibitors in clinical development, namely 20-S-camptothecin, 9-nitro-camptothecin, 9-amino-camptothecin, topotecan, irinotecan and GI147211. In addition, preliminary data on clinical studies concerning this topic are also reviewed. The data suggest that prolonged exposure may indeed be relevant for anti-tumour activity. However, the optimal schedule is yet to be determined. Finally, clinical data are yet too immature to draw definitive conclusions.

Animals↗

Patient perceptions of the side-effects of chemotherapy: the influence of 5HT3 antagonists.

In 1983, Coates conducted a survey that ranked the side-effects perceived by patients receiving chemotherapy in the order of their severity. Vomiting and nausea were found to be the two most distressing side-effects. They have an impact on quality of life and compliance with treatment. The development of 5HT3 antagonists has been a major step forward in the prevention and treatment of chemotherapy-induced nausea and vomiting. Presently, these antiemetics are routinely used as concomitant therapy in emetogenic chemotherapy regimens. The purpose of this study was to evaluate the impact of 5HT3 antagonists on patient perceptions of the side-effects of chemotherapy. Coates' survey was replicated in patients who received 5HT3 antagonists for acute nausea and vomiting resulting from emetogenic chemotherapy. Patients received the survey to identify those physical and non-physical side-effects that they attributed to chemotherapy and were asked to rank the five most distressing side-effects. Of the 197 patients who consented to take part in the study, 181 were evaluable. Nausea, hair loss and vomiting were described as the three most distressing side-effects of chemotherapy. Eighty per cent of all the patients actually experienced nausea and 57% experienced vomiting. Hair loss appeared to be more distressing to women (P < 0.001) but, in other aspects, gender, age and marital status did not influence the ranking of the three most distressing side-effects. Constipation was ranked as 6th and was not identified as a distressing side-effect in 1983. Nausea and vomiting remain to be the first and third most distressing side-effects of chemotherapy, even though the incidence and severity of acute nausea and vomiting are now significantly reduced.

Adolescent↗

Tumour marker concentration at the start of chemotherapy is a stronger predictor of treatment failure than marker half-life: a study in patients with disseminated non-seminomatous testicular cancer.

We investigated the prognostic value of the serum half-life of human chorionic gonadotrophin (HCG) and alpha-fetoprotein (AFP) during induction chemotherapy and the relative prognostic importance of initial marker concentrations and marker half-life. Marker half-lives were calculated using two abnormal values observed between day 8 and day 22 of the first chemotherapy cycle. Moreover, analyses were carried out using day 43 as the second measurement point. Treatment failure at any time was chosen as the end point. The relative prognostic influence of marker half-lives and initial marker concentrations was tested in univariate and multivariate analyses. Half-lives were considered to be prolonged if > 3 days for HCG and > 6 days for AFP. In addition, we separated patients into those with half-lives > 6 days for HCG and those with half-lives > 10 days for AFP to examine whether these long half-lives were associated with a poor prognosis. A group of 669 patients treated with cisplatin combination chemotherapy was studied. Forty-two per cent of the patients had normal HCG and 37% had normal AFP at the start of chemotherapy. At day 22, HCG was still elevated in 138 patients and AFP in 211. At day 43, the numbers of these patients were 35 and 80 respectively. Based on the measurements obtained on day 8 and day 22, a half-life of HCG > 3 days or > 6 days and/or a half-life AFP > 6 days or > 10 days did not accurately predict treatment failure (P=0.413 and P=0.851, respectively; values obtained using tests for trend). However, initial marker concentrations of HCG and/or AFP > 1000 IU l(-1) were highly significant prognosticators for treatment failure (P=0.001 and P < 0.001 respectively), independent of half-life values. Half-lives calculated with the values obtained on day 43 did not contribute to the accuracy of the prediction of treatment failure. We conclude that half-lives of HCG and AFP during induction chemotherapy are inaccurate parameters for the prediction of treatment failure. In contrast, initial serum concentrations of HCG and AFP are highly significant in the prediction of unfavourable treatment outcome.

Analysis of Variance↗

High-dose regimen of interleukin-2 and interferon-alpha in combination with lymphokine-activated killer cells in patients with metastatic renal cell cancer.

Seventy-two patients with metastatic renal cell cancer were treated with the combination of high-dose interleukin-2 (IL2), interferon-alpha (IFN alpha), and lymphokine-activated killer cells (LAK). Seventeen patients were entered in a feasibility part of the study (protocol 1) and 55 in an efficacy part (protocol 2). Protocol 2 differed from protocol 1 in the addition of IFN alpha to the first 5 days of IL2 infusion. Each patient was planned to receive two induction cycles. IL2, 18 MIU/m2/day, was administered continuously i.v. on days 1-5, and IFN alpha, 5 MIU/m2/day (protocol 2), was administered i.m. on days 1-5, followed by three daily lymphaphereses on days 7-9. On day 12, treatment was resumed with IL2 and IFN alpha on days 12-15 and LAK reinfusions on days 12-14. In protocol 1, three complete (CR) and one partial (PR) responses were achieved (response rate 24%). The median duration of response and the median survival were 18.1 and 13.9 months, respectively. The 3-year survival was 35%. Of the 51 evaluable patients in protocol 2, 6 achieved a CR and 13 a PR (response rate 37%). The median duration of response was 11.1 months. The median survival was 16.9 months. The 3-year survival was 35%. There were three treatment-related deaths. Other severe toxicities included hypotension, cardiotoxicity, pulmonary edema, renal toxicity, and infectious complications. In the two induction cycles, only 54 and 42% of the planned doses could be administered. We conclude that the use of high-dose regimens of IL2 and IFN alpha is not warranted, unless we can define more accurately which patients may experience long-term survival as a result of treatment.

Adoptive Transfer↗

Phase I and pharmacologic study of docetaxel and cisplatin in patients with advanced solid tumors.

PURPOSE: This phase I study was performed to assess the feasibility of the combination of docetaxel and cisplatin and to determine the maximum-tolerated dose (MTD) and the side effects with an emphasis on sequence-dependent side effects. MATERIALS AND METHODS: Patients who were not pretreated with taxanes or cisplatin derivatives and who had received no more than one prior combination chemotherapy regimen or two single-agent regimens were entered. Treatment consisted of docetaxel given as a 1-hour infusion followed by cisplatin as a 3-hour infusion (schedule A), or cisplatin followed by docetaxel (schedule B). Docetaxel doses ranged from 55 to 100 mg/m2 and cisplatin doses from 50 to 100 mg/m2. RESULTS: Leukocytopenia and granulocytopenia were common (overall, 90%; grade 3 or 4, 87%), short-lasting, and docetaxel dose-dependent. Infections and neutropenic fever occurred in 10% and 4.5% of courses, respectively. Nonhematologic toxicities were mild to moderate and included alopecia, nausea, vomiting, diarrhea, mucositis, neurotoxicity, fluid retention, and skin and nail toxicity. There were no significant differences in pharmacokinetic parameters between schedules A and B. Tumor responses included one complete response (CR) and nine partial responses (PRs). CONCLUSION: The dose levels docetaxel 100 mg/m2 plus cisplatin 75 mg/m2 and docetaxel 85 mg/m2 plus cisplatin 100 mg/m2 appeared to be manageable. At these dose levels, the median relative dose-intensity was high and 81% and 88% of all cycles, respectively, could be given at full dose. Schedule A is advocated for further treatment.

Adult↗

Importance of bleomycin in combination chemotherapy for good-prognosis testicular nonseminoma: a randomized study of the European Organization for Research and Treatment of Cancer Genitourinary Tract Cancer Cooperative Group.

PURPOSE: This prospective randomized trial was designed to compare the efficacy of etoposide plus cisplatin (EP) versus bleomycin, etoposide, and cisplatin (BEP) chemotherapy in patients with good-prognosis metastatic nonseminomatous testicular cancer. PATIENTS AND METHODS: Four hundred nineteen patients with good-prognosis nonseminomatous testicular cancer were randomized to receive four cycles of cisplatin 20 mg/m2 on days 1 to 5 plus etoposide 120 mg/m2 on days 1, 3, and 5 with or without bleomycin 30 mg weekly. RESULTS: Of 395 eligible patients, 169 of 195 patients allocated to EP (87%) and 189 of 200 patients allocated to BEP (95%) achieved a complete response with chemotherapy alone or after postchemotherapy surgery. These results are significantly different (P = .0075). After a median follow-up duration of 7.3 years, eight patients (4%) on each treatment arm relapsed. In view of the low number of unfavorable treatment outcomes (11%), no significant differences were detected in time to progression (P = .136) and survival (P = .262). Both the acute and late pulmonary toxicity and neurotoxicity were significantly greater in patients who received BEP, whereas Raynaud's phenomenon occurred exclusively in patients who received BEP (P < .001). Two patients treated with BEP died of bleomycin pulmonary toxicity. CONCLUSION: BEP is the most effective combination regimen in the treatment of disseminated nonseminomatous germ cell cancer. In this particular BEP regimen with etoposide at a dose of 360 mg/m2 per cycle, even in good-prognosis patients, bleomycin cannot be deleted without compromising treatment efficacy, but its use is associated with more toxicity (particularly pulmonary) and efforts to reduce this merit further exploration.

Adolescent↗