Oligonucleotides, antisense therapy development

In contrast to the biopharmaceuticals discussed thus far (recombinant proteins and gene therapy products), antisense oligonucleotides are manufactured by direct chemical synthesis. Organic synthetic pathways have been developed, optimized and commercialized for some time, as oligonucleotides are widely used reagents in molecular biology. They are required as primers, probes and for the purposes of site-directed mutagenesis. 

The contraindications to and tolerance of interferon-based therapies in the treatment of HCV infection are similar to those described for patients with HBV infection. As for HBV infection, considerable efforts are being made to develop new agents to improve response rates in patients with HCV infection. Direct antiviral strategies with antisense oligonucleotides, ribozymes, and inhibitors of the viral enzymes— polymerase, helicase, and protease—are under investigation. However, it is likely that interferons will continue to serve as the foundation of therapy for HCV infections, with new agents serving as adjuncts. 

It has been shown that the Raf-1 protein serine/threonine kinase is a druggable signaling molecule in cancer therapy (5). and Kasid and co-workers have developed cationic liposomes for in vivo delivery of raf antisense oligonucleotides and raf siRNA into human tumor xenografts established in immunodeficient mice. The authors provide very useful protocols for the preparation of a modified cationic liposome/antisense oligonucleotide formulation as well as toxicology, pharmacokinetics, biodistribution, and anti-tumor efficacy studies in mice (5). 

We and others have demonstrated that Raf-1 protein serine/threonine kinase is a druggable signaling molecule in cancer therapy (1,13,17,21-25). Our laboratory has developed a novel cationic liposomal formulation for systemic delivery of intact raf ASO (LErafAON) to normal and tumor tissues in mice (13,17). The liposome-entrapped raf antisense oligonucleotide (LErafAON) is also the first liposomal ASO drug tested in humans (26,27). Systemically delivered cationic liposomal nanoparticles containing rafsiRNA (LErafsiRNA) also inhibit Raf-1 protein expression in tumor and most normal tissues in human prostate tumor (PC-3)-bearing athymic mice (Fig. 1 and Color Plate 1, see Color Plate Section). 

Among DNA-based drugs, only antisense DNA is currently analyzed by capillary electrophoresis. Antisense DNA therapy requires reliable and convenient methods for sequencing short single-stranded oligonucleotides. A method for phosphorothioate antisense DNA sequencing by capillary electrophoresis coupled to UV detection has been developed based on a modified chain-termination sequencing method.Capillary gel electrophoresis alone or in combination with HPLC is also used for pharmacokinetics study of antisense... 

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