Custirsen (OGX-011): clusterin inhibitor in metastatic prostate cancer

Hybrid Mouse Diversity Panel Identifies Genetic Architecture Associated with the Acute Antisense Oligonucleotide-Mediated Inflammatory Response to a 2'-O-Methoxyethyl Antisense Oligonucleotide

Although antisense oligonucleotides (ASOs) are well tolerated preclinically and in the clinic, some sequences of ASOs can trigger an inflammatory response leading to B cell and macrophage activation in rodents. This prompted our investigation into the contribution of genetic architecture to the ASO-mediated inflammatory response. Genome-wide association (GWA) and transcriptomic analysis in a hybrid mouse diversity panel (HMDP) were used to identify and validate novel genes involved in the acute and delayed inflammatory response to a single 75 mg/kg dose of an inflammatory 2'-O-methoxyethyl (2'MOE) modified ASO. The acute response was measured 6 h after ASO administration, via evaluation for increased plasma production of interleukin 6 (IL6), IL10, monocyte chemoattractant protein 1 (MCP-1) and macrophage inflammatory protein-1β (MIP-1β). Delayed inflammation was evaluated by spleen weight increases after 96 h. We identified single nucleotide polymorphisms (SNPs) on chromosomes 16 and 17 associated with plasma MIP-1β, IL6, and MCP-1 levels, and one on chromosome 8 associated with increases in spleen weight. Systems genetic analysis utilizing transcriptomic data from HMDP strain macrophages determined that the acute inflammatory SNPs were expression quantitative trait locis (eQTLs) for CCAAT/enhancer-binding protein beta (Cebpb) and salt inducible kinase 1 (Sik1). The delayed inflammatory SNP was an eQTL for Rho guanine nucleotide exchange factor 10 (Arhgef10). In vitro assays in mouse primary cells and human cell lines have confirmed the HMDP finding that lower Sik1 expression increases the acute inflammatory response. Our results demonstrate the utility of using mouse GWA study (GWAS) and the HMDP for detecting genes modulating the inflammatory response to pro-inflammatory ASOs in a pharmacological setting.

Meta-analysis of efficacy and safety of custirsen in patients with metastatic castration-resistant prostate cancer

Custirsen is the second-generation antisense oligonucleotide (ASO), which can reduce cellular levels of clusterin to increase the cytotoxic effect of chemotherapeutic drugs. Our study assessed the efficacy and safety of custirsen in patients with metastatic castration-resistant prostate cancer (mCRPC).We conducted a comprehensive search to identify all the randomized controlled trials (RCTs) of custirsen for the treatment of mCRPC. The reference lists of the retrieved studies were investigated.Three publications involving a total of 1709 patients were used in the analysis. We found that overall survival (OS) (P = .25) was not statistically significant in the comparison. Safety assessments indicated custirsen were often associated with complications resulting from neutropenia (P < .001), anaemia (P < .001), thrombocytopenia (P < .001), and diarrhea (P = .002).Our meta-analysis shows that custirsen has no obvious effect on improving the OS of patients with mCRPC. Adverse reactions were more common among those patients treated with custirsen as compared to those treated with placebo.

Mouse genome-wide association studies and systems genetics uncover the genetic architecture associated with hepatic pharmacokinetic and pharmacodynamic properties of a constrained ethyl antisense oligonucleotide targeting Malat1

Antisense oligonucleotides (ASOs) have demonstrated variation of efficacy in patient populations. This has prompted our investigation into the contribution of genetic architecture to ASO pharmacokinetics (PK) and pharmacodynamics (PD). Genome wide association (GWA) and transcriptomic analysis in a hybrid mouse diversity panel (HMDP) were used to identify and validate novel genes involved in the uptake and efficacy of a single dose of a Malat1 constrained ethyl (cEt) modified ASO. The GWA of the HMDP identified two significant associations on chromosomes 4 and 10 with hepatic Malat1 ASO concentrations. Stabilin 2 (Stab2) and vesicle associated membrane protein 3 (Vamp3) were identified by cis-eQTL analysis. HMDP strains with lower Stab2 expression and Stab2 KO mice displayed significantly lower PK than strains with higher Stab2 expression and the wild type (WT) animals respectively, confirming the role of Stab2 in regulating hepatic Malat1 ASO uptake. GWA examining ASO efficacy uncovered three loci associated with Malat1 potency: Small Subunit Processome Component (Utp11l) on chromosome 4, Rho associated coiled-coil containing protein kinase 2 (Rock2) and Aci-reductone dioxygenase (Adi1) on chromosome 12. Our results demonstrate the utility of mouse GWAS using the HMDP in detecting genes capable of impacting the uptake of ASOs, and identifies genes critical for the activity of ASOs in vivo.

Previous work in the clinic has clearly demonstrated differential patient response to antisense oligonucleotide (ASO) drugs. However, to date there has been no systematic evaluation of genes associated with this response in vivo. In this study, we utilized an advanced genetic methodology in mice to identify genes involved with the heterogeneity in both accumulation and potency of an ASO targeting metastasis associated lung adenocarcinoma transcript 1 (Malat1) in liver. Detailed analysis of ASO functionality in livers from 100 genetically distinct strains of inbred mice treated with either Malat1 or control ASO led to the selection of specific genetic regions associated with variation in ASO uptake and potency. Specifically, we identified regions on chromosomes 4 and 10 which highlighted two genes associated with variations in hepatic drug accumulation. Further, we established three regions on chromosome 4 and 12 linked to three genes associated with variability in hepatic ASO efficacy. We carried out additional functional validation of the isolated genes in mouse models and cell lines and confirmed that this methodology can be used to identify genes affecting ASO drug response. These results are particularly important for the design of antisense drugs with improved efficacy, safety, and tolerability.

Clusterin in Neuroendocrine Epithelial Neoplasms: Absence of Expression in a Well-differentiated Tumor Suggests a Jejunoileal Origin

Clusterin, a widely expressed, tissue-specific glycoprotein, is a diagnostic marker of several tumor types, including anaplastic large cell lymphoma, follicular dendritic cell sarcoma, and tenosynovial giant cell tumor. A recent study has suggested it is highly expressed by well-differentiated neuroendocrine tumors (NET) arising at most anatomic sites, with the exception of jejunoileal tumors, and that it is similarly not expressed by poorly differentiated neuroendocrine carcinomas (NEC). We sought to validate this result in a large cohort of NETs and NECs. Clusterin immunohistochemistry was performed on tissue microarrays of 255 NETs [45 lung, 4 stomach, 8 duodenum, 75 pancreas (62 primary, 13 metastatic), 107 jejunoileum (69 primary, 38 metastatic), 16 appendix] and 88 NECs (43 visceral, 45 Merkel cell). Extent (%) and intensity (0, 1+, 2+, 3+) of staining were assessed and an H-score (extent x intensity) calculated. An average H-score >5 was considered positive. Clusterin expression was noted in 82.4% of 148 nonjejunoileal NETs (average H-score 183) and only 8.4% of 107 jejunoileal NETs (average H-score, 31), as well as 19.3% of NECs (average H-score, 36). Clusterin is frequently, strongly expressed by NETs of diverse anatomic sites, with the exception of jejunoileal tumors, in which it is only rarely, weakly expressed. It is occasionally, weakly expressed by NECs. Most metastatic NETs of occult origin arise in the pancreas or the jejunoileum. For cases in which an initial site of origin immunopanel (eg, islet 1, PAX6, CDX2) is ambiguous, addition of clusterin may be diagnostically useful, with absence of expression suggesting a jejunoileal origin.

Effect of Targeting Clusterin Using OGX-011 on Antitumor Activity of Temsirolimus in a Human Renal Cell Carcinoma Model

BACKGROUND

It has not been well documented that the modulation of stress response mediates the efficacy of the mammalian target of rapamycin (mTOR) inhibitor in renal cell carcinoma (RCC).

OBJECTIVE

The objective of this study was to investigate whether the activity of the mTOR inhibitor temsirolimus against RCC could be enhanced by OGX-011, an antisense oligodeoxynucleotide (ODN) targeting the stress-activated chaperone clusterin.

METHODS

We investigated the efficacy of combined treatment with temsirolimus plus OGX-011 in a human RCC Caki-1 model focusing on the effects on apoptotic and autophagic pathways.

RESULTS

Although clusterin expression was increased by temsirolims, additional treatment of Caki-1 with OGX-011 significantly inhibited clusterin upregulation (p < 0.05). Combined treatment of temsirolimus and OGX-011 synergistically enhanced the sensitivity of Caki-1 to temsirolimus (p < 0.01), reducing the IC₅₀ by approximately 50 %. Apoptotic changes were marked in Caki-1 following combined treatment with a sublethal dose of temsirolimus and OGX-011, accompanying the significant downregulation of Mcl-1 (p < 0.05), but not with either agent alone. Furthermore, this combined treatment markedly blocked the temsirolimus-induced activation of autophagy in Caki-1 (p < 0.01). In-vivo systemic administration of temsirolimus plus OGX-011 significantly inhibited the growth of Caki-1 tumors compared with that of temsirolimus plus control ODN (p < 0.05).

CONCLUSIONS

Silencing of clusterin using OGX-011 resulted in the further enhancement of proapoptotic activity as well as the marked attenuation of the autophagic pathway induced by temsirolimus in a human RCC model. Thus, the combined use of OGX-011 could be a promising strategy through the enhanced cytotoxic activity of temsirolimus against RCC.

Clusterin, a gene enriched in intestinal stem cells, is required for L1-mediated colon cancer metastasis

Hyperactive Wnt signaling is a common feature in human colorectal cancer (CRC) cells. A central question is the identification and role of Wnt/β-catenin target genes in CRC and their relationship to genes enriched in colonic stem cells, since Lgr5+ intestinal stem cells were suggested to be the cell of CRC origin. Previously, we identified the neural immunoglobulin-like adhesion receptor L1 as a Wnt/β-catenin target gene localized in cells at the invasive front of CRC tissue and showed that L1 expression in CRC cells confers enhanced motility and liver metastasis. Here, we identified the clusterin (CLU) gene that is also enriched in Lgr5+ intestinal stem cells, as a gene induced during L1-mediated CRC metastasis. The increase in CLU levels by L1 in CRC cells resulted from transactivation of CLU by STAT-1. CLU overexpression in CRC cells enhanced their motility and the reduction in CLU levels in L1 overexpressing cells suppressed the ability of L1 to confer increased tumorigenesis and liver metastasis. Genes induced during L1-mediated CRC cell metastasis and enriched in intestinal stem cells might be important for both CRC progression and colonic epithelium homeostasis.

Making many from few: IL-12p40 as a model for the combinatorial assembly of heterodimeric cytokines

How dendritic cells (DCs) gather information from the local milieu at a site of infection or injury and communicate this to influence adaptive immunity is not well understood. We and others have reported that soon after microbial encounter, DCs secrete the p40 subunit of IL-12, by itself, in a monomeric form. Based on recent data that this p40 monomer subsequently associates with p35 released from other cells to generate functional IL-12, we proposed that p40 can function as a DC-derived probe which samples the composition of the local milieu by looking for other binding partners. In this opinion, we discuss how such a sampling function might generate an elaborate combinatorial "code" of heterodimeric cytokines, capable of conveying location-specific information to cells downstream of DC activation, including NK and T cells.

Chemotherapeutic inhibitors in the treatment of prostate cancer

INTRODUCTION

Prostate cancer being the second leading cause of death in men in Western countries remains a major challenge in healthcare. Several novel agents targeting signaling pathways in prostate cancer have recently been approved by the US Food and Drug Administration (FDA) but there is still an unmet need for new treatment strategies for castration-resistant prostate cancer (CRPC).

AREAS COVERED

This review provides a broad overview of prostate cancer therapeutics and highlights key players in the biology of prostate cancer as well as first- and second-line treatments for CRPC. Keywords 'chemotherapeutic agents', 'prostate cancer', 'Phase III clinical trials' and 'US FDA approval' were used for search in PubMed and clinicalTrials.gov databases and the obtained literature was reviewed and summarized.

EXPERT OPINION

Owing to the advances in screening and diagnostic techniques, the majority of prostate cancer cases are diagnosed at an early stage resulting in an almost 100% 5-year survival rate. Recently FDA-approved novel agents (e.g., abiraterone acetate and enzalutamide) have provided new hope in the fight against prostate cancer. However, CRPC remains an incurable disease. Identification of mechanisms of resistance, new biomarkers, appropriate clinical trial end points and novel treatments holds the key for the future of prostate cancer therapy.

Antisense technology: an emerging platform for cardiovascular disease therapeutics

Antisense oligonucleotides and small interfering RNAs, which suppress the translation of specific mRNA target proteins, are emerging as important therapeutic modalities for the treatment of cardiovascular disease. Over the last 25 years, the advances in all aspects of antisense technology, as well as a detailed understanding of the mechanism of action of antisense drugs, have enabled their use as therapeutic agents. These advancements culminated in the FDA approval of the first chronically administered cardiovascular antisense therapeutic, mipomersen, which targets hepatic apolipoprotein B mRNA. This review provides a brief history of antisense technology, highlights the progression of mipomersen from preclinical studies to multiple Phase III registration trials, and gives an update on the status of other cardiovascular antisense therapeutics currently in the clinic.