Le cetuximab (CTX) est un anticorps monoclonal anti-EGFR indiqué dans les cancers ORL dont les modalités de prescription pourraient être améliorées. Après chimiothérapie d’induction (étude Tremplin), en comparaison au cisplatine, il était moins toxique mais sans améliorer la préservation laryngée. À la première injection, le CTX peut déclencher un choc anaphylactique lié à la préexistence d’IgE anti-αGal. Des tests prédictifs détectant ces IgE ont été développés et réalisés chez 41 patients avec une sensibilité et une valeur prédictive négative de 100%. La relation entre concentrations sériques et efficacité/toxicité a été étudiée chez 34 patients. La pharmacocinétique a été décrite à l’aide d’un modèle combinant des mécanismes d’élimination non saturable (CL) et saturable (k0). La clairance globale du CTX, reflet de l’exposition des patients, était reliée aux survies sans progression et globale (SG). Le grade de radiodermite était associé à la SG. Une simulation pharmacocinétique suggère, qu’en comparaison à l’injection standard de CTX, une injection toutes les trois semaines entrainera des AUC proches mais des concentrations résiduelles différentes. / Cetuximab (CTX) is an anti-EGFR monoclonal antibody approved in head and neck cancer, which prescription modalities may be improved. After induction chemotherapy (Tremplin study), compared to cisplatin, CTX was less toxic but did not improve larynx preservation. During first infusion, CTX can induce an anaphylaxis reaction due to the presence of preexisting anti-αGal IgE. Predictive assays detecting these IgE were developed and tested in 41 patients, with sensitivity and negative predictive values of 100%. Relationship between serum concentrations and efficacy/toxicity was studied in 34 patients. CTX pharmacokinetics was described using a model combining non-saturable (CL) and saturable (k0) eliminations. Global clearance, which reflects patient exposure, was related to progression free and overall (OS) survivals. Severe radiation dermatitis was also associated with OS. A pharmacokinetic simulation suggests that, in comparison to standard CTX infusion, an infusion every three weeks will lead to similar AUC but to different residual concentrations.

Les anticorps monoclonaux ont révolutionné le traitement de nombreuses pathologies. Cependant, leur pharmacocinétique (PK) et l’influence de leur concentration sur la réponse clinique restent mal connues. Nous avons étudié les sources de variabilité interindividuelle de la PK du cetuximab, un anticorps anti- EGFR, ainsi que l’influence de l’exposition à cet anticorps sur la réponse. Nous avons validé une méthode ELISA de dosage du cetuximab. Dans un modèle murin, nous avons étudié l’absorption pulmonaire du cetuximab. Nous avons étudié la PK du cetuximab chez un patient hémodialysé. Nous avons décrit la PK du cetuximab chez des patients traités pour cancer colorectal métastatique, à l’aide d’un modèle combinant des éliminations d’ordre 0 et 1. Enfin, nous avons identifié la clairance globale du cetuximab, paramètre pouvant être estimé précocement par la concentration résiduelle à J14, comme un facteur influençant la survie sans progression des patients. Nos travaux montrent qu’une description de la PK d’un anticorps par approche compartimentale permet d’identifier les sources de variabilité et d’étudier l’impact de la PK sur la réponse clinique. / Monoclonal antibodies have profoundly modified the treatment of many diseases. However, their pharmacokinetics (PK) and the influence of their concentrations on the clinical response are poorly known. We studied the sources of the interindividual variability of PK of cetuximab, an anti-EGFR, and the influence of the exposure to this antibody on the response. We validated an ELISA technique to measure cetuximab concentrations. We studied the pulmonary absorption of cetuximab in a murine model. We studied cetuximab PK in a hemodialysed patient. In metastatic colorectal cancer patients, we described cetuximab PK with the help of a model combining zero- and first-order eliminations. Finally, we identified the global clearance of cetuximab, a parameter which can be estimated by residual concentration on day 14, as a factor influencing progression-free survival of the patients. Our work shows that the description of the PK of an antibody by compartmental approach allows to identify sources of variability and to study the impact of PK on the clinical response.

O prognóstico de pacientes portadores de sarcomas de partes moles (SPM) avançados é reservado. Aumentar o benefício de quimioterapia é necessário, sendo, uma das estratégias, quimioterapia em dose densa, a qual demonstrou benefício em câncer de mama. Por outro lado, a busca de um marcador prognóstico é importante para uma melhor seleção de pacientes que se beneficiariam de protocolo de tratamento mais intensivo. A ezrina é uma proteína que liga o citoesqueleto celular a proteínas de membrana, está associada a invasão celular e metástase e sua hiperexpressão tem sido associada a um pior prognóstico em sarcomas de partes moles. O objetivo deste estudo foi avaliar o papel de quimioterapia com dose densa em pacientes portadores de SPM de alto grau, avançados. O desfecho primário foi taxa de resposta e os secundários foram sobrevida global (SG), sobrevida livre de progressão (SLP), perfil de toxicidade, qualidade de vida e controle de dor. Avaliou-se também a expressão de ezrina por imunohistoquímica como marcador de prognóstico, com o intuito de estratificação da população que poderia se beneficiar mais desta abordagem intensificada. Neste estudo de fase II prospectivo, vinte e um pacientes foram incluídos. A idade mediana foi 37 anos (23-60) e extremidades inferiores foram o sítio primário mais comum. Sarcoma sinovial, leiomiossarcoma e sarcoma sem outras especificações foram as histologias mais frequentes. O protocolo consistiu de seis ciclos seqüenciais de doxorubicina 30mg/m2 D1-3 e ifosfamida 2,5g/m2 D1-5 a cada 14 e 21 dias, respectivamente, seguidos por sete dias de suporte hematopoiético. As intensidades de dose medianas de doxorrubicina e ifosfamida foram, respectivamente, 42mg/m2/semana e 3,63g/m2/semana (93% e 87% do planejado, respectivamente) e 15 pacientes (71%) receberam todo o tratamento. Toxicidades graus 3 e 4 foram observadas em 19 pacientes e em 77/105 ciclos, neutropenia febril em 6 ciclos (5 pacientes) e reduções da fração de ejeção de ventrículo esquerdo de pelo menos 10% em três pacientes. Não houve toxicidade renal provavelmente pela adminsitração da ifosfamida em duas horas. A resposta foi avaliada pelos critérios de RECIST, com três respostas parciais, totalizando uma taxa de resposta de 14%. Seis respostas deveriam ser observadas para que o estudo completasse a inclusão de todos os pacientes programados. Como não se atingiu a taxa de resposta prevista, o protocolo foi fechado. Três mortes precoces foram observadas com suspeita de toxicidade. Após seguimento mediano de 11 meses, a SLP e a SG medianas foram 8,1 e 20,1 meses respectivamente. Pacientes com sarcoma sinovial e idade inferior a 45 anos apresentaram maior sobrevida na análise univariada. A expresão de ezrina foi positiva em 10 pacientes (47%) e houve tendência a uma correlação direta entre sua expressão e sobrevida mais longa (p=0,1191). Todos os pacientes com histologia sinovial foram positivos para ezrina (teste de Fischer, p= 0,0325). Este esquema de quimioterapia sequencial com dose densa de doxorubicina e ifosfamida foi tóxico, a taxa de resposta foi baixa em um grupo de pacientes com doença avançada e não pode ser empregado na prática clínica diária fora de protocolo de pesquisa / Advanced soft tissue sarcoma (STS) patients have a dismal prognosis. Efforts to increase benefit from chemotherapy are needed and dose-dense chemotherapy could be an option, since this approach has demonstrated survival benefit in breast cancer. On the other hand, the identification of a prognostic marker is essential to stratify which patients could benefit most from intensified strategies. Ezrin is a member of the ERM (ezrin, radixin, moesin) cytoeskeleton-associated protein family associated with invasion and metastasis, and has been pointed as important prognostic marker in sarcomas. The objective of this study was to explore the role of dose-dense doxorubicin- and ifosfamide-based chemotherapy in advanced high grade STS patients. Primary endpoint was response rate and secondary endpoints were overall survival (OS), progression free survival (PFS), toxicity profile, quality of life and pain control evaluation. Tumor ezrin immunoreactivity was an exploratory endpoint as a predictor of response to chemotherapy and as a prognostic factor in this population, trying to find which patients could benefit most from this intensified strategy. This prospective, single arm, phase II study included 21 advanced STS patients. Median age was 37 years (23-60y) and lower limbs were the most frequent primary site. Synovial, leiomyo and unclassified sarcoma were the most common histologies. Protocol consisted of 6 cycles of sequential dose-dense doxorubicin 30 mg/m2 D1-3 and ifosfamide 2.5 g/m2 D1-5 every 14 and 21 days, respectively, followed by seven days of hematopoietic support. The median doxorubicin and ifosfamide dose-intensities were, respectively, 42 mg/m2/week and 3.63 g/m2/week (93% and 87% of planned, respectively) and 15 patients (71%) received all cycles. Grade 3/4 toxicities occurred in 19 patients and 77/105 cycles, febrile neutropenia in 5 patients (six cycles) and three LVEF drops of at least 10%, one symptomatic. No renal toxicity was observed what could occurred due to the two-hour-schedule of ifosfamide. Responses were evaluated by RECIST criteria and three patients presented partial response (response rate of 14%). Six responses were necessary to the inclusion of the target population, however, this was not observed and the study was closed. Three deaths were probably related to toxicity. After a median follow-up was 11 months, PFS and OS were 8.1 months and 20.1 months, respectively. Patients with synovial sarcoma and those younger than 45y presented better survival at univariate analysis. Ezrin expression was positive in 10 patients (47%) and a trend was observed for a correlation between positive ezrin expression and longer survival (p= 0.1191). There was a statistically significant correlation between positive ezrin expression and synovial hystology (Fishers exact test, p= 0.0325). This sequential dosedense doxorubicin/ifosfamide-based chemotherapy protocol was toxic, response rate was low in advanced STS patients and can not be considered for routine practice outside clinical trials

No description available.

The teratogenic potential of commercial formulations of atrazine (40.8%) and 2,4-D was evaluated using FETAX (frog embryo teratogenic assay--Xenopus). Because these herbicides have been detected in ground and surface water, this study was designed to determine the adverse effects in buffer and natural water for both herbicides. All treatments showed a significant concentration-response effect on exposed embryos, except for the 2,4-D natural water sample. Atrazine (solubility of the commercial formula used 70 mg/L at 20 degrees C), compared to 2,4-D (solubility = 311 mg/L at pH = 1 and 25 degrees C), had a significantly greater teratogenic effect in both the buffer (atrazine EC50 = 33 mg/L, LC50 = 100 mg/L, TI = 3.03; 2,4-D EC50 = 245 mg/L, LC50 = 254 mg/L, TI = 1.04) and natural water samples (atrazine EC50 < 8 mg/L, LC50 = 126 mg/L; 2,4-D EC50 and LC50 > 270 mg/L). The 2,4-D EC50 and LC50 values for the buffer were similar at 245 mg/L and 254 mg/L. These similar values and the teratogenic index (TI) of 1.04 suggested that 2,4-D was more embryotoxic than teratogenic to frog embryos at high concentrations. Atrazine in natural water demonstrated a significantly greater EC50 (100% abnormality at 8 mg/L, the lowest test concentration) to frog embryos than the buffer experiment (EC50 = 33 mg/L). The extrapolated lowest observable adverse effect concentration (LOAEC) for the natural water experiment was 1.1 mg/L. These results suggest that atrazine toxicity is enhanced by the synergistic or additive effects of some component of the water or atrazine was already present in the sample. In contrast to atrazine, 2,4-D was less toxic in natural water than buffer. These results suggest that both atrazine and 2,4-D pose little threat, since their embryotoxicity and teratogenicity to frog embryos occur at high concentrations approaching their maximum solubility levels in water.

Thesis (M.S.)--Uniformed Services University of the Health Sciences, 2005. / Typescript (photocopy).

Thesis (M.S.)--Uniformed Services University of the Health Sciences, 2005. / Typescript (photocopy).

Thesis (Ph. D.)--Uniformed Services University of the Health Sciences, 2005. / Typescript (photocopy).

Alcoholic beverages have been classified as carcinogenic to humans. As alcoholic beverages are multicomponent mixtures containing several carcinogenic compounds, a quantitative approach is necessary to compare the risks. Fifteen known and suspected human carcinogens (acetaldehyde, acrylamide, aflatoxins, arsenic, benzene, cadmium, ethanol, ethyl carbamate, formaldehyde, furan, lead, 4-methylimidazole, N-nitrosodimethylamine, ochratoxin A and safrole) occurring in alcoholic beverages were identified based on monograph reviews by the International Agency for Research on Cancer. The margin of exposure (MOE) approach was used for comparative risk assessment. MOE compares a toxicological threshold with the exposure. MOEs above 10,000 are judged as low priority for risk management action. MOEs were calculated for different drinking scenarios (low risk and heavy drinking) and different levels of contamination for four beverage groups (beer, wine, spirits and unrecorded alcohol). The lowest MOEs were found for ethanol (3.1 for low risk and 0.8 for heavy drinking). Inorganic lead and arsenic have average MOEs between 10 and 300, followed by acetaldehyde, cadmium and ethyl carbamate between 1,000 and 10,000. All other compounds had average MOEs above 10,000 independent of beverage type. Ethanol was identified as the most important carcinogen in alcoholic beverages, with clear dose response. Some other compounds (lead, arsenic, ethyl carbamate, acetaldehyde) may pose risks below thresholds normally tolerated for food contaminants, but from a cost-effectiveness point of view, the focus should be on reducing alcohol consumption in general rather than on mitigative measures for some contaminants that contribute only to a limited extent (if at all) to the total health risk.

OBJECTIVE: Complaints of cognitive changes are often expressed by patients at all stages of HIV infection. Such changes include decreased memory and attention span, diminished concentration, apathy, and "slowing." Methylphenidate (MPD) has been used in several clinical studies in men with late-stage HIV disease in an attempt to ameliorate these difficulties. The objectives of this review article are to review salient psychopharmacological characteristics of MPD and to describe the research and clinical literature supporting the use of MPD in patients at all stages of HIV infection. METHODS: Seven studies, case reports, or abstracts from International Conferences on AIDS were available in the English literature through August, 1993, directly addressing the use of MPD in patients with HIV disease. Twenty-nine papers were reviewed for pharmacokinetic data, eighteen for safety and side effects issues, and seventeen for relevant contributions from the neuropsychological testing literature. RESULTS: Studies in clinical settings have used doses ranges from 10-90 mg. per day in two or three divided doses with reportedly good results in improving both affective and cognitive symptoms associated with HIV disease. Side effects have been relatively mild and patient satisfaction with treatment has been high. However, no studies have been conducted in early stage HIV disease, where a significant minority of patients have similar complaints in the absence of clinically apparent immunosuppression. Likewise, placebo-controlled, dose-finding studies in AIDS patients are entirely lacking, and no studies in women with HIV disease and cognitive changes have been published. CONCLUSIONS: In spite of these important research short-comings, clinical experience with MPD treatment of cognitive changes in men with HIV/AIDS is consistent with the notion that this medication holds significant promise to improve the quality of life for persons living with HIV/AIDS. Controlled studies to test this hypothesis are warranted.