Safety and efficacy of omadacycline by BMI categories and diabetes history in two Phase III randomized studies of patients with acute bacterial skin and skin structure infections

Omadacycline for the treatment of skin and soft tissue infections

PURPOSE OF REVIEW

To evaluate the current evidence on the use of omadacycline for the treatment of skin and soft tissue infections (SSTIs).

RECENT FINDINGS

This narrative review examines the available data on the pharmacology, clinical efficacy, safety profile, and comparative effectiveness of omadacycline in treating SSTIs, with a focus on its potential role in everyday clinical practice.

SUMMARY

Omadacycline is a viable option for outpatient therapy and early discharge in patients with SSTIs, particularly in frail populations and those undergoing chronic polypharmacotherapy. Emerging real-world evidence highlights its potential utility beyond approved indications, particularly for infections caused by multidrug-resistant microorganisms where treatment options are limited. However, further studies are needed to confirm its role in contexts beyond its current approvals.

New Perspectives on Antimicrobial Agents: Omadacycline for community-acquired pneumonia, skin and soft tissue infections, and nontuberculous mycobacteria (focus on M. abscessus)

Omadacycline is a novel antimicrobial belonging to the tetracycline class. It has the ability to evade both efflux and ribosomal methylation types of resistance and therefore has an expanded spectrum compared to other tetracycline agents. Omadacycline is active against a number of multidrug-resistant bacteria, including macrolide and doxycycline-resistant Streptococcus pneumoniae, methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus, and several enteric gram-negative bacilli. It also has activity against many nontuberculous mycobacterium (NTM) species. It is available both orally and intravenously, which allows for feasible switch therapy. This review will assess the antimicrobial activity, pharmacology, safety, and clinical efficacy of omadacycline and present the opinions of the authors on where to position omadacycline for clinical practice.

Intravenous Versus Oral Omadacycline or Linezolid for Acute Bacterial Skin and Skin Infections: A post hoc Analysis of the OASIS Trials

INTRODUCTION

Appropriate oral antibiotic therapy for the treatment of acute bacterial skin and skin structure infections (ABSSSI) is a challenge, as current oral treatment guidelines do not fully cover the most common skin pathogens. Both linezolid and omadacycline are available as intravenous or bioequivalent oral formulations.

MATERIALS AND METHODS

This post hoc analysis of the OASIS-1 (ClinicalTrials.gov identifier NCT02378480) and OASIS-2 (ClinicalTrials.gov identifier NCT02877927) phase 3 trials assessed safety and clinical efficacy of intravenous (IV)-start versus oral (PO)-start therapy in patients treated with omadacycline or linezolid for ABSSSI. In OASIS-1, patients were randomized to IV omadacycline or linezolid, with optional switch to oral therapy, while patients in OASIS-2 received oral omadacycline or linezolid. Treatment was provided for 7-14 days in both studies. The primary endpoint was an early clinical response (ECR) at 48 to 72 h, defined as survival and ≥ 20% reduction in lesion size, without rescue antibacterial therapy.

RESULTS

A total of 645 IV-start inpatients and 735 PO-start outpatients were assessed. Median age was 47 years for the IV-start group and 44 years for the PO-start group. Most patients had solely gram-positive infections (97% in each group; ECR [85.2% IV-start and 85.0% PO-start]), and the incidence of treatment-emergent adverse events (AEs) was similar between the groups. The most frequent AEs observed were nausea (11.2% [IV-start] versus 18.9% [PO-start]) and subcutaneous abscess (5.6% [IV-start] versus 1.9% [PO-start]). Discontinuation due to AEs was infrequent in both groups (2% [IV-start] versus 1.2% [PO-start]).

CONCLUSION

Oral therapy is equally efficacious to IV therapy when omadacycline or linezolid is used to treat ABSSSIs. These data strengthen the evidence for oral omadacycline as a therapeutic option for ABSSSI, particularly for patients who have experienced treatment failure because of the limitations of other therapies.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT02378480 and NCT02877927.

Independent association of general and central adiposity with risk of gallstone disease: observational and genetic analyses

Background

General obesity is a well-established risk factor for gallstone disease (GSD), but whether central obesity contributes additional independent risk remains controversial. We aimed to comprehensively clarify the effect of body fat distribution on GSD.

Methods

We first investigated the observational association of central adiposity, characterized by waist-to-hip ratio (WHR), with GSD risk using data from UK Biobank (N=472,050). We then explored the genetic relationship using summary statistics from the largest genome-wide association study of GSD (ncase=43,639, ncontrol=506,798) as well as WHR, with and without adjusting for body mass index (BMI) (WHR: n=697,734; WHRadjBMI: n=694,649).

Results

Observational analysis demonstrated an increased risk of GSD with one unit increase in WHR (HR=1.18, 95%CI=1.14-1.21). A positive WHR-GSD genetic correlation (r g =0.41, P=1.42×10-52) was observed, driven by yet independent of BMI (WHRadjBMI: r g =0.19, P=6.89×10-16). Cross-trait meta-analysis identified four novel pleiotropic loci underlying WHR and GSD with biological mechanisms outside of BMI. Mendelian randomization confirmed a robust WHR-GSD causal relationship (OR=1.50, 95%CI=1.35-1.65) which attenuated yet remained significant after adjusting for BMI (OR=1.17, 95%CI=1.09-1.26). Furthermore, observational analysis confirmed a positive association between general obesity and GSD, corroborated by a shared genetic basis (r g =0.40, P=2.16×10-43), multiple novel pleiotropic loci (N=11) and a causal relationship (OR=1.67, 95%CI=1.56-1.78).

Conclusion

Both observational and genetic analyses consistently provide evidence on an association of central obesity with an increased risk of GSD, independent of general obesity. Our work highlights the need of considering both general and central obesity in the clinical management of GSD.

A sex- and site-specific relationship between body mass index and osteoarthritis: evidence from observational and genetic analyses

OBJECTIVE

We primarily aimed to investigate whether there are phenotypic and genetic links underlying body mass index (BMI) and overall osteoarthritis (OA). We then intended to explore whether the relationships differ across sexes and sites.

METHOD

We first evaluated the phenotypic association between BMI and overall OA using data from the UK Biobank. We then investigated the genetic relationship leveraging summary statistics of the hitherto largest genome-wide association studies performed for BMI and overall OA. Finally, we repeated all analyses in a sex- (female, male) and site- (knee, hip, spine) specific manner.

RESULTS

Observational analysis suggested an increased hazard of diagnosed OA per 5 kg/m² increment in BMI (hazard ratio = 1.38, 95% confidence interval (CI) = 1.37-1.39). A positive overall genetic correlation was observed for BMI and OA (r_g = 0.43, P = 4.72 × 10^-133), corroborated by 11 significant local signals. Cross-trait meta-analysis identified 34 pleiotropic loci shared between BMI and OA, of which seven were novel. Transcriptome-wide association study revealed 29 shared gene-tissue pairs, targeting nervous, digestive, and exo/endocrine systems. Mendelian randomization demonstrated a robust BMI-OA causal relationship (odds ratio = 1.47, 95% CI = 1.42-1.52). A similar pattern of effects was observed in sex- and site-specific analyses, with BMI affecting OA comparably in both sexes and most strongly in the knee.

CONCLUSION

Our work demonstrates an intrinsic relationship underlying BMI and overall OA, reflected by a pronounced phenotypic association, significant biological pleiotropy, and a putative causal link. Stratified analysis further reveals that the effects are distinct across sites and comparable across sexes.

Omadacycline in treating community-based infections: a review and expert perspective

INTRODUCTION

Omadacycline is approved for the treatment of community-acquired bacterial pneumonia (CABP) and acute bacterial skin and soft tissue infection (ABSSSI). The integration of newer agents into clinical use involves understanding the nuances of clinical decision-making. This review will provide an in-depth focus on omadacycline in clinical practice.

AREAS COVERED

Literature review of omadacycline utilizing PubMed was performed to provide a comprehensive evaluation of omadacycline pharmacology, microbiology, registrational Phase 3 clinical trials, and post-marketing clinical studies. In addition, the immunomodulatory and other attributes of tetracycline class of antibiotics, of which omadacycline is a member, are reviewed, introducing the concept of antibiotic selection with attention to the bacterial pathogen and human host relationship.

EXPERT OPINION

Omadacycline builds upon the favorable attributes of tetracycline antibiotics and provides very reliable empiric coverage for both Staphylococcus aureus and Streptococcus spp. Clinicians require a more robust understanding of antibiotics, including omadacycline, in order to optimize patient outcomes, streamline care, and reduce medical costs.

Comprehensive guidance for antibiotic dosing in obese adults: 2022 update

Drug dosing in obese patients continues to be challenging due to a lack of high-quality evidence to guide dosing recommendations. We first published guidance for antibiotic dosing in obese adults in 2017, in which we critically reviewed articles identified from a broad search strategy to develop dosing recommendations for 35 antimicrobials. In this updated narrative review, we searched Pubmed, Web of Science, and the Cochrane Library using Medical Subject Headings including anti-infectives, specific generic antimicrobial names, obese, pharmacokinetics, and others. We reviewed 393 articles, cross-referenced select cited references, and when applicable, referenced drug databases, package inserts, and clinical trial data to update dosing recommendations for 41 antimicrobials. Most included articles were pharmacokinetic studies, other less frequently included articles were clinical studies (mostly small, retrospective), case reports, and very rarely, guidelines. Pharmacokinetic changes are frequently reported, can be variable, and sometimes conflicting in this population, and do not always translate to a documented difference in clinical outcomes, yet are used to inform dosing strategies. Extended infusions, high doses, and therapeutic drug monitoring remain important strategies to optimize dosing in this population. Additional studies are needed to clinically validate proposed dosing strategies, clarify optimal body size descriptors, dosing weight scalars, and estimation method of renal function in obese patients.

Insufficient Representation of Patients With Obesity in Randomized Controlled Trials Evaluating the Efficacy and Safety of Antimicrobials for Treatment of Skin and Skin Structure Infections: A Scoping Review

Persons with obesity (PwO) represent approximately 50% of acute bacterial skin and skin structure infections (ABSSSIs) in the United States (US). There are currently insufficient data in PwO for drugs used for ABSSSIs. We conducted a scoping review of randomized controlled trials (RCTs) published between 2000 and 2022 to describe how frequently body size measures were reported. Weight and/or body mass index (BMI) were recorded in approximately 50% of the 69 RCTs. The average weights or BMIs were lower than US averages for most RCTs reporting data. None evaluated the impact of body size on outcomes in the original publication. Only 30% of newly approved drugs mention PwO representation in the prescribing information. More representative recruitment of PwO into RCTs is needed to help clinicians evaluate efficacy in these patients. We suggest that the Food and Drug Administration require companies to submit plans to ensure adequate PwO inclusion and that authors of RCTs report subgroup results based on body size.

Re-establishing the utility of tetracycline-class antibiotics for current challenges with antibiotic resistance

The progressive increase in antibiotic resistance in recent decades calls for urgent development of new antibiotics and antibiotic stewardship programs to help select appropriate treatments with the goal of minimising further emergence of resistance and to optimise clinical outcomes. Three new tetracycline-class antibiotics, eravacycline, omadacycline, and tigecycline, have been approved within the past 15 years, and represent a new era in the use of tetracyclines. These drugs overcome the two main mechanisms of acquired tetracycline-class resistance and exhibit a broad spectrum of in vitro activity against gram-positive, gram-negative, anaerobic, and atypical pathogens, including many drug-resistant strains. We provide an overview of the three generations of tetracycline-class drugs, focussing on the efficacy, safety, and clinical utility of these three new third-generation tetracycline-class drugs. We also consider various scenarios of unmet clinical needs where patients might benefit from re-engagement with tetracycline-class antibiotics including outpatient treatment options, patients with known β-lactam antibiotic allergy, reducing the risk of Clostridioides difficile infection, and their potential as monotherapy in polymicrobial infections while minimising the risk of any potential drug-drug interaction. KEY MESSAGESThe long-standing safety profile and broad spectrum of activity of tetracycline-class antibiotics made them a popular choice for treatment of various bacterial infections; unfortunately, antimicrobial resistance has limited the utility of the early-generation tetracycline agents.The latest generation of tetracycline-class antibiotics, including eravacycline, tigecycline, and omadacycline, overcomes the most common acquired tetracycline resistance mechanisms.Based on in vitro characteristics and clinical data, these newer tetracycline agents provide an effective antibiotic option in the treatment of approved indications in patients with unmet clinical needs - including patients with severe penicillin allergy, with renal or hepatic insufficiency, recent Clostridioides difficile infection, or polymicrobial infections, and those at risk of drug-drug interactions.

Omadacycline Oral Dosing and Pharmacokinetics in Community-Acquired Bacterial Pneumonia and Acute Bacterial Skin and Skin Structure Infection

Omadacycline, a first-in-class aminomethylcycline antibiotic, is approved in the USA as intravenous (IV) and/or oral therapy for treatment of adults with community-acquired bacterial pneumonia (CABP) or acute bacterial skin and skin structure infections (ABSSSI). Phase 1 and 3 studies indicate that omadacycline dose adjustments are not required for any patient group based on age, sex, race, weight, renal impairment, end-stage renal disease, or hepatic impairment. Equivalency of exposure has also been demonstrated for 300 mg oral and 100 mg IV doses. Using an oral loading-dose regimen results in drug exposures exceeding established efficacy targets against the most common CABP and ABSSSI pathogens by Day 2 of treatment, and omadacycline has demonstrated clinical efficacy and is well tolerated. The oral-only dosing regimens provide the potential for treatment of CABP and ABSSSI either within a hospital setting or in the community, which could support earlier hospital discharge and reduced treatment costs.

OUP accepted manuscript

Objectives

We assessed the plasma and soft-tissue pharmacokinetic exposure of omadacycline in infected patients with diabetic foot infection (DFI) and healthy volunteers using in vivo microdialysis.

Methods

Eight patients and six healthy volunteers were enrolled and received an omadacycline IV loading dose (200 mg) followed by two oral doses (300 mg) every 24 h. Microdialysis catheters were placed in the soft tissue near the infected diabetic foot wound (patients) or thigh (healthy volunteers). Plasma and dialysate fluid samples were collected, starting immediately prior to the third dose and continued for 24 h post-dose. Protein binding was determined by ultracentrifugation.

Results

The mean ± SD omadacycline pharmacokinetic parameters in plasma for infected patients and healthy volunteers were: C_max, 0.57 ± 0.15 and 1.14 ± 0.26 mg/L; t_½, 16.19 ± 5.06 and 25.34 ± 12.92 h; and total omadacycline AUC_0–24, 6.27 ± 1.38 and 14.06 ± 3.40 mg·h/L, respectively. The omadacycline mean plasma free fraction was 0.21 and 0.20 for patients and healthy volunteers, corresponding to free plasma AUC_0–24 of 1.13 ± 0.37 and 2.78 ± 0.55 mg·h/L, respectively. Omadacycline tissue AUC_0–24 was 0.82 ± 0.38 and 1.37 ± 0.48 mg·h/L for patients and volunteers, respectively.

Conclusions

The present study describes the plasma and soft-tissue exposure of omadacycline in patients with DFI and healthy volunteers. Integrating these data with the microbiological, pharmacokinetic/pharmacodynamic and clinical efficacy data is foundational to support clinical assessments of omadacycline efficacy specifically for DFI. This, coupled with the once-daily oral administration, suggests omadacycline could be an advantageous translational therapy for the hospital and outpatient setting.