Donor and recipient genetics: Implications for the development of posttransplant diabetes mellitus.

Posttransplant diabetes mellitus (PTDM) is a prevalent complication of liver transplantation and is associated with cardiometabolic complications. We studied the consequences of genetic effects of liver donors and recipients on PTDM outcomes, focusing on the diverse genetic pathways related to insulin that play a role in the development of PTDM. One thousand one hundred fifteen liver transplant recipients without a pretransplant diagnosis of type 2 diabetes mellitus (T2D) and their paired donors recruited from 2 transplant centers had polygenic risk scores (PRS) for T2D, insulin secretion, and insulin sensitivity calculated. Among recipients in the highest T2D-PRS quintile, donor T2D-PRS did not contribute significantly to PTDM. However, in recipients with the lowest T2D genetic risk, donor livers with the highest T2D-PRS contributed to the development of PTDM (OR [95% CI] = 3.79 [1.10-13.1], P = .035). Recipient risk was linked to factors associated with insulin secretion (OR [95% CI] = 0.85 [0.74-0.98], P = .02), while donor livers contributed to PTDM via gene pathways involved in insulin sensitivity (OR [95% CI] = 0.86 [0.75-0.99], P = .03). Recipient and donor PRS independently and collectively serve as predictors of PTDM onset. The genetically influenced biological pathways in recipients primarily pertain to insulin secretion, whereas the genetic makeup of donors exerts an influence on insulin sensitivity.

The Course of LIRADS 3 and 4 Hepatic Abnormalities as Correlated With Explant Pathology: A Single Center Experience.

Background and aims: The Liver Reporting and Data System (LI-RADS) is the standard classification of imaging findings of hepatic abnormalities for hepatocellular carcinoma (HCC) surveillance. We aimed to study the course of LI-RADS 3 and 4 (LR-3 and LR-4) abnormalities through correlations with explant pathology. Methods: A single center retrospective study of liver transplant recipients between January 2016 and September 2019 with HCC on explant pathology was conducted. Eligible patients were divided into three subgroups based on their LI-RADS classification: LR-3/4, LR-5 only, and combination of LR-3/4/5. Results: There were 116 eligible patients with 99 LR-3/4 observations (60 LR-3 and 39 LR-4); the rest had LR-5 lesions. LR-4 more often than LR-3 observations progressed to LR-5 (36% vs 12%) and with shorter duration during follow-up (median 175 days and 196 days). Mean size growth of LR-3 and LR-4 abnormalities were 2.6 and 3.8 mm; median growth rates were 0.2 and 0.4 mm/month, respectively. Numbers of HCC lesions per explant, largest HCC lesion size, and cumulative size were higher in LR-3/4/5 subgroup than LR-5 subgroup (P = 0.007, 0.007 and 0.006, respectively); 68% of LR-3 and 82% of LR-4 abnormalities were confirmed HCC on explant (P = 0.09). Conclusion: Compared to LR-3, more LR-4 abnormalities progressed to LR-5 (12% and 36%, respectively) in a shorter time and with faster growth rate. A high proportion of LR-3 and LR-4 lesions (68% and 82%, respectively) were confirmed HCC on explant, raising the question of whether excluding HCC based on radiologic criteria alone is adequate in those with LR-3/4 abnormalities.

Donor and recipient polygenic risk scores influence the risk of post-transplant diabetes.

Post-transplant diabetes mellitus (PTDM) reduces allograft and recipient life span. Polygenic risk scores (PRSs) show robust association with greater risk of developing type 2 diabetes (T2D). We examined the association of PTDM with T2D PRS in liver recipients (n = 1,581) and their donors (n = 1,555), and kidney recipients (n = 2,062) and their donors (n = 533). Recipient T2D PRS was associated with pre-transplant T2D and the development of PTDM. T2D PRS in liver donors, but not in kidney donors, was an independent risk factor for PTDM development. The inclusion of a combined liver donor and recipient T2D PRS significantly improved PTDM prediction compared with a model that included only clinical characteristics: the area under the curve (AUC) was 67.6% (95% confidence interval (CI) 64.1-71.1%) for the combined T2D PRS versus 62.3% (95% CI 58.8-65.8%) for the clinical characteristics model (P = 0.0001). Liver recipients in the highest quintile of combined donor and recipient T2D PRS had the greatest risk of PTDM, with an odds ratio of 3.22 (95% CI 2.07-5.00) (P = 1.92 × 10-7) compared with those in the lowest quintile. In conclusion, T2D PRS identifies transplant candidates with high risk of PTDM for which pre-emptive diabetes management and donor selection may be warranted.

Incidence of acute rejection and patient survival in combined heart-liver transplantation.

Combined heart-liver transplantation (CHLT) is indicated for patients with concomitant end-stage heart and liver disease or patients with amyloid heart disease where liver transplantation mitigates progression. Limited data suggest that the liver allograft provides immunoprotection for heart and kidney allografts in combined transplantation from the same donor. We hypothesized that CHLT reduces the incidence of acute cellular rejection (ACR) and the development of de novo donor-specific antibodies (DSAs) compared with heart-alone transplantation (HA). We conducted a retrospective analysis of 32 CHLT and 280 HA recipients in a single-center experience. The primary outcome was incidence of ACR based on protocol and for-cause myocardial biopsy. Rejection was graded by the International Society of Heart and Lung Transplantation guidelines with Grade 2R and higher considered significant. Secondary outcomes included the development of new DSAs, cardiac function, and patient and cardiac graft survival rates. Of CHLT patients, 9.7% had ACR compared with 45.3% of HA patients (p < 0.01). Mean pretransplant calculated panel reactive antibody (cPRA) levels were similar between groups (CHLT 9.4% vs. HA 9.5%; p = 0.97). Among patients who underwent testing, 26.9% of the CHLT and 16.7% of HA developed DSA (p = 0.19). Despite the difference in ACR, patient and cardiac graft survival rates were similar at 5 years (CHLT 82.1% vs. HA 80.9% [p = 0.73]; CHLT 82.1% vs. HA 80.9% [p = 0.73]). CHLT reduced the incidence of ACR in the cardiac allograft, suggesting that the liver offers immunoprotection against cellular mechanisms of rejection without significant impacts on patient and cardiac graft survival rates. CHLT did not reduce the incidence of de novo DSA, possibly portending similar long-term survival among cardiac allografts in CHLT and HA.

Whole transcriptome profiling of prospective endomyocardial biopsies reveals prognostic and diagnostic signatures of cardiac allograft rejection.

BACKGROUND: Heart transplantation provides a significant improvement in survival and quality of life for patients with end-stage heart disease, however many recipients experience different levels of graft rejection that can be associated with significant morbidities and mortality. Current clinical standard-of-care for the evaluation of heart transplant acute rejection (AR) consists of routine endomyocardial biopsy (EMB) followed by visual assessment by histopathology for immune infiltration and cardiomyocyte damage. We assessed whether the sensitivity and/or specificity of this process could be improved upon by adding RNA sequencing (RNA-seq) of EMBs coupled with histopathological interpretation. METHODS: Up to 6 standard-of-care, or for-cause EMBs, were collected from 26 heart transplant recipients from the prospective observational Clinical Trials of Transplantation (CTOT)-03 study, during the first 12-months post-transplant and subjected to RNA-seq (n = 125 EMBs total). Differential expression and random-forest-based machine learning were applied to develop signatures for classification and prognostication. RESULTS: Leveraging the unique longitudinal nature of this study, we show that transcriptional hallmarks for significant rejection events occur months before the actual event and are not visible using traditional histopathology. Using this information, we identified a prognostic signature for 0R/1R biopsies that with 90% accuracy can predict whether the next biopsy will be 2R/3R. CONCLUSIONS: RNA-seq-based molecular characterization of EMBs shows significant promise for the early detection of cardiac allograft rejection.

Impact of Donor and Recipient Clinical Characteristics and Hepatic Histology on Steatosis/Fibrosis Following Liver Transplantation.

BACKGROUND: Deceased donor and recipient predictors of posttransplant steatosis/steatohepatitis and fibrosis are not well known. Our aim was to evaluate the prevalence and assess donor and recipient predictors of steatosis, steatohepatitis, and fibrosis in liver transplantation recipients. METHODS: Using the immune tolerance network A-WISH multicenter study (NCT00135694), donor and recipient demographic and clinical features were collected. Liver biopsies were taken from the donor liver at transplant, and from recipients per protocol and for-cause (ie, abnormal transaminases and to rule out rejection) and were interpreted by a central pathologist. RESULTS: One hundred eighty-three paired donor/recipients liver biopsies at the time of transplant and posttransplant follow-up (median time 582 d; average time to last biopsies was 704 d [SD ± 402 d]) were analyzed. Donor steatosis did not influence recipient steatosis or fibrosis. Ten of 183 recipients had steatohepatitis on the last biopsy. Recipient body mass index at the time of liver biopsy was the most influential factor associated with posttransplant steatosis. Both donor and recipient metabolic syndrome features were not associated with graft steatosis. Untreated hepatitis C viral (HCV) infection was the most influential factor associated with the development of allograft fibrosis. CONCLUSIONS: In a large experience evaluating paired donor and recipient characteristics, recipient body mass index at the time of liver biopsy was most significantly associated with posttransplant steatosis. Untreated HCV etiology influenced graft fibrosis. Thus relative to untreated HCV, hepatic fibrosis in those with steatosis/steatohepatitis is less common though long-term follow-up is needed to determine the course of posttransplant fibrosis. Emphasis on recipient weight control is essential.

Functional Characterization of Organoids Derived From Irreversibly Damaged Liver of Patients With NASH.

BACKGROUND AND AIMS: NASH will soon become the leading cause of liver transplantation in the United States and is also associated with increased COVID-19 mortality. Currently, there are no Food and Drug Administration-approved drugs available that slow NASH progression or address NASH liver involvement in COVID-19. Because animal models cannot fully recapitulate human NASH, we hypothesized that stem cells isolated directly from end-stage liver from patients with NASH may address current knowledge gaps in human NASH pathology. APPROACH AND RESULTS: We devised methods that allow the derivation, proliferation, hepatic differentiation, and extensive characterization of bipotent ductal organoids from irreversibly damaged liver from patients with NASH. The transcriptomes of organoids derived from NASH liver, but not healthy liver, show significant up-regulation of proinflammatory and cytochrome p450-related pathways, as well as of known liver fibrosis and tumor markers, with the degree of up-regulation being patient-specific. Functionally, NASH liver organoids exhibit reduced passaging/growth capacity and hallmarks of NASH liver, including decreased albumin production, increased free fatty acid-induced lipid accumulation, increased sensitivity to apoptotic stimuli, and increased cytochrome P450 metabolism. After hepatic differentiation, NASH liver organoids exhibit reduced ability to dedifferentiate back to the biliary state, consistent with the known reduced regenerative ability of NASH livers. Intriguingly, NASH liver organoids also show strongly increased permissiveness to severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) vesicular stomatitis pseudovirus as well as up-regulation of ubiquitin D, a known inhibitor of the antiviral interferon host response. CONCLUSION: Expansion of primary liver stem cells/organoids derived directly from irreversibly damaged liver from patients with NASH opens up experimental avenues for personalized disease modeling and drug development that has the potential to slow human NASH progression and to counteract NASH-related SARS-CoV-2 effects.

Occult Hepatocellular Carcinoma Associated With Transjugular Intrahepatic Portosystemic Shunts in Liver Transplant Recipients.

Transplant eligibility for hepatocellular carcinoma (HCC) is determined by the imaging identification of tumor burden within the Milan criteria. Transjugular intrahepatic portosystemic shunt(s) (TIPS) reduce portal hypertension but may impact HCC visualization. It was hypothesized that the presence of pretransplant TIPS would correlate with occult HCC and reduced survival. A single-center, retrospective, case control study was performed among liver transplant recipients with HCC (2000-2017). The primary endpoint was occult disease on explant pathology. Backward stepwise logistic regression was performed. The secondary endpoints disease-free survival (DFS) and overall survival (OS) were evaluated with Kaplan-Meier curves and Cox regression analysis. Of 640 patients, 40 had TIPS and more frequently exhibited occult disease (80.0% versus 43.1%; P < 0.001; odds ratio [OR], 4.16; P < 0.001). Portal vein thrombosis (PVT) similarly correlated with occult disease (OR, 1.97; P = 0.02). Explant tumor burden was equivalent between TIPS subgroups; accordingly, TIPS status was not independently associated with reduced DFS or OS. However, exceeding the Milan criteria was associated with reduced DFS (hazard ratio, 3.21; P = 0.001), and TIPS status in patients with a single suspected lesion (n = 316) independently correlated with explant tumor burdens beyond these criteria (OR, 13.47; P = 0.001). TIPS on pretransplant imaging are associated with occult HCC on explant pathology. Comparable occult disease findings in patients with PVT suggest that the mechanism may involve altered hepatic perfusion, obscuring imaging diagnosis. TIPS are not independently associated with reduced DFS or OS but are associated with exceeding the Milan criteria for patients with a single suspected lesion. The presence of TIPS may necessitate a higher index of suspicion for occult HCC.

Successful transatlantic bilateral hand transplant in a young female highly sensitized to HLA class II antigens.

Vascularized composite allografts may be more susceptible to rejection than other types of organ transplants, particularly in sensitized recipients. We describe a successful transatlantic bilateral hand transplant in a 40-year old woman who was highly sensitized to class II HLA antigens including HLA-DPB1 (UNet CPRA = 86%). Prior to transplantation, we selected an upper limb donor based on HLA class II matching and absence of donor specific antibodies, given evidence that class II mismatches are associated with acute cellular rejection in hand transplants. The patient was conditioned using five doses of thymoglobulin, and her immunosuppression included tacrolimus, rapamycin, mycophenolate, and prednisone. Post-transplant, the patient non-DSA anti-HLA antibody levels drastically increased, but only transiently and weak DSAs developed, which became undetectable by two months posttransplant. Following transplantation, periodic biopsies over 6 months indicated no evidence of rejection except for transient Banff grade 1 and one sample with grade 2 acute rejection. There was no evidence of rejection on her recent 1-year follow-up. The patient is currently healthy, has recovered protective sensibility, and is regaining excellent function. This case highlights the importance of pre-transplantation planning, donor selection/compatibility, and ethical considerations in the ultimate success of VCA.

Predictors, Presentation, and Treatment Outcomes of Recurrent Hepatocellular Carcinoma After Liver Transplantation: A Large Single Center Experience.

BACKGROUND: Liver transplantation (LT) is an accepted therapeutic option for hepatocellular carcinoma (HCC) in patients with cirrhosis. Despite careful candidate selection, HCC recurrence occurs. We aimed to describe the predictors of recurrence, clinical presentation, and predictors of survival after HCC recurrence post-LT. METHODS: Patients with recurrent HCC after LT between January 1996 and December 2017 were retrospectively reviewed. RESULTS: Of 711 patients, 96 (13.5%) patients had post-LT HCC recurrence. The median time to recurrence was 17.1 months, and the median survival was 10.1 months. Initial recurrence was more often in the graft (34.4%), and most (60.4%) had multiple recurrent lesions, and 26% were in multiple sites. In multivariate analysis, factors associated with shorter survival were poorly differentiated histology in explant (Hazard ratio [HR] = 1.96; p = 0.027), bilirubin ≥1.2 mg/dL (HR = 2.47; p = 0.025), and albumin <3.5 mg/dL (HR = 2.13; p = 0.014) at recurrence, alpha-fetoprotein at recurrence ≥ 1000 ng/mL (HR = 2.96; p = 0.005), and peritoneal disease (HR = 3.20; p = 0.022). There was an increased survival in patients exposed to sirolimus (HR = 0.32; p < 0.0001). CONCLUSIONS: Recurrent HCC after LT is often in extrahepatic sites with a decreased survival in those with poorly differentiated explant pathology, high bilirubin, low albumin, marked elevation of alpha-fetoprotein at recurrence, and peritoneal recurrence. Sirolimus-based immunosuppression may provide benefit.

Deletion of donor-reactive T cell clones after human liver transplant.

We recently developed a high throughput T cell receptor ß chain (TCRß) sequencing-based approach to identifying and tracking donor-reactive T cells. To address the role of clonal deletion in liver allograft tolerance, we applied this method in samples from a recent randomized study, ITN030ST, in which immunosuppression withdrawal was attempted within 2 years of liver transplantation. We identified donor-reactive T cell clones via TCRß sequencing following a pre-transplant mixed lymphocyte reaction and tracked these clones in the circulation following transplantation in 3 tolerant and 5 non-tolerant subjects. All subjects showed a downward trend and significant reductions in donor-reactive TCRß sequences were detected post-transplant in 6 of 8 subjects, including 2 tolerant and 4 non-tolerant recipients. Reductions in donor-reactive TCRß sequences were greater than those of all other TCRß sequences, including 3rd party-reactive sequences, in all 8 subjects, demonstrating an impact of the liver allograft after accounting for repertoire turnover. Although limited by patient number and heterogeneity, our results suggest that partial deletion of donor-reactive T cell clones may be a consequence of liver transplantation and does not correlate with success or failure of early immunosuppression withdrawal. These observations underscore the organ- and/or protocol-specific nature of tolerance mechanisms in humans.

Analysis of Outcomes in Living Donor Liver Transplants Involving Reconstructive Microsurgeons.

BACKGROUND: Living donor transplantation is becoming increasingly popular as a modality for patients necessitating liver transplantation. Hepatic artery thrombosis (HAT) remains the most feared acute postoperative complication associated with living-donor liver transplantation. Preoperative planning, including scheduling reconstructive microsurgeons to perform the hepatic artery anastomosis using a surgical microscope or loupes, can decrease HAT rates. METHODS: A retrospective review of two reconstructive microsurgeons at a single institution was performed to analyze postoperative outcomes of adult and pediatric live donor liver transplants where reconstructive microsurgeons performed the hepatic artery anastomosis. One surgeon utilized the surgical microscope, while the other surgeon opted to use surgical loupes for the anastomosis. RESULTS: A total of 38 patients (30 adult and eight pediatric) met inclusion criteria for this study, and average patient age in the adult and pediatric population studied was 48.5 and 3.6 years, respectively. Etiologies of adult patients' liver failure were most commonly cholestatic (43%), followed by alcohol (23%), hepatitis C virus-related cirrhosis (17%), and nonalcoholic steatohepatitis (7%), while etiologies of pediatric liver failure were most commonly cholestatic (62.5%). None of the patients (0%) experienced acute postoperative HAT. On average, 22 and 25 months of postoperative follow-up was obtained for the adult and pediatric cohorts, respectively, and only one adult patient was found to have any liver-related complication. CONCLUSION: A collaborative relationship between reconstructive microsurgeons and transplant surgeons mitigates the risk of HAT and improves patient outcomes in living donor liver transplantation.

Genetic and Epigenetic Fine Mapping of Complex Trait Associated Loci in the Human Liver.

Deciphering the impact of genetic variation on gene regulation is fundamental to understanding common, complex human diseases. Although histone modifications are important markers of gene regulatory elements of the genome, any specific histone modification has not been assayed in more than a few individuals in the human liver. As a result, the effects of genetic variation on histone modification states in the liver are poorly understood. Here, we generate the most comprehensive genome-wide dataset of two epigenetic marks, H3K4me3 and H3K27ac, and annotate thousands of putative regulatory elements in the human liver. We integrate these findings with genome-wide gene expression data collected from the same human liver tissues and high-resolution promoter-focused chromatin interaction maps collected from human liver-derived HepG2 cells. We demonstrate widespread functional consequences of natural genetic variation on putative regulatory element activity and gene expression levels. Leveraging these extensive datasets, we fine-map a total of 74 GWAS loci that have been associated with at least one complex phenotype. Our results reveal a repertoire of genes and regulatory mechanisms governing complex disease development and further the basic understanding of genetic and epigenetic regulation of gene expression in the human liver tissue.

Pediatric vascularized composite allotransplantation: What is the landscape for obtaining appropriate donors in the United States?

Listing the world's first pediatric bilateral hand transplant patient for a donor posed many challenges including matching the appropriate donor age, bone size, skin tone, and growth potential in an already limited donor population. This study describes the prevalence and distribution of potential pediatric VCA donors in the United States. We assessed the UNOS database from 2008 to 2015 to identify the prevalence of potential pediatric VCA donors. Standard VCA inclusion and exclusion criteria were applied to the dataset for all pediatric solid organ donors. Frequency analyses were performed of characteristics important for VCA matching. The dataset began with 57 300 brain-dead donors and after applying the inclusion and exclusion criteria including age <18, decreased to 4663 (8.1%). The number of pediatric potential VCA donors per UNOS region ranged from 11 to 112/year. The majority of pediatric potential VCA donors were blood type O Whites, with the least common profile being blood type AB of "other" ethnicity. The present study confirmed that pediatric VCA donors are rare and may require longer travel times for procurement and listing at multiple centers in order to find a suitable donor. This will be a limiting factor for the expansion of pediatric VCA.

Hepatocytes direct the formation of a pro-metastatic niche in the liver.

The liver is the most common site of metastatic disease1. Although this metastatic tropism may reflect the mechanical trapping of circulating tumour cells, liver metastasis is also dependent, at least in part, on the formation of a 'pro-metastatic' niche that supports the spread of tumour cells to the liver2,3. The mechanisms that direct the formation of this niche are poorly understood. Here we show that hepatocytes coordinate myeloid cell accumulation and fibrosis within the liver and, in doing so, increase the susceptibility of the liver to metastatic seeding and outgrowth. During early pancreatic tumorigenesis in mice, hepatocytes show activation of signal transducer and activator of transcription 3 (STAT3) signalling and increased production of serum amyloid A1 and A2 (referred to collectively as SAA). Overexpression of SAA by hepatocytes also occurs in patients with pancreatic and colorectal cancers that have metastasized to the liver, and many patients with locally advanced and metastatic disease show increases in circulating SAA. Activation of STAT3 in hepatocytes and the subsequent production of SAA depend on the release of interleukin 6 (IL-6) into the circulation by non-malignant cells. Genetic ablation or blockade of components of IL-6-STAT3-SAA signalling prevents the establishment of a pro-metastatic niche and inhibits liver metastasis. Our data identify an intercellular network underpinned by hepatocytes that forms the basis of a pro-metastatic niche in the liver, and identify new therapeutic targets.

Outcomes of Living-donor Liver Transplantation Using Grafts Heterozygous for α-1 Antitrypsin Gene Mutations.

BACKGROUND: Patients heterozygous for an abnormal α-1 antitrypsin (A1AT) mutation may have an increased risk of liver disease in the setting of a secondary contributing factor. METHODS: This single-center retrospective cohort study compared donor and recipient outcomes of A1AT heterozygous versus normal phenotype adult living-donor liver transplants (LDLTs). RESULTS: Between 2010 and 2016, 11 A1AT heterozygous donors and 10 recipients were compared to 57 normal donors and 41 recipients. There were no significant differences in sex, age, or race/ethnicity by A1AT phenotype. Heterozygous donors had significantly lower serum A1AT (median 100 mg/dL versus 131 mg/dL; P < 0.001). Median liver volume at 3 months post-LDLT was not different among donors or their recipients (1164 mm in heterozygous versus 1257 mm in normal [P = 0.449] for donors; 1563 mm versus 1606 mm [P = 0.387], respectively, for recipients). Recipient serum alkaline phosphatase at 1 month and 1 year post-LDLT was significantly higher in recipients of A1AT heterozygous grafts (160 U/L versus 99.5 U/L; P = 0.025 at 1 mo) but did not persist at 2 years. In addition, there was no association between A1AT level and liver volume at 3 months posttransplant in donors or recipients. CONCLUSIONS: Patients with a heterozygous A1AT mutation should be considered for living-liver donation.

Prevalence and Impact of De Novo Donor-Specific Antibodies During a Multicenter Immunosuppression Withdrawal Trial in Adult Liver Transplant Recipients.

The development of human leukocyte antigen (HLA) donor-specific antibody/antibodies (DSA) is not well described in liver transplant (LT) patients undergoing immunosuppression (IS) withdrawal protocols despite the allograft risk associated with de novo DSA (dnDSA). We analyzed the development of dnDSA in 69 LT patients who received calcineurin inhibitor monotherapy and were enrolled in the ITN030ST study. Of these 69 patients, 40 stable patients were randomized to IS maintenance (n = 9) or IS minimization (n = 31). Nine of the 31 IS minimization patients achieved complete withdrawal and were free of IS. Among patients who achieved stable IS monotherapy 1 year after transplantation, the prevalence of dnDSA was 18.8%. Acute rejections and the biopsy-proven findings disqualifying patients from IS withdrawal attempt were factors associated with dnDSA development (P = 0.011 and P = 0.041, respectively). Among randomized patients, dnDSA prevalence was 51.7% after IS minimization and 66.7% in IS-free patients. dnDSA prevalence in patients on IS maintenance was 44.4%. dnDSA development during IS minimization was a risk factor for acute rejection (P = 0.015). The majority of dnDSA were against HLA-DQ antigens (78.7%). Conclusion. During the first year following transplantation, acute rejections increase the risk of developing dnDSA, so dnDSA positivity should be considered for IS withdrawal eligibility; during IS minimization, dnDSA development was associated with acute rejection, which prevented further IS withdrawal attempts.