Malignancy in Membranous Nephropathy: Evaluation of Incidence

Neural epidermal growth factor-like 1 protein (NELL1)-associated membranous nephropathy with heterogeneous underlying diseases: a case report

Neural epidermal growth factor-like 1 protein (NELL1) is a target antigen of membranous nephropathy (MN). NELL1-associated MN (NELL1-MN) was originally described as a primary form but has subsequently been associated with other diseases, including malignancies, pre-exposure to certain drugs, hepatitis B virus (HBV) and hepatitis C virus (HCV) infections, and rheumatoid arthritis (RA). We present a case of a 78-year-old woman with long-standing RA who developed persistent proteinuria and was diagnosed with MN. Evaluation of the underlying cause revealed chronic active HCV infection and past HBV infection. The underlying cause was less likely to be drug-related; however, there was no evidence of malignancy. The patient was diagnosed with HCV-associated MN. At 4 years after the diagnosis of MN, the patient died of breast cancer with multiple metastases. Subsequent immunohistological analysis revealed that she had NELL1-MN, and her breast cancer tissue stained positive for NELL1. Our case illustrates the difficulty in establishing the underlying cause of NELL1-MN, even after diagnosis. However, the incidence of malignancies, particularly breast and prostate cancers, is higher in NELL1-MN than in MN with other target antigens. Therefore, malignancies are considered a priority for investigation because of their frequency and prognosis among patients with NELL1-MN.

Effect of rituximab in patients with PLA2R-associated membranous nephropathy and malignancy

INTRODUCTION

Phospholipase A2 receptor (PLA2R)-associated membranous nephropathy (MN) is a common cause of nephrotic syndrome in nondiabetic adults who are also within the common age group for malignancy. How to treat patients with PLA2R-associated MN and malignancy effectively and safely still requires careful consideration. The aim of our study was to examine the outcomes and safety of rituximab (RTX) in these patients.

METHODS

Retrospective analysis of clinical data was performed on 15 patients with PLA2R-associated MN and malignancy. Patients were followed every 1-3 months for a minimum of 24 months. Clinical data were collected, including CD19+ B cells, anti-PLA2R antibodies, 24-hour urinary protein, serum albumin, and serum creatinine. The percentage of patients who achieved clinical remission and immunological remission was also measured.

RESULTS

Among these 15 patients, 14 patients with solid tumors received treatment for malignant diseases with complete resection. One patient received chemotherapy for chronic myeloid leukemia, and achieved complete remission 36 months before the diagnosis of MN. There were 6 (40.00 %) patients who achieved complete remission and 14 (93.33 %) patients who achieved complete or partial remission at the last visit after RTX treatment. At the last visit, patients were clinically improved, as evidenced by significant improvements in anti-PLA2R antibody titer [2.00 (2.00, 2.00) vs 35.25 (11.18, 91.58) RU/ml, P = 0.002], 24-hour urine protein [0.39 (0.11, 2.28) vs 9.22 (4.47, 14.73) g/d, P = 0.001], and serum albumin [38.15 (34.80, 43.20) vs 23.70 (18.70, 25.70) g/L, P = 0.001]. During the follow-up, the renal function of those patients remained stable. Recurrence of malignant tumors or the occurrence of new tumor events were not observed.

CONCLUSION

In this single-center retrospective study with a small sample size, RTX therapy might be an effective and safe treatment in patients with PLA2R-associated MN and malignancy.

Case Report: Successful treatment of late-onset immune checkpoint inhibitor-associated membranous nephropathy in a patient with advanced renal cell carcinoma

Background

Diagnosing immune checkpoint inhibitor (ICI)-associated nephritis can be challenging since it is a rare complication of therapy, associated with a spectrum of immune-mediated pathologies, and can present months after ICI therapy discontinuation (i.e., late-onset). ICIs are increasingly administered in combination with other cancer therapies with associated nephrotoxicity, further obfuscating the diagnosis of ICI-associated nephritis. In this report, we describe the first suspected case of late-onset ICI-associated membranous nephropathy (MN) in a patient with metastatic clear cell renal cell carcinoma (RCC) who had discontinued ICI therapy 6 months prior to presentation. Prompt recognition of the suspected late-onset immune-related adverse event (irAE) resulted in the successful treatment of MN and continuation of RCC therapy.

Case presentation

A 57-year-old man with metastatic clear cell RCC was responsive to third-line RCC therapy with lenvatinib (oral TKI) and everolimus (oral mTOR inhibitor) when he presented with nephrotic range proteinuria and acute kidney injury (AKI). His kidney biopsy revealed probable secondary MN with subendothelial and mesangial immune complex deposits and negative staining for both phospholipase A2 receptor (PLA2R) and thrombospondin type-1 domain-containing 7A (THSD7A). While a diagnosis of paraneoplastic MN could not be excluded, the patient was responding to cancer therapy and had tumor regression. However, 6 months prior to presentation, the patient had received pembrolizumab, an ICI, with his first-line RCC treatment. Due to concern that the patient may be presenting with late-onset ICI-associated MN, he was effectively treated with rituximab, which allowed for his continued RCC therapy.

Conclusion

This report highlights the first case of suspected late-onset ICI-associated MN and the increasing complexity of recognizing renal irAEs. With the growing indications for the use of ICIs in combination with other cancer therapies, recognizing the various presentations of ICI-immune nephritis can help guide patient management and treatment.

A Target Antigen-Based Approach to the Classification of Membranous Nephropathy

OBJECTIVE

To describe the clinical and pathological phenotype of membranous nephropathy (MN) associated with M-type-phospholipase-A₂-receptor (PLA₂R), thrombospondin-type-1-domain-containing-7A (THSD7A), semaphorin 3B (SEMA3B), neural-epidermal-growth-factor-like-1-protein (NELL-1), protocadherin 7 (PCDH7), exostosin 1/exostosin 2 (EXT1/EXT2) and neural cell adhesion molecule 1 (NCAM-1) as target antigens.

METHODS

A retrospective cohort of 270 adult patients with biopsy-proven MN diagnosed between January 2015 and April 2020 was classified as PLA₂R-, THSD7A-, SEMA3B-, NELL-1-, PCDH7-, EXT1/EXT2-, NCAM-1-associated or septuple-negative MN using serologic tests, immunostaining, and/or mass spectrometry. Clinical, biochemical, pathologic, and follow-up data were systematically abstracted from the medical records, including disease activity of conditions traditionally associated with MN and occurring within 5 years of MN diagnosis.

RESULTS

Patients with PLA₂R-associated MN were predominantly middle-aged white men without associated disease. The presence of associated disease did not affect the clinical and pathologic characteristics of PLA₂R-associated MN, suggesting that they were coincidental rather than causally linked. THSD7A-, NELL-1-, PCDH7-, and NCAM-1-associated MN were rare and SEMA3B-associated MN was not discovered in our cohort. EXT1/EXT2-associated MN was primarily diagnosed in younger women with active systemic autoimmunity. A significant proportion of septuple-negative patients had associated malignancy or systemic autoimmunity.

CONCLUSION

The widely used distinction between primary and secondary MN has limitations. We propose a refined terminology that combines the target antigen and associated disease to better classify MN and guide clinical decision making.

Comparison of cancer prevalence between patients with glomerulonephritis and the general population at the time of kidney biopsy

Glomerulonephritis (GN) has been associated with many solid and hematologic malignancies. However, cancer prevalence at the time of GN diagnosis has been rarely examined. We aimed to evaluate the cancer prevalence in patients with GN at the time of kidney biopsy and to compare the results to those of the general population. A total of 1,155 patients who underwent kidney biopsy between 2003 and 2017 were included. We investigated patients diagnosed with cancer within one month of kidney biopsy. The occurrence of cancer was compared with that of the Korean general population using the observed-to-expected rates (O/E ratio). Twenty-nine patients with GN had cancer. The mean age of patients with and without cancer was 49 and 66 years old, respectively. The proportion of male patients with and without cancer was 49.4% and 58.6%, respectively. The glomerular filtration rate was different between the groups (78.1 ± 37.0, 58.0 ± 43.6 ml/min/1.73 m2, p = 0.006), but the urine protein/creatinine ratio was not (3.21 ± 4.01, 5.38 ± 7.47 g/gCr, p = 0.172). Immunoglobulin A nephropathy (IgAN) was the most common GN (37.9%), followed by membranous GN (13.5%), focal segmental glomerulosclerosis (9.7%), minimal change disease (9.2%), amyloidosis (1.2%). Amyloidosis was the most common GN associated with malignancy (20.7%). In patients with amyloidosis, cancer was observed almost 28 times more than expected and these patients showed higher cancer occurrence than patients with other GN (Relative Risk [RR]: 15.73; 95% confidence interval [CI]: 4.82-51.30; p < 0.01). Cancer occurrence was three times greater in GN patients aged > 50 years compared to the general population (O/E ratio: 3.42; 95% CI: 1.37-5.46; p = 0.027). Patients with GN, especially amyloidosis, have higher risk of cancer than the general population at the time of GN diagnosis. Older age (> 50 years) was one of the major determinants of the presence of cancer in GN patients.

Clinicopathological features in membranous nephropathy with cancer: A retrospective single-center study and literature review

BACKGROUND

Membranous nephropathy is the most common glomerular disease related to malignancy. However, it is difficult to distinguish between true malignancy-related membranous nephropathy and idiopathic membranous nephropathy coincident with cancer. It has been reported that phospholipase A2 receptor (PLA2R) is the first autoantigen involved in idiopathic membranous nephropathy and thrombospondin type-1 domain-containing 7A (THSD7A) may have a close relationship with malignancy-related membranous nephropathy. Therefore, the aim of this study was to compare the clinicopathological characteristics between membranous nephropathy patients with cancer and idiopathic membranous nephropathy patients without cancer to better detect malignancy-related membranous nephropathy, including glomerular PLA2R and THSD7A depositions and their circulating antibodies, together with glomerular IgG4 deposition.

METHODS

Twelve membranous nephropathy patients with cancer and 257 idiopathic membranous nephropathy patients without cancer were included in this study and had been followed up for more than 1 year. The glomerular expression of PLA2R, THSD7A, and IgG4 was analyzed by immunohistochemistry. Circulating anti-PLA2R and anti-THSD7A antibodies were assessed by enzyme-linked immunosorbent assay and indirect immunofluorescence testing, respectively.

RESULTS

Membranous nephropathy patients with cancer were significantly older and had higher serum creatinine and a lower estimated glomerular filtration rate than idiopathic membranous nephropathy patients (P<0.05). The positive rates of glomerular PLA2R and IgG4 depositions and circulating anti-PLA2R antibodies in membranous nephropathy patients with cancer were significantly lower than those in idiopathic membranous nephropathy patients without cancer (P<0.01).

CONCLUSION

The absence of glomerular PLA2R deposition and negative circulating anti-PLA2R antibodies, along with negative glomerular IgG4 staining, may be useful clues to more accurately screen underlying malignancies in membranous nephropathy patients.

Membranous Nephropathy and Anti-Podocytes Antibodies: Implications for the Diagnostic Workup and Disease Management

The discovery of circulating antibodies specific for native podocyte antigens has transformed the diagnostic workup and greatly improved management of idiopathic membranous nephropathy (iMN). In addition, their identification has clearly characterized iMN as a largely autoimmune disorder. Anti-PLA2R1 antibodies are detected in approximately 70% to 80% and anti-THSD7A antibodies in only 2% of adult patients with iMN. The presence of anti-THSD7A antibodies is associated with increased risk of malignancy. The assessment of PLA2R1 and THSD7A antigen expression in glomerular immune deposits has a better sensitivity than measurement of the corresponding autoantibodies. Therefore, in the presence of circulating anti-podocytes autoantibodies and/or enhanced expression of PLA2R1 and THSD7A antigens MN should be considered as primary MN (pMN). Anti-PLA2R1 or anti-THSD7A autoantibodies have been proposed as biomarkers of autoimmune disease activity and their blood levels should be regularly monitored in pMN to evaluate disease activity and predict outcomes. We propose a revised clinical workup flow for patients with MN that recommends assessment of kidney biopsy for PLA2R1 and THSD7A antigen expression, screening for circulating anti-podocytes antibodies, and assessment for secondary causes, especially cancer, in patients with THSD7A antibodies. Persistence of anti-podocyte antibodies for 6 months or their increase in association with nephrotic proteinuria should lead to the introduction of immunosuppressive therapies. Recent data have reported the efficacy and safety of new specific therapies targeting B cells (anti-CD20 antibodies, inhibitors of proteasome) in pMN which should lead to an update of currently outdated treatment guidelines.