In vitro assessment of novel transcription inhibitors and topoisomerase poisons in rhabdomyosarcoma cell lines.

PURPOSE: Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children. Current chemotherapy regimes include the topoisomerase II poison etoposide and the transcription inhibitor actinomycin D. Poor clinical response necessitate identification of new agents to improve patient outcomes. METHODS: We assessed the in vitro cytotoxicity (MTT assay) of DNA intercalating agents in five established human RMS cell lines. These include novel classes of transcription inhibitors and topoisomerase poisons, previously shown to have potential as anti-cancer agents. RESULTS: Amongst the former agents, bisintercalating bis(9-aminoacridine-4-carboxamides) linked through the 9-position, and bis(phenazine-1-carboxamides) linked via their side chains, are compared with established transcription inhibitors. Amongst the latter, monofunctional acridine-4-carboxamides related to N-[2-(dimethylamino)ethyl]acridine-4-carboxamide, DACA, are compared with established topoisomerase poisons. CONCLUSIONS: Our findings specifically highlight the topoisomerase poison 9-amino-DACA, its 5-methylsulphone derivative, AS-DACA, and the bis(phenazine-1-carboxamide) transcription inhibitor MLN944/XR5944, currently in phase I trial, as candidates for further research into new agents for the treatment of RMS.

Alternative prognostic factors in pediatric embryonal rhabdomyosarcoma: Nm23 expression, proliferative activity and angiogenesis.

Possible clinical relevance of Nm23 expression, angiogenesis and proliferative activity were evaluated as prognostic parameters in childhood embryonal rhabdomyosarcoma (RMS). Specimens of 25 RMS cases were studied for Nm23 antigen immunohistochemically. Vascular surface density (VSD) and number of vessels per stroma (NVES) calculated by stereologic methods on labeling sections with CD34 antibody. For evaluation of proliferative activity of tumors, mitotic figures and Ki67 positive cells were investigated. All findings were searched statistically. Five patients were stage 1 (20%), two were stage 2 (8%), 15 were stage 3 (60%) and three were stage 4 (12%). The mean event free survival (EFS) was 20.8 and the mean overall survival (OS) was 25.9 months. Sixteen patients (64%) were alive and without disease. The percentage of Nm23 positivity was 52%. Log rank analysis showed Nm23 as a predictor for survival (p=0.0313). In Pearson correlation analysis, there was statistical significance between OS and presence of Nm23 expression (p=0.044). VSD was also positively related with EFS (p=0.040). Despite the present parameters in use, there is a need for new prognostic markers, especially to predict the outcome of patients. These findings suggested that Nm23 expression and VSD might be useful for follow-up in RMS.