LPS from bovine serum albumin drives TNF-α release during ex-vivo placenta perfusion experiments, contaminates the perfusion system but can be effectively removed by oxidative cleaning

INTRODUCTION

The dual ex-vivo perfusion of human placental tissue is useful to study inflammatory pathways. We found significant TNF-α release in negative controls similar in concentration to lipopolysaccharide (LPS) stimulated placentas. The aim of the current study was to (i) identify sources driving TNF-α release and (ii) develop an approach to control for it.

METHOD

(i) To determine sources leading to TNF-α release, solutions frequently circulated through the perfusion system and perfusion media with different bovine serum albumin (BSA) quality were exposed to mouse macrophage cell lines (RAW264.7) and subsequently measured for TNF-α expression. (ii) To assess memory effects and validate cleaning procedures, sham perfusion experiments were conducted either in the presence or absence of exogenous LPS, in new tubing that was contaminated, cleaned and analyzed for the effectiveness of LPS removal. Oxidative and acid-base cleaning were tested for their effectiveness to reduce LPS contamination.

RESULTS

TNF-α release, observed in negative control experiments, was attributed to the use of LPS-contaminated BSA as well as inadequate cleaning of the perfusion system. Once introduced in the perfusion system, LPS accumulated and created a memory effect. Oxidative but not acid-base depyrogenation effectively reduced LPS levels to concentrations that were in accordance with FDA guidelines (<0.5 EU/mL) for medical equipment redeemed appropriate for re-use.

DISCUSSION

LPS contamination of the placenta perfusion model could have confounding effects on experimental outcomes leading to misinterpretation of data. To circumvent LPS contamination LPS-free BSA and oxidative depyrogenation cleaning techniques should be implemented in future placental perfusion studies.

Analysis of risk factors for immune-related adverse events induced by immune checkpoint inhibitor treatment in cancer: A comprehensive systematic review

BACKGROUND

Immune-related adverse events (irAE) pose challenges to the use of immune checkpoint inhibitors (ICI). While risk factors for irAE are emerging, most studies are small, retrospective analyses that seldom report on diverse cancers or rare irAE. This paper reports a systematic review that summarises literature on irAE risk factors across cancers and proposes a categorisation approach.

METHOD

A systematic search was conducted in Medline OVID, Embase and Web of Science databases following PRISMA guidelines (CRD42022310127). Original research published in peer-reviewed journals between January 2017-Decmeber 2021 were selected. Eligible studies included patients with any cancer and evaluated any potential risk factor for any grade/type of irAE. Study design, sample size, and method for analysing association between irAE and risk factors were compared.

RESULTS

A total of 293 eligible studies containing 305,879 patients receiving ICI reported irAE in 58,291 patients (19.1 %). There were 221 retrospective, 55 prospective studies, and 17 systematic reviews/meta-analyses. Eighteen studies evaluated the predictive validity of models. Proposed risk factors were grouped based on common themes and underlying aetiology: 1) patient, 2) laboratory, 3) medical history, 4) cancer-related, 5) clinical score, 6) medications, and 7) imaging features. Opposing associations were reported between advancing age and irAE risk.

CONCLUSION

This systematic review provides a comprehensive overview of evidence on irAE risk factors across a large patient population. Studies were heterogeneous resulting from variations in design, sample size and analysis method, and lack generalisability due to statistically underpowered evidence. We propose an approach to categorise potential irAE risk factors to support ongoing collaborative research.

Cancer and treatment specific incidence rates of immune-related adverse events induced by immune checkpoint inhibitors: a systematic review

BACKGROUND

Immune-related adverse events (irAE) induced by immune checkpoint inhibitors (ICI) are a treatment-limiting barrier. There are few large-scale studies that estimate irAE prevalence. This paper presents a systematic review that reports the prevalence of irAE by cancer type and ICI.

METHODS

A systematic review was undertaken in MEDLINE OVID, EMBASE and Web of Science databases from 2017-2021. A total of 293 studies were identified for analysis and, of these, event rate was calculated for 272 studies, which involved 58,291 patients with irAE among 305,879 total patients on ICI. Event rate was calculated by irAE and ICI type.

RESULTS

Mean event rate for general irAE occurrence across any grade was 40.0% (37.3-42.7%) and high grade was 19.7% (15.8-23.7%). Mean event rates for six specific types of irAE are reported. Mean event rate for ICI monotherapy was 30.5% (28.1-32.9%), 45.7% (29.6-61.7%) for ICI combination therapy, and 30.0% (25.3-34.6%) for both ICI monotherapy and combination therapy.

CONCLUSION

This systematic review characterises irAE prevalence across current research that examines irAE risk factors across cancers and ICI. The findings confirms that irAE occurrence is very common in the real-world setting, both high grade and irAE across any grade.