Infection Impacts dd-cfDNA in Lung Transplant Recipients

Purpose: Infection is the leading cause of death within 1 year post lung transplant. Graft injury secondary to infection is affected by both source and organism. Donor derived cell-free DNA (dd-cfDNA) is a consistent marker of graft injury, but previously reported dd-cfDNA levels with infections have been inconsistent. We compared dd-cfDNA concentrations across different infection types. Method(s): We reviewed infections in lung transplant recipients (LTR) between 5/2019-6/2021 with paired dd-cfDNA at time of infection. All were confirmed infections (i.e. requiring therapy). Infection source (respiratory vs non-respiratory) and organism were collected. Samples were excluded if there was concurrent ACR, AMR or CLAD at time of dd-cfDNA. The primary endpoint was dd-cfDNA levels across cohorts. Result(s): Fifty paired samples from 20 LTR were identified;31 samples were excluded due to concurrent diagnoses. Infections included viral (n=18, 36%), bacterial (n=18, 36%), and fungal (n=10, 20%). Four cultures (8%) had multiple organisms. Most common within each group were CMV (n=4) and COVID (n=4) for viral, Pseudomonas aeruginosa (n=4) for bacterial, and Aspergillus (n=7) for fungal. Median dd-cfDNA was 1.30% in viral infections, 1.93% in bacterial, and 0.99% in fungal;respiratory infections (n=42) was 1.42% and 0.95% in non-respiratory (n=8). Conclusion(s): There was a statistically significant increase in dd-cfDNA between each infection compared to a normal cohort, but no statistical differences between infection groups. The trend towards significance of respiratory vs non-respiratory indicates that dd-cfDNA may be a useful marker of injury specific to the graft caused by infection. Further investigation with serial samples prior to and following treatment of the infection will be important to better understand this trend. (Figure Presented).

An update on the STRATIFY (staging by thoracoscopy in potentially radically treatable non-small cell lung cancer associated with minimal pleural effusion) study

IntroductionPleural effusion is common in lung cancer. Metastatic disease may be confirmed on imaging or fluid sampling. A minority of patients however with otherwise radically treatable disease have a small effusion not amenable to aspiration, or from which fluid cytology is negative;termed minimal pleural effusion (mini-PE). Previous retrospective studies associate significantly shorter survival in mini-PE than stage-matched cases without mini-PE and hypothesise this reflects occult pleural metastases (OPM) in up to 80% of patients. STRATIFY (Staging by Thoracoscopy in Potentially Radically Treatable Non-Small Cell Lung Cancer (NSCLC) Associated with Minimal Pleural Effusion) is a multicentre, prospective observational study, which will determine the true prevalence of OPM in this setting. An update on the study is provided here.MethodsSTRATIFY was funded by Chief Scientist Office and opened to recruitment in Jan-20. Target n=96 across 8 UK centres in 18 months. Key eligibility criteria include Mini-PE (defined by an ipsilateral effusion <1/3 hemithorax on chest radiograph), radically treatable NSCLC and LAT feasibility (defined by sufficient fluid ± lung sliding on screening ultrasound). Primary endpoint: Prevalence of OPM, defined as NSCLC cells in parietal pleural biopsies. Key secondary endpoints include LAT safety, the impact of LAT results on NSCLC treatment plans and non-invasive MRI-derived measures of cardiac function and altered body composition (as alternative explanations for mini-PE). Study progress, including the impact of COVID19 was reviewed and summarised.ResultsSTRATIFY was rapidly halted due to COVID19 after 1 patient was recruited. The study was allowed to reopen in July-20 but given a dramatic reduction in lung cancer referrals across the UK and delayed site set up processes, the study team took the decision to close recruitment from Oct-20 to Apr-21. This was supported by the funder who provided a costed 6-month extension. By June-21, 4/8 sites have opened. 4/6 six screened patients have been recruited, 2/4 have entered the MRI sub-study.ConclusionsSTRATIFY will determine the true prevalence of OPM in patients with radically treatable NSCLC and mini-PE. The study outcomes will be important in defining an extended role for LAT as a pleural staging tool.

Role of inpatient coronary CT angiography on clinical decision making during COVID- 19 pandemic

Background: The COVID-19 pandemic has had a profound effect on healthcare delivery. Here we describe the effect of repurposing of a research Computed Tomography scanner on clinical care of cardiology patients in an urban academic medical centre which did not have routine access to CCTA prior to the pandemic. Patients requiring invasive coronary angiography require transfer to a regional cardiac centre (no ICA available on site). Purpose: We investigated the effect of CCTA on i) diagnostic certainty ii) avoidance of clinician defined unnecessary invasive angiography in hospitalised patients. Methods: This was a prospective, longitudinal cohort study involving hospitalized patients admitted to an urban academic medical centre (catchment population 650 000) between March 29 and September 21, 2020. Routinely collected (usual care) data were gathered by clinicians who were members of the usual care medical team and ethics approval or explicit patient consent was not required. High-sensitivity Troponin-I was measured on admission and 3- and 6- hours after if mandated (Abbott Architect TnI assay). A 320-detector scanner (Aquilon ONE, Canon) was used. Intravenous metoprolol was used where required to control the heart rate (target 60 b.p.m.) and sublingual glyceryl trinitrate will be given to all patients immediately before the scan acquisition. Results: Forty-three patients underwent inpatient CCTA, mean age: 61 ± 13 years (range 30-88y), 54% female. The presenting complaint was typical chest pain in 28 (65%), atypical chest pain in 10 (23%), and a variety of symptoms in 5 (12%) including palpitations, syncope, breathlessness. Thirty-six (84%) of patients had a detectable TnI above the 99% centile. Median(IQR) peak TnI was 127 (33-635)ng/L. CCTA was carried out on average 1 day post request. CCTA resulted in an improvement in clinician diagnostic certainty (Initial review: 21% yes, 79% probable, post-CCTA review: 84% yes, 16% probable) in providing a diagnosis. 21 (49%) of invasive coronary angiograms were avoided due to CCTA, whilst an inpatient invasive coronary angiogram (ICA) was performed in 4(9%) due to CCTA demonstrating significant disease, and in 2(%) the ICA was changed from out-patient to in-patient. Three ICA tests were requested as OP due to CCTA findings. CCTA did not overestimate disease severity in this cohort. We saved 21 inter hospital transfers for ICA during this time period. Using NHS England cost tariffs, a cost saving of >£36,000 was made for using CCTA instead of ICA in these 21 patients who would have required ICA. Conclusion: Inpatient CCTA resulted in greater clinician diagnostic confidence, avoidance of unnecessary invasive angiograms and a significant cost saving. This also reduced the duration of patient stay, reducing the potential exposure of patients to COVID-19. (Table Presented).

Performance of Donor Derived Cell-Free DNA in Routine Clinical Care of Lung Transplant Recipients, a Multi-Center Study

Purpose Prior observational data suggest that donor-derived cell-free DNA (dd-cfDNA) increases in lung transplant acute rejection and infection. The performance of dd-cfDNA in routine clinical care remains undefined. In response to the COVID-19 pandemic, to mitigate the risk of exposing patients to infection, four centers used dd-cfDNA for surveillance instead of surveillance bronchoscopy, providing a unique opportunity to assess the performance of dd-cfDNA in routine clinical care. Methods As part of routine care during the COVID-19 pandemic, four lung transplant centers implemented a home-based surveillance program using plasma dd-cfDNA (Allosure®) in preference to surveillance bronchoscopy. Based on prior data, dd-cfDNA > 1% triggered further work-up including bronchoscopy. dd-cfDNA testing was also performed in response to a decline in forced expiratory volume in 1 second (FEV1), symptoms or treatment follow up. Data was retrospectively analyzed from 4/1/2020 - 9/1/2020 to assess the performance of dd-cfDNA in diagnosing a composite of ACR, AMR and/or infection. Results 169 patients underwent 380 dd-cfDNA measurements over the study period. The mean age was 58.5 years, 54% of patients were male and 82% bilateral lung transplants. 99 (58%) patients were <1 year post-transplant. 327 of 380 dd-cfDNA values were drawn for surveillance reasons. 31 patients had a surveillance level > 1%. Of these, 19/31 (61%) had evidence of ACR, AMR or infection. 115 patients had surveillance levels that remained < 1% over the study period with 109/115 (95%) displaying no clinical evidence of ACR, AMR, infection or decline in FEV1 or symptoms. The remaining 23 patients had levels drawn for clinical indications (non-surveillance). 45 surveillance bronchoscopies were performed with concomitant dd-cfDNA (23 triggered by dd-cfDNA > 1%). For diagnosis of ACR, AMR or infection in these patients, dd-cfDNA > 1% yielded a sensitivity of 84%, specificity of 77%, positive predictive value of 73% and negative predictive value of 87%. Conclusion In this study, dd-cfDNA identified ACR, AMR and/or infection in asymptomatic lung transplant patients that may not have been identified by clinically indicated biopsy alone. Low levels of dd-cfDNA may also be useful in ruling out AMR, ACR and/or infection, supporting its use as a potential non-invasive marker for surveillance monitoring.

Cell-Free DNA Tissue Damage Mapping in Transplant Patients Infected with COVID-19

Purpose Patients with COVID-19 show variable clinical course;transplant patients often show worse outcomes. The effect of COVID-19 on the allograft and the sources of tissue injury that contribute to such poor outcomes are poorly defined. This study leverages cell-free DNA (cfDNA) to measure allograft injury as donor-derived cfDNA (ddcfDNA) and injury from different tissue types using tissue-specific DNA methylomic signatures. Methods 14 consecutive COVID-19 transplant patients (8 Kidney, 3 Lung, 1 Heart, 1 Liver, and one multi-organ transplant patients) and 30 healthy controls were included. Plasma nuclear cfDNA (ncfDNA) and mitochondrial cfDNA (mtcfDNA) level were measured via digital droplet PCR, and ddcfDNA using AlloSure (CareDx). cfDNA whole-genome bisulfite sequencing was performed to identify cfDNA tissues of origin leveraging tissue specific DNA methylomes and deconvolution algorithm. Results 75% of the COVID-19 transplant patients showed high ddcfDNA level compared to published quiescent values, including all lung, 50% of the kidney, liver and multi-organ transplant patients (8.5, 4.4, 30 and 16-X fold change, respectively). Total ncfDNA and mtcfDNA were 15X and 310X higher in COVID-19 transplant patients compared to controls, respectively;< 0.0001.The predominant tissues contributing to cfDNA were hematopoietic cells (80%) (Figure). More importantly, COVID-19 transplant patients showed 10 to 100 fold higher tissue specific cfDNA derived from monocyte, neutrophil, erythroblast, vascular endothelium, adipocyte, hepatocyte, kidney, heart and lung compared to controls. Analysis comparing cfDNA in transplant and non-transplant COVID-19 patients is on-going. Conclusion The allograft undergoes significant injury following COVID-19. Further, cfDNA from multiple tissue types is significantly higher in COVID-19 transplant patients. Future studies in a larger cohorts of transplant and non-transplant patients are needed to elucidate why transplant patients show worse COVID-19 outcomes.