2-Step-Scores with optional nephropathology for the prediction of adverse outcomes for brain-dead donor kidneys in Eurotransplant.

BACKGROUND AND HYPOTHESIS: The decision for acceptance or discard of the increasingly rare and marginal brain-dead donor kidneys in Eurotransplant (ET) countries has to be made without solid evidence. Thus, we developed and validated flexible clinicopathological scores called 2-Step Scores for the prognosis of delayed graft function (DGF) and one-year death-censored transplant loss (1y-tl) reflecting the current practice of six ET countries including Croatia and Belgium. METHODS: The training set was n=620 for DGF and n=711 for 1y-tl, with validation sets n=158 and n=162. In step 1, stepwise logistic regression models including only clinical predictors were used to estimate the risks. In step 2, risk estimates were updated for statistically relevant intermediate risk percentiles with nephropathology. RESULTS: Step 1 revealed an increased risk of DGF with increased cold ischaemia time, donor and recipient BMI, dialysis vintage, number of HLA-DR mismatches or recipient CMV IgG positivity. On the training and validation set, c-statistics were 0.672 and 0.704, respectively. At a range between 18% and 36%, accuracy of DGF-prognostication improved with nephropathology including number of glomeruli and Banff cv (updated overall c statistics of 0.696 and 0.701, respectively).Risk of 1y-tl increased in recipients with cold ischaemia time, sum of HLA-A. -B, -DR mismatches and donor age. On training and validation sets, c-statistics were 0.700 and 0.769, respectively. Accuracy of 1y-tl prediction improved (c-statistics = 0.706 and 0.765) with Banff ct. Overall, calibration was good on the training, but moderate on the validation set; discrimination was at least as good as established scores when applied to the validation set. CONCLUSION: Our flexible 2-Step Scores with optional inclusion of time-consuming and often unavailable nephropathology should yield good results for clinical practice in ET, and may be superior to established scores. Our scores are adaptable to donation after cardiac death and perfusion pump use.

COVID-19-associated secondary sclerosing cholangitis with liver transplantation.

We report on two cases of orthotopic liver transplantation (OLTX) due to SARS-Cov2-associated secondary sclerosing cholangitis (SSC) following long-term artificial respiration and extra-corporal membrane oxygenation in intensive care. Under these conditions, SSC is a rapidly progredient biliary disease featuring degenerative cholangiopathy, loss of bile ducts, ductular and parenchymal cholestasis, biliary fibrosis, and finally cirrhosis. Reduced perfusion and oxygenation of the peribiliary plexus, severe concurrent infections, and secondary medico-toxic effects appear to play a crucial role in the pathogenesis of the disease. A direct cytopathic effect of SARS-Cov2 on endothelial cells followed by thrombosis and fibrosing obliteration in all parts of the vascular bed of the liver may enhance the virus-associated liver disease and particularly SSC.

Five-year single-center analysis of cytomegalovirus viremia in kidney transplant recipients and possible implication for novel prophylactic therapy approaches.

BACKGROUND: Cytomegalovirus (CMV) infections are a common complication after kidney transplantation (KTx) and negatively affecting patient outcome. Valganciclovir (VGC) prophylaxis is often limited by drug-induced side effects and dose reduction due to decline in kidney function. METHOD: In the present study, episodes of CMV viremia in the first year after KTx in a cohort of 316 recipients were analyzed retrospectively to identify risk factors linked to persistent infections. RESULTS: In the studied cohort, 18.7% of patients showed a high-risk (HR) constellation (D+/R-) for CMV infections. CMV viremia affected 22% of our cohort, with HR patients being the most affected cohort (44.1%). Within this group, most viremic events (65.3%) occurred while patients were still on prophylactic therapy, showing significantly higher viral loads and a longer duration compared to seropositive recipients. CONCLUSION: The analysis at hand revealed that detection of viremia under ongoing antiviral prophylaxis bears an increased risk for sustained viral replication and antiviral drug resistance in HR patients. We identified low estimated glomerular filtration rate (eGFR) and lower dose VGC prophylaxis post-KTx as a risk factor for breakthrough infections in HR patients in our single center cohort. These patients might benefit from a closer CMV monitoring or novel prophylactic agents as letermovir.

The Impact of the COVID Pandemic on Adrenal Surgery at an Academic Endocrine Surgery Unit.

COVID-19 has severely affected the delivery of surgical care worldwide. The aim of the present study was to evaluate its impact on adrenal surgery at our academic endocrine center. All primary adrenal surgeries performed at the University Hospital of Cologne, Germany between 01.01.2019 and 31.07.2022 were included. This time frame was divided into pre-Covid (before 02/20), acute Covid (until 05/21), and post acute period (after 05/2021). Demographics, clinic-pathologic characteristics and treatment of these patients were analyzed. One hundred adrenalectomies were included: 22 before, 30 during, and 48 after the acute phase. The percentage of Conn adenomas and pheochromocytomas decreased during the acute phase (from 45.4 to 26.6% and from 18 to 10%, respectively) in favor of Cushing adenomas and suspicious tumors (from 4.5 to 20% and from 31.8 to 36.6%). About 90.9% of tumors resected for suspicion of malignancy were confirmed malignant by final histopathology, as opposed to 71.4% and 52.6% before and after the acute phase. The operative technique was similar during the three phases (63% retroperitoneoscopic, 34% laparoscopic and 2% open resections), with a significantly shorter operative time for retroperitoneoscopy (p=0.04). ICU monitoring demand increased during the acute phase (from 13.6% to 43.3%), according to the increase in Cushing adenomas and malignant tumors. During the acute phase of COVID-19 pandemic adrenal surgery for Cushing and malignant tumors increased, while a delay in pheochromocytoma surgery to the post acute phase was observed. The suspicion of malignancy formulated by the endocrine tumor board was accurate in 90.9% of cases.

High RIPK3 expression is associated with a higher risk of early kidney transplant failure.

Renal ischemia-reperfusion injury (IRI) is associated with reduced allograft survival, and each additional hour of cold ischemia time increases the risk of graft failure and mortality following renal transplantation. Receptor-interacting protein kinase 3 (RIPK3) is a key effector of necroptosis, a regulated form of cell death. Here, we evaluate the first-in-human RIPK3 expression dataset following IRI in kidney transplantation. The primary analysis included 374 baseline biopsy samples obtained from renal allografts 10 minutes after onset of reperfusion. RIPK3 was primarily detected in proximal tubular cells and distal tubular cells, both of which are affected by IRI. Time-to-event analysis revealed that high RIPK3 expression is associated with a significantly higher risk of one-year transplant failure and prognostic for one-year (death-censored) transplant failure independent of donor and recipient associated risk factors in multivariable analyses. The RIPK3 score also correlated with deceased donation, cold ischemia time and the extent of tubular injury.

Imaged guided surgery during arteriovenous malformation of gastrointestinal stromal tumor using hyperspectral and indocyanine green visualization techniques: A case report.

BACKGROUND: This case report demonstrates the simultaneous development of a gastrointestinal stromal tumour (GIST) with arteriovenous malformations (AVMs) within the jejunal mesentery. A 74-year-old male presented to the department of surgery at our institution with a one-month history of abdominal pain. Contrast-enhanced computed tomography revealed an AVM. During exploratory laparotomy, hyperspectral imaging (HSI) and indocyanine green (ICG) fluorescence were used to evaluate the extent of the tumour and determine the resection margins. Intraoperative imaging confirmed AVM, while histopathological evaluation showed an epithelioid, partially spindle cell GIST. CASE SUMMARY: This is the first case reporting the use of HSI and ICG to image GIST intermingled with an AVM. The resection margins were planned using intraoperative analysis of additional optical data. Image-guided surgery enhances the clinician's knowledge of tissue composition and facilitates tissue differentiation. CONCLUSION: Since image-guided surgery is safe, this procedure should increase in popularity among the next generation of surgeons as it is associated with better postoperative outcomes.

Oligometastatic disease and visceral resections in advanced malignant melanoma: a propensity-matched analysis.

PURPOSE: Malignant melanoma is among the tumours with the highest increase in incidence of solid tumours in Germany. While most patients are diagnosed at an early stage and show a good prognosis, advanced stages of malignant melanoma are accompanied with a poor prognosis and limited treatment options. Comparable to other tumour entities, the resection of visceral metastases could lead to a better prognosis. Supplementary, the subgroup of oligometastatic patients might benefit from surgical therapy to a greater extent. METHODS: This retrospective study analysed 351 patients treated between 2006 and 2017 at the University Hospital of Cologne. A total of 121 patients showed visceral metastases, with which we compared patients with a diffuse tumour spread to patients in an oligometastatic state. Furthermore, we evaluated the effect of visceral resection of oligometastatic, malignant melanoma. RESULTS: Our analysis showed that patients with an oligometastatic malignant melanoma had a significantly better prognosis than patients with a diffuse pattern of metastases, if they showed visceral metastases. Furthermore, the resection of visceral metastases leads to a significant gain in median overall survival time (13.6 vs. 34.2 months) and in progression-free survival (9.6 vs. 3.8 months). CONCLUSION: The resection of visceral metastases is a rational treatment option in advanced malignant melanoma. Although our study is limited by a small cohort of patients (n = 18), we believe that the resection of visceral metastases will be fundamental in the treatment of malignant melanoma. In particular, patients in an oligometastatic stage could be an eligible group for surgical treatment.

Feasibility and Potential of Transcriptomic Analysis Using the NanoString nCounter Technology to Aid the Classification of Rejection in Kidney Transplant Biopsies.

BACKGROUND: Transcriptome analysis could be an additional diagnostic parameter in diagnosing kidney transplant (KTx) rejection. Here, we assessed feasibility and potential of NanoString nCounter analysis of KTx biopsies to aid the classification of rejection in clinical practice using both the Banff-Human Organ Transplant (B-HOT) panel and a customized antibody-mediated rejection (AMR)-specific NanoString nCounter Elements (Elements) panel. Additionally, we explored the potential for the classification of KTx rejection building and testing a classifier within our dataset. METHODS: Ninety-six formalin-fixed paraffin-embedded KTx biopsies were retrieved from the archives of the ErasmusMC Rotterdam and the University Hospital Cologne. Biopsies with AMR, borderline or T cell-mediated rejections (BLorTCMR), and no rejection were compared using the B-HOT and Elements panels. RESULTS: High correlation between gene expression levels was found when comparing the 2 chemistries pairwise (r = 0.76-0.88). Differential gene expression (false discovery rate; P < 0.05) was identified in biopsies diagnosed with AMR (B-HOT: 294; Elements: 76) and BLorTCMR (B-HOT: 353; Elements: 57) compared with no rejection. Using the most predictive genes from the B-HOT analysis and the Element analysis, 2 least absolute shrinkage and selection operators-based regression models to classify biopsies as AMR versus no AMR (BLorTCMR or no rejection) were developed achieving an receiver-operating-characteristic curve of 0.994 and 0.894, sensitivity of 0.821 and 0.480, and specificity of 1.00 and 0.979, respectively, during cross-validation. CONCLUSIONS: Transcriptomic analysis is feasible on KTx biopsies previously used for diagnostic purposes. The B-HOT panel has the potential to differentiate AMR from BLorTCMR or no rejection and could prove valuable in aiding kidney transplant rejection classification.

Immune Response to Third and Fourth COVID-19 Vaccination in Hemodialysis Patients and Kidney Transplant Recipients.

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is a serious hazard for hemodialysis (HD) patients and kidney transplant (KTX) recipients as they suffer from an impaired immune response to SARS-CoV-2 vaccination. In addition, a definition of SARS-CoV-2 IgG titer that indicates a sufficient immune response, especially against new omicron variants, is urgently needed. In the present study, the immune response to either a third or a fourth dose of a mRNA vaccine was investigated in 309 dialysis and 36 KTX patients. SARS-CoV-2 IgG titer thresholds indicating neutralizing activity against wild type (WT) and the omicron variant BA.1 were quantified. After four vaccine doses, a high-neutralizing activity against WT was evidenced in HD patients, whereas the neutralizing rate against BA.1 was significant lower. Concerning KTX recipients, humoral and cellular immune responses after a third vaccination were still highly impaired. This calls for modified omicron-targeting vaccines.

[Incidental Finding of Appendiceal Neuroendocrine Tumour]. / Zufallsbefund NEN Appendix.

With an incidence of 80%, neuroendocrine neoplasia (NEN) is the most common neoplasia of the appendix. In most cases, these tumours are diagnosed as an incidental finding after appendectomy with suspected appendicitis. They are usually highly differentiated neuroendocrine tumours. Due to their frequent location on the apex of the appendix, the NENs of the appendix are usually not the cause of the symptoms typical for appendicitis.Most patients (80-90%) receive adequate oncological treatment by laparoscopic or open appendectomy that has already been performed. However, if there are risk factors such as tumour size > 2 cm, location close to the base, angioinvasion, perforation or infiltration of neighbouring organs, proliferation index of > 2% or infiltration of the mesoappendix by more than 3 mm in the final histopathological finding, subsequent resection as an oncological right sided hemicolectomy is recommended .Due to their mostly early tumour stage at diagnosis without proven lymph node metastasis, patients with NEN of the appendix have an excellent 5-year survival rate of 70-85% across all tumour stages.

Post-transplant Malignancies Show Reduced T-cell Abundance and Tertiary Lymphoid Structures as Correlates of Impaired Cancer Immunosurveillance.

PURPOSE: An increased risk to develop cancer is one of the most challenging negative side effects of long-term immunosuppression in organ transplant recipients and impaired cancer immunosurveillance is assumed as underlying mechanism. This study aims to elucidate transplant-related changes in the tumor immune microenvironment (TME) of cancer. EXPERIMENTAL DESIGN: Data from 123 organ transplant recipients (kidney, heart, lung, and liver) were compared with historic data from non-immunosuppressed patients. Digital image analysis of whole-section slides was used to assess abundance and spatial distribution of T cells and tertiary lymphoid structures (TLS) in the TME of 117 tumor samples. Expression of programmed cell death 1 ligand 1 (PD-L1) and human-leucocyte-antigen class I (HLA-I) was assessed on tissue microarrays. RESULTS: We found a remarkably reduced immune infiltrate in the center tumor (CT) regions as well as the invasive margins (IM) of post-transplant cancers. These differences were more pronounced in the IM than in the CT and larger for CD8+ T cells than for CD3+ T cells. The Immune-score integrating results from CT and IM was also lower in transplant recipients. Density of TLS was lower in cancer samples of transplant recipients. The fraction of samples with PD-L1 expression was higher in controls whereas decreased expression of HLA-I was more common in transplant recipients. CONCLUSIONS: Our study demonstrates the impact of immunosuppression on the TME and supports impaired cancer immunosurveillance as important cause of post-transplant cancer. Modern immunosuppressive protocols and cancer therapies should consider the distinct immune microenvironment of post-transplant malignancies.

Kidney Transplantation After Rescue Allocation-the Eurotransplant Experience: A Retrospective Multicenter Outcome Analysis.

BACKGROUND: At Eurotransplant (ET), kidneys are transferred to "rescue allocation" (RA), whenever the standard allocation (SA) algorithms Eurotransplant Kidney Allocation System (ETKAS) and Eurotransplant Senior Program (ESP) fail. We analyzed the outcome of RA. METHODS: Retrospective patient clinical and demographic characteristics association analyses were performed with graft outcomes for 2422 recipients of a deceased donor renal transplantation (DDRT) after RA versus 25 481 after SA from 71 centers across all ET countries from 2006 to 2018. RESULTS: Numbers of DDRTs after RA increased over the time, especially in Germany. RA played a minor role in ESP versus ETKAS (2.7% versus 10.4%). RA recipients and donors were older compared with SA recipients and donors, cold ischemia times were longer, waiting times were shorter, and the incidence of primary nonfunction was comparable. Among ETKAS recipients, HLA matching was more favorable in SA (mean 3.7 versus 2.5). In multivariate modeling, the incidence of graft loss in ETKAS recipients was reduced in RA compared with SA (subdistribution hazard ratio, 0.80; 95% confidence interval [0.70-0.91], P < 0.001), whereas other outcomes (mortality, death with functioning graft (DwFG)) were not significantly different. None of the 3 outcomes were significantly different when comparing RA with SA within the ESP program. CONCLUSIONS: Facing increased waiting times and mortality on dialysis due to donor shortage, this study reveals encouragingly positive DDRT outcomes following RA. This supports the extension of RA to more patients and as an alternative tool to enable transplantation in patients in countries with prohibitively long waiting times or at risk of deterioration.

Gender benefit in laparoscopic surgical performance using a 3D-display system: data from a randomized cross-over trial.

BACKGROUND: The use of 3D technique compared to high-resolution 2D-4K-display technique has been shown to optimize spatial orientation and surgical performance in laparoscopic surgery. Since women make up an increasing amount of medical students and surgeons, this study was designed to investigate whether one gender has a greater benefit from using a 3D compared to a 4K-display system. METHODS: In a randomized cross-over trial, the surgical performance of male and female medical students (MS), non-board certified surgeons (NBCS), and board certified surgeons (BCS) was compared using 3D- vs. 4K-display technique at a minimally invasive training parkour with multiple surgical tasks and repetitions. RESULTS: 128 participants (56 women, 72 men) were included. Overall parkour time in seconds was 3D vs. 4K for all women 770.7 ± 31.9 vs. 1068.1 ± 50.0 (p < 0.001) and all men 664.5 ± 19.9 vs. 889.7 ± 31.2 (p < 0.001). Regarding overall mistakes, participants tend to commit less mistakes while using the 3D-vision system, showing 10.2 ± 1.1 vs. 13.3 ± 1.3 (p = 0.005) for all women and 9.6 ± 0.7 vs. 12.2 ± 1.0 (p = 0.001) for all men. The benefit of using a 3D system, measured by the difference in seconds, was for women 297.3 ± 41.8 (27.84%) vs. 225.2 ± 23.3 (25.31%) for men (p = 0.005). This can be confirmed in the MS group with 327.6 ± 65.5 (35.82%) vs. 249.8 ± 33.7 (32.12%), p = 0.041 and in the NBCS group 359 ± 52.4 (28.25%) vs. 198.2 ± 54.2 (18.62%), p = 0.003. There was no significant difference in the BCS group. CONCLUSION: 3D laparoscopic display technique optimizes surgical performance compared to the 2D-4K technique for both women and men. The greatest 3D benefit was found for women with less surgical experience. As a possible result of surgical education, this gender specific difference disappears with higher grade of experience. Using a 3D-vision system could facilitate surgical apprenticeship, especially for women.

Combined Therapy with Intravenous Immunoglobulins, Letermovir and (Val-)Ganciclovir in Complicated Courses of CMV-Infection in Transplant Recipients.

The treatment options for cytomegalovirus (CMV) infections in immunosuppressed patients are limited, mainly consisting of (val-)ganciclovir (VGC/GCV) as the first-line treatment. We report on three transplant recipients, one stem cell transplant (allo-HSCT) patient and two kidney transplant (KTx) recipients, with prolonged CMV viremia treated with a combined therapy based on letermovir (LMV), CMV-specific intravenous immunoglobulins (IVIg), and VGC/GCV, which led to the sustained control of CMV viremia in all patients.

Value of spectral detector computed tomography for the early assessment of technique efficacy after microwave ablation of hepatocellular carcinoma.

OBJECTIVES: To investigate whether virtual monoenergetic images (VMI) and iodine maps derived from spectral detector computed tomography (SDCT) improve early assessment of technique efficacy in patients who underwent microwave ablation (MWA) for hepatocellular carcinoma (HCC) in liver cirrhosis. METHODS: This retrospective study comprised 39 patients with 49 HCC lesions treated with MWA. Biphasic SDCT was performed 7.7±4.0 days after ablation. Conventional images (CI), VMI and IM were reconstructed. Signal- and contrast-to-noise ratio (SNR, CNR) in the ablation zone (AZ), hyperemic rim (HR) and liver parenchyma were calculated using regions-of-interest analysis and compared between CI and VMI between 40-100 keV. Iodine concentration and perfusion ratio of HR and residual tumor (RT) were measured. Two readers evaluated subjective contrast of AZ and HR, technique efficacy (complete vs. incomplete ablation) and diagnostic confidence at determining technique efficacy. RESULTS: Attenuation of liver parenchyma, HR and RT, SNR of liver parenchyma and HR, CNR of AZ and HR were significantly higher in low-keV VMI compared to CI (all p<0.05). Iodine concentration and perfusion ratio differed significantly between HR and RT (all p<0.05; e.g. iodine concentration, 1.6±0.5 vs. 2.7±1.3 mg/ml). VMI50keV improved subjective AZ-to-liver contrast, HR-to-liver contrast, visualization of AZ margin and vessels adjacent to AZ compared to CI (all p<0.05). Diagnostic accuracy for detection of incomplete ablation was slightly higher in VMI50keV compared to CI (0.92 vs. 0.89), while diagnostic confidence was significantly higher in VMI50keV (p<0.05). CONCLUSIONS: Spectral detector computed tomography derived low-keV virtual monoenergetic images and iodine maps provide superior early assessment of technique efficacy of MWA in HCC compared to CI.

Protein-loss of SWI/SNF-complex core subunits influences prognosis dependent on histological subtypes of intra- and extrahepatic cholangiocarcinoma.

Cholangiocarcinoma (CCA) is an aggressive malignancy with a 5-year-survival rate of <10%, mainly due to diagnosis in advanced stages and limited therapeutic options in case of progressive disease. Recently, evidence has indicated that alterations in the SWI/SNF-complex (SWI/SNF) may have an important role in the tumorigenesis of CCA. SWI/SNF-related chromatin remodeling has been reported to be crucial for differentiation and tumor suppression, and loss-of-function mutations of SWI/SNF are present in 20% of human malignancies; however, at present, little is known about its relevance in CCA. In the present study, a cohort of 52 patients with the diagnosis of primary CCA was retrospectively collected. All patients underwent surgery with curative intent. Tissue microarray analysis was performed on each tumor for immunohistochemical loss-of-protein analysis of the SWI/SNF core subunits ARID1A, INI-1, BRG1, PBRM-1 and BRM, corresponding to the following CCA subtypes: Extrahepatic CCA (ECCA), small duct or large duct intrahepatic CCA (ICCA). Kaplan-Meier analysis was used to determine survival distribution and survival differences were evaluated by log-rank test. In total, 14 of 52 patients (~35%) exhibited protein-loss of any tested SWI/SNF core subunit. Notably, 17% of patients exhibited a loss of ARID1a; this was the protein loss with the highest frequency. Patients with small and large duct ICCA with protein-loss of any tested SWI/SNF subunit exhibited significantly worse survival compared with the wild-type cohort with proficient protein expression (P=0.013 and P=0.002), whereas no significant survival difference was detected for patients with ECCA. SWI/SNF and its core subunits may be considered promising predictive and therapeutic targets, and require further investigation in patients with CCA.

Monitoring of hepatitis E virus RNA during treatment for chronic hepatitis E virus infection after renal transplantation.

BACKGROUND: Recently, chronic hepatitis E virus (HEV) infections gained increasing attention as a possible cause for elevated liver enzymes of unknown origin and liver cirrhosis in solid organ transplant recipients. Reduction of immunosuppressive therapy and/or use of antiviral drug ribavirin have been established as possible treatment strategies. METHODS: The efficacy of dose reduction of mycophenolic acid (MPA) and ribavirin therapy was retrospectively analyzed in eight renal transplant patients of our outpatient clinic who were diagnosed with HEV infection by detection of specific antibodies (immunoglobulin M and immunoglobulin G) and/or positive RNA in blood and stool. In four patients serial HEV viral loads in blood were measured. RESULTS: Only one patient reached HEV clearance after reduction of immunosuppressive therapy (predominantly reduction of MPA daily dose) alone, whereas six patients were treated with ribavirin after reduction of immunosuppressive therapy due to persistent virus replication. Four of six patients reached HEV clearance after 3 months of ribavirin therapy. HEV clearance was observed after 34-42 days. Two patients, both treated with rituximab within the last 12 months before diagnosis of HEV infection, needed prolonged ribavirin therapy due to persistent viral replication. CONCLUSION: Reduction of daily dose of MPA therapy alone in transplant patients with chronic HEV infection may not be sufficient to control viral replication. HEV clearance under ribavirin therapy shows interindividual variability. Therefore, serial viral monitoring may be useful to personalize treatment duration. Rituximab therapy is a risk factor for complicated-to-treat chronic HEV infection.

Immune Responses to SARS-CoV-2 Infection and Vaccination in Dialysis Patients and Kidney Transplant Recipients.

Dialysis patients and kidney transplant (KTX) recipients suffer from an impaired immune system and show a decreased response to the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) vaccination. We performed a retrospective analysis of 1505 serological SARS-CoV-2 measurements obtained from 887 dialysis patients and 86 KTX recipients. The results were separated by patient subgroups (dialysis/KTX) as well as SARS-CoV-2 status. The latter criterion included SARS-CoV-2-naïve patients with or without COVID-19 vaccination and convalescent patients receiving a booster shot. Serologies of 27 vaccinated healthy individuals served as the reference group. Vaccine-induced cellular immune response was quantified by an interferon-γ release assay in 32 KTX recipients. We determined seroconversion rates of 92.6%, 93.4%, and 71.4% in dialysis patients vaccinated with either BNT162b2, mRNA-1273, or AZD1222, respectively. Vaccination-induced anti-SARS-CoV-2 antibody titers were lower in dialysis patients compared to healthy individuals, and vaccination with mRNA-1273 induced higher titers than BNT162b2. The initial seroconversion rate was 39.5% in KTX recipients vaccinated with BNT162b2. A linear regression model identified medication with mycophenolate-mofetil/mycophenolic acid as an independent risk factor for missing seroconversion. Within a cohort of 32 KTX recipients, cellular and humoral immune reactivity to SARS-CoV-2 was detectable in three patients only. Conclusively, vaccine-induced seroconversion rates were similar in dialysis patients compared to healthy individuals but were strongly impaired in KTX recipients. Anti-SARS-CoV-2 IgG titers elicited by double active immunization were significantly lower in both cohorts compared to healthy individuals, and immune responses to vaccination vanished quickly.