Aspirin at 120: Retiring, recombining, or repurposing?

Drug repurposing: Clinical practices and regulatory pathways

Drug repurposing, also known as drug repositioning or reprofiling, involves identifying new therapeutic uses for existing drugs beyond their original indications. Historical examples include sildenafil citrate transitioning to an erectile dysfunction treatment and thalidomide shifting from a sedative to an immunomodulatory agent. Advocates tout its potential to address unmet medical needs by expediting development, reducing costs, and using drugs with established safety profiles. However, concerns exist regarding specificity for new indications, safety, and regulatory exploitation. Ethical considerations include equitable access, informed consent when using drugs off-label, and transparency. Recent advancements include artificial intelligence (AI) applications, network pharmacology, and omics technologies. Clinical trials explore repurposed drugs' efficacy, with regulatory agencies facilitating approval. Challenges include intellectual property protection, drug target specificity, trial design complexities, and funding limitations. Ethical challenges encompass patient autonomy, potential conflicts of interest due to financial incentives for industries, and resource allocation. Future directions involve precision medicine, AI, and global collaboration. In conclusion, drug repurposing offers a promising pathway for therapeutic innovation but requires careful consideration of its complexities and ethical implications to maximize benefits and minimize risks.

Long-term aspirin adherence following myocardial infarction and risk of cardiovascular events

AIMS

Aspirin is considered mandatory after myocardial infarction (MI). However, its long-term efficacy has been questioned. This study investigated the effectiveness of long-term aspirin after MI.

METHODS AND RESULTS

Patients ≥40 years with MI from 2004 to 2017 who were adherent to aspirin 1 year after MI were included from Danish nationwide registries. At 2, 4, 6, and 8 years after MI, continued adherence to aspirin was evaluated. Absolute and relative risks of MI, stroke, or death at 2 years from each time point were calculated using multivariable logistic regression analysis with average treatment effect modelling standardized for age, sex, and comorbidities. Subgroup analyses were stratified by sex and age > and ≤65 years. Among 40 116 individuals included, the risk of the composite endpoint was significantly higher for non-adherent patients at all time points. The absolute risk was highest at 2-4 years after MI for both adherent [8.34%, 95% confidence interval (CI): 8.05-8.64%] and non-adherent patients (10.72%, 95% CI: 9.78-11.66%). The relative risk associated with non-adherence decreased from 4 years after index-MI and onwards: 1.41 (95% CI: 1.27-1.55) at 4-6 years and 1.21 (95% CI: 1.06-1.36) at 8-10 years (Ptrend = 0.056). Aspirin non-adherence in women and individuals >65 years was not associated with increased risk. Pinteraction at each of the time points: Age - <0.001, <0.001, 0.002, 0.51; Sex - 0.25, 0.02, 0.02, 0.82.

CONCLUSION

Non-adherence to long-term aspirin was associated with increased risk of MI, stroke, or death, but not in women or individuals >65 years. The risk decreased from 4 years after MI with near statistical significance.

Stability of the thromboxane B2 biomarker of low-dose aspirin pharmacodynamics in human whole blood and in long-term stored serum samples

Background

Serum thromboxane B2 (sTXB2) is a validated biomarker of low-dose aspirin pharmacodynamics. In the original method, nonanticoagulated blood samples must be incubated at 37 °C immediately after withdrawal, centrifuged and serum supernatant should be frozen until assayed. Timely completion of all preanalytical steps may affect the feasibility and quality of sTXB2 measurements. The storage duration of frozen serum can also affect sTXB2 stability.

Objectives

We assessed the stability of sTXB2 in clotted blood samples stored at 4 °C before further processing and in sera stored at -40 °C for over a decade.

Methods

Venous whole blood withdrawn from individuals on chronic low-dose aspirin was dispensed in different tubes and immediately incubated at 37 °C for 1 hour. The reference tube was promptly processed following the original protocol; the remaining tubes were stored at 4 °C for 12 to 72 hours before further processing. Sera stored at a controlled -40 °C temperature for <1 to 15 years were reassayed. Values within the interassay variation limits (±9%) vs baseline were considered acceptable.

Results

Baseline sTXB2 values (median, 5.4 ng/mL; IQR, 2.4-13.4 ng/mL; n = 40) were comparable with those in samples at 4 °C up to 48 hours (median, 97% [IQR, 86%-104%] of the reference; n = 26), but at 72 hours, the variability exceeded the interassay variation. Thromboxane B2 levels were stable in frozen sera for up to 10 years (median, 101% [IQR, 87%-108%] of the reference; n = 32) but decreased significantly afterward (median, 87% [IQR, 74%-109%] at 15 years; P = .005; n = 32).

Conclusion

Thromboxane B2 is stable in clotted blood samples stored at 4 °C for up to 48 hours before further processing and in serum samples stored at -40 °C over 10 years.

Low-dose aspirin for the prevention of atherosclerotic cardiovascular disease

During the past 30 years, several developments have occurred in the antiplatelet field, including the role of aspirin in primary prevention of atherosclerotic cardiovascular disease. There have been several attempts to develop antiplatelet drugs more effective and safer than aspirin and a shift in emphasis from efficacy to safety, advocating aspirin-free antiplatelet regimens after percutaneous coronary intervention. Evidence supporting a chemopreventive effect of low-dose aspirin against colorectal (and other digestive tract) cancer has also strengthened. The aim of this article is to revisit the role of aspirin in the prevention of atherothrombosis across the cardiovascular risk continuum, in view of developments in the antiplatelet field. The review will offer a clinical perspective on aspirin's mechanism of action, pharmacokinetics, and pharmacodynamics. This will be followed by a detailed discussion of its clinical efficacy and safety.

Needs-based considerations for the role of low-dose aspirin along the CV risk continuum

Cardiovascular disease (CVD) remains the leading cause of death worldwide. The risk of a cardiovascular (CV) event is not static and increases along a continuum, making identification and management complex. Aspirin has been the cornerstone of antiplatelet therapy in CV risk reduction and remains the only antiplatelet agent with current guideline recommendations throughout the CV risk continuum. In light of recent trials, the role of aspirin in CVD prevention in asymptomatic patients has been downgraded in clinical guidelines. However, a substantial proportion of asymptomatic patients have underlying conditions, such as advanced subclinical atherosclerosis that are associated with high CV risk. Advanced subclinical atherosclerosis has not been extensively investigated in patients in clinical trials but in the absence of significant bleeding risks, patients with subclinical atherosclerosis may particularly benefit from preventive aspirin therapy. Recent studies and clinical guidelines support the need for a personalized treatment approach for these patients, balancing their risk of future CV events against their relative bleeding risk. In this commentary, we first discussed various tools and strategies currently available for assessing CV and bleeding risks; we then provided two hypothetical cases to outline how these tools can be implemented for optimal management of patients with no prior CV events who, nonetheless, are susceptible to CVD. The first case details a young and apparently healthy patient with underlying advanced subclinical atherosclerosis; whereas the second case describes a patient with recently diagnosed type 2 diabetes mellitus who is at higher risk of CVD than their non-diabetic counterparts. For both cases, we considered patient clinical characteristics, CV and bleeding risks, as well as other risk factors to evaluate the appropriate treatment strategy and determine whether patients would obtain a net clinical benefit from low-dose aspirin therapy. These cases can serve as examples to guide clinical decision-making on the use of low-dose aspirin for primary CVD prevention and improve CVD management via a personalized approach.

Assessment of ADRB1 polymorphism in patients with acute coronary syndrome treated with ticagrelor and aspirin

Background: This study investigated the influence of ADRB1 gene rs1801253 polymorphism on the treatment response of ticagrelor and aspirin in patients with acute coronary syndrome (ACS). Methods: Genetic typing was detected by Sanger sequencing. Platelet inhibition was assessed using thromboelastography. Kaplan-Meier and Cox regression were applied for prognosis analysis. Results: Out of 200 participants, 94 cases with rs1801253-CC genotype and 106 cases with CG+GG genotype were found. There was no significant difference between the rs1801253-CC and CG+GG groups in the number of ST-segment elevation myocardial infarction, non-ST-segment elevation myocardial infarction and unstable angina patients. There was no statistical difference in the basic data of patients in the two groups in terms of age, sex, medical history and medicine use in the dominant model. The rs1801253-CC genotype was a risk prognostic factor for ACS patients based on the Cox regression analysis results. Conclusion: Detecting ADRB1 polymorphism is crucial for ACS patients undergoing treatment with ticagrelor and aspirin.

Drug Repurposing for Effective Alzheimer's Disease Medicines: Existing Methods and Novel Pharmacoepidemiological Approaches

Drug repurposing is a methodology used to identify new clinical indications for existing drugs developed for other indications and has been successfully applied in the treatment of numerous conditions. Alzheimer's disease (AD) may be particularly well-suited to the application of drug repurposing methods given the absence of effective therapies and abundance of multi-omic data that has been generated in AD patients recently that may facilitate discovery of candidate AD drugs. A recent focus of drug repurposing has been in the application of pharmacoepidemiologic approaches to drug evaluation. Here, real-world clinical datasets with large numbers of patients are leveraged to establish observational efficacy of candidate drugs for further evaluation in disease models and clinical trials. In this review, we provide a selected overview of methods for drug repurposing, including signature matching, network analysis, molecular docking, phenotypic screening, semantic network, and pharmacoepidemiological analyses. Numerous methods have also been applied specifically to AD with the aim of nominating novel drug candidates for evaluation. These approaches, however, are prone to numerous limitations and potential biases that we have sought to address in the Drug Repurposing for Effective Alzheimer's Medicines (DREAM) study, a multi-step framework for selection and validation of potential drug candidates that has demonstrated the promise of STAT3 inhibitors and re-evaluated evidence for other drug candidates, such as phosphodiesterase inhibitors. Taken together, drug repurposing holds significant promise for development of novel AD therapeutics, particularly as the pace of data generation and development of analytical methods continue to accelerate.

Review of Under-Recognized Adjunctive Therapies for Cancer

Patients and providers may not be aware that several adjunctive measures can significantly improve the quality of life, response to treatment, and possibly outcomes for cancer patients. This manuscript presents a review of practical under-recognized adjunctive therapies that are effective including exercise; stress-reduction techniques such as mindfulness, massage, yoga, Tai Chi, breathing exercises; importance of sleep quality; diet modifications such as calorie restriction at the time of chemotherapy and avoidance of high carbohydrate foods; supplements such as aspirin, green tea, turmeric, and melatonin; and repurposed prescription medications such as metformin and statins. Each recommendation should be tailored to the individual patient to assure no contraindications.

Physiologically based modelling of the antiplatelet effect of aspirin: A tool to characterize drug responsiveness and inform precision dosing

A computational approach involving mathematical modeling and in silico experiments was used to characterize the determinants of extent and duration of platelet cyclooxygenase (COX)-1 inhibition by aspirin and design precision dosing in patients with accelerated platelet turnover or reduced drug bioavailability. To this purpose, a recently developed physiologically-based pharmacokinetics (PK) and pharmacodynamics (PD) model of low-dose aspirin in regenerating platelets and megakaryocytes, was used to predict the main features and determinants of platelet COX-1 inhibition. The response to different aspirin regimens in healthy subjects and in pathological conditions associated with alterations in aspirin PK (i.e., severely obese subjects) or PD (i.e., essential thrombocytemya patients), were simulated. A model sensitivity analysis was performed to identify the main processes influencing COX-1 dynamics. In silico experiments and sensitivity analyses indicated a major role for megakaryocytes and platelet turnover in determining the extent and duration of COX-1 inhibition by once-daily, low-dose aspirin. They also showed the superiority of reducing the dosing interval vs increasing the once-daily dose in conditions of increased platelet turnover, while suggested specific dose adjustments in conditions of possible reduction in drug bioavailability. In conclusion, the consistency of our model-based findings with experimental data from studies in healthy subjects and patients with essential thrombocythemia supports the potential of our approach for describing the determinants of platelet inhibition by aspirin and informing precision dosing which may guide personalized antithrombotic therapy in different patient populations, especially in those under-represented in clinical trials or in those associated with poor feasibility.