- The Food and Drug Administration on Monday approved a new antibiotic for serious skin infections, adding another treatment option to push back against the growing threat of antimicrobial-resistant pathogens like MRSA.
- Melinta Therapeutics' Baxdela (delafloxacin) is indicated for treatment of adults with acute bacterial skin and skin structure infections (ABSSSI) caused by susceptible bacteria, the privately held biotech said in a statement announcing the approval.
- Baxdela, part of a class of antibiotics called fluoroquinolones, will be available in both intravenous and oral formulations — a flexibility Melinta believes will help in the selection of optimal treatment for ABSSSI patients, who often have other underlying medical conditions.
The FDA approval marks a major milestone in Melinta's long road developing Baxdela, which survived a 2013 reorganization that transformed Rib-X Pharmaceuticals into Melinta.
Baxdela's approval was supported by two Phase 3 studies measuring the antibiotic against the standard-of-care combination of vancomycin and aztreonam in ABSSSI patients. The first of the two trials read out in early 2015, meeting its primary endpoint for reducing lesion erythema at the 48 to 72 hour time point. Results from a confirmatory study in May 2016 showed statistical non-inferiority to vancomycin plus aztreonam.
Baxdela is active against both gram-positive and gram-negative pathogens such as methicillin-resistant Staphylococcus aureus (MRSA).
As a fluoroquinolone, though, Baxdela will carry a boxed warning of the risk of tendinitis and tendon rupture, peripheral neuropathy and central nervous system effects — disabling and serious adverse reactions that have occurred together in association with fluoroquinolone use.
In July of 2016, the FDA updated warning labels for the entire antibiotic class to caution against this risk. For specific conditions such as acute bacterial sinusitis, acute exacerbation of chronic bronchitis and uncomplicated urinary tract infections, the regulator judged the risks of fluoroquinolone use to outweigh the benefits.
Overall, development of new antibiotics has slowed as fewer pharmas and large companies seeking to enter the space. Many of the antibiotics currently on market (such as vancomycin) are generic and cheap. New antibiotics could see uptake limited by cost or by rationing, as physicians and hospitals try to slow the development of resistance.
Commercial challenges and low rates of return on investment have discouraged large R&D investments in the space, with some exceptions.
Pfizer, for example, bolstered its anti-infectives presence with a $1.6 billion deal to buy AstraZeneca's marketed portfolio in August 2016, and anti-infectives are one of Alleran's six core areas of R&D development.
Elsewhere, though, it is mostly smaller biotechs such as Zavante Therapeutics, Cempra Inc. and Tetraphase Pharmaceuticals or academic labs that are moving candidates through development.