It has been a long and turbulent road for Marqibo (vincristine sulfate liposome injection), but South San Francisco-based Talon Therapeutics Inc. finally brought it over the goal line. The product received FDA accelerated approval Thursday based on a single-arm study for the treatment of adult patients with Philadelphia chromosome negative (Ph-) acute lymphoblastic leukemia (ALL) in second or greater relapse or whose disease has progressed following two or more anti-leukemia therapies.

"The approval is a significant milestone for the company, and we are delighted that all our hard work over a five-year period by a small dedicated team has finally paid off," Steven Deitcher, president and CEO of Talon, told BioWorld Today. Vincristine, a microtubule inhibitor, is FDA-approved for ALL and Non-Hodgkin's Lymphoma (NHL) and is widely used in combination regimens for treatment for a variety of adult and pediatric hematologic and solid tumor malignancies. "We were able to lever the important properties of this well-known compound with our Optisome nanoparticle encapsulation technology, to provide prolonged circulation of vincristine in the blood," Deitcher added.

Marqibo was originally developed by Burnaby, British Columbia-based Inex Pharmaceuticals Inc., which ran into trouble when the product was rejected by the FDA under the accelerated approval pathway. Back in 2005, the drug earned a not-approvable letter in non-Hodgkin's lymphoma two months after ODAC said a randomized trial would be needed for approval. (See BioWorld Today, Dec. 2, 2004, and Jan. 20, 2005.)

Two years after this event, Inex spun out its entire biotechnology business, assets and intellectual property into Tekmira Pharmaceuticals Corp. (NASDAQ:TKMR) of Vancouver, British Columbia. (See BioWorld Today, May 2, 2007.)

Marqibo, along with two other liposomal chemotherapy products, Alocrest (liposomal formulation of the chemotherapy drug vinorelbine) and Brakiva (liposomal formulation of the chemotherapy drug topotecan), were licensed from Tekmira to Talon (formerly Hana Biosciences). Tekmira will now be eligible to receive a $1 million milestone payment based on the FDA approval of Marqibo and will receive royalty payments based on Marqibo's commercial sales.

Going forward Talon expects to begin marketing the drug in the U.S. in the first quarter of 2013 and will look for potential partners to market Marqibo in other jurisdictions, Deitcher said.

The company has also started enrolling patients in a Phase III confirmatory study, known as the HALLMARQ study, will administer Marqibo in adults (60 and older) with newly diagnosed Ph- ALL. (See BioWorld Today, June 6, 2012.)

Based on prior FDA discussions, the company received a special protocol assessment (SPA) agreement for the large, randomized Phase III trial in front-line adult elderly ALL patients with sites currently open for enrollment. It is expected that about 400 patients will be enrolled globally.

In addition to the HALLMARQ study in front-line adult elderly ALL, Marqibo also is being evaluated in an ongoing Phase III trial in front-line adult elderly aggressive non-Hodgkin's lymphoma conducted by the German High Grade Non-Hodgkin's Lymphoma Study group, and in a Phase I trial in pediatric cancers, including ALL, being conducted by the National Cancer Institute.

Talon has received orphan drug and fast-track designations for Marqibo for the treatment of adult ALL from the FDA. Marqibo has also received orphan drug designation in adult ALL from the European Medicines Evaluation Agency. (See BioWorld Today, July 19, 2011.)

During the day the share value of Talon (OTCQB:TLON) was up about 10 percent but it drifted back to close up 1 cent at 98 cents Thursday.