A case report of remission of refractory membranous nephropathy progressing to stage 4 chronic kidney disease using low-dose rituximab: A long-term follow-up

Treatment of exostosin 1-associated membranous lupus nephritis with multiple low doses of rituximab: A case report

RATIONALE

Membranous glomerulonephritis (MN) is the leading cause of nephrotic syndrome in adults and is classified as primary or secondary. Secondary MN accounts for 20% to 30% of all MN cases and can arise from a number of conditions, including autoimmune diseases. Recently exostosin 1/exostosin 2 (EXT1/EXT2) have been identified as the common antigens in secondary autoimmune MN and are present in cases of pure membranous lupus nephritis (LN). The treatment of EXT1/EXT2-associated MN remains elusive.

PATIENT CONCERNS

We present the case of a 15-year-old female who presented with nephrotic syndrome, positive ANA and dsDNA, and low serum complements. A renal biopsy revealed pure membranous nephritis with IgG and C3 deposition. EXT1 was found along the glomerular capillary walls and stained positive, while phospholipase A2 receptor (PLA2R) and thrombospondin type-1 domain-containing 7A (THSD7A) were negative.

DIAGNOSIS

The patient was diagnosed with ETX1-associated membranous LN.

INTERVENTIONS

She was treated with prednisone and multiple low-dose rituximab (4 200 mg doses, approximately every 2 months, based on CD19+ cells counts).

OUTCOMES

The patient had complete remission within 8 months later, and she remained in remission for the 16-month period of follow-up.

LESSONS

To our knowledge, this is the first case of EXT1-associated MN that has been successfully treated by multiple low-dose rituximab. Further studies can investigate the optimal dosage and treatment protocol.

Rituximab in Patients With Phospholipase A2 Receptor-Associated Membranous Nephropathy and Severe CKD

Introduction

Patients with phospholipase A2 receptor (PLA2R)–associated membranous nephropathy and stage 4 or 5 chronic kidney disease are at high risk of end-stage kidney disease. In recent years, rituximab (RTX) emerged as a safe and efficient treatment for patients with PLA2R-associated membranous nephropathy. Whether its use is also appropriate in patients with an estimated glomerular filtration rate <30 ml/min per 1.73 m² has not been investigated.

Methods

We retrospectively reviewed characteristics and outcome of 13 patients with PLA2R-associated membranous nephropathy and stage 4 or 5 chronic kidney disease who received a total of 14 consecutive RTX treatments from January 2012 to March 2018. The treatment regimen consisted of either 2 weekly infusions of 375 mg/m² or 2 RTX infusions of 1 g/d two weeks apart. When needed, the regimen was repeated to achieve immunological remission.

Results

The mean estimated glomerular filtration rate, serum albumin level, and urinary protein level at the first RTX infusion were 18 ± 7 ml/min per 1.73 m², 25.2 ± 5.4 g/l, and 13.2 ± 7.5 g/d, respectively, with all patients being tested positive for serum PLA2R antibodies. Ten treatment courses led to an increase in estimated glomerular filtration rate and remission of nephrotic syndrome after a median follow-up of 40.8 months (interquartile range, 14.8–46.8). Conversely, 4 RTX treatments were unsuccessful, with patients requiring chronic hemodialysis within 1 year. The urinary albumin-to-protein ratio before treatment was predictive of renal response. Immunological remission occurred after 11 treatment courses and was associated with clinical response in 10 of 11 patients. Three patients experienced severe adverse events.

Conclusion

RTX seems effective and reasonably safe in PLA2R-associated membranous nephropathy with stage 4 or 5 chronic kidney disease. Immunological remission is associated with a good clinical outcome.