Circulating Levels of Endotrophin Are Prognostic for Long-Term Mortality after AKI

Endotrophin as a Biomarker for Severe Acute Kidney Injury and Major Adverse Kidney Events

Key Points

Background

The search for novel biomarkers in AKI continues, both for being able to predict adverse events in AKI but also for confirming pathogenic pathways as potential therapeutic targets. Endotrophin (ETP) is an emerging biomarker in a number of fibroinflammatory diseases. We sought to test the association of ETP with the development of a major adverse kidney event (MAKE) in critically ill adult patients.

Methods

Single-center prospective study of critically ill adult patients with stage 2–3 AKI and patients without AKI. Serum ETP was measured early in the first 3 days of critical care admission, 5–7 days later, and in some patients, 4–6 weeks later. The primary outcome was MAKE assessed at hospital discharge, a composite of mortality, RRT at discharge, and eGFR reduction of ≥25% from baseline.

Results

Among 121 patients evaluated in this study, serum ETP was significantly higher in patients with AKI versus those without (P < 0.05). In multivariable logistic regression analysis, higher tertiles of ETP were significantly associated with MAKE at discharge, controlled for relevant covariates. Furthermore, sustained elevations in ETP 5–7 days later, as opposed to reductions toward normal, were also associated with MAKE. In patients seen in the clinic 4–6 weeks post-AKI, ETP remained elevated. In the acute period, ETP levels correlated most with TNF-α and neutrophil gelatinase-associated lipocalin.

Conclusions

Higher levels of serum ETP early in the intensive care unit admission, as well as sustained elevations of ETP within a 5-day to 7-day period, are associated with MAKE at hospital discharge. ETP is a potential biomarker of AKI-related outcomes and a promising therapeutic target to minimize sequelae of AKI.

Biomarker-guided drug development provides value for patients, payers and drug developers: lessons learned from 25 years in the biomarker industry

INTRODUCTION

There is an urgent, persistent, need for better biomarkers in clinical drug development. More informative biomarkers can increase the likelihood of drug advancement or approval, and implementing biomarkers increases the success rate in drug development. Biomarkers may guide decisions and allow resources to be directed to the projects most likely to succeed. However, biomarkers that are validated to high standards are needed, reflecting biological and pathological processes accurately. Such biomarkers are needed to develop treatments faster, and to improve and guide clinical trial design by selecting and de-selecting patients.

METHODS

In this review based on the authors' previous published experience and interaction with pharmaceutical- and biomarker stakeholders, we highlight the use and value of biomarkers in clinical development according to the BEST guidelines. We highlight the value of 3 types of biomarkers that may provide optimal value to stakeholders: diagnostic, prognostic and pharmacodynamic biomarkers.

RESULTS

A more appropriate clinical trial design, increasing the ratio between benefits and side effects, may come from a more tailored biomarker-approach identifying suitable molecular endotypes of patients to treat.

DISCUSSION

Biomarkers may guide drug developers in selecting the optimal projects to progress, when designing clinical studies and development paths. Biomarkers may aid in the diagnosis and prognostic assessment of patients and assist in matching the molecular endotype to the selected treatment, which improves the success rate of clinical development progression. The aim of this paper is to provide a comprehensive ideation framework for how to utilize biomarkers in clinical development, with a focus on utility for patients, payers and drug developers.

Endotrophin, a Key Marker and Driver for Fibroinflammatory Disease

Our overview covers several key areas related to recent results obtained for collagen type VI and endotrophin (ETP). (1) An introduction to the history of ETP, including how it was identified, how it is released, and its function and potential receptors. (2) An introduction to the collagen family, with a focus on what differentiates collagen type VI from an evolutionary standpoint. (3) An overview of collagen type VI, the 6 individual chains (COL6A1, A2, A3, A4, A5, and A6), their differences and similarities, as well as their expression profiles and function. (4) A detailed analysis of COL6A3, including the cleaved product endotrophin, and what separates it from the other 5 collagen 6 molecules, including its suggested function based on insights gained from knockout and gain of function mouse models. (5) The pathology of ETP. What leads to its presence and release and what are the consequences thereof? (6) Functional implications of circulating ETP. Here we review the data with the functional roles of ETP in mind. (7) We propose that ETP is a mediator for fibrotic (or fibroinflammatory) disorders. Based on what we know about ETP, we have to consider it as a target for the treatment of fibrotic (or fibroinflammatory) disorders. What segment(s) of the patient population would most dramatically respond to an ETP-targeted intervention? How can we find the population that would profit most from an intervention? We aim to present a broad overview over the ETP field at large, providing an assessment of where the future research efforts need to be placed to tap into the vast potential of ETP, both as a marker and as a target in different diseases.

A comprehensive description of kidney disease progression after acute kidney injury from a prospective, parallel-group cohort study

Acute kidney injury (AKI) is associated with adverse long-term outcomes, but many studies are retrospective, focused on specific patient groups or lack adequate comparators. The ARID (AKI Risk in Derby) Study was a five-year prospective parallel-group cohort study to examine this. Hospitalized cohorts with and without exposure to AKI were matched 1:1 for age, baseline kidney function, and diabetes. Estimated glomerular filtration rate (eGFR) and the urinary albumin:creatinine ratio (uACR) were measured at three-months, one-, three- and five-years. Outcomes included kidney disease progression, heart failure episodes and mortality. In 866 matched individuals, kidney disease progression at five years was found to be significantly increased in 30% of the exposed group versus 7% of those non-exposed (adjusted odds ratio 2.49 [95% confidence interval 1.43 to 4.36]). In the AKI group, this was largely characterized by incomplete recovery of kidney function by three months. Further episodes of AKI during follow-up were significantly more common in the exposed group (odds ratio 2.71 [1.94 to 3.77]) and had an additive effect on risk of kidney disease progression. Mortality and heart failure episodes were more frequent in the exposed group, but the association with AKI was no longer significant when models were adjusted for three-month eGFR and uACR. In a general hospitalized population, kidney disease progression after five years was common and strongly associated with AKI. Thus, the time course of changes and the attenuation of associations with adverse outcomes after adjustment for three-month eGFR and uACR suggest non-recovery of kidney function is an important assessment in post-AKI care and a potential future target for intervention. STUDY REGISTRATION: ISRCTN25405995.