Background Infants with acute lymphoblastic leukemia (ALL) have a poor prognosis. Intensification of therapy has resulted in fewer relapses but increased early deaths, resulting in failure to improve survival. Procedure AALL0631 is a Phase 3 study for infants (< 366 days of age) with newly diagnosed ALL. Induction initially (Cohort 1) consisted of 3 weeks of therapy based on COG P9407. Due to excessive early mortality, induction was amended to a less intensive 5 weeks of therapy based on Interfant-99. Additionally, enhanced supportive care guidelines were incorporated with hospitalization during induction until evidence of marrow recovery and recommendations for prevention/treatment of infections (Cohort 2). Results Induction mortality was significantly lower for patients in Cohort 2 (2/123, 1.6%) versus Cohort 1 (4/26, 15.4%; p=0.009). All induction deaths were infection related except one due to progressive disease (Cohort 2). Sterile site infections were lower for patients in Cohort 2 (24/123, 19.5%) versus Cohort 1 (15/26, 57.7%; p=0.0002), with a significantly lower rate of Gram positive infections during induction for patients in Cohort 2, p=0.0002. No clinically significant differences in grades 3–5 non-infectious toxicities were observed between the two cohorts. Higher complete response rates were observed at end induction intensification for Cohort 2 (week 9, 94/100, 94%) versus Cohort 1 (week 7, 17/25, 68%; p=0.0.0012). Conclusion De-intensification of induction therapy and enhanced supportive care guidelines significantly decreased induction mortality and sterile site infections, without decreasing complete remission rates.

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Synthesis of high-purity biogenic heterocyclic library enabled identification of a small molecule, which potently inhibited proliferation of several cancer cell lines and induces rapid oxidative stress. This agent elicited unusual mechanism of cell death induction, which entailed activation of both caspase-dependent and independent pathways.

Identification of novel drug targets in ovarian cancers has focused on expression of genes in the tyrosine kinase family. We have previously shown that the spleen tyrosine kinase (SYK) gene was expressed in 73% of 55 ovarian cancer specimens, compared to 26% of 60 breast cancer specimens. Previous studies established the role of SYK in tumor progression. Among its many targets, SYK can bind microtubules and other molecules associated with the cytoskeleton. We found SYK to be expressed in 6 of 10 ovarian carcinoma cell lines. Because of the ability of SYK to bind to microtubules, we studied the relationship of SYK expression to cellular migration. We examined several ovarian cancer cell lines that variably express SYK to elucidate the potential effects of SYK on cell migration. Our results demonstrate that knockdown of SYK expression by siRNA resulted in a decreased capability of cells to migrate using a traditional wound scratch assay. The duration of this effect was dependant upon cell line used suggesting that additional protein targets may be involved in the migratory process. The potential effects of SYK expression on invasion are currently being investigated. We will evaluate potential upstream and downstream targets to elucidate the pathway(s) responsible for SYK effects and compare within the cell lines examined. Understanding the growth signals and proteins potentially responsible for invasion and metastasis in ovarian cancer cell lines and tumor samples may eventually lead to new therapeutic approaches for ovarian cancers. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1401. doi:10.1158/1538-7445.AM2011-1401

Taxanes are important drugs in the treatment of ovarian cancers, but their efficacy is limited by intrinsic and acquired drug resistance. Over-expression of the MDR1 gene and its product, P-glycoprotein, is a well-characterized resistance mechanism to taxanes, but non-MDR1 taxane resistance mechanisms are not well elucidated. To study the mechanisms of non-MDR1 multidrug resistance related to taxanes, we established multiple MDR1-negative and MDR1-positive taxane resistant variants from four ovarian cancer cell lines (A2780/1A9, ES-2, MES-OV and OVCAR-3) by continuous exposure of the cells to either paclitaxel or docetaxel with or without the P-glycoprotein inhibitor PSC-833 (Valspodar). We profiled gene expression and gene copy number alterations in these cell lines using cDNA microarrays, and identified a transcriptomic signature that predicts in vitro non-MDR1 resistance, a portion of which was imprinted by gene dosage changes. Functional network analyses for genes associated with the taxane resistance signature revealed two highly significant networks built around FN1 and CDKN1A which are associated with cell adhesion, cell-to-cell signaling and cell cycle regulation. We also identified epithelial-mesenchymal transition (EMT) marker genes which are significantly associated with non-MDR1 resistance. Migration potential in wound-scratch-assay was markedly enhanced in non-MDR1 resistant variants compared to parental cells. Our results suggest that ECM-interacting genes, EMT-like changes and cell cycle regulatory elements may play important roles in resistance to taxanes. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1526.

In order to identify novel drug targets in ovarian cancers, we examined our ovarian cancer gene expression microarray data for expression of genes in the tyrosine kinase family. The spleen tyrosine kinase (SYK) gene was expressed in 73% of 55 ovarian cancer specimens, compared to 26% of 60 breast cancer specimens. Previous studies established the role of SYK in lymphocyte development, immune cell activation, and tumor progression. We found SYK to be expressed in 6 of 10 ovarian carcinoma cell lines. Among its many targets, SYK can bind microtubules and other molecules associated with the cytoskeleton. Because of this ability, we studied the relationship of SYK expression to cellular sensitivity to taxanes. We focused on the OVCAR-3 cell line, which was one of the highest SYK-expressing cell lines, to elucidate the potential effects of SYK on taxane sensitivity. Our results demonstrate that knockdown of SYK expression by siRNA resulted in a one log-fold increased sensitivity of OVCAR-3 cells to the taxane, paclitaxel. Furthermore, this effect was durable, as knockdown of SYK and sensitization to paclitaxel persisted over 128 hours. The potential effects of SYK on tubulin polymerization are currently being investigated. We will evaluate potential upstream and downstream targets to elucidate the pathway(s) responsible for SYK effects and determine whether SYK levels contribute to tumor resistance to chemotherapeutic agents. Understanding the growth signals in drug sensitive and resistant ovarian cancer cell lines and tumor samples may eventually lead to new therapeutic approaches for ovarian cancers. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3496.

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MiRNAs are post-transcriptional regulators of cell proliferation, tissue differentiation, embryonic development and apoptosis. We profiled the expression of miRNAs in a panel of taxane-resistant human breast and ovarian cancer cell lines using the recently developed WaferGen SmartChip System. Four breast cancer cell lines (MCF-7, BT-549, MDA-MB-231 and T-47D) and four ovarian cancer cell lines (1A9/A2780, ES-2, MES-OV and OVCAR-3) were selected for resistance to either docetaxel or paclitaxel alone or co-selected with taxane in the presence of the P-glycoprotein inhibitor, PSC-833 (valspodar, 2 µM). All of the variants established by exposure to taxanes alone are MDR1/ABCB1(+), whereas the resistance observed in the co-selected variants is not transporter-mediated. We have previously reported elevated class III β-tubulin (TUBB3) content, reduced BRCA1 and elevated CDKN1A (p21) in the majority of the non-MDR1 taxane variants relative to parental controls. For miRNA profiling, total RNA was analyzed using the SmartChip Human MicroRNA Panel version 2.0 containing 1,150 unique real-time PCR reactions in quadruplicate for a total of ∼4,600 reactions per sample. Following ligation to a miRNA cloning linker (Integrated DNA Technology, Coraville, IA), the equivalent of 500 ng of starting RNA per sample was added to a one-step cDNA and real-time PCR cocktail (Applied Biosystems, Foster City, CA). The total volume per reaction was 100 nL containing an equivalent of 96 pg of RNA. Forty cycles of real-time PCR were performed on the SmartChip Cycler and a quality screen was performed to remove any outlier data. MiRNA profiling is complete and an analysis of these data revealed a clear separation between the two sets of non-MDR1 variants based on tumor type (breast vs. ovarian), and selection conditions (non-MDR1 vs. parental). We observed reduced miR-200 family expression in the majority of these taxane-resistant variants, consistent with published findings that miR-200c directly targets and suppresses TUBB3. Furthermore, Significance Analysis of Microarrays (SAM) software identified reduced miR-635, miR-296-3P, and let-7B in both MDR1(+) and MDR1(-) variants of breast origin, and elevated let-7 family (let-7B, let-7F and let-7I) and reduced miR-1225-5P and miR-4286 in the ovarian cell lines relative to parental controls. The functional significance of these observations will be studied by introducing miRNA inhibitors or mimics specific to key alterations with the goal of sensitizing cells to taxanes. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1095. doi:1538-7445.AM2012-1095