Thrombotic thrombocytopenic purpura-like syndromes following bone marrow transplantation: an analysis of associated conditions and clinical outcomes

Endothelial Dysfunction Syndromes after Allogeneic Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only therapy with a curative potential for a variety of malignant and non-malignant diseases. The major limitation of the procedure is the significant morbidity and mortality mainly associated with the development of graft versus host disease (GVHD) as well as with a series of complications related to endothelial injury, such as sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD), transplant-associated thrombotic microangiopathy (TA-TMA), etc. Endothelial cells (ECs) are key players in the maintenance of vascular homeostasis and during allo-HSCT are confronted by multiple challenges, such as the toxicity from conditioning, the administration of calcineurin inhibitors, the immunosuppression associated infections, and the donor alloreactivity against host tissues. The early diagnosis of endothelial dysfunction syndromes is of paramount importance for the development of effective prophylactic and therapeutic strategies. There is an urgent need for the better understanding of the pathogenetic mechanisms as well as for the identification of novel biomarkers for the early diagnosis of endothelial damage. This review summarizes the current knowledge on the biology of the endothelial dysfunction syndromes after allo-HSCT, along with the respective therapeutic approaches, and discusses the strengths and weaknesses of possible biomarkers of endothelial damage and dysfunction.

Transplant-Associated Thrombotic Microangiopathy in the Context of Allogenic Hematopoietic Stem Cell Transplantation: Where We Stand

Transplant-associated thrombotic microangiopathy (TA-TMA) constitutes a significant contributor to the increased morbidity and mortality after allogenic hematopoietic stem cell transplantation (allo-HSCT). TA-TMA is a heterogenous disease, characterized by the triad of endothelial cell activation, complement dysregulation and microvascular hemolytic anemia, which may affect all organs. The lack of consensus diagnostic criteria, along with the common clinical features mimicking other diseases that complicate allo-HSCT, make the diagnosis of TA-TMA particularly challenging. Significant effort has been made to recognize specific risk factors predisposing to the development of TA-TMA and to identify serum biomarkers predicting the development of the disease. With regard to treatment, therapeutic plasma exchange (TPE) has been traditionally used, although with doubtful efficacy. On the other hand, the pivotal role of complement activation in the pathophysiology of TA-TMA has led to the exploration of the therapeutic potential of complement inhibitors in this setting. Eculizumab has been proposed as a first-line therapeutic agent in TA-TMA, owing to the very promising results in both pediatric and adult clinical trials. Pharmacokinetic and pharmacodynamic studies and CH50 levels are of paramount importance in the allo-HSCT setting, as a different dosing schedule (more intensive-in dose and frequency-at the beginning) seems to be required for successful outcomes. Furthermore, Narsoplimab, a MASP-2 inhibitor, recently received a Breakthrough Therapy Designation from the FDA for the treatment of TA-TMA after allo-HSCT. Finally, the decision to withdraw the CNIs, although initially advised by the Bone and Marrow Transplant Clinical Trials Network Committee, remains debatable owing to the controversial results of recent clinical trials. This review summarizes the current updates on pathophysiology, diagnosis and therapeutic approaches and emphasizes future goals and perspectives.

Comparison of clinical characteristics of first-episode thrombotic thrombocytopenic purpura and TTP-like syndrome: a retrospective cohort study in a level I hematology center in China

Comparing the characteristics of thrombotic thrombocytopenic purpura (TTP) and TTP-like syndrome patients at admission will allow early differentiation of TTP from TTP-like syndrome and help tailor initial treatment. The medical records of 78 patients with suspected TTP in the Emergency Department of Peking University People's Hospital in the past 5 years were retrospectively analyzed and divided into TTP and TTP-like syndrome groups based on ADAMTS13 activity and ADAMTS13 antibody titer. There were 25 and 53 patients in the TTP group and the TTP-like syndrome group, respectively. The neutrophil-to-lymphocyte ratio (P = 0.025) was tremendously higher, and albumin (P = 0.002) was lower in the TTP-like syndrome group, indicating a more severe inflammation. Compared with the TTP-like syndrome group, the TTP group had an approximately two-fold to three-fold higher prevalence of central nervous system dysfunction (P < 0.001). Also, hemolysis was more substantial in the TTP group as evidenced by higher schistocytes (P < 0.001), reticulocyte (P < 0.001), total bilirubin (P = 0.002), indirect bilirubin (P < 0.001), lactate dehydrogenase (P = 0.007) and cell-free hemoglobin (P < 0.001), simultaneously lower platelet (P < 0.001), haptoglobin (P = 0.044), and ADAMTS13 activity (P < 0.001). The Kaplan-Meier survival analysis showed that the TTP group significantly predicted poor prognosis (log-rank test: X² = 5.368, P = 0.021). TTP and TTP-like syndrome are two kinds of distinct phenotypes with different hemolysis statuses and illustrated differentiated inflammatory reactions, target organ damage (TOD), and the clinical outcome.

Thrombotic microangiopathy in oncology - a review

Thrombotic microangiopathy is a syndrome triggered by a wide spectrum of situations, some of which are specific to the Oncology setting. It is characterized by a Coombs-negative microangiopathic haemolytic anemia, thrombocytopenia and organ injury, with characteristic pathological features, resulting from platelet microvascular occlusion.

TMA is rare and its cancer-related subset even more so. TMA triggered by drugs is the most common within this group, including classic chemotherapy and the latest targeted therapies. The neoplastic disease itself and hematopoietic stem-cell transplantation could also be potential triggers.

Evidence-based medical guidance in the management of cancer-related TMA is scarce and the previous knowledge about primary TMA is valuable to understand the disease mechanisms and the potential treatments.

Given the wide spectrum of potential causes for TMA in cancer patients, the aim of this review is to gather the vast information available. For each entity, pathophysiology, clinical features, therapeutic approaches and prognosis will be covered.

Plasma exchange and thrombotic microangiopathies: From pathophysiology to clinical practice

Thrombotic microangiopathy (TMA) brings together many diseases that have a commonality in the apparition of mechanical hemolysis with consuming thrombopenia. In all cases, these diseases can be life threatening, thereby justifying the implementation of treatment as an emergency. First-line treatment represents plasma exchange. This treatment has proven efficiency in improving the vital patient's and functional prognosis. However, the administration methods of plasma exchange can be redefined in light of the understanding of the pathophysiology of TMA. The aim of this review is to try to define, from pathophysiology, the place of plasma exchanges in the modern therapeutic arsenal of TMA.

The ADVIA2120i parameter Revised %MICRO is a surrogate marker of schistocyte formation after hematopoietic stem cell transplantation

Objectives : Hematopoietic stem cell transplantation (HSCT)-associated thrombotic microangiopathy (TA-TMA) is an important early post-treatment condition. This study evaluated the Revised %MICRO, a parameter obtained from the ADVIA 2120i automated blood cell counter, as a surrogate marker of the schistocyte ratio. We hypothesized that individual differences between the %MICRO value and schistocyte ratio would remain constant. Design and Methods: EDTA-2K-treated peripheral blood samples were collected from 19 patients who underwent allogeneic HSCT from April 2014 to September 2018. First, the baseline difference, X, was calculated using a sample from the first day after HSCT as X = %MICRO (first day) - schistocyte ratio (first day). Next, the Revised %MICRO for each subsequent day was calculated as Revised %MICRO = %MICRO - X. We evaluated correlations of the schistocyte ratio with the calculated %MICRO and Revised %MICRO and the RBC fragment, RBC distribution width, %MICRO and Revised %MICRO data obtained from the ADVIA 2120i. Results : The mean schistocyte percentage and Revised %MICRO were both 0.4% ± 0.6. RBC fragments correlated weakly with the %MICRO and schistocyte ratio, respectively (r = 0.162 and r = 0.771, respectively), whereas the Revised %MICRO correlated strongly with the schistocyte ratio (r = 0.893). Conclusion : The Revised %MICRO appears to be a good surrogate of the schistocyte ratio in a clinical setting. J. Med. Invest. 67 : 250-254, August, 2020.

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.

Permanent Impairment-Free, Relapse-Free Survival: A Novel Composite Endpoint to Evaluate Long-Term Success in Allogeneic Transplantation

Permanent impairment (PI) of vital organs is one of the transplantation-related health problems affecting the quality of life and morbidity even in patients who do not develop graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (allo-HCT), but no data are available on PI of multiple organs. This retrospective study aimed to estimate a novel composite endpoint of PI-free, relapse-free survival (PIRFS) in 164 allo-HCT recipients. We defined PI as >26% to 30% impairment of the whole person in 6 vital organs using the whole person impairment rating. Conventional GVHD-free/relapse-free survival (GRFS) and PIRFS at 5 years were 33.8% (95% confidence interval [CI], 26.5% to 41.3%) and 40.6% (95% CI, 32.6% to 48.4%), respectively. In the whole cohort, PIRFS was higher than GRFS at any time after allo-HCT. However, PIRFS was lower than GRFS after day 397 post-transplantation in patients who underwent umbilical cord blood transplantation (UCBT). In UCBT recipients, 5-year GRFS and PIRFS were 47.6% (95% CI, 34.3% to 59.7%) and 39.2% (95% CI, 26.6% to 51.5%), respectively. The cumulative incidence of PI after 5 years was 20.9% (95% CI, 13.7% to 29.0%) in patients surviving for ≥6 months without relapse. The multivariate analysis revealed that high disease risk (hazard ratio [HR], 1.91; 95% CI, 1.26 to 2.88; P < .01) and Karnofsky Performance Status score ≤90% at transplantation (HR, 1.73; 95% CI, 1.14 to 2.63; P = .01) were correlated with the lower PIRFS, whereas UCBT (HR, 2.35; 95% CI, 1.11 to 4.99; P = .03), grade III-IV acute GVHD by day 180 (HR, 3.59; 95% CI, 1.04 to 12.4; P = .04), and thrombotic microangiopathy by day 180 (HR, 2.74; 95% CI, 1.10 to 6.87; P = .03) were significantly correlated with a higher incidence of PI. More than 20% of long-term survivors had PI. Our data suggest that PIRFS is a useful endpoint for assessing long-term transplantation success from a different perspective than has been established previously.

Late Presentation of Carfilzomib Associated Thrombotic Microangiopathy

Multiple Myeloma (MM) is a plasma cell disorder characterized by abnormal proliferation of plasma cells resulting in overproduction of paraprotein. Proteasome inhibitors (PI) have been a corner stone for the treatment of MM. Thrombotic Microangiopathy (TMA) is a recent hematological adverse event that has newly been recognized in multiple PI. TMA leads to end-organ damage and infarction by microthromobi. TMA pathophysiology is not well understood and has multiple etiologies. We present a case of PI-induced TMA, along with literature review of cases diagnosed from 2008-2018. Unique to our case is the onset of presentation, more than 24 months after initiating carfilzomib. Our case highlights the need for vigilant monitoring and the importance of clinical suspicion in patients at risk for TMA.

Delayed Development of Hemolytic Anemia with Fragmented Red Blood Cells and Cardiac and Renal Impairments after High-Dose Chemotherapy and Autologous Hematopoietic Stem Cell Transplantation for Malignant Lymphoma

Among 42 consecutive patients with malignant lymphoma who underwent high-dose chemotherapy (HDC) followed by autologous hematopoietic stem cell transplantation (AHSCT), 5 developed hemolytic anemia with fragmented red blood cells (HA-FrRBCs) on days 87-125 (median 107) of AHSCT. Nadir Hb levels ranged between 5.0 and 6.4 g/dL with 2.2-5.6% FrRBCs. All patients developed grade ≥3 hypoxia and heart failure, and 4 developed grade ≥3 hypertension. The ejection fraction of the left ventricle assessed by echocardiography was significantly reduced in 3 patients. Peak creatinine levels were >4 times above the baseline and estimated glomerular filtration rates were reduced to <30 mL/min/1.73 m2. One patient received plasma exchange, while the remaining 4 responded to treatment with diuretics and cardiovascular agents. Hematological parameters normalized within a median duration of 91 days after the development of HA-FrRBCs. Renal and cardiac functions gradually improved, even though renal function did not return to the baseline. HA-FrRBCs associated with cardiac and renal impairments may represent a thrombotic microangiopathy syndrome and are a delayed complication of HDC/AHSCT. The close monitoring of laboratory abnormalities and persistent treatment with cardiovascular agents and diuretics are the mainstay for the management of this condition.

Thrombotic Microangiopathy after Allogeneic Stem Cell Transplantation: A Comparison of Eculizumab Therapy and Conventional Therapy

We report the results of a single-center analysis of a cohort of 39 patients treated between 1997 and 2016 for transplantion-associated thrombotic microangiopathy. We evaluated 2 subgroups of patients: 24 patients treated between 1997 and 2014 who received conventional therapy and 15 patients treated with the complement-inhibiting monoclonal antibody eculizumab between 2014 and 2016. The conventional therapy group was treated predominantly with defibrotide alone or in combination with plasmapheresis or rituximab. Despite an initial response rate of 61%, only 4 patients (16%) were long-term survivors, 2 of whom had a low-risk thrombotic microangiopathy without multiorgan damage. Progression of thrombotic micorangiopathy and bacterial/fungal infections contributed equally to treatment failure. The overall response rate in the eculizumab group was significantly higher, at 93%. In addition, we were able to stop eculizumab treatment in 5 patients (33%), all of whom had high-risk thrombotic microangiopathy, due to sustained recovery. Despite the very good response in the eculizumab-treated group, we did not observe a significant improved overall survival, due primarily to a high rate of infection-related mortality (70%). Therefore, further studies are needed to identify the optimal therapeutic management approach for transplantation-associated thrombotic microangiopathy to improve its dismal outcome.

Pernicious Anemia Associated Cobalamin Deficiency and Thrombotic Microangiopathy: Case Report and Review of the Literature

A 43-year-old Hispanic male without significant previous medical history was brought to emergency department for syncope following a blood draw to investigate a 40 lbs weight loss during the past 6 months associated with decreased appetite and progressive fatigue. The patient also reported a 1-month history of jaundice. On examination, he was hemodynamically stable and afebrile with pallor and diffuse jaundice but without skin rash or palpable purpura. Normal sensations and power in all extremities were evident on neurological exam. Presence of hemolytic anemia, schistocytosis, thrombocytopenia, and elevated lactate dehydrogenase (LDH) was suggestive of thrombotic thrombocytopenic purpura (TTP). However, presence of leukopenia, macrocytes, and an inadequate reticulocyte response to the degree of anemia served as initial clues to an alternative diagnosis. Two and one units of packed red blood cells were transfused on day 1 and day 3, respectively. In addition, one unit of platelets was transfused on day 2. Daily therapeutic plasma exchange (TPE) was initiated and continued until ADAMTS-13 result ruled out TTP. A low cobalamin (vitamin B12) level was evident at initial laboratory work-up and subsequent testing revealed positive intrinsic factor-blocking antibodies supporting a diagnosis of pernicious anemia with severe cobalamin deficiency. Hematological improvement was observed following vitamin B12 supplementation. The patient was discharged and markedly improved on day 9 with outpatient follow-up for cobalamin supplementation.

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.

Thrombotic microangiopathy associated with proteasome inhibitors

The ubiquitin proteasome pathway plays a key role in cell cycle, function and survival. Bortezomib (BTZ) and Carfilzomib (CFZ) are the first two inhibitors of the proteasome pathway, indicated in treatment of patients with multiple myeloma. In the past few years, there have been few case reports that have highlighted the association between proteasome inhibitors (BTZ and CFZ) with acute kidney injury (AKI). In most of these case reports and initial trials, the underlying mechanism of AKI has been unclear. In this article, we discuss the association and pathogenesis of proteasome inhibitors-associated AKI. We also report the first case of CFZ-associated AKI with kidney biopsy evidence of thrombotic microangiopathy and the presence of microangiopathic hemolytic anemia.

Thrombotic microangiopathy, cancer, and cancer drugs

Thrombotic microangiopathy (TMA) is a complication that can develop directly from certain malignancies, but more often results from anticancer therapy. Currently, the incidence of cancer drug-induced TMA during the last few decades is >15%, primarily due to the introduction of anti-vascular endothelial growth factor (VEGF) agents. It is important for clinicians to understand the potential causes of cancer drug-induced TMA to facilitate successful diagnosis and treatment. In general, cancer drug-induced TMA can be classified into 2 types. Type I cancer drug-induced TMA includes chemotherapy regimens (ie, mitomycin C) that can potentially promote long-term kidney injury, as well as increased morbidity and mortality. Type II cancer drug-induced TMA includes anti-VEGF agents that are not typically associated with cumulative dose-dependent cell damage. In addition, functional recovery of kidney function often occurs after drug interruption, assuming a type I agent was not given prior to or during therapy. There are no randomized controlled trials to provide physician guidance in the management of TMA. However, previously accumulated information and research suggest that endothelial cell damage has an underlying immunologic basis. Based on this, the emerging trend includes the use of immunosuppressive agents if a refractory or relapsing clinical course that does not respond to plasmapheresis and steroids is observed.

Bone marrow transplantation improves autoinflammation and inflammatory bone loss in SH3BP2 knock-in cherubism mice

Cherubism (OMIM#118400) is a genetic disorder in children characterized by excessive jawbone destruction with proliferation of fibro-osseous lesions containing a large number of osteoclasts. Mutations in the SH3-domain binding protein 2 (SH3BP2) are responsible for cherubism. Analysis of the knock-in (KI) mouse model of cherubism showed that homozygous cherubism mice (Sh3bp2(KI/KI)) spontaneously develop systemic autoinflammation and inflammatory bone loss and that cherubism is a TNF-α-dependent hematopoietic disorder. In this study, we investigated whether bone marrow transplantation (BMT) is effective for the treatment of inflammation and bone loss in Sh3bp2(KI/KI) mice. Bone marrow (BM) cells from wild-type (Sh3bp2(+/+)) mice were transplanted to 6-week-old Sh3bp2(KI/KI) mice with developing inflammation and to 10-week-old Sh3bp2(KI/KI) mice with established inflammation. Six-week-old Sh3bp2(KI/KI) mice transplanted with Sh3bp2(+/+) BM cells exhibited improved body weight loss, facial swelling, and survival rate. Inflammatory lesions in the liver and lung as well as bone loss in calvaria and mandibula were ameliorated at 10weeks after BMT compared to Sh3bp2(KI/KI) mice transplanted with Sh3bp2(KI/KI) BM cells. Elevation of serum TNF-α levels was not detected after BMT. BMT was effective for up to 20weeks in 6-week-old Sh3bp2(KI/KI) mice transplanted with Sh3bp2(+/+) BM cells. BMT also ameliorated the inflammation and bone loss in 10-week-old Sh3bp2(KI/KI) mice. Thus our study demonstrates that BMT improves the inflammation and bone loss in cherubism mice. BMT may be effective for the treatment of cherubism patients.

Renal thrombotic microangiopathy and podocytopathy associated with the use of carfilzomib in a patient with multiple myeloma

BACKGROUND

Proteasome inhibitors are a relatively new class of chemotherapeutic agents. Bortezomib is the first agent of this class and is currently being used for the treatment of multiple myeloma. However, recent reports have linked exposure to bortezomib with the development of thrombotic microangiopathy. A new agent in this class, carfilzomib, has been recently introduced as alternative therapy for relapsing and refractory multiple myeloma. We report a case of renal thrombotic microangiopathy associated with the use of carfilzomib in a patient with refractory multiple myeloma.

CASE PRESENTATION

A 62 year-old Caucasian man with hypertension and a 4-year history of multiple myeloma, had been previously treated with lenalidomide, bortezomib and two autologous hematopoietic stem cell transplants. After the second hematopoietic stem cell transplant, he developed acute kidney injury secondary to septic shock and required dialysis for 4 weeks. Subsequently, his serum creatinine stabilized at 2.1 mg/dL (185.64 μmol/L). Seventeen months after the second hematopoietic stem cell transplant, he was initiated on carfilzomib for relapse of multiple myeloma. Six weeks later, he developed abrupt worsening of lower extremity edema and hypertension, and new onset proteinuria. His kidney function remained stable. Kidney biopsy findings were consistent with thrombotic microangiopathy. Eight weeks after discontinuation of carfilzomib, proteinuria and hypertension improved. Due to progression of multiple myeloma, he died a few months later.

CONCLUSION

In view of the previously reported association of bortezomib with thrombotic microangiopathy, the temporal association of the clinical picture with the initiation of carfilzomib, and the partial resolution of symptoms after discontinuation of the drug, we conclude that carfilzomib may have precipitated a case of clinically evident renal thrombotic microangiopathy in our patient.

Kidney complications of hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) exposes a patient's kidneys to a unique combination of challenges, including high-dose radiation, anemia, chemotherapeutic agents, graft-versus-host disease, opportunistic infections, attenuated and altered immunologic responses, fluid and electrolyte imbalances, and extensive courses of antimicrobial agents. Since the inception of HSCT in the 1950s, there has been increasing interest in defining, determining, and managing the kidney complications that accompany this procedure. In this article, we review the common causes of acute kidney injury and chronic kidney disease that occur with HSCT, including HSCT-associated thrombotic microangiopathy, a distinct cause of chronic kidney disease with a multifactorial cause previously known as bone marrow transplant nephropathy or radiation nephropathy. Additionally, we review other kidney complications, including calcineurin inhibitor nephrotoxicity and chronic graft-versus-host disease-associated glomerulonephritis, that develop post-HSCT. Critically, due to its grave prognosis, it is important to identify HSCT-associated thrombotic microangiopathy early, as well as distinguish it from the other causes of chronic kidney disease.

Systemic infections mimicking thrombotic thrombocytopenic purpura

The absence of specific diagnostic criteria, the urgency to begin plasma exchange treatment, and the risk for complications from plasma exchange make the initial evaluation of patients with suspected thrombotic thrombocytopenic purpura (TTP) difficult. Systemic infections may mimic the presenting clinical features of TTP. In the Oklahoma TTP-HUS (hemolytic-uremic syndrome) Registry, 1989-2010, 415 consecutive patients have been clinically diagnosed with their first episode of TTP; in 31 (7%) the presenting clinical features were subsequently attributed to a systemic infection. All 31 patients had diagnostic criteria for TTP; 16 (52%) had the complete "pentad" of microangiopathic hemolytic anemia, thrombocytopenia, neurologic abnormalities, renal failure, and fever. Four (16%) of 25 patients who had ADAMTS13 measurements had <10% activity; three patients had a demonstrable ADAMTS13 inhibitor. Compared with 62 patients with severe ADAMTS13 deficiency (<10%) who had no recognized alternative disorders, patients with systemic infections had more frequent fever, coma, renal failure, and the complete "pentad" of clinical features. Seventeen different infectious etiologies were documented. A systematic literature review identified 67 additional patients with a diagnosis of TTP or HUS and also a systemic infection. Among all 98 patients, infections with 41 different bacteria, viruses, and fungi were documented, suggesting that many different systemic infections may mimic the presenting clinical features of TTP. Initial plasma exchange treatment is appropriate in critically ill patients with diagnostic features of TTP, even if a systemic infection is suspected. Continuing evaluation to document a systemic infection is essential to determine the appropriateness of continued plasma exchange.

Acute kidney injury in hematopoietic cell transplantation

Hematopoietic cell transplantation is becoming an increasingly common treatment modality for a variety of diseases. However, patient survival may be limited by substantial treatment-related toxicities, including acute kidney injury (AKI). AKI can develop in approximately 70% of patients posttransplant and is associated with an increased risk of morbidity and mortality. The development of AKI varies depending on the type of conditioning regimen used and the donor cells infused at the time of transplant, and the etiology often is multifactorial. Epidemiology, risk factors for development, pathogenesis, and potential treatment options for AKI in the hematopoietic cell transplantation population are reviewed as well as newer data on early markers of renal injury. As the indications for and number of transplants performed each year increases, nephrologists and oncologists will have to work together to identify patients who are at risk for AKI to both prevent its development and initiate therapy early to improve outcomes.

Transplantation-associated thrombotic microangiopathy after steroid pulse therapy for polyserositis related to graft-versus-host disease

Transplantation-associated thrombotic microangiopathy (TA-TMA) is a rare 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, graft-versus-host disease (GVHD) and opportunistic infections. TA-TMA has an unfavorable prognosis and responds poorly to conventional treatment including plasma exchange (PE). We present a case of a 37-year-old man with membranous nephropathy (MN) and polyserositis caused by GVHD after hematopoietic stem cell transplantation. He developed TA-TMA after steroid pulse therapy for polyserositis. We treated the patient with PE and mycophenolate mofetil (MMF) after which the TA-TMA successfully improved and the MN underwent complete remission. The present case suggests that corticosteroids with severe GVHD might increase the risk of TA-TMA, and that PE in combination with MMF may be a valuable therapy to improve the prognosis.

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.

How I treat patients with thrombotic thrombocytopenic purpura: 2010

Thrombotic thrombocytopenic purpura (TTP) is the common name for adults with microangiopathic hemolytic anemia, thrombocytopenia, with or without neurologic or renal abnormalities, and without another etiology; children without renal failure are also described as TTP. The diagnosis of TTP is an indication for plasma exchange treatment, but beginning treatment requires sufficient confidence in the diagnosis to justify the risk of plasma exchange complications. Documentation of a severe deficiency of plasma ADAMTS13 activity, defined as less than 10% of normal, is not essential for the diagnosis of TTP. Some patients without severe ADAMTS13 deficiency may benefit from plasma exchange treatment; in addition, some patients with severe ADAMTS13 deficiency may subsequently be diagnosed with another cause for their clinical features. However, severe acquired ADAMTS13 deficiency does define a subgroup of patients who appear to benefit from treatment with corticosteroids and other immunosuppressive agents in addition to plasma exchange but who have a high risk for relapse. Approximately 80% of patients survive their acute episode, a survival rate that has not changed since the introduction of plasma exchange treatment. Although recovery may appear to be complete, many patients have persistent minor cognitive abnormalities. More effective as well as safer treatment for TTP is needed.

Undifferentiated spondyloarthritis following allogeneic stem cell transplantation

BACKGROUND

Stem cell transplant has been utilized in the treatment of malignancies and rheumatic disease. Rheumatic disease may be transferred from the donor with active disease or may be developed in a recipient de novo as a late complication of SCT.

CASE PRESENTATION

We here report the rare case of a 26-year old male patient, who has been diagnosed with undifferentiated spondyloarthropathy after unique circumstance. The patient suffered from intermittent inflammatory back pain and peripheral joint swelling for several years and did not find relief through multiple emergency room visits at different medical facilities. After a thorough history and physical exam, it was noted that our patient had developed signs of axial disease along with dactylitis and overall that he had been insidiously developing an undifferentiated spondyloarthopathy after allogeneic stem cell transplantation.

CONCLUSION

Our observation supports the hypothesis that de novo rheumatic disease can develop after stem cell transplant for a variety of reasons. Thus, larger studies and awareness of this association are needed to delineate the exact underlying mechanism(s).

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.

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.

Evidence based therapeutic apheresis in autoimmune and other hemolytic anemias

PURPOSE OF REVIEW

This article reviews recent publications that bear on the evidential basis for therapeutic apheresis in diseases in which hemolytic anemia is a prominent feature.

RECENT FINDINGS

Therapeutic plasma exchange continues to be reported sporadically in severe autoimmune hemolytic anemia, with inconsistent results. Autoimmune deficiency of ADAMTS13 has provided a compelling rationale for therapeutic plasma exchange in some patients with thrombotic thrombocytopenic purpura; conversely such deficiency is consistently absent in certain clinically similar syndromes for which therapeutic plasma exchange is not or may not be beneficial. Refinements in assays for ADAMTS13 should further clarify its role in idiopathic thrombotic thrombocytopenic purpura. Oral iron chelators have shown promise in recent trials in chronically transfused patients with sickle cell disease and may provide an alternative to red cell exchange to prevent iron overload.

SUMMARY

The proper role of therapeutic plasma exchange in the treatment of autoimmune hemolytic anemia remains uncertain. Therapeutic plasma exchange continues to be indicated for idiopathic thrombotic thrombocytopenic purpura regardless of ADAMTS13 levels, but more accessible and physiological ADAMTS13 assays may raise questions about the rationale for and value of plasma exchange in ADAMTS13 nondeficient patients. Oral iron chelation may obviate the need for red cell exchange as a means to prevent iron overload in chronically transfused patients with sickle cell disease.

Toxic epidermal necrolysis and hemolytic uremic syndrome after allogeneic stem-cell transplantation

TEN and HUS are challenging complications with excessive mortality after HSCT. We report the development of these two conditions in combination in a nine-yr-old boy after HSCT from an unrelated donor. TEN with skin detachment of more than 90% of body surface area developed after initial treatment for GvHD. Within a few days of admission to the burns unit, the patient developed severe hemolysis, hypertension, thrombocytopenia, and acute renal failure consistent with HUS, apparently caused by CSA. The management included intensive care in a burns unit, accelerated drug removal using plasmapheresis, and a dedicated multi-disciplinary team approach to balance immunosuppression and infections management in a situation with extensive skin detachment. The patient survived and recovered renal function but requires continued treatment for severe GvHD. Suspecting and identifying causative drugs together with meticulous supportive care in the burns unit is essential in the management of these patients and long-term survival is possible.

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.

Stem cell transplantation nephropathy: a report of six cases

Stem cell transplantation (SCT) nephropathy is 1 cause of chronic kidney disease in patients after allogeneic SCT. It is a thrombotic microangiopathic syndrome characterized by raised creatinine, hypertension, and anemia. The difference with thrombotic thrombocytopenic purpura (TTP)-like syndromes is that it occurs later than 3 months after SCT, has marked renal dysfunction, and occurs in the absence of other complications or nephrotoxic medication. Total-body irradiation (TBI) in combination with previous chemotherapy is most likely the cause. We describe 6 cases of SCT nephropathy that occurred in a cohort of 363 patients who received myeloablative allogeneic SCT. All patients had TBI with shielding of the kidneys. We discuss the course of the syndrome, treatment, and outcome of the patients.

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.

Transplant-associated microangiopathy in patients receiving tacrolimus following allogeneic stem cell transplantation: risk factors and response to treatment

Transplant-associated microangiopathy (TAM) is a life-threatening complication after allogeneic HSCT, particularly with the use of calcineurin inhibitors as post-transplantation immunosuppressive therapy. We report our experience with TAM after HSCT with tacrolimus-based GVHD prophylaxis in a single-center study. Sixty-six of 1219 transplant recipients developed TAM with a cumulative incidence of 5.9%. Risk factors for TAM were female gender, lymphoid malignancy, receipt of a matched unrelated donor, and grade II-IV aGVHD. Most patients had infection and/or active GVHD at the diagnosis of TAM (82%). In the absence of renal dysfunction or encephalopathy, tacrolimus was generally continued, maintaining blood levels within the lower therapeutic range. Sixty-three patients were treated with plasma exchange. The cumulative incidence of response of TAM was 60%. Only 1 patient had a response of TAM without resolution of concomitant infections or GVHD. Six-month survivals were 0% and 50% for TAM nonresponders and responders, respectively. In conclusion, TAM is a common, life-threatening complication of allogeneic hematopoietic transplantation using tacrolimus prophylaxis. Control of TAM generally requires response of associated infections and GVHD. TMA response may occur despite continuation of tacrolimus treatment.