Interstitial lung disease and associated fibrosis occur in a proportion of individuals who have recovered from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection through unknown mechanisms. We studied individuals with severe coronavirus disease 2019 (COVID-19) after recovery from acute illness. Individuals with evidence of interstitial lung changes at 3 to 6 months after recovery had an up-regulated neutrophil-associated immune signature including increased chemokines, proteases, and markers of neutrophil extracellular traps that were detectable in the blood. Similar pathways were enriched in the upper airway with a concomitant increase in antiviral type I interferon signaling. Interaction analysis of the peripheral phosphoproteome identified enriched kinases critical for neutrophil inflammatory pathways. Evaluation of these individuals at 12 months after recovery indicated that a subset of the individuals had not yet achieved full normalization of radiological and functional changes. These data provide insight into mechanisms driving development of pulmonary sequelae during and after COVID-19 and provide a rational basis for development of targeted approaches to prevent long-term complications.

Background: Neutrophil extracellular traps’ (NETs’) formation is a mechanism of defense that neutrophils deploy as an alternative to phagocytosis, to constrain the spread of microorganisms. Aim: The aim was to evaluate biomarkers of NETs’ formation in a patient cohort admitted to intensive care unit (ICU) due to infection. Methods: Forty-six septic shock patients, 22 critical COVID-19 patients and 48 matched control subjects were recruited. Intact nucleosomes containing histone 3.1 (Nu.H3.1), or citrullinated histone H3R8 (Nu.Cit-H3R8), free citrullinated histone (Cit-H3), neutrophil elastase (NE) and myeloperoxidase (MPO) were measured. Results: Significant differences in Nu.H3.1 and NE levels were observed between septic shock and critical COVID-19 subjects as well as with controls (p-values < 0.05). The normalization of nucleosome levels according to the neutrophil count improved the discrimination between septic shock and critical COVID-19 patients. The ratio of Nu.Cit-H3R8 to Nu.H3.1 allowed the determination of nucleosome citrullination degree, presumably by PAD4. Conclusion: H3.1 and Cit-H3R8 nucleosomes appear to be interesting markers of global cell death and neutrophil activation when combined. Nu.H3.1 permits the evaluation of disease severity and differs between septic shock and critical COVID-19 patients, reflecting two distinct potential pathological processes in these conditions.

The molecular profiling of circulating tumor DNA (ctDNA) is a helpful tool not only in cancer treatment, but also in the early detection of relapse. However, the clinical interpretation of a ctDNA negative result remains challenging. The characterization of circulating nucleosomes (carrying cell-free DNA) and associated epigenetic modifications (playing a key role in the tumorigenesis of different cancers) may provide useful information for patient management, by supporting the contributive value of ctDNA molecular profiling. Significantly elevated concentrations of H3K27Me3 nucleosomes were found in plasmas at the diagnosis, and during the follow-up, of NSCLC patients, compared to healthy donors (p-value < 0.0001). By combining the H3K27Me3 level and the ctDNA molecular profile, we found that 25.5% of the patients had H3K27Me3 levels above the cut off, and no somatic alteration was detected at diagnosis. This strongly supports the presence of non-mutated ctDNA in the corresponding plasma. During the patient follow-up, a high H3K27Me3-nucleosome level was found in 15.1% of the sample, despite no somatic mutations being detected, allowing the identification of disease progression from 43.1% to 58.2% over molecular profiling alone. Measuring H3K27Me3-nucleosome levels in combination with ctDNA molecular profiling may improve confidence in the negative molecular result for cfDNA in lung cancer at diagnosis, and may also be a promising biomarker for molecular residual disease (MRD) monitoring, during and/or after treatment.

Background: Molecular profiling of circulating tumor DNA (ctDNA) is a helpful tool for cancer treatment indication or for the early detection of relapse. In patients with advanced lung adenocarcinoma cancers (NSCLC), a subset can be cured by immunotherapy, radiotherapy, and/or chemotherapy combined regimens, or targeted therapies depending on their ctDNA molecular profile. But clinical interpretation of ctDNA negative result remains often challenging. Taking advantage that cell-free DNA in association with nucleosomes are released into the bloodstream upon cell death, the characterization of both may give a benefit to patient management. Indeed, dysregulations of epigenetic modifications, such as histone methylation, are found to play a key role in tumorigenesis of different cancers. However, the concentration of circulating nucleosomes in blood, as a biomarker of the contributive value of ctDNA molecular profiling in patient management at diagnosis or during patient follow-up have not previously been investigated. Results: Significantly elevated concentrations of H3K27Me3-nucleosomes were found in NSCLC plasmas at diagnosis and during the follow-up of patients compared to healthy donors (median: 24ng/mL; 16.9ng/mL vs 8ng/mL, p-value < 0.0001, respectively). Interestingly, by combining H3K27Me3 level and ctDNA molecular profile, we found that 25.5% of the patients had high levels of H3K27Me3 (above 22.5 ng/mL) and no somatic alteration detected at diagnosis. This strongly supports the presence of non-mutated ctDNA in the corresponding plasma. During patient follow-up, H3K27Me3 level was lower in ctDNA-negative group compared to ctDNA-positive group (medianctDNA- = 13.4 ng/mL vs medianctDNA+ = 26.1 ng/mL, respectively, p-value < 0.0001). In 41.8% of the samples, no somatic mutation and low level of H3K27Me3-nucleosomes were observed suggesting molecular indicator of treatment response. In contrast, high H3K27Me3-nucleosome levels were found in 15.1% of the samples despite no somatic mutations being detected allowing the identification of disease progression from 43.1% to 58.2% over molecular profiling only. Conclusion: H3K27Me3-nucleosome level is proposed to be a useful biomarker of the contributive value of ctDNA molecular profiling at diagnosis by greatly improving the confidence in the negative molecular result in cfDNA in lung cancer. In addition, H3K27Me3-nucleosome could be a promising biomarker for Molecular Residual Disease monitoring in NSCLC during or after treatment.

Introduction: Treatment options of lung cancer (LC) comprise radiotherapy, and/or combined treatment approaches, including chemotherapy, immunotherapy and targeted therapies based on the tumoral molecular profile. Following curative-intent first-line therapies, clinical surveillance involves serial CT imaging. However, such surveillance can detect only macroscopic disease recurrence and is frequently inconclusive. NGS has been utilized to help identify and monitor treatment plans. Nucleosomes, complexes of DNA and histones proteins, are released during cell death into blood circulation. Trimethylation of lysine 27 on histone H3 (H3K27Me3), catalyzed by enhancer of zeste homolog 2 (EZH2), is a crucial epigenetic process in tumorigenesis. We investigated if H3K27Me3-nucleosome concentration could be a biomarker for molecular residual disease (MRD). Patients and Methods: Plasmas were retrospectively collected from patients with advanced LC during treatment (CIRCAN’s cohort, n= 200) and from healthy donors (n=100). We carried out standard targeted NGS on paired plasmas. Samples were divided in two sub-groups based on genetical results: ctDNA negative (n=120) or positive (n=80) for presence of somatic alterations. Concentration of circulating H3K27Me3-nucleosome was measured using chemiluminescent Nu.Q® immunoassay (Belgian Volition SRL, Belgium). Results: Significantly elevated concentrations of H3K27Me3-nucleosomes were found in LC plasmas during the follow-up of patients compared to healthy donors (median 14.9 ng/ml vs 6.15 ng/ml, respectively, p&lt;0.001). In addition, H3K27Me3 levels is lower in the ctDNA-negative group compared to ctDNA-positive group (median 12.1 vs 24.8 ng/ml, respectively, p&lt;0.001). At a clinical cut-off of 14 ng/ml, 62% of samples were positive for either H3K27Me3 or ctDNA, or for both, suggesting an active disease progression compared to only 40% detection using the NGS assay alone. 38% of the patients have low levels of H3K27Me3 and were ctDNA-negative strongly suggesting a therapeutic response under treatment. Conclusions: High levels of Nu.Q® H3K27Me3 could allow physicians to detect MRD in LC patients following treatment with curative intent. This could be achieved by monitoring testing of patients at defined intervals of treatment and recovery, alongside imaging, to incorporate analyses of evolving molecular landscapes during treatment. In this setting, the H3K27Me3-nucleosome quantification, to complete the molecular exploration of cfDNA is highly encouraging, especially in advanced NSCLC, where re-tissue biopsies are impractical, expensive, and may cause undue harm. H3K27Me3-nucleosome quantification may also be useful in patient identification for specific treatments such as EZH2 inhibitor, but this requires investigation. Citation Format: Emmanuel Grolleau, Julie Candiracci, Arnaud Gauthier, Gaelle Lescuyer, David Barthelemy, Christine Haon, Florence Geiguer, Margaux Raffin, Nathalie Hardat, Julie Balandier, Rémi Rabeuf, Anne-Sophie Wozny, Guillaume Rommelaere, Claire Rodriguez-Lafrasse, Fabien Subtil, Sébastien Couraud, Marielle Herzog, Lea Payen-Gay. Circulating H3K27 nucleosomes to monitor lung cancer patients during treatment, a universal biomarker quantifying the molecular residual disease (MRD) in plasma samples [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2163.