scholarly journals Relapse Prediction Model for Immune-Mediated Thrombotic Thrombocytopenic Purpura

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 8-9
Author(s):  
Camila Masias ◽  
Shangbin Yang ◽  
Senthil Sukumar ◽  
Alcinda Flowers ◽  
Haiwa Wu ◽  
...  
Keyword(s):  
Complement Activation ◽  
Research Funding ◽  
Factor Model ◽  
Factor Models ◽  
Preemptive Therapy ◽  
Adamts13 Activity ◽  
Thrombocytopenic Purpura ◽  
Asymptomatic Patients ◽  
Immune Mediated ◽  
Risk Of Relapse

Background: Immune mediated thrombotic thrombocytopenic purpura (iTTP) is defined by thrombocytopenia and microangiopathic hemolytic anemia caused by severely deficient ADAMTS13 activity (<10%). After resolution of their initial episode, patients remain at risk for relapse. Relapse is most common during the first year, but can occur at any point in their lives. In asymptomatic patients, severely deficient ADAMTS13 activity in remission has been shown to be a risk factor for relapses and can guide consideration of preemptive therapy with Rituximab. However, severely deficient ADAMTS13 activity alone does not uniformly lead to relapse, and patients with non-deficient ADAMTS13 activity in remission may still relapse in the following months. The aim of this study was to develop a multivariable model to identify patients at high risk of relapse, using other biomarkers known to have a role in the pathophysiology of iTTP. Patients/Methods: This analysis utilized samples from patients enrolled in the Ohio State University TMA registry beginning in 2003 until 2014. Patients were followed every 3 months to monitor for relapse and for the development of long-term complications. Clinical data (CBC, chemistry, LDH, ADAMTS13 biomarkers) were obtained on each visit to confirm remission in addition to research samples. Clinical and demographic data in addition to biomarkers of complement activation that were performed on banked samples were used to develop a model to quantify the risk for relapse in the following 3 months. A Lasso logistic regression model (Tibshirani et al 1996) with relapse in the following 3 months as the response variable using the R package glmnet (https://cran.r-project.org/web/packages/glmnet/index.html) was used to identify those variables most predictive of relapse from the 17 studied (Table 1). The data from all subjects were split into training data (75%) and testing data (25%) to develop and subsequently test the performance of the model. The final predictors were then standardized to develop the final model and the program to predict the risk of relapse (%) in the following 3 months. Results: Data from a total of 131 patient encounters from 42 patients in a clinical remission were included in the study to develop the statistical model (Table 2). 31(75.6%) were White and 10 (24.4%) were African American. The average age was 42 (18-69), and 31 (75.6%) were women. The median number of encounters from each patient was 2 (range, 1 to 10). From these 131 encounters, 39 relapses occurred in 20 patients over the next 3 months following their clinic visit. The 39 relapse encounters were compared to the 92 encounters where no relapse occurred to develop the model. The performance of both the 11-factor and 6-factor models are shown in Table 3. Given the comparable data in terms of the AUC, sensitivity and specificity to the 11-factor model to predict relapse, the 6-factor model was judged to be more practical given the fewer number of variables. Both the 11-factor and 6-factor models performed better than the ADAMTS13 activity alone. In this model, the presence of ULVWF multimers, increased levels of LDH, complement activation as measured by C3a (log transformed), a lower ADAMTS13 activity (log transformed), ADAMTS13 antigen (log transformed), and younger age increased the risk for relapse. These variables would be entered into the model with the result being read out as a percent risk for relapse in the following 3 months as described in the hypothetical examples in Table 4. Conclusion: Utilizing a model that includes a combination of biomarkers in asymptomatic patients in remission from iTTP provides more accurate identification of patients at increased risk of relapse in the next 3 months, when compared to using the ADAMTS13 activity alone. This model would allow physicians to initiate preemptive therapy with rituximab to patients at the greatest risk for relapse, and potentially avoiding therapy in patients whose risk may be lower than what would be predicted by the ADAMTS13 activity alone. Disclosures Cataland: Ablynx/Sanofi: Consultancy, Research Funding; Alexion: Consultancy, Research Funding.

scholarly journals Severely Deficient ADAMTS13 Activity Predicts Relapse of Immune-Mediated Thrombotic Thrombocytopenic Purpura in Pregnancy

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1098-1098
Author(s):  
Camila Masias ◽  
Krista Carter ◽  
Haiwa Wu ◽  
Shangbin Yang ◽  
Alcinda Flowers ◽  
...  
Keyword(s):  
Thrombotic Thrombocytopenic Purpura ◽  
Research Funding ◽  
The Other ◽  
Clinical Relapse ◽  
Adamts13 Activity ◽  
Thrombocytopenic Purpura ◽  
Second Hit ◽  
Immune Mediated ◽  
Risk Of Relapse ◽  
In Pregnancy

Background: It is commonly accepted that severely deficient ADAMTS13 activity in remission increases the risk for relapse, but relapse in severely deficient ADAMTS13 activity in patients with immune-mediated thrombotic thrombocytopenic purpura (iTTP) is not uniform. Mouse models and published studies have suggested that a "second hit" is required in addition to severely deficient ADAMTS13 activity to lead to clinical relapse. Our initial published experience led us to preliminarily conclude that pregnancy could serve as the second hit in addition to severely deficient ADAMTS13 activity and lead to relapse. The aim of this study was to evaluate the risk of relapse and outcomes of pregnant patients with a diagnosis of iTTP. Methods: Since the initiation of the Ohio State University TTP Research Program in 2003, patients were consented at enrollment and followed longitudinally in our IRB approved iTTP registry, usually every three to six months. During pregnancy, patients were seen and CBC, LDH and ADAMTS13 activity were obtained monthly. Due to prior reports of iTTP relapses during pregnancy, it is our practice to offer prophylaxis with cyclosporine to pregnant patients with a diagnosis of iTTP and severely deficient ADAMTS13 activity. The clinical diagnosis of iTTP (defined as thrombocytopenia, microangiopathic hemolytic anemia, without an alternative explanation was confirmed by severely deficient ADAMTS13 activity (<10%) in all cases. ADAMTS13 activity was determined using a SELDI-TOF mass-spectrometer-based method. Results: During the study time, we have followed 11 pregnancies from eight patients with iTTP. Two pregnancies occurred at the time of their initial diagnosis, and nine pregnancies occurred during follow up. Two patients were black, nine were white. Median age was 26 ( range 20-36). Of the nine pregnancies in patients with a previous diagnosis of iTTP, three resulted in relapses, two in the same patient; one at 23 weeks that resulted in fetal demise, and the next one occurred one week after delivery at 36 weeks. The other patient relapsed at 35 weeks and the baby was delivered early at 36 weeks. All relapses were preceded by a documented ADAMTS13 <10%, with a normal platelet count, LDH and no associated symptoms, while none of the other pregnancies had a documented ADAMTS13 <10% (Figure 1). Interestingly, one of the relapses occurred while the patient was taking cyclosporine during pregnancy as preemptive therapy to prevent relapses. She initially responded to therapy with an increase in her ADAMTS13 activity but subsequently lost the response which preceded her relapse post-partum. Conclusions: Pregnancy in patients with a diagnosis of iTTP is a risk factor for iTTP relapse. To our knowledge, this is the first report of the relationship between ADAMTS13 and the risk of relapse during pregnancy. Our results demonstrate that severely deficient ADATMS13 activity uniformly leads to relapse in pregnancy. It also highlights the clinical relevance of monitoring ADAMTS13 activity closely in patients with a history of iTTP that become pregnant. Figure 1 Disclosures Masias: Rigel Pharmaceuticals: Consultancy. Cataland:Alexion: Consultancy, Research Funding; Ablynx/Sanofi: Consultancy, Research Funding. OffLabel Disclosure: the use of cyclosporine for prevention of TTP relapses

scholarly journals Presenting ADAMTS13 Antigen Level Correlates with Clinical Outcome in Acute Thrombotic Thrombocytopenic Purpura

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1365-1365
Author(s):  
Ferras Alwan ◽  
Chiara Vendramin ◽  
Katy Langley ◽  
Debra Ellis ◽  
Mari Thomas ◽  
...  
Keyword(s):  
Clinical Outcome ◽  
Thrombotic Thrombocytopenic Purpura ◽  
Hemolytic Anemia ◽  
Research Funding ◽  
Disease Process ◽  
Adamts13 Activity ◽  
Antigen Level ◽  
Thrombocytopenic Purpura ◽  
Immune Mediated ◽  
Increased Risk

Abstract Background: Acute immune-mediated Thrombotic Thrombocytopenic Purpura (TTP) is a life-threatening disorder caused by acquired antibodies to the Von Willebrand factor cleaving protease ADAMTS13. Its prevalence has been estimated at four to thirteen cases per million per year and is characterized by hemolytic anemia, thrombocytopenia and multiorgan microthrombi. Untreated, mortality has been documented at 90% but even with treatment, it remains around 10-20%. Plasma Exchange (PEX) is the mainstay of treatment but immunosuppressive/immunomodulatory therapy is often also required. Whilst understanding of the disease process has increased greatly in recent times and a number of factors been implicated as possible markers of disease severity, there has been little evaluation of the effect of ADAMTS13 antigen levels on clinical outcome. Since January 2009, the United Kingdom TTP registry has been collecting information on all acute presentations of TTP across the country. Aims: A prospective study to evaluate the effect of the ADAMTS13 antigen titer on clinical outcomes in acute, immune-mediated TTP. Methods: Acute, immune-mediated TTP was defined as microangiopathic hemolytic anemia and thrombocytopenia with ADAMTS13 activity <10% (FRETS vWF-73 assay, NR: 64-134%) or 10-20% with detectable anti-ADAMTS13 IgG. Congenital TTP cases were excluded. ADAMTS13 antigen was quantified using an in-house ELISA technique (normal range 74-134%). Results: There were 312 acute episodes of acquired TTP involving 292 patients over 87 months. Median ADAMTS13 activity was <5% (range <5% - 19%). Median ADAMTS13 antigen at presentation was 4% (range 0.5 - 146%). 72% of patients had antigen levels<10% at presentation. The mortality rate was 10.3% (died = 32). Median ADAMTS13 antigen levels were significantly lower in patients who died compared to survivors (survivors 4.2% (range 0.5-146%) vs died 1.6% (0.5-21.5%), p=0.0007). Mortality increased with lower ADAMTS13 antigen levels: those with an antigen level in the lowest quartile (antigen <1.5%) had a mortality of 18% compared with 3.8% for those in the highest quartile (antigen >11.65%) (p=0.0046). Patients with relapsed TTP had significantly higher presenting ADAMTS13 antigen levels compared to new presentations (new presentation 3.25% vs relapse 10%, p<0.0001). Patients with ADAMTS13 antigen <4% required more plasma exchanges to remission defined as platelet count of 150x109/l (median 8 exchanges vs 10, p=0.036). This cohort also had a significantly higher median anti-ADAMTS13 IgG titer (ADAMTS13 antigen <4%, median IgG 58% (range 1-174%) vs antigen >4% median IgG 28% (5-189%), p<0.0001) and was more likely to have a markedly elevated cardiac troponin (five times the upper limit of normal) at presentation (p=0.009). Conclusion: ADAMTS13 antigen levels appear to correlate with the clinical outcome in acute, immune-mediated TTP. A presenting antigen level below 4% was associated with an increased risk of mortality, more refractory disease and a greater prevalence of severe cardiac events. Disclosures Alwan: Octapharma: Research Funding; Ablynx: Research Funding. Scully:Alexion Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding.

scholarly journals ADAMS-TS13 Inhibitor Level and Risk of Relapse in Acquired Idiopathic Thrombotic Thrombocytopenic Purpura

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 1012-1012
Author(s):  
Annum Faisal ◽  
Darla Liles ◽  
Yara Park ◽  
Meera Sridharan
Keyword(s):  
North Carolina ◽  
Platelet Count ◽  
Thrombotic Microangiopathy ◽  
Final Analysis ◽  
Refractory Disease ◽  
Adamts13 Activity ◽  
Thrombocytopenic Purpura ◽  
Inhibitor Level ◽  
Inhibitor Titer ◽  
Risk Of Relapse

Abstract Introduction: Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy due to reduced activity of ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 motif, 13). This disorder can be due to a congenital deficiency state or be acquired (immune TTP (iTTP)) due to an antibody which either inhibits or causes clearance of ADAMTS13. The aim of our study was to determine whether ADAMTS13 inhibitor titer at initial presentation could serve as a predictor of refractory disease and relapse in iTTP. We also measured clinical outcomes across different gender and racial subgroups. Methods: The United States Thrombotic Microangiopathy (USTMA) iTTP registry was used to extract patient information for two academic institutions in Eastern North Carolina. Descriptive statistics were used to analyze the data. The first iTTP episode recorded in the data base was used as the index episode. All patients included in the final analysis had an ADAMTS13 activity of &lt;10%. An inhibitor level of 5 Bethesda units was arbitrarily chosen as the cutoff between low (&lt;5) and high (&gt;/5) inhibitor level. Response time was defined as the number of days of plasma exchange (PEX) required to achieve a platelet count of 150,000 for two consecutive days. Relapse was defined as occurrence of a new episode of iTTP 30 days after achievement of response. Refractory disease was defined as persistence of thrombocytopenia or absence of a sustained platelet count increment or platelet counts of &lt; 50,000 despite 4-7 days of plasma exchanges and steroid treatment. Rituximab resistance was defined as lack of platelet recovery to more than 150,000 within 11 to 14 days of administration of the first dose of Rituximab. Results: A total of 161 patients with iTTP were identified. Ten patients had ADAMTS13 activity &gt;10% and 15 patients did not have a reported inhibitor level. These subjects were not included in the final analysis. The cohort had 28% male (n =38/136) and 72% (n=98/136) female patients. There were more African American patients 73% (n=99/136) than Caucasians 24% (n=32/136). There were also 2 Hispanic, 1 Native American and 2 patients with unidentified race. Median ADAMTS3 inhibitor titer was 1.05 (Range 0-87). Forty three patients with ADAMTS13 activity &lt;10 % had an inhibitor level of 0 (i.e undetectable).They were included in the low inhibitor group. Overall, 88% patients (n=120/136) had low inhibitor level and only 12% (n=16/136) had a high inhibitor. Thirteen percent females (n=13/98) and 8% (n=3/38) males had a high inhibitor level (p=0.387). Fourteen percent (n=14/99) African Americans and 6 % (n=2/32) Caucasians had a high inhibitor, p=0.23. In the low inhibitor group 30% (n=36/120) patients suffered at least one episode of relapse whereas 31% (n=5/16) had relapsed in the high inhibitor group. The median time to response was 6 days (range 1-76) in the low inhibitor group and 7 days (range 4-20) in the high inhibitor group (p=0.61). While looking at the various subgroups, median time to response for males was 6 days (range 4-21), females 6 days (range 1-76) , African Americans 6 days (range 3-29) , and Caucasians 6 days (range 1-76). The frequency of refractory disease was 31 % (n=5/16) in the high inhibitor group and 29% (n=34/119) in the low inhibitor group. At the time of enrollment in the registry, Rituximab was not a part of first line therapy. Only 26 out of 136 patients had received Rituximab. In the low inhibitor group 5 patients displayed Rituximab resistance whereas there were no patients in the high inhibitor group with Rituximab resistance. Conclusion: When evaluating patients presenting with iTTP in two centers in North Carolina, no correlation was found between a high inhibitor levels of &gt;/ 5 Bethesda units and risk of relapse or refractory disease. A larger study is needed to evaluate this further. Disclosures No relevant conflicts of interest to declare.

scholarly journals The HLA Variant rs6903608 Is Associated with Disease Onset and Relapse of Immune-Mediated Thrombotic Thrombocytopenic Purpura in Caucasians

2020 ◽  
Vol 9 (10) ◽  
pp. 3379
Author(s):  
Ilaria Mancini ◽  
Elisa Giacomini ◽  
Silvia Pontiggia ◽  
Andrea Artoni ◽  
Barbara Ferrari ◽  
...  
Keyword(s):  
Thrombotic Thrombocytopenic Purpura ◽  
Risk Allele ◽  
Absolute Risk ◽  
Disease Onset ◽  
Close Monitoring ◽  
Reference Allele ◽  
Thrombocytopenic Purpura ◽  
Immune Mediated ◽  
The Impact ◽  
Risk Of Relapse

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare, life-threatening thrombotic microangiopathy caused by severe ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin motifs 13) deficiency, recurring in 30–50% of patients. The common human leukocyte antigen (HLA) variant rs6903608 was found to be associated with prevalent iTTP, but whether this variant is associated with disease relapse is unknown. To estimate the impact of rs6903608 on iTTP onset and relapse, we performed a case-control and cohort study in 161 Italian patients with a first iTTP episode between 2002 and 2018, and in 456 Italian controls. Variation in rs6903608 was strongly associated with iTTP onset (homozygotes odds ratio (OR) 4.68 (95% confidence interval (CI) 2.67 to 8.23); heterozygotes OR 1.64 (95%CI 0.95 to 2.83)), which occurred over three years earlier for each extra risk allele (β −3.34, 95%CI −6.69 to 0.02). Of 153 survivors (median follow-up 4.9 years (95%CI 3.7 to 6.1)), 44 (29%) relapsed. The risk allele homozygotes had a 46% (95%CI 36 to 57%) absolute risk of relapse by year 6, which was significantly higher than both heterozygotes (22% (95%CI 16 to 29%)) and reference allele homozygotes (30% (95%CI 23 to 39%)). In conclusion, HLA variant rs6903608 is a risk factor for both iTTP onset and relapse. This newly identified biomarker may help with recognizing patients at high risk of relapse, who would benefit from close monitoring or intensified immunosuppressive therapy.

N-Acetylcysteine Treatment in Two Patients with Relapsed Thrombotic Thrombocytopenic Purpura Increased ADAMTS13 Activity, Free Thiol Concentration in Plasma, and Inhibited Platelet Activation

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 239-239
Author(s):  
Junmei Chen ◽  
Tahsin Özpolat ◽  
Colette Norby ◽  
Jennie Le ◽  
Minhua Ling ◽  
...  
Keyword(s):  
Platelet Count ◽  
Plasma Exchange ◽  
Platelet Activation ◽  
Research Funding ◽  
Specific Activity ◽  
High Dose ◽  
Adamts13 Activity ◽  
Thrombocytopenic Purpura ◽  
Platelet Counts ◽  
Free Thiol

Abstract Introduction: Thrombotic thrombocytopenic purpura (TTP) is a catastrophic and potentially fatal disorder caused by systemic microvascular thrombosis due to von Willebrand factor (VWF)-platelet thrombi. TTP is caused by congenital or acquired deficiency of the plasma metalloprotease ADAMTS13. Based on an earlier study (Chen J et al., J Clin Invest 2011, 121:593-603), we proposed N-acetylcysteine (NAC) as an adjunct treatment for TTP. This study showed that NAC reduced the size and activity of VWF in vitro in human plasma and in vivo in a TTP mouse model. In 2013 and 2014, two case reports described treatment of refractory TTP patients with NAC, one receiving a low dose of NAC [300 mg/kg (total 15 g) for the 1st 24 hrs, followed by 2.5 g/day for two weeks concurrently with plasma exchange] (Shortt J et al., N Engl J Med 2013, 368: 90-92; Shortt J et al., Transfusion 2014, 54:2362-2363) and the other receiving high-dose NAC [300 mg/kg/day (11 g/day) for 10 days between plasma exchanges] (Li GW et al. Transfusion 2014, 54: 1221-1224). The patient treated with high-dose NAC improved rapidly (the patient woke up from coma 18 hr after NAC treatment was initiated), but the patient treated with lower dose NAC did not appear to respond. Thus, it is as yet unclear whether NAC is an effective treatment for TTP. Therefore, more clinical studies and detailed analyses are required to examine the effects of NAC in TTP patients. Here we report the results of clinical and biochemical studies on two patients with relapsed TTP treated with NAC. Before, during, and after NAC treatment, we determined the concentrations of NAC, cysteine, and glutathione in plasma; VWF concentration, multimer structure, and functions; ADAMTS13 concentration and activity; and platelet counts and activation status (P-selectin expression and phosphatidylserine exposure). Methods: Two females with a history of prior episodes of TTP presented with acute TTP [ADAMTS13 < 10%, positive for ADAMTS13 inhibitors, platelet count ≤ 10,000/uL, lactate dehydrogenase (LDH) > 600 IU/L] and both were treated with NAC per IRB-approved protocol [150 mg/kg bolus over 1 hr and 150 mg/kg as continuous infusion until the next therapeutic plasma exchange (TPE)]. They received daily TPE until their platelet counts normalized, and intravenous NAC during days 2-5. Blood was collected daily for 8 days for research assays. ADAMTS13 concentrations in patient plasma were measured by ELISA. ADAMTS13 activity was measured using HRP-conjugated A2 peptide substrate (Wu J-J et al. J Thromb Haemost 2006, 4:129-136). Concentrations of NAC, total cysteine, and total free thiols (free thiol cysteine and free thiol NAC) in plasma were determined by mass spectrometry. Plasma VWF multimer patterns were analyzed by 1.5% agarose gel electrophoresis followed by western blotting with an HRP-conjugated polyclonal VWF antibody. Platelets in whole blood were labeled for platelet markers (CD41a or CD42b) together with one of the activation markers, P-selectin or phosphatidylserine (lactadherin). The labeled platelets were analyzed by flow cytometry. Results: Platelet counts in both patients started to increase 1 day after NAC infusion and continued to increase after discontinuation of NAC and TPE. After NAC infusion, the free thiol concentration (NAC and cysteine) in plasma increased 4 and 59 fold in patients 1 and 2, respectively. This was accompanied by increasing ADAMTS13 specific activity (ADAMTS13 activity/ADAMTS13 antigen). In patient 1, the specific activity increased from 127% (prior to NAC infusion but after TPE) to 270% during NAC infusion; in patient 2, the specific activity increased from 56% to 86%. In patient 1, the VWF multimer size decreased during NAC treatment and the VWF multimers migrated slightly faster. NAC also appeared to inhibit platelet activation. Before NAC infusion, the platelets in both patients were positive for phosphatidylserine (PS, > 30%) and P-selectin (> 15%), compared to 2% and 5%, respectively, in a normal control. The percentages of PS- and P-selectin-positive platelets decreased to less than 18% and 10% respectively, during NAC treatment. Summary: NAC treatment of two patients with TTP in conjunction with TPE was well tolerated and associated with recovery of platelet count and LDH, increased ADAMTS13 specific activity and total free thiol concentration in plasma, reduced platelet activation, and decreased VWF multimer size in one patient. Disclosures Konkle: CSL Behring: Consultancy; Pfizer: Consultancy; Baxalta: Consultancy, Research Funding; Biogen: Consultancy, Research Funding; Octapharma: Research Funding; Novo Nordisk: Consultancy.

scholarly journals Next-Generation Sequencing of HLA Loci Identifies Predisposing and Protective Factors for Immune-Mediated Thrombotic Thrombocytopenic Purpura in a Japanese Population

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1085-1085
Author(s):  
Kazuya Sakai ◽  
Masataka Kuwana ◽  
Hiroto Kojima ◽  
Hidenori Tanaka ◽  
Masayuki Kubo ◽  
...  
Keyword(s):  
Risk Factors ◽  
Next Generation Sequencing ◽  
Japanese Population ◽  
Hemoglobin Level ◽  
P Value ◽  
Adamts13 Activity ◽  
Next Generation ◽  
Thrombocytopenic Purpura ◽  
Immune Mediated ◽  
Generation Sequencing

Background Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is an autoimmune disorder caused by neutralizing anti-ADAMTS13 autoantibodies. This condition leads to life-threatening microvascular thrombi in systemic organs due to an imbalance between ADAMTS13 and von Willebrand factor. While several European groups reported that HLA-DRB1*11 was one of the strongest genetic risk factors for iTTP, no large-scale studies have analyzed which HLA alleles convey greater risk for iTTP in genetically isolated Japanese. Therefore, we analyzed ten HLA loci using next-generation sequencing. Materials and Methods We performed a prospective cohort study among Japanese patients with iTTP. The diagnosis of iTTP was suspected in cases of thrombocytopenia and hemolytic anemia with unknown cause, and was confirmed by both severe deficiency of ADAMTS13 (below 10% of normal) and the presence of anti-ADAMTS13 inhibitor. Fifty-six patients with iTTP from 19 institutes were enrolled in this study from August 2017 to March 2019, and 52 patients were finally eligible. An EDTA-treated serum sample was obtained from each patient at enrollment, and was analyzed via next-generation sequencing to identify the HLA alleles at following loci: A, B, C, DRB1, DRB3/4/5, DQA1, DQB1, and DPB1. Then, we compared allele frequencies at each locus in iTTP patients with those in a healthy Japanese population as reported by Nakajima et al in 2001. Additionally, we collected data on laboratory tests and clinical response to treatment during the acute phase. The HLA allele frequency of patients with iTTP and controls were compared by Fisher's exact test, and Bonferroni correction was applied to observed P-values. In this study, we multiplied the P-value by the number of alleles in each locus whose frequency was more than 1% in control to calculate the corrected P-value (Pc). This study was approved by the IRB of each referring institute. Results The male/female ratio of enrolled patients was 22/30. The median age was 58 years (range: 1-81). Based on the underlying disease, iTTP patients were classified as having primary TTP (n=38), autoimmune disease (n=12), malignancy (n=1), or acute pancreatitis (n=1). Plasma levels of ADAMTS13 activity were less than 3% in all cases, and the median concentration of ADAMTS13 autoantibodies was 2.5 Bethesda units/mL (range: 0.5-113). All patients showed severe thrombocytopenia (median platelet count: 12×109/L) and hemolytic anemia (median hemoglobin level: 8.0 g/dL, and median LDH level: 995 U/L). During the acute phase, 49 of 52 patients received combination treatment with plasma exchange (PEX) using fresh frozen plasma and corticosteroids. Additional immunosuppressants were administered in several cases, as follows: rituximab in 23 cases, cyclosporin A in 7 cases, cyclophosphamide in 5 cases, vincristine in 3 cases, and mycophenolate mofetil in 1 case. The median number of PEX treatments was 11 (range: 3-42). The allele frequencies in iTTP patients and controls are shown in Table 1. Regarding HLA class II alleles (DRB1, DRB3/4/5, DQA1, and DQB1), we identified the following alleles as risk factors for iTTP in the Japanese population: DRB1*08:03 (odds ratio [OR]: 3.06, Pc=0.005), DRB3/4/5*blank (OR: 2.3, Pc=0.007), DQA1*01:03 (OR: 2.25, Pc=0.006), and DQB1*06:01 (OR: 2.41, Pc=0.003). The estimated haplotype consisting of these 4 alleles was more frequent in the iTTP group than in the control group (30.8% vs. 6.0%, Pc<0.001). By contrast, DRB5*01:01 was associated with a reduced risk of iTTP (OR: 0.23, Pc=0.03). Among the A, B, C, and DPB1 loci, no significant difference was found between the 2 groups. Surprisingly, DRB1*11 was not identified as a risk factor for iTTP in Japanese, unlike in Caucasians. Additional analysis showed that this haplotype did not influence platelet count, hemoglobin level, lactate dehydrogenase level, ADAMTS13 activity, or the concentration of ADAMTS13 autoantibodies. Conclusion We found that a Japanese-specific haplotype, DRB1*08:03-DRB3/4/5(blank)- DQA1*01:03-DQB1*06:01, was a significant risk factor for iTTP in a Japanese population, and that DRB5*01:01 was a protective factor against iTTP development. Disclosures No relevant conflicts of interest to declare.

scholarly journals Open ADAMTS13, induced by antibodies, is a biomarker for subclinical immune-mediated thrombotic thrombocytopenic purpura

Blood ◽  
2020 ◽  
Author(s):  
Elien Roose ◽  
An-Sofie Schelpe ◽  
Edwige Tellier ◽  
György Sinkovits ◽  
Bérangère S Joly ◽  
...  
Keyword(s):  
Thrombotic Thrombocytopenic Purpura ◽  
Adamts13 Activity ◽  
Thrombocytopenic Purpura ◽  
Follow Up Study ◽  
Open Conformation ◽  
Immune Mediated ◽  
Long Term Follow Up ◽  
Donor Plasma

Recently, we showed that during the acute phase of immune-mediated thrombotic thrombocytopenic purpura (iTTP), ADAMTS13 circulates in an open conformation. Although the cause of this conformational change in acute iTTP remains elusive, ADAMTS13 is mainly closed in iTTP patients (i) in remission with an ADAMTS13 activity &gt;50% and undetectable anti-ADAMTS13 autoantibodies, and (ii) after rituximab treatment, suggesting a role for anti-ADAMTS13 autoantibodies. Therefore, IgGs from 18 acute iTTP patients were purified and added to closed ADAMTS13 in healthy donor plasma. This resulted in open ADAMTS13 in 14/18 (78%) samples, proving that indeed anti-ADAMTS13 autoantibodies can induce an open ADAMTS13 conformation. To further elucidate the conformation of ADAMTS13 in iTTP patients, we studied a novel iTTP patient cohort (n=197) that also included plasma samples of iTTP patients in remission where ADAMTS13 activity was &lt;50%. The open ADAMTS13 conformation was not only found during acute iTTP but also in patients in remission with an ADAMTS13 activity &lt;50% and in half of the patients with an ADAMTS13 activity &gt;50%, although free anti-ADAMTS13 autoantibodies were not always detected. Thus open ADAMTS13 is not only a hallmark of acute iTTP, but also a novel biomarker to detect subclinical iTTP in patients in remission. Finally, a long term follow-up study in one iTTP patient showed that the open conformation precedes a severe drop in ADAMTS13 activity. In conclusion, we have shown that anti-ADAMTS13 autoantibodies from iTTP patients induce an open ADAMTS13 conformation. Most importantly, an open ADAMTS13 conformation is a biomarker for subclinical iTTP and could become an important tool in TTP management.

scholarly journals Complement Activation May Trigger the Onset of Thrombotic Thrombocytopenic Purpura in Patients with Severe ADAMTS13 Deficiency

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 600-600 ◽  
Author(s):  
Xiao-Hui Hu ◽  
Jialing Bao ◽  
Yoshiyasu Ueda ◽  
Takashi Miwa ◽  
Wenchao Song ◽  
...  
Keyword(s):  
Thrombotic Thrombocytopenic Purpura ◽  
Complement Activation ◽  
Factor H ◽  
Severe Thrombocytopenia ◽  
Complement Factor ◽  
Healthy Controls ◽  
Adamts13 Activity ◽  
Activation Markers ◽  
Thrombocytopenic Purpura ◽  
Adamts13 Deficiency

Abstract Thrombotic thrombocytopenic purpura (TTP), a potential fatal syndrome, is often associated with severe deficiency of plasma ADAMTS13 activity, either resulting from ADAMTS13 mutations or acquired anti-ADAMTS13 autoantibodies that inhibit plasma ADAMTS13 activity. Patients with severe ADAMTS13 do not always have TTP signs and symptoms, which often occur following infections or inflammatory responses. The mechanism of TTP flare is not fully understood. In the present study, complement activation markers (iC3b, C5b, Bb, and C4b) were determined by enzyme-linked absorbent assays (ELISA) in the initial plasmas (prior to plasma exchange) of 20 patients with acquired TTP with severe ADAMTS13 deficiency (less than 20% of normal) and plasmas from 20 healthy controls. Of 20 TTP patients, 19 exhibited positive inhibitor in the 50:50 mixing study. Plasma levels of iC3b (1,000 ± 1,062 ng/ml), sC5b-9 (1,342±867 ng/ml), and Bb (38.2±47.7 ng/ml), as well as C4b (74.3±49.5 ng/ml) in acquired TTP patients were significantly higher than those in healthy controls (p value less than 0.01) These results indicate that complement activation in both classic and alternative pathways is a common phenomenon in patients with acquired autoimmune TTP. To demonstrate the causative effect of complement activation in TTP, we turned to our Adamts13 null mice. C57BL/6 (Adamts13-/-) mice are resistant to the development of spontaneous and Shigatoxin-induced TTP syndrome. When injected with a murine specific monoclonal antibody against complement factor H (CFH) (800 micro grams/mouse), which inhibits binding of circulating CFH to endothelial cells and C3b, Adamts13-/- mice (C57BL/6) developed more severe thrombocytopenia and anemia than wild type mice did within 6 days without additional challenge. However, renal insufficiency manifested by the increase of plasma BUN concentration was similar in both groups (Fig. 1). These results indicate that complement activation through an alternative pathway, following antibody-mediated inhibition of CFH or other complement regulatory components, may trigger the onset of TTP in light of severe ADAMTS13 deficiency. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Relapsing Thrombotic Thrombocytopenic Purpura: A Single Center Experience

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3732-3732
Author(s):  
Arielle L Heeke ◽  
Craig M. Kessler ◽  
Catherine Broome
Keyword(s):  
Disease Control ◽  
Thrombotic Thrombocytopenic Purpura ◽  
Research Funding ◽  
Activity Level ◽  
High Dose ◽  
Adamts13 Activity ◽  
Thrombocytopenic Purpura ◽  
The Mean ◽  
Term Management

Abstract Thrombotic thrombocytopenic purpura (TTP) is due to a severe deficiency of the von Willebrand factor (vWF) cleaving serine metalloprotease ADAMTS13 and is most commonly diagnosed in adults due to autoantibodies against ADAMTS13. Standard therapy includes plasma exchange (PEX) until platelet counts normalize plus concurrent high dose corticosteroids. In refractory cases, weekly pulse Rituximab for 4 doses is often added. Successful long-term management of relapsing patients beyond these treatments is unclear, in part because the mechanisms for relapsing TTP are unknown. Dysfunctional immunoregulatory systems likely play a role in relapsing disease. Several case series have described disease control following bortezomib therapy (Patriquin 2016). Other immunomodulators including complement pathway and tyrosine kinase inhibitors may prove to offer benefit. Further, supplementing PEX with N-acetylcysteine (Rottenstreich 2016) & Caplacizumab (anti-vWF humanized immunoglobulin) (Peyvandi 2016) has shown promising preliminary clinical results when used to treat an acute episode. Effects on relapse rates with these treatments have not been fully evaluated. Eight cases of relapsing TTP were identified at MedStar Georgetown University Hospital May 2004 to July 2016. Relapsing TTP was defined as recurrent episode(s) of thrombocytopenia, microangiopathic hemolysis, and confirmed ADAMTS13 activity levels <10% following remission from the initial TTP episode. Retrospective chart review was completed to evaluate demographic and clinicopathologic features, laboratories and treatment at relapse(s), and clinical outcomes. In our 8 patient cohort, 75% are female (6/8), 62.5% are African American (AA) (5/8), and the mean age at initial TTP diagnosis is 35.38 (range 16-67). The mean number of relapses is 3.38 (range 2-9) with a mean platelet nadir of 45,000/mcL. All patients remain alive. Two are ANA positive, 1 with known systemic lupus erythematosus (SLE) and 1 with suspected SLE. None are HIV positive, and none endorse a family history of TTP. Four identified infections as triggers for their TTP, 1 patient developed TTP during pregnancy and hormonal fertility treatments, and 3 had no identifiable triggers. All had an increased titer of ADAMTS13 inhibitor (Bethesda titer range 0.7 - >8) at the time of relapse(s). Normalization of ADAMTS13 activity was confirmed in most following treatment (n=6), with a mean ADAMTS13 activity level between relapses of 50.5% (range 32-88%). At the time of each relapse, all patients underwent daily PEX with fresh frozen plasma plus high dose corticosteroids for at least 5 days (range 5-21 days), with some requiring gradual PEX weaning over 1-4 weeks and steroid tapering over months based on lab parameters. Two relapsed quickly after PEX discontinuation, both in the setting of systemic illness (lupus flare, cholecystitis). Sequelae of TTP (neurologic, renal, hematologic anomalies) resolved with treatment. All patients received Rituximab therapy during the 1st or 2nd relapse. For the majority (87.5%, 7/8), this intervention did not lead to long-term remission, although 100% (2/2) who transitioned to prophylactic bolus Rituximab every 6 months post splenectomy achieved long-term disease control. It is difficult to distinguish whether remission resulted from maintenance Rituximab, the splenectomy, or a combination of the two. Patients who underwent splenectomy were vaccinated and have not had difficulty with infections or thrombosis. In conclusion, our cohort of patients with relapsing TTP all had documented ADAMTS13 inhibitors and acutely responded to daily PEX (most requiring PEX wean based on lab parameters) plus high dose corticosteroids. Although Rituximab therapy during initial relapse did not offer a high percentage of long-term remissions, the addition of prophylactic Rituximab every 6 months post splenectomy has achieved long-term control in 2 patients. In our cohort the majority are AA, suggesting genetic susceptibility. HLA/immune transcript levels and ribosomal gene signatures may correlate with TTP disease activity and risk for relapse (Edgar 2015), and could be used to identify high-risk patients in need of more intensive therapy. Given the complexity and severity of this disease, there is an ongoing need for evaluation of relapsing TTP and best strategies for long-term management. Disclosures Kessler: Octapharma: Consultancy, Research Funding; Novo Nordisk: Consultancy, Research Funding; Grifols: Consultancy; Genentech: Consultancy, Research Funding; Biogen: Consultancy; Pfizer: Consultancy; Bayer: Consultancy, Research Funding; Baxalta: Consultancy, Research Funding; LFB: Other: Member of DSMB. Broome:True North Therapeutics: Honoraria; Alexion Pharmaceuricals: Honoraria.

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