Nephrotoxicity of Cancer Immunotherapies: Past, Present and Future

Diagnosing acute interstitial nephritis: considerations for clinicians

Acute interstitial nephritis (AIN) is a common cause of acute kidney injury (AKI), particularly in hospitalized patients. It can be difficult for clinicians to differentiate between AIN and other common causes of AKI, most notably acute tubular necrosis (ATN) and prerenal injury. Clinicians often struggle with the clinical history and laboratory data available to definitively diagnose AIN. Sometimes they diagnose ATN or AIN based on these flawed data. Thus it is important that clinicians be familiar with the utility of commonly ordered tests used to aid in the diagnosis. Unfortunately, no single test performs particularly well on its own, and until a biomarker is rigorously shown to be diagnostic of AIN, most patients require a kidney biopsy to definitively establish the diagnosis and direct further management.

Anti-PD-1 Immunotherapy May Induce Interstitial Nephritis With Increased Tubular Epithelial Expression of PD-L1

Introduction

Novel anticancer therapies include anti–programmed cell death protein-1 (PD-1) and anti–programmed death ligand-1 (PD-L1) drugs. These novel medications have side effects in different organs, including the kidney. The most common adverse effect in the kidney is acute interstitial nephritis (AIN). No diagnostic criteria are available to distinguish AIN associated with anti–PD-1 therapy from other AINs.

Methods

Kidney biopsy specimens from patients on anti–PD-1 therapy were stained with antibodies to PD-1 and PD-L1. Herein we report morphologic and immunohistochemical findings in 15 patients who received anti–PD-1 therapy and developed acute kidney injury requiring a kidney biopsy.

Results

Among these patients, 9 had AIN and 6 had no AIN but showed acute tubular necrosis (ATN). Immunohistochemistry with antibodies to PD-1 and PD-L1 was performed on all of these biopsy specimens and on 9 randomly selected biopsy specimens with AIN from patients who did not receive anti–PD-1 medications, as well as 9 patients with lupus nephritis and active-appearing interstitial inflammation. There was weak staining for PD-1 in T cells in all patients with AIN and lupus; however, tubular epithelial cell membrane staining for PD-L1 was seen only in patients with anti–PD-1 therapy−associated AIN, and not in patients with anti–PD-1 therapy−associated ATN, and not in those with AIN secondary to other medications, or patients with lupus nephritis.

Conclusion

We propose that immunohistochemistry with PD-L1 could be a useful tool to differentiate AIN associated with anti–PD-1 therapy from other AINs.

The nephrotoxicity of new immunotherapies

Introduction: Advanced cancers that did not respond to chemotherapy were once a death sentence, but now there are newer therapies utilizing the patient's own immune system to fight cancer that are proving effective in chemotherapy-refractory malignancies. However, this success against cancer cells may be accompanied by immune-related adverse events that can affect the kidneys. Areas covered: Using Medline and Scopus, we compiled all publications through February 2019 that pertained to immune checkpoint inhibitors (ICPIs) and chimeric antigen receptor T-cells (CAR T-cells).  The focus of this review is the discussion of these new cancer therapies, with attention to the reported kidney-related adverse effects.. Expert opinion: Autoimmunity is repressed by molecular pathways that inhibit T-cell activation against selected antigens. These self-protective mechanisms have been appropriated by tumor cells as a means of evading immune detection and destruction. New immunotherapies such as immune checkpoint inhibitors and chimeric antigen receptor T-cell therapy incite an aggressive immune response directed against tumor cells. This unrestrained activation of the immune system may result in kidney injury via multiple mechanisms.

A Novel Multi-Biomarker Assay for Non-Invasive Quantitative Monitoring of Kidney Injury

The current standard of care measures for kidney function, proteinuria, and serum creatinine (SCr) are poor predictors of early-stage kidney disease. Measures that can detect chronic kidney disease in its earlier stages are needed to enable therapeutic intervention and reduce adverse outcomes of chronic kidney disease. We have developed the Kidney Injury Test (KIT) and a novel KIT Score based on the composite measurement and validation of multiple biomarkers across a unique set of 397 urine samples. The test is performed on urine samples that require no processing at the site of collection and without target sequencing or amplification. We sought to verify that the pre-defined KIT test, KIT Score, and clinical thresholds correlate with established chronic kidney disease (CKD) and may provide predictive information on early kidney injury status above and beyond proteinuria and renal function measurements alone. Statistical analyses across six DNA, protein, and metabolite markers were performed on a subset of residual spot urine samples with CKD that met assay performance quality controls from patients attending the clinical labs at the University of California, San Francisco (UCSF) as part of an ongoing IRB-approved prospective study. Inclusion criteria included selection of patients with confirmed CKD and normal healthy controls; exclusion criteria included incomplete or missing information for sample classification, logistical delays in transport/processing of urine samples or low sample volume, and acute kidney injury. Multivariate logistic regression of kidney injury status and likelihood ratio statistics were used to assess the contribution of the KIT Score for prediction of kidney injury status and stage of CKD as well as assess the potential contribution of the KIT Score for detection of early-stage CKD above and beyond traditional measures of renal function. Urine samples were processed by a proprietary immunoprobe for measuring cell-free DNA (cfDNA), methylated cfDNA, clusterin, CXCL10, total protein, and creatinine. The KIT Score and stratified KIT Score Risk Group (high versus low) had a sensitivity and specificity for detection of kidney injury status (healthy or CKD) of 97.3% (95% CI: 94.6-99.3%) and 94.1% (95% CI: 82.3-100%). In addition, in patients with normal renal function (estimated glomerular filtration rate (eGFR) ≥ 90), the KIT Score clearly identifies those with predisposing risk factors for CKD, which could not be detected by eGFR or proteinuria (p < 0.001). The KIT Score uncovers a burden of kidney injury that may yet be incompletely recognized, opening the door for earlier detection, intervention and preservation of renal function.

Onco-Nephrology: Cancer, chemotherapy and kidney

Chronic kidney disease (CKD), cancer and haematological diseases share areas of reciprocal influence. Cancer can affect the kidney either as glomerular lesions or as a result of the toxic effects of medication or radiation with acute (thrombotic microangiopathy, acute kidney injury, interstitial nephropathies among others) or chronic processes (worsening of CKD after nephrectomy due to renal cancer, interstitial fibrosis, hydroelectrolytic disorders). On the other hand, patients who require renal replacement therapy with dialysis and particularly with kidney transplantation are at high risk of onset of cancer due to the immunosuppression situation that they generate. In addition to conventional chemotherapy, innovative treatments have been developed: target agents against growth factors and their receptor; anti-angiogenic drugs; immunoregulatory proteins; cell cycle regulators; and enzyme inhibitors. Other immunotherapeutic approaches have also been developed, such as vaccines, adoptive cell therapy (CAR T cells) or development of antibodies. All these therapeutic advances will improve the outcomes against cancer and haematological diseases, but they are not free from secondary renal problems. Onco-Nephrology is already an important area for the Spanish Society of Nephrology with a large number of inter-consultations. Nephrologists need a better understanding of rapidly evolving areas of cancer biology and its treatment in order to become valued members of the cancer care team and to provide the best nephrology care possible.