This manuscript describes the experience from registration until randomisation for a cohort of 2260 patients with osteosarcoma who joined the EURAMOS-1 trial. This includes pre-operative chemotherapy and surgery. It sets out the practical issues in collaboration and in achieving randomisation.

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Vertebrates express two A-type cyclins; both associate with and activate the CDK2 protein kinase. Cyclin A1 is required in the male germ line, but its molecular functions are incompletely understood. We observed specific induction of cyclin A1 expression and promoter activity after UV and ␥-irradiation which was mediated by p53. cyclin A1 ؊/؊ cells showed increased radiosensitivity. To unravel a potential role of cyclin A1 in DNA repair, we performed a yeast triple hybrid screen and identified the Ku70 DNA repair protein as a binding partner and substrate of the cyclin A1-CDK2 complex. DNA double-strand break (DSB) repair was deficient in cyclin A1؊/؊ cells. Further experiments indicated that A-type cyclins activate DNA DSB repair by mechanisms that depend on CDK2 activity and Ku proteins. Both cyclin A1 and cyclin A2 enhanced DSB repair by homologous recombination, but only cyclin A1 significantly activated nonhomologous end joining. DNA DSB repair was specific for A-type cyclins because cyclin E was ineffective. These findings establish a novel function for cyclin A1 and CDK2 in DNA DSB repair following radiation damage.The cell cycle is regulated by external signals, especially in multicellular organisms, where cell proliferation is central to growth and differentiation (34). Internal signals ensure that cell cycle transitions do not occur until all required molecular events have been completed (20). The internal signals become evident as cell cycle checkpoints upon an insult to the cell (e.g., DNA damage) which arrests the cell cycle while repair occurs (10,14). Both internal and external signals modulate the activity of the cyclin-dependent kinases (CDKs) that catalyze the ordered transitions from one phase of the cell cycle to the next. Cyclin E and cyclin A2 both associate with CDK2, and cyclin A2 is essential for DNA replication and proliferation in somatic cells (8). Embryos with a homozygous deletion of cyclin A2 are not capable of proliferative growth (28). During G 1 and S phases, the kinase activity of CDK2 associates first with cyclin E and later with cyclin A2. The timing of these processes as well as the appropriate concentration of cyclin/CDK2 complexes is crucial for successful DNA replication (8).Cyclin A1 is a second A-type cyclin that binds CDK2. Cyclin A1 is abundantly expressed in the testis and has previously been shown to be essential for entry into the metaphase of meiosis I in the male germ line in mice (38, 44). Cyclin A1 is expressed at low levels in most other tissues, but no phenotype other than male infertility has been reported for mice lacking the cyclin A1 gene (19,42). The expression of cyclin A1 in hematopoietic progenitor cells and in acute myeloid leukemia is best characterized in somatic cells (46). Surprisingly, recent microarray data suggested that cyclin A1 was transcriptionally induced following p53 activation (21).Thus, the physiological role of cyclin A1 in somatic cells remains unknown. This prompted us to analyze the mechanisms of cyclin A1 induction in somatic cel...

Relapse of Ewing sarcoma (ES) can occur months or years after initial remission, and salvage therapy for relapsed disease is usually ineffective. Thus, there is great need to develop biomarkers that can predict which patients are at risk for relapse so that therapy and post‐therapy evaluation can be adjusted accordingly. For this study, we performed whole genome expression profiling on two independent cohorts of clinically annotated ES tumours in an effort to identify and validate prognostic gene signatures. ES specimens were obtained from the Children's Oncology Group and whole genome expression profiling performed using Affymetrix Human Exon 1.0 ST arrays. Lists of differentially expressed genes between survivors and non‐survivors were used to identify prognostic gene signatures. An independent cohort of tumours from the Euro‐Ewing cooperative group was similarly analysed as a validation cohort. Unsupervised clustering of gene expression data failed to segregate tumours based on outcome. Supervised analysis of survivors versus non‐survivors revealed a small number of differentially expressed genes and several statistically significant gene signatures. Gene‐specific enrichment analysis demonstrated that integrin and chemokine genes were associated with survival in tumours where stromal contamination was present. Tumours that did not harbour stromal contamination showed no association of any genes or pathways with clinical outcome. Our results reflect the challenges of performing RNA‐based assays on archived bone tumour specimens. In addition, they reveal a key role for tumour stroma in determining ES prognosis. Future biological and clinical investigations should focus on elucidating the contribution of tumour:micro‐environment interactions on ES progression and response to therapy.

Ewing sarcoma, a rare malignancy of childhood and adolescence, has become a model of advances in diagnosis, treatment, and outcome through long-standing research efforts in multinational clinical trials. With modern multimodal regimens consisting of local surgery and/or radiotherapy plus intensive systemic chemotherapy, survival can be achieved for ≈ 70% of patients with localized disease. However, in the last decade, improvement in survival curves has slowed down. Also, a relapse rate of ≈ 30% remains unacceptable, since salvage strategies for Ewing sarcoma recurrence are discouraging and prognosis is unfavorable in most cases. Metastatic disease at diagnosis poses a similar challenge, since even if remission is achieved, relapse frequently occurs despite the most intensive treatment. Urgently needed, novel biology-driven treatment options are now beginning to emerge on the horizon, but have not yet reached the standard of care. An overview of the current clinical state-of-the-art is provided in this article.