A phase I pharmacokinetic and pharmacodynamic study of OGX-011, a 2'-methoxyethyl antisense oligonucleotide to clusterin, in patients with localized prostate cancer

Clusterin: a marker and mediator of chemoresistance in colorectal cancer

Intra-tumoural heterogeneity and cancer cell plasticity in colorectal cancer (CRC) have been key challenges to effective treatment for patients. It has been suggested that a subpopulation of LGR5-expressing cancer stem cells (CSCs) is responsible for driving tumour relapse and therapy resistance in CRC. However, studies have revealed that the LGR5+ve CSC population is highly sensitive to chemotherapy. It has been hypothesised that another subset of tumour cells can phenotypically revert to a stem-like state in response to chemotherapy treatment which replenishes the LGR5+ve CSC population and maintains tumour growth. Recently, a unique stem cell population marked by enriched clusterin (CLU) expression and termed the revival stem cell (RevSC) was identified in the regenerating murine intestine. This CLU-expressing cell population is quiescent during homeostasis but has the ability to survive and regenerate other stem cells upon injury. More recently, the CLU+ve signature has been implicated in several adverse outcomes in CRC, including chemotherapy resistance and poor patient survival; however, the mechanism behind this remains undetermined. In this review, we discuss recent insights on CLU in CRC and its roles in enhancing the plasticity of cells and further consider the implications of CLU as a prospective target for therapeutic intervention.

The safety and toxicity profile of SPL84, an inhaled antisense oligonucleotide for treatment of cystic fibrosis patients with the 3849 +10kb C->T mutation, supports a Phase 1/2 clinical study

INTRODUCTION

SPL84 is an inhaled antisense oligonucleotide (ASO) in development for the treatment of cystic fibrosis (CF) patients carrying the 3849 + 10kb C->T (3849) mutation. To support the initiation of the first clinical study, a full battery of safety and toxicology studies were performed.

RESEARCH DESIGN AND METHODS

SPL84 was administered by inhalation to mice and monkeys to determine the no observed adverse effect level (NOAEL) and establish sufficient safety margins for the starting clinical dose.

RESULTS

There were no preclinical safety findings with SPL84; no related clinical signs, nor any effect on body weight, food consumption, or clinical pathology. The microscopic changes in the lungs were regarded as non-adverse and reflected a normal clearance process for inhaled compounds. Systemic exposure in both species was low. The NOAEL for mice and monkeys was the highest administered dose in both species, resulting in safety margins ~ 40X the proposed starting clinical dose.

CONCLUSION

These successful results supported the initiation of a phase 1/2 clinical study of SPL84 (ongoing), assessing the safety, tolerability, and pharmacokinetics of a single ascending dose in healthy subjects to be followed by assessment of safety, tolerability, pharmacokinetics, and preliminary efficacy of multiple ascending doses in CF patients carrying the 3849 mutation.

Non-coding RNAs in human health and disease: potential function as biomarkers and therapeutic targets

Human diseases have been a critical threat from the beginning of human history. Knowing the origin, course of action and treatment of any disease state is essential. A microscopic approach to the molecular field is a more coherent and accurate way to explore the mechanism, progression, and therapy with the introduction and evolution of technology than a macroscopic approach. Non-coding RNAs (ncRNAs) play increasingly important roles in detecting, developing, and treating all abnormalities related to physiology, pathology, genetics, epigenetics, cancer, and developmental diseases. Noncoding RNAs are becoming increasingly crucial as powerful, multipurpose regulators of all biological processes. Parallel to this, a rising amount of scientific information has revealed links between abnormal noncoding RNA expression and human disorders. Numerous non-coding transcripts with unknown functions have been found in addition to advancements in RNA-sequencing methods. Non-coding linear RNAs come in a variety of forms, including circular RNAs with a continuous closed loop (circRNA), long non-coding RNAs (lncRNA), and microRNAs (miRNA). This comprises specific information on their biogenesis, mode of action, physiological function, and significance concerning disease (such as cancer or cardiovascular diseases and others). This study review focuses on non-coding RNA as specific biomarkers and novel therapeutic targets.

Current Advances in RNA Therapeutics for Human Diseases

Following the discovery of nucleic acids by Friedrich Miescher in 1868, DNA and RNA were recognized as the genetic code containing the necessary information for proper cell functioning. In the years following these discoveries, vast knowledge of the seemingly endless roles of RNA have become better understood. Additionally, many new types of RNAs were discovered that seemed to have no coding properties (non-coding RNAs), such as microRNAs (miRNAs). The discovery of these new RNAs created a new avenue for treating various human diseases. However, RNA is relatively unstable and is degraded fairly rapidly once administered; this has led to the development of novel delivery mechanisms, such as nanoparticles to increase stability as well as to prevent off-target effects of these molecules. Current advances in RNA-based therapies have substantial promise in treating and preventing many human diseases and disorders through fixing the pathology instead of merely treating the symptomology similarly to traditional therapeutics. Although many RNA therapeutics have made it to clinical trials, only a few have been FDA approved thus far. Additionally, the results of clinical trials for RNA therapeutics have been ambivalent to date, with some studies demonstrating potent efficacy, whereas others have limited effectiveness and/or toxicity. Momentum is building in the clinic for RNA therapeutics; future clinical care of human diseases will likely comprise promising RNA therapeutics. This review focuses on the current advances of RNA therapeutics and addresses current challenges with their development.

Antisense Oligonucleotide-Mediated Splice Switching: Potential Therapeutic Approach for Cancer Mitigation

Splicing is an essential process wherein precursor messenger RNA (pre-mRNA) is reshaped into mature mRNA. In alternative splicing, exons of any pre-mRNA get rearranged to form mRNA variants and subsequently protein isoforms, which are distinct both by structure and function. On the other hand, aberrant splicing is the cause of many disorders, including cancer. In the past few decades, developments in the understanding of the underlying biological basis for cancer progression and therapeutic resistance have identified many oncogenes as well as carcinogenic splice variants of essential genes. These transcripts are involved in various cellular processes, such as apoptosis, cell signaling and proliferation. Strategies to inhibit these carcinogenic isoforms at the mRNA level are promising. Antisense oligonucleotides (AOs) have been developed to inhibit the production of alternatively spliced carcinogenic isoforms through splice modulation or mRNA degradation. AOs can also be used to induce splice switching, where the expression of an oncogenic protein can be inhibited by the induction of a premature stop codon. In general, AOs are modified chemically to increase their stability and binding affinity. One of the major concerns with AOs is efficient delivery. Strategies for the delivery of AOs are constantly being evolved to facilitate the entry of AOs into cells. In this review, the different chemical modifications employed and delivery strategies applied are discussed. In addition to that various AOs in clinical trials and their efficacy are discussed herein with a focus on six distinct studies that use AO-mediated exon skipping as a therapeutic strategy to combat cancer.

Nucleic Acid Drugs-Current Status, Issues, and Expectations for Exosomes

Simple Summary

Nucleic acid drugs provide novel therapeutic modalities with characteristics that differ from those of small molecules and antibodies. In this review, I focus on the various mechanisms through which nucleic acid drugs act on, the status of their clinical development, and discuss several hurdles that need to be surmounted. In addition, by listing examples of how the progress in exosome biology can lead to the solution of problems in nucleic acid drug therapy, I hope that many more nucleic acid drugs including anticancer drugs will be developed in the future.

Abstract

Nucleic acid drugs are being developed as novel therapeutic modalities. They have great potential to treat human diseases such as cancers, viral infections, and genetic disorders due to unique characteristics that make it possible to approach undruggable targets using classical small molecule or protein/antibody-based biologics. In this review, I describe the advantages, classification, and clinical status of nucleic acid therapeutics. To date, more than 10 products have been launched, and many products have been tested in clinics. To promote the use of nucleic acid therapeutics such as antibodies, several hurdles need to be surmounted. The most important issue is the delivery of nucleic acids and several other challenges have been reported. Recent advanced delivery platforms are lipid nanoparticles and ligand conjugation approaches. With the progress of exosome biology, exosomes are expected to contribute to the solution of various problems associated with nucleic acid drugs.

Chemistry of Peptide-Oligonucleotide Conjugates: A Review

Peptide-oligonucleotide conjugates (POCs) represent one of the increasingly successful albeit costly approaches to increasing the cellular uptake, tissue delivery, bioavailability, and, thus, overall efficiency of therapeutic nucleic acids, such as, antisense oligonucleotides and small interfering RNAs. This review puts the subject of chemical synthesis of POCs into the wider context of therapeutic oligonucleotides and the problem of nucleic acid drug delivery, cell-penetrating peptide structural types, the mechanisms of their intracellular transport, and the ways of application, which include the formation of non-covalent complexes with oligonucleotides (peptide additives) or covalent conjugation. The main strategies for the synthesis of POCs are viewed in detail, which are conceptually divided into (a) the stepwise solid-phase synthesis approach and (b) post-synthetic conjugation either in solution or on the solid phase, especially by means of various click chemistries. The relative advantages and disadvantages of both strategies are discussed and compared.

Antisense Tissue Factor Oligodeoxynucleotides Protected Diethyl Nitrosamine/Carbon Tetrachloride-Induced Liver Fibrosis Through Toll Like Receptor4-Tissue Factor-Protease Activated Receptor1 Pathway

Tissue factor (TF) is a blood coagulation factor that has several roles in many non-coagulant pathways involved in different pathological conditions such as angiogenesis, inflammation and fibrogenesis. Coagulation and inflammation are crosslinked with liver fibrosis where protease-activated receptor1 (PAR1) and toll-like receptor4 (TLR4) play a key role. Antisense oligodeoxynucleotides are strong modulators of gene expression. In the present study, antisense TF oligodeoxynucleotides (TFAS) was evaluated in treating liver fibrosis via suppression of TF gene expression. Liver fibrosis was induced in rats by a single administration of N-diethyl nitrosamine (DEN, 200 mg/kg; i. p.) followed by carbon tetrachloride (CCl4, 3 ml/kg; s. c.) once weekly for 6 weeks. Following fibrosis induction, liver TF expression was significantly upregulated along with liver enzymes activities and liver histopathological deterioration. Alpha smooth muscle actin (α-SMA) and transforming growth factor-1beta (TGF-1β) expression, tumor necrosis factor-alpha (TNF-α) and hydroxyproline content and collagen deposition were significantly elevated in the liver. Blocking of TF expression by TFAS injection (2.8 mg/kg; s. c.) once weekly for 6 weeks significantly restored liver enzymes activities and improved histopathological features along with decreasing the elevated α-SMA, TGF-1β, TNF-α, hydroxyproline and collagen. Moreover, TFAS decreased the expression of both PAR1 and TLR4 that were induced by liver fibrosis. In conclusion, we reported that blockage of TF expression by TFAS improved inflammatory and fibrotic changes associated with CCl4+DEN intoxication. In addition, we explored the potential crosslink between the TF, PAR1 and TLR4 in liver fibrogenesis. These findings offer a platform on which recovery from liver fibrosis could be mediated through targeting TF expression.

The long non-coding RNA GHSROS reprograms prostate cancer cell lines toward a more aggressive phenotype

It is now appreciated that long non-coding RNAs (lncRNAs) are important players in orchestrating cancer progression. In this study we characterized GHSROS, a human lncRNA gene on the opposite DNA strand (antisense) to the ghrelin receptor gene, in prostate cancer. The lncRNA was upregulated by prostate tumors from different clinical datasets. Transcriptome data revealed that GHSROS alters the expression of cancer-associated genes. Functional analyses in vitro showed that GHSROS mediates tumor growth, migration and survival, and resistance to the cytotoxic drug docetaxel. Increased cellular proliferation of GHSROS-overexpressing PC3, DU145, and LNCaP prostate cancer cell lines in vitro was recapitulated in a subcutaneous xenograft model. Conversely, in vitro antisense oligonucleotide inhibition of the lncRNA reciprocally regulated cell growth and migration, and gene expression. Notably, GHSROS modulates the expression of PPP2R2C, the loss of which may drive androgen receptor pathway-independent prostate tumor progression in a subset of prostate cancers. Collectively, our findings suggest that GHSROS can reprogram prostate cancer cells toward a more aggressive phenotype and that this lncRNA may represent a potential therapeutic target.

Clusterin as modulator of carcinogenesis: A potential avenue for targeted cancer therapy

Clusterin (CLU) is an evolutionary conserved molecular chaperone present in different human tissues and fluids and established to be a significant cancer regulator. It controls several cancer-associated cellular events, including cancer cell proliferation, stemness, survival, metastasis, epithelial-mesenchymal transition, therapy resistance, and inhibition of programmed cell death to support cancer growth and recurrence. This multifunctional role of CLU makes it an ideal target for cancer control. More importantly, genetic and antisense-mediated (OGX-011) inhibition of CLU enhances the anticancer potential of different FDA-approved chemotherapeutic drugs at the clinical level, improving patient's survival. In this review, we have discussed the detailed mechanism of CLU-mediated modulation of different cancer-associated signaling pathways. We have also provided updated information on the current preclinical and clinical findings that drive trials in various cancer types for potential targeted cancer therapy.

Opportunities and challenges for the clinical translation of structured DNA assemblies as gene therapeutic delivery and vaccine vectors

Gene therapeutics including siRNAs, anti‐sense oligos, messenger RNAs, and CRISPR ribonucleoprotein complexes offer unmet potential to treat over 7,000 known genetic diseases, as well as cancer, through targeted in vivo modulation of aberrant gene expression and immune cell activation. Compared with viral vectors, nonviral delivery vectors offer controlled immunogenicity and low manufacturing cost, yet suffer from limitations in toxicity, targeting, and transduction efficiency. Structured DNA assemblies fabricated using the principle of scaffolded DNA origami offer a new nonviral delivery vector with intrinsic, yet controllable immunostimulatory properties and virus‐like spatial presentation of ligands and immunogens for cell‐specific targeting, activation, and control over intracellular trafficking, in addition to low manufacturing cost. However, the relative utilities and limitations of these vectors must clearly be demonstrated in preclinical studies for their clinical potential to be realized. Here, we review the major capabilities, opportunities, and challenges we foresee in translating these next‐generation delivery and vaccine vectors to the clinic.

This article is categorized under:

Therapeutic Approaches and Drug Discovery > Emerging Technologies

Biology‐Inspired Nanomaterials > Nucleic Acid‐Based Structures

Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease

Apolipoproteins and cancer

The role of apolipoproteins in cardiovascular disease has been well investigated, but their participation in cancer has only been explored in a few published studies which showed a close link with certain kinds of cancer. In this review, we focused on the function of different kinds of apolipoproteins in cancers, autophagy, oxidative stress, and drug resistance. The potential application of apolipoproteins as biomarkers for cancer diagnosis and prognosis was highlighted, together with an investigation of their potential as drug targets for cancer treatment. Many important roles of apolipoproteins and their mechanisms in cancers were reviewed in detail and future perspectives of apolipoprotein research were discussed.

The Multiple Roles and Therapeutic Potential of Molecular Chaperones in Prostate Cancer

Prostate cancer (PCa) is one of the most common cancer types in men worldwide. Heat shock proteins (HSPs) are molecular chaperones that are widely implicated in the pathogenesis, diagnosis, prognosis, and treatment of many cancers. The role of HSPs in PCa is complex and their expression has been linked to the progression and aggressiveness of the tumor. Prominent chaperones, including HSP90 and HSP70, are involved in the folding and trafficking of critical cancer-related proteins. Other members of HSPs, including HSP27 and HSP60, have been considered as promising biomarkers, similar to prostate-specific membrane antigen (PSMA), for PCa screening in order to evaluate and monitor the progression or recurrence of the disease. Moreover, expression level of chaperones like clusterin has been shown to correlate directly with the prostate tumor grade. Hence, targeting HSPs in PCa has been suggested as a promising strategy for cancer therapy. In the current review, we discuss the functions as well as the role of HSPs in PCa progression and further evaluate the approach of inhibiting HSPs as a cancer treatment strategy.

Clusterin in Alzheimer's Disease: Mechanisms, Genetics, and Lessons From Other Pathologies

Clusterin (CLU) or APOJ is a multifunctional glycoprotein that has been implicated in several physiological and pathological states, including Alzheimer's disease (AD). With a prominent extracellular chaperone function, additional roles have been discussed for clusterin, including lipid transport and immune modulation, and it is involved in pathways common to several diseases such as cell death and survival, oxidative stress, and proteotoxic stress. Although clusterin is normally a secreted protein, it has also been found intracellularly under certain stress conditions. Multiple hypotheses have been proposed regarding the origin of intracellular clusterin, including specific biogenic processes leading to alternative transcripts and protein isoforms, but these lines of research are incomplete and contradictory. Current consensus is that intracellular clusterin is most likely to have exited the secretory pathway at some point or to have re-entered the cell after secretion. Clusterin's relationship with amyloid beta (Aβ) has been of great interest to the AD field, including clusterin's apparent role in altering Aβ aggregation and/or clearance. Additionally, clusterin has been more recently identified as a mediator of Aβ toxicity, as evidenced by the neuroprotective effect of CLU knockdown and knockout in rodent and human iPSC-derived neurons. CLU is also the third most significant genetic risk factor for late onset AD and several variants have been identified in CLU. Although the exact contribution of these variants to altered AD risk is unclear, some have been linked to altered CLU expression at both mRNA and protein levels, altered cognitive and memory function, and altered brain structure. The apparent complexity of clusterin's biogenesis, the lack of clarity over the origin of the intracellular clusterin species, and the number of pathophysiological functions attributed to clusterin have all contributed to the challenge of understanding the role of clusterin in AD pathophysiology. Here, we highlight clusterin's relevance to AD by discussing the evidence linking clusterin to AD, as well as drawing parallels on how the role of clusterin in other diseases and pathways may help us understand its biological function(s) in association with AD.

Inhibition of HBsAg secretion by nucleic acid polymers in HepG2.2.15 cells

More than 290 million people have chronic HBV infection and are at risk of developing cirrhosis and hepatocellular carcinoma. HBV subviral particles are produced in large excess over virions in infected patients and are the primary source of HBsAg, which is postulated to be important in allowing HBV to chronically persist by interfering with immune function. Nucleic acid polymers (NAPs) have been shown to result in clearance of HBsAg from the blood in pre-clinical and clinical studies. In this study, we show for the first time the recapitulation of NAP- induced inhibition of secretion of HBsAg in vitro using the human HepG2.2.15 cell line. With the restoration of endosomal release of NAPs in vitro using the UNC7938 compound, NAPs were observed to selectively impair the secretion of HBsAg without any intracellular HBsAg accumulation. Additionally, the structure-activity relationship of NAPs for this antiviral activity is similar to that previously reported in other infectious diseases and identifies an exposed hydrophobic protein domain as the target interface for this antiviral effect. The presented in vitro model, the first one to be based on a human derived cell line that constitutively expresses HBV, is a very promising tool for the identification of the host proteins(s) targeted by NAPs.

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.

New Opportunities for Targeting the Androgen Receptor in Prostate Cancer

Recent genomic analyses of metastatic prostate cancer have provided important insight into adaptive changes in androgen receptor (AR) signaling that underpin resistance to androgen deprivation therapies. Novel strategies are required to circumvent these AR-mediated resistance mechanisms and thereby improve prostate cancer survival. In this review, we present a summary of AR structure and function and discuss mechanisms of AR-mediated therapy resistance that represent important areas of focus for the development of new therapies.

Current Challenges in Delivery and Cytosolic Translocation of Therapeutic RNAs

RNA interference (RNAi) is a fundamental cellular process for the posttranscriptional regulation of gene expression. RNAi can exogenously be modulated by small RNA oligonucleotides, such as microRNAs (miRNAs) and small interfering RNAs (siRNAs), or by antisense oligonucleotides. These small oligonucleotides provided the scientific community with powerful and versatile tools to turn off the expression of genes of interest, and hold out the promise of new therapeutic solutions against a wide range of gene-associated pathologies. However, unmodified nucleic acids are highly instable in biological systems, and their weak interaction with plasma proteins confers an unfavorable pharmacokinetics. In this review, we first provide an overview of the most efficient chemical strategies that, over the past 30 years, have been used to significantly improve the therapeutic potential of oligonucleotides. Oligonucleotides targeting and delivery technologies are then presented, including covalent conjugates between oligonucleotides and targeting ligand, and noncovalent association with lipid or polymer nanoparticles. Finally, we specifically focus on the endosomal escape step, which represents a major stumbling block for the effective use of oligonucleotides as therapeutic agents. The need for approaches to quantitatively measure endosomal escape and cytosolic arrival of biomolecules is discussed in the context of the development of efficient oligonucleotide targeting and delivery vectors.

RNA Therapeutics in Oncology: Advances, Challenges, and Future Directions

RNA-based therapeutic technologies represent a rapidly expanding class of therapeutic opportunities with the power to modulate cellular biology in ways never before possible. With RNA-targeted therapeutics, inhibitors of previously undruggable proteins, gene expression modulators, and even therapeutic proteins can be rationally designed based on sequence information alone, something that is not possible with other therapeutic modalities. The most advanced RNA therapeutic modalities are antisense oligonucleotides (ASOs) and small interfering RNAs. Particularly with ASOs, recent clinical data have demonstrated proof of mechanism and clinical benefit with these approaches across several nononcology disease areas by multiple routes of administration. In cancer, next-generation ASOs have recently demonstrated single-agent activity in patients with highly refractory cancers. Here we discuss advances in RNA therapeutics for the treatment of cancer and the challenges that remain to solidify these as mainstay therapeutic modalities to bridge the pharmacogenomic divide that remains in cancer drug discovery.

Clusterin inhibition mediates sensitivity to chemotherapy and radiotherapy in human cancer

Since its discovery in 1983, the protein clusterin (CLU) has been isolated from almost all human tissues and fluids and linked to the development of different physiopathological processes, including carcinogenesis and tumor progression. During the last few years, several studies have shown the cytoprotective role of secretory CLU in tumor cells, inhibiting their apoptosis and enhancing their resistance to conventional treatments including hormone depletion, chemotherapy, and radiotherapy. In an effort to determine the therapeutic potential that the inhibition of this protein could have on the development of new strategies for cancer treatment, numerous studies have been carried out in this field, with results, in most cases, satisfactory but sometimes contradictory. In this document, we summarize for the first time the current knowledge of the effects that CLU inhibition has on sensitizing tumor cells to conventional cancer treatments and discuss its importance in the development of new strategies against cancer.

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.

Custirsen (OGX-011) combined with cabazitaxel and prednisone versus cabazitaxel and prednisone alone in patients with metastatic castration-resistant prostate cancer previously treated with docetaxel (AFFINITY): a randomised, open-label, international, phase 3 trial

BACKGROUND

Docetaxel and cabazitaxel improve overall survival compared with mitoxantrone in patients with metastatic castration-resistant prostate cancer. Custirsen (OGX011) is a second generation highly specific antisense oligonucleotide that inhibits the production of clusterin, an antiapoptotic protein that is upregulated in response to chemotherapy and that confers treatment resistance. We aimed to assess whether custirsen in combination with cabazitaxel and prednisone increases overall survival in patients with metastatic castration-resistant prostate cancer previously treated with docetaxel.

METHODS

In this randomised, open-label, international, phase 3 trial, men with radiographically documented metastatic castration-resistant prostate cancer that had progressed after docetaxel treatment with a Karnofsky performance status of more than 70% and who were fit for chemotherapy, were recruited from 95 cancer treatment centres in eight countries. Patients were randomly assigned (1:1) centrally using permuted blocks (block size 8) to receive cabazitaxel plus prednisone (cabazitaxel 25 mg/m² intravenously every 21 days plus oral prednisone 10 mg daily) with or without custirsen (640 mg intravenously on days 1, 8, and 15, plus three previous loading doses) until disease progression, unacceptable toxicity, or the completion of ten treatment cycles. Randomisation was stratified by use of opioids for prostate cancer-related pain at screening, disease progression following first-line docetaxel treatment established by radiographic evidence, and previous treatment with abiraterone or enzalutamide. The co-primary endpoints were overall survival in all randomly assigned patients and in a poor-prognosis subgroup. All analyses were intention to treat with the exception of safety, which was reported for patients who received any assigned treatment. The trial has been completed and the results presented here are the final analysis. This trial is registered with Clinicaltrials.gov, number NCT01578655.

FINDINGS

Between Sept 9, 2012, and Sept 29, 2014, 795 patients were screened for enrolment. 635 men were eligible for inclusion and were randomly assigned (n=317 in the cabazitaxel and prednisone plus custirsen group and n=318 in the cabazitaxel and prednisone group). Median follow up was 28·3 months (IQR 24·4-34·5) for the custirsen group and 29·8 months (IQR 25·3-35·2) for the control group. Median overall survival in all randomly assigned patients did not differ between the two groups (14·1 months [95% CI 12·7-15·9] in the curtisen group vs 13·4 months [12·1-14·9] in the control group; hazard ratio [HR] 0·95 [95% CI 0·80-1·12]; log-rank p=0·53). In the poor prognosis subgroup, median overall survival also did not differ between the two treatment groups (11·0 months [95% CI 9·3-13·3] in the custursin group vs 10·9 months [8·2-12·4] in the control group; HR 0·97 [95% CI 0·80-1·21]; two-sided p=0·80). The most frequently reported grade 3 or worse adverse events in the custirsen versus control groups were neutropenia (70 [22%] of 315 vs 61 [20%] of 312), anaemia (68 [22%] vs 49 [16%]), fatigue (23 [7%] vs 18 [6%]), asthenia (16 [5%] vs 8 [3%]), bone pain (16 [5%] vs 5 [2%]), and febrile neutropenia (16 [5%] vs 9 [3%]). Serious adverse events were reported in 155 (49%) versus 132 (42%). 27 patients died within 30 days of treatment in the cabazitaxel and prednisone plus custirsen group, seven of which were deemed to be treatment related, versus 17 in the cabazitaxel and prednisone group, eight of which were deemed to be treatment related. Of the 21 deaths reported, 15 were reported as complications related to study treatment, either chemotherapy (eight and three, respectively) or study drug (none and four, respectively).

INTERPRETATION

We noted no survival benefit in men with metastatic castration-resistant prostate cancer with the addition of custirsen to cabazitaxel and prednisone treatment. Cabazitaxel and prednisone remains the standard of care for patients with metastatic castration-resistant prostate cancer progressing after docetaxel chemotherapy.

FUNDING

OncoGenex Pharmaceuticals.

A population pharmacokinetic meta-analysis of custirsen, an antisense oligonucleotide, in oncology patients and healthy subjects

AIMS

Custirsen (OGX-011/TV-1011), a second-generation antisense oligonucleotide that reduces clusterin production, is under investigation with chemotherapy in prostate and lung cancer. This meta-analysis evaluated the population pharmacokinetics (PK) of custirsen in cancer patients and healthy subjects.

METHODS

The population PK analysis used custirsen plasma concentrations from five Phase 1 studies, one Phase 1/2 study, and one Phase 3 study in two stages. Cancer patients received multiple doses of custirsen (40-640 mg intravenously over 120 min) with chemotherapy; healthy subjects received single or multiple doses (320-640 mg). An interim population PK model was developed using a nonlinear mixed-effect approach incorporating data from four Phase 1 or 1/2 studies, followed by model refinement and inclusion of two Phase 1 and one Phase 3 studies.

RESULTS

The final model was developed with 5588 concentrations from 631 subjects with doses of 160-640 mg. Custirsen PK was adequately described by a three-compartment model with first-order elimination. For a representative 66-year-old individual with body weight 82 kg and serum creatinine level 0.933 mg dl^-1 , the estimated typical (95% CI) parameter values were clearance (CL) = 2.36 (2.30-2.42) l h^-1 , central volume of distribution (V₁ ) = 6.08 (5.93-6.23) l, peripheral volume of distribution (V₂ ) = 1.13 (1.01-1.25) l, volume of the second peripheral compartment (V₃ ) = 15.8 (14.6-17.0) l, inter-compartmental clearance Q₂ = 0.0755 (0.0689-0.0821) l h^-1 , and Q₃ = 0.0573 (0.0532-0.0614) l h^-1 . Age, weight and serum creatinine were predictors of CL; age was a predictor of Q₃ .

CONCLUSION

A population PK model for custirsen was successfully developed in cancer patients and healthy subjects, including covariates contributing to variability in custirsen PK.

Custirsen in combination with docetaxel and prednisone for patients with metastatic castration-resistant prostate cancer (SYNERGY trial): a phase 3, multicentre, open-label, randomised trial

BACKGROUND

Clusterin is a chaperone protein associated with treatment resistance and upregulated by apoptotic stressors such as chemotherapy. Custirsen is a second-generation antisense oligonucleotide that inhibits clusterin production. The aim of the SYNERGY trial was to investigate the effect of custirsen in combination with docetaxel and prednisone on overall survival in patients with metastatic castration-resistant prostate cancer.

METHODS

SYNERGY was a phase 3, multicentre, open-label, randomised trial set at 134 study centres in 12 countries. Patients were eligible for participation if they had: metastatic castration-resistant prostate cancer and had received no previous chemotherapy; prostate-specific antigen greater than 5 ng/mL; and a Karnofsky performance score of 70% or higher. Patients were randomly assigned 1:1 centrally to either the docetaxel, prednisone, and custirsen combination or docetaxel and prednisone alone. Patients were not masked to treatment allocation. Randomisation was stratified by opioid use for cancer-related pain and radiographic evidence of progression. All patients received docetaxel 75 mg/m² intravenously with 5 mg of prednisone orally twice daily. Patients assigned docetaxel, prednisone, and custirsen received weekly doses of custirsen 640 mg intravenously after three loading doses of 640 mg. The primary endpoint was overall survival analysed in the intention-to-treat population. Patients who received at least one study dose were included in the safety analysis set. This trial is registered with ClinicalTrials.gov, number NCT01188187. The trial is completed and final analyses are reported here.

FINDINGS

Between Dec 10, 2010, and Nov 7, 2012, 1022 patients were enrolled to the trial, of whom 510 were assigned docetaxel, prednisone, and custirsen and 512 were allocated docetaxel and prednisone. No difference in overall survival was recorded between the two groups (median survival 23·4 months [95% CI 20·9-24·8] with docetaxel, prednisone, and custirsen vs 22·0 months [19·5-24·0] with docetaxel and prednisone; hazard ratio [HR] 0·93, 95% CI 0·79-1·10; p=0·415). The most common adverse events of grade 3 or worse in the docetaxel, prednisone and custirsen group (n=501) compared with the docetaxel and prednisone alone group (n=499) were neutropenia (grade 3, 63 [13%] vs 28 [6%]; grade 4, 98 [20%] vs 77 [15%]), febrile neutropenia (grade 3, 52 [10%] vs 31 [6%]; grade 4, four [1%] vs two [<1%]), and fatigue (grade 3, 53 [11%] vs 41 [8%]; grade 4, three [1%] vs one [<1%]). One or more serious adverse events were reported for 214 (43%) of 501 patients treated with docetaxel, prednisone, and custirsen and 181 (36%) of 499 receiving docetaxel and prednisone alone. Adverse events were attributable to 23 (5%) deaths in the docetaxel, prednisone, and custirsen group and 24 (5%) deaths in the docetaxel and prednisone alone group.

INTERPRETATION

Addition of custirsen to first-line docetaxel and prednisone was reasonably well tolerated, but overall survival was not significantly longer for patients with metastatic castration-resistant prostate cancer treated with this combination, compared with patients treated with docetaxel and prednisone alone.

FUNDING

OncoGenex Technologies.

Persistence of senescent prostate cancer cells following prolonged neoadjuvant androgen deprivation therapy

Purpose

Androgen deprivation therapy (ADT) commonly leads to incomplete cell death and the fate of persistent cells involves, in part, a senescent phenotype. Senescence is terminal growth arrest in response to cell stress that is characterized by increased lysosomal-β-galactosidase (GLB1) the origin of senescence associated-β-gal activity (SA-β-gal). In the current study senescence is examined in vivo after ADT use in a neoadjuvant trial.

Methods and materials

Tissue microarrays were generated from prostate cancer specimens (n = 126) from a multicenter neoadjuvant ADT trial. Arrays were subjected to multiplexed immunofluorescent staining for GLB1, Ki67, cleaved caspase 3 (CC3) and E-cadherin. Automated quantitative imaging was performed using Vectra™ and expression correlated with clinicopathologic features.

Results

Tissue was analyzed from 59 patients treated with neoadjuvant ADT and 67 receiving no therapy preoperatively. Median follow-up was 85.3 mo and median ADT treatment was 5 mo. In PC treated with neoadjuvant ADT, GLB1 expression increased in intermediate Gleason score (GS 6–7; p = 0.001), but not high grade (GS 8–10) cancer. Significantly higher levels of GLB1 were seen in tissues undergoing neoadjuvant ADT longer than 5 months compared to untreated tissues (p = 0.002). In contrast, apoptosis significantly increased earlier (1–4 mo) after ADT treatment (p<0.5).

Conclusions

Increased GLB1 after neoadjuvant ADT occurs primarily among more clinically favorable intermediate grade cancers and enrichment of the phenotype occurs in a temporally prolonged fashion. Senescence may explain the persistence of PCa cells after ADT. Given concerns for the detrimental longer term presence of senescent cells, targeting these cells for removal may improve outcomes.

Clusterin as a therapeutic target

INTRODUCTION

Clusterin (CLU) is a stress-activated, ATP-independent molecular chaperone, normally secreted from cells, that is up-regulated in Alzheimer disease and in many cancers. It plays important roles in protein homeostasis/proteostasis, inhibition of cell death pathways, and modulation of pro-survival signalling and transcriptional networks. Changes in the CLU gene locus are highly associated with Alzheimer disease, and many therapy-resistant cancers over-express CLU. The extensive post-translational processing and heterogeneous oligomerization of CLU have so far prevented any definitive structure determination. This in turn has meant that targeting CLU with small molecule inhibitors is challenging. Therefore, inhibiting CLU at the gene-expression level using siRNA or antisense is a valid approach to inhibit its function. Areas covered: This article reviews recent advances regarding the role of CLU in proteostasis, cellular trafficking, human diseases, and signalling pathways involved in oncogenesis. It addresses the rationale for CLU as a therapeutic target in cancer, and the current status of pre-clinical and clinical studies using CLU antisense inhibitor OGX011. Expert opinion: Discusses challenges facing the therapeutic targeting of CLU including rapid changes in the treatment landscape for prostate cancer with multiple new FDA approved drugs, selection of windows of intervention, and potential side effects when silencing CLU expression.

The role of chemotherapy and new targeted agents in the management of primary prostate cancer

While early treatment of primary prostate cancer is very effective, the incidence of primary prostate cancer continues to rise and therefore the detection of men with high-risk non-metastatic prostate cancer and their subsequent management is becoming increasingly important. There continues to be no molecularly-targeted or chemotherapeutic options with proven, statistically significant survival benefit in this setting. However, there are indications that further risk stratification using molecular features could potentially help distinguish indolent from aggressive prostate cancer, ultimately providing biological markers that could guide a more personalised approach to therapy selection.

RNA-targeted therapeutics in cancer clinical trials: Current status and future directions

Recent advances in RNA delivery and target selection provide unprecedented opportunities for cancer treatment, especially for cancers that are particularly hard to treat with existing drugs. Small interfering RNAs, microRNAs, and antisense oligonucleotides are the most widely used strategies for silencing gene expression. In this review, we summarize how these approaches were used to develop drugs targeting RNA in human cells. Then, we review the current state of clinical trials of these agents for different types of cancer and outcomes from published data. Finally, we discuss lessons learned from completed studies and future directions for this class of drugs.

Disposition and Pharmacokinetics of a GalNAc3-Conjugated Antisense Oligonucleotide Targeting Human Lipoprotein (a) in Monkeys

Triantennary N-acetyl galactosamine (GalNAc₃)-conjugated antisense oligonucleotides (ASOs) have greatly improved potency due to receptor-mediated uptake into hepatocyte. The disposition and pharmacokinetics of ISIS 681257, a GalNAc₃-conjugated ASO, were studied in monkeys. Following subcutaneous (SC) injection, ISIS 681257 was rapidly absorbed into the systemic circulation, with peak plasma levels observed within hours after dosing. After reaching C_max, plasma concentrations rapidly declined in a multiexponential manner and were characterized by a dominant initial rapid distribution phase in which drug transferred to tissues from circulation, followed by a much slower terminal elimination phase (half-life of 4 weeks). Intact ISIS 681257 is the major full-length oligonucleotide species in plasma (≥70%). In tissues, the conjugated-GalNAc sugar moiety was rapidly metabolized, leaving the fully unconjugated form as the only full-length oligonucleotide detected at 48 h after dosing. Unconjugated ISIS 681257 cleared slowly from tissues with a half-life of 4 weeks. ISIS 681257 was highly bound to plasma proteins (>97% bound), which limited its urinary excretion. Disposition of ISIS 681257 in plasma and liver appeared nonlinear over the 1-40 mg/kg dose range studied. The plasma and liver tissue concentration data were well described by a population based mixed-effects modeling approach with Michaelis-Menten uptake from plasma to liver. Safety data from the study and the good exposure, as well as the extended half-life of the unconjugated ASO in the liver, support further development and less frequent dosing in Phase I clinical study.

Novel Targeted Therapy for Precursor B Cell Acute Lymphoblastic Leukemia: anti-CD22 Antibody-MXD3 Antisense Oligonucleotide Conjugate

The exponential rise in molecular and genomic data has generated a vast array of therapeutic targets. Oligonucleotide-based technologies to down regulate these molecular targets have promising therapeutic efficacy. However, there is relatively limited success in translating this into effective in vivo cancer therapeutics. The primary challenge is the lack of effective cancer cell-targeted delivery methods, particularly for a systemic disease such as leukemia. We developed a novel leukemia-targeting compound composed of a monoclonal antibody directly conjugated to an antisense oligonucleotide (ASO). Our compound uses an ASO that specifically targets the transcription factor MAX dimerization protein 3 (MXD3), which was previously identified to be critical for precursor B cell (preB) acute lymphoblastic leukemia (ALL) cell survival. The MXD3 ASO was conjugated to an anti-CD22 antibody (αCD22 Ab) that specifically targets most preB ALL. We demonstrated that the αCD22 Ab-ASO conjugate treatment showed MXD3 protein knockdown and leukemia cell apoptosis in vitro. We also demonstrated that the conjugate treatment showed cytotoxicity in normal B cells, but not in other hematopoietic cells, including hematopoietic stem cells. Furthermore, the conjugate treatment at the lowest dose tested (0.2mg/kg Ab for 6 doses - twice a week for 3 weeks) more than doubled the mouse survival time in both Reh (median survival time 20.5 vs. 42.5 days, p<0.001) and primary preB ALL (median survival time 29.3 vs. 63 days, p<0.001) xenograft models. Our conjugate that uses αCD22 Ab to target the novel molecule MXD3, which is highly expressed in preB ALL cells, appears to be a promising novel therapeutic approach.

Nucleic acid polymers: Broad spectrum antiviral activity, antiviral mechanisms and optimization for the treatment of hepatitis B and hepatitis D infection

Antiviral polymers are a well-studied class of broad spectrum viral attachment/entry inhibitors whose activity increases with polymer length and with increased amphipathic (hydrophobic) character. The newest members of this class of compounds are nucleic acid polymers whose activity is derived from the sequence independent properties of phosphorothioated oligonucleotides as amphipathic polymers. Although the antiviral mechanisms and broad spectrum antiviral activity of nucleic acid polymers mirror the functionality of other members of this class, they exert in addition a unique post entry activity in hepatitis B infection which inhibits the release of HBsAg from infected hepatocytes. This review provides a general overview of the antiviral polymer class with a focus on nucleic acid polymers and their development as therapeutic agents for the treatment of hepatitis B/hepatitis D. This article forms part of a symposium in Antiviral Research on ''An unfinished story: from the discovery of the Australia antigen to the development of new curative therapies for hepatitis B.''.

Clusterin knockdown sensitizes prostate cancer cells to taxane by modulating mitosis

Clusterin (CLU) is a stress‐activated molecular chaperone that confers treatment resistance to taxanes when highly expressed. While CLU inhibition potentiates activity of taxanes and other anti‐cancer therapies in preclinical models, progression to treatment‐resistant disease still occurs implicating additional compensatory survival mechanisms. Taxanes are believed to selectively target cells in mitosis, a complex mechanism controlled in part by balancing antagonistic roles of Cdc25C and Wee1 in mitosis progression. Our data indicate that CLU silencing induces a constitutive activation of Cdc25C, which delays mitotic exit and hence sensitizes cancer cells to mitotic‐targeting agents such as taxanes. Unchecked Cdc25C activation leads to mitotic catastrophe and cell death unless cells up‐regulate protective mechanisms mediated through the cell cycle regulators Wee1 and Cdk1. In this study, we show that CLU silencing induces a constitutive activation of Cdc25C via the phosphatase PP2A leading to relief of negative feedback inhibition and activation of Wee1‐Cdk1 to promote survival and limit therapeutic efficacy. Simultaneous inhibition of CLU‐regulated cell cycle effector Wee1 may improve synergistic responses of biologically rational combinatorial regimens using taxanes and CLU inhibitors.

Integrated Safety Assessment of 2'-O-Methoxyethyl Chimeric Antisense Oligonucleotides in NonHuman Primates and Healthy Human Volunteers

The common chemical and biological properties of antisense oligonucleotides provide the opportunity to identify and characterize chemical class effects across species. The chemical class that has proven to be the most versatile and best characterized is the 2′-O-methoxyethyl chimeric antisense oligonucleotides. In this report we present an integrated safety assessment of data obtained from controlled dose-ranging studies in nonhuman primates (macaques) and healthy human volunteers for 12 unique 2′-O-methoxyethyl chimeric antisense oligonucleotides. Safety was assessed by the incidence of safety signals in standardized laboratory tests for kidney and liver function, hematology, and complement activation; as well as by the mean test results as a function of dose level over time. At high doses a number of toxicities were observed in nonhuman primates. However, no class safety effects were identified in healthy human volunteers from this integrated data analysis. Effects on complement in nonhuman primates were not observed in humans. Nonhuman primates predicted safe doses in humans, but over predicted risk of complement activation and effects on platelets. Although limited to a single chemical class, comparisons from this analysis are considered valid and accurate based on the carefully controlled setting for the specified study populations and within the total exposures studied.

Modulation of tumor eIF4E by antisense inhibition: A phase I/II translational clinical trial of ISIS 183750-an antisense oligonucleotide against eIF4E-in combination with irinotecan in solid tumors and irinotecan-refractory colorectal cancer

The eukaryotic translation initiation factor 4E (eIF4E) is a potent oncogene that is found to be dysregulated in 30% of human cancer, including colorectal carcinogenesis (CRC). ISIS 183750 is a second-generation antisense oligonucleotide (ASO) designed to inhibit the production of the eIF4E protein. In preclinical studies we found that EIF4e ASOs reduced expression of EIF4e mRNA and inhibited proliferation of colorectal carcinoma cells. An additive antiproliferative effect was observed in combination with irinotecan. We then performed a clinical trial evaluating this combination in patients with refractory cancer. No dose-limiting toxicities were seen but based on pharmacokinetic data and tolerability the dose of irinotecan was reduced to 160 mg/m(2) biweekly. Efficacy was evaluated in 15 patients with irinotecan-refractory colorectal cancer. The median time of disease control was 22.1 weeks. After ISIS 183750 treatment, peripheral blood levels of eIF4E mRNA were decreased in 13 of 19 patients. Matched pre- and posttreatment tumor biopsies showed decreased eIF4E mRNA levels in five of nine patients. In tumor tissue, the intracellular and stromal presence of ISIS 183750 was detected by IHC in all biopsied patients. Although there were no objective responses stable disease was seen in seven of 15 (47%) patients who were progressing before study entry, six of whom were stable at the time of the week 16 CT scan. We were also able to confirm through mandatory pre- and posttherapy tumor biopsies penetration of the ASO into the site of metastasis.

Safety and Efficacy of Nucleic Acid Polymers in Monotherapy and Combined with Immunotherapy in Treatment-Naive Bangladeshi Patients with HBeAg+ Chronic Hepatitis B Infection

Previous in vivo studies have suggested that nucleic acid polymers (NAPs) may reduce circulating levels of HBsAg in the blood by blocking its release from infected hepatocytes and that this effect may have clinical benefit. NAP treatment, was evaluated in two clinical studies in patients with HBeAg positive chronic HBV infection. The REP 101 study examined REP 2055 monotherapy in 8 patients and the REP 102 study examined REP 2139-Ca, in monotherapy in 12 patients, 9 of which transitioned to short term combined treatment with pegylated interferon alpha 2a or thymosin alpha 1. In both studies NAP monotherapy was accompanied by 2–7 log reductions of serum HBsAg, 3–9 log reductions in serum HBV DNA and the appearance of serum anti-HBsAg antibodies (10–1712 mIU / ml). Eight of the 9 patients transitioning to combined treatment with immunotherapy (pegylated interferon or thymosin alpha 1) in the REP 102 study experienced HBsAg loss and all 9 patients experienced substantial increases in serum anti-HBsAg antibody titers before withdrawal of therapy. For 52 weeks after removal of REP 2055 therapy, rebound of serum viremia (HBV DNA > 1000 copies / ml, HBsAg > 1IU / ml) was not observed in 3 / 8 patients. Suppression of serum virema was further maintained for 290 and 231 weeks in 2 of these patients. After withdrawal of all therapy in the 9 patients that transitioned to combination therapy in the REP 102 study, 8 patients achieved HBV DNA < 116 copies / ml after treatment withdrawal. Viral rebound occurred over a period of 12 to 123 weeks in 7 patients but was still absent in two patients at 135 and 137 weeks of follow-up. Administration tolerability issues observed with REP 2055 were rare with REP 2139-Ca but REP 2139-Ca therapy was accompanied by hair loss, dysphagia and dysgeusia which were considered related to heavy metal exposure endemic at the trial site. These preliminary studies suggest that NAP can elicit important antiviral responses during treatment which may improve the effect of immunotherapy. NAPs may be a potentially useful component of future combination therapies for the treatment of chronic hepatitis B.

Trial Registration: ClinicalTrials.gov NCT02646163 and NCT02646189

Effects of Repeated Complement Activation Associated with Chronic Treatment of Cynomolgus Monkeys with 2'-O-Methoxyethyl Modified Antisense Oligonucleotide

The effects of repeated complement activation in cynomolgus monkeys after chronic antisense oligonucleotide (ASO) treatment were evaluated by using ISIS 104838, a representative 2'-O-methoxyethyl (2'-MOE) modified ASO. The treatment was up to 9 months with a total weekly dose of 30 mg/kg, given either as daily [4.3 mg/kg/day, subcutaneous (s.c.) injection] or once weekly [30 mg/kg, either as s.c. injection or 30-min intravenous (i.v.) infusion]. Acute elevations of complement split products (Bb and C3a) and a transient decrease in C3 occurred after the first dose and were drug plasma concentration dependent. However, with repeated complement activation after chronic ASO treatment, there were progressive increases in basal (predose) levels of Bb and C3a, and a sustained C3 reduction in all treated groups. There was also a progressive increase in C3d-bound circulating immune complex (CIC) that was considered secondary to the C3 depletion. Evidence of vascular inflammation was observed, mostly in the liver, kidney, and heart, and correlated with severe C3 depletion and increases in plasma IgG and IgM. Vascular inflammation was accompanied by increased C3 and IgM immunereactivity in the affected vasculatures and endothelial activation markers in serum. In summary, repeated complement activations in monkeys lead to a sustained decrease in circulating C3 over time. The concomitantly increased inflammatory signals and decreased CIC clearance due to impairment of complement function may lead to vascular inflammation after chronic ASO treatment in monkeys. However, based on the known sensitivity of monkeys to ASO-induced complement activation, these findings have limited relevance to humans.

Disposition and Pharmacology of a GalNAc3-conjugated ASO Targeting Human Lipoprotein (a) in Mice

Triantennary N-acetyl galactosamine (GalNAc₃)-conjugated antisense oligonucleotides (ASOs) have greatly improved potency via receptor-mediated uptake. In the present study, the in vivo pharmacology of a 2′-O-(2-methoxyethyl)-modified ASO conjugated with GalNAc₃ (ISIS 681257) together with its unmodified congener (ISIS 494372) targeting human apolipoprotein (a) (apo(a)), were studied in human LPA transgenic mice. Further, the disposition kinetics of ISIS 681257 was studied in CD-1 mice. ISIS 681257 demonstrated over 20-fold improvement in potency over ISIS 494372 as measured by liver apo(a) mRNA and plasma apo(a) protein levels. Following subcutaneous (SC) dosing, ISIS 681257 cleared rapidly from plasma and distributed to tissues. Intact ISIS 681257 was the major full-length oligonucleotide species in plasma. In tissues, however, GalNAc sugar moiety was rapidly metabolized and unconjugated ISIS 681257 accounted > 97% of the total exposure, which was then cleared slowly from tissues with a half-life of 7–8 days, similar to the half-life in plasma. ISIS 681257 is highly bound to plasma proteins (> 94% bound), which limited its urinary excretion. This study confirmed dose-dependent exposure to the parent drug ISIS 681257 in plasma and rapid conversion to unconjugated ASO in tissues. Safety data and the extended half-life support its further development and weekly dosing in phase 1 clinical studies.

Considerations for the Characterization and Interpretation of Results Related to Alternative Complement Activation in Monkeys Associated with Oligonucleotide-Based Therapeutics

This article provides an overview of the discussions held by the Immunomodulatory Subcommittee of the Oligonucleotide Safety Working Group on complement activation induced by oligonucleotides, most notably the phosphorothioate-containing oligonucleotides. Alternative complement pathway activation in monkeys is a common effect of single-stranded phosphorothioate backbone oligonucleotides in toxicology studies. This article discusses the mechanism for activation, general investigational strategy, and the impact of various chemical modifications. The goal is to provide the best practice approach to characterizing this effect, understanding the implication of the species specificity, and the interpretation of clinical relevance.

Downregulation of clusterin mediates sensitivity to protein kinase inhibitors in breast cancer cells

The efficacy of protein kinase inhibitors (PKIs) has been shown in clinical assays for cancer, but as isolated agents, they only have a modest effect. One of the most important characteristics of mitogen-activated PKIs is their ability to decrease the apoptotic threshold of cancer cells, sensitizing them to the action of other antiapoptotic agents. The secretory clusterin protein is an inhibitor of apoptosis with a cytoprotective function. We describe the use of clusterin-specific antisense oligonucleotides and siRNA to sensitize breast carcinoma cells to several PKIs. MCF-7 and MDA-MB-231 cells were treated with antisense oligonucleotide or siRNA to clusterin and the following PKIs: H-89, chelerythrine and genistein. The three inhibitors used in this study upregulated clusterin expression and treatments that included antisense oligonucleotide or siRNA to clusterin reduced the number of viable cells more effectively than did treatment with the drugs alone. Therefore, treatment with such combinations may benefit patients with breast cancer.

A phase I dose-escalation study of apatorsen (OGX-427), an antisense inhibitor targeting heat shock protein 27 (Hsp27), in patients with castration-resistant prostate cancer and other advanced cancers

BACKGROUND

Heat shock protein 27 (Hsp27) is a chaperone protein that regulates cell survival via androgen receptor and other signaling pathways, thereby mediating cancer progression. Apatorsen (OGX-427) is a 2'-methoxyethyl-modified antisense oligonucleotide that inhibits Hsp27 expression. This study evaluated the safety profile and recommended phase II dosing of apatorsen in patients with advanced cancer.

PATIENTS AND METHODS

Patients with castration-resistant prostate (CRPC), breast, ovary, lung, or bladder cancer were enrolled to this phase I dose-escalation study. Apatorsen was administered i.v. weekly in 21-day cycles following 3 loading doses and over 5 dose levels (200-1000 mg). Apatorsen plasma concentrations, circulating tumor cells (CTCs) and CTC Hsp27 expression, and serum Hsp27 levels were evaluated.

RESULTS

Forty-two patients were accrued, of which 52% had CRPC. Patients were heavily pretreated, with 57% having had ≥3 prior chemotherapy regimens. During the loading dose/cycle 1 and overall study period, 93% and 100% of patients (N = 42) experienced treatment-related adverse events, respectively; most were grade 1-2 and included chills, pruritus, flushing, prolonged aPTT, lymphopenia, and anemia. One patient experienced a dose-limiting toxicity at the 600 mg dose level (intracranial hemorrhage in a previously undiagnosed brain metastasis). A maximum tolerated dose was not defined. Apatorsen Cmax increased proportionally with dose. Decreases in tumor markers and declines in CTCs were observed, with a prostate-specific antigen decline >%50% occurring in 10% of patients with CRPC; 29/39 assessable patients (74%) had reductions from ≥5 CTC/7.5 ml at baseline to <5 CTC/7.5 ml post-treatment. Twelve patients had stable measurable disease as best response.

CONCLUSIONS

Apatorsen was tolerated at the highest dose evaluated (1000 mg). Single-agent activity was suggested by changes in tumor markers, CTC, and stable measurable disease. Phase II studies evaluating apatorsen are underway.

CLINICALTRIALSGOV ID

NCT00487786.

The Bromodomain Inhibitor JQ1 and the Histone Deacetylase Inhibitor Panobinostat Synergistically Reduce N-Myc Expression and Induce Anticancer Effects

PURPOSE

Patients with neuroblastoma associated with MYCN oncogene amplification experience a very poor prognosis. BET bromodomain inhibitors are among the most promising novel anticancer agents as they block BRD3 and BRD4 from activating oncogene transcription. However, treatment with BET bromodomain inhibitors alone does not result in cancer remission in many murine models.

EXPERIMENTAL DESIGN

MYCN-amplified neuroblastoma cells were treated with vehicle control, the BET bromodomain inhibitor JQ1, the histone deacetylase inhibitor panobinostat, or the combination of JQ1 and panobinostat. Genes modulated by JQ1, panobinostat, or the combination therapy were identified by Affymetrix microarray, and cell proliferation and apoptosis were examined by Alamar blue assays and flow cytometry analysis. Modulation of LIN28B promoter activity by BRD3 and BRD4 was examined by chromatin immunoprecipitation and luciferase assays. In addition, neuroblastoma-bearing mice were treated with vehicle control, JQ1, and/or panobinostat.

RESULTS

LIN28B was one of the top genes synergistically reduced by JQ1 and panobinostat. BRD3 and BRD4 directly bound to the LIN28B gene promoter and activated LIN28B gene transcription, and knocking down LIN28B reduced the expression of N-Myc protein, but not N-Myc mRNA. JQ1 and panobinostat synergistically reduced LIN28B gene and N-Myc protein expression, and synergistically induced growth inhibition and apoptosis in neuroblastoma cells, but not normal nonmalignant cells in vitro In neuroblastoma-bearing mice, JQ1 and panobinostat synergistically and considerably reduced N-Myc protein expression in tumor tissues and blocked tumor progression.

CONCLUSIONS

Our findings have identified a novel strategy to reduce the N-Myc oncoprotein expression and a novel therapeutic approach for the treatment of aggressive neuroblastoma. Clin Cancer Res; 22(10); 2534-44. ©2016 AACR.

Oligonucleotide-Based Drug Development: Considerations for Clinical Pharmacology and Immunogenicity

The field of oligonucleotide (OGN)-based therapeutics has been growing dramatically in the past decade, providing innovative platforms to develop agents for the treatment of a wide variety of clinical conditions. OGN agents have unique physicochemical properties and pharmacokinetic/pharmacodynamic characteristics. This review considers findings from the literature and information on new molecular entities submitted to the US Food and Drug Administration as OGN-based therapeutics. In addition, the article discusses several challenging issues from the perspective of clinical pharmacology, emphasizing the potential of immunogenicity, the effect of renal impairment on OGN exposure, drug-drug interactions, and the utility of pharmacokinetic/pharmacodynamic modeling. The field of OGN-based therapeutics is in evolution and will benefit from further studies as well as clinical experience to formulate guidelines and promote the development of this class of agents.

HMGB1 induction of clusterin creates a chemoresistant niche in human prostate tumor cells

Development of chemoresistance, especially to docetaxel (DTX), is the primary barrier to the cure of castration-resistant prostate cancer but its mechanism is obscure. Here, we report a seminal crosstalk between dying and residual live tumor cells during treatment with DTX that can result in outgrowth of a chemoresistant population. Survival was due to the induction of secretory/cytoplasmic clusterin (sCLU), which is a potent anti-apoptotic protein known to bind and sequester Bax from mitochondria, to prevent caspase 3 activation. sCLU induction in live cells depended on HMGB1 release from dying cells. Supernatants from DTX-treated DU145 tumor cells, which were shown to contain HMGB1, effectively induced sCLU from newly-plated DU145 tumor cells and protected them from DTX toxicity. Addition of anti-HMBG1 to the supernatant or pretreatment of newly-plated DU145 tumor cells with anti-TLR4 or anti-RAGE markedly abrogated sCLU induction and protective effect of the supernatant. Mechanistically, HMGB1 activated NFκB to promote sCLU gene expression and prevented the translocation of activated Bax to mitochondria to block cell death. Importantly, multiple currently-used chemotherapeutic drugs could release HMGB1 from tumor cells. These results suggest that acquisition of chemoresistance may involve the HMGB1/TLR4-RAGE/sCLU pathway triggered by dying cells to provide survival advantage to remnant live tumor cells.

The role of antisense oligonucleotide therapy in patients with familial hypercholesterolemia: risks, benefits, and management recommendations

Antisense oligonucleotide therapy is a promising approach for the treatment of a broad variety of medical conditions. It functions at the cellular level by interfering with RNA function, often leading to degradation of specifically targeted abnormal gene products implicated in the disease process. Mipomersen is a novel antisense oligonucleotide directed at apolipoprotein (apoB)-100, the primary apolipoprotein associated with low-density lipoprotein cholesterol (LDL-C), which has recently been approved for the treatment of familial hypercholesterolemia. A number of clinical studies have demonstrated its efficacy in lowering LDL-C and apoB levels in patients with elevated LDL-C despite maximal medical therapy using conventional lipid-lowering agents. This review outlines the risks and benefits of therapy and provides recommendations on the use of mipomersen.