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Objective: Adrenocortical carcinoma is a rare condition, with limited comprehensive reports from Japan. This study aimed to review Japan's data on adrenocortical carcinoma by assessing information from 46 patients—with adrenocortical carcinoma across 10 Japanese university hospitals. Methods: We conducted a retrospective multi‐institutional analysis of the clinical characteristics of adrenocortical carcinoma in Japan. We evaluated data from 46 patients across 10 university hospitals over 10 years and analyzed the relationship between clinicopathological characteristics and overall survival. Results: Five‐ and 10‐year overall survival rates were 59% and 53%, respectively. Overall survival was significantly different among the tumor–node–metastasis system for adrenocortical carcinoma of the American Joint Committee on Cancer/International Union Against Cancer, with the worst prognosis in stage IV (p = 0.0044). In our cohort, neither the Weiss score nor the Ki‐67 proliferation index correlated with overall survival. Adjuvant treatment did not yield improved overall survival, whereas resection of the primary tumor in stage IV disease was significantly associated with improved overall survival (p = 0.0262). Out of the cases evaluated for plasma hormones, plasma cortisol, aldosterone, testosterone, and DHEA‐S levels were measured at 23%, 42%, 29%, and 62%, respectively, demonstrating higher levels than the upper normal limits. Conclusion: Patients with stage IV adrenocortical carcinoma had a poor prognosis; however, resection of the primary tumor in stage IV disease was associated with prolonged survival. The results of this study are expected to contribute to future treatment of adrenocortical carcinoma in Japan. [ABSTRACT FROM AUTHOR]

Objectives: When primary treatment has been inadequate, nivolumab and axitinib are often used as a secondary treatments for patients with metastatic renal cell carcinoma (mRCC). However, there have been few reports comparing the efficacy and safety of these drugs. Methods: We retrospectively investigated 58 patients treated with nivolumab and 57 patients treated with axitinib as secondary treatment between April 2013 and December 2019. We then assessed the clinical efficacy and safety of the treatments in both groups. Results: The most common primary therapy was sunitinib (61.7%). Both nivolumab and axitinib groups showed no significant differences in terms of the objective response rate and disease control rate (p = 0.280 and p = 0.518, respectively). Importantly, progression‐free survival (PFS) and overall survival (OS) seemed to be similar in patients treated with nivolumab and axitinib (p = 0.527 and p = 0.266, respectively), irrespective of the objective response to primary therapy. Furthermore, a Cox proportional hazards model showed that pretreatment Karnofsky Performance Status was significantly associated with PFS and OS. Although the incidence of adverse events was significantly higher in the patients treated with axitinib, there was no significant difference in time to treatment failure between the two groups. Conclusions: Nivolumab and axitinib showed similar clinical benefits as secondary treatment in patients with mRCC; thus, they should be an option in sequential therapy following treatment with tyrosine kinase inhibitors (TKIs). Future studies and feasible therapeutic biomarkers would help predict the clinical response to TKIs or immune checkpoint inhibitors in patients with mRCC. [ABSTRACT FROM AUTHOR]

Background: In metastatic renal-cell carcinoma (mRCC), recent clinical trials have shown efficacy of first-line combination therapy, as evidenced by better clinical outcome over target therapy. However, there are insufficient real-world evidences in mRCC patients in Japan. Methods: We performed a multicenter retrospective study of 72 mRCC patients who received nivolumab plus ipilimumab as first-line treatment between September 2018 and July 2021. Patient's characteristics, clinical outcomes and safety were retrospectively reviewed. We analyzed overall response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS) in patients treated with combination therapy. Results: Of all patients, the median age was 70 years (range, 36–86) and the major type of histology was clear cell RCC (n = 55; 76.4%). Progressive disease (n = 25; 34.8%) and irAEs (n = 22; 30.6%) were the most common causes for discontinuing treatment. Median PFS and OS seemed similar between patients who discontinued treatment because of irAEs and for patients who did not (p = 0.360 and p = 0.069, respectively). Importantly, for patients with synchronous metastatic disease at diagnosis (n = 56), nephrectomy before initiating nivolumab plus ipilimumab had a significantly positive impact on better OS when compared to that in patients without nephrectomy (p = 0.028). Conclusion: This study confirms efficacy and safety of nivolumab plus ipilimumab for mRCC patients in real-world settings. Furthermore, nivolumab plus ipilimumab was associated with a better outcome in patients who had undergone nephrectomy at diagnosis for synchronous mRCC. [ABSTRACT FROM AUTHOR]

Objectives: Post‐transplant lymphoproliferative disorder is a potentially life‐threatening complication that has a greater risk of occurrence in the setting of immunosuppression and oncogenic viral infections after transplant surgery. Few studies have reported the cumulative incidence, histological subtypes and clinical outcomes of this disorder in kidney transplant recipients. Methods: We retrospectively investigated 34 post‐transplant lymphoproliferative disorder patients diagnosed out of the 1210 kidney transplant recipients who had undergone the surgery at the two largest centers in Japan between January 1983 and December 2017. Results: A total of 32 patients (94.1%) developed late‐onset post‐transplant lymphoproliferative disorder (diagnosed 1 year after transplantation). The cumulative incidence rates were 0.76% and 1.59% at 5 and 10 years post‐transplantation, respectively. The central nervous system was the most common site (35.3%, 12/34). Overall survival was similar between patients with and without central nervous system lesions (P = 0.676). Of all of the cases, 23.5% (8/34) were detected through cancer screening. Importantly, patients with screening‐detected post‐transplant lymphoproliferative disorder had better overall survival than those with the disorder who had been symptom detected (P = 0.0215). Overall survival was significantly reduced in patients who developed the disorder compared with those who did not (P = 0.0001). Conclusions: Post‐transplant lymphoproliferative disorder was more likely to occur in the late post‐transplantation period, which showed that long‐term medical examination for transplant recipients is required. Based on our findings, we propose vigilant, long‐term, cancer screening in kidney transplant recipients. [ABSTRACT FROM AUTHOR]

Kidney transplantation is the most promising treatment to improve mortality and life quality in end‐stage kidney disease; however, cancer remains a leading cause of death. Several factors including immunosuppressants might be associated with a gradual increase in cumulative cancer incidence after kidney transplantation. Risk factors for cancer and overall and cancer‐specific survival were analyzed in 1973 kidney transplant recipients from three study institutions in Japan. The 5‐, 10‐, 20‐, and 30‐year overall and cancer‐specific survival rates were 93.3%, 88.4%, 78.0%, and 63.6% and 99.4%, 98.0%, 95.3%, and 91.7%, respectively. The overall survival rate was significantly higher and the graft survival rate was significantly lower in recipients without cancer than in those with cancer. Older recipient age, longer dialysis duration before kidney transplantation, and history of transfusion were significant predictors of cancer. Dialysis duration before kidney transplantation was a prognostic factor of overall survival rate. Regarding cancer‐specific survival rates, older recipient age and dialysis duration before kidney transplantation were prognostic factors of worse cancer‐specific survival rates. The type of immunosuppressant was not associated with an increased cancer rate. Aggressiveness of immunosuppressant regimens or potent immunosuppressants might improve graft survival rate while inducing de novo cancer after kidney transplantation. Older age and longer dialysis duration before kidney transplantation were risk factors of cancer‐specific survival rate. [ABSTRACT FROM AUTHOR]

Total ischemic time (TIT) potentially affects graft survival in organ transplantation. However, in simultaneous pancreas-kidney (SPK) transplantation, the impact of TIT of the pancreas (P-TIT) and kidney graft (K-TIT) on posttransplant outcomes remains unclear. This study investigated the impact of P-TIT and K-TIT on postoperative outcomes in patients after SPK at our institution in Japan. This study included 52 patients who underwent SPK at our hospital from April 2000 to March 2022. Of this patient group, the 52 patients were divided into a short P-TIT group (n = 25), long P-TIT group (n = 27), short K-TIT group (n = 42), and long K-TIT group (n = 10). Short- and long-term postoperative outcomes were compared between the groups. The long K-TIT group had a significantly higher rate of patients who did not urinate intraoperatively (50% vs 7%; P =. 0007) and those requiring postoperative hemodialysis (80% vs 38%; P =.0169), as well as a significant longer duration of postoperative hemodialysis (97 ± 147 days vs 6 ± 9 days; P =.0016). These were not significantly different between the short and long P-TIT groups. Kidney or pancreas graft survival was not significantly different between the short and long P-TIT or K-TIT groups. Patients with prolonged K-TIT during SPK exhibited poor short-term outcomes, but no significant influence of K-TIT was identified on long-term outcomes. The P-TIT did not affect any significant outcomes. These results indicate that shortening K-TIT may improve short-term outcomes after SPK. [ABSTRACT FROM AUTHOR]

Introduction: Functional decline occurs during dialysis initiation, particularly in unplanned cases. To prevent unplanned hemodialysis, we aimed to identify associated factors from the first referral to the nephrology department to hemodialysis initiation and assess patient prognosis post-unplanned hemodialysis initiation., Methods: This retrospective study involved 257 Japanese patients initiating hemodialysis and compared patient characteristics based on whether hemodialysis was planned or unplanned at a single center. Patient outcomes were evaluated in collaboration with maintenance hemodialysis centers., Results: Unplanned hemodialysis initiation correlated with heart failure history (p < 0.05) and infections like pneumonia (p < 0.001). Patients with unplanned hemodialysis initiation had a worse prognosis than those with planned initiation (p < 0.001), and multivariable Cox regression showed it as an independent risk factor for death (p < 0.05)., Conclusions: Hygiene and careful attention to heart failure may reduce unplanned hemodialysis and improve patient well-being and healthcare efficiency. This retrospective analysis highlights crucial considerations for optimizing the initiation of hemodialysis., (© 2024 International Society for Apheresis and Japanese Society for Apheresis.)

Background: Letermovir is approved for cytomegalovirus (CMV) prophylaxis in adult allogeneic hematopoietic cell transplantation recipients worldwide and is also approved in the United States for CMV prophylaxis in adult high-risk (D+/R-) kidney transplant recipients (KTRs). The safety and efficacy of letermovir for CMV prophylaxis in adult Japanese KTRs are reported here., Methods: In this Phase 3, single-arm, open-label study, adult Japanese KTRs with CMV serostatuses D+/R-, D+/R+, and D-/R+ received letermovir 480 mg daily orally within 7 days post-transplant through Week 28. Participants were followed through Week 52. The primary objective was to evaluate letermovir safety and tolerability. Efficacy was a secondary objective, measured by CMV disease, CMV disease or infection requiring intervention, and quantifiable CMV DNAemia. All CMV disease cases were confirmed by an independent adjudication committee., Results: Among 22 participants (12 were D+/R-) who received letermovir prophylaxis, 20 (90.9%) experienced ≥ 1 AE through Week 28. Most AEs were mild to moderate in severity; no deaths were reported. During the prophylaxis period through Week 28, one transient case of quantifiable CMV DNAemia was detected, but no CMV disease or infection requiring intervention was reported. Through Week 52, four D+/R- participants met the endpoint of CMV disease or infection requiring intervention, of whom two had committee-confirmed CMV syndrome; all recovered with CMV therapy. A total of 5 participants had quantifiable CMV DNAemia through Week 52., Conclusion: Letermovir was generally well tolerated, and the data support its use for the prevention of CMV disease/infection in adult Japanese KTRs., Trial Registration: ClinicalTrials.gov NCT04129398., (© 2024. Merck & Co., Inc., Rahway, NJ, USA and its affiliates, Hideki Ishida, Norihiko Goto, Ryoichi Imamura, Hajime Sasaki, Kohei Unagami, Kenta Futamura 2024.)

The coronavirus disease-19 (COVID-19) vaccine efficacy and immunogenicity in the immunocompetent population are well established. However, in solid organ transplant (SOT) recipients, because of their use of immunosuppressive medication, the immunogenicity of these severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines remains suboptimal. Both BNT162b2 and mRNA1273 have been used for some time, but their immunogenicity has not been directly compared in this immunocompromised patient group. We performed a post-hoc analysis of a previous prospective cohort study. The inclusion criteria were adult SOT recipients with active grafts at least 1 month after SOT. After giving consent, participants chose to receive either BNT162b2 or mRNA1273 vaccine. Anti-spike-protein-S antibody against SARS-CoV-2 was measured. Propensity scores were calculated via logistic regression to transform the probability of having received either BNT162b2 or mRNA1273 vaccine, and a model was developed. We enrolled 623 SOT recipients. In the propensity score-matched analysis, 100 recipients were selected for BNT162b2 and 100 for mRNA1273. SARS-CoV-2 anti-spike protein antibody positivity with BNT162b2 versus mRNA1273 at 3 weeks after the first dose, 1 month after the second dose, 3 months after the second dose, and 6 months after the second dose were 10% versus 19% (P = .07), 51% versus 58% (P = .30), 74% versus 88% (P = .01), and 78% versus 87% (P = .13), respectively. We conducted a propensity score-matched comparison of BNT162b2 and mRNA1273 vaccines as the primary series of COVID-19 vaccines in SOT recipients. We found significantly better immunogenicity with the mRNA1273 vaccine than with BNT162b2., (© 2023 The Scandinavian Foundation for Immunology.)

Background: Non-invasive, prompt, and proper detection tools for kidney graft injuries (KGIs) are awaited to ensure graft longevity. We screened diagnostic biomarkers for KGIs following kidney transplantation using extracellular vesicles (EVs; exosomes and microvesicles) from the urine samples of patients., Methods: One hundred and twenty-seven kidney recipients at 11 Japanese institutions were enrolled in this study; urine samples were obtained prior to protocol/episode biopsies. EVs were isolated from urine samples, and EV RNA markers were assayed using quantitative reverse transcription polymerase chain reaction. Diagnostic performance of EV RNA markers and diagnostic formulas comprising these markers were evaluated by comparison with the corresponding pathological diagnoses., Results: EV CXCL9, CXCL10, and UMOD were elevated in T-cell-mediated rejection samples compared with other KGI samples, while SPNS2 was elevated in chronic antibody-mediated rejection (cABMR) samples. A diagnostic formula developed through Sparse Logistic Regression analysis using EV RNA markers allowed us to accurately (with an area under the receiver operator characteristic curve [AUC] of 0.875) distinguish cABMR from other KGI samples. EV B4GALT1 and SPNS2 were also elevated in cABMR, and a diagnostic formula using these markers was able to distinguish between cABMR and chronic calcineurin toxicity accurately (AUC 0.886). In interstitial fibrosis and tubular atrophy (IFTA) urine samples and those with high Banff chronicity score sums (BChS), POTEM levels may reflect disease severity, and diagnostic formulas using POTEM detected IFTA (AUC 0.830) and high BChS (AUC 0.850)., Conclusions: KGIs could be diagnosed with urinary EV mRNA analysis with relatively high accuracy., (© 2023. The Author(s).)

Background: Recently, chronic hepatitis E has been reported in solid organ transplant (SOT) recipients in European countries. Previously, we clarified the prevalence of hepatitis E virus (HEV) infection in Japanese liver transplant recipients and identified 2 chronic hepatitis E patients infected by blood transfusion. However, the rate of HEV infection in recipients of SOTs other than liver in Japan remains unclear, so we conducted a nationwide survey to clarify the prevalence of chronic HEV infection in Japanese heart and kidney transplant recipients., Methods: A total of 99 heart and 2526 kidney transplant recipients in 17 hospitals in Japan were examined for the presence of the IgG class of anti-HEV antibodies as well as for serum HEV RNA., Results: The prevalence of anti-HEV IgG among heart and kidney transplant recipients was 7.07% (7/99) and 4.08% (103/2526), respectively. One heart transplant patient (1.01%) and 11 kidney transplant patients (0.44%) were found to be positive for HEV RNA. The HEV isolates from all viremic patients were typed as genotype 3. Four patients developed chronic hepatitis E after transplantation. Three patients were treated with ribavirin; their liver enzymes normalized, and HEV RNA became negative immediately. Sustained virologic response was achieved in all cases., Conclusions: This is the first nationwide survey of HEV infection in Japanese heart and kidney transplant recipients. The prevalence of anti-HEV IgG and HEV RNA in heart and kidney transplant recipients in Japan was lower than that in European countries. Of note, 42% of viremic transplant patients developed chronic hepatitis.

Objective: To investigate the utility of estimated glomerular filtration rate for assessing kidney function in living kidney donors before and after nephrectomy., Methods: A total of 101 donors underwent inulin clearance measurements before and 1 year after nephrectomy. The mean of three inulin clearance values was used as the measured glomerular filtration rate. Estimated glomerular filtration rate based on serum creatinine and cystatin C levels was calculated using the Japanese estimated glomerular filtration rate equation, Chronic Kidney Disease Epidemiology Collaboration formula and new full age spectrum equation. Age-adjusted chronic kidney disease was defined as glomerular filtration rate <75 mL/min/1.73m 2 for donors aged <40 years, <60 mL/min/1.73m 2 for donors aged 40-65 years and <45 mL/min/1.73m 2 for donors aged >65 years., Results: The postoperative measured glomerular filtration rate <60 mL/min/1.73m 2 and age-adjusted chronic kidney disease rate were 36.0% and 27.0%, respectively. In younger donors (aged <50 years), postoperative measured glomerular filtration rate <60 mL/min/1.73m 2 and age-adjusted chronic kidney disease rates were 5.3% and 26.3%, respectively. In older donors (aged >70 years), postoperative measured glomerular filtration rate <60 mL/min/1.73m 2 and age-adjusted chronic kidney disease rates were 75.0% and 33.3%, respectively. Donor age and measured glomerular filtration rate were significant predictors of postoperative measured glomerular filtration rate. The Japanese estimated glomerular filtration rate equation based on creatinine and cystatin C showed the strongest correlation with measured glomerular filtration rate. However, the Japanese estimated glomerular filtration rate equation based on creatinine overestimated the prevalence of measured glomerular filtration rate <60 mL/min/1.73m 2 , whereas the Japanese estimated glomerular filtration rate based on cystatin C underestimated it., Conclusions: Aged donors might have an increased risk of lower glomerular filtration rate after donor nephrectomy; post-surgery, long-term monitoring of renal function is recommended. Measurement of glomerular filtration rate should be carried out for donors, especially pre-surgery. A more precise glomerular filtration rate equation is required in the future., (© 2019 The Japanese Urological Association.)

Objectives: To assess the impact of preoperative serum sodium concentration on the prognosis of patients with upper urinary tract urothelial carcinoma treated by nephroureterectomy., Methods: The clinical records of 139 patients treated for upper urinary tract urothelial carcinoma by nephroureterectomy were retrospectively reviewed. Recurrence-free and cancer-specific survival curves were calculated using the Kaplan-Meier method, with the difference between curves evaluated using the log-rank test. A multivariate analysis was carried out by Cox's proportional hazard model to identify prognostic factors., Results: The median (range) follow-up time was 27 (1-139) months. The median (range) preoperative serum sodium was 141 (134-147) mEq/L. Five-year cancer-specific survival estimates for patients above and below the median preoperative serum sodium were 81.7% (95% confidence interval: 68.7-89.7) and 50.6% (95% confidence interval: 30.3-67.8), respectively. In the multivariate analysis, preoperative sodium concentration, pathological T stage, and lymphovascular invasion were independent and significant prognostic factors for cancer-specific survival. A prognostic model of risk classification for cancer-specific survival involving these parameters was developed, and 5-year cancer-specific survival estimates were 29.9% (95% confidence interval: 14.5-47.0) for the poor risk group (hazard ratio 19.95 [95% confidence interval: 8.5-46.6]; P < 0.001), 81.6% (95% confidence interval: 55.2-93.3) for the intermediate risk group (hazard ratio 5.70 [95% confidence interval: 1.27-25.5]; P = 0.022) and 97.9% (95% confidence interval 85.9-99.7) for the favorable risk group., Conclusion: These findings suggest for the first time that a low preoperative sodium level predicts a poor survival in upper urinary tract urothelial carcinoma patients treated by nephroureterectomy., (© 2012 The Japanese Urological Association.)

Background: Acute pyelonephritis (APN) is a common complication of ureteral obstruction caused by urolithiasis, and it can be lethal if it progresses to septic shock. We investigated the clinical characteristics of patients undergoing emergency drainage and assessed risk factors for septic shock., Methods: A retrospective study was performed of 98 patients (101 events) requiring emergency drainage at our urology department for obstructive APN associated with upper urinary tract calculi from January 2003 to January 2011. Clinical characteristics were summarized, and risk factors for septic shock were assessed by logistic regression analysis., Results: Objective evidence of sepsis was found in 64 (63.4%) events, and 21 events (20.8%) were categorized as septic shock. Ninety-six patients recovered, but 2 patients died of septic shock. Multivariate analysis revealed that age and the presence of paralysis were independent risk factors for septic shock., Conclusions: APN associated with upper urinary tract calculi is a severe disease that should be treated with caution, particularly when risk factors are present.

Background: The regular dose of an angiotensin II type-1 receptor blocker (ARB) in renal transplant patients for hypertension is shown to be safe and effective; however, information on the appropriate dosing of ARBs in renal transplant patients is limited. We evaluate the efficacy and safety of the maximal dose of candesartan administered to renal transplant patients., Methods: Sixty-nine recipients were enrolled in this study. Patients were divided into three groups based on the basal dose of candesartan: patients not taking candesartan (Group A); patients taking a low to medium dose of candesartan (2-4 mg/day; Group B); and patients taking a high dose of candesartan (8 mg/day; Group C). During the course of the study, the dose of candesartan was gradually increased to a final dose of 12 mg/day. Physiological and biochemical parameters were measured before and after the 12-month study period., Results: Ninety-one percent of patients succeeded in continuing their administration of candesartan for 1 year and 75% tolerated the administration of the maximal dose of candesartan. Significant differences in proteinuria, albuminuria, serum creatinine, and estimated glomerular filtration rate (eGFR) level among the groups were detected. In Group A, candesartan reduced systolic blood pressure, decreased the levels of proteinuria, albuminuria, eGFR, and hemoglobin and increased plasma potassium, creatinine level, and plasma renin activity., Conclusion: The gradual increase of an ARB to its maximal dose in renal transplant patients is safe when carefully monitored. We were able to demonstrate the impact of maximal renin-angiotensin system (RAS) blockade on both proteinuria and albuminuria, which indicates the need for future, long-term randomized prospective trials to further establish the impact of maximal RAS blockade on renal and cardiovascular protection in transplant patients.

Background: Among recipients of renal transplants, the incidences of renal cancer and gastrointestinal cancer are higher and that of skin cancer is much lower in Japan than in Europe and North America., Methods: The risk factors for the development of malignant tumors were examined in Japanese recipients of renal transplants. A total of 556 patients underwent renal transplantation at the Department of Urology, Osaka University Faculty of Medicine between March 1, 1965, and April 31, 2004. Of these patients, 366 were retrospectively studied in whom risk factors potentially related to the development of malignancy could be evaluated on the basis of medical records. The incidence of malignancy, survival rate, and risk factors for malignancy were examined., Results: The overall incidence of malignancy was 6.8% (25/366 patients). Six of the 25 patients with malignancy died of cancer, but there was no correlation between the occurrence of malignancy and the survival rate (P = .8058, log-rank test). A Cox proportional-hazards model identified treatment with tacrolimus (hazard ratio [HR] = 4.376; 95% confidence interval [CI]: 1.647-11.627; P = .0031) and age at transplantation (HR = 1.562; 95% CI: 1.089-2.240; P = .0155) as risk factors for malignancy., Conclusions: The results of multivariate analysis suggested that age at transplantation and the use of tacrolimus were independent risk factors for the development of malignancy in recipients of renal transplants., ((c) 2007 American Cancer Society)

Background: BK virus nephropathy (BKN) is recognized as a cause of graft loss in renal transplant patients. This may be related to the introduction of new and potent immunosuppressive regimens. In Japan, our experience regarding its prevalence, clinical significance, and outcome is still limited. In this study, our primary purpose is to outline the prevalence, outcome, and clinical characteristics of BKN as observed at Osaka University Hospital., Methods: We retrospectively analyzed 112 biopsy specimens from 87 renal transplant patients. All transplantations were from living donors. Of the 112 biopsy specimens, 71 were from protocol biopsies and 41 were from episode biopsies. Calcineurin inhibitors and corticosteroid were used in all patients (tacrolimus 32 and cyclosporin 55). In addition, azathioprine was used in 43 patients, mizoribine was used in 24 patients, and mycophenolate mofetil was used in 20 patients. BKN was diagnosed by light microscopic examination and a positive immunohistochemical staining of anti-SV40 antibody in a biopsy specimen. In order to investigate the outcome and potential risk factors of patients with different histological staging, we divided the patients into groups A (mild histological change) and B (moderate or severe histological change)., Results: Of the 87 patients, six were diagnosed with BKN. There were no significant differences between BKN patients and non-BKN patients, except for the number of patients with graft loss (p < 0.001). Of the six BKN patients, three were in group A, and three were in group B. We recognized a significant difference between group A and group B in terms of anti-rejection treatment including glucocorticoid, tacrolimus trough levels of over 8 ng/mL, episode of acute rejection within 1-month post-transplantation, and the time period between transplantation and BKN diagnosis., Conclusions: This is the first report of BKN in Japanese renal allograft recipients. In our hospital, the prevalence, risk factors, and outcome were similar to those previously for non-Japanese recipients.