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Sirna Outlines Pipeline, New RNAi Tech; CytRx Hints at Leaving RNAi Drugs Sector

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Sirna Therapeutics President and CEO Howard Robin painted a rosy picture of his company this week at the Rodman & Renshaw Techvest 7th Annual Healthcare Conference held in New York this week, providing updates on its drug-development efforts and highlighting a technology designed to hit multiple genes with a single RNAi oligo.

Contrasting Robin's talk was one given by Steven Kriegsman, president and CEO of CytRx, whose presentation focused primarily on his company's small-molecule drug programs, and who told RNAi News on the sidelines of the conference that CytRx is considering handing off its RNAi-based drug programs to a spin-out company.

The View from Sirna

Speaking to the investment community at the conference, Robin provided an overview of RNAi and touted the therapeutic potential of modified siRNA, and touched on the company's efforts in hepatitis C, which has become Sirna's lead therapeutic program now that its age-related macular degeneration drug Sirna-027 has been out-licensed to Allergan (see RNAi News, 10/7/2005).

According to Robin, Sirna is planning to meet with the US Food and Drug Administration to talk about an investigational new drug application on a hepatitis C drug before the end of the year, and expects to file the IND in the third quarter of 2006.


Though CytRx was an early-mover in the RNAi-based therapeutics field, its interest in the area has apparently been waning lately as it focuses more on near-term small-molecule drug opportunities.

Robins' discussion of Sirna's efforts in respiratory disease, however, was the highlight of his presentation, as he described the company's work in developing aerosol-delivery technologies. In preclinical studies, he said, a 60-microgram dose of a modified siRNA was detected in the lungs as long as 3 days after aerosol administration, and has been seen to penetrate B lymphocytes; macrophages and monocytes; endothelial and epithelial cells; and fibroblasts.

Robin also noted that the company has identified several targets as part of its asthma program, including interleukin-4 (IL-4), IL-4 receptor (IL-4R), IL-13, and IL-13R. In animal models of asthma, a 1 mg/kg dose of a modified siRNA targeting IL-4R alpha achieved a 70-percent reduction in lung inflammation and an 80-percent inhibition in airway constriction.

With these data in hand, Robin said, Sirna is currently in discussions with a number of potential collaborators, and expects to form at least one additional partnership over the next six months -- although such a deal may or may not be in the respiratory disease area. During a conference call to discuss Sirna's third-quarter financial results last week, Robin noted that the company is also talking to possible partners about alliances in the oncology or antiviral fields.

He told RNAi News after his Rodman & Renshaw talk that Sirna may advance its asthma program into the clinical as early as 2007.

As this work moves ahead, Sirna is also developing what it calls "multifunctional" short-interfering nucleic acids -- essentially siRNAs modified in such a way that both the sense and antisense strands can be used to silence a distinct gene each. Sirna's Vice President of Legal Affairs and Chief Patent Counsel Bharat Chowrira, who attended the Rodman & Renshaw conference with Robin, noted that if sufficient homology exists between sequences, these multifunctional siNAs can potentially target more than two genes.

Robin added that although Sirna is investigating the use of multifunctional siNAs in all indications, the "first place you'll [likely] see it in a significant way is in asthma."

Will CytRx Stay in the RNAi Game?

Although CytRx was an early-mover in the RNAi-based therapeutics field, snapping up the rights to key University of Massachusetts RNAi-related intellectual property in the areas of obesity, type II diabetes, and amyotrophic lateral sclerosis in early 2003, the company's interest in the area has apparently been waning lately as it focuses more on near-term small-molecule drug opportunities.

During his presentation at the Rodman & Renshaw conference, Kriegsman listed as CytRx's core foci small molecule drugs, RNAi drug discovery, and its DNA vaccine for HIV -- conspicuously leaving RNAi-based drugs absent, although he did note that the company has "RNAi capabilities" for therapeutics.

Alnylam Plans to Run Phase I Trial of Respiratory
Syncytial Virus Drug ALN-RSV01 In US, Europe

Alnylam Pharmaceuticals Senior Vice President of Business Development Vincent Miles also presented at the Rodman & Renshaw Techvest 7th Annual Healthcare Conference, giving an overview of RNAi and the company.

During his presentation, he provided some additional details on Alnylam's planned phase I trials of its respiratory syncytial virus drug, called ALN-RSV01. According to Miles, the company will run a phase I trial in the US that will enroll 35 healthy male volunteers. This placebo-controlled study will evaluate a single dose of the drug, and will evaluate safety and pharmacokinetics.

Alnylam is also planning a broader phase I trial in Europe, which will enroll 57 healthy male volunteers, and test both single and multiple doses of ALN-RSV01. This placebo-ascending dose trial will evaluate safety and pharmacokinetics, as well.

The company expects to begin dosing patients in the phase I study before the end of the year.

Jack Barber, senior vice president of drug development at CytRx, added during Kriegsman's talk that "for the most part," the company uses RNAi for target identification and validation in its small-molecule drug discovery efforts.

During a breakout session with investors, discussion was limited to CytRx small-molecule and DNA vaccine work, and Kriegsman noted that the company's board is primarily "focused on getting the [ALS] drug [arimoclomol] to market." When asked about CytRx's plans in the RNAi drugs area after the breakout session, Kriegsman told RNAi News that the company is considering spinning out a separate, publicly traded, pure-play RNAi drugs firm.

While he didn't comment specifically on possible timing for such a move, he said the company is "working on it now." He declined to answer additional questions from RNAi News, citing time constraints.

-- Doug Macron ([email protected])

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