Abciximab. An updated review of its use in ischaemic heart disease

Past, Present and (Foreseeable) Future of Biological Anti-TNF Alpha Therapy

Due to the key role of tumor necrosis factor-alpha (TNF-α) in the pathogenesis of immunoinflammatory diseases, TNF-α inhibitors have been successfully developed and used in the clinical treatment of autoimmune disorders. Currently, five anti-TNF-α drugs have been approved: infliximab, adalimumab, golimumab, certolizumab pegol and etanercept. Anti-TNF-α biosimilars are also available for clinical use. Here, we will review the historical development as well as the present and potential future applications of anti-TNF-α therapies, which have led to major improvements for patients with several autoimmune diseases, such as rheumatoid arthritis (RA), ankylosing spondylitis (AS), Crohn's disease (CD), ulcerative colitis (UC), psoriasis (PS) and chronic endogenous uveitis. Other therapeutic areas are under evaluation, including viral infections, e.g., COVID-19, as well as chronic neuropsychiatric disorders and certain forms of cancer. The search for biomarkers able to predict responsiveness to anti-TNF-α drugs is also discussed.

High-Throughput Monoclonal Antibody Discovery from Phage Libraries: Challenging the Current Preclinical Pipeline to Keep the Pace with the Increasing mAb Demand

Simple Summary

Monoclonal antibodies are increasingly used for a broad range of diseases. Rising demand must face with time time-consuming and laborious processes to isolate novel monoclonal antibodies. Next-generation sequencing coupled to phage display provides timely and sustainable high throughput selection strategy to rapidly access novel target. Here, we describe the current NGS-guided strategies to identify potential binders from enriched sub-libraires by applying a user-friendly informatic pipeline to identify and discard false positive clones. Rescue step and strategies to boost mAb yield are also discussed to improve the limiting selection and screening steps.

Abstract

Monoclonal antibodies are among the most powerful therapeutics in modern medicine. Since the approval of the first therapeutic antibody in 1986, monoclonal antibodies keep holding great expectations for application in a range of clinical indications, highlighting the need to provide timely and sustainable access to powerful screening options. However, their application in the past has been limited by time-consuming and expensive steps of discovery and production. The screening of antibody repertoires is a laborious step; however, the implementation of next-generation sequencing-guided screening of single-chain antibody fragments has now largely overcome this issue. This review provides a detailed overview of the current strategies for the identification of monoclonal antibodies from phage display-based libraries. We also discuss the challenges and the possible solutions to improve the limiting selection and screening steps, in order to keep pace with the increasing demand for monoclonal antibodies.

A Patent Review on the Therapeutic Application of Monoclonal Antibodies in COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) contains spike proteins that assist the virus in entering host cells. In the absence of a specific intervention, efforts are afoot throughout the world to find an effective treatment for SARS-CoV-2. Through innovative techniques, monoclonal antibodies (MAbs) are being designed and developed to block a particular pathway of SARS-CoV-2 infection. More than 100 patent applications describing the development of MAbs and their application against SARS-CoV-2 have been registered. Most of them target the receptor binding protein so that the interaction between virus and host cell can be prevented. A few monoclonal antibodies are also being patented for the diagnosis of SARS-CoV-2. Some of them, like Regeneron^® have already received emergency use authorization. These protein molecules are currently preferred for high-risk patients such as those over 65 years old with compromised immunity and those with metabolic disorders such as obesity. Being highly specific in action, monoclonal antibodies offer one of the most appropriate interventions for both the prevention and treatment of SARS-CoV-2. Technological advancement has helped in producing highly efficacious MAbs. However, these agents are known to induce immunogenic and non-immunogenic reactions. More research and testing are required to establish the suitability of administering MAbs to all patients at risk of developing a severe illness. This patent study is focused on MAbs as a therapeutic option for treating COVID-19, as well as their invention, patenting information, and key characteristics.

Monoclonal antibody based radiopharmaceuticals for imaging and therapy

The concept of personalized medicine has been steadily growing for the past decades. Monoclonal antibodies (mAbs) are undoubtedly playing an important role in the transition away from conventional medical practice to a more tailored approach to deliver the best therapy with the highest safety margin to a specific patient. In certain instances, mAbs and antibody drug conjugates (ADCs) may represent the preferred therapeutic option for several types of cancers due to their high specificity and affinity to the antigen. Monoclonal antibodies can be labeled with specific radionuclides well-suited for PET (Positron Emission Tomography) or gamma camera scintigraphy. The use of radiolabeled mAbs allows the interrogation of specific biomarkers and assessment of tumor heterogeneity in vivo by a single diagnostic imaging scan that includes the whole-body in the field-of-view. Moreover, the same mAb can then be radiolabeled with an analogous radionuclide for the delivery of beta-minus radiation or alpha-particles as part of a radioimmunotherapy (RIT) approach. However, the path to develop, validate, and implement mAb-based radiopharmaceuticals from bench-to-bedside is complex due to the extensive pre-clinical experiments and toxicological studies required, and the necessity of labor-intensive clinical trials that often require multi-time-point imaging and blood draws for internal radiation dosimetry and pharmacokinetics. As more mAb-based radiopharmaceuticals have been developed and evaluated, the opportunities and limitations offered by mAbs have become better defined. Our aim with this manuscript is therefore to provide an overview of the recent advances in the development of mAb-based radiopharmaceuticals and their clinical applications in Oncology.

Biologic Therapy and Severe Asthma in Children

Severe asthma is a heterogeneous, complex and chronic disease widespread in the pediatric population. According to the recent findings about the different endotypes of asthma in children, each one characterized by specific intracellular molecular pathways, several innovative biologic therapies have been developed. Due to their precise ability to target specific inflammatory type 2 mediators, biologics have revolutionized the care of chronic allergic diseases in the pediatric and adult population. In this review, we aim to provide the latest evidence about the use, indications, efficacy and safety of biologic therapies to treat severe asthma in children and adolescents.

Role of immunoglobulin and antibodies in disease management

The immune system is a highly advanced and coordinated mechanism that allows a living organism to distinguish between "self" and "non-self". The host uses both innate and adaptive immune response mechanisms to identify and eliminate pathogenic microorganisms. Human immunoglobulin is the prominently used blood product in the clinical practice. Immunoglobulin applications have improved rapidly due to the exploration of its immunomodulatory and anti-inflammatory properties. This made this blood product into a precious and advanced tool in the treatment of numerous disease conditions which are linked with humoral immune deficiency or that cause immune system dysfunction. Human immunoglobulin (Ig) is used for Ig replacement therapy in both primary and secondary immunodeficiency conditions, for prevention and treatment of certain infections. It also acts as an immunomodulatory agent for autoimmune and inflammatory disorders. Therapeutic antibodies have been successfully used for the treatment of diverse pathological conditions. Drug development programs exclusively select highly specific antibodies that recognize a single disease-associated target. Hopefully this review will give an insight towards the immune system, the involvement of the specialized immune cells, their products and involvement in various immune disorders and pathological conditions.

Development of therapeutic antibodies for the treatment of diseases

It has been more than three decades since the first monoclonal antibody was approved by the United States Food and Drug Administration (US FDA) in 1986, and during this time, antibody engineering has dramatically evolved. Current antibody drugs have increasingly fewer adverse effects due to their high specificity. As a result, therapeutic antibodies have become the predominant class of new drugs developed in recent years. Over the past five years, antibodies have become the best-selling drugs in the pharmaceutical market, and in 2018, eight of the top ten bestselling drugs worldwide were biologics. The global therapeutic monoclonal antibody market was valued at approximately US$115.2 billion in 2018 and is expected to generate revenue of $150 billion by the end of 2019 and $300 billion by 2025. Thus, the market for therapeutic antibody drugs has experienced explosive growth as new drugs have been approved for treating various human diseases, including many cancers, autoimmune, metabolic and infectious diseases. As of December 2019, 79 therapeutic mAbs have been approved by the US FDA, but there is still significant growth potential. This review summarizes the latest market trends and outlines the preeminent antibody engineering technologies used in the development of therapeutic antibody drugs, such as humanization of monoclonal antibodies, phage display, the human antibody mouse, single B cell antibody technology, and affinity maturation. Finally, future applications and perspectives are also discussed.

Eptifibatide is associated with significant cost savings and similar clinical outcomes to abciximab when used during primary percutaneous coronary intervention for ST-elevation myocardial infarction: An observational cohort study of 3863 patients

INTRODUCTION

Glycoprotein IIb/IIIa inhibitors are recommended by guidelines in patients with ST-segment elevation myocardial infarction treated with primary percutaneous coronary intervention. There are few studies directly comparing these agents. The aim of this study was to assess whether eptifibatide is a safe and cost-effective alternative to abciximab in the treatment of primary percutaneous coronary intervention for ST-segment elevation myocardial infarction.

METHODS

This was an observational cohort study of 3863 patients who received a GPIIb/IIIa inhibitor whilst undergoing primary percutaneous coronary intervention from 2007 to 2014. Patients who did not receive a GPIIb/IIIa inhibitor were excluded. Time to first major adverse cardiac event defined as death, non-fatal myocardial infarction, stroke or target vessel revascularization, and total hospital costs were compared between the groups.

RESULTS

In all, 1741 patients received abciximab with 2122 receiving eptifibatide. Patients who received eptifibatide had higher rates of previous MI/percutaneous coronary intervention and were more likely to undergo a procedure from the radial route. Unadjusted Kaplan-Meier analysis revealed no significant difference in the 1-year event rates between patients given eptifibatide versus abciximab (p = 0.201). Age-adjusted Cox analysis demonstrated no difference in 1-year outcome between abciximab and eptifibatide (hazard ratio: 0.83; 95% confidence interval: 0.73-1.39), which persisted after multivariate adjustment (hazard ratio: 0.92; 95% confidence interval: 0.79-1.56) including the incorporation of a propensity score (hazard ratio: 0.88; 95% confidence interval: 0.71-1.44). Eptifbatide was associated with significant cost savings being 87% cheaper overall compared to abciximab (on average £650 cheaper per patient and saving approximately £950,000).

CONCLUSION

This observational data suggest that eptifibatide is associated with similar outcomes and significant cost savings compared to abciximab when used in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention.

Management of coronary artery aneurysms using abciximab in children with Kawasaki disease

INTRODUCTION

There are limited data regarding the possible benefits of abciximab in children with Kawasaki disease (KD), who developed serious cardiac abnormalities non-responsive to standard treatment.

MATERIALS AND METHODS

We retrospectively identified children with KD who were treated with abciximab from 2007 to 2015. Data regarding clinical course, treatment, echocardiographic data and follow-up at 1 and 6months were retrieved.

RESULTS

During the study period, fifteen children were identified who were diagnosed with KD and were given abciximab. The median age at onset of symptoms was 11months (range: 2months-6years). The median day of disease at admission was 10days (range: 4-26days) and the median day of administration of abciximab was 17days (range: 9-40). Twelve children were diagnosed with complete and three with incomplete KD. Aneurysms were found in 8 children: 2 had ectatic coronary arteries and 5 presented with both ectasia and aneurysms. At 1month follow-up, echocardiographic findings showed regression in the size of aneurysms in 11 children, resolution of the aneurysms or ectasia of coronary arteries in 3 children, while one child who could not take aspirin because of G6PD deficiency died. After 6months of follow-up, echocardiographic findings showed resolution of coronary abnormalities in 12 (80%) children, whereas 2 children (13.3%) presented with significant regression of aneurysms.

CONCLUSIONS

Abciximab may have an important role in the management of severe cardiac complications of KD, although prospective randomized controlled studies are needed to fully evaluate its role.

Management of acute and refractory Kawasaki disease

Acute Kawasaki disease (KD) is treated with high-dose intravenous immunoglobulin (IVIG), which is proven to decrease the incidence of coronary artery aneurysms from 25% to less than 5%. Aspirin is also given, although the evidence base is less secure. There is increasing evidence for steroid therapy as adjunctive primary therapy with IVIG, especially in Asian children. Approximately 10-30% of patients fail to respond to the initial IVIG and are at increased risk of coronary artery aneurysms. The optimal treatment for IVIG-nonresponsive KD remains controversial. Management options include further dose(s) of IVIG, corticosteroids, TNF-α blockade, cyclosporin A, anti-IL-1 and anti-CD20 therapy. In this article, the authors review the current evidence for treatment of acute KD and discuss options for IVIG nonresponders.

Does abciximab promote coronary artery remodeling in patients with Kawasaki disease?

Standard therapy, consisting of intravenous immunoglobulin and aspirin, reduces, but does not eliminate, coronary artery aneurysms (CAAs) in patients with Kawasaki disease. Large CAAs can persist or undergo varying degrees of regression. The treatment of large CAAs using abciximab has been associated with short-term regression; however, longer term data are unavailable. We sought to obtain longer term follow-up data regarding the changes in the diameters of large CAAs in patients receiving both abciximab and standard therapy and to compare these changes to those of a similar group receiving standard therapy alone. All patients with Kawasaki disease and large CAAs (diameter >5 mm or Z score >10) treated from 1986 to 2007 were identified and divided into 2 groups. The abciximab group received abciximab plus standard therapy and the no-abciximab group received standard therapy alone. The maximum diameters of the proximal right and left anterior descending CAAs were obtained from echocardiograms. The Z scores were calculated for 3 points: the acute/subacute phase (<8 weeks) and at 1 and 3 to 5 years of follow-up. The patients in the abciximab (n = 11) and no-abciximab (n = 7) groups were similar in age, interval to treatment, gender, and largest CAA Z score at diagnosis (19.6 +/- 6.2 vs 25.8 +/- 9.5, p = 0.11). The change in CAA Z score was similar between the 2 groups at 1 year (p = 0.99). At 3 to 5 years of follow-up, compared to baseline, the abciximab group had a greater decrease in the CAA Z score than did the no-abciximab group (-14.0 +/- 4.0 vs -8.2 +/- 5.9, p = 0.04). In conclusion, abciximab treatment might be associated with vascular remodeling in patients with large CAAs.

Molecular Biology of Apoptosis in Ischemia and Reperfusion

This study reviews the current understanding of the mechanisms that mediate the complex processes involved in apoptosis secondary to ischemia and reperfusion (I/R) and is not intended as a complete literature review of apoptosis. Several biochemical reactions trigger a cascade of events, which activate caspases. These caspases exert their effect through downstream proteolysis until the final effector caspases mediate the nuclear features characteristic of apoptosis, DNA fragmentation and condensation. Within the context of ischemia, the hypoxic environment initiates the expression of several genes involved in inflammation, the immune response, and apoptosis. Many of these same genes are activated during reperfusion injury in response to radical oxygen species generation. It is plausible that inhibition of specific apoptotic pathways via inactivation or downregulation of those genes responsible for the initiation of inflammation, immune response, and apoptosis may provide promising molecular targets for ameliorating reperfusion injury in I/R-related processes. Such inhibitory mechanisms are discussed in this review. Important targets in I/R-related pathologies include the brain during stroke, the heart during myocardial infarction, and the organs during harvesting and/or storage for transplantation. In addition, we present data from our ongoing research of specific signal transduction-related elements and their role in ischemia/reperfusion injury. These data address the potential therapeutic application of anti-inflammatory and anti-ischemic compounds in the prevention of I/R damage.

The evolution of thrombolytic therapy and adjunctive antithrombotic regimens in acute ST-segment elevation myocardial infarction

Acute ST-segment elevation myocardial infarction continues to be associated with substantial mortality rates. Despite much advancement in care, current treatments have also failed to eliminate the significant risk of morbidity, including reinfarction, reocclusion of the infarct-related artery, and thromboembolic stroke. The potential benefit of early thrombolytic therapy in reducing mortality was first established in 1986. Further benefits of conjunctive therapy with aspirin were demonstrated soon thereafter. This review examines the most significant trends in the pharmacologic therapy of ST-segment elevation myocardial infarction since the publication of these early studies: the development of fibrinolytic drugs with improved clot selectivity and improved pharmacokinetic profiles that simplify administration, making ED or even prehospital thrombolysis more practical. More recent data can be interpreted as showing that regimens that are simpler and easier to administer are also clinically superior. This article reviews pharmacologic advances and evaluates the evidence for their use in EDs.

Abciximab: an updated review of its therapeutic use in patients with ischaemic heart disease undergoing percutaneous coronary revascularisation

Abciximab (Reopro) is an antibody fragment that dose-dependently inhibits platelet aggregation and leucocyte adhesion by binding to the glycoprotein (GP) IIb/IIIa, vitronectin and Mac-1 receptors. Abciximab (0.25 mg/kg bolus plus infusion of 0.125 micro g/kg/min for 12 hours) showed greater efficacy than tirofiban in reducing the 30-day composite endpoint of death, nonfatal myocardial infarction (MI) or urgent target-vessel revascularisation in the randomised, double-blind TARGET study in patients scheduled for stent placement. In addition, the beneficial effects of treatment with abciximab previously observed in the randomised, multicentre, placebo-controlled EPILOG and EPISTENT studies have been maintained to 1 year, with a significantly reduced incidence of ischaemic complications relative to placebo consistently observed across a range of subgroups including age, sex, bodyweight and indication for revascularisation. The incidence of the composite endpoint was reduced in patients presenting with acute MI of <48 hours' duration in comparison with either fibrinolytic therapy or stenting alone in the randomised STOPAMI and ADMIRAL trials, primarily because of a reduced requirement for urgent repeat revascularisation and reduced incidence of mortality. In the randomised, nonblind, multicentre CADILLAC trial in patients with acute myocardial infarction (MI), stenting alone was superior to percutaneous transluminal coronary angioplasty (PTCA) and stenting alone was not inferior to PTCA plus abciximab. Recent large randomised, multicentre studies (ASSENT-3 and GUSTO-V) have shown higher efficacy (on various ischaemic endpoints) of abciximab in combination with either a reduced dose of tenecteplase or reteplase compared with the fibrinolytic drug alone. TIMI grade 3 flow rates at 60 and 90 minutes in the TIMI-14 and SPEED trials were higher in patients who received abciximab in combination with either alteplase or reteplase than abciximab alone and were similar to that seen with the full-dose fibrinolytic alone. In the randomised, multicentre GUSTO IV-ACS study, no significant differences in any of the ischaemic endpoints at either 7 or 30 days in patients with acute coronary syndromes who were not scheduled to undergo early revascularisation (within 12 hours of end of infusion) were apparent between those who received abciximab (bolus and either 24- or 48-hour infusion) and those who received placebo in addition to aspirin and heparin. The most common adverse events associated with the use of abciximab are bleeding complications and thrombocytopenia, although the risk of major bleeding can be limited through adhering to current administration protocols. Treatment costs are generally higher in both stent plus abciximab and angioplasty plus abciximab groups than stent plus placebo, primarily because of the acquisition cost of abciximab. Abciximab appeared most cost beneficial in high-risk patients undergoing elective percutaneous coronary revascularisation; among lower risk patients, abciximab therapy has been associated with higher total in-hospital and 6-month medical costs than eptifibatide.

CONCLUSION

The GP IIb/IIIa receptor antagonist abciximab, when used with aspirin and heparin, has demonstrated efficacy in reducing the short- and long-term risk of ischaemic complications in patients with ischaemic heart disease undergoing percutaneous coronary intervention, when used with aspirin and heparin. High-risk patients (including those with diabetes mellitus) derive particular benefits from abciximab treatment. Abciximab remains an important therapeutic option for the prevention of complications in patients with ischaemic heart disease.

The role of low-molecular-weight heparin in the management of acute coronary syndromes

A substantial number of clinical studies have consistently demonstrated that low-molecular-weight heparin (LMWH) compounds are effective and safe alternative anticoagulants to unfractionated heparins (UFHs). They have been found to improve clinical outcomes in acute coronary syndromes and to provide a more predictable therapeutic response, longer and more stable anticoagulation, and a lower incidence of UFH-induced thrombocytopenia. Of the several LMWH agents that have been studied in large clinical trials, including enoxaparin, dalteparin, and nadroparin, not all have shown better efficacy than UFH. Enoxaparin is the only LMWH compound to have demonstrated sustained clinical and economic benefits in comparison with UFH in the management of unstable angina/ non-ST-segment elevation myocardial infarction (NSTEMI). Also, LMWH appears to be a reliable and effective antithrombotic treatment as adjunctive therapy in patients undergoing percutaneous coronary intervention. Clinical trials with enoxaparin indicate that LMWH is effective and safe in this indication, with or without the addition of a glycoprotein IIb/IIIa inhibitor. The efficacy demonstrated by enoxaparin in improving clinical outcomes in unstable angina/NSTEMI patients has led to investigations of its role in the management of ST-segment elevation myocardial infarction. Initial results are very encouraging, and they indicate that enoxaparin may potentially substitute for UFH as adjunctive therapy in fibrin-specific thrombolytic regimens and improve coronary reperfusion rates in streptokinase-based regimens.

Early recovery of microvascular perfusion induced by t-PA in combination with abciximab or eptifibatide during postischemic reperfusion

BACKGROUND

GPIIb/IIIa inhibitors abciximab and eptifibatide have been shown to inhibit platelet aggregation in ischemic heart disease. Our aim was to test the efficacy of abiciximab (Reo Pro) or eptifibatide (Integrilin) alone or in combination with plasminogen activator (t-PA) in an experimental model of ischemia reperfusion (I/R) in hamster cheek pouch microcirculation visualized by fluorescence microscopy. Hamsters were treated with saline, or abiciximab or eptifibatide or these drugs combined with t-PA infused intravenously 10 minutes before ischemia and through reperfusion. We measured the microvessel diameter changes, the arteriolar red blood cell (RBC) velocity, the increase in permeability, the perfused capillary length (PCL), and the platelet and leukocyte adhesion on microvessels.

RESULTS

I/R elicited large increases in the platelet and leukocyte adhesion and a decrease in microvascular perfusion. These responses were significantly attenuated by abiciximab or eptifibatide (PCL:70 and 65% at 5-10 mins of reperfusion and 85 and 87% at 30 mins of reperfusion, respectively, p < 0.001) while t-PA combined with abiciximab or eptifibatide, was more effective and microvascular perfusion recovered immediately after postischemic reperfusion.

CONCLUSIONS

Platelets are crucial in I/R injury, as shown by the treatment with abicixmab or eptifibatide, which decreased platelet aggregation in microvessels, and also decreased leukocyte adhesion in venules. Arterial vasoconstriction, decreased arterial RBC velocity and alterations in the endothelial barrier with increased permeability delayed the complete restoration of blood flow, while t-PA combined with inhibition of platelet aggregation speeded up the capillary perfusion after reperfusion.

Variability in abciximab (ReoPro) prescribing: evidence based or budget driven?

PURPOSE

Abciximab improves outcomes in patients undergoing percutaneous transluminal coronary intervention (PTCA). Clinicians, however, have expressed concerns that they do not have enough budget to administer abciximab to all eligible patients. We studied the patterns of prescribing of abciximab and identified factors that correlate with the level of usage.

METHODS

In each of all 13 Dutch PTCA centres one opinion-leading cardiologist was approached to provide data on the abciximab prescribing in their centre and to co-operate in an interview on this topic. We performed linear regression analysis in which the level of abciximab prescribing was the dependent variable. Potential determinants investigated were the number of PTCAs performed, the criteria for abciximab prescribing, funding and possible financial restrictions, participation in clinical trials in the past, percentage stenting, and desired level of abciximab prescribing.

RESULTS

All 13 PTCA centres in the Netherlands participated in our study. The level of abciximab prescribing varied from 2 to 36% of all PTCAs. The criteria for patient selection significantly differed between centres. Together budget, investigatorship, size, and type of the institution were highly predictive for the level of abciximab prescribing (R2 = 0.93, p < 0.001). The more patients doctors had included in clinical trials in the past, the higher was the likelihood that they had prescribed abciximab.

CONCLUSIONS

Shortly after its introduction, patterns of abciximab prescribing varied widely between PTCA centres. There was no agreement on which patients to select for this preventive treatment. Budget and involvement in clinical trials in the past were important predictors of the level of prescribing in each centre.

Does Abciximab enhance regression of coronary aneurysms resulting from Kawasaki disease?

OBJECTIVE

Acute Kawasaki disease can result in the development of large coronary artery aneurysms that may persist. Abciximab, a platelet glycoprotein IIb/IIIa receptor inhibitor, is associated with resolution of thrombi and vascular remodeling in adults with acute coronary syndromes. The purpose of this study was to compare changes in aneurysm diameter at early follow-up in patients who had Kawasaki disease and received abciximab in addition to standard therapy with those who were treated with standard therapy alone.

METHODS

Patients with Kawasaki disease and large aneurysms were divided into 2 groups on the basis of acute therapy: 1) abciximab in addition to standard therapy and 2) standard therapy alone. Echocardiograms were reviewed for coronary aneurysms (lumen diameter 1.5 times that of the adjacent vessel). Maximum aneurysm diameter was determined during the acute/subacute phase of Kawasaki disease (<6 weeks) and at early follow-up (4-6 months). Regression of the aneurysm was defined as a decrease in lumen diameter, and resolution was defined as normalization of the vessel.

RESULTS

Six patients had 20 aneurysms in the abciximab group, and 9 patients had 30 aneurysms in the standard therapy group. Early follow-up data were available for 19 of the 20 aneurysms in the abciximab group and 19 of the 30 aneurysms in the standard therapy group. Patients who were treated with abciximab demonstrated greater regression in aneurysm size at early follow-up than patients who were treated with standard therapy alone (percentage decrease: 41 +/- 19% vs 17 +/- 27%). In the abciximab group, 68% (13 of 19) of aneurysms resolved at early follow-up compared with 35% (7 of 19) in the standard therapy group.

CONCLUSIONS

Patients who were treated with abciximab demonstrated greater regression in aneurysm diameter at early follow-up than patients who received standard therapy alone. These findings suggest that treatment with abciximab may promote vascular remodeling in this population and warrants further study.

[Variable response to the biological inhibition of platelets by abciximab in patients subjected to percutaneous coronary angioplasty]

INTRODUCTION AND OBJECTIVES

Abciximab has been shown to reduce the risk of thrombotic complications during coronary angioplasty, however there are still many aspects to be resolved. The aim of this study was to investigate the various biological effects of abciximab on platelets during coronary angioplasty.

METHODS

The degree of platelet inhibition (with 5 and 20 mol/l concentrations of ADP), occlusion time (measurement of platelet haemostatic capacity, PFA-100), and the platelet activation markers were determined in 15 patients who underwent basal coronary angioplasty and abciximab treatment. Determinations were obtained before, 15 minutes after procedure initiation, at procedure termination, and 24 hours after procedure termination.

RESULTS

More than 80% platelet aggregation inhibition was observed in 13 patients during the procedure, but after 24 hours (p < 0.05) was only detected in two. The occlusion time during the procedure was > 300 sec. in 13 patients, 6 of whom evolved to normal values after 24 hours (p < 0.05). A high correlation (p = 0.02) was found between these two parameters during the intervention, but not after 24 hours. No platelet inhibition or occlusion time changes were observed in 2 patients during the study. The expression of p-selectin increased significantly during the procedure (p < 0.05).

CONCLUSIONS

The variability of platelet function inhibition and existence of circulating activation during coronary angioplasty following the administration of abciximab support the use of early analytical controls with the objective of modifying guidelines for use in order to optimize its effect or to combine it with other antithrombotic agents.

A review of modifications to recombinant antibodies: attempt to increase efficacy in oncology applications

Although monoclonal antibodies have high specificity, their usefulness in the clinic, especially against solid tumors, has been limited. This arises in part from the inability of antibody molecules to penetrate into the tumor and kill the tumor cells. In addition, natural cytotoxic effects of antibodies, mediated through complement or Fc receptors, may not be sufficient to kill malignant cells. This review will present some of the antibody modifications used to increase efficacy. Modified recombinant antibodies have been designed to be more cytotoxic (immunotoxins), to increase natural effector functions (bivalent antibodies, antibody-fusion molecules, multimeric antibodies, directed mutations in Fc region), or to pretarget cells for concentration of cytotoxic drugs. This review will also focus on engineering of smaller versions of antibodies that retain specificity (single chain Fvs, Fabs, Fab(2)s, minibodies, domain deleted antibodies) and have increased penetrability of solid tumors. Many of these antibody modifications may result in antigenic compounds which can limit repeat administration. Clinical experiences will be highlighted if information is available.

Differential inhibition of adenosine diphosphate- versus thrombin receptor-activating peptide-stimulated platelet fibrinogen binding by abciximab due to different glycoprotein IIb/IIIa activation kinetics

The exposure of internal glycoprotein (GP) IIb/IIIa receptors has been proposed to explain the incomplete inhibition of aggregation of thrombin receptor-activating peptide (TRAP)-stimulated platelets by abciximab. However, a marked and rapid externalization of GPIIb/IIIa was also observed upon stimulation with 30 microM adenosine diphosphate (ADP). ADP-induced fibrinogen binding was completely inhibited by 10 microg/mL abciximab, 30 nM tirofiban, or 3 microg/mL eptifibatide, while fibrinogen binding induced by 100 microM TRAP was inhibited only by 50%. Interestingly, striking differences in fibrinogen binding kinetics in ADP- versus TRAP-stimulated platelets were observed. ADP-induced fibrinogen binding was much slower than that of abciximab. These differences in the fibrinogen binding rate were due to differential GPIIb/IIIa activation kinetics because the actual fibrinogen binding rate (measured by adding fibrinogen after platelet activation) was similar in ADP- and TRAP-stimulated platelets. Thus, the TRAP-induced GPIIb/IIIa activation rate would allow significant amounts of fibrinogen to occupy externalized GPIIb/IIIa receptors even in the presence of the inhibitor.

GENERAL PHARMACOLOGIC TREATMENT OF ACUTE MYOCARDIAL INFARCTION

The general pharmacotherapeutic issues surrounding AMI are complex and expanding, especially with regard to treatment aimed at the [table: see text] culprit, coronary atherosclerotic thrombus. Basic, well-established therapy includes the routine administration of oxygen, nitroglycerin, aspirin, and at times morphine, with selected cases invoking caution with respect to these agents (e.g., nitroglycerin and the risk of hypotension in right ventricular infarction; contraindication to nitrolycerin in patients on sildenafil). Cardioprotective agents, especially beta-adrenergic antagonists, should be considered early in light of their demonstrated benefit; others, such as ACE inhibitors, need not be administered in the ED. Heparin, both UFH and the newer LMWHs, have well-established roles in acute coronary syndromes. The GP IIb/IIIa inhibitors are the most recent addition to the pharmacologic armamentarium; their role is evolving rapidly as research on this frontier continues. Table 2 reviews recommended dosing of selected agents in acute coronary syndromes.

The use of glycoprotein IIb/IIIa inhibitors in patients with coronary artery disease

Platelet membrane glycoprotein IIb/IIIa inhibitors, a new class of potent antiplatelet agents, have been used in the treatment of acute coronary syndromes as well as in the prevention of complications after percutaneous coronary interventions. Approximately 50,000 patients with coronary artery disease have been enrolled in randomized studies of glycoprotein IIb/IIIa inhibitors. The purpose of this article is to review the pharmacology of glycoprotein IIb/IIIa inhibitors, the results of the clinical trials using these agents, and their current use in percutaneous coronary interventions and the treatment of acute coronary syndromes.

Platelet kinetics in dogs treated with a glycoprotein IIb/IIIa peptide antagonist

Platelet glycoprotein IIb/IIIa (GPIIb/IIIa) receptor antagonists have been highly effective inhibitors of platelet aggregation in preclinical studies and in clinical trials. However, decreased platelet counts have been documented in preclinical studies and in some patients receiving GPIIb/IIIa antagonists. We evaluated changes in platelet kinetics and fate in dogs receiving the GPIIb/IIIa receptor antagonist RPR 109891 orally for 4 days. Dogs receiving RPR 109891 had a 22-52% decrease in platelet count with the nadirs at 3-5 days after initiation of treatment. Platelet survival time was reduced by 19%, and platelet half-life was reduced by 63%. Indium-111-labeled platelets were rapidly cleared from the blood within 1 hour after administration of RPR 109891 on treatment days 1 and 2. This clearing was associated with a sharp increase in radioactivity in spleen but not in liver or lung. Platelet clearance was markedly attenuated on treatment days 3 and 4. Platelet counts returned to baseline within 1 week after discontinuation of treatment. These data indicate that RPR 109891 causes rapid and selective sequestration of platelets in the spleen.