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Biomedical subjects

E Gamelin

Publications and source records attributed to E Gamelin.

At least 37 records · Page 2Linked to original sources
PubMed2001

A possible explanation for a neurotoxic effect of the anticancer agent oxaliplatin on neuronal voltage-gated sodium channels.

Oxaliplatin, a new widely used anticancer drug, displays frequent, sometimes severe, acute sensory neurotoxicity accompanied by neuromuscular signs that look like the symptoms observed in tetany and myotonia. The whole cell patch-clamp technique was employed to investigate the oxaliplatin effects on the electrophysiological properties of short-term cultured dorsal unpaired median (DUM) neurons isolated from the CNS of the cockroach Periplaneta americana. Within the clinical concentration range, oxaliplatin (40-500 microM), applied intracellularly, decreased the amplitude of the voltage-gated sodium current resulting in a reduction of half the amplitude of the action potential. For comparison, two other platinum derivatives, cisplatin and carboplatin, were found to be ineffective at reducing the sodium current amplitude. In addition, we compared the oxaliplatin action to those of its metabolites dichloro-diaminocyclohexane platinum (dach-Cl(2)-platin) and oxalate. Oxalate (500 microM) was found to be effective, like oxaliplatin, at reducing the inward sodium current amplitude, whereas dach-Cl(2)-platin (500 microM) failed to change the current amplitude. Interestingly, the effect of oxalate or oxaliplatin could be mimicked by using intracellularly applied 10 mM bis-(o-aminophenoxy)-N,N,N',N'-tetraacetic acid (BAPTA), known as chelator of calcium ions. We concluded that oxaliplatin was capable of altering the voltage-gated sodium channels through a pathway involving calcium ions probably immobilized by its metabolite oxalate. The medical interest of preventing acute neurotoxic side effects of oxaliplatin by infusing Ca(2+) and Mg(2+) is discussed.

Animals↗
PubMed2001

[Cancers of unknown origin: 311 cases].

Carcinoma of unknown primary site has been defined as a metastatic disease without known primary site (upon clinical, radiological or endoscopic examination) at the initial therapeutic decision. The incidence of such carcinomas is between 1.6 and 15% of all adult's tumors. The goals of this retrospective and monocentric study were 1) the incidence of these carcinoma; 2) the utility to identify the primary site; 3) the efficacy of treatment in terms of survival; and 4) the prognostic factors to optimize strategic choices. Between January 1980 to December 1995, 311 cases were identified; this represents 1.6% of all cases treated in our center. Histological analyses of metastases revealed adenocarcinoma: 164 cases (92 males, 72 females; 29 well differentiated, 11 poorly differentiated and 41 undifferentiated); squamous cell carcinoma: 90 cases (78 males, 12 females); undifferentiated carcinoma: 27 cases (21 males, 6 females); neuro-endocrine tumor: 10 cases; and others: 20 cases. Median age was 61.1 years (30-94). Half of the patients had a PS between 0 and 1. The carcinoma was revealed by only one site of metastases in 35% of the cases (lymph node 72.9%, bone 35.5%, liver 19.4% and lung 16.5%). The primary carcinoma was found in only 6% of the cases. Median survival of all patients was only 9 months. Multivariate analyses by the Cox method show four positive prognostic factors: sex (female), performance status (PS < 2), histological analyses (squamous cell carcinoma), only one site of metastases.

Adenocarcinoma↗
PubMed2001

[Pharmacokinetic properties of platinium derivatives].

The three platinum derivatives currently available share many pharmacokinetic and pharmacodynamic (PK-PD) properties but present also some distinct characteristics, due to their structural differences. They result in different systemic PK-PD and metabolic behaviour and toxicity profile. Oxaliplatin is quickly transformed into dach-platinum, the active metabolite, by loosing oxalate chain. Eighty to eighty-eight per cent of platinum are bound to proteins, as for cisplatin, whereas carboplatin is less reactive. Cisplatin and oxaliplatin active metabolites, i.e. monoaquo platin and dach-platin quickly react with small proteins with sulfhydryl groups, such as glutathione, cysteine and methionine, and then with high molecular weight proteins, such as albumin and gammaglobulins through covalent link. Thus, their terminal half lives are long, about ten days, but no platinum accumulation has been reported in plasma with oxaliplatin, whereas after cisplatin administration, both total and ultrafiltrable platinum progressively accumulate in plasma. This difference may play a role in the lack of oxaliplatin nephrotoxicity and its more delayed and reversible neurotoxicity. On the other hand, carboplatin is more stable, less bound to proteins and is largely excreted inchanged in urine. This can explain that it passes more easily through the blood brain barrier. Erythrocytes represent an important deep compartment, especially for oxaliplatin, a little bit less for cisplatin. Oxaliplatin is trapped in erythrocytes through a covalent binding to globin. There, its half life is identical to that of erythrocytes. According to certain authors, this trapping would be involved in the incidence of anemia. On the contrary, carboplatin is quickly extruded from erythrocytes. The three derivatives kinetics in plasma present a wide interindividual variability, resulting in differences in term of toxicity and efficacy. For the three of them, plasma clearance is correlated to creatinine clearance, but only carboplatin dosage can be individually adjusted, based on creatinine clearance measurement, thanks to its simple renal excretion, due to exclusive glomerular filtration, and after Calvert's, Egorin's and Chatelut's population kinetics studies. Cisplatin renal excretion is more complex, combining reabsorption and secretion processes. Therefore, individual dosage adjustment needs platinum concentration measurement in plasma, but there is no general agreement on the platinum species to measure, ultrafiltrable or bound. Oxaliplatin is too recent in clinical practice and still lacks of PK-PD data. These characteristics can help us for a better knowledge of the three platinum derivatives clinical properties, both in term of kinetics, behaviour and toxicity.

Antineoplastic Agents↗
PubMed2000

Docetaxel in combination with 5-fluorouracil in patients with metastatic breast cancer previously treated with anthracycline-based chemotherapy: a phase I, dose-finding study.

This phase I study evaluated the maximum tolerated dose, dose-limiting toxicity and recommended dose of docetaxel in combination with 5-fluorouracil (5-FU) in patients with metastatic breast cancer previously treated with anthracycline-based chemotherapy. 32 patients received docetaxel at 60, 75, 85 or 100 mg/m(2) by 1-h intravenous (i.v.) infusion, followed, after a 1-h interval, by 5-FU at 250, 350, 500 or 750 mg/m(2)/day by continuous infusion over 5 days every 3 weeks. Dose-limiting stomatitis defined the maximum tolerated dose at a docetaxel dose of 100 mg/m(2) with 5-FU 750 mg/m(2)/day. None of 5 patients treated at the previous dose level (docetaxel 85 mg/m(2) with 5-FU 750 mg/m(2)/day) had a dose-limiting toxicity in the first cycle, and this was, therefore, considered the recommended dose. The combination was generally well tolerated. Grade 4 neutropenia was common (29 patients; 91%), but no patient experienced febrile neutropenia of duration >3 days requiring i.v. antibiotics. An objective response was achieved by 18 patients overall (56%), and in 4 out of 5 patients treated with the determined recommended dose. No pharmacokinetic interaction between docetaxel and 5-fluorouracil was apparent. The activity of docetaxel 85 mg/m(2) with 5-fluorouracil 750 mg/m(2)/day will be explored more extensively in phase II studies of patients with metastatic breast cancer previously treated with anthracycline-based chemotherapy.

Adult↗
PubMed2000

Factors predicting for efficacy of oxaliplatin in combination with 5-fluorouracil (5-FU)+/-folinic acid (FA) in a compassionate-use cohort of 370 5-FU-resistant advanced colorectal cancer (CRC) patients.

Univariate and multivariate analyses were performed on data from 370 5-fluorouracil (5-FU)-resistant advanced colorectal cancer patients treated with oxaliplatin (Eloxatin)/5-FU+/-folinic acid (FA) to identify prognostic factors for oxaliplatin-based treatment. The response rate was 14.6% (95% confidence interval (CI): 11.0-18.2%), median time to progression was 4.3 months (95% CI: 3.9-4.7), and median overall survival 9.7 months (95% CI: 8.5-10.8). Multivariate analysis indicated < 2 prior chemotherapy regimens, bi-weekly treatment administration schedule (versus tri-weekly) and continuous chronomodulated delivery (CCM) as significantly associated (P < 0.05) with a higher overall response rate. Performance status (PS) < 2, having only one involved organ, biweekly schedule and CCM were associated (P < 0.05) with a longer time to progression. Good PS, one involved organ, low alkaline phosphatase (AP) serum levels, bi-weekly schedule and CCM were significantly correlated with longer overall survival, while confirming the efficacy of oxaliplatin/5-FU+/-FA in this indication.

Adult↗
PubMed2000

Dose and time dependencies of 5-fluorouracil pharmacokinetics.

OBJECTIVES: The purpose of this study was to examine the interpatient and intrapatient variability of the Michaelis-Menten plasma parameters of 5-fluorouracil administered according to a schedule combining a bolus of 400 mg/m2 followed by 22-hour infusion of 600 mg/m2 for 2 consecutive days. PATIENTS: A pharmacokinetic population approach was used to analyze the data from 21 patients with colorectal cancer. RESULTS: The 5-fluorouracil plasma concentrations versus time were best described by a two-compartment model with nonlinear elimination from the central compartment. The relationships between the pharmacokinetic parameters and patient characteristics were tested. On day 1 the mean values (with interindividual variability as expressed by the coefficient of variation) were 1390 mg x h(-1) (20%), and 5.57 mg x L(-1) (22%) for the maximum rate of elimination, and the half-saturating plasma concentration. The maximum rate of elimination was positively correlated to the body surface area and the percentage of liver involvement by metastatic disease determined by tomodensitometric examination. The model was successfully tested with independent data sets corresponding to other schedules. The analysis of this intrapatient variability showed that the half-saturating plasma concentration increased from day 1 to day 2, especially in the patients with low lymphocyte cell dihydropyrimidine dehydrogenase activity. CONCLUSION: The pharmacokinetic parameters obtained in this study would be useful to predict the 5-fluorouracil plasma concentrations following other schedules of administration of 5-fluorouracil and to study the possible pharmacokinetic interactions between 5-fluorouracil and other drugs.

Adult↗
PubMed2000

Clinical pharmacokinetics of oxaliplatin: a critical review.

Oxaliplatin (cis-[(1R,2R)-1,2-cyclohexanediamine-N,N'] oxalato(2-)-O,O'] platinum; Eloxatine) is a novel platinum coordination complex used for the treatment of metastatic colorectal carcinoma in combination with fluoropyrimidines. The objective of this review is to integrate the key data from multiple studies into a single, comprehensive overview of oxaliplatin disposition in cancer patients. The pharmacokinetics (PKs) of unbound platinum in plasma ultrafiltrate after oxaliplatin administration was triphasic, characterized by a short initial distribution phase and a long terminal elimination phase (t1/2, 252-273 h). No accumulation was observed in plasma ultrafiltrate after 130 mg/m2 every 3 weeks or 85 mg/m2 every 2 weeks. Interpatient and intrapatient variability in platinum exposure (area under the curve(0-48)) is moderate to low (33 and 5% respectively). In the blood, platinum binds irreversibly to plasma proteins (predominantly serum albumin) and erythrocytes. Accumulation of platinum in blood cells is not considered to be clinically significant. Platinum is rapidly cleared from plasma by covalent binding to tissues and renal elimination. Urinary excretion (53.8 +/- 9.1%) was the predominant route of platinum elimination, with fecal excretion accounting for only 2.1 +/- 1.9% of the administered dose 5 days postadministration. Tissue binding and renal elimination contribute equally to the clearance of ultrafilterable platinum from plasma. Renal clearance of platinum significantly correlated with glomerular filtration rate, indicating that glomerular filtration is the principal mechanism of platinum elimination by the kidneys. Clearance of ultrafilterable platinum is lower in patients with moderate renal impairment; however, no marked increase in drug toxicity was reported. The effect of severe renal impairment on platinum clearance and toxicity is currently unknown. Covariates such as age, sex, and hepatic impairment had no significant effect on the clearance of ultrafilterable platinum, and dose adjustment due to these variables is not required. Oxaliplatin undergoes rapid and extensive nonenzymatic biotransformation and is not subjected to CYP450-mediated metabolism. Up to 17 platinum-containing products have been observed in plasma ultrafiltrate samples from patients. These include several proximate cytotoxic species, including the monochloro-, dichloro-, and diaquo-diaminocyclohexane platinum complexes, along with several other noncytotoxic products. Oxaliplatin does not inhibit CYP450 isoenzymes in vitro. Platinum was not displaced from plasma proteins by a variety of concomitant medications tested in vitro, and no marked PK interactions between oxaliplatin, 5-fluorouracil, and irinothecan have been observed. These results indicate that the additive/synergistic antitumor activity observed with these agents is not due to major alterations in drug exposure, and the enhanced efficacy is likely to be mechanistically based. Together, these PK, biotransformation, drug-drug interaction analyses and studies in special patient populations provide a firm scientific basis for the safe and effective use of oxaliplatin in the clinic. These analyses also reveal that the pharmacological activity of oxaliplatin may be attributable, at least in part, to the unique pattern of platinum disposition observed in patients.

Antineoplastic Agents↗
PubMed2000

Early biotransformations of oxaliplatin after its intravenous administration to cancer patients.

This article deals with the fate of oxaliplatin 1 and 3 h after its i.v. administration (130 mg/m(2)) to three patients. Its binding to plasma proteins and penetration into red blood cells were monitored by chromatography on-line with inductively coupled plasma mass spectrometry. Oxaliplatin biotransformations in plasma ultrafiltrate (PUF) and in urine were studied by chromatography coupled to inductively coupled plasma mass spectrometry or to electrospray ionization mass spectrometry. In plasma, four platinum (Pt) compounds were found. The peaks at 200 and 160 kDa corresponding to gamma-globulins contained 40% of the Pt bound; the peak at 60 kDa corresponding to albumin contained 40% of the Pt found. The peak <2 kDa could correspond to oxaliplatin, to its degradation products, or to adducts between Pt compounds and low-molecular-weight species such as glutathione, L-methionine, and L-cysteine. In PUF and urine, oxaliplatin itself, its degradation products, Pt(dach)Cl(2), [Pt(dach)(OH(2))Cl](+), and species that have the same retention times as Pt(dach)(methionine) and [Pt(dach)](2)(glutathione) were found. One hour after infusion, oxaliplatin in PUF and urine represented 12 and 50% of the total Pt, respectively. Three hours after infusion, oxaliplatin, undetectable in PUF, represented 10% of total Pt in urine. Inside red blood cells, two Pt compounds were found. The Pt peak at 60 kDa corresponding to hemoglobin and the peak <2 kDa corresponding to low-molecular species contained, respectively, 60% and 40% of Pt found. This study demonstrates that in the first hours after its infusion, oxaliplatin, in addition to other Pt compounds, is present in plasma and urine and that Pt is bound to albumin, gamma-globulins, and hemoglobin.

Aged↗
PubMed2000

[Pharmacology of platinum analogs-taxanes interactions].

Taxoids and platinum derivatives display a true activity against many types of solid tumors. Their relatively non overlapping toxicity profiles and their different mechanisms of action made their combination attractive. Actually, the frequency and the severity of the toxicity appeared schedule-dependent. Thus, cisplatin-paclitaxel combination generates more neutropenia, when cisplatin is delivered before paclitaxel. Cisplatin reduces paclitaxel plasma clearance, but the interference appears more due to pharmacodynamic interaction. Cisplatin-induced DNA adducts are more limited when paclitaxel is administered before cisplatin. Tolerance is better but we cannot conclude in term of efficacy. Cisplatin and docetaxel interaction and schedule-dependence appear much less obvious in term of toxicity. On the other hand, thrombopenia carboplatin-induced is significatively decreased when combined to paclitaxel. In that case, the interaction is clearly pharmacodynamic. The correlation curve of thrombopenia and platinum in plasma area under the curve is modified and shows an increased tolerance of platelets to carboplatin. The cause remains unknown, to our knowledge. The interaction protects only the platelets. No data is available for docetaxel and carboplatin combination. A better knowledge of the metabolism and the interactions of these two drug families is quite necessary for better using them in combination, both in term of efficacy and tolerance.

Antineoplastic Agents, Phytogenic↗
PubMed1999

Local and sustained delivery of 5-fluorouracil from biodegradable microspheres for the radiosensitization of glioblastoma: a pilot study.

BACKGROUND: The authors have developed a new method of drug delivery into the brain using implantable biodegradable microspheres. In this study, this method was used to provide localized and sustained delivery of 5-fluorouracil (5-FU) after the surgical resection of glioblastoma. This antimetabolite and radiosensitizing drug was selected in an attempt to decrease the rate of local recurrence of the tumor. METHODS: Eight patients with newly diagnosed glioblastoma were included in the study and 2 increasing amounts of 5-FU were studied (70 mg and 132 mg). After surgical resection of the tumor, poly(D-L lactide-co-glycolide) 5-FU-loaded microspheres with an average dimension of 45 microm were implanted in the wall of the surgical bed. External beam radiation (59.4 grays) was initiated before the seventh postsurgical day. Patients were followed by clinical examination, magnetic resonance imaging, and 5-FU assays in the blood and cerebrospinal fluid (CSF). RESULTS: 5-FU assays confirmed sustained concentrations in the CSF for at least 1 month. Concentrations of 5-FU in the blood were lower and transitory. Systemic tolerance to the treatment was good; one case of recurrent brain swelling was observed at the higher dose studied. At the time of last follow-up the overall median survival time was 98 weeks from the time of implantation and 2 patients had achieved disease remission at 139 and 153 weeks, respectively. CONCLUSIONS: This study demonstrates that biodegradable microspheres are efficient systems for drug delivery into the brain and may have future application in the treatment of brain tumors. Further studies are needed to confirm the potential of 5-FU-loaded microspheres for the radiosensitization of glioblastoma. [Please see editorial on pages 197-9, this issue].

Adolescent↗
PubMed1999

Oxaliplatin added to 5-fluorouracil-based therapy (5-FU +/- FA) in the treatment of 5-FU-pretreated patients with advanced colorectal carcinoma (ACRC): results from the European compassionate-use program.

PURPOSE: To provide evidence for the therapeutic efficacy of oxaliplatin (Eloxatin) when given as a 2-6-hour i.v. infusion, alone or in combination with 5-fluorouracil/folinic acid (5-FU +/- FA) in patients with advanced colorectal carcinoma (ACRC) who have failed 5-FU-based therapy. To confirm the safety of the drug and its combination in an extended-access context. PATIENTS AND METHODS: Prescribing physicians were supplied oxaliplatin on a nominative compassionate-use basis, after obtaining informed consent. Europe-wide, 206 ACRC patients in 44 centers received 1168 cycles of chemotherapy with oxaliplatin (80-100 mg/m2 q 2 weeks or 100-135 mg/m2 q 3 weeks) delivered as a short (2-6 hours) i.v. infusion, 177 of them (1026 cycles) receiving oxaliplatin + 5-FU +/- FA. RESULTS: Oxaliplatin added to the 5-FU +/- FA regimens of 111 verified 5-FU-refractory patients (imaging and/or clinical proof of progression under prior 5-FU-based regimen), elicited objective responses in 25 of 98 evaluable patients, (ORR: 25.5%, 95% confidence interval (95% CI: 17-35). The median time to progression was 4.1 months (95% CI: 3.3-5.0) and the median overall survival was 9.6 months (95% CI: 8.2-10.9). Differences in the toxicity profile of the oxaliplatin + 5-FU +/- FA combination appear related to administration modality, dose and schedule of the 5-FU-based regimen. CONCLUSIONS: The addition of oxaliplatin (2-6-hour i.v. infusion) to 5-FU +/- FA regimens is active in ACRC patients with clinical resistance to fluoropyrimidines. The therapeutic index of oxaliplatin + 5-FU +/- FA combinations administered as salvage therapy compares favorably with those reported in recent phase II-III trials involving other new agents or combinations active in 5-FU-refractory ACRC patients.

Adult↗
PubMed1999

Intrinsic drug resistance in primary and metastatic renal cell carcinoma.

Much remains to be learned about drug resistance in the biology of RCC and its metastases. We measured MDR-1/P-glycoprotein expression in 19 tumor samples from patients with metastatic RCC by RNase protection and quantitative PCR assays. The median level of the 16 tumor metastases was 4.9 (range: 0.10 to 156.2) relative to the level of 10 assigned to a reference cell line, SW620, which has been characterized as expressing a minimum level of MDR-1. Since these levels were lower than expected for RCC, we asked whether the metastases possessed a phenotype different from primary RCC and examined MDR-1 expression in 5 paired cell lines derived from primary and metastatic RCC. In 8/10 lines, MDR-1 expression was >10. Relative to the level in the primary line, MDR-1 expression was decreased (3 to 50-fold) in 3 metastatic lines, was increased in 1, and unchanged in 1. MRP mRNA expression was lower in the metastatic lines while EGFR expression was variable. IC50 values for 6 compounds (including 4 standard agents and one new Phase 1 agent) were determined for the paired lines. Rhodamine and calcein efflux assays were performed as measures of P-glycoprotein and MRP function. Rhodamine efflux correlated with MDR-1 mRNA expression (r = 0.87) and with the IC50s (r = 0.60) for paclitaxel in the paired cell lines. In contrast, calcein efflux did not correlate with MRP expression. Lastly, MDR-1 expression correlated with cytokeratin 8 (CK8) protein levels, a measure of cellular differentiation. In sum, these data suggest renal cell carcinoma (RCC) metastases have altered MDR-1 expression potentially due to altered differentiation relative to the primary tumor. Thus, the drug resistance phenotype of primary RCC tumors may not reflect that of their metastases.

ATP-Binding Cassette Transporters↗
PubMed1999

Correlation between uracil and dihydrouracil plasma ratio, fluorouracil (5-FU) pharmacokinetic parameters, and tolerance in patients with advanced colorectal cancer: A potential interest for predicting 5-FU toxicity and determining optimal 5-FU dosage.

PURPOSE: Patients with genetic fluorouracil (5-FU) catabolic deficiencies are at high risk for severe toxicity. To predict 5-FU catabolic deficiencies and toxic side effects, we conducted a prospective study of patients treated for advanced colorectal cancer by high-dose 5-FU. PATIENTS AND METHODS: Eighty-one patients were treated with weekly infusions of 5-FU and folinic acid. The initial 5-FU dose of 1,300 mg/m(2) was individually adjusted according to a dose-adjustment chart. Plasma concentrations of uracil (U) and its dihydrogenated metabolite, dihydrouracil (UH(2)), were measured before treatment, and the ratio of UH(2) to U was calculated. Pharmacokinetic and pharmacodynamic studies were conducted to look for a relationship between the ratio of UH(2) to U and 5-FU metabolic outcome and tolerance. RESULTS: The UH(2)-U ratios were normally distributed (mean value, 2.82; range, 0.35 to 7.13) and were highly correlated to (1) 5-FU plasma levels after the first course of treatment (r =.58), (2) 5-FU plasma clearance (r =.639), and (3) individual optimal therapeutic 5-FU dose (r =.65). Toxic side effects were observed only in patients with initial UH(2)-U ratios of less than 1.8. No adverse effects were noted in patients with UH(2)-U ratios of greater than 2.25. CONCLUSION: The UH(2)-U ratio, easily determined before treatment, could help to identify patients with metabolic deficiency and, therefore, a risk of toxicity.

Adult↗
PubMed1999

[Ovarian serous tumors of limited malignancy and invasive peritoneal implants. Review of the literature].

The prognosis for patients with ovarian serous borderline tumors is generally considered to be excellent. It is worse for women with an advanced stage, especially when invasive peritoneal implants are present. There is no general agreement regarding standard treatment in such cases. To clarify the significance of this invasive peritoneal proliferation and to devise a rational treatment approach, we review the available series. From this review of literature, it appears necessary to emphasize the importance of an initial adequate peritoneal staging of all ovarian tumors. After a complete removal of the lesions, the question of adjuvant therapy must be discussed.

Cystadenoma, Serous↗