Nadine Houédé

Ipilimumab versus placebo after radiotherapy in patients with metastatic castration-resistant prostate cancer that had progressed after docetaxel chemotherapy (CA184-043): a multicentre, randomised, double-blind, phase 3 trial

BACKGROUND Ipilimumab is a fully human monoclonal antibody that binds cytotoxic T-lymphocyte antigen 4 to enhance antitumour immunity. Our aim was to assess the use of ipilimumab after radiotherapy in patients with metastatic castration-resistant prostate cancer that progressed after docetaxel chemotherapy. METHODS We did a multicentre, randomised, double-blind, phase 3 trial in which men with at least one bone metastasis from castration-resistant prostate cancer that had progressed after docetaxel treatment were randomly assigned in a 1:1 ratio to receive bone-directed radiotherapy (8 Gy in one fraction) followed by either ipilimumab 10 mg/kg or placebo every 3 weeks for up to four doses. Non-progressing patients could continue to receive ipilimumab at 10 mg/kg or placebo as maintenance therapy every 3 months until disease progression, unacceptable toxic effect, or death. Patients were randomly assigned to either treatment group via a minimisation algorithm, and stratified by Eastern Cooperative Oncology Group performance status, alkaline phosphatase concentration, haemoglobin concentration, and investigator site. Patients and investigators were masked to treatment allocation. The primary endpoint was overall survival, assessed in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT00861614. FINDINGS From May 26, 2009, to Feb 15, 2012, 799 patients were randomly assigned (399 to ipilimumab and 400 to placebo), all of whom were included in the intention-to-treat analysis. Median overall survival was 11·2 months (95% CI 9·5-12·7) with ipilimumab and 10·0 months (8·3-11·0) with placebo (hazard ratio [HR] 0·85, 0·72-1·00; p=0·053). However, the assessment of the proportional hazards assumption showed that it was violated (p=0·0031). A piecewise hazard model showed that the HR changed over time: the HR for 0-5 months was 1·46 (95% CI 1·10-1·95), for 5-12 months was 0·65 (0·50-0·85), and beyond 12 months was 0·60 (0·43-0·86). The most common grade 3-4 adverse events were immune-related, occurring in 101 (26%) patients in the ipilimumab group and 11 (3%) of patients in the placebo group. The most frequent grade 3-4 adverse events included diarrhoea (64 [16%] of 393 patients in the ipilimumab group vs seven [2%] of 396 in the placebo group), fatigue (40 [11%] vs 35 [9%]), anaemia (40 [10%] vs 43 [11%]), and colitis (18 [5%] vs 0). Four (1%) deaths occurred because of toxic effects of the study drug, all in the ipilimumab group. INTERPRETATION Although there was no significant difference between the ipilimumab group and the placebo group in terms of overall survival in the primary analysis, there were signs of activity with the drug that warrant further investigation. FUNDING Bristol-Myers Squibb.

Abstract 785: ETS-mediated expression of miR-24 regulates Top1 levels and resistance of prostate cancer cell lines to camptothecin

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Human nuclear topoisomerase I (Top1) is a crucial enzyme involved in the removal of DNA supercoiling during replication, transcription and chromosome segregation. These roles rely on its capability to introduce reversible single-strand breaks in duplex DNA. Top1 is the unique target of camptothecin (CPT) derivatives such as Irinotecan and Topotecan that are approved for the treatment of colon, ovarian and lung cancers. These inhibitors stabilize covalent Top1-DNA complexes resulting in cytotoxic double-strand breaks by collision of stabilized complexes with advancing replication forks. The mechanisms of resistance to CPT derivatives are complex and not fully understood yet, though it is known that the amount of Top1 can directly affect tumor cell response to these agents. Advanced forms of prostate cancers (PCa) that usually become resistant to castration are treated with chemotherapy using taxane-based regimen with disappointing response rates. Unfortunately, they also display an intrinsic resistance to many other cytotoxic agents including CPT derivatives. In this study, we identified one resistance mechanism linked to the regulation of Top1 levels via the overexpression of transcription factors from the ETS family (mainly ERG and ETV1) that is detected in 50-80% of PCa. We first showed that siRNA-mediated transient repression of ERG or ETV1 in ERG-overexpressing VCaP cells and in ETV1-overexpressing LNCaP cells, respectively, resulted in increased cell sensitivity to CPT, confirming the role of these two ETS transcription factors in PCa cell response to Top1 inhibitors. Using the CHiP-Seq database from UCSC, we could identify potential ETS binding domains in the promoter region of a cluster of miRNAs containing miR-24, which expression level across the NCI-60 cell line panel was found to be negatively correlated with the sensitivity to CPT derivatives. We then evaluated the modulation of miR-24 expression on cell sensitivity to CPT. We found that overexpression of miR-24 reduced sensitivity of LNCaP cells to CPT, whereas overexpression of an anti-miR-24 had the opposite effect, confirming previously published bioinformatics predictions. Interestingly, miR-24 overexpression in LNCaP cells was accompanied with a reduction in Top1 protein levels whereas transfection with anti-miR-24 resulted in increased Top1 levels. Together, our preliminary results provide the first functional evidences that Top1 levels and subsequent resistance of PCa cell lines to CPT are, at least in part, regulated via ETS-mediated expression of miR-24. They further represent a rational basis for the clinical development of miR-24 inhibitors for the sensitization of CPT-resistant tumors such as advanced PCa. Citation Format: Samer Kayali, Emmanuel Roche, Daniele Montaudon, Philippe Pourquier, Nadine Houede. ETS-mediated expression of miR-24 regulates Top1 levels and resistance of prostate cancer cell lines to camptothecin. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 785. doi:10.1158/1538-7445.AM2014-785

Formal Consensus Method to Evaluate the Conformity of Prescription of a Recently Approved Chemotherapy Treatment in an Observatory Study

Cabazitaxel is a second line chemotherapy drug recently approved for the treatment of metastatic castration-resistant prostate cancer. A first panel of French experts and a second independent panel of European experts were convened to assess the conformity of prescription of cabazitaxel with a Delphi consensus method. A two-round modified Delphi consensus process was conducted. This methodology is based on experts’ opinion obtained in a systematic manner. The process was divided into five steps: (i) elaboration of the questionnaire, (ii) rating, (iii) analysis, (iv) discussion of the points with absence of consensus following rating of the questionnaire, and (v) final reporting. Consensus was defined according to RAND method and all analyses were conducted according to the same methodology. At the end of the two rounds of rating and a synthesis meeting, of the 26 items included in the Summary of Product Characteristics (SPC), 11 items were judged appropriate with strong consensus by the two independent panels of experts. These items can therefore be considered of prime importance to evaluate conformity of cabazitaxel prescription in the context of observatory studies as well as in further clinical trials using this new taxane. Our findings further provide important evidence about the value of the Delphi consensus and highlight a requirement for “conformity” standards to assist practitioners in a safe chemotherapy drug prescription.

Identification of targeted therapy for an aggressive subgroup of muscle-invasive bladder cancers

Rebouissou et al. recently provided preclinical evidence that a subset of patients with muscle-invasive bladder cancer might benefit from anti-epidermal growth factor receptor (EGFR) therapy and reported diagnostic tools for identifying these patients in the clinical setting. This work also identified relevant experimental models that may be useful for future basic and clinical research on this subgroup of tumors.

Abstract 4478: SHMT2 modulates DNA methylation and differentially affects prostate cancer cell response to platinum derivatives.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Prostate cancer (PCa) is one of the leading causes of death from cancer in men. Several prognostic factors allow differentiating low-grade from high-grade PCa that are often refractory to chemical castration but are still treated with hormone therapy to which docetaxel or cabazitaxel are added when they become resistant to the anti-androgen. Despite many clinical trials with other chemotherapeutic agents, response rates remain low, pointing towards the need for new alternative therapies to treat these aggressive tumors. Using a rational in silico approach based on the NCI60-cell line panel, we recently identified a signature of 6 genes, the expression of which could predict at the functional level, sensitivity to oxaliplatin but not to cisplatin in DU145, LNCaP and C42B prostate cancer cell lines (Puyo et al. Mol. Pharmacol, 2012). Among them, we focused on SHMT2, the mitochondrial isoform of serine hydroxymethyl transferase involved in the biosynthesis of purines. Downregulation of SHMT2 or absence of SHMT2 catalytic activity was associated with a resistance to oxaliplatin, whereas it had no effect on cisplatin sensitivity, a selectivity that was attributed to the DACH moiety of platinum derivatives. Here, we investigated the role of DNA methylation in this selective response to platinum compounds since SHMTs can indirectly regulate the methylation status of DNA. Variations in global level of methylation as measured by the methylation status of LINE-1 retrotransposon, was associated with differences in sensitivity of PCa cells to platinum compounds. Using our in silico approach, we found significant correlations between SHMT2 expression and cell sensitivity to both demethylating agents azacytidine and decitabine. We also found that treatment of DU145 cells, with high level of global DNA methylation, sensitized cells to platinum compounds. In order to evaluate whether methylation could impair the formation of Pt-adducts in vitro, we used purified oligonucleotides containing a unique site of platination. We show that methylation at specific CpG in the vicinity of the platination site could reduce the kinetics of DNA adducts formation. This inhibition was more pronounced for DACH platin than for cisplatin. We also assessed the effect of transient repression of SHMT2 in LNCaP cells on the methylation status of ∼450,000 CpG sites using the Infinium Meth450K beadchip from Illumina. Preliminary results show that significant changes in methylation status was only observed in a reduced number of CpGs which were not located in genes that are known to be involved in cell response to Pt adducts formation. Together our results demonstrate that SHMT2-mediated specific response to oxaliplatin can be due to both methylation in the vicinity of the platination site and the modulation of the expression of genes that are not directly linked to the processing of DNA-adducts. Citation Format: Stephane Puyo, Nadine Houede, Marina Hamant, Pierre Richaud, Jacques Robert, Philippe Pourquier. SHMT2 modulates DNA methylation and differentially affects prostate cancer cell response to platinum derivatives. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4478. doi:10.1158/1538-7445.AM2013-4478

Abstract 5064: A gene expression signature which could predict high grade prostate cancer response to oxaliplatin

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Prostate cancer is one of the leading causes of death from cancer in men. The prognosis of patients is defined according to staging, PSA levels and Gleason score, which differentiates low grade (Gleason < 4) and high grade (Gleason ≥ 4) cancers. High-grade tumors are associated with high metastatic potential and poor prognosis. They are treated with hormone therapy, to which microtubule poisons are added when they become resistant to the anti-androgen. Despite many clinical trials with other chemotherapeutic agents, response rates remain low. Moreover, none of these trials took into account the tumor grade. We therefore envisaged a new rational in silico approach to screen for drug candidates that could be used as an alternative to docetaxel, based on an expression signature of 86 genes that could distinguish low-grade and high-grade tumors, with a reliability of 81% (PNAS 2006 103:10991-6). We explored the NCI databases, which allow access to both gene expression profiles of 60 human tumor cell lines and their in vitro sensitivity to thousands of anticancer drugs and extracted the expression profiles of the 86 genes’ signature. We calculated for each gene the Pearson coefficients of correlation (r) between their expression level in the 60 cell lines and cell sensitivity to 152 core anticancer compounds. We found that the expression of 11 genes was associated with sensitivity to oxaliplatin. They include DPM1, PCCB, ATP5G3, and SHMT2 genes involved in metabolism; RHOT2, CD59 and JUN genes involved in signal transduction, the CDKN2C cyclin-dependent kinase inhibitor gene, RPL13 and EIF4A1 genes involved in translation, and the unknown [FLJ35093][1] gene. This signature seems specific to DACH platinum derivatives since no correlation was found with the sensitivity to cisplatin. Functional validation of this signature was performed in vitro using the prostate cancer cell lines DU145 and LNCaP and the benign prostate hyperplasia (BPH) cells as “normal” cells. We measured the effect of siRNA-mediated downregulation of each of the 11 genes on the sensitivity to oxaliplatin or cisplatin by clonogenic or MTT assays. Preliminary data confirmed our in silico results for 7 out of the 11 genes, for which donwregulation induced a significant change in IC50 for oxaliplatin (but not cisplatin) in DU145 and/or LNCaP cells. For EIF4A1 we found a correlation opposite to that obtained from in silico results. Also, inhibition of CDKN2C could affect the sensitivity to cisplatin in LNCaP cells. Conversely, no effect of each siRNA tested could be observed in BPH cells, suggesting that functional validation should be tested in a tumoral background. Our new rational approach allowed the identification of oxaliplatin as an alternative therapy for high grade prostate cancers. It also identified a potential gene expression signature that could be used to predict tumor response to oxaliplatin (and potentially DACH platinum derivatives) in the clinic. 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 5064. doi:10.1158/1538-7445.AM2011-5064 [1]: /lookup/external-ref?link_type=GENPEPT&access_num=FLJ35093&atom=%2Fcanres%2F71%2F8_Supplement%2F5064.atom

Abstract 2692: Overexpression of serine hydroxy methyl transferase 2 (SHMT2) in high grade prostate cancers as a marker of tumor response to oxaliplatin

Prostate cancer is one of the leading causes of death from cancer in men and its incidence is constantly rising. In most cases, the prognosis of patients is defined according to staging, PSA levels and Gleason score, which differentiates low grade (Gleason 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 2692.