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Mar 15, 2010 (Vol. 30, No. 6)

Oligo Therapeutics Enriching Pipelines

As Development Escalates, Delivery Strategies, Chemistries, and Modifications Also Improve

  • Click Image To Enlarge +
    Agilent Technologies' GMP oligonucleotide API manufacturing plant in Boulder, CO

    Market research figures compiled by Agilent Technologies reveal that in 2009, $407 million in direct financing was targeted to the development of oligonucleotide therapeutics in the U.S. This figure represents a combination of publically announced venture capital, private placement, IPO, secondary financing, and up-front collaboration payments.

    The total deal value for therapeutic oligos in 2009—including up-front payments and potential milestone royalties—approached $2.8 billion, about the same as in 2006 and less than half the total for 2008. This total covers the full spectrum of oligo-based drugs: miRNAs, siRNAs, aptamers, decoys, antisense, immunostimulatory oligos, and other related drug classes.

    Continuing an upward trend begun in 2003, the number of oligo therapeutic programs has increased each year, growing to 231 in 2009, representing a more than 8% increase from 2008.

    As the number of oligo therapeutics in development continues to increase, so too does their complexity, the scale of oligo manufacturing to support late-stage development and commercialization programs, and the range of chemistries, modifications, delivery strategies, and purification and analytical methods. This diversity will be evident in the scope of presentations at IBC’s upcoming “TIDES” conference.

    At the meeting, Agilent will unveil a novel technology for large-scale RNA deprotection. The technology combines chemical and engineering solutions that overcome the problems caused by the exothermic nature of conventional deprotections.

    Heat-induced degradation of RNA during deprotection has, to date, hindered the ability to scale RNA production above 200 grams. Agilent has coupled on-column cleavage of RNA from the solid support with removal of the deprotecting groups in a semi-continuous, scalable process. The cleavage step involves pumping reagents through the synthesis bed and into a holding vessel. For deprotection, the contents of this vessel are continuously combined with deprotection reagents in a temperature-controlled mixed stream.

    Paul Metz, director of operations at Agilent, describes this technology as another step in the company’s goal of transforming discrete steps in the manufacturing process into more continuous, closed process steps that facilitate automation and large-scale production.

  • Scaling Up

    Click Image To Enlarge +
    Noxxon Pharma has developed a standard production process to synthesize natural D-configured oligonucleotides.

    Metz reports that beginning in late 2009 and continuing into this year, Agilent has seen a growing number of late-stage programs for oligo APIs. These include scale up and supply of Phase III trial materials through to full process validation and commercial launch. The company’s new large-scale, multipurpose GMP facility in Boulder, Colorado, was designed to accommodate kilogram-scale oligo production. The plant has capacity in the low hundreds of kilograms per year and is on-stream and fully qualified. Agilent anticipates several projects moving forward into large-scale production in the 2011–2013 timeframe.

    Exemplifying some of the challenging aspects of producing larger quantities of atypical oligonucleotides is the experience of Noxxon Pharma, which has taken its Spiegelmer® oligos into clinical development. NOX-E36 is completing a Phase I trial in inflammation and will enter a Phase II study in 2010. NOX-A12, designed to stimulate autologous stem cell recruitment, is also finishing up a Phase I trial and will begin a proof-of-concept Phase II study this year.

    In December, the company announced the identification of a Spiegelmer with picomolar affinity and high selectivity for a target being pursued in collaboration with Eli Lilly for the treatment of migraine headache.

    Spiegelmers are mirror-image, L-configured oligos composed of the L-isomer of ribonucleic acid. They bind to a biological target in a manner similar to antibody-antigen recognition, explains Stefan Vonhoff, Ph.D., vp of chemistry, manufacturing and control at Noxxon. Because they are not degraded by naturally occurring nucleases, Spiegelmers offer an attractive in vivo stability profile. They are unmodified L-RNA oligonucleotides that are synthesized using standard production processes established for natural D-configured oligos.

    Initially, “the development of a scalable and cost-efficient manufacturing process for the L-RNA monomers” was a challenge, says Dr. Vonhoff. Today, the monomers are synthesized at multikilogram scale and the key raw material, L-ribose, has turned into a chemical commodity produced at ton scale for the manufacturing of antiviral drugs such as clevudine, which is used to treat hepatitis B.

    Now, notes Dr. Vonhoff, Noxxon’s main process-development focus is on GMP manufacturing of Spiegelmers, in which efficient purification strategies are key to producing the drug substance at a consistently high quality. Noxxon has initiated a program with a CMO partner “to improve loading efficiency while maintaining the quality of the product,” says Dr. Vonhoff. The main impurities produced during the manufacture of Spiegelmers are “failure sequences,” he adds. “Due to their unnatural L-configuration, those N(+)-mers and N(-)-mers” are unlikely to exert off-target effects.

    As therapeutic oligos move through preclinical testing into human studies and on to commercialization there is an increasing need for higher throughput analytical methods and strategies for assessing the composition and purity of larger amounts of compound isolated from biological samples such as blood and tissue. Analytical processes focus on identifying potentially active metabolites, quantifying and identifying impurities, and characterizing the pharmacokinetic properties of the drug as part of required ADME studies.

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