100 Years of Thrombotic Thrombocytopenic Purpura: A Story of Death and Life.

One hundred years ago, in 1924, the first description of a patient with a disease, now known as thrombotic thrombocytopenic purpura (TTP) was published by Dr. Eli Moschcowitz. In honor of this report, this article, written by distinguished specialists in TTP, reviews the increase in scientific knowledge on this disease during the last 100 years. It covers the scientific progress from plasma therapy, the first beneficial treatment for TTP, to the elucidation of the pathophysiology, the discovery of ADAMTS13, the development of assays and targeted therapies up to the modern treatment concepts, that improved the outcome of TTP from an incurable disease to a well understood and treatable disorder.

Emicizumab prophylaxis in patients with acquired haemophilia A (GTH-AHA-EMI): an open-label, single-arm, multicentre, phase 2 study.

BACKGROUND: Acquired haemophilia A is caused by neutralising autoantibodies against coagulation factor VIII, leading to severe bleeding. Standard treatment involves immunosuppressive therapy, which is associated with adverse events and mortality in the frail population of patients with acquired haemophilia A. This study investigated whether emicizumab, a factor VIIIa mimetic antibody, protects patients with acquired haemophilia A from bleeding and allows deferral of immunosuppression during the first 12 weeks after diagnosis. METHODS: We report final results of an open-label, single-arm, phase 2 clinical trial. Adult patients with acquired haemophilia A from 16 haemophilia treatment centres in Germany and Austria were eligible if they had not previously received immunosuppression. Patients received emicizumab subcutaneously (6 and 3 mg/kg on days 1 and 2, 1·5 mg/kg weekly until week 12), but no immunosuppression. Follow-up was until week 24. The primary endpoint was the number of clinically relevant bleeds per patient-week until week 12. Emicizumab was considered effective if the mean bleeding rate was significantly below 0·15 bleeds per patient-week, the rate observed in a previous study of patients with acquired haemophilia A treated with bypassing agents and immunosuppression but no emicizumab. The study is registered with clinicaltrials.gov, NCT04188639 and is complete. FINDINGS: Of 49 patients screened from March 25, 2021, to June 10, 2022, 47 were enrolled (23 women, 24 men). Median age was 76 years (IQR 66-80), 46 (98%) of 47 patients were White, median factor VIII activity was 1·4 IU/dL (0·3-5·6), and median inhibitor concentration was 11·4 Bethesda units per mL (3·9-42·7). Mean breakthrough bleeding rate was 0·04 bleeds per patient-week (upper 97·5% CI 0·06). 33 (70%) of 47 patients had no bleeding events, seven patients (15%) had one bleed, six patients (13%) had two bleeds, and one patient (2%) had three bleeds. Adverse events of grade 3 or worse included COVID-19 (n=2), acute kidney injury (n=2), and stroke (n=1). Four of 47 patients died, including two deaths related to bleeding, one from COVID-19, and one from cardiac arrest (none were judged as related to emicizumab). INTERPRETATION: This study suggests that emicizumab prophylaxis prevents bleeding in patients with acquired haemophilia A and that immunosuppressive therapy can be deferred while patients are receiving this treatment. The low number of thromboembolic events, severe infections, and fatalities observed in this study are promising. FUNDING: This study was supported by funding from Hoffman-La Roche.

Targets of autoantibodies in acquired hemophilia A are not restricted to factor VIII: data from the GTH-AH 01/2010 study.

The root cause of autoantibody formation against factor VIII (FVIII) in acquired hemophilia A (AHA) remains unclear. We aimed to assess whether AHA is exclusively associated with autoantibodies toward FVIII or whether patients also produce increased levels of autoantibodies against other targets. A case-control study was performed enrolling patients with AHA and age-matched controls. Human epithelial cell (HEp-2) immunofluorescence was applied to screen for antinuclear (ANA) and anticytoplasmic autoantibodies. Screening for autoantibodies against extractable nuclear antigens was performed by enzyme immunoassay detecting SS-A/Ro, SS-B/La, U1RNP, Scl-70, Jo-1, centromere B, Sm, double-stranded DNA, and α-fodrin (AF). Patients with AHA were more often positive for ANA than control patients (64% vs 30%; odds ratio [OR] 4.02, 1.98-8.18) and had higher ANA titers detected than controls. Cytoplasmic autoantibodies and anti-AF immunoglobulin A autoantibodies were also more frequent in patients with AHA compared with controls. Autoantibodies against any target other than FVIII were found in 78% of patients with AHA compared with 46% of controls (OR 4.16, 1.98-8.39). Results were similar preforming sensitivity analyses (excluding either subjects with autoimmune disorders, cancer, pregnancy, or immunosuppressive medication at baseline) and in multivariable binary logistic regression. To exclude that autoantibody staining was merely a result of cross-reactivity of anti-FVIII autoantibodies, we tested a mix of 7 well-characterized monoclonal anti-FVIII antibodies. These antibodies did not stain HEp-2 cells used for ANA detection. In conclusion, a diverse pattern of autoantibodies is associated with AHA, suggesting that a more general breakdown of immune tolerance might be involved in its pathology.

Management of acquired haemophilia A in severe Covid-19: Haemostatic bridging with emicizumab to keep the balance between bleeding and thrombosis.

Acquired haemophilia A (AHA) is an autoimmune bleeding disorder caused by autoantibodies blocking coagulation factor VIII (FVIII). Haemostatic management of AHA and concomitant thrombotic risk is difficult. We cover the management of a 75-year-old male with severe Covid-19, a prothrombotic disease, and de novo AHA with severe muscle bleeding, a disease requiring highly thrombogenic haemostatic therapy and immunosuppression-a challenging combination. FVIII activity was measured using human and bovine reagents to differentiate between endo- and exogenous FVIII activity. For haemostatic control, recombinant human activated FVII was given, followed by emicizumab, as a less thrombogenic long-term haemostatic agent. Steroids were used as initial immunosuppressive therapy. Later, rituximab was used for inhibitor eradication. No thromboembolic events occurred, and bleeding was effectively controlled. Emicizumab achieved haemostatic balance in a patient under haemorrhagic and thrombogenic conditions. Individual risk assessment is needed to guide treatment decisions in patients threatened by simultaneous bleeding and thrombosis.

Hereditary thrombotic thrombocytopenic purpura and COVID-19: Impacts of vaccination and infection in this rare disease.

Introduction: Severe COVID-19 is associated with an important increase of von Willebrand factor and mild lowering of ADAMTS13 activity that may, in the presence of a strong inflammatory reaction, increase the risk of acute thrombotic thrombocytopenic purpura (TTP). Although acute episodes of immune-mediated TTP associated with COVID-19 or SARS-CoV-2 vaccination have been reported, data about clinical evolution of hereditary TTP (hTTP) during the pandemic are scarce. Method: We conducted a survey among adult patients of the International Hereditary TTP Registry about SARS-CoV-2 vaccination, COVID-19, and occurrence of acute hTTP episodes. Results: Of 122 adult hTTP patients invited to participate, 86 (70.5%) responded. Sixty-five had been vaccinated (75.6%), of which 14 had received in addition a booster, resulting in 139 individual vaccine shots. Although vaccinations in patients on plasma prophylaxis were done within 1 week of the last plasma infusion, all 23 patients treated with plasma on demand were vaccinated without prior plasma infusions. One patient on uninterrupted weekly plasma infusions presented within 3 days from his second vaccination with neurological symptoms and computed tomography scan 9 days later showed subacute ischemic/hemorrhagic frontal lobe infarction. A second male patient developed acute myocarditis after his second dose of mRNA-1273 vaccine. Twelve (14%) patients had COVID-19, associated with an acute hTTP episode in three of them: one patient had a transient ischemic attack, one a stroke, and a pregnant woman was hospitalized to intensify plasma treatment. Discussion: The risk of an acute episode triggered by COVID-19 seems higher than following vaccination in hTTP patients, who can be safely vaccinated against SARS-CoV-2.

Long-term follow-up of patients treated with caplacizumab and safety and efficacy of repeat caplacizumab use: Post-HERCULES study.

INTRODUCTION: Caplacizumab demonstrated efficacy and safety in patients with immune-mediated thrombotic thrombocytopenic purpura (iTTP) in the phase 3 HERCULES trial. However, data on long-term outcomes following caplacizumab treatment are limited. OBJECTIVES: The post-HERCULES trial (NCT02878603) evaluated long-term outcomes of patients with iTTP treated with caplacizumab in HERCULES and safety and efficacy of repeated caplacizumab use. PATIENTS/METHODS: Over 3 years of follow-up, patients could receive open-label caplacizumab with therapeutic plasma exchange (TPE) and immunosuppressive therapy (IST) in case of recurrence. Adverse events (AEs) were assessed during the overall study period (intention-to-observe [ITO] population) and during recurrences (recurrence population). TTP-related events (TTP-related death, recurrence, major thromboembolic events) were assessed in the efficacy ITO population (patients without recurrence during HERCULES or before post-HERCULES). RESULTS: Among 104 enrolled patients, incidences of AEs and serious AEs were similar between patients who had received caplacizumab + TPE + IST during HERCULES (n = 75) and those treated with placebo + TPE + IST (placebo; n = 29). TTP-related events occurred in 8% of patients (4/49) randomized to caplacizumab during HERCULES versus 38% (11/29) randomized to placebo. Nineteen patients had ≥1 recurrence; 13 of these were treated with caplacizumab. The first recurrence episode was resolved or resolving for all patients treated with caplacizumab, including nine patients with repeat caplacizumab use. All second recurrences (6/6) were resolved. Safety profile of caplacizumab for treatment of recurrence was consistent with HERCULES; most bleeding events were nonserious. No major cases of organ dysfunction were observed. CONCLUSIONS: Long-term follow-up supports the safety and efficacy of caplacizumab for iTTP and its repeated use for recurrences.

Subcutaneous Enoxaparin for Systemic Anticoagulation of COVID-19 Patients During Extracorporeal Life Support.

Background: Extracorporeal membrane oxygenation, with an inherent requirement for anticoagulation to avoid circuit thrombosis, is a key element in the treatment of respiratory failure associated with COVID-19. Anticoagulation remains challenging, the standard of care being intravenous continuous administration of unfractionated heparin. Yet regimens vary. Some intensive care units in our center have successfully used enoxaparin subcutaneously in recent years and throughout the pandemic. Methods: We retrospectively analyzed adult COVID-19 patients with respiratory failure who had been systemically anticoagulated using either enoxaparin or unfractionated heparin. The choice of anticoagulant therapy was based on the standard of the intensive care unit. Defined thromboembolic and hemorrhagic events were analyzed as study endpoints. Results: Of 98 patients, 62 had received enoxaparin and 36 unfractionated heparin. All hazard ratios for the thromboembolic (3.43; 95% CI: 1.08-10.87; p = 0.04), hemorrhagic (2.58; 95% CI: 1.03-6.48; p = 0.04), and composite (2.86; 95% CI: 1.41-5.92; p = 0.007) endpoints favored enoxaparin, whose efficient administration was verified by peak levels of anti-factor Xa (median: 0.45 IU ml-1; IQR: 0.38; 0.56). Activated partial thromboplastin time as well as thrombin time differed significantly (both p<0.001) between groups mirroring the effect of unfractionated heparin. Conclusions: This study demonstrates the successful use of subcutaneous enoxaparin for systemic anticoagulation in patients with COVID-19 during extracorporeal membrane oxygenation. Our findings are to be confirmed by future prospective, randomized, controlled trials.

Alternate-day dosing of caplacizumab for immune-mediated thrombotic thrombocytopenic purpura.

BACKGROUND: The anti-von Willebrand factor (VWF) nanobody caplacizumab directly prevents the fatal microthrombi formation in immune-mediated thrombotic thrombocytopenic purpura (iTTP), thereby adding a new therapeutic principle to the treatment of this disorder. However, real-world treatment modalities beyond clinical trials remain heterogeneous. METHODS: Here, we describe the risks and benefits of an alternate-day dosing regimen for caplacizumab by thoroughly analyzing the timing and outcome of this approach in a retrospective cohort of 25 iTTP patients treated with caplacizumab at seven different medical centers in Austria and Germany between 2018 and 2021. RESULTS: Alternate-day dosing of caplacizumab appeared feasible and led to persisting normal platelet counts in most patients. Five patients experienced iTTP exacerbations or relapses that led to the resumption of daily caplacizumab application. VWF activity was repeatedly measured in 16 of 25 patients and documented sufficient suppression by caplacizumab after 24 and 48 h in line with published pharmacodynamics. CONCLUSION: Extension of caplacizumab application intervals from daily to alternate-day dosing may be safely considered in selected patients after 3 to 4 weeks of daily treatment. Earlier modifications may be discussed in low-risk patients but require close monitoring for clinical and laboratory features of thrombotic microangiopathy.

Secondary basophilic leukemia in Ph-negative myeloid neoplasms: A distinct subset with poor prognosis.

During progression of myeloid neoplasms, the basophil compartment may expand substantially and in some of these patients, a basophilic leukemia is diagnosed. In patients with Ph-chromosome+ chronic myeloid leukemia, acceleration of disease is typically accompanied by marked basophilia. In other myeloid neoplasms, secondary leukemic expansion of basophils is rarely seen. We report on 5 patients who suffered from a myelodysplastic syndrome, myeloproliferative neoplasm, or acute leukemia and developed a massive expansion of basophils during disease progression. In 4 of 5 patients, peripheral blood basophil counts reached 40%, and the diagnosis "secondary basophilic leukemia" was established. As assessed by flow cytometry, neoplastic basophils expressed CD9, CD18, CD25, CD33, CD63, PD-L1, CD123, and CLL-1. In addition, basophils were found to display BB1 (basogranulin), 2D7, tryptase and KIT. In 4 of 5 patients the disease progressed quickly and treatment with azacitidine was started. However, azacitidine did not induce major clinical responses, and all patients died from progressive disease within 3 Y. In in vitro experiments, the patients´ cells and the basophilic leukemia cell line KU812 showed variable responses to targeted drugs, including azacitidine, venetoclax, hydroxyurea, and cytarabine. A combination of venetoclax and azacitidine induced cooperative antineoplastic effects in these cells. Together, secondary basophilic leukemia has a poor prognosis and monotherapy with azacitidine is not sufficient to keep the disease under control for longer time-periods. Whether drug combination, such as venetoclax+azacitidine, can induce better outcomes in these patients remains to be determined in future clinical studies.

Prevalence and Clinical Impact of Reduced Coagulation Factor XII Activity in Patients Receiving Extracorporeal Membrane Oxygenation.

OBJECTIVES: Extracorporeal membrane oxygenation provides large surface exposure to human blood leading to coagulation activation. Only limited clinical data are available on contact activation and coagulation factor XII activity in extracorporeal membrane oxygenation patients. DESIGN: Prospective cohort study. SETTING: Three medical ICUs at the Medical University of Vienna. PATIENTS: Adult patients receiving venovenous or venoarterial extracorporeal membrane oxygenation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The primary outcome was the change in coagulation factor XII activity in response to extracorporeal membrane oxygenation. Secondary outcomes included the prevalence of reduced coagulation factor XII activity (< 60%) among patients receiving extracorporeal membrane oxygenation and association of coagulation factor XII activity with thromboembolic and bleeding complications. An exploratory endpoint was the association of coagulation factor XII activity and activated partial thromboplastin time in heparinase-treated samples in vitro. Fifty-one patients with a total of 117 samples were included in the study between July 2018 and February 2020. Fifty patients (98%) had reduced coagulation factor XII activity at any timepoint during extracorporeal membrane oxygenation. Median coagulation factor XII activity during extracorporeal membrane oxygenation treatment was 30% (interquartile range, 21.5-41%) and increased after discontinuation (p = 0.047). Patients with thromboembolic complications had higher median coagulation factor XII activity during extracorporeal membrane oxygenation (34% vs 23%; p = 0.023). The odds of a thromboembolic event increased by 200% per tertile of median coagulation factor XII activity (crude odds ratio, 3.034; 95% CI, 1.21-7.63). No association with bleeding was observed. In heparinase-treated samples, coagulation factor XII activity correlated well with activated partial thromboplastin time (r = -0.789; p = 0.007). CONCLUSIONS: We observed a high prevalence of reduced coagulation factor XII activity in adult patients on extracorporeal membrane oxygenation, which may confound activated partial thromboplastin time measurements and limit its clinical usefulness for monitoring and titrating anticoagulation with unfractionated heparin. Lower coagulation factor XII activity was associated with less thromboembolic complications, which may highlight the potential of coagulation factor XII to serve as a target for anticoagulation in extracorporeal membrane oxygenation.

Successful treatment of vaccine-induced prothrombotic immune thrombocytopenia (VIPIT).

Cases of unusual thrombosis and thrombocytopenia after administration of the ChAdOx1 nCoV-19 vaccine (AstraZeneca) have been reported. The term vaccine-induced prothrombotic immune thrombocytopenia (VIPIT) was coined to reflect this new phenomenon. In vitro experiments with VIPIT patient sera indicated that high-dose intravenous immunoglobulins (IVIG) competitively inhibit the platelet-activating properties of ChAdOx1 nCoV-19 vaccine induced antibodies. Here, we report a case of a 62-year-old woman who had received this vaccine and developed VIPIT. She visited the emergency ward because of petechiae and hematomas. In the laboratory work-up, thrombocytopenia, low fibrinogen, elevated D-dimer, and positivity in the platelet factor 4/heparin-enzyme-immunoassay were present. Signs and symptoms of thrombosis were absent. Upon immediate therapy with non-heparin anticoagulation, high-dose IVIG, and prednisolone, laboratory parameters steadily improved and the patient was discharged from hospital without thrombotic complications. We conclude that early initiation of VIPIT treatment results in a swift response without thrombotic complications.

Risk of Clinically Relevant Venous Thromboembolism in Critically Ill Patients With COVID-19: A Systematic Review and Meta-Analysis.

Background: Early during the course of the ongoing COVID-19 pandemic, reports suggested alarmingly high incidences for thromboembolic events in critically ill patients with COVID-19. However, the clinical relevance of these events was not reported in several studies. Additionally, more recent research showed contradictory results and suggested substantially lower rates of venous thromboembolism. Thus, the aim of the present study was to summarize evidence on the incidence of clinically relevant venous thromboembolism (VTE)-defined as VTE excluding isolated subsegmental pulmonary embolism (PE) and distal deep vein thrombosis (DVT)-in adult critically ill patients with COVID-19. Methods: We performed a systematic review of studies reporting the incidence of clinically relevant PE and/or DVT in critically ill patients with COVID-19. Scientific reports published in the English language between January and October 2020 were included. We conducted a random-effects model meta-analysis to calculate incidence estimates of clinically relevant VTE and bleeding events. We also performed exploratory meta-regression and subgroup analyses of different diagnostic approaches and additional factors that possibly influenced the incidence of these outcomes. Results: Fifty-four articles (5,400 patients) fulfilled the predefined inclusion criteria, of which 41 had a high risk of bias. The majority of included patients were male, > 60 years, and overweight. Twenty-one studies reported the use of prophylactic doses of heparin. Pooled incidences for clinically relevant PE were estimated at 8% (95% CI, 4-11%), for proximal DVT at 14% (95% CI, 9-20%), and-after exclusion of studies with a high risk of bias-for the composite outcome of VTE at 18% (95% CI, 13-24%). Clinically relevant bleeding occurred at a rate of 6% (95% CI, 2-9%). Conclusions: We summarized currently available data on the rate of clinically relevant VTE in critically ill patients with COVID-19. Pooled incidence estimates were lower than those reported by previous review articles. In the absence of evidence-based anticoagulation guidelines for critically ill patients with COVID-19, the results of our study provide clinically important information for an individual risk-benefit assessment in this context. Registration: The study protocol was prospectively registered in PROSPERO on June 22, 2020 (CRD42020193353; https://www.crd.york.ac.uk/prospero).

Annual incidence and severity of acute episodes in hereditary thrombotic thrombocytopenic purpura.

Hereditary thrombotic thrombocytopenic purpura (hTTP) is a rare thrombotic microangiopathy characterized by severe congenital ADAMTS13 deficiency and recurring acute episodes causing morbidity and premature death. Information on the annual incidence and severity of acute episodes in patients with hTTP is largely lacking. This study reports prospective data on 87 patients from the Hereditary TTP Registry (clinicaltrials.gov #NCT01257269) for survival, frequency, and severity of acute episodes from enrollment until December 2019. The 87 patients, followed up for a median of 4.2 years (range, 0.01-15 years), had a median age at overt disease onset and at clinical diagnosis of 4.6 years and 18 years (range, 0.0-70 years for both), respectively. Forty-three patients received regular plasma prophylaxis, whereas 22 did not, and treatment changed over time or was unknown in the remaining 22. Forty-three patients experienced 131 acute episodes, of which 91 (69%) occurred in patients receiving regular prophylaxis. This resulted in an annual incidence of acute episodes of 0.36 (95% confidence interval [CI], 0.29-0.44) with regular plasma treatment and of 0.41 (95% CI, 0.30-0.56) without regular plasma treatment. More than one-third of acute episodes (n = 51) were documented in children <10 years of age at enrollment and were often triggered by infections. Their annual incidence of acute episodes was significantly higher than in patients aged >40 years (1.18 [95% CI, 0.88-1.55] vs 0.14 [95% CI, 0.08-0.23]). The prophylactic plasma infusion regimens used were insufficient to prevent acute episodes in many patients. Such regimens are burdensome, and caregivers, patients, and their guardians are reluctant to start regular plasma infusions, from which children particularly would benefit.

Should emicizumab be used in patients with acquired hemophilia A?

Emicizumab is currently approved to prevent bleeding in patients with congenital hemophilia A with or without neutralizing antibodies (inhibitors) against factor VIII (FVIII). Here, we present a case-based discussion of its potential use in acquired hemophilia A (AHA), a severe bleeding disorder caused by autoantibodies against FVIII. State-of-the-art management is based on bypassing agents (recombinant factor VIIa, activated prothrombin complex concentrate) and recombinant porcine FVIII; immunosuppressive therapy (corticosteroids, rituximab, cyclophosphamide) is used to suppress autoantibody formation. Case reports and one series suggest that emicizumab can reduce the risk of bleeding and the requirement for hemostatic therapy until remission of AHA is achieved. Further, it may allow to postpone the start of immunosuppressive therapy or to use less intense regimens. However, the risk-benefit assessment of emicizumab in AHA is difficult because demographic and clinical characteristics are different compared with congenital hemophilia. Prospective clinical trials are needed before the use of emicizumab can be recommended in AHA.

Treatment of acquired thrombotic thrombocytopenic purpura without plasma exchange in selected patients under caplacizumab.

BACKGROUND: Acquired thrombotic thrombocytopenic purpura (aTTP) is a rare, life-threatening autoimmune thrombotic microangiopathy. Current standard of care is therapeutic plasma exchange, immunosuppression, and caplacizumab, an anti-von Willebrand factor nanobody, which is effective in treating aTTP episodes. PATIENTS/METHODS: Here we report on seven episodes of aTTP treated without plasma exchange in six female patients in Germany and Austria. Two episodes were initial presentations of aTTP; in five instances, patients experienced a relapse. In four episodes, moderate to severe organ dysfunction was observed; three cases presented with a mild course. All patients received caplacizumab immediately once aTTP was suspected or diagnosed, and plasma exchange was omitted based on shared decision making between patient and the treating physicians. RESULTS: We observed a rapid and robust increase of platelet counts already after the first dose of caplacizumab, leading to a doubling of platelet counts within 17 hours (median), platelet counts normalized (>150 G/L) after median 84 hours. Lactate dehydrogenase, as a surrogate parameter of organ damage, improved in parallel to the platelet counts, indicating resolving microangiopathy. CONCLUSIONS: In conclusion, in selected cases of acute bouts of aTTP, it seems feasible to delay or omit plasma exchange if platelet counts increase and organ function is stable after start of caplacizumab therapy.

Correlation of RAS-Pathway Mutations and Spontaneous Myeloid Colony Growth with Progression and Transformation in Chronic Myelomonocytic Leukemia-A Retrospective Analysis in 337 Patients.

Although the RAS-pathway has been implicated as an important driver in the pathogenesis of chronic myelomonocytic leukemia (CMML) a comprehensive study including molecular and functional analyses in patients with progression and transformation has not been performed. A close correlation between RASopathy gene mutations and spontaneous in vitro myeloid colony (CFU-GM) growth in CMML has been described. Molecular and/or functional analyses were performed in three cohorts of 337 CMML patients: in patients without (A, n = 236) and with (B, n = 61) progression/transformation during follow-up, and in patients already transformed at the time of sampling (C, n = 40 + 26 who were before in B). The frequencies of RAS-pathway mutations (variant allele frequency ≥ 20%) in cohorts A, B, and C were 30%, 47%, and 71% (p < 0.0001), and of high colony growth (≥20/105 peripheral blood mononuclear cells) 31%, 44%, and 80% (p < 0.0001), respectively. Increases in allele burden of RAS-pathway mutations and in numbers of spontaneously formed CFU-GM before and after transformation could be shown in individual patients. Finally, the presence of mutations in RASopathy genes as well as the presence of high colony growth prior to transformation was significantly associated with an increased risk of acute myeloid leukemia (AML) development. Together, RAS-pathway mutations in CMML correlate with an augmented autonomous expansion of neoplastic precursor cells and indicate an increased risk of AML development which may be relevant for targeted treatment strategies.

Bleeding and response to hemostatic therapy in acquired hemophilia A: results from the GTH-AH 01/2010 study.

Acquired hemophilia A (AHA) is due to autoantibodies against coagulation factor VIII (FVIII) and most often presents with unexpected bleeding. In contrast to congenital hemophilia, the patient's residual FVIII activity does not seem to correlate with the risk of bleeding as suggested from previous studies. Risk factors for bleeding have not been described. We used data from the prospective GTH-AH 01/2010 study to assess the risk of bleeding and the efficacy of hemostatic therapy. FVIII activity was measured at baseline and weekly thereafter. Bleeding events were assessed by treating physicians. A total of 289 bleeds were recorded in 102 patients. There were 141 new bleeds observed starting after day 1 in 59% of the patients, with a mean rate of 0.13 bleed per patient-week in weeks 1 to 12, or 0.27 bleed per patient-week before achieving partial remission. Weekly measured FVIII activity was significantly associated with the bleeding rate, but only achieving FVIII activity ≥50% abolished the risk of bleeding. A good World Health Organization performance status assessed at baseline (score 0 vs higher) was associated with a lower bleeding rate. Hemostatic treatment was reportedly effective in 96% of bleeds. Thus, the risk of new bleeds after a first diagnosis of AHA remains high until partial remission is achieved, and weekly measured FVIII activity may aid in assessing the individual risk of bleeding. These results will help to define future strategies for prophylaxis of bleeding in AHA.

Cross-reacting inhibitors against recombinant porcine factor VIII in acquired hemophilia A: Data from the GTH-AH 01/2010 Study.

BACKGROUND: Recombinant porcine factor VIII (rpFVIII, OBI-1, susoctocog alfa) is used for the treatment of acute bleeds in patients with acquired hemophilia A (AHA). Inhibitors in AHA can sometimes cross-react with rpFVIII. OBJECTIVES: To assess the frequency, strength, and determinants of cross-reactivity. PATIENTS/METHODS: Baseline samples from 70 patients of the prospective, observational cohort study GTH-AH 01/2010 were assessed for anti-human FVIII and anti-rpFVIII inhibitors using modified Nijmegen-Bethesda assays, as well as anti-human FVIII domain reactivity using enzyme-linked immunoassay (ELISA). RESULTS: Anti-human FVIII inhibitors were present in all samples ranging between 0.7 and 3891 Bethesda Units (BU)/mL. Inhibitors from 31 of 70 patients (44%) partially inhibited rpFVIII with anti-rpFVIII titers ranging between 0.5 and 471 BU/mL. Anti-rpFVIII titers were ≤5 BU in most patients. Patients with cross-reacting inhibitors, as compared to patients without, had significantly higher anti-human FVIII titers (27.8 versus 5.4 BU/mL) and lower baseline FVIII activity (<1 versus 2.6 IU/dL). The ratio between anti-rpFVIII to anti-human titers was highest for inhibitors involving the C1 domain. Cross-reactivity was very rare, if inhibitors reacted only with the C2 domain of FVIII (6%). An anti-human FVIII titer of >100 BU/mL predicted cross-reactivity with 97% likelihood, whereas an anti-human FVIII titer of <3.8 BU/mL predicted absent cross-reactivity with 90% likelihood. CONCLUSION: Cross-reacting inhibitors should be considered when choosing a treatment for bleeding patients with AHA. Cross-reactivity is frequent in patients with anti-human FVIII titers of >100 BU/mL.

The Austrian biodatabase for chronic myelomonocytic leukemia (ABCMML) : A representative and useful real-life data source for further biomedical research.

In the Austrian biodatabase for chronic myelomonocytic leukemia (ABCMML) clinicolaboratory real-life data have been captured from 606 CMML patients from 14 different hospitals over the last 30 years. It is the only large biodatabase worldwide in which functional methods such as semisolid in vitro cultures complement modern molecular methods such as next generation sequencing. This provides the possibility to comprehensively study the biology of CMML. The aim of this study was to compare patient characteristics with published CMML cohorts and to validate established prognostic parameters in order to examine if this real-life database can serve as a representative and useful data source for further research. After exclusion of patients in transformation characteristics of 531 patients were compared with published CMML cohorts. Median values for age, leukocytes, hemoglobin, platelets, lactate dehydrogenase (LDH) and circulating blasts were within the ranges of reported CMML series. Established prognostic parameters including leukocytes, hemoglobin, blasts and adverse cytogenetics were able to discriminate patients with different outcome. Myeloproliferative (MP) as compared to myelodysplastic (MD)-CMML patients had higher values for circulating blasts, LDH, RAS-pathway mutations and for spontaneous myelomonocytic colony growth in vitro as well as more often splenomegaly. This study demonstrates that the patient cohort of the ABCMML shares clinicolaboratory characteristics with reported CMML cohorts from other countries and confirms phenotypic and genotypic differences between MP-CMML and MD-CMML. Therefore, results obtained from molecular and biological analyses using material from the national cohort will also be applicable to other CMML series and thus may have a more general significance.