By Deena Beasley
(Reuters) - Talon Therapeutics Inc, largely backed by venture capital, is banking on U.S. regulatory approval for its version of a nearly 50-year-old chemotherapy drug, which it expects will open the door to new licensing deals.
The Food and Drug Administration is set to decide by August 12 on Talon's application for Marqibo for treating certain adults with acute lymphoblastic leukemia (ALL) who have failed at least two other therapies.
An FDA advisory committee recommended in March that the agency approve the drug, even though trial data did not compare the drug's effectiveness with that of another treatment.
Marqibo is a targeted version of vincristine, a generic cancer drug first approved by the FDA in 1963, that uses liposomal, or fat, bubbles to prolong the drug's circulation in the blood and accumulation at the tumor site.
"We have corrected flaws in vincristine ... Our doses are two to three times larger," said Talon Chief Executive Steven Deitcher in an interview. "We can dose intensify with a side effect profile comparable to the original drug."
Talon licensed Marqibo in 2006 after the FDA in 2005 turned down an application for the drug, filed by two other companies, to treat relapsed non-Hodgkin's lymphoma.
Standard vincristine, derived from a type of periwinkle flower, is used in chemotherapy regimens for a range of blood cancers, but the dose must be capped due to side effects, including nerve damage and fever.
Talon estimates that if Marqibo's current application is approved, about 2,000 U.S. patients per year would be eligible for strict on-label use. That number could reach as high as 2 million if the drug were to replace standard vincristine, according to the company.
"Based on market research ... assuming some sort of premium pricing strategy, this could be a $100 million a year sales opportunity based on the initial label," Deitcher said.
Talon is conducting larger comparison trials of Marqibo in newly diagnosed adult ALL patients and in newly diagnosed adults with aggressive lymphoma.
The National Cancer Institute is conducting an early-stage trial in pediatric cancers, including ALL.
Talon's remaining pipeline is in an earlier stage of development, including versions of generic chemotherapy drugs topotecan and vinorelbine that also employ its "optisome" technology for more concentrated dosing.
Deitcher said he expects Marqibo to eventually be combined with biologic drugs being developed for treatment of ALL, such as Amgen Inc's experimental antibody blinatumomab.
He said Talon is in talks with several potential partners for commercialization of Marqibo but is also moving forward with plans to establish its own sales force so that the drug could be launched in the first quarter of next year.
"There has been interest by companies well-established in the oncology space ... We are also in discussions with companies that wish to get into the oncology space," Deitcher said.
He said that Talon, majority-owned by Warburg Pincus and Deerfield Management, has access to $57 million in preexisting financing that can be used for the commercial launch.
The CEO also said Talon could have the option of licensing Marqibo for treating other types of cancer or as a technology platform used to optimize other chemotherapy drugs.
"An approval of Marqibo more or less validates the technology," Deitcher said. "It opens up a broad spectrum of opportunities."
(Reporting By Deena Beasley; Editing by Michele Gershberg and Steve Orlofsky)