Clinical effects of tacrolimus blood concentrations early after allogeneic hematopoietic stem cell transplantation.

BACKGROUND AIMS: Tacrolimus (TAC) plus short-term methotrexate (stMTX) is used for graft-versus-host disease (GVHD) prophylaxis after allogeneic hematopoietic stem cell transplantation (allo-HSCT). TAC blood concentrations are frequently adjusted to enhance the graft-versus-leukemia/lymphoma effect or attenuate severe GVHD. Limited information is available on the clinical impact of these adjustments and the optimal time to perform them in order to achieve good clinical outcomes. METHODS: We retrospectively analyzed 211 patients who underwent allo-HSCT at our institutes. RESULTS: Higher TAC concentrations in week 3 correlated with a significantly higher cumulative incidence of relapse (CIR) (P = 0.03) and lower nonrelapse mortality (P = 0.04). The clinical impact of high TAC concentrations in week 3 on CIR was detected in the refined disease risk index: low/intermediate (P = 0.04) and high (P < 0.01), and conditioning regimens other than cyclophosphamide/total body irradiation and busulfan/cyclophosphamide (P = 0.07). Higher TAC concentrations in week 1 correlated with a lower grade 2-4 acute GVHD rate (P = 0.01). Higher TAC concentrations in weeks 2 and 3 correlated with slightly lower (P = 0.05) and significantly lower (P = 0.02) grade 3-4 acute GVHD rates, respectively. Higher TAC concentrations in weeks 1 and 3 were beneficial for severe acute GVHD in patients with a human leukocyte antigen-matched donor (P = 0.03 and P < 0.01, respectively), not treated with anti-thymocyte globulin (P = 0.02 and P = 0.02, respectively), and receiving three stMTX doses (P = 0.03 and P = 0.02, respectively). CONCLUSIONS: The clinical impact of TAC concentrations varied according to patient characteristics, including disease malignancy, conditioning regimens, donor sources, and GVHD prophylaxis. These results suggest that TAC management needs to be based on patient profiles.

Prognostic impact of the simple L-index and absolute lymphocyte count early after allogeneic hematopoietic stem cell transplantation.

BACKGROUND AIMS: The L-index, designed as a quantitative parameter to simultaneously assess the duration and severity of lymphopenia, and absolute lymphocyte count (ALC) have a prognostic impact after allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, discrepancies have been reported in the impact of ALC, and limited information is currently available on the L-index. METHODS: To search for a better clinical tool, the authors retrospectively compared the simple L-index at 30 days (sL-index(30)), which aims to make the original L-index more compact, and ALC at 30 days (ALC(30)) after allo-HSCT in 217 patients who underwent allo-HSCT at the authors' institutions. RESULTS: Median sL-index(30) was 11 712 (range, 4419-18 511) and median ALC(30) was 404 (range, 0-3754). In a multivariate analysis, higher sL-index(30) was associated with a significantly higher cumulative incidence of relapse (CIR) (hazard ratio [HR], 1.01, 95% confidence interval [CI], 1.00-1.02, P = 0.02 for every increase of 100 in sL-index(30)) as well as non-relapse mortality (NRM) (HR, 1.02, 95% CI, 1.00-1.03, P = 0.01 for every increase of 100 in sL-index(30)). Although higher ALC(30) was associated with significantly lower CIR (HR, 0.94, 95% CI, 0.89-1.00, P = 0.04 for every increase of 100/µL in ALC(30)), it was not extracted as an independent risk factor for NRM (HR, 0.96, 95% CI, 0.88-1.05, P = 0.39). Higher sL-index(30) was associated with a slightly higher rate of grade 3-4 acute graft-versus-host disease (GVHD) (HR, 1.02, 95% CI, 1.00-1.04, P = 0.12 for every increase of 100 in sL-index(30)) but not chronic GVHD (HR, 1.00, 95% CI, 0.99-1.01, P = 0.63). ALC(30) was not associated with rates of grade 3-4 acute GVHD (HR, 1.02, 95% CI, 0.88-1.17, P = 0.81) or chronic GVHD (HR, 1.02, 95% CI, 0.98-1.06, P = 0.34). In a receiver operating characteristic curve, the cutoff values of sL-index(30) and ALC(30) for CIR were 9000 and 500, respectively, and the cutoff value of sL-index(30) for NRM was 12 000. CONCLUSIONS: sL-index(30) is a promising tool that may be applied to various survival outcomes. A large-scale prospective study is needed to clarify whether medical interventions based on sL-index(30) values will improve the clinical prognosis of patients.

Sequential immune-targeted surgical therapy resulted in disease-free survival in a case with advanced renal cell carcinoma.

BACKGROUND: Currently, immunotherapy is indicated for patients with metastatic RCC or unresectable RCC, but there is no indication for immunotherapy in the neoadjuvant setting. We report a case in which the combined use of nivolumab and ipilimumab and sequential TKI therapy enabled surgical treatment. CASE PRESENTATION: A 71-year-old female was diagnosed with a metastatic clear-cell renal cell carcinoma with a level IV tumor thrombus. She was started on nivolumab-ipilimumab therapy, and was switched to pazopanib monotherapy because the tumor thrombus progressed within the right atrium. The tumor shrank to resectable status with sequential therapy. She then underwent right nephrectomy and thrombectomy. Pathological analysis showed 10-20% residual tumor in the primary tumor, but no viable cells in tumor thrombus. She remains clinically disease-free 1 year after surgery. CONCLUSION: This case suggests the utility of sequential immune-targeted therapy as neoadjuvant therapy in advanced renal cell carcinoma.

A low RENAL Nephrometry Score can avoid the need for the intraoperative insertion of a ureteral catheter in robot-assisted partial nephrectomy.

BACKGROUND: Intraoperative urinary collecting system entry (CSE) in robot-assisted partial nephrectomy (RAPN) may cause postoperative urinary leakage and extend the hospitalization. Therefore, identifying and firmly closing the entry sites are important for preventing postoperative urine leakage. In RAPN cases expected to require CSE, we insert a ureteral catheter and inject dye into the renal pelvis to identify the entry sites. We retrospectively analyzed the factors associated with intraoperative CSE in RAPN and explored the indications of intraoperative ureteral catheter indwelling in RAPN. METHODS: Of 104 Japanese patients who underwent RAPN at our institution from August 2016 to March 2020, 101 were analyzed. The patients were classified into CSE and non-CSE groups. The patients' background characteristics, RENAL Nephrometry Score (RNS), and surgical outcomes were analyzed. RESULTS: Intraoperative CSE was observed in 41 patients (41%). The CSE group had a significantly longer operative time, console time, ischemic time, and hospital stay than the non-CSE group. In a multivariable analysis, the N-score (odds ratio [OR] = 3.9, P < 0.05) and RNS total score excluding the L-score (OR = 3.1, P < 0.05) were associated with CSE. In a logistic regression analysis, CSE showed a moderate correlation with the RNS total score excluding the L-score (AUC 0.848, cut-off 5, sensitivity 0.83, specificity 0.73). CONCLUSION: A ureteral catheter should not be placed in patients with an RNS total score (excluding the L-score) of ≤ 4.

Predictors of Hypotension after Adrenalectomy for Pheochromocytoma.

The management of blood pressure is a significant concern for surgeons and anesthesiologists performing adrenalectomy for pheochromocytoma. We evaluated clinical factors in pheochromocytoma patients to identify the predictors of postoperative hypotension. The medical records of patients who underwent adrenalectomy for pheochromocytoma between 2001 and 2017 were retrospectively reviewed and clinical and biochemical data were evaluated. Of 29 patients, 13 patients needed catecholamine support in the perisurgical period while 16 patients did not. There were significant differences in median age, tumor size, and blood pressure drop (maxmin) between the 2 groups (68 vs 53 years old, p=0.045; 50 vs 32 mm diameter, p=0.022; 110 vs 71 mmHg, p=0.015 respectively). In univariate logistic analysis, age > 65.5 years, tumor size > 34.5 mm, urine metanephrine > 0.205 mg/day and urine normetanephrine > 0.665 mg/day were significant predictors of prolonged hypotension requiring postoperative catecholamine support. Tumor size and urine metanephrine and urine normetanephrine levels were correlated with postoperative hypotension. These predictors may help in the safe perioperative management of pheochromocytoma patients treated with adrenalectomy.

Feasibility of Laparoscopic Radical Cystectomy in Elderly Patients: A Comparative Analysis of Clinical Outcomes in a Single Institution.

Laparoscopic radical cystectomy (LRC) is a standard surgical treatment for muscle-invasive bladder cancer and high-risk non-muscle-invasive bladder cancer. LRC is a less invasive modality than conventional open surgery. Therefore, even elderly patients with invasive bladder cancer may be candidates for LRC. In this study, a comparative analysis of perioperative/oncological outcomes between elderly patients and younger patients who underwent LRC was performed to assess the feasibility of LRC in elderly patients. Sixty-eight consecutive patients who underwent LRC between October 2013 and March 2018 were enrolled and stratified into those younger than 75 years (n=37) and those ≥ 75 years old (n=31). The median follow-up period was 28.2 months. The preoperative and operative parameters and complications were similar in both groups. The 2-year overall survival (OS) was 64.4% in the younger vs. 76.4% in the elderly group (p=0.053), cancer-specific survival (CSS) was 79.3% vs. 81.7% (p=0.187), and recurrence-free survival (RFS) was 58.2% vs. 75.7% (p=0.174), respectively. No significant differences were observed in OS, CSS, or RFS between the groups. No significant differences were found between the groups with respect to peri-surgical/oncological outcomes. We conclude that LRC is feasible in elderly patients.

New classification of hydronephrosis on 18F-FDG-PET/CT predicts post-operative renal function and muscle-invasive disease in patients with upper urinary tract urothelial carcinoma.

OBJECTIVES: To evaluate the value of a classification of hydronephrosis on 18F-flurodeoxyglucose (FDG)-PET/CT in predicting post-operative renal function and pathological outcomes among patients with upper urinary tract urothelial carcinoma. METHODS: We retrospectively reviewed 71 patients treated with nephroureterectomy (NU) for upper urinary tract urothelial carcinoma after FDG-PET/CT between 2010 and 2016. Eight patients treated with ureteral stent or nephrostomy at the time of FDG-PET/CT were excluded. We classified hydronephrosis based on renal excretion of FDG as follows: Type 0, no hydronephrosis; Type 1, hydronephrosis with FDG excretion; and Type 2, hydronephrosis without FDG excretion. eGFR was recorded before pre-operataive FDG-PET/CT examination and after nephroureterectomy. RESULTS: Thirty-three patients (52%) had hydronephrosis, classified as Type 1 in 19 patients (30%) and Type 2 in 14 (22%). Type 2 hydronephrosis was associated with ureteral cancer and severe hydronephrosis on CT. Median changes in eGFR before and after nephroureterectomy in patients classified as Type 0, 1 and 2 were -23.9, -18.8 and 2.0 ml/min/1.73 m2, respectively. On multivariate analysis, Type 2 hydronephrosis was a significant predictor of change in eGFR (P = 0.001). Rates of muscle-invasive upper urinary tract urothelial carcinoma among Type 0, 1 and 2 patients were 37, 42 and 86%, respectively. On multivariate analysis, Type 2 hydronephrosis was a significant predictor of muscle-invasive upper urinary tract urothelial carcinoma (P = 0.032, OR 6.491). CONCLUSIONS: This classification of hydronephrosis from FDG-PET/CT is simple and useful for predicting post-operative renal function and muscle-invasive disease in patients with upper urinary tract urothelial carcinoma, especially with ureteral cancer. This classification can help in deciding eligibility for lymphadenectomy or perioperative cisplatin-based chemotherapy.

Role of robot-assisted radical prostatectomy in locally advanced prostate cancer.

Locally advanced prostate cancer is regarded as a very high-risk disease with a poor prognosis. Although there is no definitive consensus on the definition of locally advanced prostate cancer, radical prostatectomy for locally advanced prostate cancer as a primary treatment or part of a multimodal therapy has been reported. Robot-assisted radical prostatectomy is currently carried out even in high-risk prostate cancer because it provides optimal outcomes. However, limited studies have assessed the role of robot-assisted radical prostatectomy in patients with locally advanced prostate cancer. Herein, we summarize and review the current knowledge in terms of the definition and surgical indications of locally advanced prostate cancer, and the surgical procedure and perisurgical/oncological outcomes of robot-assisted radical prostatectomy and extended pelvic lymphadenectomy for locally advanced prostate cancer.

[Low-Dose Estramustine Phosphate Monotherapy in Castration-Resistant Prostate Cancer Patients].

We retrospectively evaluated the efficacy and toxicity of low-dose estramustine phosphate (EMP) monotherapy in patients with castration-resistant prostate cancer (CRPC). We administered EMP at 140 or 280 mg/day to 89 patients between January 2003 and December 2012. None of the patients were receiving concomitant dexamethasone and none had ever been treated with docetaxel. Fifty-three patients (59.6%) experienced a decline in prostate-specific antigen (PSA) levels, including 20 (22.5%) with a decline of more than 50%. The median time to PSA progression was 90 days. PSA-progression-free survival was significantly longer in patients treated with EMP 140 mg compared with patients treated with EMP 280 mg, and there was no significant difference in the incidence of adverse events between the two groups. The most frequent toxicities were nausea and anorexia. Two patients had grade 3 adverse events of pulmonary embolism and liver dysfunction. EMP treatment was discontinued in nine patients (10.1%) because of side effects (nausea and anorexia in 7, liver dysfunction and lacunar infarction in 1). Low-dose EMP monotherapy is well tolerated and can effectively reduce PSA levels.

[A Case of Bisphosphonate-Related Osteonecrosis of the Jaw with Difficulty in Treatment].

A 65-year-old man with urination difficulty visited our hospital. Because his prostate-specific antigen level was 1,619 ng/ml, we performed a prostate biopsy. The biopsy specimen yielded a diagnosis of adenocarcinoma with a Gleason score of 4＋4. Computed tomography and bone scintigraphy showed lymph node, lung, and bone metastasis (cT3bN1M1). After 13 months of combined androgen blockade, he underwent treatment with a bisphosphonate. At 22 months of treatment, he developed bisphosphonate-related osteonecrosis of the jaw, and all necrotic bone and teeth were removed. He subsequently underwent repeated cleaning and fixation (splinting) for an oral fistula and mandibular fracture. Emergency transcatheter arterial embolization was then performed to treat a bleeding of the facial artery aneurysm. An oral infection and aspiration pneumonia repeatedly developed secondary to the oral fistula. The patient underwent a gastrostomy, after which his nutritional status improved and he was discharged.

Fluorodeoxyglucose positron emission tomography/computed tomography for diagnosis of upper urinary tract urothelial carcinoma.

BACKGROUND: The purpose of this study was to assess the ability of fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) to detect upper urinary tract urothelial carcinomas (UTUC) compared with pathological examination of tissues obtained by ureteroscopic biopsy and split cytologic analysis of urine obtained after retrograde pyelography. METHODS: Clinicopathological records of patients at our institution were retrospectively reviewed. Fifty patients with clinically suspected UTUC, who were histologically diagnosed by nephroureterectomy, partial ureterectomy, or endoscopic biopsy, were included. The patient cohort included 42 men and 8 women, with a median age of 73 (range 54-92) years. RESULTS: Only 27 % of 49 patients with UTUC had positive voided urine cytology, and 33 % of 40 patients had positive split urine cytology. In addition, 40 % of 10 patients had a positive endoscopic biopsy. However, 83 % of 48 patients with UTUC had positive results from FDG-PET/CT examination. The positive predictive value of FDG-PET/CT was 95 %. There were no correlations between sensitivity and tumor stage or tumor grade. Sensitivity of FDG-PET/CT for patients with and without diabetes mellitus was 60 and 89 %, respectively. CONCLUSIONS: These preliminary results from a small number of patients revealed that FDG-PET/CT enabled effective detection of UTUC.

[LAPAROSCOPIC ADRENALECTOMY: COMPARISON OF TRANSPERITONEAL AND RETROPERITONEAL APPROACHES].

OBJECTIVE: Laparoscopic adrenalectomy is generally performed by either a transperitoneal approach (TA) or a retroperitoneal approach (RA). However, the optimal selection criteria for each approach are unclear. We investigated the factors affecting the safety of laparoscopic adrenalectomy to evaluate the optimal criteria for each approach. PATIENTS AND METHODS: In total, 149 patients who underwent laparoscopic adrenalectomy from February 1994 to July 2013 were retrospectively analyzed. We performed TA for 75 tumors in 73 patients and RA for 78 tumors in 76 patients. Patient characteristics and operative outcomes were compared between the two groups. Furthermore, operative outcomes in patients with some surgical risks were specifically compared between the two approaches. RESULTS: Patient characteristics were similar between the two groups, although the patients in the RA group were significantly older than those in the TA group. Four patients with a large pheochromocytoma in the TA group had excessive blood loss and one of them was given blood transfusion. However, there was no difference in intraoperative blood loss (p = 0.091). The other serious adverse events were not observed. CONCLUSIONS: The present findings suggest that both RA and TA can be effective surgical strategies, with close attention to large pheochromocytoma to avoid excessive hemorrhage.

Modified FOLFOX6 chemotherapy in patients with metastatic urachal cancer.

BACKGROUND: To improve the prognosis of patients with urachal cancer and establish an effective chemotherapeutic regimen for distant metastases. METHODS: We conducted a retrospective study to evaluate the efficacy and safety of a modified combination of 5-fluorouracil, leucovorin and oxaliplatin (mFOLFOX6) therapy in patients with metastatic urachal cancer. RESULTS: Five patients were treated with mFOLFOX6. Their median age was 65 years (range 41-80). The median follow-up time was 42 months (range 18-46). Two of the 5 patients (40%) showed an objective response: 1 achieved a clinically complete response and 1 a partial response. The grade 3/4 toxicity associated with this regimen was primarily neutropenia, but febrile neutropenia was not observed. Oxaliplatin treatment was discontinued because of a grade 2 allergic reaction in 1 patient. Grade 2 peripheral sensory neuropathy caused by oxaliplatin was observed in 2 patients, and the OPTIMOX (stop and go) approach had to be adopted. CONCLUSIONS: mFOLFOX6 appears to be effective for the treatment of metastatic urachal cancer.

Combined chemotherapy with gemcitabine and carboplatin for metastatic urothelial carcinomas in patients with high renal insufficiency.

BACKGROUND: This was a retrospective study to evaluate the activity and toxicity of a combined chemotherapeutic regimen of gemcitabine and carboplatin (GCa) in patients with metastatic urothelial carcinomas (UCs) with special regard to patients with highly impaired renal function. METHODS: Eleven patients whose creatinine clearance was 30 ml/min or under and who had been diagnosed with metastatic UC were treated with GCa. The patient cohort comprised 4 males and 7 females, with a median age of 74 (range 67-84) years. The median follow-up was 19 (range 1-58) months. RESULTS: Five of the 11 patients (45%) showed an objective response, with 2 achieving a clinically complete response and 3 a partial response with GCa. The grade 3/4 toxicity of the regimen was primarily hematological, including anemia (55%), neutropenia (45%), and thrombocytopenia (45%). Four patients (36%) could not complete the treatment in total. Grade 3 pneumonitis was found in one patient, and the treatment was terminated. Grade 4 febrile neutropenia occurred in the patient on hemodialysis, and the patient was forced to discontinue the chemotherapy. Another 2 patients also called off the treatment due to a pulmonary adverse event and an elevation of serum creatinine, respectively. CONCLUSIONS: GCa appears to be effective for the treatment of metastatic UCs in patients with impaired renal function, but it is necessary to pay attention to the occurrence of severe adverse events.

[A case of neurosurgery for meningioma in a chronic hemodialysis patient: perioperative management of chronic hemodialysis patients requiring neurosurgery].

Here, we report a case of primary intracranial tumor in a chronic hemodialysis patient in which neurosurgery was successful. A 50-year-old man who had been on hemodialysis for 4 years was admitted to our hospital with general fatigue. Neurological examination on admission revealed mild restless. Computed tomography and magnetic resonance imaging performed on admission revealed a large (55 mm×40 mm) tumor mass in contact with the falx. The size of this tumor rapidly increased over the next month. 201Thallium-chloride single photon emission computed tomography revealed abnormal uptake in the same location as the lesion. This suggested a malignant brain tumor and surgical excision was scheduled. Two weeks prior to surgery, frequent hemodialysis was performed using nafamostat mesilate instead of heparin to prevent bleeding and to maintain electrolyte balance, and red cell concentrates and erythropoietin were administered for the improvement of anemia. A triple lumen catheter was inserted in the right internal jugular vein in preparation for emergency continuous hemodiafiltration to maintain homeostasis of circulatory dynamics. Surgery was completed without incident and the tumor was resected totally. During surgery, cerebral edema was well controlled by hyperventilation and a slightly upturned head position. Histopathological examination of the specimen confirmed atypical meningioma. Continuous hemodiafiltration was performed for 24 hours after surgery, and hemodialysis was initiated on the third day after surgery. The postoperative course was uneventful. Three weeks after surgery, the patient was discharged with no neurological deficit and resumed his daily life on maintenance hemodialysis.

Progressive Multifocal Leukoencephalopathy in a Patient with Multifocal Neurological Manifestations Caused by Solitary Brainstem Involvement.

A Japanese man in his 60s on medication for chronic lymphocytic leukemia presented with progressive, multifocal neurological manifestations. Magnetic resonance imaging showed a small, solitary region of brainstem involvement. Sensitive real-time polymerase chain reaction testing detected a small amount of JC virus (JCV) DNA (170 copies/mL) with pathogenic mutation in cerebrospinal fluid. We diagnosed the patient with progressive multifocal leukoencephalopathy (PML). The small PML lesion may have caused multifocal neurological symptoms because of its focal brainstem involvement. This case contributes to knowledge regarding the diagnosis and treatment of brainstem PML in the context of hematologic malignancies and other underlying diseases.

Potential factors for and the prognostic impact of ascites after allogeneic hematopoietic stem cell transplantation.

Ascites is sometimes detected after allogeneic hematopoietic stem cell transplantation (allo-HSCT); however, since limited information is currently available, its clinical meaning remains unclear. Therefore, we herein examined potential factors for and the impact of ascites on the prognosis of patients after allo-HSCT at our institutes. Fifty-eight patients developed ascites within 90 days of allo-HSCT (small in 34 (16%), moderate-large in 24 (11%)). A multivariate analysis identified veno-occlusive disease/sinusoidal obstruction syndrome (p = 0.01) and myeloablative conditioning (p = 0.01) as significant potential factors for the development of small ascites. Thrombotic microangiopathy (TMA) (p < 0.01) was a significant potential factor for moderate-large ascites. The incidence of both small and moderate-large ascites correlated with lower overall survival (p = 0.03 for small ascites and p < 0.01 for moderate-large ascites) and higher non-relapse mortality rates (p = 0.03 for small ascites and p < 0.01 for moderate-large ascites). Lower OS and higher NRM rates correlated with the incidence of both small and moderate-large ascites. Further investigation is warranted to establish whether the clinical sign of ascites improves the diagnostic quality of TMA in a large-scale study.

Quantifying the effectiveness of rehabilitation for post-radical prostatectomy urinary incontinence: Novel pelvic floor function assessment using M-mode ultrasonography.

Introduction: This study aimed to develop a method for evaluating pelvic floor function using M-mode ultrasound imaging and quantify the effectiveness of urinary incontinence rehabilitation. Case presentation: Eight participants aged 66-76 years, with urinary incontinence following radical prostatectomy, underwent pelvic floor muscle training. Using M-mode ultrasound, we compared bladder base elevation time, length, and speed during pelvic floor muscle contraction. The results showed that four patients recovered urinary continence. Four patients displayed a 38.4%-80.1% reduction in urinary incontinence volume. Bladder elevation time was significantly reduced in all patients. Moreover, elevation speed increased significantly. Bladder base elevation time was 0.1 s in all patients in the acquired urinary continence group. Conclusions: Reducing bladder base elevation time to <0.2 s might be essential to achieve urinary continence. An elevation time of ≥0.3 s indicated significant pelvic floor muscle dysfunction.

CD21lo B Cells Could Be a Potential Predictor of Immune-Related Adverse Events in Renal Cell Carcinoma.

Immune checkpoint inhibitor (ICI) therapy increases the risk of immune-related adverse events (irAEs). In particular, combination checkpoint blockade (CCB) targeting inhibitory CTLA-4 and PD-1 receptors could lead to irAEs at a higher rate than ICI monotherapy. Management of irAEs is important while using ICIs. However, there are no reliable biomarkers for predicting irAEs. The aim of this study was to elucidate early B cell changes after CCB therapy in patients with renal cell carcinoma (RCC) and verify whether B cells can be a predictor of irAEs. This prospective cohort study was conducted with 23 Japanese patients with metastatic RCC. An increase in the proportion of CD21lo B cells and CD21lo memory B cells was confirmed following CCB therapy. Although there were no differences in clinical outcomes between irAE and no-irAE groups, the proportion of CD21lo B cells at baseline was lower in the irAE group, with a significant increase after the first cycle of CCB therapy. Further analysis revealed a moderate correlation between irAEs and CD21lo B cell levels at baseline (area under the curve: 0.83, cut-off: 3.13%, sensitivity: 92.3, specificity: 70.0). This finding indicates that patients with low baseline CD21lo B cell levels warrant closer monitoring for irAEs. The clinical registration number by the Certified Review Board of Ehime University is No. 1902011.