Sirna Therapeutics President and CEO Howard Robin provided an update about his company's pipeline last week, disclosing new details on the firm's age-related macular degeneration program recently out-licensed to Allergan, as well as non-human primate data from its hepatitis C program.
Robin, speaking to the investment community at the JPMorgan Healthcare Conference in San Francisco last week, also presented the latest timelines for Sirna's permanent hair removal and asthma programs, and said that the company remains on track to sign one major partnership with a big pharma during 2006.
Sirna became the second company to move an RNAi-based drug into the clinic when it began testing the AMD treatment Sirna-027 in humans (see RNAi News, 11/26/2004). Less than six months later, the company was presenting phase I data on the drug and indicated that it was both safe and effective (see RNAi News, 5/6/2005).
"Imagine putting our siRNAs in nanoparticle formulations, putting them ultimately in [Allergan's] Oculex [delivery] system … [for dosing] once every six months or even once a year. Depo injection of an siRNA to treat AMD -- that's the direction we're moving in with Allergan."
Sirna then forged an alliance passing off Sirna-027's development and commercialization rights to Allergan for $5 million up front, as much as $245 million in milestones, and undisclosed worldwide royalties (see RNAi News, 10/7/2005).
At the JPMorgan conference, Robin said that phase II studies of Sirna-027 are now expected to begin in the second quarter of 2006. He also noted that although the drug in its current formulation is expected to yield a less-frequent dosing schedule than other AMD treatments -- a key advantage since these therapies are administered through ocular injections -- Sirna-027 may ultimately take on a very different form in light of the Allergan alliance.
"What's very important about this collaboration is that Allergan is bringing … all of their important drug-delivery technology for ocular delivery," he said. "Imagine putting our siRNAs in nanoparticle formulations, putting them ultimately in [Allergan's] Oculex [delivery] system, and delivering an siRNA [via] depo injection that may be dosed once every six months or even once a year. Depo injection of an siRNA to treat AMD -- that's the direction we're moving in with Allergan."
No so fast, said Michael French, senior vice president of corporate development at Sirna. He told RNAi News this week that Robin was describing "what opportunities could lay in the future with a company like Allergan [and] … their proprietary delivery technologies," and not necessarily "what the delivery of Sirna-027 will be in the future.
"Right now … we're still proceeding [to phase II] with our intravitreal injection," he added.
In late December, Sirna announced that it had begun manufacturing Sirna-AV34, a systemically delivered compound containing multiple siRNAs targeting conserved sequences of the HCV genome, for phase I testing. The company said that it expected to file an investigational new drug application for the drug in the fourth quarter of 2006.
At the time, Sirna said that the HCV drug was incorporating a nanoparticle delivery technology, but didn't specify the nature of the technology. Previously, Sirna had signed a deal to evaluate a technology developed by Protiva Biotherapeutics called SNALP, or stable nucleic acid lipid particle (see RNAi News, 4/8/2005).
In July, Sirna published data demonstrating that the SNALP technology could be combined with siRNAs to significantly knock down of hepatitis B virus in mice (see RNAi News, 7/29/2005). At that time, Robin told RNAi News that Sirna was debating whether to use Protiva's technology or its own in clinical trials of a HCV drug candidate.
Last week in San Francisco, however, Robin revealed that Sirna has opted to keep things in house.
Sirna expects to form "at least one major corporate partnership this year … and I think that will be a significant partnership with big pharma."
During the conference, Robin noted how Sirna has "invented nanoparticle-based technologies that allow us to get 70-80 percent of our [siRNA] dose inside … hepatocytes." These particles, he said, "are spherical in shape, where the siRNAs are part of the structure of the nanoparticle. As the nanoparticle gets into the endosome, it changes shape from a sphere to a cylinder [and] … the siRNAs are then released … and enter the cytoplasm."
Using this technology, Sirna recently tested the efficacy of siRNAs against HCV in non-human primates.
"We took three animals and infected them with an HCV virus and we administered our siRNA nanoparticle formulation with a multi-siRNA compound -- two different sequences both targeting the conserved region of the [virus'] genome," Robin said during the conference. "The [first] objective was … proof of principle [to] demonstrate the delay in the onset of establishment of a virus. The second objective was … [to] demonstrate the knockdown of viral load after the infection was established."
Robin said that one of the primates was left untreated and developed "a significant viral titer after four weeks very much consistent with the historical norms with this disease." The other two animals were then treated with the siRNA therapy over about a week and a half, which "delayed the onset of established infection by three weeks."
Robin said that Sirna then began dosing the previously untreated primate in order to see if the virus could be knocked down after having been established. "With three doses over the course of about a week and a half, we were able to get a 99.5 percent reduction in viral titers," he said. "We are now monitoring that animal … for duration of effect and to see when … viral titers [come] back up." All animals were given doses of 3 mg/kg.
With these positive animal data in hand, the company intends to use its own delivery technology with its HCV clinical candidate, a Sirna spokeswoman confirmed to RNAi News this week.
At the JPMorgan conference, Robin confirmed Sirna's previous target to have an IND filed on Sirna-AV34 in the fourth quarter, and said that the company has a pre-IND meeting planned with US regulators in February.
Air, Hair, and a Deal
Also at JPMorgan, Robin noted that Sirna's asthma program, which is examining the use of lipid nanoparticle-based siRNA formulations, is progressing, and that "we will be selecting by the end of this year a clinical candidate for asthma." He also said that the company is on-track to file an IND on a hair-removal candidate in the fourth quarter.
Finally, Robin said that Sirna continues to expect to establish "at least one major corporate partnership this year … and I think that will be a significant partnership with big pharma."
-- Doug Macron ([email protected])