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Background: Long-term outcome of lung transplantation (LTx) recipients is limited by chronic lung allograft dysfunction (CLAD). In this setting of new onset respiratory failure, the amount of oxygenated hemoglobin (OxyHem; hemoglobin (Hb) concentration × fractional oxygen saturation) may provide valuable information. Objective: We hypothesized that OxyHem predicts survival of LTx recipients at the onset of CLAD. Methods: Data from 292 LTx recipients with CLAD were analyzed. After excluding patients with missing data or supplemental oxygen, the final population comprised 218 patients. The relationship between survival upon CLAD and OxyHem was analyzed by Cox regression analyses and ROC curves. Results: Among the 218 patients (102 males, 116 females), 128 (58.7%) died, median survival time after CLAD onset being 1,156 days. Survival was significantly associated with type of transplantation, time to CLAD, CLAD stage at onset, and OxyHem, which was superior to Hb or oxygen saturation. The risk for death after CLAD increased by 14% per reduction of OxyHem by 1 g/dL, and values below 11 g/dL corresponded to an 80% increase in mortality risk. Conclusion: Thus, OxyHem was identified as an independent predictor of mortality after CLAD onset. Whether it is useful in supporting therapeutic decisions and potentially home monitoring in the surveillance of lung transplant recipients has to be studied further.

Purpose To investigate the expression of the receptor protein ACE-2 alongside the urinary tract, urinary shedding and urinary stability of SARS-CoV-2 RNA. Methods Immunohistochemical staining was performed on tissue from urological surgery of 10 patients. Further, patients treated for coronavirus disease (COVID-19) at specialized care-units of a university hospital were assessed for detection of SARS-CoV-2 RNA in urinary samples via PCR, disease severity (WHO score), inflammatory response of patients. Finally, the stability of SARS-CoV-2 RNA in urine was analyzed. Results High ACE-2 expression (3/3) was observed in the tubules of the kidney and prostate glands, moderate expression in urothelial cells of the bladder (0–2/3) and no expression in kidney glomeruli, muscularis of the bladder and stroma of the prostate (0/3). SARS-CoV-2 RNA was detected in 5/199 urine samples from 64 patients. Viral RNA was detected in the first urinary sample of sequential samples. Viral RNA load from other specimen as nasopharyngeal swabs (NPS) or endotracheal aspirates revealed higher levels than from urine. Detection of SARS-CoV-2 RNA in urine was not associated with impaired WHO score (median 5, range 3–8 vs median 4, range 1–8, p = 0.314), peak white blood cell count (median 24.1 × 1000/ml, range 5.19–48.1 versus median 11.9 × 1000/ml, range 2.9–60.3, p = 0.307), peak CRP (median 20.7 mg/dl, 4.2–40.2 versus median 11.9 mg/dl, range 0.1–51.9, p = 0.316) or peak IL-6 levels (median: 1442 ng/ml, range 26.7–3918 versus median 140 ng/ml, range 3.0–11,041, p = 0.099). SARS-CoV-2 RNA was stable under different storage conditions and after freeze–thaw cycles. Conclusions SARS-CoV-2 RNA in the urine of COVID-19 patients occurs infrequently. The viral RNA load and dynamics of SARS-CoV-2 RNA shedding suggest no relevant route of transmission through the urinary tract.

Letermovir is a new antiviral drug approved for the prophylaxis of CMV infection in allogeneic stem cell transplants. The aim of the study was to assess the therapeutic efficacy of letermovir in difficult to treat CMV infections in lung transplant recipients. All lung transplant recipients between March 2018 and August 2020, who have been treated with letermovir for ganciclovir-resistant or refractory CMV infection were included in the study and analysed retrospectively. In total, 28 patients were identified. CMV disease was present in 15 patients (53.6%). In 23 patients (82.1%), rapid response was noticed, and CMV-viral load could be significantly decreased (>1 log10 ) after a median of 17 [14-27] days and cleared subsequently in all of these patients. Five patients (17.9%) were classified as non-responder. Thereof, development of a mutation of the CMV UL56 terminase (UL-56-Gen: C325Y) conferring letermovir resistance could be observed in three patients (60%). Common side effects were mild and mostly of gastrointestinal nature. Mild adjustments of the immunosuppressive drugs were mandatory upon treatment initiation with letermovir. In addition to other interventions, letermovir was effective in difficult to treat CMV infections in lung transplant recipients. However, in patients with treatment failure mutation conferring letermovir, resistance should be taken into account.

Phenotyping chronic lung allograft dysfunction (CLAD) in single lung transplant (SLTX) recipients is challenging. The aim of this study was to assess the diagnostic and prognostic value of longitudinal lung function tests in SLTX recipients with CLAD.A total of 295 SLTX recipients were analyzed and stratified according to native lung physiology. In addition to spirometry, measurements of static lung volumes and lung capacities were used to phenotype patients and to assess their prognostic value. Outcome was survival after CLAD onset. Patients with insufficient clinical information were excluded (n = 71).Of 224 lung transplant recipients, 105 (46.9%) developed CLAD. Time to CLAD onset (hazard ratio [HR]: 0.82, 95% CI: 0.74-0.90; p0.001), severity of CLAD at onset (HR: 0.97, 95% CI: 0.94-0.99; p = 0.009), and progression after onset of CLAD (HR: 1.03, 95% CI: 1.00-1.05; p = 0.023) were associated with outcome. Phenotypes at onset were bronchiolitis obliterans syndrome (BOS) (59.1%), restrictive allograft syndrome (RAS) (12.4%), mixed phenotype (6.7%), and undefined phenotype (21.9%). Survival estimates differed significantly between phenotypes (p = 0.004), with RAS and mixed phenotype being associated with the worst survival, followed by BOS and undefined phenotype. Finally, a higher hazard for mortality was noticed for RAS (HR: 2.34, 95% CI: 0.99-5.52; p = 0.054) and mixed phenotype (HR: 3.30, 95% CI: 1.20-9.11; p = 0.021) while controlling for time to CLAD onset and severity of CLAD at onset.Phenotyping CLAD in SLTX remains challenging with a high number of patients with an undefined phenotype despite comprehensive lung function testing. However, phenotyping is of prognostic value. Furthermore, early, severe, and progressive CLADs are associated with worse survival.

Background The standard treatment of acute cellular rejection after lung transplantation (LTx) is a high-dose steroid pulse therapy. In our center, this therapy is also the standard of care for LTx recipients with acute loss of forced expiratory volume in 1 second (FEV1), after excluding specific causes such as acute rejection on biopsy. The aim of this retrospective study was to evaluate the safety and efficacy of steroid pulse therapy. Methods From 2015 to 2018, 33 consecutive patients (17 male patients, mean age ± SD, 50.5 ± 12.5 years) were included. All patients underwent routine examinations to exclude acute cellular rejection and other specific causes. FEV1 was routinely measured after 5 days, and 1, 3, and 6 months. Positive response to steroid pulse therapy was defined by increase of FEV1 > 10%. Results The mean decrease ± SD from baseline in FEV1 at the start of steroid pulse therapy was 380 ± 630 mL (P = .02). FEV1 changed after 5 days by 170 ± 180 mL (P = .0007), and after 1 month by 140 ± 230 mL (P = .70), 3 months by −60 ± 240 mL (P = .15), and 6 months by −80 ± 290 mL (P = .73). A positive response was observed in 21% of patients after 3 months and 12% after 6 months. High bronchoalveolar lavage (BAL) eosinophil count correlated with a higher FEV1 after steroid pulse therapy. Serious complications were observed in 4 out of 33 patients (12%) with 1 fatal event (pneumonia). Conclusions Only a minority of patients after LTx with loss of FEV1 after exclusion of acute cellular rejection benefit from steroid pulse therapy. Patients with BAL eosinophilia are more likely to respond. However, severe complications were observed.

INTRODUCTION Chronic kidney disease (CKD) is associated with significant morbidity and mortality after lung transplantation (LTX). Calcineurin inhibitor (CNI) nephrotoxicity is the leading cause of CKD. After kidney transplantation, polyomavirus-associated nephropathy (PyVAN) is a well-recognized problem. This study aims to evaluate the role of polyomavirus in patients after LTX. METHODS From January 2017 to January 2020, all lung transplant recipients who performed follow-up visits in our center were included in the study and retrospectively assessed. We measured renal function (creatinine levels before and after transplantation), JCPyV, and BKPyV load by polymerase chain reaction (PCR) in serum and urine samples after transplantation. RESULTS In total, 104 consecutive patients (59 males, 56.7%) with a mean age of 49.6 ± 11.1 years were identified. JCPyV was found in urine of 36 patients (34.6%) and serum of 3 patients (2.9%). BKPyV was found in urine of 40 patients (38.5%) and serum of 4 patients (3.8%), respectively. Urine evidence for JCPyV (p

Coronary artery disease (CAD) is associated with increased mortality in patients with chronic lung disease. However, non-invasive diagnostic of CAD is difficult, especially in patients with more advanced disease. Therefore, we aimed to assess the feasibility and accuracy of SPECT-myocardial perfusion imaging (MPI) stress testing with regadenoson in patients with end-stage lung disease (ELD) undergoing assessment of stable CAD. Between January 2012 and May 2018, 102 patients with ELD, who were referred to our institution for lung transplant evaluation, were assessed retrospectively. All patients underwent both stress SPECT-MPI as well as coronary angiography. The mean age in our population was 57±6 years. All patients had severe pulmonary function impairment. During stress SPECT-MPI 14 patients (14%) reported regadenoson-related symptoms, but only 2 patients (2%) required medical treatment. Coronary angiography revealed obstructive CAD in 20 patients (20%). Among those, 5 patients had abnormal SPECT-MPI and PCI was performed in 3 patients accordingly. In 14 patients with obstructive CAD, revascularization was deferred based on normal SPECT-MPI findings. SPECT-MPI using regadenoson is well tolerated in patients with ELD and can help to make decisions about coronary revascularization before lung transplant.

Pirfenidone demonstrated pleiotropic antiinflammatory effects in various experimental and clinical settings. The aim of this study was to assess the impact of previous treatment with pirfenidone on short-term outcomes after single lung transplantation (SLTx). Therefore, patients with idiopathic pulmonary fibrosis (IPF) who were undergoing SLTx were screened retrospectively for previous use of pirfenidone and compared to respective controls. Baseline parameters and short-term outcomes were recorded and analyzed. In total, 17 patients with pirfenidone were compared with 26 patients without antifibrotic treatment. Baseline characteristics and severity of disease did not differ between groups. Use of pirfenidone did not increase blood loss, wound-healing, or anastomotic complications. Severity of primary graft dysfunction at 72 hours was less (0.3 ± 0.6 vs 1.4 ± 1.3, P = .002), and length of mechanical ventilation (37.5 ± 34.8 vs 118.5 ± 151.0 hours, P = .016) and intensive care unit (ICU) stay (6.6 ± 7.1 vs 15.6 ± 20.3, P = .089) were shorter in patients with pirfenidone treatment. An independent beneficial effect of pirfenidone was confirmed by regression analysis while controlling for confounding variables (P = .016). Finally, incidence of acute cellular rejections within the first 30 days after SLTx was lower in patients with previous pirfenidone treatment (0.0% vs 19.2%; P = .040). Our data suggest a beneficial role of previous use of pirfenidone in patients with IPF who were undergoing SLTx.

Background Protecting against CMV infection and maintaining CMV in latent state are largely provided by CMV-specific T-cells in lung transplant recipients. The aim of the study was to assess whether a specific T-cell response is associated with the risk for CMV infection in seronegative patients who are at high risk for delayed CMV infection. Methods All CMV-seronegative recipients (R-) from CMV-seropositive donors (D+) between January 2018 and April 2019 were included and retrospectively screened for CMV infection before and after assessment of CMV-specific cell-mediated immunity. Results Thirty-one of the 50 patients (62%) developed early-onset CMV infection. Lower absolute neutrophil counts were significantly associated with early-onset CMV infection. Antiviral prophylaxis was ceased after 137.2 ± 42.8 days. CMV-CMI were measured at a median of 5.5 months after LTx. 19 patients experienced early and late-onset CMV infection after prophylaxis withdrawal within 15 months post transplantation. Positive CMV-CMI was significantly associated with lower risk of late-onset CMV infection after transplantation in logistic and cox-regression analysis (OR=0.05, p = .01; OR=2,369, p = .026). Conclusion D+/R- lung transplant recipients are at high risk of developing early and late-onset CMV infection. Measurement of CMV-CMI soon after transplantation might further define the CMV infection prediction risk in LTx recipients being at high risk for CMV viremia.

Background In the SARS-CoV-2 pandemic, viral genomes are available at unprecedented speed, but spatio-temporal bias in genome sequence sampling precludes phylogeographical inference without additional contextual data. Aim We applied genomic epidemiology to trace SARS-CoV-2 spread on an international, national and local level, to illustrate how transmission chains can be resolved to the level of a single event and single person using integrated sequence data and spatio-temporal metadata. Methods We investigated 289 COVID-19 cases at a university hospital in Munich, Germany, between 29 February and 27 May 2020. Using the ARTIC protocol, we obtained near full-length viral genomes from 174 SARS-CoV-2-positive respiratory samples. Phylogenetic analyses using the Auspice software were employed in combination with anamnestic reporting of travel history, interpersonal interactions and perceived high-risk exposures among patients and healthcare workers to characterise cluster outbreaks and establish likely scenarios and timelines of transmission. Results We identified multiple independent introductions in the Munich Metropolitan Region during the first weeks of the first pandemic wave, mainly by travellers returning from popular skiing areas in the Alps. In these early weeks, the rate of presumable hospital-acquired infections among patients and in particular healthcare workers was high (9.6% and 54%, respectively) and we illustrated how transmission chains can be dissected at high resolution combining virus sequences and spatio-temporal networks of human interactions. Conclusions Early spread of SARS-CoV-2 in Europe was catalysed by superspreading events and regional hotspots during the winter holiday season. Genomic epidemiology can be employed to trace viral spread and inform effective containment strategies.

Objective Evaluation of pulmonary function impairment after COVID-19 in persistently symptomatic and asymptomatic patients of all disease severities and characterisation of risk factors. Methods Patients with confirmed SARS-CoV-2 infection underwent prospective follow-up with pulmonary function testing and blood gas analysis during steady-state cycle exercise 4 months after acute illness. Pulmonary function impairment (PFI) was defined as reduction below 80% predicted of DLCOcSB, TLC, FVC, or FEV1. Clinical data were analyzed to identify risk factors for impaired pulmonary function. Results 76 patients were included, hereof 35 outpatients with mild disease and 41 patients hospitalized due to COVID-19. Sixteen patients had critical disease requiring mechanical ventilation, 25 patients had moderate–severe disease. After 4 months, 44 patients reported persisting respiratory symptoms. Significant PFI was prevalent in 40 patients (52.6%) occurring among all disease severities. The most common cause for PFI was reduced DLCOcSB (n = 39, 51.3%), followed by reduced TLC and FVC. The severity of PFI was significantly associated with mechanical ventilation (p p p = 0.014) and in hospitalized patients CT score. A decrease of paO2 > 3 mmHg during cycle exercise occurred in 1/5 of patients after mild disease course. Conclusion We characterized pulmonary function impairment in asymptomatic and persistently symptomatic patients of different severity groups of COVID-19 and identified further risk factors associated with persistently decreased pulmonary function. Remarkably, gas exchange abnormalities were revealed upon cycle exercise in some patients with mild disease courses and no preexisting pulmonary condition.

A fraction of COVID-19 patients progress to a severe disease manifestation with respiratory failure and the necessity of mechanical ventilation. Identifying patients at risk is critical for optimized care and early therapeutic interventions. We investigated the dynamics of SARS-CoV-2 shedding relative to disease severity. We analyzed nasopharyngeal and tracheal shedding of SARS-CoV-2 in 92 patients with diagnosed COVID-19. Upon admission, standardized nasopharyngeal swabs or sputum were collected. If patients were mechanically ventilated, tracheal aspirates were additionally obtained. Viral shedding was quantified by real-time PCR detection of SARS-CoV-2 RNA. 45% (41 of 92) of COVID-19 had a severe disease course with the need for mechanical ventilation (severe group). At week 1, the initial viral shedding determined from nasopharyngeal swabs showed no significant difference between non-severe and severe cases. At week 2, a difference could be observed as the viral shedding remained elevated in severely ill patients. A time course of C-reactive-Protein (CRP), Interleukin-6 (Il-6), and Procalcitonin (PCT) revealed an even more protracted inflammatory response following the delayed drop of virus shedding load in severely ill patients. A significant proportion (47.8%) of patients showed evidence of prolonged viral shedding (>17 days), which was associated with severe disease courses (73.2%). We report that viral shedding does not differ significantly between severe and non-severe cases upon admission to the hospital. Elevated SARS-CoV-2 shedding in the second week of hospitalisation, a systemic inflammatory reaction peaking between second and third week and prolonged viral shedding are associated with a more severe disease course., We report that elevated SARS-CoV-2 shedding in the second week of hospitalisation, a systemic inflammatory reaction peaking between second and third week and prolonged viral shedding are associated with a more severe disease course.

Background Biological treatments directed against IgE and IL-5 have largely improved outcomes for patients with severe type 2–high asthma. However, a fraction of patients with severe asthma show insufficient treatment outcome under anti-IgE and anti–IL-5/IL-5 receptor α antibodies. Objective To evaluate whether switching to dupilumab was of benefit in patients with insufficient outcome under previous anti-IgE or anti–IL-5/IL-5 receptor α therapy. Methods We retrospectively analyzed 38 patients who were switched to dupilumab from a previous anti-IgE or anti–IL-5/IL-5 receptor α medication because of insufficient outcome. We defined response criteria after 3 to 6 months as an improvement in at least 1 of the following criteria without deterioration in the other criteria, comparing values under dupilumab with values under previous antibody therapy: (1) increase of 3 or more in Asthma Control Test score, (2) 50% or more reduction in oral corticosteroid dose, and (3) FEV1 improvement greater than or equal to 150 mL, and classified patients as responders and nonresponders. Results Switch to dupilumab led to a response in 76% of patients. In the total cohort, Asthma Control Test score increased by a mean of 2.9 (P Conclusions Altogether, we show that a switch to dupilumab in patients with insufficient outcome under previous biological therapy was effective in most patients.

Background Anti-fibrotic drugs may interfere with wound-healing after major surgery, theoretically preventing sufficient bronchial anastomosis formation after lung transplantation (LTx). The aim of this study was to assess the impact of previous treatment with pirfenidone and nintedanib on outcomes after LTx in patients with idiopathic pulmonary fibrosis (IPF). Methods All patients with IPF undergoing LTx at the University of Munich between January 2012 and November 2016 were retrospectively screened for previous use of anti-fibrotics. Post-transplant outcome and survival of patients with and without anti-fibrotic treatment were analyzed. Results A total of 62 patients with IPF were transplanted (lung allocation score [mean ± SD] 53.1 ± 16.1). Of these, 23 (37.1%) received pirfenidone and 7 (11.3%) received nintedanib before LTx; the remaining 32 (51.6%) did not receive any anti-fibrotic drug (control group). Patients receiving anti-fibrotics were significantly older (p = 0.004) and their carbon monoxide diffusion capacity was significantly higher ( p = 0.008) than in controls. Previous anti-fibrotic treatment did not increase blood product utilization, wound-healing or anastomotic complications after LTx. Post-transplant surgical revisions due to bleeding and/or impaired wound-healing were necessary in 18 (29.0%) patients (pirfenidone 30.4%, nintedanib 14.3%, control 31.3%; p = 0.66). Anastomosis insufficiency occurred in 2 (3.2%) patients, both in the control group. No patient died within the first 30 days post-LTx, and no significant differences regarding survival were seen during the follow-up (12-month survival: pirfenidone 77.0%, nintedanib 100%, control 90.6%; p = 0.29). Conclusion Our data show that previous use of anti-fibrotic therapy does not increase surgical complications or post-operative mortality after LTx.

Background Cytomegalovirus (CMV)-infection remains a major cause of morbidity and mortality after lung transplantation. Treatment with currently available drugs poses treatment difficulties in some patients due to drug resistance or intolerability. Methods We report a series of 4 lung transplant recipients with CMV-infection and treatment failure upon standard care due to antiviral drug resistance and treatment-limiting side effects. As rescue therapy letermovir recently approved for the prophylaxis of CMV-infection in patients after hematopoietic stem cell transplantation was initiated. Patients received 480 mg/day for a follow up of 36.1 ± 12.9 weeks. Efficacy and tolerability were assessed retrospectively. Results Mild nausea, vomiting, and diarrhea were the only side effects of letermovir reported by a single patient. A small adjustment of the tacrolimus dose was mandatory upon treatment initiation with letermovir. CMV viral load could be decreased and cleared subsequently in all patients. CMV clearance was observed after 17.7 ± 12.6 weeks despite lack of CMV-immunity. Conclusions CMV-infection and -disease were successfully managed with letermovir. Letermovir was well tolerated and effective in treating CMV-infections in lung transplant recipients failing on currently available antiviral agents.

The standard treatment of acute cellular rejection after lung transplantation (LTx) is a high-dose steroid pulse therapy. In our center, this therapy is also the standard of care for LTx recipients with acute loss of forced expiratory volume in 1 second (FEVFrom 2015 to 2018, 33 consecutive patients (17 male patients, mean age ± SD, 50.5 ± 12.5 years) were included. All patients underwent routine examinations to exclude acute cellular rejection and other specific causes. FEVThe mean decrease ± SD from baseline in FEVOnly a minority of patients after LTx with loss of FEV

Tobacco use after lung transplantation is associated with adverse outcome. Therefore, active smoking is regarded as a contraindication for lung transplantation and should be excluded prior to placement on the waiting list. The aim of the study was to compare self-reporting with a systematic cotinine based screening approach to identify patients with active nicotine abuse. Nicotine use was systematically assessed by interviews and cotinine test in all lung transplant candidates at every visit in our center. Patients were classified according to the stage prior to transplantation and cotinine test results were compared to self-reports and retrospectively analyzed until June 2019. Of 620 lung transplant candidates, 92 patients (14.8%) had at least one positive cotinine test. COPD as underlying disease (OR 2.102, CI 1.110-3.981; p = 0.023), number of pack years (OR 1.014, CI 1.000-1.028; p = 0.047) and a time of cessation less than one year (OR 2.413, CI 1.410-4.128; p = 0.001) were associated with a positive cotinine test in multivariable regression analysis. The majority of non-COPD patients (n = 13, 72.2%) with a positive test had a cessation time of less than one year. 78 patients (84.7%) falsely declared not consuming any nicotine-based products prior to the test. Finally, all never smokers were test negative. In conclusion, our data demonstrate that active nicotine use is prevalent in transplant candidates with a high prevalence of falsely declaring nicotine abstinence. COPD was the main diagnosis in affected patients. Short cessation time and a high number of pack years are risk factors for continued nicotine abuse.

Aim: Biological therapies developed for severe asthma may have a role in COPD patients with asthma features.Method: We carried out a prospective, consecutive, cross-sectional analysis of 80 patients with severe COPD GOLD IV/D.Results: We studied 80 patients (48.8% female), aged 57.6 +/- 5.1 years, ex-smokers with 35.7 +/- 21.2 pack years, BMI 22.3 +/- 3.5 kg/m(2), FEV1 of 0.61 +/- 0.2 L (21.1 +/- 5.6% pred), pO(2) 52.4 +/- 8.4 mmHg, and BODE 6.9 +/- 1.7. 68% had > 2 moderate or severe exacerbations annually. 16.1% (5/31) patients showed FEV1 reversibility of > 12% and > 200 ml despite maximal therapy, 33% (15/45) had FENO >= 22.5 ppb, 33% (24/73) had serum IgE >= 100 I.E./ml and there was positive allergen sensitization in 51.5% (35/68). Blood eosinophilia of >= 150 cells/mu l was seen in 47% (35/74). Induced sputum showed eosinophilia of >= 2% in 56% (14/24) with respiratory pathogens in 63.8% (30/47). We identified 12 (15%) patients with asthma-COPD overlap. Of these, 10 (83.3%) had frequent exacerbations and these patients had significantly more severe exacerbations requiring NIV or ICU than those without asthma features (p < 0.005).Conclusion: We detected asthma features in a substantial subset of stable patients with severe COPD. Asthma features were associated with more severe exacerbation despite optimal COPD therapy, representing potential candidates for targeted therapy with anti- IgE or anti-IL5.

Dendritic cell (DC) vaccination is considered a promising immunotherapeutic strategy for AML patients with minimal residual disease (MRD). We have developed a three-day manufacturing protocol containing a synthetic TLR7/8 agonist to generate DCs with a positive costimulatory profile and high IL-12p70 secretion (TLR-DCs). These proved to be superior with respect to type 1 polarization of T cells and activation of NK cells compared to conventional monocyte-derived DCs. In an attempt to further optimize the maturation protocol, we compared the use of standard pooled human serum (PHS) with autologous human serum (AHS) from healthy donors (HDs, n=16) and AML patients (n=6) within the generation process of TLR-DCs. Surprisingly, we found that AHS-DCs from HDs were significantly inferior to PHS-DCs concerning viability (81% vs. 91%, p=0.002) and recovery (3.8% vs. 7.1%, p=0.037) after the maturation process. A similar effect was seen in AHS-DCs from AML patients. In a functional analysis, IL-12p70 secretion was reduced and migratory capacity of the DCs to CCL19 was impaired. We are currently working on the identification of immunomodulatory components within the AHS that are responsible for these detrimental effects. In a preliminary cytokine analysis, we found that pro-inflammatory (TNF-α) as well as anti-inflammatory (IL-10) cytokines were significantly increased in the AHS samples. PHS is therefore highly recommendable for the maturation process and was used in all subsequent experiments. With this protocol, we were able to show that TLR-DCs can also be generated from monocytes of AML patients. No differences in phenotype and function were found compared to samples from healthy blood donors. Efficient and controllable expression of leukemia-associated antigens was induced by RNA electroporation. These cells are capable of both priming naïve T cells and reactivating antigen-specific pre-primed effector cells in vitroand are therefore highly suitable for DC vaccination strategies in the setting of postremission AML. In order to further enhance the immunostimulatory capacity of TLR-DCs, we are currently evaluating combinatorial approaches with inhibitors of receptor-ligand immune checkpoints. Their high therapeutic potential has recently been demonstrated for various tumor entities. In a comprehensive analysis of immune checkpoint molecules, it was revealed that TLR-DCs, albeit showing a preferentially positive costimulatory profile, express significant amounts of immunoinhibitory molecules from different families (PD-L1, B7-H3, HVEM, ILT3, ILT4, 4-1BBL). We have set up an ex vivo coculture system for activation and expansion of T cells by autologous DCs. Using blocking antibodies against PD-1, we could demonstrate a significant increase of IFN-γ secretion by T cells in samples of healthy donors and HIV patients as well as AML patients. The ultimate goal is to figure out which combination of immune checkpoint inhibitors is the most appropriate to increase the effect of a DC-based immunotherapy in the clinical setting of AML immunotherapy. Disclosures: No relevant conflicts of interest to declare.