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Cell Therapeutics Poised to Play in RNAi Space As It Hands Off siRNA Delivery Tech to Spin-Out

Cancer drug developer Cell Therapeutics this week announced that it would be stepping into the RNAi ring by creating and eventually spinning out a company focusing on a technology that may have applications in siRNA delivery.
The spin-out, Aequus BioPharma, will take over development of Cell Therapeutics’ so-called genetic polymer technology, which comprises a recombinant DNA process that ligates a secretion sequence with a biologically active protein sequence and a poly-amino acid sequence.
Cell Therapeutics said this approach results in a “novel, unique, and patentable gene,” and is expected to be useful in extending the half-life of therapeutic proteins. The company also sees potential for the technology in overcoming the well-known key hurdle facing RNAi-based drug development: delivery.
"In addition to its application in producing lower-cost follow-on biologics, we believe this recombinant technology might be utilized to … deliver small inhibitors of RNA to their cellular targets in a wide array of malignant, inflammatory, or infectious diseases,” James Bianco, president and CEO of Cell Therapeutics, said in a statement.
Speaking to the financial community at this year’s BIO CEO & Investor conference in New York, Bianco noted that Cell Therapeutics has been developing the genetic polymer technology for more than three years as part of its ongoing efforts to develop polymer-based drug-delivery approaches.
“We have a lot of in-house core competencies and expertise [with the biodegradable polymer] polyglutamate — polyglutamic acid polymers — and we initially tried to make polyglutamic acid through recombinant techniques instead of the traditional chemical ways of making polymers,” he said during his presentation.
“We were successful in doing that in E. coli, and once you had a sequence for making and expressing polyglutamic acid, you could then ligate that to a biologic moiety that you’re interested in,” Bianco added.
However, “when we did that in our pre-clinical studies, we immediately saw that the half-life was very short and it all got taken up into the reticuloendothelial system, i.e. macrophages or cells that express estrogen receptors, et cetera,” Bianco said.
This work indicated that “polyglutamic acid [is] a very useful polypeptide for targeting potential agents to inflammatory cells like macrophages” and prompted researchers at Cell Therapeutics to take a look at other poly-amino acids that would be “non-immunogenic, non-biologically active, and, importantly, would improve the half-life characteristics of whatever biologic agent you wanted to ligate it to,” Bianco said. “In fact, they’ve done that quite efficiently” with the genetic polymer technology.
Although the primary focus of Aequus will be to develop the technology for therapeutic proteins, “the fact that we can … potentially … improve the half-life of [siRNAs] … has really stimulated a lot of interest from big pharma,” Bianco said during his BIO-CEO presentation, adding that “multiple discussions” are taking place regarding licensing the technology for delivering RNAi oligos.
Noting that his firm is “not a protein therapeutics company,” Bianco said that Cell Therapeutics is currently recruiting for Aequus a scientific and management team, which will likely include former members of the Immunex team that helped develop and launch the biologic arthritis drug Embrel.
In 2002, biotech giant Amgen acquired Immunex for $16 billion in a deal that was largely driven by the success of Enbrel.
Bianco added that “there has been a lot of interest in Aequus from a venture capital perspective as well,” and that Cell Therapeutics is aiming to capitalize Aequus, spin it out with its own management team, and establish a corporate partnership for the genetic polymer technology sometime this year.

"In addition to its application in producing lower cost follow-on biologics, we believe this recombinant technology might be utilized to develop novel biologics and also deliver small inhibitors of RNA to their cellular targets in a wide array of malignant, inflammatory, or infectious diseases.”

A spokeswoman from Cell Therapeutics said the company could not comment on Aequus beyond Bianco’s statements at BIO-CEO, citing “patent issues.”
Will Enablers Deliver?
Once it has been formed, Aequus will join the growing ranks of companies looking to operate in the RNAi drugs space as a therapeutics enabler rather than a therapeutics developer.
Indeed, at this stage of the game, the primary challenge facing RNAi-based therapies continues to be delivering them to the right places in the body, and a number of companies are focusing their energies on developing technologies to overcome this issue.
Protiva Biotherapeutics, for example, has been shopping its so-called SNALP delivery technology for years (see RNAi News, 11/7/2003). In fact, the company has had such success with SNALPs that it is currently embroiled in a legal battle with one-time parent Inex Pharmaceuticals over the technology’s rights (see RNAi News, 12/7/2006).
And late last month, RNAi News reported on the formation of Cequent Pharmaceuticals, which is developing a bacteria-based delivery technology for siRNAs that it expects will raise the interest of companies developing RNAi drugs (see RNAi News, 1/25/2007).
Meanwhile, North Carolina-based BioDelivery Sciences has conducted preclinical work evaluating the ability of its Bioral technology to deliver influenza-targeting siRNAs for an undisclosed collaborator (see RNAi News, 8/10/2006), and Copernicus Therapeutics continues to hone a gene therapy nanoparticle technology for siRNA delivery in hopes of wooing a licensing partner (see RNAi News, 7/13/2006).

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