We speculated the renal pathology of our patient was minimal switch disease as all the reported instances in pembrolizumab-associated nephrotic syndrome had exhibited minimal switch disease [3C6]. was minimal MCL-1/BCL-2-IN-4 switch disease. Our case shows for the first time that renal function could be reversible with prednisolone in pembrolizumab-associated nephrotic syndrome with severe AKI actually after progression of renal failure which demands dialysis. white blood cell count, hemoglobin, platelet, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, total protein, albumin, total cholesterol, blood urea nitrogen, creatinine, uric acid, inorganic phosphate, C-reactive protein, glycosylated hemoglobin, blood sugar, match component 3, match component 4, match activities, immunoglobulin, antinuclear antibodies, anti-DNA antibody, reddish blood MCL-1/BCL-2-IN-4 cell, N-acetyl–D-glucosaminidase, hSNFS -2 microglobulin, fraction excretion Open in a separate windowpane Fig. 1 Clinical program during hospitalization. Serum creatinine level and 24-h urine volume are demonstrated in a solid collection and dotted collection, respectively. The gray/white colored package indicates intravenous/oral administration of the medicines. Hemodialysis was withdrawn, because urine output was dramatically improved Open in a separate windowpane Fig. 2 Switch of proteinuria after discharge. The amount of proteinuria and serum creatinine (SCr) level are demonstrated in a solid collection and dotted collection, respectively Conversation Pembrolizumab is definitely a humanized, monoclonal IgG4-kappa isotype antibody against PD-1 which gets rid of the checkpoints from your immune system and activates T cells, and thus, it is referred to as immune checkpoint inhibitor. Currently, two types of immune checkpoint inhibitors are available. The first is PD-1-obstructing antibodies including pembrolizumab/nivolumab, and another is definitely Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4)-obstructing antibodies such as ipilimumab/tremelimumab. Immune-related toxicities such as colitis, dermatitis, pneumonitis, hepatitis, and thyroiditis are common with these medicines [7, 8]. On the other hand, the incidence of the renal adverse events by immune checkpoint inhibitors was considered to be low . However, recent reports exposed that the incidence was not rare . Main pathology by these medicines was acute tubulointerstitial lesions , whereas additional pathologies were also reported, including minimal switch disease, IgA nephropathy, lupus nephropathy, thrombotic microangiopathy, and pauci-immune glomerulonephritis [3C6, 10C12]. In our case, we could not perform renal biopsy, because he was treated with direct oral anticoagulant against venous thrombosis. We speculated the renal pathology of our patient MCL-1/BCL-2-IN-4 was minimal switch disease as all the reported instances in pembrolizumab-associated nephrotic syndrome experienced exhibited minimal switch disease [3C6]. In addition, the clinical course of the patient (acute onset of nephrotic syndrome with AKI and response to steroid therapy) was consistent with minimal switch disease. In the present case, urinary NAG and 2-microglobulin at the time of onset showed high ideals, which might derive from tubular injury as others have reported . However, it was hard to distinguish whether the cause of the elevation of these parameters was due to AKI or tubular injury by pembrolizumab. The onset of nephrotic syndrome with AKI in our case occurred after the seventh course of pembrolizumab, which means 5?weeks after pembrolizumab initiation. Median time to the onset of renal adverse event by immune checkpoint inhibitors was highly variable, ranging from 6 to 30?weeks . Concerning PD-1 inhibitors, median time in nivolumab was from 6 to 10?weeks [14, 15]; on the other hand, that in pembrolizumab has not been reported yet. The timing of pembrolizumab-associated nephrotic syndrome with AKI was reported to occur after the second-dose administration [3C6]. An atypical case of patient with slight AKI and nephrotic range of proteinuria without decrease of serum albumin was reported . The onset of renal adverse event in the case occurred 18?months after pembrolizumab initiation. The reason behind the relatively late onset of nephrotic syndrome with AKI in our case is not clear. Cancer-induced minimal switch disease might be considered as an etiology of nephrotic syndrome. Minimal switch disease in association with cancers including lung malignancy has been reported . The degree of proteinuria was correlated with tumor progression/regression in the instances, suggesting that factors released from malignancy cells induce minimal switch disease . However, the size of tumor in the current case was regressed before fifth course of pembrolizumab administration, and had not been progressed again until discharge, denying the possibility of minimal switch disease induced by malignancy. Erythematous rash on the lower extremities was preceded nephrotic syndrome in this case. Erythematous rash within the trunk or extremities is one MCL-1/BCL-2-IN-4 MCL-1/BCL-2-IN-4 of the typical skin adverse effects of immune checkpoint inhibitors . It has been reported the.