The U.S. Food and Drug Administration has approved a number of new antibiotics targeting multidrug-resistant bacteria in the past 5 years, but the new drugs have not led to a substantial improvement in patient outcomes when compared with existing antibiotics, according to a recent analysis in the Annals of Internal Medicine.
The eight new antibiotics approved by the FDA between January 2010 and December 2015 were ceftaroline, fidaxomicin, bedaquiline, dalbavancin, tedizolid, oritavancin, ceftolozane/tazobactam, and ceftazidime/avibactam. Of those eight drugs, only three showed in vitro activity against the so-called ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumonia, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species). Only one drug, fidaxomicin, demonstrated in vitro activity against an urgent-threat pathogen from the Centers for Disease Control and Prevention, Clostridium difficile. Bedaquiline was the only new antibiotic specifically indicated for a disease from a multidrug-resistant pathogen, although the investigators said most of the drugs demonstrated in vitro activity against gram-positive drug-resistant pathogens.
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Importantly, the authors noted that in vitro activity does not necessarily reflect benefits on actual patient clinical outcomes, as exemplified by such drugs as tigecycline and doripenem.
The researchers found what they called “important deficiencies in the clinical trials leading to approval of these new antibiotic products.” Most pivotal trial designs were primarily noninferiority trials, and the antibiotics were not studied to evaluate whether they have substantial benefits in efficacy over what is currently available, they noted. Additionally, none of the trials evaluated direct patient outcomes as primary end points, and some drugs did not have confirmatory evidence from a second independent trial or did not have any confirmatory trials.
Researchers also examined the prices of a single dose of the new antibiotics. The prices ranged from $1,195 to $4,183 (4-14 days of ceftolozane/tazobactam for acute pyelonephritis and intra-abdominal infections) to $69,702 (24 weeks of bedaquiline) – quite a premium for antibiotics showing unclear evidence of additional benefit.
“As antibiotic innovation continues to move forward, greater attention needs to be paid to incentives for developing high-quality new products with demonstrated superiority to existing products on outcomes in patients with multidrug-resistant disease, replacing the current focus on quantity and presumed future benefits,” researchers concluded.
Read the full study in the Annals of Internal Medicine (doi: 10.7326/M16-0291).