More than 50% of patients can be cured of AML in childhood. Either drug intensity or each of the induction and postremission phases may have contributed to the outstanding improvement in outcome. Low-dose MT is not recommended. Exposure to this low-dose MT may contribute to clinical drug resistance and treatment failure in patients who experience relapse.

Chronic lymphocytic leukemia cell (CLL) usually (95%) express B-phenotype and the CD5 antigen which is usually present on the surface of normal T cells. However, among B CLL, 7 to 20% do not express CD5. The significance of the lack of CD5 expression remains unclear. We reviewed 42 consecutive CD5- B CLL seen in three French medical centers from 1985 to 1991 and compared them with 79 CD5+ B CLL. Immunophenotype studies were performed using indirect immunofluorescence under light microscopy as well as flow cytometry after 1988. B CLL was considered to be CD5 negative when less than 5% of mononuclear cells expressed CD5 after subtraction of the number of T-cells. Cases with CD5- B CLL had isolated splenomegaly more frequently (p = 2.10(-7)). They frequently expressed a higher level of surface immunoglobulin (S-Ig) or the switch mu/delta phenotype (p = 4.7 10(-2)). The median survival time was not reached but no significant difference between CD5 negative and positive B CLL was observed at the time of our data analysis (p = 0.97). Clinical presentation of CD5- B CLL seems to be different from other forms of B CLL. Although, no conclusion can be reached in terms of prognosis, CLL with low expression of CD5 should be regarded as a subtype of CLL with a different clinical presentation than CD5+ CLL.

High-dose methotrexate (HD-MTX) with leucovorin rescue is a component of therapy in children with acute lymphoblastic leukaemia. Since MTX toxicity is related to drug exposure, a monitoring of serum MTX concentrations at H24, H48, H72 and until the concentration is less than 0.2 micromol/L is commonly performed. However, a number of patients may reach concentrations of less than 0.2 micromol/L long before the next sampling is scheduled. The aim of our study was to develop a Bayesian method predicting the time at which MTX concentration reaches 0.2 micromol/L in order to decrease the number of samples drawn and to allow for a more rapid patient discharge. Methotrexate population parameters were estimated from a retrospective analysis of 60 infusions in 23 children and MTX concentrations were predicted from an independent set of 20 courses in 14 children with a Bayesian approach using either one (H48) or two (H24 and H48) samples. The following population parameters were obtained using a two-compartment model: CL = 3.51 L/h (inter-individual variability: 66%), Vd = 8.67 L (58%), k12 = 0.0044 h(-1)(105%), k21 = 0.039 h(-1)(25%). Clearance and Vd were found to increase with weight and age respectively. Both sampling schedules tested for the Bayesian estimation enabled accurate prediction of concentrations and provided satisfactory precision despite a small bias. When considering the ability to predict the time at which the threshold was reached, the one-sample (H48) schedule gave the best results. We conclude that a sampling schedule involving only one sample and Bayesian parameter estimation may be able to predict the delay necessary to reach 0.2 micromol/L in each individual.

In the LAME89/91 protocol, children with acute myeloid leukemia (AML) who achieved complete remission (CR) after induction chemotherapy, were treated either with allogeneic bone marrow transplantation (BMT) if they had an HLA-compatible related donor or with chemotherapy including high-dose cytarabine. The objectives of this study were to describe the overall results of this strategy and to compare the two post-remission arms. Two hundred and thirty-one children were enrolled in the protocol. Induction chemotherapy consisted of a combination of cytarabine and mitoxantrone. A CR was achieved in 204 children (88%).