RESUMO
CONTEXT: The recombinant human erythropoietin (rHuEPO) stimulates the erythropoiesis process. Because this glycoprotein has a short half-life, it needs to be administrated two to three times a week. One of the technics to solve this issue is the PEGgilation. AIMS: To evaluate the pharmacokinetics (PK) and pharmacodynamics of two new branched PEGylated erythropoietins (i.e., an asymmetric 32 kDa-PEG2-rHuEPO and a symmetric 40 kDa-PEG2-rHuEPO molecule) compared to non-PEGylated ior®EPOCIM and MIRCERA®. METHODS: Serum concentrations of both PEGylated and non-PEGylated erythropoietins were measured at various time points in order to determine PK parameters using non-compartmental analysis approach. The reticulocyte (%), erythrocyte count and hemoglobin levels were ascertained in order to compare the effect of these molecules after administrating a single intravenous dose (10 µg/kg) of each product in male New Zealand rabbits. RESULTS: Both branched PEGylated erythropoietin forms exhibited half-lives that were significantly longer than ior®EPOCIM (p<0.05), but not statistically different to MIRCERA®. The mean elimination half-life increased from 4 h (ior®EPOCIM) to 131 h for the 32 kDa-PEG2-rHuEPO and 119 h for the 40 kDa-PEG2-rHuEPO. Conversely, MIRCERA® exhibits a half-life of 64 h. Both PEGylated erythropoietin products significantly enhanced the stimulating effect on reticulocytes and erythrocytes formation, as well as on hemoglobin levels, when compared to ior®EPOCIM treatment up to 42 days post-dose. CONCLUSIONS: The PEGylation strategy employed in this study is an effective method to modify the pharmacokinetics and pharmacodynamics of rHuEPO molecule achieving higher half-lives and, therefore, longer in vivo bioactivity. Both of the branched PEGylated-EPO forms tested are promising candidates for human testing.
CONTEXTO: La eritropoyetina humana recombinante (rHuEPO) estimula la formación de eritrocitos en la medula ósea. Esta glicoproteína terapéutica presenta rápida eliminación en el organismo. Una de las estrategias tecnológicas para resolver esta problemática es la PEGgilación. OBJETIVOS: Evaluar la farmacocinética y la farmacodinámica de dos nuevas eritropoyetinas PEGiladas ramificadas (una asimétrica de 32 kDa-PEG2-rHuEPO y otra simétrica de 40 kDa-PEG2-rHuEPO) en comparación con ior®EPOCIM y el producto de referencia MIRCERA®. MÉTODOS: Se midieron las concentraciones séricas de eritropoyetina PEGilada y no PEGilada, a diferentes tiempos, para determinar los parámetros farmacocinéticos usando el método de análisis no compartimental. Se determinaron los % de reticulocitos, los niveles de eritrocitos y hemoglobina para comparar el efecto de estas moléculas después de administrar a dosis única 10 µg/kg por vía intravenosa en conejos Nueva Zelanda machos. RESULTADOS: Las eritropoyetinas PEGiladas ramificadas presentaron semividas significativamente superiores a ior®EPOCIM (p<0.05), pero no fueron estadísticamente diferentes a MIRCERA®. El t1/2 aumentó de 4 h (ior®EPOCIM) a 131 h para la 32 kDa-PEG2-rHuEPO y 119 h para la 40 kDa-PEG2-rHuEPO, respectivamente. Ambas eritropoyetinas PEGiladas mejoraron significativamente el efecto estimulante sobre la formación de reticulocitos y eritrocitos, así como los niveles de hemoglobina, en comparación con ior®EPOCIM hasta 42 días después de la dosis. CONCLUSIONES: La estrategia de PEGilación, empleada en este estudio, es un método efectivo para modificar la farmacocinética y farmacodinamia de moléculas de eritropoyetinas. Esta tecnología permitió aumentar la semivida de estas moléculas, así como prolongar su bioactividad in vivo. Ambas formas ramificadas de rHuEPO PEGiladas son candidatos prometedores para su uso clínico.
RESUMO
Apoptosis seems to play an important role in cancer immunotherapy outcome. We have studied the kinetic pattern of apoptosis induction in H125 human lung carcinoma xenografts after treatment with the monoclonal antibody (MAb) anti-epidermal growth factor receptor (EGFr) IOR EGF/r3. Tumor-bearing nude mice were injected intravenously with a single 8 mg/kg dose of IOR EGF/r3 and tumor specimens were taken up to 30 days post treatment. Apoptosis was measured by morphometric analysis of the histological sections at each tumor specimen over time points. The results showed a significant apoptotic response in tumors within six days after injection of this MAb reaching a peak at 20 days post treatment. The kinetics were very broad, with apoptotic cells present over the entire time-frame. However, the time course of the apoptotic index showed a significant difference to the mitotic index. Finally, the MAb-induced apoptosis was related to tumor growth delay indicating a probable arrest of cell cycle and a corresponding inhibition of tumor progression, which was corroborated by the Ki67 and proliferating cell nuclear antigen (PCNA) biomarkers.
