Analysis of Pooled Phase 3 Safety Data for Delafloxacin in Acute Bacterial Skin and Skin Structure Infections

Updated Review on Clinically-Relevant Properties of Delafloxacin

The extensive use of fluoroquinolones has been consequently accompanied by the emergence of bacterial resistance, which triggers the necessity to discover new compounds. Delafloxacin is a brand-new anionic non-zwitterionic fluoroquinolone with some structural particularities that give it attractive proprieties: high activity under acidic conditions, greater in vitro activity against Gram-positive bacteria-even those showing resistance to currently-used fluoroquinolones-and nearly equivalent affinity for both type-II topoisomerases (i.e., DNA gyrase and topoisomerase IV). During phases II and III clinical trials, delafloxacin showed non-inferiority compared to standard-of-care therapy in the treatment of acute bacterial skin and skin structure infections and community-acquired bacterial pneumonia, which resulted in its approval in 2017 by the Food and Drug Administration for indications. Thanks to its overall good tolerance, its broad-spectrum in vitro activity, and its ease of use, it could represent a promising molecule for the treatment of bacterial infections.

Overview of Side-Effects of Antibacterial Fluoroquinolones: New Drugs versus Old Drugs, a Step Forward in the Safety Profile?

Antibacterial fluoroquinolones (FQs) are frequently used in treating infections. However, the value of FQs is debatable due to their association with severe adverse effects (AEs). The Food and Drug Administration (FDA) issued safety warnings concerning their side-effects in 2008, followed by the European Medicine Agency (EMA) and regulatory authorities from other countries. Severe AEs associated with some FQs have been reported, leading to their withdrawal from the market. New systemic FQs have been recently approved. The FDA and EMA approved delafloxacin. Additionally, lascufloxacin, levonadifloxacin, nemonoxacin, sitafloxacin, and zabofloxacin were approved in their origin countries. The relevant AEs of FQs and their mechanisms of occurrence have been approached. New systemic FQs present potent antibacterial activity against many resistant bacteria (including resistance to FQs). Generally, in clinical studies, the new FQs were well-tolerated with mild or moderate AEs. All the new FQs approved in the origin countries require more clinical studies to meet FDA or EMA requirements. Post-marketing surveillance will confirm or infirm the known safety profile of these new antibacterial drugs. The main AEs of the FQs class were addressed, highlighting the existing data for the recently approved ones. In addition, the general management of AEs when they occur and the rational use and caution of modern FQs were outlined.

The efficacy and adverse events of delafloxacin in the treatment of acute bacterial infections: A systematic review and meta-analysis of randomized controlled trials

Background: This study aims to assess the clinical efficacy and adverse events of delafloxacin for the treatment of acute bacterial infections in adult patients through meta-analysis.

Methods: The PubMed, Embase, Cochrane library, Web of Science, and Clinical trails databases were searched up to 26 March 2022. Only randomized controlled trials (RCTs) that evaluated delafloxacin and comparator antibiotics for treating acute bacterial infections in adult patients were included. The clinical cure rate and microbiological eradication rate at the posttreatment evaluation, while the secondary outcomes included the risk of adverse events (AEs).

Results: In total, six randomized controlled trials (RCTs) involving 3,019 patients with acute bacterial infection were included. There were no significant differences in the clinical cure rate between delafloxacin and comparators (OR = 1.06%, 95% CI = 0.89–1.26, I² = 0%). Overall, the results showed that delafloxacin had a microbiological eradication rate (documented and presumed) similar to the comparators (OR = 1.33%, 95% CI = 0.94–1.88, I² = 0%) in the pooled analysis of the six studies. Any treatment-emergent adverse events (TEAEs) did not show significant differences between delafloxacin and the comparators (OR = 0.93%, 95% CI = 0.80–1.08, I² = 75%). Serious adverse events (SAEs) did not differ between the delafloxacin and comparators (OR = 0.94%, 95% CI = 0.67–1.32, I² = 0%). The results of gastrointestinal disorders were (OR = 1.26%, 95% CI = 1.01–1.56, I² = 89%), and nausea, vomiting, and diarrhea were (OR = 0.77%, 95% CI = 0.45–1.34, I² = 79%), (OR = 1.00%, 95% CI = 0.74–1.36, I² = 72%), and (OR = 2.10%, 95% CI = 1.70–2.96, I² = 0%), respectively. The results showed that there was no significant difference in the incidence of nausea and vomiting between delafloxacin and the comparator, but the incidence of diarrhea was higher. The analysis of neurological disorders indicated that the incidence of nervous system disorders was lower in the delafloxacin group (OR = 0.71%, 95% CI = 0.50–1.01, I² = 52%).

Conclusion: The clinical efficacy, microbiological eradication rate and the incidence of AEs of delafloxacin in the treatment of acute bacterial infections were similar to those of the comparators, as an alternative therapeutic agent.

New drugs for methicillin-resistant Staphylococcus aureus skin and soft tissue infections

PURPOSE OF REVIEW

Staphylococcus aureus is a pathogen incriminated in skin and soft tissue infections (SSTIs), with methicillin-resistant S. aureus (MRSA) becoming the predominant cause and representing a significant burden to the healthcare system. The last updated Infectious Diseases Society of America (IDSA) guidelines concerning MRSA infections and SSTIs management were published in 2011 and 2014, respectively. The UK updated guidelines for MRSA infection treatment were published in 2021. Older treatment options may be associated with toxicity and require frequent dosing. There is a paucity of recent reviews on the armamentarium of new agents for MRSA SSTIs treatment.

RECENT FINDINGS

Since 2005, several new antibiotics received a fast-track approval by the Food and Drug Administration (FDA) for SSTI treatment. These drugs include delafloxacin, omadacycline, tedizolid, ceftaroline, dalbavancin, oritavancin and telavancin. In this manuscript, we will review the data that led to these new drugs approval and discuss their advantages and disadvantages in MRSA SSTIs management.

SUMMARY

MRSA is a major cause of SSTIs. Several novel therapies covering MRSA were FDA-approved for SSTIs. However, the current IDSA guidelines for MRSA infection and SSTIs as well as the recently published UK guidelines on MRSA treatment only consider these drugs as alternative choices or do not mention them at all.

Current international and national guidelines for managing skin and soft tissue infections

PURPOSE OF REVIEW

Skin and soft tissue infections account for a significant percentage of both community and nosocomial infections. Several nosological entities are included in this concept. However, there is a very scarce body of doctrine for their treatment based on randomised trials. Therefore, we considered it necessary to review current treatment guidelines to bring new recommendations and improvements to our colleagues. In this review of recent literature, we identified updated guidelines in this area by searching the databases PubMed, evidence-based medicine online, York University reviewers group, Cochrane, MBE-Trip and Sumsearch using the terms: soft tissue infection, therapy, guideline.

RECENT FINDINGS

Developments focus on using new antimicrobials and on the prescription of shorter antibiotic treatment courses.

SUMMARY

With the development of new drugs and the current evidence of their use, there is a need to refine the appropriate drug's decision-making. Drugs with a long half-life, which allows weekly administration, can reduce hospital admission and length of stay with fewer healthcare resources. Shorter courses of antibiotics are recommended. The role of stewardship programmes will continue to expand. The surgical indication and its value are evident in many patients. Therefore, management should rely on a collaborative group with experience in this disease.

Current and future options for treating complicated skin and soft tissue infections: focus on fluoroquinolones and long-acting lipoglycopeptide antibiotics

Bacterial skin and soft tissue infections are among the most common bacterial infections and constitute a major burden for patients and healthcare systems. Care is complicated by the variety of potential pathogens, some with resistance to previously effective antimicrobial agents, the wide spectrum of clinical presentations and the risk of progression to life-threatening forms. More-efficient care pathways are needed that can reduce hospital admissions and length of stay, while maintaining a high quality of care and adhering to antimicrobial stewardship principles. Several agents approved recently for treating acute bacterial skin and skin structure infections have characteristics that meet these requirements. We address the clinical and pharmacological characteristics of the fourth-generation fluoroquinolone delafloxacin, and the long-acting lipoglycopeptide agents dalbavancin and oritavancin.

Potential role of new-generation antibiotics in acute bacterial skin and skin structure infections

PURPOSE OF REVIEW

To summarize the available results of primary analyses from high-quality randomized studies of either recently approved or possible future agents for the treatment of acute bacterial skin and skin structure infections (ABSSSI).

RECENT FINDINGS

In the last 2 decades, several novel agents have been approved for the treatment of ABSSSI, that are also active against methicillin-resistant Staphylococcus aureus (MRSA). In addition to already available agents, further molecules are in clinical development that could become available for treating ABSSSI in the forthcoming future.

SUMMARY

The current and future availability of several new-generation antibiotics will allow to modulate therapeutic choices not only on efficacy but also on other relevant factors such as the combination of the drug safety profile and the comorbidities of any given patient, the expected adherence to outpatient therapy, and the possibilities of early discharge or avoiding hospitalization by means of oral formulations, early switch from intravenous to oral therapy, or single-dose administration of long-acting intravenous agents. With the advent of new-generation antibiotics, all these factors are becoming increasingly essential for tailoring treatment to individual patients in line with the principles of personalized medicine, and for optimizing the use of healthcare resources.

Delafloxacin as a treatment option for community-acquired pneumonia infection

Community-acquired pneumonia (CAP) is a leading cause of morbidity and mortality in adults. Bacterial pathogens are recognized to be frequent causative agents, which makes antibacterial treatment crucial for the evolution of these patients. There are several antimicrobial options available in daily practice. However, bacterial resistance is a problem. The chemical, pharmacokinetic, pharmacodynamics, and safety characteristics of delafloxacin, a fluoroquinolone, are discussed. The data from one phase 3 clinical trial evaluating the use of delafloxacin in adults with community-acquired pneumonia is also discussed, along with findings from other meaningful studies. In vitro data have shown that delafloxacin has broad spectrum activity. Results from phase 2 and phase 3 studies have demonstrated that delafloxacin use is safe. International guidelines have recommended respiratory fluoroquinolones as second option for non-severe cases and must be considered in very severe patients not improving to a betalactam/macrolide combination. Delafloxacin was compared to moxifloxacin in the phase 3 community-acquired pneumonia trial. Serious and life-long adverse events due to fluoroquinolones use have been recently reported. Delafloxacin may possibly replace currently available fluoroquinolones, particularly in the treatment of resistant pathogens, such as ciprofloxacin-resistant P. aeruginosa isolates when other drugs are inefficient.

Delafloxacin: A Review in Acute Bacterial Skin and Skin Structure Infections

The global spread of antibacterial-resistant strains, especially methicillin-resistant Staphylococcus aureus (MRSA) for acute bacterial skin and skin structure infections (ABSSSIs), has driven the need for novel antibacterials. Delafloxacin [Quofenix™ (EU); Baxdela^® (USA)], a new fluoroquinolone (FQ), has a unique chemical structure that enhances its antibacterial activity in acidic environments such as occurs in ABSSSIs (including S. aureus infections). Delafloxacin (intravenous and oral formulations) is approved in several countries for the treatment of adults with ABSSSIs (featured indication). In intent-to-treat analyses in pivotal phase 3 trials in adults with ABSSSIs, including those with comorbid disease, intravenous delafloxacin monotherapy (± oral switch after six doses) twice daily was noninferior to intravenous vancomycin + aztreonam for primary endpoints, as specified by the FDA (objective response rate at 48–78 h after initiation of therapy) and the EMA [investigator-assessed clinical cure rate at the follow-up visit at day 14 (± 1 day)]. Delafloxacin was generally well tolerated, with most treatment-related adverse events mild to moderate in severity and few patients discontinuing treatment because of these events. Relative to vancomycin + aztreonam (a non-FQ regimen), delafloxacin treatment was not associated with an increased risk of FQ-associated AEs of special interest. Given its unique chemical structure that confers novel properties relative to other FQ and its broad spectrum of activity against common clinically relevant Gram-positive pathogens, including against MRSA strains (± FQ-resistance mutations), and Gram-negative pathogens, intravenous delafloxacin (± oral switch) provides a novel emerging option for the treatment of adult patients with ABSSSIs.

A Phase 3 Study to Compare Delafloxacin With Moxifloxacin for the Treatment of Adults With Community-Acquired Bacterial Pneumonia (DEFINE-CABP)

BACKGROUND

The clinical and economic burden of community-acquired bacterial pneumonia (CABP) is significant and is anticipated to increase as the population ages and pathogens become more resistant. Delafloxacin is a fluoroquinolone antibiotic approved in the United States for the treatment of adults with acute bacterial skin and skin structure infections. Delafloxacin's shape and charge profile uniquely impact its spectrum of activity and side effect profile. This phase 3 study compared the efficacy and safety of delafloxacin with moxifloxacin for the treatment of CABP.

METHODS

A randomized, double-blind, comparator-controlled, multicenter, global phase 3 study compared the efficacy and safety of delafloxacin 300 mg twice daily or moxifloxacin 400 mg once daily in adults with CABP. The primary end point was early clinical response (ECR), defined as improvement at 96 (±24) hours after the first dose of study drug. Clinical response at test of cure (TOC) and microbiologic response were also assessed.

RESULTS

In the intent-to-treat analysis population (ITT), ECR rates were 88.9% in the delafloxacin group and 89.0% in the moxifloxacin group. Noninferiority of delafloxacin compared with moxifloxacin was demonstrated. At TOC in the ITT population, the success rates were similar between groups. Treatment-emergent adverse events that were considered at least possibly related to the study drug occurred in 65 subjects (15.2%) in the delafloxacin group and 54 (12.6%) in the moxifloxacin group.

CONCLUSIONS

Intravenous/oral delafloxacin monotherapy is effective and well tolerated in the treatment of adults with CABP, providing coverage for Gram-positive, Gram-negative, and atypical pathogens.

CLINICALTRIALSGOV IDENTIFIER

NCT03534622.

Acute bacterial skin and soft tissue infections: new drugs in ID armamentarium

Acute bacterial skin and soft tissue infections (SSTI) are among the most common reasons for hospitalization of adults in the USA today. Cellulitis or SSTI can cause significant morbidity and mortality. The 2014 IDSA guideline update for the management of skin and soft tissue infections classified skin infections as purulent cellulitis (causative pathogen - Staphylococcus aureus including MRSA) and nonpurulent cellulitis (causative pathogens include Streptococcus). Understanding the key difference and categorization will allow a physician to determine the appropriate treatment approach and antibiotic choice. In recent years, there have been several new antibiotics which received fast track approval by FDA as a Qualified Infectious Disease Product (QIDP) for the indication of SSTI. They Include Ceftaroline (Teflaro), Dalbavancin (Dalvance), Oritavancin (orbativ), Tedizolid (Sevixtro), Delafloxacin (Baxdela) and Omadacycline (Nuzyra). This article will briefly review each of these new antibiotics and summarize their roles in avoiding hospital admissions and reducing the duration of stay in patients with SSTI.

Quinolone Allergy

Quinolones are the second most common antibiotic class associated with drug-induced allergic reactions, but data on quinolone allergy are scarce. This review article discusses the available evidence on quinolone allergy, including prevalence, risk factors, diagnosis, clinical manifestations, cross-reactivity, and management of allergic reactions. Although the incidence of quinolone allergy is still lower than beta-lactams, it has been increasingly reported in recent decades, most likely from its expanded use and the introduction of moxifloxacin. Thorough patient history remains essential in the evaluation of quinolone allergy. Many diagnostic tools have been investigated, but skin tests can yield false-positive results and in vitro tests have not been validated. The drug provocation test is considered the test of choice to confirm a quinolone allergy but is not without risk. Evidence regarding cross-reactivity among the quinolones is limited and conflicting. Quinolone allergy can be manifested either as an immediate or delayed reaction, but is not uniform across the class, with moxifloxacin posing the highest risk of anaphylaxis. Quinolone should be discontinued when an allergic reaction occurs and avoided in future scenarios, but desensitization may be warranted if no alternatives are available.