Alpha-interferon-associated thrombotic microangiopathy: a clinicopathologic study of 8 patients and review of the literature

Clinical characteristics, treatments, and outcomes of interferon-beta-induced thrombotic microangiopathy: a literature-based retrospective analysis

Background

Thrombotic microangiopathy (TMA) is a rare side effect of interferon-beta (IFN-β) therapy. The clinical characteristics of IFN-β-induced TMA are unknown.

Objectives

To explore the clinical characteristics of IFN-β-induced TMA and provide reference for the prevention of TMA.

Design

Articles on IFN-β-induced TMA were collected by searching the literature in relevant Chinese and English databases from inception to 31 July 2023.

Methods

Data in the articles were extracted and analyzed retrospectively.

Results

Forty-seven patients, with a median age of 41 years (range 22, 66), were included in the analysis. The median time to the diagnosis of IFN-β-induced TMA was 8 years (range 0.1-30) after administration. The main clinical symptoms were neurological symptoms (51.1%), hypertension (78.7%), dyspnea (19.1%), edema (19.1%), asthenia/fatigue (19.1%), and digestive symptoms (17.0%). Most patients presented with hemolytic anemia (76.6%), thrombocytopenia (63.8%), and acute kidney injury (70.2%). All patients stopped IFN-β and received plasma exchange therapy (53.2%), systemic steroids (46.8%), antihypertensive therapy (46.8%), eculizumab (12.8%), and rituximab (12.8%). Kidney damage was not completely reversible; 40.4% of patients achieved renal function and hematology remission, 27.7% developed chronic kidney disease, 25.5% developed end-stage renal disease, and 2.1% died.

Conclusion

IFN-β-induced TMA is a rare but serious complication that can be life-threatening. It may occur after many years of IFN-β therapy, and patients taking IFN-β should be monitored for symptoms such as headache and hypertension.

Chapter 1: Evaluation of kidney function in patients undergoing anticancer drug therapy, from clinical practice guidelines for the management of kidney injury during anticancer drug therapy 2022

The prevalence of CKD may be higher in patients with cancer than in those without due to the addition of cancer-specific risk factors to those already present for CKD. In this review, we describe the evaluation of kidney function in patients undergoing anticancer drug therapy. When anticancer drug therapy is administered, kidney function is evaluated to (1) set the dose of renally excretable drugs, (2) detect kidney disease associated with the cancer and its treatment, and (3) obtain baseline values for long-term monitoring. Owing to some requirements for use in clinical practice, a GFR estimation method such as the Cockcroft-Gault, MDRD, CKD-EPI, and the Japanese Society of Nephrology's GFR estimation formula has been developed that is simple, inexpensive, and provides rapid results. However, an important clinical question is whether they can be used as a method of GFR evaluation in patients with cancer. When designing a drug dosing regimen in consideration of kidney function, it is important to make a comprehensive judgment, recognizing that there are limitations regardless of which estimation formula is used or if GFR is directly measured. Although CTCAEs are commonly used as criteria for evaluating kidney disease-related adverse events that occur during anticancer drug therapy, a specialized approach using KDIGO criteria or other criteria is required when nephrologists intervene in treatment. Each drug is associated with the different disorders related to the kidney. And various risk factors for kidney disease associated with each anticancer drug therapy.

Management of Hepatitis C Virus and Hepatitis B Virus Infection in the Setting of Kidney Disease

Treatment of chronic hepatitis C virus (HCV) and hepatitis B virus (HBV) infection poses unique challenges in patients with kidney disease. Direct-acting antivirals have been a major breakthrough in eradicating HCV infection, and several pangenotypic regimens are available for patients with chronic kidney disease or end-stage kidney disease requiring dialysis with high cure rates and no need for dose adjustment. Direct-acting antiviral therapy alone can treat HCV-associated cryoglobulinemic glomerulonephritis; concurrent antiviral and immunosuppressive therapy is needed for cases of severe, organ-threatening manifestations of cryoglobulinemia. Immunosuppression may be needed for HBV-associated kidney disease (polyarteritis nodosa or membranous nephropathy) when there is evidence of severe immune-mediated injury while weighing the risk of potential viral activation. Most HBV antiviral agents need to be dose-adjusted in patients with chronic kidney disease or end-stage kidney disease requiring dialysis, and drug-drug interactions need to be carefully evaluated in patients with kidney transplants. Considerations for accepting HCV- and HBV-infected donors for kidney transplantation are discussed.

Thrombotic thrombocytopenic purpura in a patient on long-term alpha-interferon therapy for essential thrombocythemia: a case report

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP) is rare and severe thrombotic microangiopathy characterized by thrombocytopenia, hemolytic anemia, and renal dysfunction. In contrast, essential thrombocythemia (ET) is a myeloproliferative disease associated with an abnormal increase in platelet numbers. Previous studies reported several cases of the development of ET in patients with TTP. However, the case of an ET patient complicated with TTP has not been previously reported. In this case study, we present a patient with TTP who was previously diagnosed with ET. Therefore, to the best of our knowledge, this is the first report of TTP in ET.

CASE PRESENTATION

A 31-year-old Chinese female who was previously diagnosed with ET presented with anemia and renal dysfunction. The patient had been on long-term treatment with hydroxyurea, aspirin, and alpha interferon (INF-α) for ten years. The diagnosis of TTP was confirmed by clinical features, schistocytes noted on the peripheral blood smear, and lower ADAMTS13 activity (8.5%), together with the renal biopsy results. INF-α was discontinued, and the patient was then treated with plasma exchange and corticosteroids. After one year of follow-up, the patient had a normal hemoglobin level and platelet numbers, and her ADAMTS13 activity had improved. However, the patient's renal function remains impaired.

CONCLUSIONS

We report a case of an ET patient complicated with TTP that was possibly due to INF-α, highlighting the potential complications associated with long-term ET therapy. The case also highlights the importance of considering TTP in patients with pre-existing ET who present with anemia and renal dysfunction, extending the spectrum of known studies.

The Link Between Conventional and Novel Anti-Cancer Therapeutics with Thrombotic Microangiopathy

BACKGROUND

Kidney disease associated with cancer and anti-cancer therapies has been increasingly recognized in the field of onco-nephrology. In particular, drug-induced nephrotoxicity has important implications since most chemotherapeutic agents have a nephrotoxic potential. Also, standard creatinine clearance methods used for the measurement of kidney function have been questioned in cancer patients due to factors like low muscle mass and poor nutritional status. Overestimations of the glomerular filtration rate, not only can increase the nephrotoxic potential of different agents, but also further limit the use of first-line therapies.

OBJECTIVE

This review covers specifically the drug-induced thrombotic microangiopathy and its two pathophysiologic mechanisms which include immune or idiosyncratic reactions, and non-immune or dose-dependent ones.

CONCLUSION

As novel cancer therapies are developed, it is paramount to pursue a better understanding of conventional and novel chemotherapeutic agents and their role in kidney disease.

The link between kidney disease and cancer: complications and treatment

Acute and chronic kidney disease encompasses a complex set of diseases that can both lead to, and result from, cancer. In particular, kidney disease can arise from the use of chemotherapeutic agents. Many of the current and newly developed cancer chemotherapeutic agents are nephrotoxic and can promote kidney dysfunction, which frequently manifests during the terminal stages of cancer. Given the link between kidney disease and cancer development and treatment, the aim of this Review is to highlight the importance of multidisciplinary collaboration between oncologists and nephrologists to predict and prevent chemotherapeutic-induced nephrotoxicity. As new therapies are introduced to treat cancer, new renal toxicities require proper diagnosis and management. We anticipate that multidisciplinary collaborations will lead to the development and implementation of guidelines for clinicians to improve the therapeutic management of patients with both cancer and renal impairment.

Thrombotic Microangiopathy in Interferon-beta-Treated Multiple Sclerosis Patient

A 43-year-old man who was treated with interferon-beta for multiple sclerosis was presented with hypertension, headache, nausea/vomiting, blurred vision, and renal dysfunction. The treatment with drugs and dialysis relieved the symptoms. Despite plasmapheresis is known to cause improvement in renal function, no such improvement was seen in patient.

Nephrotoxicity in cancer treatment: An overview

Anticancer drug nephrotoxicity is an important and increasing adverse drug event that limits the efficacy of cancer treatment. The kidney is an important elimination pathway for many antineoplastic drugs and their metabolites, which occurs by glomerular filtration and tubular secretion. Chemotherapeutic agents, both conventional cytotoxic agents and molecularly targeted agents, can affect any segment of the nephron including its microvasculature, leading to many clinical manifestations such as proteinuria, hypertension, electrolyte disturbances, glomerulopathy, acute and chronic interstitial nephritis, acute kidney injury and at times chronic kidney disease. The clinician should be alert to recognize several factors that may maximize renal dysfunction and contribute to the increased incidence of nephrotoxicity associated with these drugs, such as intravascular volume depletion, the associated use of nonchemotherapeutic nephrotoxic drugs (analgesics, antibiotics, proton pump inhibitors, and bone-targeted therapies), radiographic ionic contrast media or radiation therapy, urinary tract obstruction, and intrinsic renal disease. Identification of patients at higher risk for nephrotoxicity may allow the prevention or at least reduction in the development and severity of this adverse effect. Therefore, the aim of this brief review is to provide currently available evidences on oncologic drug-related nephrotoxicity.

Broad spectrum of interferon-related nephropathies-glomerulonephritis, systemic lupus erythematosus-like syndrome and thrombotic microangiopathy: A case report and review of literature

BACKGROUND

Interferons (IFNs) are characterized by a wide range of biological effects, which justifies their potential therapeutic use in several pathologies, but also elicit a wide array of adverse effects in almost every organ system. Among them, renal involvement is probably one of the most complex to identify.

CASE SUMMARY

We describe four cases of kidney damage caused by different IFN formulations: IFN-β-related thrombotic microangiopathy, IFN-β-induced systemic lupus erythematosus, and two cases of membranous nephropathy secondary to pegylated-IFN-α 2B. In each case, we carefully excluded any other possible cause of renal involvement. Once suspected as the casual relationship between drug and kidney damage, IFN treatment was immediately discontinued. In three cases, we observed a complete and persistent remission of clinical and laboratory abnormalities after IFN withdrawal, while the patient who developed thrombotic microangiopathy, despite IFN withdrawal and complement-inhibitor therapy with eculizumab, showed persistent severe renal failure requiring dialysis.

CONCLUSION

This case series highlights the causal relationship between IFN treatment and different types of renal involvement and enables us to delineate several peculiarities of this association.

The adverse kidney effects of cancer immunotherapies

Cancer therapies are a common cause of acute and chronic kidney disease, which are increasingly being seen by nephrologists in clinical practice. Conventional chemotherapeutic drugs and novel targeted agents are effective cancer therapies but their use is complicated by nephrotoxicity. Cancer immunotherapies exploit various properties of immune cells to enhance immune-mediated tumor killing. Interferon and high-dose interleukin-2 are older immunotherapies first employed clinically in the 1980s and 1990s to treat a number of different cancers. While effective, these two therapies have well-known systemic toxicities, which include acute kidney disease. The emergence of the new cancer immunotherapies over the past decade brings more effective treatment options. The immune checkpoint inhibitors and chimeric antigen receptor T cells are exciting additions to the cancer treatment armamentarium. These agents effectively treat a several and a growing list of cancers that have otherwise failed other therapies. However, as with the conventional and targeted cancer agents, drug-induced acute and chronic kidney disease is an untoward effect of this group of drugs. We will undertake a case-based review: the newer immunotherapies followed by the older therapies, interferon and interleukin-2.

Drug-induced Glomerulonephritis: The Spectre of Biotherapeutic and Antisense Oligonucleotide Immune Activation in the Kidney

Prevalence of immune-mediated glomerulonephritis has increased in preclinical toxicity studies, with more frequent use of biotherapeutic agents (especially antigenic humanized molecules) and antisense oligonucleotide (ASO) therapies. Immune complex disease affects a small number of study monkeys, often correlates with antidrug antibody (ADA) titers, and occurs at a dose that favors immune complex formation or impedes clearance. While preclinical glomerulonephritis often fails to correlate with evidence of glomerular or vascular injury in human clinical trials and is not considered predictive, additional animal investigative immunohistochemical work may be performed to substantiate evidence for immune complex pathogenesis. While ADA is most commonly encountered as a predisposing factor with biotherapeutic agents, complement activation may occur without circulating complexes, and other mechanisms of non-ADA immune-mediated glomerulonephritis have been observed including nonendogenous immune aggregates and immunoregulatory pharmacology. Although glomerulonephritis associated with oligonucleotide therapies has been noted occasionally in preclinical studies and more rarely with human patients, pathophysiologic mechanisms involved appear to be different between species and preclinical cases are not considered predictive for humans. ADA is not involved in oligonucleotide-associated cases, and complement fixation plays a more important role in monkeys. Recent screening of ASOs for proinflammatory activity appears to have decreased glomerulonephritis incidence preclinically.

Nephrotoxicity of Cancer Immunotherapies: Past, Present and Future

Nephrotoxicity from cancer therapies is common and increasingly encountered in clinical practice, such that the subfield of "onco-nephrology" has emerged. Conventional chemotherapeutic drugs and novel agents targeting specific genes/proteins are effective cancer therapies but suffer from a number of adverse kidney effects. An effective avenue of cancer treatment is immunotherapy, which uses drugs that augment immune system-mediated recognition and targeting of tumor cells. As such, leveraging the immune system to target malignant cells represents an important modality in eradicating cancer. IFN and high-dose IL-2 are older immunotherapies used in clinical practice to treat various malignancies, whereas new cancer immunotherapies have emerged over the past decade that offer even more effective treatment options. The immune checkpoint inhibitors are an exciting addition to the cancer immunotherapy armamentarium. Chimeric antigen receptor T cells are also a new immunotherapy used to treat various hematologic malignancies. However, as with the conventional and targeted cancer agents, the immunotherapies are also associated with immune-related adverse effects, which includes nephrotoxicity.

Nephrotoxicity of anticancer treatment

Severe adverse systemic drug events occur commonly as a result of treatment of cancer patients. Nephrotoxicity of chemotherapeutic agents remains a significant complication limiting the efficacy of the treatment. A variety of renal disease and electrolyte disorders can result from the drugs that are used to treat malignant disease. The kidneys are a major elimination pathway for many antineoplastic drugs and their metabolites. Tumour lysis syndrome, an emergency in haematooncology, occurs most often after the initiation of cytotoxic therapy in patients with high-grade lymphomas and acute lymphoblastic leukaemia. Chemotherapeutic agents can affect the glomerulus, tubules, interstitium and renal microvasculature, with clinical manifestations that range from asymptomatic elevation of serum creatinine to acute renal failure requiring dialysis. Some factors such as intravascular volume depletion, as well as concomitant use of other drugs or radiographic ionic contrast media, can potentiate or contribute to the nephrotoxicity. Cytotoxic agents can cause nephrotoxicity by a variety of mechanisms. The most nephrotoxic chemotherapeutic drug is cisplatin, which is often associated with acute kidney injury. Many other drugs such as alkylating agents, antimetabolites, vascular endothelial growth factor pathway inhibitors and epidermal growth factor receptor pathway inhibitors may have toxic effects on the kidneys. The aim of this review is to discuss the issue of nephrotoxicity associated with chemotherapy. In routine clinical practice, monitoring of kidney function is mandatory in order to identify nephrotoxicity early, allowing dosage adjustments or withdrawal of the offending drug.

[Hemolytic and uremic syndrome and related thrombotic microangiopathies: Epidemiology, pathophysiology and clinics]

Thrombotic microangiopathies (TMA) represent an eclectic group of conditions, which share hemolytic anemia and thrombocytopenia as a common defining basis. Remarkable breakthroughs in the physiopathological setting have allowed for a thorough recomposition of the disparate syndromes, which form the constellation of TMA. In this view, clinicians now discriminate thrombocytopenic thrombotic purpura (TTP) defined by a severe deficiency in ADAMTS13, which is rarely associated with a severe renal involvement and the hemolytic and uremic syndrome (HUS) in which renal impairment is the most prominent clinical feature. HUS can result from toxins stemming from bacterial infections of the digestive tract, alternate complement pathway abnormalities, metabolic or coagulation disorders or, lastly, drug and various toxic compounds. The diverse forms of HUS reflect the insights gained in the understanding of the pathophysiological mechanisms underpinning TMA. In this first part, a broad overview of the epidemiological, physiopathological and clinical aspects of HUS and related TMA syndromes is presented.

Immune checkpoint inhibitors renal side effects and management

The choice of immunotherapy in the treatment of cancer has improved the prognosis of many patients affected by various malignancies. The high expectations foreseen with immunotherapy have led to fast approvals despite the incomplete understanding of the toxicity profiles in the different organs, including the kidneys. The high prevalence of chronic kidney disease in cancer patients complicates the issue further and requires a better knowledge of the renal safety profile to ensure an optimal safe treatment. This review summarizes the present knowledge of renal adverse events secondary to immune checkpoint inhibitors and discusses their pathophysiology, clinical presentation and adequate management. We also advocate the need for a multidisciplinary approach in patients with immune-related toxic adverse events.

Interferon induced thrombotic microangiopathy (TMA): Analysis and concise review

Interferon (IFN) has been associated with development of thrombotic microangiopathy including thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS). We reviewed literature from the earliest reported association in 1993, to July 2016 and found 68 cases. Analysis of this data shows: (1) Mean age at diagnosis was 47 years (95% CI, 44-50). (2) Majority of cases were seen where IFN was used for the treatment of chronic myelogenous leukemia (CML), multiple sclerosis (MS), chronic hepatitis C virus infection (HCV) and one case each for hairy cell leukemia (HCL) and Sezary syndrome. (3) There were no cases reported for polycythemia vera (PV) or lymphoma. (4) Sex distribution was nearly equivalent with the exception in patients with multiple sclerosis where there was female predominance (12 of 16 with reported data). (5) For pooled analysis, the average duration of treatment with IFN before TMA was diagnosed was 40.4 months. (6) Comparative analysis showed that patients with MS required the highest cumulative dose exposure before developing TMA (MS 68.6 months, CML 35.5 months, HCV 30.4 months). (7) Cases of confirmed TTP (where A disintegrin and Metalloprotease with thrombospondin type 1 motif 13: ADAMTS 13 level was measured) showed presence of an inhibitor. (8) In all cases of confirmed TTP, moderate to severe thrombocytopenia was a striking clinical feature at presentation while this was not a consistent finding in all other cases of TMA. (9) Outcome analysis revealed complete remission in 27 (40%), persistent chronic kidney disease (CKD) in 28 (42%) and fatality in 12 patients (18%). (10) Treatment with corticosteroids, plasma exchange and rituximab resulted in durable responses.

Type I interferon causes thrombotic microangiopathy by a dose-dependent toxic effect on the microvasculature

Many drugs have been reported to cause thrombotic microangiopathy (TMA), yet evidence supporting a direct association is often weak. In particular, TMA has been reported in association with recombinant type I interferon (IFN) therapies, with recent concern regarding the use of IFN in multiple sclerosis patients. However, a causal association has yet to be demonstrated. Here, we adopt a combined clinical and experimental approach to provide evidence of such an association between type I IFN and TMA. We show that the clinical phenotype of cases referred to a national center is uniformly consistent with a direct dose-dependent drug-induced TMA. We then show that dose-dependent microvascular disease is seen in a transgenic mouse model of IFN toxicity. This includes specific microvascular pathological changes seen in patient biopsies and is dependent on transcriptional activation of the IFN response through the type I interferon α/β receptor (IFNAR). Together our clinical and experimental findings provide evidence of a causal link between type I IFN and TMA. As such, recombinant type I IFN therapies should be stopped at the earliest stage in patients who develop this complication, with implications for risk mitigation.

Drug-induced glomerular disease: direct cellular injury

The potential of medications to cause kidney injury is well known. Although nephrotoxicity is most commonly associated with injury in the tubulointerstitial compartment as either acute tubular necrosis or acute interstitial nephritis, a growing body of literature has also highlighted the potential for drug-induced glomerular lesions. This review surveys the three primary patterns of drug-induced glomerular diseases stratified by the cell type at which the glomerular lesion is focused: visceral epithelial cell (or podoctye) injury, endothelial cell injury, and mesangial cell injury. A number of commonly prescribed medications, including IFNs, bisphosphonates, nonsteroidal anti-inflammatory drugs, antiplatelet agents, and antiangiogenesis drugs, that are both prescribed and available over the counter, have been implicated in these iatrogenic forms of glomerular disease. Recognition of these drug-induced etiologies of glomerular disease and rapid discontinuation of the offending agent are critical to maximizing the likelihood of renal function recovery.

Hypertension and hepatitis C virus infection are strong risk factors for developing late renal dysfunction after living donor liver transplantation: significance of renal biopsy

BACKGROUND

Late renal dysfunction (LRD) after liver transplantation develops due to several factors such as viral hepatitis, calcineurin inhibitor, diabetes mellitus, and hypertension. The aim of our study was to clarify the risk factors for LRD after living donor liver plantation (LDLT) by using simple criteria for LRD and paying special attention to the significance of renal biopsy.

PATIENTS AND METHODS

Among the 98 recipients undergoing LDLT between March 2002 and June 2008, there were 77 patients who survived more than 1 year and had been followed at our clinic. LRD was simply defined as a postoperative serum creatinine level of 1.5/L or more at any point in time after 1 year from undergoing LDLT. The perioperative risk factors for developing LRD after LDLT were analyzed by uni- and multivariate analyses, and regardless of serum creatinine level, a renal biopsy was indicated when the patient developed clinical symptoms.

RESULTS

Comparing the risk factors between 22 patients with LRD and 55 without LRD, univariate analysis revealed recipient's age, generation, hypertension, hepatitis C virus (HCV) antibody-positive, pretransplantation serum creatinine level, and graft-to-recipient weight ratio to be significant risk factors. By multivariate analysis, HCV and hypertension were selected as independent risk factors. Renal biopsy was indicated in the 4 patients with proteinuria, all of whom were positive for HCV. However, by histologic and/or electron micrographic analyses, only 1 patient was diagnosed with HCV-related membranous proliferative nephritis, 1 with diabetic nephropathy, and 2 with drug (tacrolimus) -induced renal dysfunction.

CONCLUSION

Although HCV and hypertension were determined to be independent risk factors for LRD after LDLT, a renal biopsy should be performed when clinical symptoms develop regardless of creatinine levels to provide appropriate treatment.

Side effects of cytokines approved for therapy

Cytokines, currently known to be more than 130 in number, are small MW (<30 kDa) key signaling proteins that modulate cellular activities in immunity, infection, inflammation and malignancy. Key to understanding their function is recognition of their pleiotropism and often overlapping and functional redundancies. Classified here into 9 main families, most of the 20 approved cytokine preparations (18 different cytokines; 3 pegylated), all in recombinant human (rh) form, are grouped in the hematopoietic growth factor, interferon, platelet-derived growth factor (PDGF) and transforming growth factor β (TGFβ) families. In the hematopoietin family, approved cytokines are aldesleukin (rhIL-2), oprelvekin (rhIL-11), filgrastim and tbo-filgrastim (rhG-CSF), sargramostim (rhGM-CSF), metreleptin (rh-leptin) and the rh-erythropoietins, epoetin and darbepoietin alfa. Anakinra, a recombinant receptor antagonist for IL-1, is in the IL-1 family; recombinant interferons alfa-1, alfa-2, beta-1 and gamma-1 make up the interferon family; palifermin (rhKGF) and becaplermin (rhPDGF) are in the PDGF family; and rhBMP-2 and rhBMP-7 represent the TGFβ family. The main physicochemical features, FDA-approved indications, modes of action and side effects of these approved cytokines are presented. Underlying each adverse events profile is their pleiotropism, potency and capacity to release other cytokines producing cytokine 'cocktails'. Side effects, some serious, occur despite cytokines being endogenous proteins, and this therefore demands caution in attempts to introduce individual members into the clinic. This caution is reflected in the relatively small number of cytokines currently approved by regulatory agencies and by the fact that 14 of the FDA-approved preparations carry warnings, with 10 being black box warnings.

Interferon-α is not elevated in idiopathic thrombotic thrombocytopenic purpura patients

Idiopathic thrombotic thrombocytopenic purpura (TTP) patients have ADAMTS13 deficiency, which is usually caused by ADAMTS13 autoantibodies. However, the triggering factors for the autoantibody production remain unclear. Interferon-α (IFN-α) is a cytokine involved with many autoimmune processes such as inducing the activation of peripheral dendritic cells and stimulating T cells and B cells. It also plays an important role in some autoimmune diseases. Elevated IFN-α levels have been observed in some TTP patients and previous case reports have shown the occurrence of TTP after IFN-α treatment. Thus, we hypothesized that high levels of IFN-α would correlate with presence of ADAMTS13 autoantibodies. However, we did not observe elevated IFN-α levels in 36 TTP patients (mean 5.29 pg/ml, standard deviation (SD) 26.56 pg/ml) compared to healthy controls (mean 0 pg/ml, SD 0 pg/ml), P = 0.59. IFN-α levels of most patients (94%) were undetectable. Only two patients had increased IFN-α levels and ADAMTS13 autoantibodies were detected in these two patients. Interestingly, both the patients had an underlying autoimmune disease. Although there have been cases of secondary TTP following IFN-α treatment, no evidence supports a role of IFN-α in the development of idiopathic TTP in our patient population.

Thrombotic microangiopathy in Interferon Beta treated multiple sclerosis patients: Review of literature and report of two new cases

Beta interferons (IFN-β) were the first approved disease modifying therapies (DMTs) for relapsing-remitting multiple sclerosis (RRMS) and are still the most-widely prescribed medications for this disease. Despite good overall long-term safety data with prolonged use of this group of drugs, they can rarely cause serious and sometimes life threatening adverse effects. In this article we report two cases of thrombotic microangiopathy occurring during prolonged use of IFN-β and review the available literature on this topic.

Renal thrombotic microangiopathy caused by interferon beta-1a treatment for multiple sclerosis

Interferon beta-1a is available as an immunomodulating agent for relapsing forms of multiple sclerosis. Common side effects include flu-like symptoms, asthenia, anorexia, and administration site reaction. Kidney disorders are rarely reported. In this study we describe the case of a woman who has been undergoing treatment with interferon beta-1a for multiple sclerosis for 5 years. She developed a hemolytic-uremic syndrome with intravascular hemolysis in a context of severe hypertension. A kidney biopsy showed a thrombotic microangiopathy. This observation highlights an uncommon side effect of long-term interferon beta-1a therapy. Pathophysiological mechanisms leading to this complication might be explained by the antiangiogenic activity of interferon.

Thrombotic microangiopathy due to acquired ADAMTS13 deficiency in a patient receiving interferon-beta treatment for multiple sclerosis

Thrombotic microangiopathies (TMAs) can be due to inherited or acquired ADAMTS13 deficiency. Acquired deficiency is mainly associated with autoantibodies directed to ADAMTS13, including drug-induced forms. A few cases of TMA have been reported in association with interferon-alpha treatment and more rarely with interferon-beta. We report the case of a 52-year-old male with TMA-associated severe renal failure secondary to severe ADAMTS13 deficiency due to an anti-ADAMTS13 IgG antibody which developed after interferon-beta treatment for multiple sclerosis. Treatment included interferon-beta discontinuation, immediate plasma exchange therapy, corticosteroids, and hemodialysis. After an initial hematologic improvement, early hemolysis relapse led us to introduce rituximab allowing durable hematologic recovery. This is the first reported case of interferon-beta-induced TMA due to acquired ADAMTS13 deficiency that was treated by rituximab.

Development of ocular myasthenia during pegylated interferon and ribavirin treatment for chronic hepatitis C

A 63-year-old male experienced sudden diplopia after 9 weeks of administration of pegylated interferon (IFN) alpha-2b and ribavirin for chronic hepatitis C (CHC). Ophthalmologic examinations showed ptosis on the right upper lid and restricted right eye movement without any other neurological signs. A brain imaging study and repetitive nerve stimulation test indicated no abnormality. The acetylcholine receptor antibody titer and response to acetylcholinesterase inhibitors were negative, and the results of thyroid function tests were normal. The patient's ophthalmological symptoms improved rapidly 3 weeks after discontinuation of pegylated IFN alpha-2b and ribavirin. The ocular myasthenia associated with combination therapy of pegylated IFN alpha-2b and ribavirin for CHC is very rarely reported; therefore, we present this case with a review of the various eye complications of IFN therapy.

Late Mortality from Thrombotic Microangiopathy After Liver Transplantation: Report of a Case

Thrombotic microangiopathy (TMA) after liver transplantation is thought to be a rare event. We report a case of TMA after living donor liver transplantation for hepatitis C virus-related cirrhosis. The patient was initially placed on a tacrolimus-based immunosuppressive regimen, and received combined ribavirin and interferon treatment as pre-emptive therapy for hepatitis C virus. His post-transplantation course was complicated by cytomegalovirus (CMV) antigenemia, and intra-abdominal hemorrhage after percutaneous liver biopsy, necessitating laparotomy. On postoperative day (POD) 53, we noted a marked thrombocytopenia with a sudden rise in lactate dehydrogenase. Blood smear indicated prominent fractionated erythrocytes. Treatment included immediate conversion from tacrolimus to cyclosporine (CsA) and successive plasma exchange (PE), despite which the TMA progressed. CsA was discontinued 32 days after initiating the PE, and the TMA progression seemed to cease. However, the patient's condition deteriorated and he died of multiple organ failure on POD 119. We report this case to stress that careful management of calcineurin inhibitor administration is critical in TMA.

Syndrome hémolytique et urémique et ischémie mésentérique aiguë lors d’un traitement par interféron alpha-2b pour une maladie de Kaposi associée au VIH

BACKGROUND

Interferon alpha is approved for the treatment of Kaposi's sarcoma in HIV infected patients. Hemolytic and uremic syndrome (HUS) is a rare side-effect of interferon alpha and has been reported primarily in chronic myelogenous leukemia.

CASE REPORT

A 44-year-old HIV-infected woman from Cameroon was admitted for treatment of cutaneous Kaposi's sarcoma. Two days later, she presented severe HUS. Abdominal pains subsequently revealed non-occlusive mesenteric ischemia. The patient rapidly improved after interferon withdrawal.

DISCUSSION

To our knowledge this is the first case of HUS induced by interferon alpha given for Kaposi's sarcoma. Further, no cases of acute mesenteric ischemia have been reported with interferon alpha. It is possible that the condition may have been induced or aggravated by HUS or a low infusion rate. Interferon can exert vascular toxicity on both the mesenteric vessels and the renal vessels in a setting of microangiopathy.

A case of deep venous thrombosis associated with pegylated interferon alpha2b plus ribavirin treatment of chronic hepatitis C

We present a case of deep venous thrombosis (DVT) during pegylated interferon (peg-IFN)-alpha2b plus ribavirin treatment of chronic hepatitis C (CHC). A 67-year-old man, who had been under treatment for hypertension and diabetes mellitus, was admitted to our hospital for peg-IFN-alpha2b plus ribavirin treatment for CHC. His serum hepatitis C virus (HCV) RNA level became undetectable 1 week after the initiation of peg-IFN-alpha2b plus ribavirin treatment. He suffered from severe pain, flare, and edema in both of his lower legs 6 weeks after the initiation of peg-IFN-alpha2b plus ribavirin treatment. He was diagnosed as having DVT because of the presence of a thrombus in the right soleus vein by ultrasonography. Peg-IFN-alpha2b plus ribavirin treatment was discontinued because a causal relationship between DVT and peg-IFN-alpha2b plus ribavirin treatment was suspected. DVT was not observed and the symptoms in both of his legs were improved after the administration of warfarin potassium. Subsequently, DVT has not recurred, and he has remained HCV-RNA negative.

The changing epidemiology of acute renal failure

Different definitions of acute renal failure (ARF) abound. The existence of multiple definitions makes it difficult to determine the true epidemiological characteristics of this condition. Despite this difficulty, it has been possible to detect notable variations in the epidemiology of ARF during the past few decades. The absolute incidence of ARF has increased, while associated mortality rate has remained relatively static. Several factors have contributed to this altered epidemiology. Here, we discuss the relative contribution of these factors, which include site of disease onset (developed or developing countries, community or hospital or intensive care unit), patient age, infections (HIV, malaria, leptospirosis and hantavirus), concomitant illnesses (cardiopulmonary failure, hemato-oncological disease), and interventions (hematopoietic progenitor cell and solid organ transplantation).

Von Willebrand factor-cleaving protease activity remains at the intermediate level in thrombotic thrombocytopenic purpura

A 59-year-old woman, diagnosed with chronic myelogenous leukemia (chronic phase) and treated with interferon-alpha for 13 years, developed renal failure. Renal biopsy showed thrombotic thrombocytopenic purpura, but intensive therapy including plasma exchange and steroid administration was not effective. The activity of von Willebrand factor-cleaving protease was detectable at the intermediate level (15-46%) during the clinical course, suggesting that this case was not compatible with the previously reported pattern of idiopathic or drug-induced thrombotic thrombocytopenic purpura, but with the pattern associated with malignant disease or immunological disorders. Further studies to determine the effects of interferon-alpha on endothelial cells in chronic myelogenous leukemia patients are needed.

Renal histopathological lesions after orthotopic liver transplantation (OLT)

Liver transplant recipients are at risk of chronic renal failure (CRF), customarily considered to be secondary to CsA/FK506 nephrotoxicity. We have examined renal biopsies from 26 liver transplant recipients with CRF. Before OLT, 5 patients had CRF, 8 were diabetic and 9 hypertensive. Renal biopsies were performed at a mean of 5 years after liver transplantation. Mean SCr was then 212 micromol/L, proteinuria was 1 g/24 h. Twelve patients were diabetic and 25 hypertensive. Histology revealed impressive renal destruction, with a mean of 45% interstitial fibrosis and 45% glomerular sclerosis. All biopsies showed severe arteriosclerosis. CRF can be attributed to four associated primary lesions: (i) specific chronic CsA/FK506 arteriolopathy; (ii) typical diabetic nephropathy; (iii) acute or chronic thrombotic microangiopathy attributed to CsA/FK506 or alpha-IFN and (iv) tubular changes related to administration of hydroxyethylstarch. At the end of the follow-up, after a mean of 6.4 years, 12 patients required dialysis, 13 had CRF and only 1 had normal renal function. Thus, CRF in OLT recipients is more complex than originally thought and should not be classified as anti-calcineurin nephrotoxicity without further investigations, including renal histology. These investigations have therapeutic potential, that is, they may lead to a more aggressive treatment of hypertension and/or diabetes.

Toxicité rénale des anticancéreux

Nephrotoxicity is an inherent adverse effect of certain anticancer drugs. Anti neoplasic drugs have a narrow therapeutic index and the amount of drug necessary to produce a significant reduction in tumour burden usually produces significant nephrotoxicity. The dosage used in clinical trials represents often the maximum tolerated doses determined during phase I drug evaluation. Greater toxicity is acceptable during curative therapy than during palliative therapy. But cancer patients often exhibit excretory reduced organ function. Modulation of pharmacokinetics and pharmacodynamics of these drugs in cancer patients is therefore necessary in order to improve tolerance. Patients with malignancies are particularly vulnerable to development of renal abnormalities. Conversely, patients with renal abnormalities who have undergone kidney transplantation are at high risk for malignancy. Clinical syndromes of renal involvement are diverse and sometimes insidious. Despite the recent advances in understanding the mechanism of anticancer drug nephrotoxicity, prevention still relies on drug dosage decrease and active screening for renal abnormalities as part of the usual biological work up in patients treated with anticancer drugs.

Visual side effects of pegylated interferon during therapy for chronic hepatitis C infection

Ocular toxicity, including retinopathy, optic neuropathy and ocular loss, has been infrequently (<1%) reported as a potentially serious adverse event associated with standard interferon therapy. The new pegylated interferons have improved pharmacokinetics which translates to better antiviral efficacy, however, this improved pharmacokinetic profile also has the potential to alter the frequency and extent of their adverse events. We describe a case of chronic hepatitis C infection that developed visual complaints after one month of pegylated interferon, and retinopathy confirmed on ophthalmologic examination. We place our report in context with a review of the literature related to visual complications associated with interferon therapy. From our compilation of case reports, it is apparent that variable doses and duration of interferon therapy have been associated with ocular toxicity, which in turn suggests an idiosyncratic drug reaction. In as much as this adverse event is unpredictable, and its frequency undefined with pegylated interferon therapy, further surveillance will be required for patients undergoing pegylated-interferon therapy. Although ocular toxicity is uncommon, it should be emphasized that it can occur any time after the start of interferon therapy, and physicians now treating chronic hepatitis C patients with pegylated interferon must be aware of this potentially serious adverse event.

Hepatitis C virus-related cryoglobulinemic glomerulonephritis: long-term remission after antiviral therapy

BACKGROUND

Renal involvement in patients with hepatitis C virus (HCV) infection commonly manifests as cryoglobulinemic glomerulonephritis (CGN). The combination of interferon-alpha (IFN-alpha) and ribavirin, which is currently considered the standard antiviral therapy in chronic hepatitis C, could be difficult to carry out in cryoglobulinemic patients who are frequently anemic, even in the absence of renal failure. Clinical and histologic long-term results of this therapeutic regimen have not been so far reported in patients with CGN.

METHODS

Three patients with HCV-related CGN and slightly impaired kidney function were treated with IFN-alpha and ribavirin for 12 months, and subsequently were followed up for 24 to 36 months. Two of these patients who were anemic were pretreated with erythropoietin (EPO). In each patient renal biopsy was performed before starting therapy and repeated 14 to 26 months after the end of treatment.

RESULTS

In all three patients, antiviral therapy induced sustained virologic response, which was followed by clear improvement in clinical, biochemical, immunologic, and histologic features. Clinical and biochemical improvement steadily progressed in all three patients, achieving normal or nearly normal results at the end of follow-up. In contrast, some immunologic features, such as serum levels of C4 and rheumatoid factor activity, did not normalize in two and three patients, respectively. Posttreatment renal biopsies showed mildly active histologic lesions.

CONCLUSION

Antiviral therapy with IFN-alpha and ribavirin may be considerably beneficial in patients with HCV-related CGN who obtain sustained virologic response.