Abstract C104: High in vitro sensitivity of pediatric solid and hematological malignancies to the survivin-suppressant YM155.
Authors: Verschuur Arnauld C. , Lanvers-Kaminsky Claudia , Molenaar Jan J. , Lamers Fieke G. , Ouatas Taufik , Kita Aya , Boos Joachim , Vassal Gilles , Caron Huib C. 
Published: June 2012

Background: The aim of the Innovative Therapies for Children with Cancer (ITCC) consortium is to develop new drugs for the treatment of pediatric malignancies. It is composed of 35 pediatric oncology clinical centres in six European countries for early clinical trials and of 9 laboratories for preclinical evaluation of targeted anti-cancer compounds in pediatric cancer models. The aim of the preclinical ITCC biology program is to prioritize compounds for clinical development on the basis of in vitro/in vivo activity and relevance of biological targets. YM155 is an anticancer agent that suppresses survivin expression. YM155 has shown preclinical and clinical antitumor activity against a variety of adult solid tumors amongst others melanoma, NSCLC, HRPC as well as hematologic malignancies, B-NHL.

Material and methods: We investigated the in-vitro cytotoxicity of YM155 by the MTS-assay on the ITCC panel of 40 pediatric tumor cell lines, representing neuroblastoma (NBL), osteosarcoma (OS), rhabdomyosarcoma (RMS), Ewing sarcoma (ES), medulloblastoma (MB) and acute lymphocytic leukaemia (ALL). Cells were exposed for 48h to nine YM155 concentrations ranging from 0.001nM to 100μM. Experiments were performed in quadruplet and thrice. GI50 and LC50 were calculated according to standards. shRNA experiments targeting survivin (BIRC5) were performed on NBL cell lines and Western blot was used for survivin protein expression. Affymetrix gene expression data of the NBL cell lines were correlated to in vitro sensitivity to YM155.

Results: YM155 reduced the growth of all cell lines in a dose dependent manner. GI50s ranged from 0.12 nM to 10.08 μM with an overall mean of 587 nM. Highly sensitive cell lines with GI50s below 10 nM were 3 out of 7 NBL, 2/5 OS, 6/7 RMS, 3/7 ES, 1/5 MB, and 3/7 ALL cell lines. LC50s ≤ 100 nM of YM155 were observed for 3/7 NBL, 5/7 OS, 6/7 RMS, 4/7 ES cell lines, 1/5 MB and 5/7 ALL. Survivin shRNA plasmid knocked down survivin expression in NBL cell lines, inhibited the cell proliferation, and promoted cell apoptosis. Consistent with these results YM155 treatment induced survivin suppression and apoptosis. The differential expression of all 16,000 genes between the 5 most sensitive and 5 most insensitive NBL cell lines showed that MDR1 was the number one correlating gene. Cell lines with a high MDR1 expression were insensitive to YM155. Pretreatment with MDR-inhibitors restored the sensitivity to YM155.

Conclusion: YM155 is cytotoxic against pediatric tumor cell lines in vitro. Subtypes of RMS, NBL, OS, ES and ALL appear highly sensitive. YM155 treatment and/or BIRC5 gene knockdown leads to apoptosis. Resistance to YM155 may be caused by high MDR1-expression. This resistance is reversibke when combining with a MDR-inhibitor.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C104.