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Évaluer la mise en application des recommandations de prise en charge thérapeutique des neutropénies fébriles au sein du Réseau d’Île-de-France d’hémato-oncologie pédiatrique (RIFHOP) et l’incidence des infections documentées au cours des neutropénies fébriles.

The expression of recombinant proteins with the Semliki Forest Virus (SFV) system has been scaled up to bioreactor scale. As a model protein for this study the human 5-HT3receptor was chosen. The gene for the receptor was subcloned into the SFV expression plasmid pSFV1. Virus production by in vivopackaging and production of the recombinant protein was scaled up, the latter to a reactor volume of 11.5 l. A VibromixTMagitation system was chosen to overcome aggregation problems of BHK cells in suspension. In the process, cells were first grown to a density of 106cells/ml, the medium was then exchanged with fresh medium and the culture was infected with the recombinant virus at an estimated multiplicity of infection of 30. 24 h post infection we measured an expression level of 3 million functional 5-HT3receptors per cell. For harvesting, the cells were pelleted by centrifugation. The receptor protein was purified in a single step (Hovius et al., 1998) by exploiting the hexa-His tag at minimal protein loss (51% yield). Experiments to optimise expression resulted in yields up to 8 million receptors per cell, when the pH of a suspension culture was controlled at pH 7.3. Rapid virus generation and protein production, high protein yields as well as successful large scale application have made the SFV expression system attractive to produce large quantities of recombinant protein in a very short time. After optimisation of the expression conditions (in particular by setting the pH at 7.3), yields were increased twofold.

TLS is a frequent metabolic complication of hematologic malignant diseases which can generate important renal impairment. As described in previous studies (Goldman S.C. et al, Blood2001;97, 2998–3003 and Pui C.H. et al., J.Clin.Oncol.2001;19, 697–704), there are High Risk (HR) patients (pts) of TLS. Rasburicase a recombinant urate oxidase enzyme transforms uric acid into the highly soluble compound allantoin which is then excreted by the kidneys. Rasburicase is highly effective in prevention and treatment of TLS. Based on these studies, the SFCE made the following recommandations for the management of TLS in children. HR pts are defined as : B cell Acute Lymphoblastic Leukemia (ALL), ALL or Acute Myeloblastic Leukemia (AML) with initial leukocyte count of at least 50x109/L, Stage III and IV T or B Non Hodgkin Lymphoma (NHL), any leukemia or NHL with a plasma uric acid concentration of at least 300 mmoles/L if <10 years old or 350 mmoles/L if >10 years old, serum creatinine or lactate deshydrogenase concentration (LDH) exciding twice the upper limit of normal (N), hyperphosphatemia ≥2mmoles/L. These pts are treated by hyperhydratation (3L/m2) ±alkaline and Rasburicase 0,20 mg/kg/d x 5days. Rasburicase is carried on if serum creatinine > 1,5N or phosphatemia >3mmoles/L or plasma uric acid concentration ≥200mmoles/L and until normalization. Low Risk (LR) pts are defined as pts not HR. They are treated by hyperhydratation (3L/m2) and Rasburicase 0,20 mg/kg/d for one day only. Rasburicase is carried on during 4 days or more on the same biological basis as HR pts. In order to check the validity of those guidelines, we are conducting a survey looking at the evolution of the pts managed according to the SFCE recommandations.150 pts are planned for a 6 months study. On July 30th, 39 pts are registred : 25 ALL, 6 AML, 8 NHL (3 Burkitt). At that time there is no SLT complication. Results will be presented at the 2004 ASH Meeting.

TLS is a frequent metabolic complication of hematologic malignant diseases which can generate important renal impairment. As described in previous studies (Goldman S.C. et al, Blood 2001; 97, 2998–3003 and Pui C.H. et al., J.Clin.Oncol. 2001; 19, 697–704), there are High Risk (HR) patients (pts) of TLS. Rasburicase a recombinant urate oxidase enzyme transforms uric acid into the highly soluble compound allantoin which is then excreted by the kidneys. Rasburicase is highly effective in prevention and treatment of TLS. Based on these studies, the SFCE made the following recommandations for the management of TLS in children. HR pts are defined as : B cell Acute Lymphoblastic Leukemia (ALL), ALL or Acute Myeloblastic Leukemia (AML) with initial leukocyte count of at least 50x109/L, Stage III and IV T or B Non Hodgkin Lymphoma (NHL), any leukemia or NHL with a plasma uric acid concentration of at least 300 mmoles/L if <10 years old or 350 mmoles/L if >10 years old, serum creatinine or lactate deshydrogenase concentration (LDH) exciding twice the upper limit of normal (N), hyperphosphatemia ≥2mmoles/L. These pts are treated by hyperhydratation (3L/m2) ±alkaline and Rasburicase 0,20 mg/kg/d x 5days. Rasburicase is carried on if serum creatinine > 1,5N or phosphatemia >3mmoles/L or plasma uric acid concentration ≥200mmoles/L and until normalization. Low Risk (LR) pts are defined as pts not HR. They are treated by hyperhydratation (3L/m2) and Rasburicase 0,20 mg/kg/d for one day only. Rasburicase is carried on during 4 days or more on the same biological basis as HR pts. In order to check the validity of those guidelines, we are conducting a survey looking at the evolution of the pts managed according to the SFCE recommandations.150 pts are planned for a 6 months study. On July 30th, 39 pts are registred : 25 ALL, 6 AML, 8 NHL (3 Burkitt). At that time there is no SLT complication. Results will be presented at the 2004 ASH Meeting.