Immunological mechanisms underlying clinical phenotypes and noninvasive diagnosis of immune checkpoint inhibitor-induced kidney disease.

Immune checkpoint inhibitors (ICIs) have become a mainstay of cancer therapy, with over 80 FDA-approved indications. Used in a variety of settings and in combination with each other and with traditional chemotherapies, the hyperactive immune response induced by ICIs can often lead to immune-related adverse events in bystander normal tissues such as the kidneys, lungs, and the heart. In the kidneys, this immune-related adverse event manifests as acute interstitial nephritis (ICI-AIN). In the era of widespread ICI use, it becomes vital to understand the clinical manifestations of ICI-AIN and the importance of prompt diagnosis and management of these complications. In this review, we delve into the clinical phenotypes of ICI-AIN and how they differ from traditional drug-induced AIN. We also detail what is known about the mechanistic underpinnings of ICI-AIN and the important diagnostic and therapeutic implications behind harnessing those mechanisms to further our understanding of these events and to formulate effective treatment plans to manage ICI-AIN.

Clinical features of acute kidney injury in patients receiving dabrafenib and trametinib.

BACKGROUND: Our objective was to characterize the incidence, risk factors and clinical features of acute kidney injury (AKI) in patients receiving dabrafenib and trametinib. METHODS: We performed a retrospective cohort study examining the kidney outcomes of patients in a large healthcare system who received dabrafenib/trametinib between 2010 and 2019. The primary outcome was AKI, defined as a 1.5-fold increase in serum creatinine from baseline within a 12-month study period. AKI severity and etiology was determined for each case by chart review. Logistic regression was used to evaluate baseline predictors of AKI. RESULTS: A total of 199 patients who received dabrafenib in our healthcare system from 2010 to 2019 were included in the analysis. Forty-two patients (21%) experienced AKI within 12 months; 10 patients (5% of the total cohort, 24% of AKI patients) experienced AKI occurring during a dabrafenib/trametinib-induced febrile syndrome characterized by fever, chills, gastrointestinal symptoms and elevated liver enzymes. Preexisting liver disease was the only significant predictor of AKI in the cohort. One patient had biopsy-proven granulomatous acute interstitial nephritis that resolved with corticosteroids. CONCLUSIONS: Oncologists and nephrologists should be aware that AKI is common after dabrafenib/trametinib and a substantial number of cases occur in the setting of treatment-induced pyrexia.

Hyponatremia and other electrolyte abnormalities in patients receiving immune checkpoint inhibitors.

BACKGROUND: Hyponatremia due to endocrinopathies such as adrenal insufficiency and hypothyroidism has been reported in patients receiving immune checkpoint inhibitors (ICIs). We determined the risk and predictors of hyponatremia and other electrolyte abnormalities in a 'real-world' sample of patients receiving ICIs to treat advanced malignancies. METHODS: This was a retrospective observational study of all patients who received ICIs from a single cancer center between 2011 and 2018. Patients were followed for 12 months after initiation of ICIs or until death. Common Terminology for Cancer Adverse Events version 5.0 criteria were used to grade the severity of hyponatremia and other electrolyte abnormalities. The predictors of severe (Grade 3 or 4) hyponatremia were determined using a multivariable logistic regression model. The etiology of Grade 3 or 4 hyponatremia was determined by chart review. RESULTS: A total of 2458 patients were included. Their average age was 64 years [standard deviation (SD) 13], 58% were male and 90% were white. In the first year after starting ICIs, 62% experienced hyponatremia (sodium <134 mEq/L) and 136 (6%) experienced severe hyponatremia (<124 mEq/L). Severe hyponatremia occurred on average 164 days (SD 100) after drug initiation. Only nine cases of severe hyponatremia were due to endocrinopathies (0.3% overall incidence). Risk factors for severe hyponatremia included ipilimumab (a cytotoxic T lymphocyte antigen-4 inhibitor) use, diuretic use and non-White race. Other severe electrolyte abnormalities were also commonly observed: severe hypokalemia (potassium <3.0 mEq/L) occurred in 6%, severe hyperkalemia (potassium ≥6.1 mEq/L) occurred in 0.6%, severe hypophosphatemia (phosphorus <2 mg/dL) occurred in 17% and severe hypocalcemia (corrected calcium <7.0 mg/dL) occurred in 0.2%. CONCLUSIONS: Hyponatremia is common in cancer patients receiving ICIs. However, endocrinopathies are an uncommon cause of severe hyponatremia.

Acute Kidney Injury and Electrolyte Abnormalities After Chimeric Antigen Receptor T-Cell (CAR-T) Therapy for Diffuse Large B-Cell Lymphoma.

RATIONALE & OBJECTIVE: Cytokine release syndrome is a well-known complication of chimeric antigen receptor T-cell (CAR-T) therapy and can lead to multiorgan dysfunction. However, the nephrotoxicity of CAR-T therapy is unknown. We aimed to characterize the occurrence, cause, and outcomes of acute kidney injury (AKI), along with the occurrence of electrolyte abnormalities, among adults with diffuse large B-cell lymphoma receiving CAR-T therapy. STUDY DESIGN: Case series. SETTING & PARTICIPANTS: We reviewed the course of 78 adults receiving CAR-T therapy with axicabtagene ciloleucel or tisagenlecleucel at 2 major cancer centers between October 2017 and February 2019. Baseline demographics, comorbid conditions, medications, and laboratory values were obtained from electronic health records. AKI was defined using KDIGO (Kidney Disease: Improving Global Outcomes) criteria. The cause, clinical course, and outcome of AKI events and electrolyte abnormalities in the first 30 days after CAR-T infusion were characterized using data contained in electronic health records. RESULTS: Among 78 patients receiving CAR-T therapy, cytokine release syndrome occurred in 85%, of whom 62% were treated with tocilizumab. AKI occurred in 15 patients (19%): 8 had decreased kidney perfusion, 6 developed acute tubular necrosis, and 1 patient had urinary obstruction related to disease progression. Those with acute tubular necrosis and obstruction had the longest lengths of stay and highest 60-day mortality. Electrolyte abnormalities were common; hypophosphatemia, hypokalemia, and hyponatremia occurred in 75%, 56%, and 51% of patients, respectively. LIMITATIONS: Small sample size; AKI adjudicated by retrospective chart review; lack of biopsy data. CONCLUSIONS: In this case series of patients with diffuse large B-cell lymphoma receiving CAR-T therapy, AKI and electrolyte abnormalities occurred commonly in the context of cytokine release syndrome.

Diagnosis and Management of Immune Checkpoint Inhibitor-Associated Renal Toxicity: Illustrative Case and Review.

Immune checkpoint inhibitors (ICIs) are monoclonal antibodies directed at negative regulatory components on T cells, such as cytotoxic T lymphocyte-associated antigen 4, programmed cell death-1 (PD-1), and its ligand, programmed cell death ligand-1. ICIs initate antitumor immunity; however, these agents are associated with immune-related adverse events (irAEs) that may affect a variety of organs. Renal irAEs most commonly present with asymptomatic acute kidney injury (AKI), which is often detected by routine laboratory testing. The severity of AKI associated with irAEs ranges from mild (grade 1-2) to severe (grade 3-4). It is often challenging to diagnose because this group of patients often have multiple reasons to have AKI (dehydration, sepsis, or nephrotoxic medication exposure). We present an illustrative case of a 60-year-old man with metastatic melanoma who presented with AKI during treatment with nivolumab and review the literature to address frequently asked questions concerning the diagnosis and management of renal irAEs in patients with advanced cancer. Importantly, most patients will recover completely, and some may tolerate a rechallenge of ICI therapy, with prompt and effective treatment. KEY POINTS: Renal immune-related adverse events (irAEs) are less frequently reported than other irAEs; however, it is possible that available data underestimate their true incidence because of missed diagnoses and under-reporting. Although severe renal irAEs are more easily detected, smaller rises in creatinine may not be appreciated or may be attributed to other causes, because the differential diagnosis of acute kidney injury (AKI) in patients with cancer is broad.Baseline creatinine should be established prior to beginning immune checkpoint inhibitorss (ICIs), and it should be monitored with every cycle. If a patient develops AKI, the ICI should be held while the evaluation is pursued. A thorough workup of suspected renal irAEs must exclude other potential causes of AKI such as infection, dehydration, urinary tract obstruction, and nephrotoxin exposure.Acute kidney injury after ICI therapy does not appear to be more common in patients with baseline estimated glomerular filtration rate <60 mL per min per 1.73 m. One particular concern, however, is that those with baseline renal disease have less "renal reserve," and repeated AKI events may push a patient closer to end-stage renal disease. Thus, clinicians must exert caution when rechallenging patients with pre-existing renal disease with ICI therapy in the event of a prior AKI from ICI-related allergic interstitial nephritis.

Revisiting therapeutic options for calciphylaxis.

PURPOSE OF REVIEW: Calciphylaxis is a disorder of cutaneous microvascular calcification and thrombosis leading to chronic, excruciatingly painful, progressive wounds with a high risk of sepsis and death. The diagnosis and treatment of calciphylaxis presents significant challenges. A poorly understood disease, the management of calciphylaxis has mostly been restricted to wound management and a few novel therapies. Data from patient registries and new studies on causal pathways is stimulating the development of pathogenesis-based medical therapies. RECENT FINDINGS: Much needed clinical trials are now underway to examine the safety and efficacy of sodium thiosulfate and other therapeutics for the indication of calciphylaxis. There is emerging data suggesting a potential role of therapeutic anticoagulation in these patients. There has also been a renewed emphasis on patient-oriented outcomes, such as improvement of pain scores and quality-of-life indices. SUMMARY: This review highlights ongoing clinical trials studying therapeutic options in calciphylaxis and emphasizes the causal pathways that led to the development of such therapies.

Pathophysiology and Management of Hyperammonemia in Organ Transplant Patients.

Neurologic complications are common after solid-organ transplantation, occurring in one-third of patients. Immunosuppression-related neurotoxicity (involving calcineurin inhibitors and corticosteroids), opportunistic central nervous system infections, seizures, and delirium are some of the causes of neurologic symptoms following solid-organ transplantation. An uncommon often missed complication posttransplantation involves buildup of ammonia levels that can lead to rapid clinical deterioration even when treated. Ammonia levels are not routinely checked due to the myriad of other explanations for encephalopathy in a transplant recipient. A treatment of choice for severe hyperammonemia involves renal replacement therapy (RRT), but there are no guidelines on the mode or parameters of RRT for reducing ammonia levels. Hyperammonemia in a transplant recipient poses specific challenges beyond the actual condition because the treatment (RRT) involves significant hemodynamic fluctuations that may affect the graft. In this review, we describe a patient with posttransplantation hyperammonemia and discuss the pathways of ammonia metabolism, potential factors underlying the development of hyperammonemia posttransplantation, and choice of appropriate therapeutic options in these patients.

Minimal Change Disease.

Minimal change disease represents a common cause of nephrotic syndrome in both pediatric and adult patients. Although much remains to be discovered, there have been significant recent advancements in our understanding of the pathophysiology of minimal change disease, including the discovery of antinephrin antibodies as a marker for diagnosis of disease. Here we will review what is known about the pathophysiology, treatment, and prognosis of minimal change disease and the differences between pediatric and adult patients. Recent advances in our understanding of the mechanisms of disease will be noted. We will discuss how this may change the treatment of minimal change disease going forward and what remains to be studied.

Technological Innovations to Improve Patient Engagement in Nephrology.

Technological innovation has accelerated exponentially over the last 2 decades. From the rise of smartphones and social media in the early 2000s to the mainstream accessibility of artificial intelligence (AI) in 2023, digital advancements have transformed the way we live and work. These innovations have permeated health care, covering a spectrum of applications from virtual reality training platforms to AI-powered clinical decision support tools. In this review, we explore fascinating recent innovations that have and can facilitate patient engagement in nephrology. These include integrated care mobile applications, wearable health monitoring tools, virtual/augmented reality consultation and education platforms, AI-powered appointment booking systems, and patient information tools. We also discuss potential pitfalls in implementation and paradigms to adopt that may protect patients from unintended consequences of being cared for in a digitalized health care system.

Sarcopenia, adiposity and large discordance between cystatin C and creatinine-based estimated glomerular filtration rate in patients with cancer.

BACKGROUND: Creatinine-based estimated glomerular filtration rate (eGFRCRE) may overestimate kidney function in patients with sarcopenia. While cystatin C-based eGFR (eGFRCYS) is less affected by muscle mass, it may underestimate kidney function in patients with obesity. We sought to evaluate the relationship between body composition defined by computed tomography (CT) scans and discordance between creatinine, eGFRCRE and eGFRCYS in adult patients with cancer. METHODS: This study is a cross-sectional study of consecutive adults with cancer with an abdominal CT scan performed within 90 days of simultaneous eGFRCRE and eGFRCYS measurements between May 2010 and January 2022. Muscle and adipose tissue cross-sectional areas were measured at the level of the third lumbar vertebral body using a validated deep-learning pipeline. CT-defined sarcopenia was defined using independent sex-specific cut-offs for skeletal muscle index (<39 cm2/m2 for women and <55 cm2/m2 for men). High adiposity was defined as the highest sex-specific quartile of the total (visceral plus subcutaneous) adiposity index in the cohort. The primary outcome was eGFR discordance, defined by eGFRCYS > 30% lower than eGFRCRE; the secondary outcome was eGFRCYS > 50% lower than eGFRCRE. The odds of eGFR discordance were estimated using multivariable logistic regression modelling. Unadjusted spline regression was used to evaluate the relationship between skeletal muscle index and the difference between eGFRCYS and eGFRCRE. RESULTS: Of the 545 included patients (mean age 63 ± 14 years, 300 [55%] females, 440 [80.7%] non-Hispanic white), 320 (58.7%) met the criteria for CT-defined sarcopenia, and 136 (25%) had high adiposity. A total of 259 patients (48%) had >30% eGFR discordance, and 122 (22.4%) had >50% eGFR discordance. After adjustment for potential confounders, CT-defined sarcopenia and high adiposity were both associated with >30% eGFR discordance (adjusted odds ratio [aOR] 1.90, 95% confidence interval [CI] 1.12-3.24; aOR 2.01, 95% CI 1.15-3.52, respectively) and >50% eGFR discordance (aOR 2.34, 95% CI 1.21-4.51; aOR 2.23, 95% CI 1.19-4.17, respectively). A spline model demonstrated that as skeletal muscle index decreases, the predicted difference between eGFRCRE and eGFRCYS widens considerably. CONCLUSIONS: CT-defined sarcopenia and high adiposity are both independently associated with large eGFR discordance. Incorporating valuable information from body composition analysis derived from CT scans performed as a part of routine cancer care can impact the interpretation of GFR estimates.

Medication-related adverse events in patients with cancer and discrepancies in cystatin C- versus creatinine-based eGFR.

Background: Creatinine-based estimated glomerular filtration rate (eGFRCRE) may overestimate kidney function in patients with cancer. Cystatin C-based eGFR (eGFRCYS) is an alternative marker of kidney function. We investigated whether patients with an eGFR discrepancy, defined as eGFRCYS >30% lower than the concurrent eGFRCRE, had an increased risk of adverse events resulting from renally-cleared medications. Patients and Methods: We conducted a cohort study of adult patients with cancer who had serum creatinine and cystatin C measured on the same day between May 2010 and January 2022 at two academic cancer centers in Boston, MA. The primary outcome was the incidence of each of the following medication-related adverse events: 1) supratherapeutic vancomycin levels (>30µg/mL); 2) trimethoprim-sulfamethoxazole-related hyperkalemia (>5.5mEq/L); 3) baclofen-induced neurotoxicity; and 4) supratherapeutic digoxin levels (>2.0ng/mL). Results: 1988 patients with cancer had simultaneous eGFRCYS and eGFRCRE. The mean age was 66 years (SD±14), 965 (49%) were female, and 1555 (78%) were non-Hispanic white. eGFR discrepancy occurred in 579 patients (29%). Patients with eGFR discrepancy were more likely to experience medication-related adverse events compared to those without eGFR discrepancy: vancomycin levels >30µg/mL (24% vs. 10%, p=0.004), trimethoprim- sulfamethoxazole-related hyperkalemia (24% vs. 12%, p=0.013), baclofen-induced neurotoxicity (25% vs. 0%, p=0.13), and supratherapeutic digoxin levels (38% vs. 0%, p=0.03). The adjusted OR for vancomycin levels >30µg/mL was 2.30 (95% CI 1.05 - 5.51, p = 0.047). Conclusion: Among patients with cancer with simultaneous assessment of eGFRCYS and eGFRCRE, medication-related adverse events occur more commonly in those with eGFR discrepancy. These findings underscore the importance of accurate assessment of kidney function and appropriate dosing of renally-cleared medications in patients with cancer.

Medication-Related Adverse Events and Discordancies in Cystatin C-Based vs Serum Creatinine-Based Estimated Glomerular Filtration Rate in Patients With Cancer.

Importance: Serum creatinine-based estimated glomerular filtration rate (eGFRcr) may overestimate the glomerular filtration rate (GFR) in patients with cancer. Cystatin C-based eGFR (eGFRcys) is an alternative marker of GFR. Objective: To determine whether the therapeutic drug levels and adverse events (AEs) associated with renally cleared medications were higher in patients with cancer whose eGFRcys was more than 30% lower than their eGFRcr. Design, Setting, and Participants: This cohort study analyzed adult patients with cancer at 2 major academic cancer centers in Boston, Massachusetts. These patients had their creatinine and cystatin C measured on the same day between May 2010 and January 2022. The date of the first simultaneous eGFRcr and eGFRcys measurement was considered to be the baseline date. Exposure: The primary exposure was eGFR discordance, defined as an eGFRcys that was more than 30% lower than the eGFRcr. Main Outcomes and Measures: The primary outcome was risk of the following medication-related AEs within 90 days of the baseline date: (1) supratherapeutic vancomycin trough level greater than 30 µg/mL, (2) trimethoprim-sulfamethoxazole-related hyperkalemia (>5.5 mEq/L), (3) baclofen toxic effect, and (4) supratherapeutic digoxin level (>2.0 ng/mL). For the secondary outcome, a multivariable Cox proportional hazards regression model was used to compare 30-day survival of those with vs without eGFR discordance. Results: A total of 1869 adult patients with cancer (mean [SD] age, 66 [14] years; 948 males [51%]) had simultaneous eGFRcys and eGFRcr measurement. There were 543 patients (29%) with an eGFRcys that was more than 30% lower than their eGFRcr. Patients with an eGFRcys that was more than 30% lower than their eGFRcr were more likely to experience medication-related AEs compared with patients with concordant eGFRs (defined as eGFRcys within 30% of eGFRcr), including vancomycin levels greater than 30 µg/mL (43 of 179 [24%] vs 7 of 77 [9%]; P = .01), trimethoprim-sulfamethoxazole-related hyperkalemia (29 of 129 [22%] vs 11 of 92 [12%]; P = .07), baclofen toxic effects (5 of 19 [26%] vs 0 of 11; P = .19), and supratherapeutic digoxin levels (7 of 24 [29%] vs 0 of 10; P = .08). The adjusted odds ratio for vancomycin levels more than 30 µg/mL was 2.59 (95% CI, 1.08-7.03; P = .04). Patients with an eGFRcys more than 30% lower than their eGFRcr had an increased 30-day mortality (adjusted hazard ratio, 1.98; 95% CI, 1.26-3.11; P = .003). Conclusions and relevance: Results of this study suggest that among patients with cancer with simultaneous assessment of eGFRcys and eGFRcr, supratherapeutic drug levels and medication-related AEs occurred more commonly in those with an eGFRcys more than 30% lower than their eGFRcr. Future prospective studies are needed to improve and personalize GFR estimation and medication dosing in patients with cancer.