The Effectiveness and Value of Deflazacort and Exon-Skipping Therapies for the Management of Duchenne Muscular Dystrophy.

DISCLOSURES: Funding for this summary was contributed by Arnold Ventures, Commonwealth Fund, California Health Care Foundation, National Institute for Health Care Management (NIHCM), New England States Consortium Systems Organization, Blue Cross Blue Shield of Massachusetts, Harvard Pilgrim Health Care, Kaiser Foundation Health Plan, and Partners HealthCare to the Institute for Clinical and Economic Review (ICER), an independent organization that evaluates the evidence on the value of health care interventions. ICER's annual policy summit is supported by dues from Aetna, America's Health Insurance Plans, Anthem, Allergan, Alnylam, AstraZeneca, Biogen, Blue Shield of CA, Cambia Health Services, CVS, Editas, Express Scripts, Genentech/Roche, GlaxoSmithKline, Harvard Pilgrim, Health Care Service Corporation, Health Partners, Johnson & Johnson (Janssen), Kaiser Permanente, LEO Pharma, Mallinckrodt, Merck, Novartis, National Pharmaceutical Council, Premera, Prime Therapeutics, Regeneron, Sanofi, Spark Therapeutics, and United Healthcare. Agboola, Fluetsch, Rind, and Pearson are employed by ICER. Lin reports support from ICER during work on this economic model and grants from Mount Zion Health Fund, National Institutes of Health (National Cancer Institute and National Heart, Lung, and Blood Institute), and the Tobacco-Related Diseases Research Program, unrelated to this work. Walton reports support from ICER for work on this economic model and unrelated consulting fees from Baxter.

Systematic evaluation of 2'-Fluoro modified chimeric antisense oligonucleotide-mediated exon skipping in vitro.

Antisense oligonucleotide (AO)-mediated splice modulation has been established as a therapeutic approach for tackling genetic diseases. Recently, Exondys51, a drug that aims to correct splicing defects in the dystrophin gene was approved by the US Food and Drug Administration (FDA) for the treatment of Duchenne muscular dystrophy (DMD). However, Exondys51 has relied on phosphorodiamidate morpholino oligomer (PMO) chemistry which poses challenges in the cost of production and compatibility with conventional oligonucleotide synthesis procedures. One approach to overcome this problem is to construct the AO with alternative nucleic acid chemistries using solid-phase oligonucleotide synthesis via standard phosphoramidite chemistry. 2'-Fluoro (2'-F) is a potent RNA analogue that possesses high RNA binding affinity and resistance to nuclease degradation with good safety profile, and an approved drug Macugen containing 2'-F-modified pyrimidines was approved for the treatment of age-related macular degeneration (AMD). In the present study, we investigated the scope of 2'-F nucleotides to construct mixmer and gapmer exon skipping AOs with either 2'-O-methyl (2'-OMe) or locked nucleic acid (LNA) nucleotides on a phosphorothioate (PS) backbone, and evaluated their efficacy in inducing exon-skipping in mdx mouse myotubes in vitro. Our results showed that all AOs containing 2'-F nucleotides induced efficient exon-23 skipping, with LNA/2'-F chimeras achieving better efficiency than the AOs without LNA modification. In addition, LNA/2'-F chimeric AOs demonstrated higher exonuclease stability and lower cytotoxicity than the 2'-OMe/2'-F chimeras. Overall, our findings certainly expand the scope of constructing 2'-F modified AOs in splice modulation by incorporating 2'-OMe and LNA modifications.

Gene therapy for spinomuscular atrophy: a biomedical advance, a missed opportunity for more equitable drug pricing.

An experimental approach for gene therapy of spinomuscular atrophy has been reported to prevent development of the neuromuscular features of this lethal and previously untreatable disorder. The approach involves treatment of patients suffering from SMN1-associated infantile form of the disease with a splice-switching antisense oligonucleotide (ASO) that corrects aberrant splicing of the nearly identical SMN2 gene to allow the generation of functional SMN protein, thereby mitigating the development of the disease. This technique represents the first apparently effective therapy for spinal muscular atrophy (SMA) and an important documentation for ASO technology for therapy of neurodegenerative disease. These results with one form of SMA are likely to be relevant for similar applications to other SMA types and are likely to inspire application to a number of other intractable neurodegenerative diseases such as Huntington's disease, amyotrophic lateral sclerosis and possibly even the extremely common Parkinson's and Alzheimer's diseases and others. Nevertheless, the scientific and medical importance of this advance is marred by a pricing policy by the corporate sponsors that may complicate accessibility of the drug for some desperate patients.

Splice modification to restore functional dystrophin synthesis in Duchenne muscular dystrophy.

In little more than a decade, induced exon skipping as a therapy to treat Duchenne muscular dystrophy (DMD) has progressed from a concept tested in vitro, to pre-clinical evaluation in mouse and dog models, and recent completion of Phase I clinical trials in man. There is no longer any doubt that antisense oligomers can redirect dystrophin gene processing and by-pass protein truncating mutations after direct injection into muscle. Proof-of-concept has been demonstrated in human dystrophic muscle, with trials in Leiden and London showing that two different oligomer chemistries can restore the reading-frame in selected DMD patients by excising dystrophin exon 51. Systemic delivery of both oligomer types into DMD patients has commenced with promising results but it remains to be established if this therapy will have measurable clinical benefits. Targeted removal of exon 51 will only be directly applicable to about one in ten DMD individuals, and the immediate challenges include development of appropriate and effective delivery regimens, and extending splice-switching therapies to other dystrophin gene lesions. The success of induced exon skipping has spawned a number of "fusion therapies", including vector-mediated dystrophin exon skipping and ex vivo viral delivery of splice-switching antisense molecules into myogenic stem cells, followed by implantation, which may address long term oligomer delivery issues. This review summarizes the pivotal events leading to the completion of the first proof-of-concept trials and speculates on some of the scientific, ethical, regulatory and commercial challenges facing targeted exon skipping for the treatment of DMD.

[Biotechnologic drugs and chemotherapy for infectious diseases]. / Fármacos biotecnológicos y quimioterapia antiinfecciosa.

Developments in biotechnology in recent years have enabled the discovery of new pharmacological agents for the treatment and prophylaxis of infectious diseases. The agents obtained from these biotechnological procedures possess specific characteristics which significantly distinguish them from drugs obtained by chemical synthesis. These properties cover the entire development process, from investigation and production up to their administration to patients. The pharmokinetics of these preparations influence their administration routes and dosage regimens. The discovery of these drugs has led to major advances in the treatment and prophylaxis of infectious processes which until very recently had no effective treatment. The investigation and production of these drugs requires the use of highly technical resources resulting in high costs and therefore a more expensive drug on the market compared to other drugs. Nevertheless, well documented pharmoeconomic studies show that the use of this type of drug for certain symptoms may be highly cost effective. This article includes some of the possible applications of biotechnology in the infectious disease field, although the current situation indicates that more detailed and broader applications may be elaborated on in ensuing issues. The future of these drugs in chemical therapy for the treatment and prophylaxis of infectious diseases is exceedingly promising and many of these drugs are currently under laboratory investigation, more so than those under development from a chemical synthesis approach.

Synthesis and characterization of composite nucleic acids containing 2', 5'-oligoriboadenylate linked to antisense DNA.

Composite nucleic acids, known as 2-5A antisense chimeras, cause the 2-5A-dependent ribonuclease (RNase L) to catalyze the specific cleavage of RNA in cell free systems and in intact cells. Such 2-5A antisense chimeras are 5'-monophosphorylated, 2,'5'-linked oligoadenylates covalently attached to antisense 3',5'-oligodeoxyribonucleotides by means of a linker containing two residues of 1,4-butanediol phosphate. Here we report a fully automated synthesis of 2-5A antisense chimeras on a solid support using phosphoramidite methodology with specific coupling time modifications and their subsequent purification by reverse-phase ion-pair and anion exchange HPLC. Purified 2-5A antisense chimeras were characterized by [1H]NMR and [31P]NMR, MALDIMS, and capillary gel electrophoresis. The synthetic 2',5'-linked oligoadenylate showed no phosphodiester isomerization to 3',5' during or after synthesis. In addition, we have developed facile methodologies to characterize the chimeras using digestion with various hydrolytic enzymes including snake venom phosphodiesterase I and nuclease P1. Finally, Maxam-Gilbert chemical sequencing protocols have been developed to confirm the entire sequence of these chimeric oligonucleotides.