Relationship of plasma 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid concentration with OATP1B activity in patients with chronic kidney disease.

Organic anion-transporting polypeptides (OATP)1B are drug transporters mainly expressed in the sinusoidal membrane. Many studies have suggested that OATP1B activity is affected by genetic factor, the uremic toxin 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF), and inflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). Coproporphyrin-I (CP-I) is spotlighted as a highly accurate endogenous substrate of OATP1B. We previously reported a positive correlation between plasma CMPF and CP-I concentrations in patients with chronic kidney disease (CKD). The present study evaluated the impact of genetic polymorphisms, CMPF, IL-6, TNF-α, and estimated glomerular filtration rate (eGFR) on individual differences in OATP1B activity in patients with CKD. Seventy-three patients with CKD who received kidney transplant at least 3 months earlier were analyzed. Plasma CP-I concentration was higher in OATP1B1*15 carriers than in non-carriers. In all patients, CP-I did not correlate significantly with CMPF, IL-6, TNF-α, or eGFR. However, when the dataset was cut off at CMPF concentration of 8 and 7 µg/mL, 4 µg/mL, 3 µg/mL or 2 µg/mL, CMPF correlated positively with CP-I, and correlation coefficient tended to be higher as plasma CMPF concentration was lower. In conclusion, OATP1B1*15 impacted OATP1B activity in patients with CKD, but IL-6 and TNF-α did not. However, the impact of CMPF on OATP1B activity was limited to low CMPF concentrations, and the effect could be saturated at high concentrations. When prescribing an OATP1B substrate drug for patients with CKD, the OATP1B1*15 carrier status and plasma CMPF concentration may need to be considered to decide the dose regimen.

Simple predictors for the completion of scheduled gemcitabine­cisplatin regimens based on real­world urothelial cancer data.

Gemcitabine plus cisplatin (GC) is the standard first line of chemotherapy for urothelial carcinoma. However, it is often difficult to complete scheduled GC therapy because of real-world adverse events. Therefore, the reasons behind delays, scheduled cancelations and determined predictive factors for completing scheduled GC therapy were retrospectively analyzed. Patients diagnosed with locally advanced or metastatic urothelial carcinoma from 2009 to 2020 received a 4-week GC therapy schedule in Oita University Hospital. Information was retrospectively extracted from medical records and all cycles were divided into two groups: One wherein all treatments were administered and completed on schedule and the other wherein treatment was either delayed or canceled in during the treatment schedule. Predictive factors were then statistically extracted between the two groups. In total, 70 patients received 201 cycles of a 4-week scheduled GC therapy. Of the 201 cycles, a total of 68 (33.8%) completed all scheduled treatments, while 133 (66.1%) did not complete the treatment as scheduled. In the group where administration was not completed on schedule, the factors of male, ureteral cancer, lower stage, <90% of gemcitabine and cisplatin dosage, solitary kidney, high creatinine level, low estimated glomerular filtration rate level, low platelet count and high alkaline phosphatase level at the initiation of each cycle were more significant. Additionally, the lowest anticancer drug percentage administration was on day 15. From these results, predictive factors for patients with various backgrounds who completed the scheduled 4-week GC therapy based on real-world data were identified. This information can be useful for clinical physicians when deciding the course of treatment.

Evaluation of the usefulness of plasma 4ß-hydroxycholesterol concentration normalized by 4α-hydroxycholesterol for accurate CYP3A phenotyping.

Plasma 4ß-hydroxycholesterol (OHC) has drawn attention as an endogenous substrate indicating CYP3A activity. Plasma 4ß-OHC is produced by hydroxylation by CYP3A4 and CYP3A5 and by cholesterol autoxidation. Plasma 4α-OHC is produced by cholesterol autoxidation and not affected by CYP3A activity. This study aimed to evaluate the usefulness of plasma 4ß-OHC concentration minus plasma 4α-OHC concentration (4ß-OHC-4α-OHC) compared with plasma 4ß-OHC concentration and 4ß-OHC/total cholesterol (TC) ratio in cross-sectional evaluation of CYP3A activity. Four hundred sixteen general adults were divided into 191 CYP3A5*1 carriers and 225 non-carriers. Twenty-six patients with chronic kidney disease (CKD) with CYP3A5*1 allele were divided into 14 with CKD stage 3 and 12 with stage 4-5D. Area under the receiver operating characteristic curve (AUC) for the three indices were evaluated for predicting presence or absence of CYP3A5*1 allele in general adults, and for predicting CKD stage 3 or stage 4-5D in patients with CKD. There was no significant difference between AUC of 4ß-OHC-4α-OHC and AUC of plasma 4ß-OHC concentration in general adults and in patients with CKD. AUC of 4ß-OHC-4α-OHC was significantly smaller than that of 4ß-OHC/TC ratio in general adults (p = 0.025), but the two indices did not differ in patients with CKD. In conclusion, in the present cross-sectional evaluation of CYP3A activity in general adults and in patients with CKD with CYP3A5*1 allele, the usefulness of 4ß-OHC-4α-OHC was not different from plasma 4ß-OHC concentration or 4ß-OHC/TC ratio. However, because of the limitations in study design and subject selection of this research, these findings require verification in further studies.

A complete response to Pembrolizumab for metastatic collecting duct carcinoma of the kidney.

Collecting duct carcinoma, also known as Bellini duct cancer, is a rare subtype of renal cell carcinoma with a poor prognosis in the metastatic setting. There are limited data to suggest the efficacy of targeted therapy or immune checkpoint inhibitors for collecting duct carcinoma, except for small series and case reports. Herein, we present the case of a patient with collecting duct carcinoma who exhibited a complete response to pembrolizumab and long-term remission approximately 5 years after drug withdrawal.

Impact of Fish Intake Frequency on Cardiovascular Disease-Specific Survival in Hemodialysis Patients.

Introduction: Cardiovascular disease (CVD) is the leading cause of death in hemodialysis patients (HPs). As a food source, fish contains both CVD-preventive and CVD-promoting fatty acids; however, there is no consensus on fish consumption as a preventive measure for CVD in HPs. This single-center longitudinal cohort study aims to assess the impact of fish intake frequency (FIF) per week on CVD in Japanese HPs. Methods: Upon the initiation of the study, 148 HPs were evaluated to determine the FIF, and blood samples were analyzed. These patients were then monitored for 6 years.The relationships between each FIF and blood sampling data, CVD-specific survival (CSS), and new CVD-free survival (nCFS) were statistically calculated using Kaplan-Meier survival curves. Results: During the observation period, 65 deaths were reported, 16 of which were attributed to CVD. Further, 53 patients developed new CVD onset, and no association was found between the FIF and blood sampling data. Based on the Kaplan-Meier survival curves, there was a significant difference in the CSS probability rates at 72 months between patients with an FIF of ≥4 (0.719, 95% confidence interval (CI): 0.530-0.842) and those with an FIF of ≤3 (0.930, 95% CI: 0.851-0.968) (p < 0.01). However, the nCFS probability at 72 months did not significantly differ between patients with an FIF of ≥4 and those with an FIF of ≤3. Multivariate Cox proportional hazards regression showed that an FIF of ≥4 (hazard ratio: 3.64, 95% CI: 1.22-10.9, p = 0.02) was an independent predictor of CSS, but not of nCFS. Conclusions: It was suggested that a higher FIF in HPs might be one of the risks for developing CVD with increased mortality.

IL-6-Producing Pheochromocytoma Associated With Von Hippel Lindau Disease: A Case Report With Literature Review.

We present a first case report of an IL-6-producing pheochromocytoma associated with von Hippel Lindau (vHL) disease. Pheochromocytomas are rare tumors that produce catecholamines, leading to various symptoms. In this case, a 28-year-old woman with a family history of vHL disease presented with a prolonged fever. Laboratory examinations revealed elevated C-reactive protein levels, and notably, a significantly increased serum IL-6 level. Imaging studies confirmed bilateral adrenal tumors with increased uptake on fluorodeoxyglucose-positron emission tomography and 123I-metaiodobenzylguanidine scintigraphy in the right adrenal gland. Despite partial relief with nonsteroidal anti-inflammatory drugs and alpha-blockers, her fever persisted until prednisolone administration, which promoted a complete resolution. A histopathological analysis following a right laparoscopic adrenalectomy revealed a typical pheochromocytoma. We conducted further analyses, including an enzyme-linked immunosorbent assay (ELISA), a quantitative real-time polymerase chain reaction (PCR) test, and immunoblot assays from the resected tumor tissues. We compared the current case with other cases of pheochromocytoma that presented neither elevated serum IL-6 nor high fever. Using ELISA, we found that this patient exhibited more IL-6 secretion than that seen in other cases. Additionally, quantitative real-time PCR and immunoblot found that both the phosphorylated signal transducer and activator of transcription 3 (STAT3) messenger RNA (mRNA) and protein expression levels exceeded those of the other cases. Thus, we surmised that IL-6 was produced directly from the tumor tissue and IL-6 expression was potentiated through the IL-6/STAT3 signaling pathway. Our findings contribute to the understanding of IL-6-producing pheochromocytomas and their distinct clinical characteristics.

Clinicopathological characteristics of adrenocortical carcinoma in the Kyushu-Okinawa area of Japan.

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.

External iliac arterial dissection after robot-assisted radical cystectomy with an intracorporeal ileal conduit and extended pelvic lymph node dissection.

Introduction: External iliac arterial dissection after robot-assisted laparoscopic procedures is an extremely rare complication. It may cause severe adverse outcomes, such as lower limb necrosis. Case presentation: A 73-year-old man was diagnosed with cT2 ≤ N0M0 bladder cancer and underwent robot-assisted radical cystectomy. After surgery, he complained of severe left lower leg pain. Computed tomography showed external iliac arterial occlusion. Furthermore, the emergency operation revealed external iliac arterial dissection and occlusion. Conclusion: The robot arm does not have any sense of force or touch. Thus, it is necessary to pay sufficient attention to the traction of blood vessels and contact with major organs.

Current magnetic resonance imaging-based diagnostic strategies for prostate cancer.

Recent developments in multiparametric MRI and MRI-targeted biopsy have made it possible to detect clinically significant cancers more accurately and efficiently than ever before. Furthermore, software that enables easy MRI/US image fusion has been developed and is already available on the market, and this has provided a tailwind for the spread of MRI-based prostate cancer diagnostic strategies. Such precise diagnosis of prostate cancer localization is essential for highly accurate focal therapy. In addition, a recent large-scale study applying MRI to community screening for prostate cancer has reported its usefulness. By contrast, concerns about overdiagnosis and overtreatment, the existence of inter-reader variability in MRI diagnosis, and issues with current MRI-targeted biopsy have emerged. In this article, we review the development of multiparametric MRI and MRI-targeted biopsy to date and the current issues and discuss future directions.

A case of adrenal myelolipoma complicated with Prader-Willi syndrome.

Introduction: Prader-Willi syndrome is a congenital disorder that occurs in one in 10 000-30 000 children and is characterized by obesity, short stature, and intellectual disability. Case presentation: A 24-year-old male patient with Prader-Willi syndrome presented with an enlarged adrenal tumor. Computed tomography detected a well-defined mass. Magnetic resonance imaging revealed an increased signal intensity predominantly in fatty areas, suggesting adrenal myelolipoma. Laparoscopic left adrenalectomy was performed. Postoperatively, the patient developed mild pulmonary atelectasis, myelolipoma was confirmed by histopathology, and there was no recurrence at approximately 2 years postoperatively. Conclusion: This is the first report of Prader-Willi syndrome complicated with adrenal myelolipoma, which was removed laparoscopically.

A case of intrascrotal extratesticular schwannoma.

Schwannomas are benign tumors arising from Schwann cells, which compose the myelin sheath covering peripheral nerves. Although schwannomas can develop in various locations throughout the human body, the scrotum is a rare site for development of a schwannoma. Furthermore, to the best of our knowledge, no study to date has focused on the detailed imaging findings of intrascrotal schwannoma.

Evaluation of effects of indoxyl sulfate and parathyroid hormone on CYP3A activity considering the influence of CYP3A5 gene polymorphisms.

AIMS: Indoxyl sulfate and parathyroid hormone (PTH), which accumulate in chronic kidney disease (CKD), have been reported to reduce cytochrome P450(CYP)3A activity. Homozygotes of the CYP3A5*3 allele have reduced CYP3A5 activity compared to carriers of at least one CYP3A5*1 allele. 4ß-Hydroxycholesterol (4ß-OHC) has been established as an endogenous substrate reflecting CYP3A activity. 4ß-OHC is produced through hydroxylation by CYP3A4 and CYP3A5 and by autoxidation of cholesterol, whereas 4α-hydroxycholesterol (4α-OHC) is produced solely by autoxidation of cholesterol. This study focused on CKD patients and evaluated the effects of plasma indoxyl sulfate and intact-PTH concentrations on plasma 4ß-OHC concentration, 4ß-OHC/total cholesterol ratio and 4ß-OHC-4α-OHC, with consideration of the influence of CYP3A5 polymorphism. METHODS: Sixty-three CKD patients were analysed and divided into CYP3A5 carrier group (n = 26) and non-carrier group (n = 37). RESULTS: Plasma indoxyl sulfate significantly correlated inversely with 4ß-OHC concentration and with 4ß-OHC-4α-OHC in both the CYP3A5*1 carrier group (r = -0.42, P = .034; r = -0.39, P = .050, respectively) and the non-carrier group (r = -0.45, P = .0054; r = -0.39, P = .019, respectively). However, multiple regression analysis did not identify plasma indoxyl sulfate concentration as a significant independent factor associated with any of the CYP3A activity indices. There was no significant correlation between plasma intact-PTH concentration and any of the CYP3A activity indices. CONCLUSIONS: The present results suggest that plasma indoxyl sulfate and intact-PTH concentrations do not have clinically significant effects on CYP3A activity in patients with CKD.

Real-world treatment outcomes of patients with penile cancer in the Kyushu-Okinawa area of Japan in the pre-guideline era.

OBJECTIVES: To understand the real-world outcomes for patients with penile cancer in the Kyushu-Okinawa area before the introduction of practice guidelines in Japan. METHODS: We retrospectively collected medical information on patients with penile squamous cell carcinoma and penile intraepithelial neoplasia at 12 university hospitals and their affiliated hospitals in the Kyushu-Okinawa area from January 2009 to December 2020. Patients with unknown clinical stage were excluded. Patient background characteristics and survival, as well as pretreatment factors involved in survival, were investigated. RESULTS: A total of 196 patients were included. Patients with clinical stage 0, I, IIA, IIB, IIIA, IIIB and IV comprised 9.7, 26.0, 22.4, 2.6, 10.7, 14.3 and 14.3%, respectively. The median follow-up was 26 months, and the mean 5-year overall survival and cancer-specific survival rates were 74.3 and 79.8%, respectively. On univariate analysis, tumor diameter ≥ 30 mm, penile shaft tumor, Eastern Cooperative Oncology Group performance status ≥ 1, cT ≥ 3, cN ≥ 2 and cM1 were associated with significantly poorer cancer-specific survival. On multivariate analysis, pretreatment factors of cN ≥ 2 (hazard ratio, 32.5; 95% confidence interval, 5.08-208; P = 0.0002), Eastern Cooperative Oncology Group performance status ≥ 1 (4.42; 1.79-10.9; P = 0.0012) and cT ≥ 3 (3.34; 1.11-10.1; P = 0.0319) were identified as independent prognostic factors. CONCLUSIONS: The study revealed basic data for future penile cancer treatment and research, including survival rates according to clinical stages, and identified cN ≥ 2, Eastern Cooperative Oncology Group performance status ≥ 1 and cT ≥ 3 at initial diagnosis as independent prognostic factors. Evidence for penile cancer in Japan is particularly scarce, and future large-scale prospective studies are warranted.

A Rare Case of Hernia Incarceration Under the Closed Port-Site Fascia After Robot-Assisted Laparoscopic Radical Cystectomy: Insights and Management Strategies.

Most cases of port-site hernia were due to inadequate fascial closure of the port site. We experienced a rare case of hernia incarceration under the closed port-site fascia despite adequate closure of the fascia after robot-assisted laparoscopic radical cystectomy. In this case, the small intestine was incarcerated between the transversus abdominis and oblique abdominal muscles from the 12-mm trocar site for the assistant. We inserted forceps to release the incarceration, and the fascia and peritoneum of the port site were closed using a trocar site closure device under laparoscopy. We considered that all-layer suturing, including peritoneum and inner and outer oblique fascia suturing, was necessary for port-site closure, especially in patients with obesity, because hernias can occur with fascial closure alone.

Pitfalls in the diagnosis and treatment of a hypertensive patient with unilateral primary aldosteronism and contralateral pheochromocytoma: a case report.

BACKGROUND: Primary aldosteronism (PA) is a common cause of secondary hypertension, whereas pheochromocytoma is a rare cause of it. Thus, concomitant PA and pheochromocytoma is a very rare condition. CASE PRESENTATION: A 52-year-old woman was admitted to our hospital with suspected PA based on the presence of hypertension, spontaneous hypokalemia, and a high aldosterone-to-renin ratio. She had no catecholamine excess symptoms other than hypertension. Abdominal computed tomography (CT) showed a right lipid-rich adrenal mass and a left lipid-poor adrenal mass. PA was diagnosed by the captopril challenge test. The 24-h urinary fractionated metanephrines were slightly elevated. Adrenal vein sampling (AVS) confirmed that the right adrenal gland was responsible for aldosterone hypersecretion. Medical therapy with eplerenone was started because the patient refused surgery. Five years later, she requested surgery for PA. The second AVS confirmed right unilateral hyperaldosteronism, as expected. Repeated abdominal CT showed the enlargement of the left adrenal mass. The 24-h urinary fractionated metanephrines had risen to the diagnostic level. 123I- metaiodobenzylguanidine (MIBG) scintigraphy showed a marked tracer uptake in the left adrenal mass with no metastatic lesion. After preoperative management with α-blockade, laparoscopic left partial adrenalectomy was performed. Immunohistochemical examination of the tumor showed chromogranin A positivity leading to the diagnosis of left pheochromocytoma. CONCLUSIONS: We report an extremely rare case of concomitant unilateral PA and contralateral pheochromocytoma. When diagnosing unilateral PA by AVS, especially in cases with a lipid-poor adrenal mass, clinicians should rule out the possibility of the presence of pheochromocytoma before proceeding to undergo unilateral adrenalectomy. Although there is no standard treatment for this rare condition, it is essential to select personalized treatment from the perspective of conserving the adrenal gland.

A multicenter survey of effects and challenges of an 8K ultra-high-definition endoscopy system compared to existing endoscopy systems for endoscopic surgery.

INTRODUCTION: 8K ultra-high-definition (UHD) images enabling clearer recognition of anatomical structures could contribute to further development of surgical techniques and advanced applications in endoscopic surgery fields. This study aimed to clarify effects and challenges of endoscopic surgery with 8K UHD endoscopy compared to existing endoscopy systems. METHODS: In this multicenter, cross-sectional, questionnaire survey, data were collected from surgical participants who newly used and observed 8K UHD endoscopy in patients undergoing surgery from February 2020 to February 2021. Survey items included sense of presence, reality, depth perception, visibility of tissue, eyestrain, and degree of satisfaction for operators and observers, and weight, operability, focus adjustment, physical fatigue, eyestrain, and satisfaction for camera assistants. Participants rated each 8K UHD endoscopic surgery on a one-to-five scale (definitively inferior, relatively inferior, equivalent, relatively superior, definitively superior) compared to the existing endoscopy system of each facility. RESULTS: Overall, questionnaire responses from 139 participants assessing 8K UHD endoscopic surgery were collected from surgeries performed in 46 patients. Respective ratings of operators and observers included sense of presence: "superior or relatively superior", 97.8% and 91.5%; reality: "superior or relatively superior", 76.1% and 72.3%; and visibility of tissue: "superior or relatively superior", 93.5% and 87.2%. Weight was rated as "inferior or relatively inferior" by 73.9% of camera assistants and focus adjustment as "inferior" by 60.9% of them. CONCLUSIONS: 8K UHD endoscopic surgery enabled identification of surgical anatomies more clearly, provided a sense of presence and reality, and might improve educational effect. Technological development is expected to reduce the burden of camera assistants.

Involvement of clusterin expression in the refractory response of pancreatic cancer cells to a MEK inhibitor.

Constitutive activation of the mitogen-activated protein kinase (MAPK) signaling pathway is essential for tumorigenesis of pancreatic ductal adenocarcinoma (PDAC). To date, however, almost all clinical trials of inhibitor targeting this pathway have failed to improve the outcome of patients with PDAC. We found that implanted MIA Paca2, a human PDAC cell line sensitive to a MAPK inhibitor, PD0325901, became refractory within a week after treatment. By comparing the expression profiles of MIA Paca2 before and after acquisition of the refractoriness to PD0325901, we identified clusterin (CLU) as a candidate gene involved. CLU was shown to be induced immediately after treatment with PD0325901 or expressed primarily in more than half of PDAC cell lines, enhancing cell viability by escaping from apoptosis. A combination of PD0325901 and CLU downregulation was found to synergistically or additively reduce the proliferation of PDAC cells. In surgically resected PDAC tissues, overexpression of CLU in cancer cells was observed immunohistochemically in approximately half of the cases studied. Collectively, our findings highlight the mechanisms responsible for the rapid refractory response to MEK inhibitor in PDAC cells, suggesting a novel therapeutic strategy that could be applicable to patients with PDAC using inhibitor targeting the MAPK signaling pathway and CLU.

A case of retroperitoneal venous malformation resected by laparoscopic surgery.

Introduction: Among vascular malformations, venous malformations are the most common type. Among these, retroperitoneal venous malformations are extremely rare. Case presentation: A 60-year-old woman was diagnosed with a retroperitoneal tumor 4.5 cm in diameter by abdominal computed tomographic scan. We had difficulty judging whether the tumor was benign or malignant. We performed laparoscopic surgery in order to remove the tumor and make a precise diagnosis. The pathological diagnosis was a venous malformation. Conclusion: Venous malformation located in the retroperitoneum is very rare, and there were few cases that could be removed by laparoscopic surgery. Laparoscopic surgery may be beneficial both for treatment and diagnosis of patients with a small retroperitoneal venous malformation.

Mamushi bites in a kidney transplant recipient.

Introduction: Mamushi bites are the most common venomous snakebites in Japan. The clinical course of a common mamushi bite is known, and its alarming complication and cause of death are acute renal failure due to the venom. However, reports of mamushi bites in kidney transplant recipients are lacking, and the clinical course is unknown. Case presentation: A 66-year-old man who was bitten by a mamushi 3 years after kidney transplantation. Similar to the course of a typical mamushi bite, his severity gradually worsened to its peak 3 days after the bite, after which he turned lightly. A sufficient amount of infusion and continued immunosuppressive drugs were used to avoid acute renal failure. Conclusion: Even if the mamushi bite occurs in a kidney transplant recipient, the course and management may be the same as usual by continuing the immunosuppressive drugs and a sufficient amount of infusion.

Serum IgG4 Concentration Is a Potential Predictive Biomarker in Glucocorticoid Treatment for Idiopathic Retroperitoneal Fibrosis.

OBJECTIVES: To evaluate the management and outcome of idiopathic retroperitoneal fibrosis (iRPF) in Japan, and to identify its clinical biomarker. METHODS: We retrospectively analyzed 129 patients with iRPF treated between January 2008 and May 2018 at 12 university and related hospitals. Patients treated with glucocorticoid were analyzed to identify a predictive biomarker. These patients were classified into three groups according to overall effectiveness (no change: NC, complete response: CR, and partial response groups: PR), and each parameter was compared statistically. RESULTS: Male-female ratio was 5:1, and median age at diagnosis was 69 (33-86) years. Smoking history was reported in 59.6% of the patients. As treatment, 95 patients received glucocorticoid therapy with an overall response rate of 84%. As a result, serum concentration of IgG4 was significantly decreased in NC group compared with the other two groups (56.6 mg/dL vs. 255 mg/dL, 206 mg/dL, p = 0.0059 and 0.0078). ROC analysis was performed between the nonresponder (NC) and responder groups (CR + PR) to identify the cut-off value of serum IgG4 as a predictive marker. As a result, AUC of 0.793 was confirmed. CONCLUSIONS: Pre-treatment serum IgG4 concentration may have potential as a predictive biomarker of steroid treatment.