Faculty Bibliography

Indeterminate pulmonary nodules (IPNs), which are nodules that cannot be classified as definitively benign or malignant at the time of detection, are now diagnosed on the order of millions per year. Management of IPNs remains heavily debated, and routine practice ultimately involves some balance of overall clinical risk assessment and additional diagnostic tests or procedures which may generate significant risk, cost, and worry. Biomarkers are biologically based tests or indicators capable of accurately characterizing the physiologic properties of homeostasis and disease that are not otherwise easily evaluated by the clinician. Accurate biomarkers thereby serve as reliable surrogates for biological aberrancy, and importantly for the field of diagnostics, can signal early pathology before it becomes clinically detectable. In the realm of IPNs, biomarker development seeks to address a growing need for noninvasive adjunct tools that can be leveraged clinically to add clarity where diagnostic uncertainty exists. Here, effective diagnostic biomarkers have the potential to hone clinical management, accelerate treatment when indicated, and curb added unnecessary diagnostics. In this review article, the authors highlight the role for biomarkers in the diagnosis of IPNs, outline the methodology for successful biomarker development, and discuss contemporary IPN biomarker research and the remaining challenges and future directions for the field.

INTRODUCTION/UNASSIGNED:Outcomes for NSCLC remain suboptimal. Recent data suggest that cryoablation can generate antitumor immune effects. In this first-in-human phase I clinical trial, we investigated the safety and feasibility of bronchoscopic cryoimmunotherapy (BCI) delivered during standard-of-care bronchoscopy and explored associated systemic immune responses. METHODS/UNASSIGNED:Subjects with known or suspected advanced-stage NSCLC were recruited. BCI was delivered in dose-escalated freeze-thaw cycles to determine maximum dose tolerance. Feasibility assessment was determined with a pre-set goal of achieving successful BCI in more than or equal to 80% of subjects. Safety was assessed by review of BCI-related complications, including grades 2 to 3 bleeding, pneumothorax requiring intervention, and National Cancer Institute Common Terminology Criteria for Adverse Events grade 3 to 5 adverse events. Pre- and post-BCI blood samples were collected to explore changes in the systemic immune profile. RESULTS/UNASSIGNED:Subjects with predominantly clinical TNM stage 3 or 4 adenocarcinoma or squamous cell carcinoma were enrolled. We reached the maximum dose of 30 seconds with 100% feasibility and no BCI-related adverse events. In peripheral blood analysis, we observed a significant decrease in derived neutrophil-to-lymphocyte ratio in the high-dose BCI group in comparison to the low-dose BCI cohort. We also observed increases in inflammatory cytokines-GM-CSF, IFN-γ, IL-1β, IL-17A, and IL-2-and effector memory T cells post-BCI. CONCLUSION/UNASSIGNED:BCI is safe and feasible. In addition, we provide preliminary evidence that at higher dose levels there is a systemic immune response consistent with a cytotoxic profile. Further immune analyses will determine the potential of BCI as an adjunctive therapy in combination with immune checkpoint inhibition in NSCLC treatment.

Variations in the airway microbiome are associated with inflammatory responses in the lung and pulmonary disease outcomes. Regional changes in microbiome composition could have spatial effects on the metabolic environment, contributing to differences in the host response. Here, we profiled the respiratory microbiome (metagenome/metatranscriptome) and metabolome of a patient cohort, uncovering topographical differences in microbial function, which were further delineated using isotope probing in mice. In humans, the functional activity of taxa varied across the respiratory tract and correlated with immunomodulatory metabolites such as glutamic acid/glutamate and methionine. Common oral commensals, such as Prevotella, Streptococcus, and Veillonella, were more functionally active in the lower airways. Inoculating mice with these commensals led to regional increases in several metabolites, notably methionine and tyrosine. Isotope labeling validated the contribution of Prevotella melaninogenica in generating specific metabolites. This functional characterization of microbial communities reveals topographical changes in the lung metabolome and potential impacts on host responses.

INTRODUCTION/UNASSIGNED:Up to 11% of patients are left with residual lung abnormalities following COVID-19 infection. It is unclear whether these changes resolve over time or progress to fibrosis. The airway microbiome is altered in interstitial lung disease, potentially contributing to pathogenesis and disease progression. We hypothesised that the airway microbiome in patients with post-COVID-19 residual lung abnormalities may be altered. METHODS/UNASSIGNED:The POST COVID-19 interstitial lung DiseasE (POSTCODE) study recruited subjects with post-COVID-19 residual lung abnormalities for bronchoscopy. 16S ribosomal RNA gene amplicon sequencing was performed on DNA extracted from bronchoalveolar lavage fluid and compared with that from patients with idiopathic pulmonary fibrosis, fibrotic hypersensitivity pneumonitis and control subjects. RESULTS/UNASSIGNED:and higher α-diversity in subjects with post-COVID-19 residual lung abnormalities. CONCLUSIONS/UNASSIGNED:The microbiome and bacterial burden in the lower airways of subjects with post-COVID-19 residual lung abnormalities do not differ from those of controls. The microbiome differs from idiopathic pulmonary fibrosis. This, and the absence of associations between microbial features and disease severity or clinical outcomes, suggests that the microbiome is unlikely to contribute to residual lung abnormalities in patients recovering from COVID-19 infection.

Non-small cell lung cancer (NSCLC) remains the most common cause for cancer-related mortality despite advances in treatment. Early detection is crucial for improving patient outcomes, yet current diagnostic and prognostic molecular biomarkers lack the sensitivity and specificity necessary to become clinically useful. Recent studies revealed that the lower airway microbiome play a role in NSCLC and that microbial signatures are associated with NSCLC development, progression, and prognosis, suggesting the potential for microbiome-based biomarkers for early diagnosis and risk stratification. Here we review recent advances in the role of the local and systemic microbiome in early-stage NSCLC. Primarily, several studies have identified specific microbial taxa associated with lung cancer suggesting novel insights into disease pathogenesis and progression. Integration of microbiome data with other 'omics' platforms, such as host transcriptomics and metabolomics, has the potential to enhance our understanding of microbial-host interactions and may provide more comprehensive biomarker signatures. While promising, challenges remain to the development of microbiome-based biomarkers such as those related to differences in samples utilized, sequencing methods, and data analysis. Here, we discuss such challenges as well as future directions for research needed to fulfil the promise of microbiome-based biomarkers for changing early detection and management strategies in NSCLC.