By Doug Macron
Tekmira Pharmaceuticals is on track to start enrolling patients in a phase I study of its solid tumor therapy TKM-PLK1, and is in talks with the National Cancer Institute over a possible collaboration on using the drug in liver cancer, the company's top official said this week.
Meanwhile, Tekmira continues to work on new formulations of its phase I hypercholesterolemia drug TKM-ApoB, which will not re-enter human testing this year as previously disclosed, President and CEO Mark Murray said.
TKM-PLK1 is comprised of an siRNA designed to silence polo-like kinase 1 — a cell cycle protein implicated in tumor cell proliferation — and Tekmira's proprietary lipid nanoparticles. In September, the US Food and Drug Administration approved the company's investigational new drug application to begin human trials of the agent as a therapy for solid tumors outside of the liver.
With that regulatory milestone passed, Tekmira is set to begin enrolling patients before the end of the year — in line with previous guidance — at three US cancer centers, Murray said during a conference call held to discuss the firm's third-quarter financial results.
"The study will be a traditional phase I oncology trial evaluating the safety, tolerability, and pharmacokinetics of TKM-PLK1 in a multi-dose, dose-escalation trial to establish maximum tolerated dose in patients with a variety of solid tumor types," he said.
Given PLK1's involvement in a variety of tumors, including colorectal, breast, and non-small cell lung cancers, Tekmira is also "looking at opportunities to further expand the development of TKM-PLK1," including conducting a clinical trial in liver cancer patients with the NCI, he noted.
"A trial involving the NCI could provide an opportunity to more rapidly collect clinical data … in a second indication," Murray said. "This trial would be run in collaboration with the surgical branch of the NCI in liver cancer patients where tumor biopsies allowing measurement of RNAi drug activity may be more readily available."
Additional details about such an arrangement will be provided as "discussions with the NCI progress," he said.
In terms of Tekmira's in-house development plan for TKM-PLK1, Murray noted that the company is in the process of identifying "a particular tumor type to go forward" with into phase II.
"We're hoping to get some inkling of that in the phase I" study, he noted, adding that preclinical data suggest colorectal cancer may be a promising indication.
Meanwhile, Tekmira continues to keep TKM-ApoB in a holding pattern as its works on "improved" versions of the drug using advancements made with its lipid nanoparticle technology.
The drug was Tekmira's first product candidate to enter human testing when it moved into phase I testing in 2009 (GSN 7/9/2009). In January 2010, however, the company stopped that study early after a patient enrolled in it experienced side effects consistent with immune stimulation triggered by the siRNA component (GSN 1/14/2010).
Shortly thereafter, Murray publicly stated that Tekmira had developed a "more sophisticated screening assay" to identify better apoB-targeting siRNAs, which would be used with improved versions of its delivery vehicles, setting the company up to restart the phase I program with a next-generation version of TKM-ApoB (GSN 2/11/2010).
In September, however, plans for the new trial were put on hold at least until 2011 after disappointing results in preclinical experiments (GSN 9/16/2010).
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"Although we initially planned to be back in the clinic before year-end, we decided to take additional time before locking down a new [lipid nanoparticle] formulation," Murray said during this week's call. "In our view, tolerability is at least as important as potency, and we seek to optimize both."
He noted that the delay with TKM-ApoB "has no impact on the status of any of our other programs," including the firm's third pipeline product, the Ebola therapy TMK-Ebola.
Murray said that Tekmira is on track to file an IND for the drug in 2011, reflecting an acceleration in the program since the company received a contract from the US Department of Defense Chemical and Biological Defense Program to develop it.
Through the contract, 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 company previously said that it could realize as much as $140 million in total funding through the contract, which could be extended beyond this initial period to fund the drug's full clinical development and potential FDA approval.
For the three-month period ended Sept. 30, Tekmira narrowed its net loss to $2.7 million, or $0.26 per share, from a year-ago loss of $2.8 million, or $0.27 per share.
Revenues in the quarter surged to $10.4 million from $3.3 million in the same period last year, in part reflecting a $5.9 million license fee related to Tekmira's deal with Hana Biosciences for three non-RNAi chemotherapy drug candidates left over from before the company became a pure-play RNAi shop.
In the third quarter, Tekmira also received a $500,000 milestone payment from Alnylam Pharmaceuticals, which is using Tekmira's lipid nanoparticle technology in its phase I transthyretin-mediated amyloidosis drug ALN-TTR01.
Research, development, collaboration, and contract expenses in the quarter climbed to $5.2 million from $4.4 million, primarily because of costs related to the development of TKM-Ebola.
General and administrative costs, meantime, rose to $1.5 million from $900,000 the year before, largely due to Tekmira's efforts to have its stock listed on the Nasdaq exchange, which occurred this week.
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