Influenza vaccination-associated cryoglobulinemic vasculitis.

Mixed cryoglobulinemia is a small vessel vasculitis associated with viral infections, mainly hepatitis C virus, however, other important causes include lymphoproliferative and autoimmune disorders. Influenza vaccine-induced cryoglobulinemia has been rarely reported. A 68-year-old male presented on three occasions following influenza vaccination with purpuric rash and lower extremities swelling. His lab work showed mixed cryoglobulins. On his most recent presentation, in addition to the purpura, he presented with thrombocytopenia and nephritic syndrome. A kidney biopsy showed endocapillary proliferative glomerulonephritis with organized deposits, consistent with mixed type cryoglobulinemic glomerulonephritis. The patient was treated with rituximab infusion with progressive improvement of the acute kidney injury (AKI) and complete recovery. It is unclear why cryoglobulins are produced as a response to a vaccination, but this association is important to be aware of for prompt monitoring and treatment.

Obinutuzumab as treatment for ANCA-associated vasculitis.

OBJECTIVES: Rituximab is a standard of care therapy for patients with ANCA-associated vasculitis. When rituximab is contraindicated, or in the case of refractory disease, other treatments are needed. Obinutuzumab is another anti-CD20 antibody for the treatment of haematological malignancies that may induce a deeper B cell depletion compared with rituximab. This article reviews three cases of patients with ANCA-associated vasculitis who were treated with obinutuzumab due to their history of anaphylactic reactions to rituximab. METHODS: Case series of three patients with ANCA-associated vasculitis treated with obinutuzumab. RESULTS: One female patient with microscopic polyangiitis and two male patients with granulomatosis with polyangiitis received obinutuzumab. The treatment was well-tolerated in all patients despite previous anaphylactic reaction to rituximab. Treatment with obinutuzumab was effective in (i) inducing disease remission, (ii) inducing total B cell depletion, and (iii) resulting in undetectable serum titres of ANCA. All three patients were re-treated with obinutuzumab for maintenance of remission. CONCLUSION: Obinutuzumab appears to be a safe and efficacious therapy for patients with ANCA-associated vasculitis who have had refractory disease or a history of anaphylaxis to rituximab. Prospective studies comparing rituximab to obinutuzumab in ANCA-associated vasculitis patients are warranted.

Deferasirox-associated Fanconi syndrome in adult patients with transfusional iron overload.

BACKGROUND AND OBJECTIVES: Deferasirox is an oral chelator approved for iron overload, which has a potential side effect of renal Fanconi syndrome, with proximal tubular dysfunction and tubular acidosis. Monitoring of renal function is recommended, though no standard for monitoring exists. We aim to describe cases of deferasirox-associated Fanconi syndrome in adults and the renal monitoring required to detect these findings. MATERIALS AND METHODS: We present a review of the literature and six cases from our institution of deferasirox-associated partial Fanconi syndrome in adult patients with transfusional iron overload secondary to ß-thalassemia or Diamond Blackfan Anaemia. RESULTS: While prior cases in the literature occurred at high doses of deferasirox, our series included patients on doses as low as deferasirox 10 mg/kg who had been aggressively chelated. All patients had resolution of laboratory abnormalities with drug interruption. CONCLUSION: Rather than chelating to normal iron levels, this series supports prior suggestions that deferasirox dose be reduced if ferritin <500-1000 ng/ml, and also supports dose reduction if liver iron content <3 mg iron per g dry weight or for those undergoing aggressive chelation with rapid decrease in iron. Monitoring with metabolic panel and urinalysis were sufficient to detect clinically significant proximal tubular dysfunction, but should be followed up with additional studies to confirm the diagnosis while deferasirox dose is decreased or held.

Bevacizumab-associated thrombotic microangiopathy treated with eculizumab: A case series and systematic review of the literature.

BACKGROUND: Bevacizumab is a recombinant monoclonal antibody against the vascular endothelial growth factor A (VEGF-A) ligand that is used in the management of various solid malignancies. The adverse effect profiles of angiogenesis inhibitors, such as bevacizumab, have become increasingly well characterized and include renal manifestations such as hypertension, proteinuria, and thrombotic microangiopathy. Eculizumab inhibits terminal-complement activation and is used to treat atypical hemolytic uremic syndrome. There has been growing usage of eculizumab to treat bevacizumab-associated thrombotic microangiopathy. MATERIALS AND METHODS: We performed a systematic review of the literature to identify full-text articles that describe the use of eculizumab for bevacizumab-associated thrombotic microangiopathy. RESULTS: Our systematic review identified 522 unique articles of which 5 were included in the final review. 9 cases, including 2 new cases presented in this review, were identified in which eculizumab was used in the management of bevacizumab-associated thrombotic microangiopathy. Hematologic parameters and kidney function stabilized or improved in all cases, and the 2 patients who required renal replacement therapy were able to discontinue dialysis. CONCLUSIONS: Given the findings of this systematic review, the use of eculizumab in the treatment of bevacizumab-associated thrombotic microangiopathy warrants further study, particularly in severe cases.

Real-World Experience With Avacopan in Antineutrophil Cytoplasmic Autoantibody-Associated Vasculitis.

Introduction: Postmarketing data on outcomes of avacopan use in antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) are lacking. Methods: We performed a multicenter retrospective analysis of 92 patients with newly diagnosed or relapsing AAV who received therapy with avacopan. The coprimary outcome measures were clinical remission at 26 and 52 weeks. We use descriptive statistics and univariate logistic regression to assess outcomes and predictors of remission, respectively. Results: Of the 92 patients, 23% (n = 21) had a baseline estimated glomerular filtration rate (eGFR) < 15 ml/min per 1.73 m2 and 10% on kidney replacement therapy at baseline. Among those with kidney involvement, mean (SD) enrollment eGFR was 33 (27) ml/min per 1.73 m2 with a mean (SD) change of +12 (25) and +20 (23) ml/min per 1.73 m2 at weeks 26 and 52, respectively. In addition to avacopan, 47% of patients received combination therapy of rituximab and low-dose cyclophosphamide, and 14% of patients received plasma exchange (PLEX). After induction, the median (interquartile range [IQR]) time to start avacopan was 3.6 (2.1-7.7) weeks, and the median time to discontinue prednisone after starting avacopan was 5.6 (3.3-9.5) weeks. Clinical remission was achieved in 90% of patients at week 26 and 84% of patients at week 52. Of the patients, 20% stopped avacopan due to adverse events, with the most common being elevated serum aminotransferases (4.3%). Conclusion: A high rate of remission and an acceptable safety profile were observed with the use of avacopan in the treatment of AAV in this postmarketing analysis, including the populations excluded from the ADVOCATE trial.

Toxicokinetics of metformin-associated lactic acidosis with continuous renal replacement therapy.

A 70-year-old diabetic male patient with a baseline serum creatinine of 1.4 mg/dL presented with nausea and vomiting. He was diagnosed with metformin-associated lactic acidosis and acute kidney injury. He was managed with continuous veno-venous hemodiafiltration (CVVHDF). By measuring metformin concentration at different time intervals, we calculated the apparent volume of distribution of metformin at 34.7 L. The decline in serum metformin followed single-compartment first-order kinetics with an elimination rate constant of 0.0418/h and a serum half-life of 16.5 h; no metformin rebound was seen after discontinuation of CVVHDF. Using the previously calculated volume of distribution we calculated the expected serum metformin concentration 25 h post CVVHDF to be 3.0-3.7 µg/mL. The measured serum metformin of 3.4 µg/ml fell within the predicted range. During CVVHDF, dialyzer metformin clearance approximates 88.7 % of dialyzer urea clearance and 90.1 % of dialyzer creatinine clearance.

The impact of reporting estimated glomerular filtration rate.

The 'Kidney Disease Outcomes Quality Initiative' guidelines recommend laboratory reporting of a calculated estimated glomerular filtration rate (eGFR). The United Kingdom and several states already mandate reporting eGFR for every laboratory serum creatinine (sCr) measurement. In our study, we evaluated the impact of reporting eGFR on the management of hospitalized patients. We reviewed the medical records for 2000 patients, 1000 pre- and 1000 post-reporting eGFR. We excluded patients with previous diagnosis of chronic kidney disease, acute kidney failure, and end-stage renal disease. We analyzed the subgroup of patients with eGFR <60 and sCr <1.5 mg/dL. We did not notice an increase in the number of renal consult, ordering laboratory or imaging study to evaluate chronic kidney disease. The prescription habits did not change for nephrotoxic medications (nonsteroidal anti-inflammatory drugs and aminoglycosides). We did not find any change in the percentage of patients who received hydration for a radiological contrast study or the use of N-acetylcysteine. In conclusion, reporting eGFR did not improve the renal management of hospitalized patients.

Worsening membranous nephropathy in a patient with GIST treated with sunitinib.

Tyrosine kinase inhibitors (TKI) are anticancer agents widely used for a variety of malignancies including gastrointestinal stromal tumours (GIST). Although generally well-tolerated, TKIs have been associated with a number of adverse events including hypertension, proteinuria and nephrotic syndrome. We present the case of a 70-year-old patient with metastatic GIST on long-standing sunitinib who developed hypertension, oedema and hypoalbuminemia with a rising serum creatinine and was found to have nephrotic syndrome. Workup revealed elevated antiphospholipase A2 receptor (PLA2R) antibody IgG titres and a kidney biopsy confirmed PLA2R-positive membranous nephropathy without findings of thrombotic microangiopathy. Cessation of sunitinib led to reduction in anti-PLA2R antibody IgG titres while resumption, due to concern for cancer progression, led to worsening symptoms. Treatment with rituximab led to undetectable anti-PLA2R IgG titres. We highlight the importance of maintaining a systematic approach for evaluating nephrotic syndrome and provide a case showing that TKIs can exacerbate underlying nephrotic syndrome.

Bortezomib Treatment for Refractory PLA2R-Positive Membranous Nephropathy.

Introduction: B-cell depletion has been shown to be an effective strategy for the majority of patients with membranous nephropathy (MN), and in PLA2R-positive MN, immunologic remission (improvement or elimination of measurable serum anti-PLA2R antibodies) precedes renal remission. Yet, cases exist of patients who do not achieve immunologic remission despite achieving peripheral B-cell depletion. This has led to the hypothesis that some patients have plasma cells that are responsible for producing anti-PLA2R antibodies. Case Presentation: A 66-year-old man with a past medical history of hypertension, hyperlipidemia, and cerebrovascular disease presented with nephrotic syndrome and was diagnosed with PLA2R-positive MN on kidney biopsy. He was refractory to multiple therapies including tacrolimus, and was resistant to rituximab despite having achieved B-cell depletion. He also did not enter into remission with plasmapharesis and cyclophosphamide. He then achieved immediate immunologic remission after treatment with the proteasome inhibitor bortezomib, which is used as first-line therapy for multiple myeloma. Discussion/Conclusion: This case suggests that considering the source of PLA2R antibody production could lead to individualized and targeted therapies for MN.

Nephrotoxicity From Molecularly Targeted Chemotherapeutic Agents.

The introduction of novel molecularly targeted therapies in the last 2 decades has significantly improved the patient survival compared to standard conventional chemotherapies. However, this improvement has been accompanied by a whole new spectrum of kidney adverse events. Although known as "targeted," many of these agents lack specificity and selectivity, and they have a tendency to inhibit multiple targets including those in the kidneys. Early detection and correct management of kidney toxicities is crucial to preserve kidney functions. The knowledge of these toxicities helps guide optimal and continued utilization of these potent therapies. The incidence, severity, and pattern of nephrotoxicity may vary depending on the respective target of the drug. Here, we review the mechanism of action, clinical findings of kidney adverse events, and their proposed management strategies.

Effects of parathyroid hormone on immune function.

Parathyroid hormone (PTH) function as immunologic mediator has become interesting with the recent usage of PTH analogue (teriparatide) in the management of osteoporosis. Since the early 1980s, PTH receptors were found on most immunologic cells (neutrophils, B and T cells). The in vitro evaluations for a possible role of PTH as immunomodulator have shown inconsistent results mainly due to methodological heterogeneity of these studies: it used different PTH formulations (rat, bovine, and human), at different dosages and different incubating periods. In some of these studies, the lymphocytes were collected from uremic patients or animals, which renders the interpretation of the results problematic due to the effect of uremic toxins. Parathyroidectomy has been found to reverse the immunologic defect in patients with high PTH levels. Nonetheless, the clinical significance of these findings is unclear. Further studies are needed to define if PTH does have immunomodulatory effects.