Tigecycline: 'A Choice of Last Resort'
Posted: 10/08/2012
Tigecycline Risks
The antibacterial drug tigecycline (Tygacil®, Pfizer Inc) has been linked to an increased risk for death when used for approved (and unapproved) indications. Greater awareness of this risk is needed among infectious disease specialists.
In a pooled analysis of 13 randomized controlled trials, published June 15, 2012, in Clinical Infectious Diseases,[1] tigecycline was associated with a 0.7 percentage point absolute or 30% relative increase in mortality, translating into 1 excess death for every 143 patients treated. The effect was independent of infection type, trial design, and study size.
The authors of the report, led by Paritosh Prasad, MD, from the Critical Care Medicine Department, National Institutes of Health, Bethesda, Maryland, conclude that tigecycline "should not be used when other effective antibiotic choices are available."
In a commentary published with the study,[2] John H. Powers, MD, of the National Institute of Allergy and Infectious Diseases, advises clinicians to "carefully consider when to administer tigecycline. Unfortunately, patients and clinicians are left with little direct evidence from controlled trials in the settings where the drug is needed most."
In an interview with Medscape, Robert A. Bonomo, MD, Professor of Medicine at Louis Stokes Cleveland Veterans Affairs Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio, said, "Mounting data do suggest an increased risk for death with tigecycline, and the decision to use this drug should be made with thoughtful deliberation and caution."
"I would seek other alternatives if I could and use tigecycline as a choice of last resort. In my opinion, tigecycline is used a fair amount by clinicians in instances where they have no other option. They have to treat a multidrug-resistant infection, and they don't have a choice," he said.
A Brief History of Tigecycline
The growing problem of antibiotic-resistant organisms has made the development of new antimicrobial agents a priority. Tigecycline was designed to meet this need. A first-in-class expanded broad-spectrum glycycline antibiotic, the drug has activity against a variety of pathogens that are susceptible and resistant to other antibiotics, including methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus species, and penicillin-resistant Streptococcus pneumoniae.
The US Food and Drug Administration (FDA) granted priority review status to tigecycline in June 2005 and 6 months later approved the drug for treatment of complicated intra-abdominal infections and complicated skin and skin structure infections.[3] In 2009, tigecycline was also granted approval for community-acquired pneumonia.[4]
In clinical trials,[5,6] tigecycline has also been shown to be effective for hospital-acquired pneumonia (including ventilator-associated pneumonia), although it is not approved for these indications.
In September 2010, on the basis of reports to MedWatch, the FDA's safety information and adverse event reporting program, the FDA issued a warning and updated the drug label alerting clinicians that tigecycline was associated with an increased risk for death compared with other antibiotics [7].
As reported by Medscape Medical News (Tigecycline Linked to Increased Mortality Risk) the FDA cited a pooled analysis of 13 clinical trials in which tigecycline was used for approved and unapproved indications. In this analysis, tigecycline had an overall adjusted mortality rate of 4% vs 3% for the comparator group, a relative mortality increase of 33%. The increased risk for death was most evident in patients treated with tigecycline for hospital-acquired pneumonia, an unapproved indication, but was also seen in patients treated with tigecycline for approved indications.[7]
Troubled Tigecycline Trials?
The cause of the excess deaths observed in clinical trials is uncertain, and most were probably related to the severe infection for which tigecycline was used to treat. Dr. Bonomo believes that "there probably is more to it than meets the eye, and I really think this needs a little deeper digging to figure out what exactly is going on."
"Many times, tigecycline is used in very serious and severe infection as a last-ditch effort, a fact that is supposed to be taken account of in clinical studies. These studies are supposed to factor in for severity of illness, but that may not have been done properly in the tigecycline trials, and that could be a potential factor. The other issue is that tigecycline's activity is such that it is used against organisms that are very virulent anyway. These are 2 possible explanations for what we are seeing."
The pooled analysis published in Clinical Infectious Diseases[1] also revealed a 2.9 percentage point or 12% relative increase in noncure rates with tigecycline, which means that disease is not cured in 1 among every 34 patients treated. Dr. Bonomo said that he has used tigecycline "many times clinically, and it's been effective. It does have an important clinical role. I don't think we should throw it out, but it must be used very cautiously."
"In combination with other drugs, such as colistin, tigecycline is effective. By itself, I can't give it 100% endorsement, but as part of combination chemotherapy against some really drug-resistant pathogens, I think it may be helpful -- at least some of the data show that it is." In a study done in Pittsburgh, Pennsylvania, tigecycline was combined with a variety of agents and mortality was less than when used as monotherapy."[8]
Game-Changer Drugs on the Horizon?
The problem, Dr. Bonomo said, is that there are limited antibiotics for clinicians to choose from. "Right now," he explained, "when we generally think of tigecycline, at the same time we generally think of such drugs as colistin. We don't really have a lot of alternatives at this point in the game. That may change in the next couple of months or half-year or so, when we may see some interesting drugs become available. For example, the introduction of some of the beta-lactamase inhibitors, such as avibactam, is going to be very important."
Avibactam is a novel investigational non-beta-lactam beta-lactamase inhibitor that is being developed for possible use in combination with ceftaroline. Avibactam does not have any intrinsic antibacterial activity in its own right, but it seems to inhibit beta-lactamase enzymes that belong to molecular classes A and C. Avibactam is being evaluated in combination with ceftaroline (Teflaro®, Forest Labs) to see whether it can enhance ceftaroline's spectrum of antibacterial activity against gram-negative bacteria that produce both class A and C enzymes.[9]
Ceftaroline is an advanced-generation injectable cephalosporin antibiotic that is active against MRSA and gram-positive bacteria. It retains the activity of later-generation cephalosporins that have broad-spectrum activity against gram-negative bacteria. It is FDA-approved for the treatment of community-acquired pneumonia and complicated skin and skin structure infections.[10]
"The introduction of plazomicin, a neoglycoside, is also going to be very important in terms of gram-negative infections," Dr. Bonomo said. Plazomicin (formerly ACHN-490) is a next-generation aminoglycoside currently in early clinical development. It has enhanced activity against many multidrug resistant gram-negative bacteria and S aureus, including MRSA isolates.[11]
The Bottom Line for Clinicians
Regarding tigecycline, Dr. Bonomo said: "With what we know right now, the take-home message is to use tigecycline cautiously, only when needed; to be careful; to know the type of patient whom you're giving it to; and to know the full clinical ramifications of the treatment regimen that you are using. Right now, we have no idea why tigecycline may raise the risk for death; I don't think anybody does. I would seek other alternatives if I could, and use tigecycline as a choice of last resort," Dr. Bonomo added.
References
- Prasad P, Sun J, Danner RL, Natanson C. Excess deaths associated with tigecycline after approval based on non-inferiority trials. Clin Infect Dis. 2012;54:1699-1709. Abstract
- Powers JH. Editorial commentary: asking the right questions: morbidity, mortality, and measuring what's important in unbiased evaluations of antimicrobials. Clin Infect Dis. 2012;54:1710-1713. Abstract
- US Food and Drug Administration. NME drug and new biologic approvals in 2005. August 29, 2011.
http://www.fda.gov/Drugs/DevelopmentApprovalProcess/HowDrugsareDevelopedandApproved
/DrugandBiologicApprovalReports/ucm081676.htm Accessed September 28, 2012. - Waknine Y. FDA approvals: Afinitor and Tygacil. Medscape Medical News. April 2, 2009. http://www.medscape.com/viewarticle/590590 Accessed September 28, 2012.
- Bergallo C, Jasovich A, Teglia O, et al; 308 Study Group. Safety and efficacy of intravenous tigecycline in treatment of community-acquired pneumonia: results from a double-blind randomized phase 3 comparison study with levofloxacin. Diagn Microbiol Infect Dis. 2009;63:52-61. Abstract
- Tanaseanu C, Milutinovic S, Calistru PI, et al; 313 Study Group. Efficacy and safety of tigecycline versus levofloxacin for community-acquired pneumonia. BMC Pulm Med. 2009;9:44.
- US Food and Drug Administration. FDA Drug Safety Communication: increased risk of death with Tygacil (tigecycline) compared to other antibiotics used to treat similar infections. September 1, 2010. http://www.fda.gov/Drugs/DrugSafety/ucm224370.htm Accessed September 28, 2012.
- Qureshi ZA, Paterson DL, Potoski BA, et al. Treatment outcome of bacteremia due to KPC-producing Klebsiella pneumoniae: superiority of combination antimicrobial regimens. Antimicrob Agents Chemother. 2012;56:2108-2113. Abstract
- Cerexa, Inc. Avibactam. http://www.cerexa.com/Avibactam.aspx Accessed September 28, 2012.
- US Food and Drug Administration. FDA approves Teflaro for bacterial infections. October 29, 2010. http://www.fda.gov/newsevents/newsroom/pressannouncements/ucm231594.htm Accessed September 28, 2012.
- Achaogen, Inc. Next-generation aminoglycosides. http://www.achaogen.com/pipeline/next-generation-aminoglycosides Accessed September 28, 2012.
Medscape Infectious Diseases © 2012 WebMD, LLC
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