By Doug Macron
Just months after publishing positive non-human primate data on the use of an RNAi-based Ebola virus drug and the receipt of a US government contract to develop the agent, Tekmira Pharmaceuticals has officially named the effort as its third pipeline program.
Meanwhile, the Vancouver, BC-based company continues to make advances with its investigational cancer therapy and its bid to list its shares in the US. The firm, which is currently listed on the Toronto Stock Exchange, expects "to be listed in Nasdaq in the next one to two months," according to officials.
In May, Tekmira and collaborators at the US Army Medical Research Institute of Infectious Diseases reported that siRNAs, delivered using the company's stable nucleic acid lipid particles, could completely protect rhesus macaques from a lethal dose of Ebola (GSN 6/3/2010).
Specifically, a cocktail of modified siRNAs targeting the Zaire Ebola virus L polymerase, viral protein 24, and viral protein 35 were formulated in SNALP molecules and administered to a group of rhesus macaques in 2 mg/kg intravenous infusions after 30 minutes, and on days 1, 3, and 5 following challenge with the virus, they wrote in The Lancet. A second group of monkeys was given the same treatment at 30 minutes, and on days 1, 2, 3, 4, 5, and 6 after viral challenge.
Two of the three monkeys that received the four post-exposure doses of the RNAi therapy were protected from lethal Ebola virus infection, while all of the animals receiving the seven doses were protected, the team wrote.
This finding provides "a model for the treatment of ZEBOV-induced hemorrhagic fever" and shows the potential of RNAi as an "effective post-exposure treatment strategy for people infected with the Ebola virus."
USAMRIID researchers "have been working with Ebola virus for 20 years [and] have never before found a therapeutic agent that could confer complete protection to infected primates," Tekmira President and CEO Mary Murray said last week during a conference call held to discuss the company's second-quarter financials. As such, "we're very excited about moving this program forward as our third therapeutic product candidate."
Also bolstering Tekmira's enthusiasm for the program is a recently received contract from the US Department of Defense Chemical and Biological Defense Program to develop the drug, which has been dubbed TKM-EBOLA.
In July, the company announced that it had received a contract from CBDP to develop an RNAi therapeutic for Ebola virus infection using its proprietary lipid nanoparticle technology. Through the award, Tekmira is eligible to receive up to $34.7 million over the next three years to fund work on TKM-EBOLA through the completion of a phase I study.
The contract, which Tekmira estimated would result in up to $140 million in funding, could be extended beyond this initial period to fund the drug's full clinical development and potential approval by US regulators.
Murray provided few details on the development path for TKM-EBOLA, but noted that the firm is "kicking off" the program and that a "key objective" for the next 12 months or so would be to complete activities necessary for an IND filing.
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At the same time, Tekmira is moving ahead with its second drug candidate, the cancer drug TKM-PLK1, which comprises an siRNA-targeting polo-like kinase 1, a gene linked to the growth of certain solid tumors.
Earlier this month, the company submitted an IND on the drug to the US Food and Drug Administration with the expectation that a phase I trial will begin before year end.
During last week's call, Murray said that additional details on the program, such as specifics on trial design and "our expectations for completion and outcome," will be provided as the start of the clinical study nears.
However, he indicated that of the variety of cancers that TKM-PLK1 could be used to treat, colorectal cancer "is a particularly interesting possibility."
"It is now understood that 50 to 60 percent of [colorectal cancer] patients have a so-called KRAS mutation in their tumor and they don't respond well to current anti-[endothelial growth factor] receptor therapy," he said. "In addition, their tumors may be particularly sensitive to PLK1 knockdown. So this is a very interesting example of an unmet need [that] TKM-PLK1 could address."
In addition to its drug-development efforts, Tekmira is also nearing the end of the process to have its stock listed on the Nasdaq, a goal the company first announced in May.
"We are pursuing a Nasdaq listing for two main reasons," Tekmira CFO Ian Mortimer said during last week's call. "One, in terms of timing, Tekmira and its partners have multiple, value-creating milestones coming in the next few quarters, and a US listing should help broaden Tekmira's exposure to leading North American healthcare investors.
"Second, we believe Tekmira is clearly differentiated from our small-cap RNAi peers by … having multiple, clinical-stage RNAi products, multiple products being advanced by our partners, a strong revenue stream from manufacturing and collaborations, a growing list of partners, and [by being] the only company to complete multiple [business development] deals in 2010 that have a meaningful impact on our cash burn," he added.
"We are making good progress with our [listing] registration and Nasdaq application, and expect to be listed in Nasdaq in the next one to two months."