Posttransplantation thrombotic thrombocytopenic purpura: a single-center experience and a contemporary review

Von Willebrand Factor and Platelet Levels before Conditioning Chemotherapy Indicate Bone Marrow Regeneration following Autologous Hematopoietic Stem Cell Transplantation

Autologous hematopoietic stem cell transplantation (HSCT) is often complicated by hemostatic and thrombotic events associated with endothelial cell injury. Thrombotic complications are affected by a disturbed balance between platelets, circulating von Willebrand factor (VWF), and its specific protease, ADAMTS13. HSCT-associated endothelial dysfunction, impaired hemostasis, and inflammation are interrelated processes, and research on the complex interplay of conditioning regimens from engraftment to bone marrow regeneration remains intensive. This prospective observational study comparing lymphoma and multiple myeloma (MM) patients who underwent autologous HSCT explored how platelet count, VWF level, ADAMTS13 activity, and C-reactive protein (CRP) level as potential markers (1) vary in response to therapy, (2) differ between the 2 groups, and (3) correlate with the remission state at 100 days after HSCT. We correlated the quantitative changes in platelet count and levels of VWF, ADAMTS13, and CRP with one another during HSCT and in the remission state in 45 patients with lymphoma and 59 patients with MM who underwent autologous HSCT between 2010 and 2013 at the University of Debrecen. Samples were collected at the start of conditioning chemotherapy, on the day of stem cell transplantation, and at 5, 11, and 100 days following HSCT. CRP levels peaked when platelet counts dropped to a minimum, and these changes were much more pronounced in the lymphoma group. VWF level was the highest, with lower ADAMTS13 activity, at platelet engraftment in both patient groups equally. Diagnostic evidence indicative of thrombotic complications was not found. In the lymphoma group, VWF level prior to conditioning had statistically significant correlations with platelet count, CRP level, and hemoglobin concentration at the time of bone marrow regeneration (P < .001) and during the remission state (P = .034). In the MM group, platelet count before conditioning was correlated with platelet count (P < .001) and white blood cell count (P = .012) at the time of bone marrow regeneration. The statistically significant correlation of the markers at the time of bone marrow regeneration with the preconditioning VWF levels in lymphoma and with the preconditioning platelet counts in MM might indicate the clinical significance of the bone marrow niches of arterioles and megakaryocytes, respectively, where the stem cells are located and regulated. Because preconditioning VWF levels are associated with remission after HSCT in lymphoma patients, VWF should be screened before conditioning, along with the markers used in HSCT protocols, to optimize personalized treatment and reduce therapeutic risks.

Molecular Pathogenesis of Endotheliopathy and Endotheliopathic Syndromes, Leading to Inflammation and Microthrombosis, and Various Hemostatic Clinical Phenotypes Based on "Two-Activation Theory of the Endothelium" and "Two-Path Unifying Theory" of Hemostasis

Endotheliopathy, according to the “two-activation theory of the endothelium”, can be triggered by the activated complement system in critical illnesses, such as sepsis and polytrauma, leading to two distinctly different molecular dysfunctions: (1) the activation of the inflammatory pathway due to the release of inflammatory cytokines, such as interleukin 6 and tumor necrosis factor-α, and (2) the activation of the microthrombotic pathway due to the exocytosis of hemostatic factors, such as ultra-large von Willebrand factor (ULVWF) multimers and FVIII. The former promotes inflammation, including inflammatory organ syndrome (e.g., myocarditis and encephalitis) and multisystem inflammatory syndrome (e.g., cytokine storm), and the latter provokes endotheliopathy-associated vascular microthrombotic disease (VMTD), orchestrating thrombotic thrombocytopenic purpura (TTP)-like syndrome in arterial endotheliopathy, and immune thrombocytopenic purpura (ITP)-like syndrome in venous endotheliopathy, as well as multiorgan dysfunction syndrome (MODS). Because the endothelium is widely distributed in the entire vascular system, the phenotype manifestations of endotheliopathy are variable depending on the extent and location of the endothelial injury, the cause of the underlying pathology, as well as the genetic factor of the individual. To date, because the terms of many human diseases have been defined based on pathological changes in the organ and/or physiological dysfunction, endotheliopathy has not been denoted as a disease entity. In addition to inflammation, endotheliopathy is characterized by the increased activity of FVIII, overexpressed ULVWF/VWF antigen, and insufficient ADAMTS13 activity, which activates the ULVWF path of hemostasis, leading to consumptive thrombocytopenia and microthrombosis. Endothelial molecular pathogenesis produces the complex syndromes of inflammation, VMTD, and autoimmunity, provoking various endotheliopathic syndromes. The novel conceptual discovery of in vivo hemostasis has opened the door to the understanding of the pathogeneses of many endotheliopathy-associated human diseases. Reviewed are the hemostatic mechanisms, pathogenesis, and diagnostic criteria of endotheliopathy, and identified are some of the endotheliopathic syndromes that are encountered in clinical medicine.

New insights into risk factors for transplant-associated thrombotic microangiopathy in pediatric HSCT

This study aimed to identify a risk profile for development of transplant-associated thrombotic microangiopathy (TA-TMA) in children undergoing hematopoietic stem cell transplantation (HSCT). Between 2013 and 2016, 439 children underwent 474 HSCTs at 2 supraregional United Kingdom centers. At a median of 153 days post-HSCT, TA-TMA occurred among 25 of 441 evaluable cases (5.6%) with no evidence of center variation. Sex, underlying disease, intensity of the conditioning, total body irradiation-based conditioning, the use of calcineurin inhibitors, venoocclusive disease, and viral reactivation did not influence the development of TA-TMA. Donor type: matched sibling donor/matched family donor vs matched unrelated donor vs mismatched unrelated donor/haplo-HSCT, showed a trend toward the development of TA-TMA in 1.8% vs 6.1% vs 8.3%, respectively. Presence of active comorbidity was associated with an increased risk for TA-TMA; 13% vs 3.7% in the absence of comorbidity. The risk of TA-TMA was threefold higher among patients who received >1 transplant. TA-TMA rates were significantly higher among patients with acute graft-versus-host disease (aGVHD) grades III to IV vs aGVHD grade 0 to II. On multivariate analysis, the presence of active comorbidity, >1 transplant, aGVHD grade III to IV were risk factors for TA-TMA (odds ratio [OR]: 5.1, 5.2, and 26.9; respectively), whereas the use of cyclosporine A/tacrolimus-based GVHD prophylaxis was not a risk factor for TA-TMA (OR: 0.3). Active comorbidity, subsequent transplant, and aGVHD grades III to IV were significant risk factors for TA-TMA. TA-TMA might represent a form of a vascular GVHD, and therefore, continuing control of aGVHD is important to prevent worsening of TA-TMA associated with GVHD.

Guidelines on the Use of Therapeutic Apheresis in Clinical Practice-Evidence-Based Approach from the Writing Committee of the American Society for Apheresis: The Seventh Special Issue

The American Society for Apheresis (ASFA) Journal of Clinical Apheresis (JCA) Special Issue Writing Committee is charged with reviewing, updating, and categorizing indications for the evidence-based use of therapeutic apheresis in human disease. Since the 2007 JCA Special Issue (Fourth Edition), the Committee has incorporated systematic review and evidence-based approaches in the grading and categorization of apheresis indications. This Seventh Edition of the JCA Special Issue continues to maintain this methodology and rigor to make recommendations on the use of apheresis in a wide variety of diseases/conditions. The JCA Seventh Edition, like its predecessor, has consistently applied the category and grading system definitions in the fact sheets. The general layout and concept of a fact sheet that was used since the fourth edition has largely been maintained in this edition. Each fact sheet succinctly summarizes the evidence for the use of therapeutic apheresis in a specific disease entity. The Seventh Edition discusses 87 fact sheets (14 new fact sheets since the Sixth Edition) for therapeutic apheresis diseases and medical conditions, with 179 indications, which are separately graded and categorized within the listed fact sheets. Several diseases that are Category IV which have been described in detail in previous editions and do not have significant new evidence since the last publication are summarized in a separate table. The Seventh Edition of the JCA Special Issue serves as a key resource that guides the utilization of therapeutic apheresis in the treatment of human disease. J. Clin. Apheresis 31:149-162, 2016. © 2016 Wiley Periodicals, Inc.

Treatment of thrombotic microangiopathy after hematopoietic stem cell transplantation with recombinant human soluble thrombomodulin

BACKGROUND

Transplant-associated thrombotic microangiopathy (TA-TMA) after hematopoietic stem cell transplantation (HSCT) remains a severe complication associated with underlying endothelial damage. TMA has a high mortality rate with no definite treatments and effective treatments are needed.

STUDY DESIGN AND METHODS

The study objective was to retrospectively analyze the outcome of patients receiving recombinant human soluble thrombomodulin (rTM), which has cytoprotective effects against calcineurin inhibitor-induced endothelial cell damage, or other therapeutics for TA-TMA from 254 consecutive HSCT recipients between 2009 to 2014 at a single institution. We hypothesized that patients receiving rTM as a first-line treatment would receive a benefit.

RESULTS

Sixteen patients were diagnosed as TA-TMA. Of these 16 patients, nine were treated with rTM (rTM group), and seven received treatment other than rTM (control group) as a first-line therapy. Seven of the nine patients in the rTM group recovered from TA-TMA without complications, but none in the control group recovered. The rTM group showed a significantly better overall survival after TA-TMA onset than did the control group (median, 123.0 days vs. 45.5 days, respectively; p = 0.045). The cumulative incidence of acute graft-versus-host disease was the same in both groups (56% vs. 57%, respectively; p = 0.52) on Day 100 after TA-TMA onset.

CONCLUSION

This is the first report evaluating rTM administration for TA-TMA compared with previous treatments. Our data suggests that rTM might offer a better clinical outcome in patients with TA-TMA.

Idiopathic Relapsing Thrombotic Thrombocytopenic Purpura with Persistent ADAMTS13 Inhibitor Activity Treated Sequentially with Plasmapheresis, Rituximab, Cyclophosphamide and Splenectomy

We here describe a patient with an idiopathic thrombotic thrombocytopenic purpura (TTP) secondary to an ADAMTS13 inhibitor that continued to be dependent on plasmapheresis until the patient was treated with rituximab. TTP manifestations subsided with rituximab treatment in spite of a persistently low ADAMTS13 activity and continued a detectable inhibitor activity until the patient developed an intolerance to rituximab due to an allergic reaction when cyclophosphamide was added; this resulted in a normalization of ADAMTS13 activity and the disappearance of the inhibitor. Later, the patient developed an intolerance to rituximab due to a severe allergic reaction. Soon after stopping rituximab, the ADAMTS13 activity level dipped below 5% in addition to the appearance of the ADAMTS13 inhibitor. The patient had a splenectomy after rituximab and cyclophosphamide treatment; the medication was stopped based on several case reports of a complete remission of TTP after splenectomy. We believe that the reason TTP went into remission in our patient was because of rituximab treatment, in spite of both persistently low ADAMTS13 activity and a detectable inhibitor activity due to reducing the release of von Willebrand factor large multimers from the endothelial cells. We found that ADAMTS13 activity normalized and the inhibitor activity became undetectable when cyclophosphamide was added to rituximab. We suggest adding cyclophosphamide to rituximab for the treatment of patients with persistent ADAMTS13 inhibitors in order to prolong the remission period and lower the rate of relapse.

A case of transplantation-associated thrombotic microangiopathy with cardiac involvement successfully treated with plasma exchange

Transplantation-associated thrombotic microangiopathy (TA-TMA) is occasionally described as a serious complication after allogeneic and, more rarely, autologous stem cell transplantation (SCT). It is characterized by poor outcome with high mortality rate. Plasma exchange (PE) has been reported as successful first-line therapy in other thrombotic microangiopathies. However, unlike to idiopathic forms, response to PE are usually suboptimal in TA-TMA and the use of PE remains controversial, because the exact mechanism of injury is not yet understood. The kidney is the most commonly affected organ and injury has rarely been reported elsewhere in the body, such as in lungs and gastrointestinal tract. Although several case reports have documented myocardial infarctions in patients presenting classic thrombotic thrombocytopenic purpura (TTP), there are no reports documenting cardiac involvement in TA-TMA. We describe a case of a 66-year-old man who experienced TA-TMA accompanied by cardiac ischemia after autologous SCT for multiple myeloma, successfully treated with PE. The immediate start of PE induced a complete remission of TA-TMA and disappearance of cardiac ischemic signs and symptoms except of a residual chronic renal failure.

Hematopoietic stem cell transplantation: graft versus host disease and pathology of gastrointestinal tract, liver, and lung

Hematopoietic stem cell transplantation (HCT), formerly known as bone marrow transplantation, is an integral part of treatment for many hematological malignancies. HCT is associated with several complications and comorbidities with differential effects on a wide spectrum of organs and tissues. We present an update on HCT-associated complications such as graft versus host disease (GVHD) and infection, with focus on the surgical pathology of the gastrointestinal (GI) tract, liver, and lung. Although the grading system for GI tract acute GVHD was proposed 40 years ago, recent studies have shed light on minimal histologic criteria for diagnosis of GVHD, as well as its differential diagnosis, including histologic effects of various medications. GI dysfunction in autologous transplant recipients is increasingly appreciated and patients are often biopsied. Acute liver injury in HCT is often due to sinusoidal obstruction syndrome (previously known as venoocclusive disease), or acute GVHD. Liver dysfunction at later time posttransplantation may be associated with acute or chronic GVHD, iron overload, or other causes of hepatitis. Lung injury in HCT is multifactorial, and it remains crucially important to diagnose and treat pulmonary infections. The pulmonary biopsy yields clinically unsuspected diagnoses in the majority of cases and its utilization is likely to increase. The pathology of the skin and kidney in HCT patients are detailed in accompanying articles.

Acquired thrombotic thrombocytopenic purpura in children: a single institution experience

OBJECTIVE

To describe the clinical features, treatment and prognosis of acquired thrombotic thrombocytopenic purpura (TTP) in children based on a single institution experience.

METHODS

This study is a retrospective review of all 12 children with TTP seen at New York Medical College- Westchester Medical Center during a period of 15 y from 1993 to 2008.

RESULTS

There were 7 females and 5 males with acquired TTP, with a median age of 13 (range, 6-17); and no cases of congenital TTP. The classic pentad of TTP (microangiopathic hemolytic anemia, thrombocytopenia, neurologic symptoms, renal dysfunction and fever) was seen in only three patients. Nine had renal involvement; eight had neurologic symptoms; and four had fever. All 12 patients had thrombocytopenia, anemia, and elevated LDH. Nine had idiopathic TTP. Three patients had one of the following underlying disorders: systemic lupus erythematosus, mixed connective tissue disorder, and aplastic anemia (post-bone marrow transplant on cyclosporine). ADAMTS13 level was decreased in 7 of 8 patients studied. Eight of 10 patients achieved remission with plasmapheresis alone. Two needed additional treatment before achieving remission. Two had one or more relapses, requiring immunosupressive treatment with vincrisine, prednisone, or rituximab. The patient with aplastic anemia died of pulmonary hypertension 5 y after bone marrow transplantation. All other 11 patients are alive and free of TTP for a median follow-up of 12 mo (range, 3-72 mo).

CONCLUSIONS

Acquired pediatric TTP responds well to plasmapheresis. However, many patients do require additional treatment because of refractoriness to plasmapheresis or relapse. The clinical features, response to treatment, and relapse rate of pediatric TTP appear similar to those of adult TTP.

Atypical thrombotic thrombocytopenic purpura in a middle-aged woman who presented with a recurrent stroke

An atypical clinical presentation makes TTP diagnosis difficult, which prevents prompt management of TTP. This case highlights the importance of early recognition of TTP in patients with atypical presentations who may not have the expected clinical or laboratory findings. The level of suspicion should be especially high in young and middle-aged patients with strokes or acute coronary syndrome who do not have other risk factors for cardiovascular events. This is particularly so for those patients who have a previous episode of TTP or patients with subtle laboratory abnormalities, which may suggest the potential existence of a thrombotic microangiopathic process.

Cyclosporin A impairs the secretion and activity of ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 repeat)

The protease ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 repeat) cleaves multimers of von Willebrand factor, thus regulating platelet aggregation. ADAMTS13 deficiency leads to the fatal disorder thrombotic thrombocytopenic purpura (TTP). It has been observed that cyclosporin A (CsA) treatment, particularly in transplant patients, may sometimes be linked to the development of TTP. Until now, the reason for such a link was unclear. Here we provide evidence demonstrating that cyclophilin B (CypB) activity plays an important role in the secretion of active ADAMTS13. We found that CsA, an inhibitor of CypB, reduces the secretion of ADAMTS13 and leads to conformational changes in the protein resulting in diminished ADAMTS13 proteolytic activity. A direct, functional interaction between CypB (which possesses peptidyl-prolyl cis-trans isomerase (PPIase) and chaperone functions) and ADAMTS13 is demonstrated using immunoprecipitation and siRNA knockdown of CypB. Finally, CypB knock-out mice were found to have reduced ADAMTS13 levels. Taken together, our findings indicate that cyclophilin-mediated activity is an important factor affecting secretion and activity of ADAMTS13. The large number of proline residues in ADAMTS13 is consistent with the important role of cis-trans isomerization in the proper folding of this protein. These results altogether provide a novel mechanistic explanation for CsA-induced TTP in transplant patients.

Cyclosporin A therapy on idiopathic thrombotic thrombocytopenic purpura in the relapse setting: two case reports and a review of the literature

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening disease, characterized by microangiopathic hemolytic anemia, thrombocytopenia, fever, neurologic disturbances, and renal failure. Plasma therapy has dramatically improved prognosis of TTP, whereas recurrent acute episodes still occur in approximately 40% of patients. Moreover, patients with acquired ADAMTS13 deficiency, which is a significant factor for relapse, may require additional immunosuppressive treatment to get a durable remission.

STUDY DESIGN AND METHODS

We hereby report two patients with a history of relapsed idiopathic TTP, who both received cyclosporin A (CSA) as a prophylactic manner after the remission was achieved. We also discuss the efficacy of CSA in patients with relapsed idiopathic TTP with a review of the published literature.

RESULTS

Under CSA therapy, both patients maintained their clinical remission state, and the ADAMTS13 levels were normalized.

CONCLUSION

To conclude, CSA therapy may be useful for the prevention of relapsed idiopathic TTP in patients with a history of frequent relapses.

The role of plasmapheresis in critical illness

In this article, the authors review the current recommendations from the American Society for Apheresis regarding the use of plasmapheresis in many of the diseases that intensivists commonly encounter in critically ill patients. Recent experience indicates that therapeutic plasma exchange may be useful in a wide spectrum of illnesses characterized by microvascular thrombosis, the presence of autoantibodies, immune activation with dysregulation of immune response, and some infections.

The TITAN trial--assessing the efficacy and safety of an anti-von Willebrand factor Nanobody in patients with acquired thrombotic thrombocytopenic purpura

The Phase II TITAN trial is designed to assess the efficacy and safety of an anti-von Willebrand factor (vWF) Nanobody in patients with acquired thrombotic thrombocytopenic purpura (TTP). Nanobodies are a novel class of therapeutic proteins and are based on the smallest functional fragments of single-chain antibodies that occur naturally in the Camelidae family (Nanobody® and Nanobodies® are registered trademarks of Ablynx NV). With vWF implicated in the thrombotic process underlying TTP, an anti-vWF Nanobody may hold significant promise as adjunctive therapy to plasma exchange. Recruitment is currently ongoing, and aims to include a total of 110 patients from countries in Europe, the Middle East, Australia and Northern America.

Novel recombinant glycosylphosphatidylinositol (GPI)-anchored ADAMTS13 and variants for assessment of anti-ADAMTS13 autoantibodies in patients with thrombotic thrombocytopenic purpura

Immunoglobulin Gs (IgGs) against ADAMTS13 are major causes of acquired (idiopathic) thrombotic thrombocytopenic purpura (TTP). We report here a novel cell-based assay using glycosylphosphatidylinositol (GPI)-anchored ADAMTS13 or variants expressed on cell membrane for assessment of autoantibodies in patients with TTP. We showed that IgGs from all 26 patients with acquired TTP bound to cells expressing a GPI anchored full-length ADAMTS13 (gFL) and a variant truncated after the spacer domain (gS). Also, IgGs from 25/26 (96.7%) of these TTP patients bound to cells expressing a GPI-anchored C-terminal fragment, TSP1 2-8 plus CUB (gT2C). In contrast, none of the 20 healthy blood donors showed detectable binding of their IgGs to the cells expressing gFL, gS, and gT2C. A moderate, but statistically significant correlation was observed between plasma concentrations of anti-ADAMTS13 IgG and positive cells expressing gFL (r=0.65), gS (r=0.67), and gT2C (r=0.42). These results suggest that the microtiter-plate assay and the cell-based assay may detect differential antigenic epitopes. Moreover, antigens clustered on cell membranes may enhance antibody binding affinity, thereby increasing analytical sensitivity. Finally, our assay was able to determine kinetic changes of plasma levels of anti-ADAMTS13 IgGs in TTP patients during plasma therapy. Together, our findings suggest that the novel cell-based assay may be applicable for rapid identification and mapping of anti-ADAMTS13 autoantibodies in patients with acquired TTP.

Renal thrombotic microangiopathy associated with chronic humoral graft versus host disease after hematopoietic stem cell transplantation

Thrombotic microangiopathy (TMA) is a known complication of hematopoietic stem cell transplantation (HSCT). The pathogenesis of TMA is controversial but considered to involve various factors such as total body irradiation, use of calcineurin inhibitors for prophylaxis against graft versus host disease (GVHD), viral infection, and GVHD. Herein we describe a case with renal TMA after HSCT, which was probably associated with antibody-mediated endothelial cell injury from chronic GVHD (termed here 'chronic humoral GVHD'). A 49-year-old man presented two years after HSCT with renal dysfunction and proteinuria but without the clinical features of TMA. Histopathological examination of renal biopsy showed chronic glomerular endothelial cell injury with double contour of the glomerular basement membrane, microthrombi and the deposition of complement split product C4d along the glomerular capillaries. Renal tubulitis and peritubular capillaritis were also noted with a multilayered basement membrane and patchy C4d deposition on peritubular capillaries. These findings resemble those of chronic antibody-mediated rejection after kidney transplantation. Furthermore, C4d deposition suggests complement activation. Although circulating anti-blood type and anti-human leukocyte antigen antibodies were not detected, the renal TMA in this case was probably associated with chronic humoral GVHD.

Thrombotic microangiopathy in haematopoietic cell transplantation: an update

Allogeneic hematopoietic cell transplantation (HCT) represents a vital procedure for patients with various hematologic conditions. Despite advances in the field, HCT carries significant morbidity and mortality. A rare but potentially devastating complication is transplantation-associated thrombotic microangiopathy (TA-TMA). In contrast to idiopathic TTP, whose etiology is attributed to deficient activity of ADAMTS13, (a member of the A Disintegrin And Metalloprotease with Thrombospondin 1 repeats family of metalloproteases), patients with TA-TMA have > 5% ADAMTS13 activity. Pathophysiologic mechanisms associated with TA-TMA, include loss of endothelial cell integrity induced by intensive conditioning regimens, immunosuppressive therapy, irradiation, infections and graft-versus-host (GVHD) disease. The reported incidence of TA-TMA ranges from 0.5% to 75%, reflecting the difficulty of accurate diagnosis in these patients. Two different groups have proposed consensus definitions for TA-TMA, yet they fail to distinguish the primary syndrome from secondary causes such as infections or medication exposure. Despite treatment, mortality rate in TA-TMA ranges between 60% to 90%. The treatment strategies for TA-TMA remain challenging. Calcineurin inhibitors should be discontinued and replaced with alternative immunosuppressive agents. Daclizumab, a humanized monoclonal anti-CD25 antibody, has shown promising results in the treatment of TA-TMA. Rituximab or the addition of defibrotide, have been reported to induce remission in this patient population. In general, plasma exchange is not recommended.

A case of pregnancy-induced thrombotic thrombocytopenic purpura with a kidney allograft recipient

A 32-yr-old female patient, who had been suffering from diffuse crescentic glomerulonephritis and a consequent end-stage renal disease, successfully underwent living-related ABO-incompatible kidney transplantation after a desensitization therapy including anti-CD20 monoclonal antibody. Forty-six months after the transplantation, the recipient became pregnant. At the 17th gestational week, the patient was admitted for the management of pregnancy-induced hypertension and aggressive deterioration of kidney graft function. At the 21st gestational week, the patient lost her kidney graft and was re-induced into regular hemodialysis. The patient was also suffering from progressive hemolytic anemia, thrombocytopenia, and neurologic symptoms with decreased activity of von Willebrand factor-cleaving protease, a disintegrin-like and metalloprotease with thrombospondin type 1 motifs 13 (ADAMTS13). From these findings and a kidney allograft biopsy, the patient was diagnosed as thrombotic thrombocytopenic purpura concurrent with acute T-cell-mediated rejection. The patient immediately underwent plasma exchange as well as steroid pulse therapy. Despite these treatments, thrombocytopenia and intrauterine growth retardation progressed. The patient underwent a caesarian section at the 24th gestational week. Consequently, her platelet count recovered drastically. However, the patient lost her neonate five d after giving a birth, and the patient's graft function had never recovered.

Guidelines on the use of therapeutic apheresis in clinical practice--evidence-based approach from the Apheresis Applications Committee of the American Society for Apheresis

The American Society for Apheresis (ASFA) Apheresis Applications Committee is charged with a review and categorization of indications for therapeutic apheresis. Beginning with the 2007 ASFA Special Issue (fourth edition), the subcommittee has incorporated systematic review and evidence-based approach in the grading and categorization of indications. This Fifth ASFA Special Issue has further improved the process of using evidence-based medicine in the recommendations by refining the category definitions and by adding a grade of recommendation based on widely accepted GRADE system. The concept of a fact sheet was introduced in the Fourth edition and is only slightly modified in this current edition. The fact sheet succinctly summarizes the evidence for the use of therapeutic apheresis. The article consists of 59 fact sheets devoted to each disease entity currently categorized by the ASFA as category I through III. Category IV indications are also listed.

Acute kidney injury in patients with systemic sclerosis participating in hematopoietic cell transplantation trials in the United States

Recipients of hematopoietic cell transplantation may be at risk for developing acute kidney injury (AKI), and this risk may be increased in patients who undergo transplantation for severe systemic sclerosis (SSc) due to underlying scleroderma renal disease. AKI after transplantation can increase treatment-related mortality. To better define these risks, we analyzed 91 patients with SSc who were enrolled in 3 clinical trials in the United States of autologous or allogeneic hematopoietic cell transplantation (HCT). Eleven (12%) of the 91 patients with SSc in these studies (8 undergoing autologous HCT, 1 undergoing allogeneic HCT, 1 pretransplantation, 1 given i.v. cyclophosphamide on a transplantation trial) experienced AKI, of whom 8 required dialysis and/or therapeutic plasma exchange. AKI injury in the 9 HCT recipients developed a median of 35 days (range, 0-90 days) after transplantation. Ten of 11 patients with AKI received angiotensin-converting enzyme inhibitor (ACE-I) therapy. The etiology of AKI was attributed to scleroderma renal crisis in 6 patients (including 2 with normotensive renal crisis), to AKI of uncertain etiology in 2 patients, and to AKI superimposed on scleroderma kidney disease in 3 patients. Eight of the 11 patients died, one each because of progression of SSc, multiorgan failure, gastrointestinal and pulmonary bleeding, pericardial tamponade and pulmonary complications, diffuse alveolar hemorrhage, pulmonary embolism, graft-versus-host disease, and malignancy. Limiting nephrotoxins, cautious use of corticosteroids, renal shielding during total body irradiation, strict control of blood pressure, and aggressive use of ACE-Is may be of importance in preventing renal complications after HCT for SSc.

Early clinical indicators of transplant-associated thrombotic microangiopathy in pediatric neuroblastoma patients undergoing auto-SCT

Patients undergoing auto-SCT for neuroblastoma present a unique population to study transplant-associated thrombotic microangiopathy (TA-TMA), due to standardized chemotherapy and later exposure to radiation and cis-retinoic acid (cis-RA). We retrospectively analyzed 20 patients after auto-SCT to evaluate early clinical indicators of TA-TMA. A total of 6 patients developing TA-TMA (30% prevalence) were compared with 14 controls. Four of six patients were diagnosed with TA-TMA by 25 days after auto-SCT. Compared with controls, TA-TMA patients had higher average systolic and diastolic blood pressure levels during high-dose chemotherapy and developed hypertension by day 13 after auto-SCT. Proteinuria was a significant marker for TA-TMA, whereas blood and platelet transfusion requirements were not. Serum creatinine did not differ between groups post transplant. However, patients with TA-TMA had a 60% decrease in renal function from baseline by nuclear glomerular filtration rate, compared with a 25% decrease in those without TA-TMA (P=0.001). There was no TA-TMA-related mortality. Significant complications included end-stage renal disease (n=1) and polyserositis (n=3). Patients with TA-TMA were unable to complete cis-RA therapy after auto-SCT. We suggest that careful attention to blood pressure and urinalysis will assist in the early diagnosis of TA-TMA, whereas serum creatinine seems to be an insensitive marker for this condition.

A kidney transplant patient on cyclosporine therapy presenting with dural venous sinus thrombosis: a case report

Dural vein thrombosis is an important but rare cause of headache. Therapy with cyclosporine has been reported to result in thrombotic events. We report an unusual case of superior sagittal and transverse sinus thrombosis associated with cyclosporine therapy in a kidney transplant patient.

Thrombotic thrombocytopenic purpura in childhood

Thrombotic thrombocytopenic purpura (TTP) is a rare disease, especially in childhood, and has a high mortality rate in the absence of appropriate treatment. It is characterised by microangiopathic haemolytic anaemia and consumptive thrombocytopenia. TTP may be difficult to distinguish from haemolytic uraemic syndrome (HUS) because of similar clinical manifestations and laboratory findings. In the past, TTP and HUS have often been considered to represent variable expressions of a single entity. Our increased understanding of the pathogenesis of TTP has in turn resulted in significant improvements in its treatment and outcomes. Several immunomodulating agents are currently being used with variable outcomes.

Posttransplant thrombotic microangiopathy: sensitivity of proposed new diagnostic criteria

BACKGROUND

Objective diagnosis of transplantation-associated thrombotic microangiopathy (TA-TMA) has traditionally been difficult due to the multiple potential etiologies of thrombocytopenia and red blood cell fragmentation occurring after allogeneic hematopoietic stem cell transplantation (SCT). To attempt to address this issue of diagnostic uncertainty, two new diagnostic criteria for TA-TMA have recently been proposed: the Bone Marrow Transplant Clinical Trials Network (BMT-CTN) and the International Working Group (IWG) criteria. However, both newly proposed criteria are yet to be clinically validated.

STUDY DESIGN AND METHODS

All 15 cases of TA-TMA previously diagnosed at the authors' institution between December 2001 and March 2008 were retrospectively reclassified under the newly proposed BMT-CTN and IWG criteria.

RESULTS

Potential diagnostic pitfalls were identified in both the BMT-CTN and the IWG TA-TMA criteria. The main limitation of the BMT-CTN criteria appeared to be need for concurrent renal and/or neurologic dysfunction to be manifest at TA-TMA diagnosis, which was present in only 73% of our patient cohort. For the IWG criteria, the main limitation to TA-TMA diagnosis appeared to be the requirement for schistocytosis of more than 4%, which was present in only 27% of these patients.

CONCLUSION

Our experience suggests that potentially significant diagnostic pitfalls remain with both recently proposed TA-TMA diagnostic criteria, pitfalls that are likely to limit the diagnostic sensitivity of both. It is recommended that further clinical correlation of both the BMT-CTN and the IWG criteria be undertaken before either is routinely adapted into SCT practice.

Thrombotic microangiopathy in haematopoietic stem cell transplantation: diagnosis and treatment

Each year in the US, more than 10 000 patients benefit from allogeneic haematopoietic stem cell transplantation (HSCT), a modality that offers an excellent chance of eradicating malignancy but confers a higher risk of treatment-related mortality. An uncommon but devastating consequence of HSCT is transplantation-associated thrombotic microangiopathy (TA-TMA). The incidence of TA-TMA ranges from 0.5% to 76%, with a mortality rate of 60-90% despite treatment. Although there appears to be a consistent treatment approach to idiopathic thrombotic thrombocytopenic purpura (TTP) using plasma exchange, corticosteroids and rituximab, the treatment strategies for TA-TMA are perplexing, in part, because the literature regarding this complex condition does not provide true consensus for incidence, aetiology, diagnostic criteria, classification and optimal therapy. The classic definition of idiopathic TTP includes schistocytes on the peripheral blood smear, thrombocytopenia and increased serum lactate dehydrogenase. Classic idiopathic TTP has been attributed to deficient activity of the metalloproteinase responsible for cleaving ultra-large von Willebrand factor multimers. This protease is a member of the 'a disintegrin and metalloprotease with thrombospondin type 1 motif' family and is subsequently named ADAMTS-13. Severely deficient ADAMTS-13 activity (<5% of normal) is associated with idiopathic TTP in 33-100% of patients. In constrast to the pathophysiology of idiopathic TTP, patients with TA-TMA have >5% ADAMTS-13 serum activity. These data may explain why plasma exchange, a standard treatment modality for idiopathic TTP that restores ADAMTS-13 activity, is not effective in TA-TMA. TA-TMA has a multifactorial aetiology of endothelial damage induced by intensive conditioning therapy, irradiation, immunosuppressants, infection and graft-versus-host disease. Treatment consists of substituting calcineurin inhibitors with an alternative immunosuppressive agent that possesses another mode of action. One candidate may be daclizumab, especially in those with mild to moderate TMA. Rituximab therapy or the addition of defibrotide may also be beneficial. In general, plasma exchange is not recommended.

ADAMTS13 activity levels in patients with human immunodeficiency virus-associated thrombotic microangiopathy and profound CD4 deficiency

BACKGROUND

Thrombotic microangiopathy (TMA) encompasses a number of disorders with hemolytic anemia and thrombocytopenia, including thrombotic thrombocytopenic purpura (TTP). A deficiency in ADAMTS13 enzyme levels, along with an inhibitory antibody, is found in most patients with idiopathic TTP. Patients with human immunodeficiency virus (HIV) infection can have a TTP-like illness; however, it appears to have a different etiology.

METHODS

A retrospective review of patients who had an ADAMTS13 activity level performed from 2005 through 2007 was completed. Patients with a diagnosis of HIV infection with TMA were investigated.

RESULTS

Two patients were identified. Case 1: a 47-year-old man with HIV infection and a CD4 count <10/microL presented with altered mental status, pneumonia, acute renal failure, thrombocytopenia, and anemia. The ADAMTS13 level was 71%. He was treated with plasma infusion. Two days after admission, he expired because of respiratory distress syndrome and metabolic lactic acidosis. Case 2: a 39-year-old man with HIV infection and a CD4 count of 9/microL presented with chest pain, acute renal failure, thrombocytopenia, and anemia. The ADAMTS13 level was 65%. He received multiple units of fresh frozen plasma without significant improvement in his platelet count. Six days after admission, the patient began highly active antiretroviral therapy, which resulted in a rapid increase in his platelet count.

CONCLUSIONS

HIV-associated TMA is postulated to have a different pathophysiology than idiopathic TTP. This study supports that assumption because both patients exhibited many of the classic findings of TTP but did not have a deficiency of ADAMTS13.

Is it HIV TTP or HIV-associated thrombotic microangiopathy?

Thrombocytopenia is a common complication of Human Immunodeficiency Virus (HIV) infection. With advanced HIV disease, the presence of both thrombocytopenia and schistocytosis are frequently observed. In such cases, the diagnosis of HIV associated TTP is often considered. This article reviews emerging concepts of HIV associated microangiopathies. It concludes that the pathophysiology, in many cases seems to be distinct from idiopathic TTP (particularly with advanced HIV disease-<100 CD4/microliter). A sine que non for successful therapy of HIV-TMA appears to be the treatment of the underlying HIV infection.

Plasma exchange therapy for thrombotic thrombocytopenic purpura in pediatric patients with liver transplantation

PURPOSE

Sporadic cases of thrombotic thrombocytopenic purpura (TTP) have been reported in bone marrow and solid organ transplant patients receiving cyclosporine (CsA). We reported our experience with TTP using plasma exchange (PE) therapy in patients with liver transplantation (OLT).

METHODS

Between March, 1993, and May, 2007, 400 patients underwent OLT, including 146 pediatric living-donor liver transplantation (LDLT). Four pediatric patients developed TTP after OLT: three were males and one female of mean age at the time of transplantation of 7.8 +/- 3.6 years. The four recipients had the following indications for OLT: two glycogen storage disease, one biliary atresia, and one fulminant hepatic failure. Four patients initially received triple drug immunosuppression consisting of CsA, azathioprine, and steroids.

RESULTS

Four (1%) patients developed TTP after OLT. All four patients were pediatric in the age group. The mean age at the time of TTP diagnosis was 8.0 +/- 3.2 years, with a mean postoperative interval to TTP of 78.8 +/- 114.2 days. The mean baseline platelet count was 7.0 +/- 7.1 x 10,000. The eventual platelet count was 21.1 +/- 20.8 x 10,000 after PE. These patients received PE 6.0 +/- 4.2. The mean baseline serum creatinine was 0.8 +/- 0.8 mg/dL. The mean peak serum creatinine was 2.3 +/- 2.3 mg/dL. The mean serum CsA level was 717.5 +/- 106.0 ng/mL before TTP diagnosis. Four patients were diagnosed by blood peripheral smears. The causes of TTP were CsA-associated in three patients and venoocclusive disease (VOD) in one patient. Three patients improved their platelet counts after PE therapy. Two patient changed from CsA to FK 506, one underwent reduced CsA dosage, and one stopped CsA. Three patients died of recurrent VOD, infection, and intrapulmonary hemorrhage. Only one patient survived.

CONCLUSIONS

The incidence of TTP in our series was lower. It only developed in pediatric patients. The causes of TTP were associated with CsA and/or VOD. The mortality was high after the TTP diagnosis. We concluded that TTP was a potentially fatal condition, but an early diagnosis with prompt institution of therapy with invasive PE therapy may reduce its mortal consequences.

Effect of prophylactic cyclosporine therapy on ADAMTS13 biomarkers in patients with idiopathic thrombotic thrombocytopenic purpura

Several reports have been published regarding the use of cyclosporine (CSA) in the treatment of idiopathic thrombotic thrombocytopenic purpura (TTP). We hypothesized that prophylactic CSA therapy may prevent recurrences in patients with a history of multiple relapses of TTP. Nineteen patients with idiopathic TTP were enrolled on prospective studies at Ohio State University between September 2003 and May 2007. Patients achieving remission remained on CSA therapy for 6 months, allowing us to evaluate the efficacy of CSA as prophylactic therapy. CSA was administered orally at a dose of 2-3 mg/kg in twice a day divided dose in all patients and continued for a total of 6 months. Long-term clinical follow-up with serial analysis of ADAMTS13 biomarkers during and after CSA therapy were performed to evaluate the efficacy of CSA as a prophylactic therapy. 17/19(89%) patients completed 6 months of CSA therapy in a continuous remission. Two patients relapsed during therapy with CSA and seven patients relapsed after discontinuing CSA therapy. Ten patients have maintained a continuous remission a median of 21 months (range, 5-46) after discontinuing CSA. The ADAMTS13 data suggest that CSA resulted in a significant increase in the ADAMTS13 activity during therapy with CSA. 8/9(89%) relapsing patients had severely deficient ADAMTS13 activity (<5%) suggesting this is a significant risk factor for relapse of TTP. These data support the hypothesis that prophylactic CSA improves the ADAMTS13 activity and may be effective at preventing relapses in patients at risk for recurrences of TTP.

Pathogenesis of thrombotic microangiopathies

Profound thrombocytopenia and microangiopathic hemolytic anemia characterize thrombotic microangiopathy, which includes two major disorders: thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS). TTP has at least three types: congenital or familial, idiopathic, and nonidiopathic. The congenital and idiopathic TTP syndromes are caused primarily by deficiency of ADAMTS13, owing to mutations in the ADAMTS13 gene or autoantibodies that inhibit ADAMTS13 activity. HUS is similar to TTP, but is associated with acute renal failure. Diarrhea-associated HUS accounts for more than 90% of cases and is usually caused by infection with Shiga-toxin-producing Escherichia coli (O157:H7). Diarrhea-negative HUS is associated with complement dysregulation in up to 50% of cases, caused by mutations in complement factor H, membrane cofactor protein, factor I or factor B, or by autoantibodies against factor H. The incomplete penetrance of mutations in either ADAMTS13 or complement regulatory genes suggests that precipitating events or triggers may be required to cause thrombotic microangiopathy in many patients.

Thrombotic microangiopathy after allogeneic hematopoietic stem cell transplantation: an autopsy study

BACKGROUND

Posttransplantation thrombotic microangiopathy (PTMA) is a complication of allogeneic hematopoietic stem cell transplantation (HSCT). However, limited autopsy data are available, and it remains unclear whether PTMA is a discrete clinical and pathologic entity. The aims of this autopsy study were to determine the correlation between clinical and pathologic diagnosis of PTMA, to define the precise morphologic spectrum of PTMA, and to seek for potential etiologic factors.

METHODS

The study included 20 consecutive patients with HSCT autopsied at the University of Oklahoma, between 1994 and 2005. Applying strict clinical-laboratory criteria, 6 patients were diagnosed clinically with PTMA and treated with plasma exchange. Clinical variables, including underlying disease, conditioning regimen, stem cell donor status, duration and serum level of cyclosporine, infections, and acute graft versus host disease were compared statistically in patients with histologic signs of PTMA (n=8) with those without PTMA (n=12).

RESULTS

PTMA was verified histologically in all 6 patients with a clinical diagnosis of PTMA but only 2 of the 14 patients who were not clinically diagnosed had histologic evidence of PTMA (P<0.0001). Kidneys were affected in all 8 patients with PTMA, and limited extrarenal involvement by PTMA was observed in 3 of these 8 patients. No statistically significant differences in relevant clinical and morphologic variables were identified between the PTMA and non-PTMA groups.

CONCLUSIONS

This study documents a strong correlation between the clinical and morphologic diagnosis of PTMA. The kidney is the primary target of PTMA, with dominant glomerular and arteriolar involvement. The etiology is likely to be multifactorial.

Cyclosporin and plasma exchange in thrombotic thrombocytopenic purpura: long-term follow-up with serial analysis of ADAMTS13 activity

We hypothesized that cyclosporin (CSA) as adjunct to plasma exchange (PE) improves the efficacy of PE in idiopathic thrombotic thrombocytopenic purpura (TTP) via suppression of the antibody inhibitor of ADAMTS13. Our preliminary findings with CSA and PE as the upfront treatment of TTP suggested that the addition of CSA to PE significantly decreased the exacerbation (disease recurrence within 30 d of the last PE) rates compared to a cohort that received corticosteroids and PE as their upfront therapy of TTP. We present an updated analysis with long-term follow-up of 18 patients with idiopathic TTP treated with concurrent CSA and PE with analysis of serial measurements of ADAMTS13 activity, antigen and inhibitor concentration in the context of clinical outcome data. Overall, 16/18 (89%) patients achieved remission, similar to historical remission rates in idiopathic TTP with PE with only one patient suffering an exacerbation. Clinical responses correlated with improvements in ADAMTS13 activity and suppression of the antibody inhibitor of ADAMTS13. These data suggest that the efficacy of CSA is at least in part related to its suppression of the antibody inhibitor of ADAMTS13 and a subsequent improvement in ADAMTS13 activity and antigen.

A case report of thrombotic thrombocytopenic purpura and severe acute renal failure post non-myeloablative allogeneic peripheral blood stem cell transplantation treated with plasma exchange and hemodialysis

A 59-year-old-woman received related non-myeloablative allogeneic peripheral blood stem cell transplantation (PBSCT) subsequent to autologous PBSCT in our hospital five years after she was diagnosed as oligo-secretory myeloma. She was admitted to our hospital because of vomiting and grayish diarrhea 4 months after non-myeloablative allogeneic PBSCT (mini-alloPBSCT). Although her initial symptoms improved after admission, she gradually showed thrombocytopenia, anemia, and oliguria during the 2 weeks after admission. Our diagnosis was thrombotic thrombocytopenic purpura (TTP) and acute renal failure (ARF) secondary to mini-alloPBSCT. After cessation of cyclosporine administration, we began to treat her with plasma exchange (PE) and hemodialysis. During the three and a half months after we started PE, the TTP gradually improved. Although PE had been reported to be ineffective for TTP post bone marrow transplantation, we could finally discontinue PE. In contrast, since her anuria continued, she was managed with hemodialysis. One month after PE was started, her activity of von Willebrand factor-cleaving protease was 41% (normal range, >50%) and the ultrasonographic investigation of both kidneys was normal. She could be discharged after four and a half months hospitalization and lived well as an outpatient for a further two months. She died shortly after readmission from multiple organ failure without the relapse of TTP. The patient's clinical course would suggest that TTP post mini-alloPBSCT could be treated with PE in some cases, despite the development of dialysis-requiring severe ARF being a poor prognostic factor.

The thrombotic microangiopathies

The term thrombotic microangiopathy (TMA) encompasses a group of conditions that are defined by, or result from, a similar histopathological lesion. Hemolytic uremic syndrome (HUS), thrombotic thrombocytopenic purpura (TTP), and several other conditions are associated with TMA. Distinguishing HUS from TTP is not always possible unless there are specific causes, such as Shiga toxin, Streptococcus pneumoniae, or a specific molecular defect such as factor H or ADAMTS13 deficiency. This review describes the forms of HUS/TTP that are not related to Shiga toxin, pneumococcal infection, genetic causes, or ADAMTS13 deficiency. Conditions include HUS/TTP associated with autoimmune disorders, human immunodeficiency virus (HIV) infection, transplantation, malignancy, and medications.

Diagnosis and treatment of transplantation-associated thrombotic microangiopathy: real progress or are we still waiting?

Transplantation-associated thrombotic microangiopathy (TA-TMA) is an infrequent but devastating syndrome that occurs in allogeneic hematopoietic stem cell transplant recipients, and is associated with a variety of transplantation-related factors, including conditioning regimens, immunosuppressive agents, GVHD and opportunistic infections. Progress in managing this condition has been hampered by lack of a consensus definition and poor understanding of the pathophysiology of the disorder. Two different groups recently have proposed consensus definitions, yet they fail to distinguish the primary syndrome from the secondary causes, such as a variety of infections, medication exposure or other conditions. Increasing evidence suggests that TA-TMA is a multifactorial disorder that is distinct from thrombotic thrombocytopenic purpura (TTP), and likely represents the final common pathway of a number of endothelial cell insults. TA-TMA responds poorly to conventional treatment for TTP, including plasma exchange, but newer agents, including daclizumab and defibrotide show promise. In addition, other agents known to modify endothelial responses to injury, including statins, prostacyclin analogues, endothelin-receptor antagonists and free radical scavengers, may lead to improved outcomes for patients affected by this disorder.

Thrombotic microangiopathy following allogeneic hematopoietic stem cell transplantation

PURPOSE OF REVIEW

The aim of this article is to assess the current understanding and uncertainties about the evaluation and management of thrombotic microangiopathy that occurs following allogeneic hematopoietic stem cell transplantation.

RECENT FINDINGS

Current data may not be sufficient to establish posttransplantation thrombotic microangiopathy as a discrete clinical or pathologic entity, distinct from other well recognized transplant-related complications. Analysis of case series of posttransplantation thrombotic microangiopathy illustrates uncertainties regarding incidence, risk factors, diagnosis, treatment, and survival. These studies have suggested the lack of efficacy of plasma exchange treatment and have identified other transplant-related complications, such as acute graft-versus-host disease and opportunistic infections, as the predominant causes of death in patients who had been diagnosed with posttransplantation thrombotic microangiopathy. Recently consensus diagnostic criteria were proposed by two independent groups to provide more uniform identification of patients with posttransplantation thrombotic microangiopathy; these criteria may result in a clearer definition of this syndrome.

SUMMARY

Posttransplantation thrombotic microangiopathy remains a diagnostic and therapeutic challenge. Further studies are required to determine if it is a specific entity and to define its relation to other transplant-related complications.