Just ahead of the three-day weekend, the FDA granted approval of antibiotic dalbavancin, a drug that ended its long and winding development road by becoming the first qualified infectious disease product (QIDP) to win approval, getting the nod for use in acute bacterial skin and skin structure infections (ABSSSIs) caused by gram-positive microorganisms, including the dreaded methicillin-resistant Staphylococcus aureus.

The decision, posted by the agency late Friday afternoon, came ahead of the May 26 PDUFA date set for the long-acting, intravenous lipoglycopeptide candidate, which will be branded Dalvance.

Durata Therapeutics Inc.'s stock (NASDAQ:DRTX) was trading at $16.89 when halted ahead of the FDA's announcement.

Chicago-based Durata, which submitted the new drug application (NDA) in September, was formed in 2009 specifically to continue the development of dalbavancin, a drug once owned by Pfizer Inc. – inherited in the New York-based big pharma's 2005 buyout of Vicuron Pharmaceuticals Inc. The candidate, which had met its primary endpoint in treating complicated skin infections in a phase III noninferiority study involving more than 800 subjects, got hung up in the FDA's then-changing guidelines for antibiotic approval and ended up slapped with an approvable letter in 2007, in which the agency requested additional data to meet the new guidelines.

Pfizer decided to spin out dalbavancin into new company Durata, which was backed by venture investors Domain Associates LLC, New Leaf Venture Partners, Aisling Capital, Sofinnova Ventures and Canaan. Durata went public via an initial public offering in 2012 while conducting the DISCOVER-1 phase III trial designed to compare the efficacy of dalbavancin to vancomycin. (See BioWorld Today, Dec. 23, 2009, April 20, 2011, and July 20, 2012.)

The NDA package included the full dataset from Durata's development program, including positive results from the two phase III trials – DISCOVER 1 and DISCOVER 2, both of which were conducted under a special protocol assessment – and data from the earlier noninferiority study. (See BioWorld Today, Sept. 30, 2013.)

In 2012, dalbavancin picked up the QIDP designation. Included in FDASIA's Generating Antibiotics Incentives Now provision to boost work on antibacterial and antifungal drugs targeting life-threatening conditions, QIDP provides qualified products priority review, an expedited review process and an additional five years of marketing exclusivity.

Dalbavancin will go up against Pfizer's oxazolidinone drug Zyvox (linezolid), Cubist Pharmaceuticals Inc.'s lipopeptide antibiotic Cubicin (daptomycin) and possibly Cubist's Sivextro (tedizolid), which has a June 20, 2014, PDUFA date and recently received a thumbs-up at an FDA advisory meeting for use in ABSSSIs. Sivextro, a once-daily oxazolidinone, originally was developed by Trius Therapeutics Inc., acquired by Cubist last year. (See BioWorld Today, Aug. 1, 2013.)

Durata has cited a number of advantages for dalbavancin, including the drug's broad activity against gram-positive bacteria, limited drug-drug interaction issues and a simpler administration in the form of once-weekly intravenous dosing.

Despite the need for new antibiotics, there's no guarantee of a successful launch. Jefferies analyst Eun K. Yang pointed out in a mid-May research note that while Cubicin was fairly successful when it first entered the market, other products have fared less well, pointing specifically to Vibativ (telavancin, Theravance Inc.), Teflaro (ceftaroline fosamil, Forest Laboratories Inc.) and Dificid (fidaxomicin, Cubist), all of which have yielded less than $100 million in sales two to three years from launch.

RBC Capital Markets analyst Adnan Butt sounded slightly more optimistic in a research note earlier this month. Durata, he wrote, "has plans to launch Dalvance expeditiously and has identified the right sales people, regions and targeted institutions to maximize the roll out, where the ramp remains a question mark in most investors' minds."

The company has said it plans to hire about 140 customer-facing professionals, including 100 sales people, 10 medical science liaisons, 10 regional directors and the rest covering reimbursement and hospital discharges.

Butt is forecasting third quarter sales of $5 million and fourth quarter sales of $13 million.

Outside the U.S., Durata is expected to seek a commercialization partner. Dalbavancin currently is under review in the European Union.