Novel biomarkers for drug-induced liver injury

Introduction: Liver toxicity due to medicines (drug-induced liver injury) is a challenge for clinicians and drug developers. There are well-established biomarkers of drug-induced liver injury, which are widely used and validated by decades of clinical experience. These include alanine aminotransferase and bilirubin. Limitations of the current biomarkers are well described, and this has resulted in global efforts to identify and develop new candidates. This process has been aided by regulatory pathways being established for biomarker qualification. This article aims to provide a broad overview of the mechanisms of liver toxicity and discuss emerging novel biomarkers. There is a focus on the recent advances in the identification and validation of novel biomarkers, their potential applications in drug development and clinical practice, and the challenges and opportunities in translating these biomarkers into routine clinical use.Current gold-standard biomarkers: Alanine and aspartate aminotransferase activities perform well in diagnosing established drug-induced liver injury but may lack specificity and are not prognostic. The burden of proof for novel biomarkers: The amount of evidence required for a new biomarker will depend on its context-of-use, specifically on the impact on patient outcome of a false negative or false positive result. Leading potential biomarkers: Cytokeratin-18, glutamate dehydrogenase, microRNA-122, high-mobility group box 1 proteins, osteopontin, and colony-stimulating factor receptor are examples of lead candidates. Potential applications of novel biomarkers: The early detection of drug-induced liver injury, interpretation of an alanine aminotransferase activity increase, and decisions about dose escalation in clinical trials may all be informed by new biomarkers. Conclusions: There have been numerous exploratory studies describing differences in biomarkers and their potential value in risk-stratifying populations or identifying specific patients who may be failed by current assessment protocols. Additionally, the use of exploratory biomarkers to guide clinical trial decision-making is becoming routine. The challenge is now clinically validating leading candidate biomarkers in the assessment of patients presenting with conditions such as paracetamol overdose, which place them at risk of acute liver injury. This will require robust clinical trials. If the use of these biomarkers is to be widely adopted, they will need to unequivocally demonstrate benefit in overall cost, morbidity or mortality. <br/

Towards quantitative point of care detection using SERS lateral flow immunoassays

The rapid detection of biomolecules in a point of care (POC) setting is very important for diagnostic purposes. A platform which can provide this, whilst still being low cost and simple to use, is paper based lateral flow immunoassays (LFIA). LFIA combine immunology and chromatography to detect a target by forming an immunocomplex with a label which traps them in a test zone. Qualitative analysis can be performed using the naked eye while quantitative analysis takes place by measuring the optical signal provided by the label at the test zone. There are numerous detection methods available, however many suffer from low sensitivity, lack of multiplexing capabilities or are poor at providing POC quantitative analysis. An attractive method to overcome this is to use nanoparticles coated in Raman reporters as the labelled species and to analyse test zones using surface enhanced Raman scattering (SERS). Due to the wide variety of metal nanoparticles, Raman reporter and laser excitations that are available, SERS based LFIA have been adapted to identify and quantify multiple targets at once. Large Raman microscopes combined with long mapping times have limited the platform to the lab, however by transferring the analysis to portable Raman instruments, rapid and quantitative measurements can be taken at the POC without any loss in sensitivity. Portable or handheld SERS-LFIA platforms can therefore be used anywhere, from modern clinics to remote and resource-poor settings. This review will present an overview of SERS-based LFIA platforms and the major recent advancements in multiplexing and portable and handheld detection with an outlook on the future of the platform

A Metabolomic Analysis Of Thiol Response For Standard And Modified N-Acetyl Cysteine Treatment Regimens In Patients With Acetaminophen Overdose

Abstract N‐acetylcysteine (NAC) is an antidote to prevent acetaminophen (paracetamol‐APAP)‐induced acute liver injury (ALI). The 3‐bag licensed 20.25 h standard regimen, and a 12 h modified regimen, are used to treat APAP overdose. This study evaluated the redox thiol response and APAP metabolites, in patients with a single APAP overdose treated with either the 20.25 h standard or 12 h modified regimen. We used liquid chromatography tandem mass spectrometry to quantify clinically important oxidative stress biomarkers and APAP metabolites in plasma samples from 45 patients who participated in a randomized controlled trial (SNAP trial). We investigated the time course response of plasma metabolites at predose, 12 h, and 20.25 h post‐start of NAC infusion. The results showed that the 12 h modified regimen resulted in a significant elevation of plasma NAC and cysteine concentrations at 12 h post‐infusion. We found no significant alteration in the metabolism of APAP, mitochondrial, amino acids, and other thiol biomarkers with the two regimens. We examined APAP and purine metabolism in overdose patients who developed ALI. We showed the major APAP‐metabolites and xanthine were significantly higher in patients with ALI. These biomarkers correlated well with alanine aminotransferase activity at admission. Receiver operating characteristic analysis showed that at admission, plasma APAP‐metabolites and xanthine concentrations were predictive for ALI. In conclusion, a significantly higher redox thiol response with the modified NAC regimen at 12 h postdose suggests this regimen may produce greater antioxidant efficacy. At baseline, plasma APAP and purine metabolites may be useful biomarkers for early prediction of APAP‐induced ALI