Femoral Vascular Closure Devices and Bleeding, Hemostasis, and Ambulation Following Percutaneous Coronary Intervention

Background The effectiveness of vascular closure devices (VCDs) to reduce bleeding after transfemoral percutaneous coronary intervention remains unsettled. Methods and Results Participants in the REGULATE-PCI (Effect of the REG1 anticoagulation system versus bivalirudin on outcomes after percutaneous coronary intervention) trial who underwent transfemoral percutaneous coronary intervention with VCD implantation were compared with those who underwent manual compression. The primary effectiveness end point was type 2, 3, or 5 Bleeding Academic Research Consortium access site bleeding at day 3. Univariate and multivariate analyses were adjusted by the inverse probability weighting method using propensity score. Time to hemostasis and time to ambulation were compared between groups. Of the 1580 patients who underwent transfemoral percutaneous coronary intervention, 1004 (63.5%) underwent VCD implantation and 576 (36.5%) had manual compression. The primary effectiveness end point occurred in 64 (6.4%) participants in the VCD group and in 38 (6.6%) participants in the manual compression group (inverse probability weighting-adjusted odds ratio, 1.02 [95% CI, 0.77-1.36]; P=0.89). There were statistically significant 2-way interactions between VCD use and female sex, chronic kidney disease, and use of high-potency P2Y12 inhibition (ticagrelor or prasugrel) (P<0.05 for all) with less bleeding with VCD use in these high-risk subgroups. Median time to hemostasis and time to ambulation were shorter in the VCD versus the manual compression group (P<0.01 for both). Conclusions Following transfemoral percutaneous coronary intervention, VCD use is associated with a shorter time to hemostasis and time to ambulation but not less bleeding. Further study of patients with high-bleeding risk is required, including women, patients with chronic kidney disease, and those using high-potency P2Y12 inhibitors. Registration URL: https://clinicaltrials.gov/ct2/show/NCT01848106; Unique identifier: NCT01848106.

Navigating the Future of Cardiovascular Drug Development-Leveraging Novel Approaches to Drive Innovation and Drug Discovery: Summary of Findings from the Novel Cardiovascular Therapeutics Conference

PURPOSE

The need for novel approaches to cardiovascular drug development served as the impetus to convene an open meeting of experts from the pharmaceutical industry and academia to assess the challenges and develop solutions for drug discovery in cardiovascular disease.

METHODS

The Novel Cardiovascular Therapeutics Summit first reviewed recent examples of ongoing or recently completed programs translating basic science observations to targeted drug development, highlighting successes (protein convertase sutilisin/kexin type 9 [PCSK9] and neprilysin inhibition) and targets still under evaluation (cholesteryl ester transfer protein [CETP] inhibition), with the hope of gleaning key lessons to successful drug development in the current era. Participants then reviewed the use of innovative approaches being explored to facilitate rapid and more cost-efficient evaluations of drug candidates in a short timeframe.

RESULTS

We summarize observations gleaned from this summit and offer insight into future cardiovascular drug development.

CONCLUSIONS

The rapid development in genetic and high-throughput drug evaluation technologies, coupled with new approaches to rapidly evaluate potential cardiovascular therapies with in vitro techniques, offer opportunities to identify new drug targets for cardiovascular disease, study new therapies with better efficiency and higher throughput in the preclinical setting, and more rapidly bring the most promising therapies to human testing. However, there must be a critical interface between industry and academia to guide the future of cardiovascular drug development. The shared interest among academic institutions and pharmaceutical companies in developing promising therapies to address unmet clinical needs for patients with cardiovascular disease underlies and guides innovation and discovery platforms that are significantly altering the landscape of cardiovascular drug development.

Direct factor IXa inhibition with the RNA-aptamer pegnivacogin reduces platelet reactivity in vitro and residual platelet aggregation in patients with acute coronary syndromes

BACKGROUND

Residual platelet reactivity is a predictor of poor prognosis in patients with acute coronary syndromes (ACSs) undergoing percutaneous coronary intervention. Thrombin is a major platelet activator and upon initiation of the coagulation cascade, it is subsequently produced downstream of factor IXa, which itself is known to be increased in ACS. Pegnivacogin is a novel RNA-aptamer based factor IXa inhibitor featuring a reversal agent, anivamersen. We hypothesized that pegnivacogin could reduce platelet reactivity.

METHODS

Whole blood samples from healthy volunteers were incubated in vitro in the presence and absence of pegnivacogin and platelet reactivity was analysed. In addition, platelet aggregometry was performed in blood samples from ACS patients in the RADAR trial featuring the intravenous administration of pegnivacogin as well as reversal by anivamersen.

RESULTS

In vitro, pegnivacogin significantly reduced adenosine diphosphate-induced CD62P-expression (100% vs. 89.79±4.04%, p=0.027, n=9) and PAC-1 binding (100% vs. 83.02±4.08%, p=0.010, n=11). Platelet aggregation was reduced (97.71±5.30% vs. 66.53±9.92%, p=0.013, n=10) as evaluated by light transmission aggregometry. In the presence of the RNA-aptamer reversal agent anivamersen, neither CD62P-expression nor platelet aggregation was attenuated. In patients with ACS treated with aspirin and clopidogrel, residual platelet aggregation was significantly reduced 20 min after intravenous bolus of 1 mg/kg pegnivacogin (100% versus 43.21±8.23%, p=0.020).

CONCLUSION

Inhibition of factor IXa by pegnivacogin decreases platelet activation and aggregation in vitro. This effect was negated by anivamersen. In ACS patients, platelet aggregation was significantly reduced after intravenous pegnivacogin. An aptamer-based anticoagulant inhibiting factor IXa therefore might be a promising antithrombotic strategy in ACS patients.

Effect of the REG1 anticoagulation system versus bivalirudin on outcomes after percutaneous coronary intervention (REGULATE-PCI): a randomised clinical trial

BACKGROUND

REG1 is a novel anticoagulation system consisting of pegnivacogin, an RNA aptamer inhibitor of coagulation factor IXa, and anivamersen, a complementary sequence reversal oligonucleotide. We tested the hypothesis that near complete inhibition of factor IXa with pegnivacogin during percutaneous coronary intervention, followed by partial reversal with anivamersen, would reduce ischaemic events compared with bivalirudin, without increasing bleeding.

METHODS

We did a randomised, open-label, active-controlled, multicentre, superiority trial to compare REG1 with bivalirudin at 225 hospitals in North America and Europe. We planned to randomly allocate 13,200 patients undergoing percutaneous coronary intervention in a 1:1 ratio to either REG1 (pegnivacogin 1 mg/kg bolus [>99% factor IXa inhibition] followed by 80% reversal with anivamersen after percutaneous coronary intervention) or bivalirudin. Exclusion criteria included ST segment elevation myocardial infarction within 48 h. The primary efficacy endpoint was the composite of all-cause death, myocardial infarction, stroke, and unplanned target lesion revascularisation by day 3 after randomisation. The principal safety endpoint was major bleeding. Analysis was by intention to treat. This trial is registered at ClinicalTrials.gov, identifier NCT01848106. The trial was terminated early after enrolment of 3232 patients due to severe allergic reactions.

FINDINGS

1616 patients were allocated REG1 and 1616 were assigned bivalirudin, of whom 1605 and 1601 patients, respectively, received the assigned treatment. Severe allergic reactions were reported in ten (1%) of 1605 patients receiving REG1 versus one (<1%) of 1601 patients treated with bivalirudin. The composite primary endpoint did not differ between groups, with 108 (7%) of 1616 patients assigned REG1 and 103 (6%) of 1616 allocated bivalirudin reporting a primary endpoint event (odds ratio [OR] 1·05, 95% CI 0·80-1·39; p=0·72). Major bleeding was similar between treatment groups (seven [<1%] of 1605 receiving REG1 vs two [<1%] of 1601 treated with bivalirudin; OR 3·49, 95% CI 0·73-16·82; p=0·10), but major or minor bleeding was increased with REG1 (104 [6%] vs 65 [4%]; 1·64, 1·19-2·25; p=0·002).

INTERPRETATION

The reversible factor IXa inhibitor REG1, as currently formulated, is associated with severe allergic reactions. Although statistical power was limited because of early termination, there was no evidence that REG1 reduced ischaemic events or bleeding compared with bivalirudin.

FUNDING

Regado Biosciences Inc.

Use of the REG1 anticoagulation system in patients with acute coronary syndromes undergoing percutaneous coronary intervention: results from the phase II RADAR-PCI study

AIMS

We sought to determine the feasibility of conducting percutaneous coronary intervention (PCI) in high-risk acute coronary syndrome (ACS) patients utilising the REG1 system consisting of pegnivacogin, an aptameric factor IXa inhibitor, and its controlling agent anivamersen.

METHODS AND RESULTS

In RADAR, ACS patients were randomised to pegnivacogin 1 mg/kg with 25%, 50%, 75%, or 100% anivamersen reversal or unfractionated heparin. Of the 640 patients randomised, 388 (61%) underwent PCI. Major modified ACUITY 30-day bleeding rates were 18% (25% reversal), 12% (50% reversal), 9% (75% reversal), and 7% (100% reversal), compared with 11% with heparin. The corresponding total bleeding rates were 68%, 39%, 35%, 34%, and 38% (heparin). Ischaemic events were less frequent in those receiving pegnivacogin versus heparin (4.4% vs. 7.3%, p=0.3). Thirty-day urgent TVR (1.1% vs. 0.9%, p=1.0), myocardial infarction (4.0% vs. 6.4%, p=0.3), and angiographic complication (11.2% and 10.8%, p=0.9) rates were similar with pegnivacogin and heparin. There were no incidences of clot formation on guidewires or catheters.

CONCLUSIONS

High-level factor IXa inhibition in ACS patients undergoing PCI, with at least 50% reversal, has a favourable bleeding profile and appears effective at suppressing ischaemic events and thrombotic complications. Larger phase trials in PCI are warranted.

CLINICAL TRIALS REGISTRATION

ClinicalTrials.gov NCT00932100.

Safety of very early sheath removal in patients treated with REG1 for acute coronary syndromes: insights from the RADAR trial

BACKGROUND

RADAR compared REG1 (25%, 50%, 75%, 100% reversal) with unfractionated heparin (UFH) in 640 acute coronary syndrome (ACS) patients (479 REG1 patients, 161 UFH patients) undergoing an invasive management strategy. We sought to determine whether the REG1 anticoagulation system allows for safer early arterial sheath removal following cardiac catheterization.

METHODS

REG1 patients had arterial sheath removal immediately post catheterization. We measured arterial sheath management outcomes and vascular access complications in patients who had sheath removal without vascular closure device implantation; 461 patients were included (349 REG1 patients, 112 UFH patients).

RESULTS

The median (25th, 75th) time from end of catheterization to arterial sheath removal was shorter in REG1 arms regardless of reversal strategy (26 minutes [18, 46]) compared with UFH (210 minutes [102, 342]). There was no increase in median time from sheath removal to hemostasis (10 minutes [10, 20] and 10 minutes [10, 20]; P=.60); vascular access-site bleeding complications were numerically fewer with REG1 than UFH (6% vs 11%; odds ratio [OR], 0.57; 95% CI, 0.27-1.18; P=.14). There were no differences in time to ambulation or hospital length of stay between the groups.

CONCLUSIONS

REG1 allows for very early arterial sheath removal following cardiac catheterization without increasing the time to hemostasis or vascular access-site bleeding complications. Further studies are needed to determine whether anticoagulation with REG1 will translate into shorter hospital lengths of stay and reduced costs in ACS patients.

A Phase 2, randomized, partially blinded, active-controlled study assessing the efficacy and safety of variable anticoagulation reversal using the REG1 system in patients with acute coronary syndromes: results of the RADAR trial

AIMS

We sought to determine the degree of anticoagulation reversal required to mitigate bleeding, and assess the feasibility of using pegnivacogin to prevent ischaemic events in acute coronary syndrome (ACS) patients managed with an early invasive approach. REG1 consists of pegnivacogin, an RNA aptamer selective factor IXa inhibitor, and its complementary controlling agent, anivamersen. REG1 has not been studied in invasively managed patients with ACS nor has an optimal level of reversal allowing safe sheath removal been defined.

METHODS AND RESULTS

Non-ST-elevation ACS patients (n = 640) with planned early cardiac catheterization via femoral access were randomized 2:1:1:2:2 to pegnivacogin with 25, 50, 75, or 100% anivamersen reversal or heparin. The primary endpoint was total ACUITY bleeding through 30 days. Secondary endpoints included major bleeding and the composite of death, myocardial infarction, urgent target vessel revascularization, or recurrent ischaemia. Enrolment in the 25% reversal arm was suspended after 41 patients. Enrolment was stopped after three patients experienced allergic-like reactions. Bleeding occurred in 65, 34, 35, 30, and 31% of REG1 patients with 25, 50, 75, and 100% reversal and heparin. Major bleeding occurred in 20, 11, 8, 7, and 10% of patients. Ischaemic events occurred in 3.0 and 5.7% of REG1 and heparin patients, respectively.

CONCLUSION

At least 50% reversal is required to allow safe sheath removal after cardiac catheterization. REG1 appears a safe strategy to anticoagulate ACS patients managed invasively and warrants further investigation in adequately powered clinical trials of patients who require short-term high-intensity anticoagulation.

Dose selection for a direct and selective factor IXa inhibitor and its complementary reversal agent: translating pharmacokinetic and pharmacodynamic properties of the REG1 system to clinical trial design

We performed detailed pharmacokinetic and pharmacodynamic modeling of REG1, an anticoagulation system composed of the direct factor IXa (FIXa) inhibitor pegnivacogin (RB006) and its matched active control agent anivamersen (RB007), with a focus on level of target inhibition to translate phase 1 results to phase 2 dose selection. We modeled early-phase clinical data relating weight-adjusted pegnivacogin dose and plasma concentration to prolongation of the activated partial thromboplastin time (aPTT). Using an in vitro calibration curve, percent FIXa inhibition was determined and related to aPTT prolongation and pegnivacogin dose and concentration. Similar methods were applied to relate anivamersen dose and level of reversal of pegnivacogin anticoagulation. Combined early-phase data suggested that ≥0.75 mg/kg pegnivacogin was associated with >99% inhibition of FIX activity and prolongation of plasma aPTT values ≈2.5 times above baseline, leading to selection of a 1 mg/kg dose for a phase 2a elective percutaneous coronary intervention study to achieve a high intensity of anticoagulation and minimize intersubject variability. Phase 2 validated our predictions, demonstrating 1 mg/kg pegnivacogin yielded plasma concentrations ≈25 μg/ml and >99% inhibition of FIX activity. The relationship between the anivamersen to pegnivacogin dose ratio and degree of pegnivacogin reversal was also validated. Our approach decreased the need for extensive dose-response studies, reducing the duration, complexity and cost of clinical development. The 1 mg/kg pegnivacogin dose and a range of anivamersen dose ratios are being tested in the phase 2b RADAR study (NCT00932100).

Pegnivacogin results in near complete FIX inhibition in acute coronary syndrome patients: RADAR pharmacokinetic and pharmacodynamic substudy

AIMS

Establishing factor IX inhibition in patients with acute coronary syndrome/non-ST-elevation myocardial infarction (ACS/NSTEMI), a setting characterized by increased factor IX activity, is critical to investigate the REG1 system in this target population. The REG1 system (Regado Biosciences, Basking Ridge, NJ) consists of pegnivacogin (RB006), an RNA aptamer that directly inhibits factor IXa, and anivamersen (RB007), its complementary control agent.

METHODS AND RESULTS

RADAR is a Phase 2b study investigating the use of pegnivacogin in patients (n = 800) with ACS undergoing planned early cardiac catheterization. To validate dose selection and stability of anticoagulation throughout the time of cardiac catheterization at an early stage of the clinical trial, 33 patients, 22 of whom had not received recent prior heparin, underwent thorough pharmacokinetic and pharmacodynamic assessment. Fold prolongation of activated partial thromboplastin time (aPTT) was used to impute factor IX inhibition. Pegnivacogin 1 mg/kg rapidly achieved a high pegnivacogin plasma concentration (26.1 ± 4.6 µg/mL), prolonged the aPTT (mean aPTT 93.0 ± 9.5 s), and approached near complete factor IX inhibition (mean fold increase from baseline 2.9 ± 0.3). These levels remained stable from the time of drug administration through completion of the catheterization.

CONCLUSION

Pegnivacogin administered at a weight-adjusted dose of 1 mg/kg consistently achieves a high level of factor IX activity inhibition among patients with ACS and provides stable anticoagulation during cardiac catheterization. These findings support the dose of pegnivacogin selected for the RADAR study.

Translating nucleic acid aptamers to antithrombotic drugs in cardiovascular medicine

Nucleic acid aptamers offer several distinct advantages for the selective inhibition of protein targets within the coagulation cascade. A highly attractive feature of aptamers as antithrombotics is their ability to encode for complementary "controlling agents" which selectively bind to and neutralize their active counterparts via Watson-Crick base pairing or, in a less selective and clinically characterized manner, cationic polymers that can counteract the activity of an aptamer or free/protein-complexed nucleic acid. The former property allows aptamer-based antithrombotic therapies to be administered with a goal of selective, high intensity target inhibition, knowing that rapid drug reversal is readily available. In addition, by purposefully varying the ratio of active agent to a specific controlling agent administered, the intensity of antithrombotic therapy can be regulated with precision according to patient needs and the accompanying clinical conditions. REG1, currently undergoing phase 2B clinical investigation, consists of an RNA aptamer (RB006; pegnivacogin) which targets factor IXa and its complementary controlling agent (RB007; anivamersen). Aptamers directed against other serine coagulation proteases, some with and some without parallel controlling agents, have been designed. Aptamers directed against platelet surface membrane receptor targets are in preclinical development. The following review offers a contemporary summary of nucleic acid aptamers as a translatable platform for regulatable antithrombotic drugs expanding the paradigm of patient- and disease-specific treatment in clinical practice.

Pathogenesis of Sudden Unexpected Death in a Clinical Trial of Patients With Myocardial Infarction and Left Ventricular Dysfunction, Heart Failure, or Both

Background— The frequency of sudden unexpected death is highest in the early post–myocardial infarction (MI) period; nevertheless, 2 recent trials showed no improvement in mortality with early placement of an implantable cardioverter-defibrillator after MI.

Methods and Results— To better understand the pathophysiological events that lead to sudden death after MI, we assessed autopsy records in a series of cases classified as sudden death events in patients from the VALsartan In Acute myocardial infarctioN Trial (VALIANT). Autopsy records were available in 398 cases (14% of deaths). We determined that 105 patients had clinical circumstances consistent with sudden death. On the basis of the autopsy findings, we assessed the probable cause of sudden death and evaluated how these causes varied with time after MI. Of 105 deaths considered sudden on clinical grounds, autopsy suggested the following causes: 3 index MIs in the first 7 days (2.9%); 28 recurrent MIs (26.6%); 13 cardiac ruptures (12.4%); 4 pump failures (3.8%); 2 other cardiovascular causes (stroke or pulmonary embolism; 1.9%); and 1 noncardiovascular cause (1%). Fifty-four cases (51.4%) had no acute specific autopsy evidence other than the index MI and were thus presumed arrhythmic. The percentage of sudden death due to recurrent MI or rupture was highest in the first month after the index MI. By contrast, after 3 months, the percentage of presumed arrhythmic death was higher than recurrent MI or rupture (χ 2 =23.3, P <0.0001).

Conclusions— Recurrent MI or cardiac rupture accounts for a high proportion of sudden death in the early period after acute MI, whereas arrhythmic death may be more likely subsequently. These findings may help explain the lack of benefit of early implantable cardioverter-defibrillator therapy.

Coagulation factor IXa as a target for treatment and prophylaxis of venous thromboembolism

Venous thromboembolism remains a frequent cause of vascular death. Despite advances in anticoagulant drug development, unmet needs remain, including limited treatment options for patients with severe renal impairment and the inability to fully reverse the effects of anticoagulants approved or in late-stage development. Because coagulation factor IXa plays a pivotal role in tissue factor-mediated thrombin generation, it represents an attractive target for anticoagulant development. This article discusses the rationale for factor IXa as an anticoagulant target and the potential role in venous thromboembolism prevention or management of the 2 factor IXa inhibitors that have undergone testing in phase 1 or 2 trials: TTP889, an oral, small-molecule compound, and RB006, an aptamer-based compound, the intravenous and subcutaneous formulations of which are the anticoagulant components of the REG1 and REG2 anticoagulation systems, respectively.

Time-limited efficacy of pacing electrodes following open heart surgery

Temporary epicardial pacing electrodes have been utilised since the 1960s in the postoperative management of cardiac surgical patients, both as a diagnostic tool and therapeutic intervention. To determine the efficacy of the epicardial pacing wires over time after open heart surgery, 30 patients (20M/10F) who underwent coronary artery bypass surgery, were evaluated by standard 12-lead EKG, atrial electrogram, and atrial and ventricular pacing thresholds immediately after surgery and on postoperative day 5. Both atrial and ventricular pacing thresholds were significantly increased on postoperative day 5 as compared to baseline. The ability for effective AAI, VVI and DDD pacing was lost in 38.89 percent, 37.5 percent and 61.11 percent of patients, respectively, on postoperative day 5. We conclude that both atrial and ventricular pacing wires have limited efficacy after postoperative day 4 for pacing after open heart surgery due to a marked increase in pacing thresholds over this time period.

The relationship of anticoagulation level and complications after successful percutaneous transluminal coronary angioplasty

The degree of anticoagulation and its effect on the frequency of abrupt coronary artery closure, coronary ischemia, bleeding complications requiring transfusion, and death were examined in 336 patients after elective percutaneous transluminal coronary angioplasty (PTCA). All patients received a bolus of 10,000 U of heparin at the beginning of the procedure followed by a continuous infusion of 2000 U/hr. At the conclusion of the procedure the infusion was reduced to 1000 U/hr and continued for 18 to 24 hours at which time the heparin infusion was suspended to allow removal of arterial and venous access sheaths. Partial thromboplastin time (PTT) was examined while patients continued to receive the heparin infusion. There was a variable degree of PTT prolongation in response to a standard dose of heparin with a range of 34 seconds to "greater than 150 seconds." Patients were divided into two groups according to the degree of heparin-induced PTT prolongation: group A included 271 patients with PTT greater than or equal to 3 times the control value, and group B comprised 65 patients with PTT less than 3 times the control value. Ischemic complications were analyzed on day 1 after PTCA and at hospital discharge. Bleeding complications and mortality were examined only at hospital discharge. There was a significant reduction in the incidence of abrupt coronary artery closure in group A on day 1 (1.5% vs 10.7%, p less than 0.001) and at hospital discharge (2.6% vs 10.7%, p less than 0.003).(ABSTRACT TRUNCATED AT 250 WORDS)