Clinical Burden of Chronic Obstructive Pulmonary Disease in Patients with Suboptimal Peak Inspiratory Flow.

Introduction: Many patients with chronic obstructive pulmonary disease (COPD) may derive inadequate benefit from dry powder inhalers (DPIs) because of suboptimal peak inspiratory flow (sPIF). Objectives: To assess the clinical burden of COPD by characterizing the clinical characteristics of participants with sPIF against medium-low resistance DPIs versus those with optimal PIF (oPIF) from two phase 3 clinical trials. Methods: Baseline data were collected from two randomized, controlled, phase 3 trials (NCT03095456; NCT02518139) in participants with moderate-to-severe COPD. oPIF (60 L/min) against the medium-low resistance DPIs was used as the threshold for defining the PIF subgroups (<60 L/min (sPIF) vs ≥60 L/min (oPIF)). Results: Most participants included in this analysis were White (92%) and male (63%); the mean (range) age was 65 (43-87) years. Participants with sPIF had significantly greater dyspnea than those with oPIF as measured using the modified Medical Research Council scoring (mean (95% CI): 2.1 (2.0-2.2) vs 1.6 (1.4-1.7); P < 0.001) and baseline dyspnea index (mean (95% CI): 5.1 (4.9-5.4) vs 6.1 (5.8-6.3); P < 0.001). Based on COPD Assessment Test scores, participants with sPIF had a higher COPD symptom burden than those with oPIF (mean (95% CI): 21.5 (19.7-23.3) vs 19.5 (18.6-20.4); P = 0.05). Conclusion: In these trials, participants with COPD who had sPIF against the medium-low resistance DPIs had more dyspnea and worse health status than those with oPIF. These results demonstrate that sPIF is associated with a higher clinical burden as measured by patient-reported outcomes.

Efficacy and safety of an inhaled pan-Janus kinase inhibitor, nezulcitinib, in hospitalised patients with COVID-19: results from a phase 2 clinical trial.

BACKGROUND: The inhaled lung-selective pan-Janus kinase inhibitor nezulcitinib had favourable safety and potential efficacy signals in part 1 of a phase 2 trial in patients with severe COVID-19, supporting progression to part 2. METHODS: Part 2 was a randomised, double-blind phase 2 study (NCT04402866). Hospitalised patients aged 18-80 years with confirmed symptomatic COVID-19 requiring supplemental oxygen (excluding baseline invasive mechanical ventilation) were randomised 1:1 to nebulised nezulcitinib 3 mg or placebo for up to 7 days with background standard-of-care therapy (including corticosteroids). Efficacy endpoints included respiratory failure-free (RFF) days through day 28 as the primary endpoint. Secondary endpoints included safety and change from baseline oxygen saturation (SaO2)/fraction of inspired oxygen (FiO2) ratio on day 7, and 28-day mortality rate was a prespecified exploratory endpoint. RESULTS: Between June 2020 and April 2021, 205 patients were treated (nezulcitinib, 103; placebo, 102). There was no statistically significant difference between nezulcitinib versus placebo in the primary endpoint (RFF days; median, 21.0 vs 21.0; p=0.6137) or secondary efficacy endpoints. Nezulcitinib was generally well tolerated with a favourable safety profile. CONCLUSIONS: Although the prespecified primary, secondary and exploratory efficacy endpoints, including RFF through day 28, change from baseline SaO2/FiO2 ratio on day 7, and 28-day mortality rate, were not met, nezulcitinib was generally well tolerated and had a favourable safety profile. Further studies are required to determine if treatment with nezulcitinib confers clinical benefit in specific inflammatory biomarker-defined populations of patients with COVID-19.

Efficacy of revefenacin, a long-acting muscarinic antagonist for nebulized therapy, in patients with markers of more severe COPD: a post hoc subgroup analysis.

BACKGROUND: Revefenacin, a once-daily, long-acting muscarinic antagonist delivered via standard jet nebulizer, increased trough forced expiratory volume in 1 s (FEV1) in patients with moderate to very severe chronic obstructive pulmonary disease (COPD) in prior phase 3 trials. We evaluated the efficacy of revefenacin in patients with markers of more severe COPD. METHODS: A post hoc subgroup analysis of two replicate, randomized, phase 3 trials was conducted over 12 weeks. Endpoints included least squares change from baseline in trough FEV1, St. George's Respiratory Questionnaire (SGRQ) responders, and transition dyspnea index (TDI) responders at Day 85. This analysis included patient subgroups at high risk for COPD exacerbations and compared patients who received revefenacin 175 µg and placebo: severe and very severe airflow limitation (percent predicted FEV1 30%-< 50% and < 30%), 2011 Global Initiative for Chronic Obstructive Lung Disease (GOLD) D, reversibility (≥ 12% and ≥ 200 mL increase in FEV1) to short-acting bronchodilators, concurrent use of long-acting ß agonists and/or inhaled corticosteroids, older age (> 65 and > 75 years), and comorbidity risk factors. RESULTS: Revefenacin demonstrated significant improvements in FEV1 versus placebo at Day 85 among the intention-to-treat (ITT) population and all subgroups. Additionally, there was a greater number of SGRQ and TDI responders in the ITT population and the majority of subgroups analyzed among patients who received revefenacin versus placebo. For the SGRQ responders, the odds of response (odds ratio > 2.0) were significantly greater in the revefenacin arm versus the placebo arm among the severe airflow obstruction, very severe airflow obstruction and 2011 GOLD D subgroups. For the TDI responders, the odds of response (odds ratio > 2.0) were significantly greater among the severe airflow obstruction subgroup and patients aged > 75 years. CONCLUSIONS: Revefenacin showed significantly greater improvements in FEV1 versus placebo in the ITT population and all subgroups. Furthermore, there were a greater number of SGRQ and TDI responders in the ITT population, and in the majority of patient subgroups among patients who received revefenacin versus placebo. Based on the data presented, revefenacin could be a therapeutic option among patients with markers of more severe COPD. TRIAL REGISTRATION: Clinical trials registered with www.clinicaltrials.gov (Studies 0126 [NCT02459080; prospectively registered 22 May 2015] and 0127 [NCT02512510; prospectively registered 28 July 2015]).

Safety and Efficacy of Revefenacin and Formoterol in Sequence and Combination via a Standard Jet Nebulizer in Patients with Chronic Obstructive Pulmonary Disease: A Phase 3b, Randomized, 42-Day Study.

Although no nebulized, dual mechanism, long-acting bronchodilator is currently marketed, with the approval of once-daily long-acting muscarinic antagonist (LAMA) revefenacinefenacin, it is theoretically possible to deliver a LAMA and long-acting beta2-agonist via standard jet nebulizer. The primary and secondary objectives of our study were to characterize the safety profile of revefenacin administered sequentially before or in combination with formoterol, via standard jet nebulizer in patients with moderate to very severe chronic obstructive pulmonary disease (COPD). In this randomized, double-blind, 42-day trial (NCT03573817), patients received revenacin 175 µg (n=63) or placebo (n=59), followed by formoterol 20 µg in the morning and formoterol alone in the evening formoterol 21 days via standard jet nebulizer (sequential administration). For another 21 days, revefenacin/placebo and formoterol, were administered as mixed solutions via single nebulization in the morning (combined administration), and formoterol alone in the evening. The adverse events' (AEs) incidence was higher in the placebo + formoterol arms (11%-12%) than in the revefenacin + formoterol arms (5%-8%). The most common AEs were worsening/exacerbation of COPD, cough, and dizziness. There were no serious AEs or deaths reported in any arm. The least squares mean in trough forced expiratory volume in 1 second (FEV1) versus baseline was higher in the revefenacin + formoterol arms (116-157 mL) than in the placebo + formoterol arms (35-53 mL). Revefenacin had a safety profile similar to formoterol alone when delivered sequentially or combined. Trough FEV1 was similar when revefenacin was delivered sequentially or combined with formoterol, with revefenacin providing an additional 81-104 mL improvements over formoterol alone.

Maintained therapeutic effect of revefenacin over 52 weeks in moderate to very severe Chronic Obstructive Pulmonary Disease (COPD).

BACKGROUND: Revefenacin is a long-acting muscarinic antagonist that was recently approved for the nebulized treatment of chronic obstructive pulmonary disease (COPD). Although shorter duration studies have documented the efficacy of revefenacin in COPD, longer-term efficacy has not been described. In a recent 52-week safety trial, revefenacin was well tolerated and had a favorable benefit-risk profile. Here we report exploratory efficacy and health outcomes in patients receiving revefenacin 175 µg or 88 µg daily during the 52-week trial. METHODS: In this randomized, parallel-group, 52-week trial (NCT02518139), 1055 participants with moderate to very severe COPD received revefenacin 175 µg or 88 µg in a double-blind manner, or open-label active control tiotropium. RESULTS: Over the 52-week treatment period, both doses of revefenacin, as well as tiotropium, elicited significant (all p < 0.0003) improvements from baseline in trough forced expiratory volume in 1 s (FEV1). The trough FEV1 profile (least squares mean change from baseline) for revefenacin 175 µg ranged from 52.3-124.3 mL and the trough FEV1 profile for tiotropium ranged from 79.7-112.8 mL. In subgroup comparisons, the effect of revefenacin on trough FEV1 was comparable in patients taking concomitant long-acting ß-agonists, with or without inhaled corticosteroids, with patients who were not taking these medications. There were statistically significant (p < 0.05) improvements in all measured health status outcomes (evaluated using St. George's Respiratory Questionnaire, COPD Assessment Test, Clinical COPD Questionnaire and Baseline and Transition Dyspnea Index) from 3 months onward, in all treatment arms. CONCLUSIONS: Significant sustained improvements from baseline in trough FEV1 and respiratory health outcomes were demonstrated for 175-µg revefenacin over 52 weeks, further supporting its use as a once-daily bronchodilator for the nebulized treatment of patients with COPD. TRIAL REGISTRATION: NCT02518139 ; Registered 5 August 2015.

Nebulized Versus Dry Powder Long-Acting Muscarinic Antagonist Bronchodilators in Patients With COPD and Suboptimal Peak Inspiratory Flow Rate.

BACKGROUND: Patients with chronic obstructive pulmonary disease (COPD) and suboptimal peak inspiratory flow rate (sPIFR) may not benefit optimally from dry powder inhalers (DPI) because of inadequate inspiratory flow. Nebulized bronchodilators may provide a better alternative. We compared bronchodilation with the long-acting muscarinic antagonist (LAMA) revefenacin for nebulization versus the DPI LAMA tiotropium, in patients with COPD and sPIFR (< 60 L/min against the resistance of Diskus®). METHODS: This was a randomized, double-blind, double-dummy, 28-day Phase 3b study in patients with COPD enrolled based on sPIFR. The primary endpoint was trough forced expiratory volume in 1 second (FEV1) on Day 29 for revefenacin for nebulization versus tiotropium HandiHaler® DPI. RESULTS: We enrolled 206 patients with mean (standard deviation) age, 65 (8) years; percent predicted FEV1, 37 (16)%; PIFR, 45 (12) L/min. In the intent-to-treat (ITT) population, revefenacin improved trough FEV1 from baseline; however, the difference versus tiotropium was not significant (least squares [LS] mean difference [standard error], 17.0 [22.4] mL, P=0.4461). In a prespecified analysis of patients with FEV1 < 50% predicted, revefenacin produced an LS mean difference (95% confidence interval [CI]), 49.1 (6.3-91.9) mL in trough FEV1 and 103.5 (7.7-199.3) mL in forced vital capacity versus tiotropium. Revefenacin produced >100 mL increase in FEV1 in 41.6% versus 34.4% of patients with tiotropium in ITT and 41.4% versus 25.7% of patients in FEV1 < 50% predicted populations. CONCLUSIONS: Revefenacin did not produce significant improvements in FEV1 versus tiotropium in the ITT population, but increased trough FEV1 in patients with FEV1 < 50% predicted and sPIFR. Clinical Trial Registration (www.Clinicaltrials.gov): Study 0149 (NCT03095456).

Data on the safety and tolerability of revefenacin, in patients with moderate to very severe chronic obstructive pulmonary disease.

This article contains information on the experimental design and methods on how the safety and tolerability data concerning patients with moderate to very severe chronic obstructive pulmonary disease (COPD) were obtained. This is in addition to our original research article. [1] We have also provided information on the clinical laboratory tests that were conducted. Further interpretation and discussion of the data are demonstrated in the article "Revefenacin, a Once-daily, Lung-selective, Long-acting Muscarinic Antagonist for Nebulized Therapy: Safety and Tolerability Results of a 52-week Phase 3 Trial in Moderate to Very Severe Chronic Obstructive Pulmonary Disease." [1].

Revefenacin, a once-daily, lung-selective, long-acting muscarinic antagonist for nebulized therapy: Safety and tolerability results of a 52-week phase 3 trial in moderate to very severe chronic obstructive pulmonary disease.

BACKGROUND: Prior replicate 12-week phase 3 trials demonstrated that once-daily doses of revefenacin inhalation solution at 88 µg and 175 µg produced significant bronchodilation over 24 h post dose in patients with moderate to very severe chronic obstructive pulmonary disease (COPD). The objective was to characterize the safety profile of revefenacin 88 µg and 175 µg over 52 weeks of treatment. METHODS: In this randomized, parallel-group, 52-week trial (NCT02518139), 1055 participants with moderate to very severe COPD received revefenacin 88 µg or 175 µg in a double-blind manner, or open-label active control tiotropium. RESULTS: Treatment-emergent adverse events (AEs) were comparable across all treatment groups (n [%] patients; revefenacin 88 µg, 272 [74.7%]; 175 µg, 242 [72.2%]; tiotropium, 275 [77.2%]). Numerically fewer COPD exacerbations (n [%] patients) were observed with revefenacin 175 µg (73 [21.8%]) than with 88 µg (107 [29.4%]) or tiotropium (100 [28.1%]). Serious AEs were comparable with revefenacin 88 µg (58 [15.9%] and tiotropium (58 [16.3%]), but were lower with revefenacin 175 µg (43 [12.8%]), and mortality was low. In patients using revefenacin 88 µg or tiotropium with a concurrent long-acting ß-agonist (LABA) product, the incidence of AEs was slightly higher than without concurrent LABA. LABA did not affect the incidence of AEs for patients who received revefenacin 175 µg. CONCLUSIONS: Revefenacin was generally well tolerated over 52 weeks of treatment, and had a safety profile that supports its use as a long-term once-daily bronchodilator for the nebulized treatment of COPD.

Improvements in Lung Function with Nebulized Revefenacin in the Treatment of Patients with Moderate to Very Severe COPD: Results from Two Replicate Phase III Clinical Trials.

BACKGROUND: Revefenacin, a novel, lung-selective, long-acting muscarinic antagonist, has been developed for nebulized therapy for chronic obstructive pulmonary disease (COPD). We present the results of replicate Phase III efficacy and safety studies of revefenacin in patients with moderate to very severe COPD. METHODS: In 2 double-blind, parallel-group studies, (Study 0126 and Study 0127), patients ≥ 40 years old were randomized to revefenacin 88 µg, revefenacin 175 µg or placebo administered once daily by standard jet nebulizer for 12 weeks. The primary endpoint was 24-hour trough forced expiratory volume in 1 second (FEV1) on day 85. Secondary efficacy endpoints included overall treatment effect (OTE) on trough FEV1 and peak FEV1 (0-2 hours after first dose). Safety assessments included treatment-emergent adverse events. RESULTS: At day 85, revefenacin 88 µg and 175 µg improved trough FEV1 versus placebo in Study 0126 (by 79 mL [p=0.0003] and 146 mL [p<0.0001]) and Study 0127 (by 160 mL and 147 mL; both p<0.0001). Compared with placebo, pooled data of revefenacin 88 µg and 175 µg increased OTE trough FEV1 by 115 mL and 142 mL (both p<0.001) and increased peak FEV1 by 127 mL and 129 mL (both p<0.0001). Revefenacin 175 µg demonstrated greater improvements in FEV1 in concomitant long-acting beta2-agonist patients and in more severe patients than revefenacin 88 µg. Adverse events were minor. CONCLUSION: Revefenacin, administered once daily for 12 weeks to patients with moderate to very severe COPD, demonstrated clinically significant improvements in trough FEV1 and OTE FEV1. Revefenacin was generally well tolerated with no major safety concerns.

Pharmacodynamics, pharmacokinetics and safety of revefenacin (TD-4208), a long-acting muscarinic antagonist, in patients with chronic obstructive pulmonary disease (COPD): Results of two randomized, double-blind, phase 2 studies.

BACKGROUND: Revefenacin (TD-4208) is a potent, lung-selective, long-acting muscarinic antagonist currently in development as a once-daily nebulized therapy for chronic obstructive pulmonary disease (COPD). We evaluated the pharmacodynamics (bronchodilator activity), pharmacokinetics (PK) and safety of single- and multiple-dose administrations of revefenacin in two clinical trials (Study 0059 and Study 0091) in patients with moderate to severe COPD. METHODS: In Study 0059, 32 patients were randomized to receive a single dose of revefenacin (350 or 700 µg), active control ipratropium (500 µg) or placebo inhalation solution administered via standard jet nebulizer in a double-blind, crossover fashion. In Study 0091, 59 patients were randomized to receive once-daily inhalations of revefenacin (22, 44, 88, 175, 350 or 700 µg) or placebo for 7 days in a double-blind, incomplete block, five-way crossover design. The primary efficacy endpoint was change from baseline in peak (0-6 h) forced expiratory volume in 1 s (FEV1) in Study 0059, and trough FEV1 after the final dose (Day 7) in Study 0091. In both studies, secondary endpoints included area under the FEV1-time curve (FEV1 AUC) values from time 12-24 h post dose and FEV1 AUC values from time zero to 24 h post dose. RESULTS: Revefenacin demonstrated a rapid onset and sustained duration of bronchodilator action in both studies. In Study 0059, mean peak FEV1 was significantly higher (p < 0.001) for revefenacin and ipratropium compared to placebo, with differences of 176.8 mL for 350 µg revefenacin, 162.2 mL for 700 µg revefenacin and 190.6 mL for ipratropium. In Study 0091, mean trough FEV1 on Day 7 was significantly higher (p < 0.006) for all revefenacin doses compared to placebo, with differences ranging from 53.5 mL (22 µg dose) to 114.2 mL (175 µg dose). The results for the other spirometry endpoints were consistent with the primary endpoint for each study, demonstrating that the bronchodilator effect of revefenacin lasted more than 24 h following nebulized administration. Revefenacin was rapidly absorbed and extensively metabolized, followed by a slow apparent terminal elimination and minimal accumulation with repeated dosing. In both studies, adverse events were generally mild and occurred with similar frequencies in all groups, with no indication of significant systemic anti-muscarinic activity at any dose. CONCLUSIONS: Following single or multiple nebulized-dose administration in patients with COPD, revefenacin demonstrates a rapid onset and sustained duration of bronchodilator effect over 24 h following once-daily administration, with a PK profile that is commensurate with low systemic exposure.

A 28-day, randomized, double-blind, placebo-controlled, parallel group study of nebulized revefenacin in patients with chronic obstructive pulmonary disease.

BACKGROUND: Revefenacin is a once-daily long-acting muscarinic antagonist (LAMA) in clinical development for the treatment of patients with chronic obstructive pulmonary disease (COPD). In a dose-ranging study, nebulized once-daily revefenacin had a long duration of action in patients after 7 days' administration of doses up to 700 µg. In this multiple-dose study, the bronchodilation efficacy and adverse events profile were characterized in patients administered nebulized revefenacin once daily for 28 days. METHODS: A total of 355 COPD patients (mean age 62 years, mean forced expiratory volume in 1 s [FEV1] 44% of predicted) were randomized in a double-blind, placebo-controlled parallel group study. Inhaled corticosteroids as well as short-acting bronchodilators were permitted. Once-daily treatments (44, 88, 175 or 350 µg revefenacin or matching placebo) were administered by a standard jet nebulizer, for 28 days. The primary endpoint was change from baseline in D28 trough FEV1, and secondary endpoints included weighted mean FEV1 over 0 to 24 h and rescue medication (albuterol) use. Safety evaluations included adverse events, laboratory assessments, electrocardiograms and 24-h Holter profiles. RESULTS: Revefenacin (88, 175 and 350 µg) significantly improved D28 trough FEV1 over placebo (187.4, 166.6 and 170.6 mL, respectively, all p < 0.001); 44 µg produced a sub-therapeutic response. At doses ≥88 µg, more than 80% of patients achieved at least a 100-mL increase from baseline FEV1 in the first 4 h post dose compared with 33% of placebo patients. For doses ≥88 µg, D28 24 h weighted mean differences from placebo for FEV1 were numerically similar to respective trough FEV1 values, indicating bronchodilation was sustained for 24 h post dose. Doses ≥88 µg reduced the average number of albuterol puffs/day by more than one puff/day. The 350 µg dose did not demonstrate additional efficacy over that observed with 175 µg revefenacin. Revefenacin was generally well tolerated, with minimal reports of systemic anti-cholinergic effects. CONCLUSIONS: These data suggest that 88 and 175 µg revefenacin are appropriate doses for use in longer-term safety and efficacy trials. Revefenacin offers the potential for the first once-daily LAMA for nebulization in patients with COPD who require or prefer a nebulized drug delivery option. TRIAL REGISTRATION: ClinicalTrials.gov NCT02040792 . Registered January 16, 2014.

Multivalent design of long-acting ß(2)-adrenoceptor agonists incorporating biarylamines.

A series of potent ß2-adrenoceptor agonists incorporating a biarylamine secondary binding group was identified. The previously reported milveterol (5), identified by a multivalent approach and containing a typical ß2-agonist primary binding group linked via a phenethylamine linker to a hydrophilic secondary binding group, served as an initiation point. A more hydrophobic set of secondary binding groups was explored, prepared rapidly from a common intermediate by Buchwald-Hartwig amination. TD-5471 (25), a potent and selective full agonist of the human ß2-adrenoceptor, was identified as the most promising agent. It is potent, with slow onset in an in vitro guinea pig trachea model and shows a dose-dependent and long duration of action in an in vivo guinea pig model of bronchoprotection. TD-5471 is structurally differentiated from milveterol and its long duration of action is consistent with a correlation with hydrophobicity observed in other long-acting ß2-agonist discovery programs.

Discovery of TD-4306, a long-acting ß2-agonist for the treatment of asthma and COPD.

A multivalent approach focused on amine-based secondary binding groups was applied to the discovery of long-acting inhaled ß2-agonists. Addition of amine moieties to the neutral secondary binding group of an existing ß2-agonist series was found to provide improved in vivo efficacy, but also led to the formation of biologically active aldehyde metabolites which were viewed as a risk for the development of these compounds. Structural simplification of the scaffold and blocking the site of metabolism to prevent aldehyde formation afforded a potent series of dibasic ß2-agonists with improved duration of action relative to their monobasic analogs. Additional optimization led to the discovery of 29 (TD-4306), a potent and selective ß2-agonist with potential for once-daily dosing.

A multivalent approach to the discovery of long-acting ß(2)-adrenoceptor agonists for the treatment of asthma and COPD.

A multivalent approach was applied to the design of long-acting inhaled ß(2)-adrenoceptor agonists. A series of dimeric arylethanolamines based on the short acting ß(2)-adrenoceptor agonist albuterol were prepared, varying the nature and length of the linker between the basic nitrogens. None of the C(2)-symmetric dimers demonstrated increased potency, however dimer 5j, derived from 4-phenethylamine, was found to have increased binding potency in vitro relative to the parent monomer. Optimization of this structure led to the identification of 22 (milveterol) which demonstrates high potency in vitro and long duration of action in a guinea pig model of bronchoprotection.

A multivalent approach to drug discovery for novel antibiotics.

The design, synthesis and antibacterial activity of novel glycopeptide/beta-lactam heterodimers is reported. Employing a multivalent approach to drug discovery, vancomycin and cephalosporin synthons, A and B respectively, were chemically linked to yield heterodimer antibiotics. These novel compounds were designed to inhibit Gram-positive bacterial cell wall biosynthesis by simultaneously targeting the principal cellular targets of both glycopeptides and beta-lactams. The antibiotics 8a-f displayed remarkable potency against a wide range of Gram-positive organisms including methicillin-resistant Staphylococcus aureus (MRSA). Compound 8e demonstrated excellent bactericidal activity against MRSA (ATCC 33591) and initial evidence supports a multivalent mechanism of action for this important new class of antibiotic.

Exploring the positional attachment of glycopeptide/beta-lactam heterodimers.

Further investigations towards novel glycopeptide/beta-lactam heterodimers are reported. Employing a multivalent approach to drug discovery, vancomycin and cephalosporin synthons, 4, 2, 5 and 10, 18, 25 respectively, were chemically linked to yield heterodimer antibiotics. These novel compounds were designed to inhibit Gram-positive bacterial cell wall biosynthesis by simultaneously targeting the principal cellular targets of both glycopeptides and beta-lactams. The positional attachment of both the vancomycin and the cephalosporin central cores has been explored and the SAR is reported. This novel class of bifunctional antibiotics 28-36 all displayed remarkable potency against a wide range of Gram-positive organisms, including methicillin-resistant Staphylococcus aureus (MRSA). A subset of compounds, 29, 31 and 35 demonstrated excellent bactericidal activity against MRSA (ATCC 33591) and 31 and 35 also exhibited superb in vivo efficacy in a mouse model of MRSA infection. As a result of this work compound 35 was selected as a clinical candidate, TD-1792.