The discovery and development of gefapixant.

Gefapixant is the approved generic name for a compound also known as MK-7264, and prior to that AF-219 and RO-4926219. It is the first-in-class clinically developed antagonist for the P2X3 subtype of trimeric ionotropic purinergic receptors, a family of ATP-gated excitatory ion channels, showing nanomolar potency for the human P2X3 homotrimeric channel and essentially no activity at related channels devoid of P2X3 subunits. As the first P2X3 antagonist to have progressed into clinical studies it has now progressed to the point of successful completion of Phase 3 investigations for the treatment of cough, and the NDA application is under review with US FDA for treatment of refractory chronic cough or unexplained chronic cough. The molecule was discovered in the laboratories of Roche Pharmaceuticals in Palo Alto, California, but clinical development then continued with the formation of Afferent Pharmaceuticals for the purpose of identifying the optimal therapeutic indication for this novel mechanism and establishing a clinical plan for development in the optimal patient populations selected. Geoff Burnstock was a close collaborator and advisor to the P2X3 program for close to two decades of discovery and development. Progression of gefapixant through later stage clinical studies has been conducted by the research laboratories of Merck & Co., Inc., Kenilworth, NJ, USA (MRL; following acquisition of Afferent in 2016), who may commercialize the product once authorization has been granted by regulatory authorities.

Telavancin versus vancomycin for the treatment of complicated skin and skin-structure infections associated with surgical procedures.

BACKGROUND: We compared telavancin with vancomycin for the treatment of complicated skin and skin-structure infections (cSSSI) caused by Gram-positive bacteria. METHODS: This was a retrospective analysis of clinical and microbiologic efficacy assessed at test-of-cure (7 to 14 days after completing therapy) in 194 patients from 2 randomized, double-blind clinical trials comparing telavancin (10 mg/kg intravenous [IV] every 24 hours; n = 101) with vancomycin (1 g IV every 12 hours; n = 93) for the treatment of cSSSI. RESULTS: Baseline characteristics were similar for both treatment groups. Clinical cure and microbiologic eradication rates demonstrated consistent trends favoring telavancin over vancomycin; however, the differences were not statistically significant. The incidence of adverse events was mostly similar between groups. CONCLUSIONS: The efficacy of telavancin was at least equivalent to that of vancomycin for the treatment of cSSSI. These data suggest that telavancin may be a useful alternative for treatment of cSSSI caused by S. aureus, particularly MRSA.

Intrapulmonary distribution of intravenous telavancin in healthy subjects and effect of pulmonary surfactant on in vitro activities of telavancin and other antibiotics.

Steady-state concentrations of telavancin, a novel, bactericidal lipoglycopeptide, were determined in the plasma, pulmonary epithelial lining fluid (ELF), and alveolar macrophages (AMs) of 20 healthy subjects. Telavancin at 10 mg of drug/kg of body weight/day was administered as a 1-h intravenous infusion on three successive days, with bronchoalveolar lavage performed on five subjects, each at 4, 8, 12, and 24 h after the last dose. Plasma samples were collected before the first and third infusions and at 1, 2, 3, 4, 8, 12, and 24 h after the third infusion. The plasma telavancin concentration-time profile was as reported previously. Telavancin (mean +/- standard deviation) penetrated well into ELF (3.73 +/- 1.28 microg/ml at 8 h and 0.89 +/- 1.03 microg/ml at 24 h) and extensively into AMs (19.0 +/- 16.8 microg/ml at 8 h, 45.0 +/- 22.4 microg/ml at 12 h, and 42.0 +/- 31.4 microg/ml at 24 h). Mean concentrations in AMs and plasma at 12 h were 45.0 microg/ml and 22.9 microg/ml (mean AM/plasma ratio, 1.93), respectively, and at 24 h were 42.0 microg/ml and 7.28 microg/ml (mean AM/plasma ratio, 6.67), respectively. Over the entire dosing interval, telavancin was present in ELF and AMs at concentrations up to 8-fold and 85-fold, respectively, above its MIC 90 for methicillin-resistant Staphylococcus aureus (0.5 microg/ml). Pulmonary surfactant did not affect telavancin's in vitro antibacterial activity. Telavancin was well tolerated. These results support the proposal for further clinical evaluation of telavancin for treating gram-positive respiratory infections.

Bailout use of platelet glycoprotein IIb-IIIa inhibition during coronary stent implantation: observations from the ESPRIT trial.

Glycoprotein (GP) IIb/IIIa inhibitors are often used as a rescue or bailout therapy to manage complications arising during percutaneous coronary intervention, rather than as prophylactic treatment. We sought to identify the characteristics and outcomes of patients requiring bailout treatment. The ESPRIT trial randomized 2,064 patients to receive eptifibatide or placebo starting immediately before percutaneous coronary intervention (PCI). Bailout therapy was used in 77 patients: 43 (4.2%) randomized to placebo and 34 (3.3%) to eptifibatide (p = 0.3). Bailout therapy for thrombosis was used more often in the placebo group (2.1% versus 1.0%; p = 0.03). Multivariable predictors of bailout included a greater than or equal to 90% stenosis, or visible thrombus on the baseline angiogram, and no aspirin pre-treatment before PCI. However, overall the model predicted bailout poorly (c-index = 0.64). The need for bailout cannot be reliably predicted using baseline characteristics. Patients experiencing complications have poor clinical outcomes despite bailout use of GP IIb/IIIa inhibitors.

Optimal duration of eptifibatide infusion in percutaneous coronary intervention (an ESPRIT substudy).

Although randomized trials have clearly demonstrated the clinical efficacy with regimens of platelet glycoprotein IIb/IIIa antagonists that result in >80% inhibition of baseline platelet aggregation in percutaneous coronary intervention (PCI), there are no data available concerning the optimal duration of infusion of these agents. In an era when the length of hospitalization has a major impact on health care costs, the determination of the optimal duration of the infusion of these drugs after PCI is of great relevance. The investigators therefore sought to determine the optimal length of the infusion of eptifibatide after PCI by analyzing the outcomes of patients enrolled in the Enhanced Suppression of the Platelet IIb/IIIa Receptor With Integrilin Therapy trial who were randomized to treatment with eptifibatide.

Temporal spectrum of ischemic complications with percutaneous coronary intervention: the ESPRIT experience.

We determined the timing of ischemic complications within 30 days after percutaneous coronary intervention (PCI) in patients enrolled in the Enhanced Suppression of the Platelet IIb/IIIa Receptor with Integrilin Therapy (ESPRIT) trial. Complications (death, myocardial infarction [MI], target vessel revascularization) occurred in 178 of 2064 patients (8.6%) within 30 days. More than 85% of complications occurred within the 24 hours following randomization, with the greatest risk hazard at 12-18 hours. Unexpectedly, 31% of patients who ultimately met criteria for an endpoint MI within 24 hours of PCI had completely normal CK-MB concentrations at the first 6-hour measurement. There was no rebound increase in events after cessation of eptifibatide. Treatment benefit persisted to 30 days. Post-procedural MI is often not detected until greater than or equal to 12 hours after PCI. Treatment with a glycoprotein IIb/IIIa inhibitor is the only modifiable parameter that reduces the risk for early ischemic complications.

Ethics and equipoise: rationale for a placebo-controlled study design of platelet glycoprotein IIb/IIIa inhibition in coronary intervention.

Rarely is it straightforward to specify the design and parameters of a clinical trial investigating an alternative therapy where effective therapies already exist. If existing therapeutic interventions are highly efficacious, safe, inexpensive, and firmly entrenched, an active-control design becomes the logical first choice. Short of this absolute condition, however, the merits and realities of the scientific, clinical, corporate, and regulatory environments need to be weighed before determining the appropriate approach. A state of clinical equipoise with regard to the use of glycoprotein (GP) IIb/IIIa therapy in percutaneous coronary intervention (PCI) provided the unique opportunity to address the complexities in selecting a placebo-controlled design for the Enhanced Suppression of the Platelet IIb/IIIa Receptor with Integrilin Trial (ESPRIT). ESPRIT investigators assessed whether a high dose of eptifibatide would improve the outcomes of patients undergoing coronary stenting. By using the example of the ESPRIT trial, we examine factors warranting the need for this trial and evaluate the process whereby the United States Food and Drug Administration (FDA) gave approval for a placebo-controlled design. Although the focus of this trial is GP IIb/IIIa inhibition therapy, the issues pertaining to the trial and how they were resolved are general enough to be applied to the design and conduct of clinical trials across a broad spectrum of illnesses and therapeutic modalities.

Combination reperfusion therapy with eptifibatide and reduced-dose tenecteplase for ST-elevation myocardial infarction: results of the integrilin and tenecteplase in acute myocardial infarction (INTEGRITI) Phase II Angiographic Trial.

OBJECTIVES: The goal of this study was to evaluate combinations of eptifibatide with reduced-dose tenecteplase (TNK) in ST-elevation myocardial infarction (STEMI). BACKGROUND: Glycoprotein IIb/IIIa inhibitors enhance thrombolysis. The role of combination therapy in clinical practice remains to be established. METHODS: Patients (n = 438) with STEMI <6 h were enrolled. In dose-finding, 189 patients were randomized to different combinations of double-bolus eptifibatide and reduced-dose TNK. In dose-confirmation, 249 patients were randomized 1:1 to eptifibatide 180 microg/kg bolus, 2 microg/kg/min infusion, and 180 microg/kg bolus 10 min later (180/2/180) plus half-dose TNK (0.27 mg/kg) or standard-dose (0.53 mg/kg) TNK monotherapy. All patients received aspirin and unfractionated heparin (60 U/kg bolus; infusion 7 U/kg/h [combination], 12 U/kg/h [monotherapy]). The primary end point was Thrombolysis In Myocardial Infarction (TIMI) grade 3 epicardial flow at 60 min. RESULTS: In dose-finding, TIMI grade 3 flow rates were similar across groups (64% to 68%). Arterial patency was highest for eptifibatide 180/2/180 plus half-dose TNK (96%, p = 0.02 vs. eptifibatide 180/2/90 plus half-dose TNK). In dose-confirmation, this combination, compared with TNK monotherapy, tended to achieve more TIMI 3 flow (59% vs. 49%, p = 0.15), arterial patency (85% vs. 77%, p = 0.17), and ST-segment resolution (median 71% vs. 61%, p = 0.08) but was associated with more major hemorrhage (7.6% vs. 2.5%, p = 0.14) and transfusions (13.4% vs. 4.2%, p = 0.02). Intracranial hemorrhage occurred in 1.0%, 0.6%, and 1.7% of patients treated with any combination, eptifibatide 180/2/180 and half-dose TNK, and TNK monotherapy, respectively. CONCLUSIONS: Double-bolus eptifibatide (180/2/180) plus half-dose TNK tended to improve angiographic flow and ST-segment resolution compared with TNK monotherapy but was associated with more transfusions and non-cerebral bleeding. Further study is needed before this combination can be recommended for general use.

Treatment effects of eptifibatide in planned coronary stent implantation in patients with chronic kidney disease (ESPRIT Trial).

The role of platelet glycoprotein IIb/IIIa inhibitor therapy in patients with mild renal impairment is not well characterized. Our objective was to explore the associations of creatinine clearance (CrCl) with outcomes in a trial of eptifibatide therapy in patients who underwent percutaneous coronary intervention (PCI). We analyzed 48-hour and 30-day outcomes of patients enrolled in the Enhanced Suppression of the Platelet IIb/IIIa Receptor with Integrilin Therapy (ESPRIT) trial. Patients were randomly assigned to placebo or eptifibatide as an adjunct to stent implantation (1,755 with CrCl > or =60 ml/min and 289 with CrCl <60 ml/min). CrCl was calculated using the Cockcroft and Gault formula, and the associations of CrCl with outcomes were evaluated using logistic regression models. Patients with CrCl <60 ml/min were more likely to be older, women, hypertensive, and have a history of coronary artery bypass surgery, stroke, or peripheral vascular disease. The interaction of eptifibatide with CrCl had borderline significance for the 30-day outcome (p = 0.109). Treatment effect trended toward a greater magnitude in patients with lower CrCl (60 ml/min) (odds ratio 0.53, confidence interval 0.34 to 0.83) compared with those with higher CrCl (90 ml/min) (odds ratio 0.68, confidence interval 0.49 to 0.94). An accompanying increase in bleeding risk also was not apparent with lower CrCl. The treatment effect of eptifibatide is realized regardless of renal function and trends toward being greater in patients with mild renal impairment.

Comparison of one-year outcomes following coronary artery stenting in diabetic versus nondiabetic patients (from the Enhanced Suppression of the Platelet IIb/IIIa Receptor With Integrilin Therapy [ESPRIT] Trial).

For patients undergoing nonurgent coronary stent implantation, blockade of the glycoprotein IIb/IIIa receptor with eptifibatide reduces the incidence of ischemic complications. We evaluated the interaction of eptifibatide with diabetes in patients who underwent this procedure by analyzing the 1-year outcomes of those enrolled in the Enhanced Suppression of the Platelet IIb/IIIa Receptor with Integrilin Therapy (ESPRIT) trial (466 diabetic and 1,595 nondiabetic patients). At 1 year, the composite end point of death, myocardial infarction (MI), or target vessel revascuarlization (TVR) was higher in diabetic patients (24.5% vs 18.4%; p = 0.008). At 1 year, eptifibatide had a similar effect on the composite end point of death, MI, or TVR in diabetic (hazards ratio [HR] 0.71, 95% confidence interval [CI] 0.49 to 1.04) and nondiabetic patients (HR 0.80, 95% CI 0.63 to 0.99). A similar treatment effect was also seen on death or MI in both groups. The 1-year mortality rate for diabetic patients assigned to placebo was 3.5% versus 1.3% for patients receiving eptifibatide (HR 0.37, 95% CI 0.10 to 1.41); the latter rate was similar to the mortality rate of 1.4% for nondiabetic patients in the eptifibatide group. However, eptifibatide did not have a significant effect on TVR in diabetic patients (HR 0.90, 95% CI 0.57 to 1.41). Our data suggest that treatment with eptifibatide is associated with a similar relative reduction in adverse ischemic complications in diabetic and nondiabetic patients undergoing coronary stent implantation. There is no evidence of a statistical interaction in the treatment effect of eptifibatide between patients with and without diabetes.

Long-term efficacy of platelet glycoprotein IIb/IIIa integrin blockade with eptifibatide in coronary stent intervention.

CONTEXT: In the Enhanced Suppression of the Platelet IIb/IIIa Receptor with Integrilin Therapy (ESPRIT) trial, treatment with eptifibatide, a platelet glycoprotein IIb/IIIa integrin blocker, was found to reduce the ischemic complications of nonurgent coronary stent implantation at 48 hours and 30 days. OBJECTIVE: To determine whether eptifibatide treatment continues to provide durable, long-term benefit after coronary stent intervention. DESIGN AND SETTING: The ESPRIT trial was a randomized, double-blind, placebo-controlled, parallel-group, crossover-permitted trial conducted from June 1999 through February 2000 at 92 tertiary care centers in the United States and Canada. PARTICIPANTS: A total of 2064 patients scheduled to undergo nonurgent percutaneous coronary intervention with stent implantation. INTERVENTION: Patients were randomly assigned to receive placebo (n = 1024) or eptifibatide (two 180-microg/kg boluses, 10 minutes apart, with a continuous infusion of 2.0 microg/kg per minute; n = 1040), started immediately before stent implantation and continued for 18 to 24 hours. Patients also received aspirin, heparin, and a thienopyridine. MAIN OUTCOME MEASURES: Composite rates of death or myocardial infarction (MI) and death, infarction, or target vessel revascularization during the 12 months after enrollment. RESULTS: Complete follow-up data were available for 988 patients given eptifibatide (95.0%) and 976 patients given placebo (95.3%). By 12 months, the composite of death or MI had occurred in 8.0% of eptifibatide-treated patients and in 12.4% of placebo-treated patients (hazard ratio [HR], 0.63; 95% confidence interval [CI], 0.48-0.83; P =.001). The composite rate of death, MI, or target vessel revascularization was 17.5% in eptifibatide-treated patients vs 22.1% in placebo-treated patients (HR, 0.76; 95% CI, 0.63-0.93; P =.007). CONCLUSIONS: Long-term outcomes of nonurgent coronary stent implantation appear to be improved through blockade of the platelet glycoprotein IIb/IIIa integrin with eptifibatide.

Relationship of creatine kinase-myocardial band release to Thrombolysis in Myocardial Infarction perfusion grade after intracoronary stent placement: an ESPRIT substudy.

BACKGROUND: The etiology of creatine kinase-myocardial band (CK-MB) release after percutaneous coronary intervention (PCI) remains unclear. The goal of this study was to evaluate the relationship of both epicardial and tissue level perfusion at the completion of stent placement to CK-MB release after the procedure. Given the high rates of Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow after PCI, we hypothesized that abnormalities in tissue level perfusion would instead explain CK-MB release. METHODS: Data were drawn from the angiographic substudy of the Enhanced Suppression of the Platelet IIb/IIIa Receptor With Integrilin Therapy (ESPRIT) trial of eptifibatide versus placebo in patients undergoing planned coronary stent implantation. In the substudy, cinefilms of 65 patients were analyzed by an angiographic core laboratory blinded to enzymatic and clinical outcomes. RESULTS: The release of CK-MB was not associated with TIMI grade 3 flow or the corrected TIMI frame count; 100% of patients had TIMI grade 3 flow at the completion of PCI. In contrast, tissue level perfusion using the TIMI myocardial perfusion grade (TMPG) was related to postintervention CK-MB release: patients with a closed myocardium (TMPG 0/1) or delayed myocardial perfusion (TMPG 2) had an average CK-MB release 2.2 +/- 2.7 times the upper limit of normal (n = 34), whereas those patients with normal myocardial perfusion (TMPG 3, n = 24) had CK-MB 0.8 +/- 0.6 times the upper limit of normal (P =.01). Although no patients with TMPG 3 sustained death/myocardial infarction/urgent target vessel revascularization or thrombotic bailout, 17.7% of patients with TMPG 0/1/2 did by 48 hours (P =.037). CONCLUSIONS: Impaired tissue level perfusion as assessed by the TMPG and not epicardial coronary blood flow is associated with CK-MB elevation after PCI. These data provide a pathophysiologic link between impaired tissue level perfusion, post-PCI infarction, and adverse clinical outcomes.

Outcomes of patients with acute coronary syndromes and prior coronary artery bypass grafting: results from the platelet glycoprotein IIb/IIIa in unstable angina: receptor suppression using integrilin therapy (PURSUIT) trial.

BACKGROUND: Patients with prior CABG with a subsequent non-ST-segment elevation acute coronary syndrome (ACS) pose an increasingly important clinical problem. Although GP IIb/IIIa inhibitors have improved the outcome of patients with ACS, their efficacy in patients with prior CABG has not been previously evaluated. Methods and Results- We analyzed the 30- and 180-day outcomes of patients with prior CABG enrolled in the Platelet Glycoprotein IIb/IIIa in Unstable Angina: Receptor Suppression Using Integrilin Therapy (PURSUIT) trial. In this trial, which evaluated the efficacy of eptifibatide in patients with ACS, 1134 patients (12%) with prior CABG and 8321 without prior CABG were enrolled. After adjusting for differences in baseline characteristics and treatment, patients with prior CABG had a significantly higher mortality rates at 30 days (hazard ratio [HR], 1.45 [95% CI, 1.06 to 1.98]; P=0.019) and at 180 days (HR, 1.32 [95% CI, 1.04 to 1.67]; P=0.021). At 30 days, there was a similar effect on the primary end point of death or myocardial infarction in the eptifibatide group versus the placebo group in prior CABG patients (unadjusted HR, 0.90 [95% CI, 0.67 to 1.20]) and in patients without a history of CABG (unadjusted HR, 0.89 [95% CI, 0.80 to 0.99]). CONCLUSIONS: Patients with prior CABG with non-ST-segment elevation ACS have a significantly worse prognosis than do patients without a history of CABG. The treatment effect of eptifibatide in the prior CABG group was similar to the effect seen in patients without prior CABG.