Treatment with Volanesorsen, a 2'-O-Methoxyethyl-Modified Antisense Oligonucleotide Targeting APOC3 mRNA, Does Not Affect the QTc Interval in Healthy Volunteers.

The aim of this study was to assess the effect of volanesorsen on the corrected QT (QTc) interval. This thorough QT study enrolled 52 healthy male and female subjects who were randomized at a single site in a four-way crossover study. Subjects were randomly assigned to 1 of 12 treatment sequences and crossed over into four treatment periods over the course of which each subject was to receive a single therapeutic dose of volanesorsen as a 300 mg subcutaneous (SC) injection, a single supratherapeutic dose of volanesorsen as 300 mg intravenous (IV) infusion, a single oral (PO) dose of moxifloxacin (positive control), and placebo dose. The study demonstrated that volanesorsen 300 mg SC and 300 mg IV did not have a clinically relevant effect on ΔΔQTcF exceeding 10 ms. The largest mean effect at any postdose time point was 3.0 ms (90% confidence interval [CI]: 0.8-5.2) after SC dosing and 1.8 ms (90% CI -0.4 to 4.0) after IV dosing. Volanesorsen, at the studied therapeutic and supratherapeutic doses, does not have a clinically meaningful effect on the QTc.

Pharmacological treatment options for severe hypertriglyceridemia and familial chylomicronemia syndrome.

INTRODUCTION: A spectrum of disorders, ranging from rare severe cases of homozygous null lipoprotein lipase deficiency (LPLD)-familial chylomicronemia syndrome (FCS) to heterozygous missense LPLD or polygenic causes, result in hypertriglyceridemia and pancreatitis. The effects of mutations are exacerbated by environmental factors such as diet, pregnancy, and insulin resistance. Areas covered: In this review, authors discuss chronic treatment of FCS by ultra-low fat diets allied with the use of fibrates, omega-3 fatty acids, niacin, statins, and insulin-sensitizing therapies depending on the extent of residual lipoprotein lipase (LPL) activity; novel therapies in development target triglyceride (TG)-rich lipoprotein particle clearance. Previously, a gene therapy approach to LPL-alipogene tiparvovec showed that direct targeting of LPL function reduced pancreatitis events. An antisense oligonucleotide to apolipoprotein-C3, volanesorsen has been shown to decrease TGs by 70-80% and possibly to reduce rates of pancreatitis admissions. Studies are underway to validate its long-term efficacy and safety. Other approaches investigating the role of LPL modulating proteins such as angiopoietin-like petide-3 (ANGPTL3) are under consideration. Expert opinion: Current therapeutic options are not sufficient for management of many cases of FCS. The availability of antisense anti-apoC3 therapies and, in the future, ANGPTL3 therapies may remedy this.

The role of antisense oligonucleotide therapy against apolipoprotein-CIII in hypertriglyceridemia.

Increased triglyceride levels (higher than ∼1000 mg/dL) are associated with an increased risk for pancreatitis. Apolipoprotein-CIII (apo-CIII) plays a key role in the metabolism of triglycerides and triglyceride-rich lipoproteins. While loss of function mutations in the gene encoding apo-CIII (APOC3) are associated with low triglyceride levels and a decreased risk for cardiovascular disease (CVD), overexpression of APOC3 is associated with hypertriglyceridemia. Although many drugs such as fibrates, statins and omega-3 fatty acids modestly decrease triglyceride levels (and apo-CIII concentrations), there are many patients who still have severe hypertriglyceridemia and are at risk for pancreatitis and potentially CVD. The antisense oligonucleotide (ASO) against APOC3 mRNA volanesorsen (previously called ISIS 304801, ISIS-ApoCIIIRx and IONIS-ApoCIIIRx) robustly decreases both, apo-CIII production and triglyceride concentrations and is being currently evaluated in phase 3 trials. In this narrative review we present the currently available clinical evidence on the efficacy and safety of volanesorsen for the treatment of hypertriglyceridemia.

Nusinersen: antisense oligonucleotide to increase SMN protein production in spinal muscular atrophy.

Patients with spinal muscular atrophy (SMA) have an autosomal recessive disease that limits their ability to produce survival motor neuron (SMN) protein in the CNS resulting in progressive wasting of voluntary muscles. Detailed studies over several years have demonstrated that phosphorothioate and 2'-O-methoxyethyl- modified antisense oligonucleotides (ASOs) targeting the ISS-N1 site increase SMN2 exon 7 inclusion, thus increasing levels of SMN protein in a dose- and time-dependent manner in liver, kidney and skeletal muscle, and CNS tissues only when administered intrathecally. On a dose basis, nusinersen was found to be the most potent ASO for SMN2 splicing correction in the CNS of adult mice. After nusinersen was found to increase levels of SMN protein in the CNS of mice and subhuman primates without causing significant adverse events, it was advanced into clinical studies in patients with SMA. These trials in SMA patients have demonstrated significant improvements in various measures of motor function and in progression to movement developments not normally seen in SMA patients. In addition, there have been significant extensions in life expectancy. These findings led to the U.S. and European approval of nusinersen for use in SMA patients of all ages.

Scientific and Regulatory Policy Committee Points-to-consider Paper*: Drug-induced Vascular Injury Associated with Nonsmall Molecule Therapeutics in Preclinical Development: Part 2. Antisense Oligonucleotides.

Drug-induced vascular injury (DIVI) is a recurrent challenge in the development of novel pharmaceutical agents. In recent years, DIVI has been occasionally observed in nonhuman primates given RNA-targeting therapeutics such as antisense oligonucleotide therapies (ASOs) during chronic toxicity studies. While DIVI in laboratory animal species has been well characterized for vasoactive small molecules, and immune-mediated responses against large molecule biotherapeutics have been well described, there is little published information regarding DIVI induced by ASOs to date. Preclinical DIVI findings in monkeys have caused considerable delays in development of promising new ASO therapies, because of the uncertainty about whether DIVI in preclinical studies is predictive of effects in humans, and the lack of robust biomarkers of DIVI. This review of DIVI discusses clinical and microscopic features of vasculitis in monkeys, their pathogenic mechanisms, and points to consider for the toxicologist and pathologist when confronted with ASO-related DIVI. Relevant examples of regulatory feedback are included to provide insight into risk assessment of ASO therapies.

Species-specific inflammatory responses as a primary component for the development of glomerular lesions in mice and monkeys following chronic administration of a second-generation antisense oligonucleotide.

Chronic administration of drisapersen, a 2'-OMe phosphorothioate antisense oligonucleotide (AON) to mice and monkeys resulted in renal tubular accumulation, with secondary tubular degeneration. Glomerulopathy occurred in both species with species-specific characteristics. Glomerular lesions in mice were characterized by progressive hyaline matrix accumulation, accompanied by the presence of renal amyloid and with subsequent papillary necrosis. Early changes involved glomerular endothelial hypertrophy and degeneration, but the chronic glomerular amyloid and hyaline alterations in mice appeared to be species specific. An immune-mediated mechanism for the glomerular lesions in mice was supported by early inflammatory changes including increased expression of inflammatory cytokines and other immunomodulatory genes within the renal cortex, increased stimulation of CD68 protein, and systemic elevation of monocyte chemotactic protein 1. In contrast, kidneys from monkeys given drisapersen chronically showed less severe glomerular changes characterized by increased mesangial and inflammatory cells, endothelial cell hypertrophy, and subepithelial and membranous electron-dense deposits, with ultrastructural and immunohistochemical characteristics of complement and complement-related fragments. Lesions in monkeys resembled typical features of C3 glomerulopathy, a condition described in man and experimental animals to be linked to dysregulation of the alternative complement pathway. Thus, inflammatory/immune mechanisms appear critical to glomerular injury with species-specific sensitivities for mouse and monkey. The lower observed proinflammatory activity in humans as compared to mice and monkeys may reflect a lower risk of glomerular injury in patients receiving AON therapy.

PRO-051, an antisense oligonucleotide for the potential treatment of Duchenne muscular dystrophy.

PRO-051 (GSK-2402968), being developed by GlaxoSmithKline plc, under license from Leiden University Medical Center and Prosensa Therapeutics BV, is a 2'-O-methyl phosphorothioate antisense oligonucleotide for the potential treatment of Duchenne muscular dystrophy (DMD). The PRO-051 oligonucleotide sequence induces skipping of exon 51 of the dystrophin gene by binding to a sequence within the dystrophin pre-mRNA and masking the exon inclusion signals that are used for splicing. Removal of exon 51 from an exon 45 to 50, 47 to 50, 48 to 50, 49 to 50, 50, 52 or 52 to 63 deleted transcript allows restoration of the open reading frame and synthesis of an internally truncated, semi-functional dystrophin protein. By targeting exon 51, approximately 13% of patients with DMD could be treated, the largest proportion of patients that could benefit from targeting a single dystrophin exon. A proof-of-concept clinical trial of PRO-051 in patients with DMD demonstrated that a single intramuscular administration of PRO-051 induced exon skipping within muscle fibers adjacent to the injection site, while biopsies revealed dystrophin expression in treated but not control muscle fibers. At the time of publication, a phase I/IIa trial to evaluate subcutaneous delivery of PRO-051 had been completed, although full results were yet to be published.

Trabedersen, a TGFbeta2-specific antisense oligonucleotide for the treatment of malignant gliomas and other tumors overexpressing TGFbeta2.

Trabedersen (AP-12009), which is being developed by Antisense Pharma GmbH, is a synthetic antisense oligodeoxynucleotide designed to block the production of TGFbeta2, a secreted protein that can exert protumor effects. Trabedersen is indicated for the treatment of malignant brain tumors and other solid tumors overexpressing TGFbeta2, such as those of the skin, pancreas and colon. Preclinical studies demonstrated that trabedersen reduced the secretion of TGFbeta2 in cultured tumor cells and exhibited antitumor activity ex vivo. It was also demonstrated that chronic intracerebral or intravascular administration of trabedersen did not cause life-threatening side effects in animals. This observation was confirmed in early clinical trials in patients with advanced cancer. In a phase IIb trial, improved survival was observed in patients with brain tumors who were intratumorally administered trabedersen, compared with patients receiving standard chemotherapy. However, this observation requires validation by an ongoing large-scale, phase III, randomized, controlled trial. Meanwhile, continued research on trabedersen should help to determine the roles of TGFbeta2 in cancer and also further the development of antisense technology.

AEG-35156, an antisense oligonucleotide against X-linked inhibitor of apoptosis for the potential treatment of cancer.

Aegera, under license from Idera Pharmaceuticals, is developing AEG-35156, a 19-mer phosphorothioate antisense oligonucleotide targeting the caspase inhibitor X-linked inhibitor of apoptosis protein (XIAP) messenger RNA, for the potential treatment of cancer. Several clinical trials are ongoing and include: two phase I monotherapy clinical trials for the potential treatment of cancer and in patients with solid tumors; a phase I combination clinical trial of AEG-35156 with docetaxel in locally advanced, metastatic, or recurrent solid tumors; four phase I/II combination clinical trials for the potential treatment of pancreatic cancer, advanced breast cancer, advanced NSCLC, and acute myeloid leukemia. Mild to moderate adverse effects were observed in early phase clinical trials. Aegera plans to initiate randomized phase III trials if tolerable side effects and evidence of activity are demonstrated in phase I/II clinical trials.

Technology evaluation: AVI-4126, AVI BioPharma.

AVI BioPharma is developing AVI-4126, an antisense oligonucleotide targeted to c-myc mRNA for the potential treatment of restenosis, cancer and polycystic kidney disease. AVI-4126 is currently undergoing phase II clinical trials.

[Proapoptotic therapy with oblimersen (bcl-2 antisense oligonucleotide)--review of preclinical and clinical results]. / Proapoptotische Therapie mit Oblimersen (bcl-2-Antisense-Oligonukleotid)--Ubersicht über präklinische und klinische Daten.

The regulation of apoptosis is an important potential target for anticancer therapy. The mitochondrial Bcl-2 protein inhibits apoptosis and is therefore an important mediator of resistance to treatment with traditional cytotoxic chemotherapy, radiotherapy and monoclonal antibody therapy. Oblimersen (Genasense, Aventis Pharmaceuticals / Genta Inc) is a 18mer antisense-oligonucleotide (ASO), which specifically binds to the first 6 codons of the human bcl-2 mRNA, resulting in degradation and destruction of the mRNA by RNAse H. Subsequently there is a significant decrease of bcl-2 translation. A growing number of preclinical and clinical studies suggests that the combination of cytotoxic therapy with Oblimersen results in synergistic anticancer efficacy in many hematologic and solid tumors. Due to its low toxicity profile, oblimersen is an ideal combination partner with conventional chemotherapy. Three randomized phase-III trials (malignant melanoma, chronic lymphocytic leukemia, multiple myeloma) have recently finished recruitment. The results of these studies will be available by the end of 2003. Based on preclinical data, a lot of nonrandomized phase-II studies on several different tumor types like AML, CML, NHL, prostate cancer and breast cancer are underway. The manipulation of proapoptotic and antiapoptotic factors in favor of proapoptotic factors by inhibition of the bcl-2 protein translation in order to enhance the efficacy of anticancer treatments represents a promising new treatment concept in oncology.

Efficiency of antisense oligonucleotide drug discovery.

The costs for discovering and developing new drugs continue to escalate, with current estimates that the average cost is more than $800 million for each new drug brought to the market. Pharmaceutical companies are under enormous pressure to increase their efficiency for bringing new drugs to the market by third-party payers, shareholders, and their patients, and at the same time regulators are placing increased demands on the industry. To be successful in the future, pharmaceutical companies must change how they discover and develop new drugs. So far, new technologies have done little to increase overall efficiency of the industry and have added additional costs. Platform technologies such as monoclonal antibodies and antisense oligonucleotides have the potential of reducing costs for discovery of new drugs, in that many of the steps required for traditional small molecules can be skipped or streamlined. Additionally the success of identifying a drug candidate is much higher with platform technologies compared to small molecule drugs. This review will highlight some of the efficiencies of antisense oligonucleotide drug discovery compared to traditional drugs and will point out some of the current limitations of the technology.

The role of the toxicologic pathologist in the preclinical safety evaluation of biotechnology-derived pharmaceuticals.

Biotechnology-derived pharmaceuticals, or biopharmaceuticals, represent a special class of complex, high molecular weight products, such as monoclonal antibodies, recombinant proteins, and nucleic acids. With these compounds, it is not appropriate to follow conventional safety testing programs, and the preclinical "package" for each biopharmaceutical needs to be individually designed. In addition to standard histopathology, the use of molecular pathology techniques is often required either in conventional animal studies or in in vitro tests. In this review, the safety evaluation of biopharmaceuticals is discussed from the perspective of the toxicologic pathologist, and appropriate examples are given of the use of molecular pathology procedures. Examples include the use of in situ hybridization to localize gene therapy vectors, the assessment of vector integration into genomic DNA by the polymerase chain reaction (PCR), and the use of immunohistochemistry to evaluate the potential cross-reactivity of monoclonal antibodies. In situ PCR techniques may allow for confirmation of the germ cell localization of nucleic acids and may therefore facilitate the risk assessment of germline transmission. Increased involvement with biopharmaceuticals will present challenging opportunities for the toxicologic pathologist and will allow for much greater use of molecular techniques, which have a critical role in the preclinical development of these compounds.