Prostaglandins and thromboxane are lipid signaling molecules deriving from arachidonic acid by the action of the cyclooxygenase isoenzymes COX-1 and COX-2. The role of cyclooxygenases (particularly COX-2) and prostaglandins (particularly PGE2) in cancer-related inflammation has been extensively investigated. In contrast, COX-1 has received less attention, although its expression increases in several human cancers and a pathogenetic role emerges from experimental models. COX-1 and COX-2 isoforms seem to operate in a coordinate manner in cancer pathophysiology, especially in the tumorigenesis process. However, in some cases, exemplified by the serous ovarian carcinoma, COX-1 plays a pivotal role, suggesting that other histopathological and molecular subtypes of cancer disease could share this feature. Importantly, the analysis of functional implications of COX-1-signaling, as well as of pharmacological action of COX-1-selective inhibitors, should not be restricted to the COX pathway and to the effects of prostaglandins already known for their ability of affecting the tumor phenotype. A knowledge-based choice of the most appropriate tumor cell models, and a major effort in investigating the COX-1 issue in the more general context of arachidonic acid metabolic network by using the systems biology approaches, should be strongly encouraged.

The medium-risk B cell precursor acute lymphoblastic leukemia (ALL) accounts for 50-60% of total childhood ALL and comprises the largest number of relapses still unpredictable with diagnostic criteria. To evaluate the prognostic impact of minimal residual disease (MRD) in this specific group, a case control study was performed in patients classified and treated as medium (or intermediate)-risk according to the criteria of national studies (ALL-BFM 90, DCLSG protocol ALL-8, AIEOP-ALL 91), which includes a good day 7 treatment response. Standardized polymerase chain reaction (PCR) analysis of patient-specific immunoglobulin and T cell receptor gene (TCR) rearrangements were used as targets for semiquantitative estimation of MRD levels: у10 −2 , 10 −3 , р10 −4 . Twenty-nine relapsing ALL patients were matched with the same number of controls by using white blood cell count (WBC), age, sex, and time in first complete remission, as matching factors. MRD was evaluated at time-point 1 (end of protocol Ia of induction treatment, ie 6 weeks from diagnosis) and time-point 2 (before consolidation treatment, ie 3 months from diagnosis). MRD-based high risk patients (у10 −3 at both time-points) were more frequently present in the relapsed cases than in controls (14 vs 2), while MRD-based low risk patients (MRD negative at both time-points) (1 vs 18) showed the opposite distribution. MRD-based high risk cases experienced a significantly higher relapse rate than all other patients, according to the estimated seven-fold increase in the odds of failure, and a much higher rate than MRD-based low risk patients (OR = 35.7; P = 0.003). Using the Cox model, the prediction of the relapse-free interval at 4 years was 44.7%, 76.4% and 97.7% according to the different MRD categories. MRD-based risk group classification demonstrate their clinical relevance within the medium-risk B cell precursor ALL which account for the largest number of unpredictable relapses, despite the current knowledge about clinical and biological characteristics at diagnosis. Therefore, MRD detection during the first 3 months of follow-up can provide the tools to target more intensive therapy to those patients at true risk of relapse. Leukemia (2000) 14, 1939-1943.

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Summary:The factors possibly affecting the collection of peripheral blood stem cells (PBSC) were evaluated in 104 de novo acute leukemia patients (66 myeloid and 38 lymphoblastic leukemias) in first cytological complete remission (CR); all patients achieved CR after first-line induction chemotherapy. The acute myeloid leukemia patients (AML) were given consolidation-mobilization chemotherapy with cytarabine, and daunoblastin or mitoxantrone or idarubicin; the acute lymphoblastic leukemia patients (ALL) were given consolidation-mobilization chemotherapy with cytarabine and etoposide. In all patients, the collection of PBSC was performed during recovery after giving consolidation chemotherapy and granulocyte colony-stimulating factor (G-CSF). Two main groups were considered according to the CD34 þ cells  10 6 /kg b.w. collected, that is, poor mobilizers (PM), with a collection of o2  10 6 /kg and good mobilizers, with a collection of 42  10 6 /kg. Of 104 patients, 27 (25.9%) were PM; 20/27 had AML and 7/27 had ALL. At multivariate analysis, a lower CD34 þ cells count premobilization chemotherapy (CD34 steady state), the presence of FUO (fever of unknown origin) or infection, and a lower number of CD34 þ cells on the first day of collection correlated with poor mobilization. These results may enable early recognition of patients who may have poor mobilization, and aid selection of patients for different mobilization regimens.

Although most relapses of childhood acute lymphoblastic leukemia (ALL) occur 24-36 months after first CR has been achieved, few patients relapse 5 or more years after CR achievement. The assessment of clonality has proved to be useful in determining whether even those very late events represent the reoccurrence of the original clone or alternatively a secondary leukemia. To gain further information on clonal stability in such late relapse, we performed detailed comparative Southern blotting and PCR analyses of TcR␦ and TcR␥ gene rearrangements in five ALL at presentation and subsequent relapse which occurred more than 5 years after diagnosis. At least one stable rearranged allele of the TcR␦ and TcR␥ loci was traced in all cases at presentation and clinical relapse despite a wide heterogeneity of the pattern of rearrangements. Our study extends to a larger series of patients previous findings which have sought to analyze the phenomenon of clonal evolution in children relapsed after more than 5 years of CCR. With respect to the potential pitfalls in monitoring minimal residual disease in childhood ALL for the presence of clonal evolution, our results highlight the combination of two target genes (such as TcR␥ and TcR␦) as a tool to reduce false negative MRD results.