Thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura: 100 years of research on Moschcowitz syndrome

ABSTRACT

In the 100 years since Eli Moschcowitz reported the first case of thrombotic thrombocytopenic purpura (TTP), there has been remarkable awareness and progress in the diagnosis and management of this rare blood disorder. This progress initially was the result of careful clinical observations followed by well thought-out therapeutic interventions, with dual goals of both improving outcomes and discerning the pathophysiology of TTP. The discovery of the ADAMTS13 protease set in motion the efforts to more accurately define the specific etiologies of thrombotic microangiopathies (TMAs) based on objective, scientific data rather than clinical characterizations alone. This accurate differentiation led to better and more revealing clinical trials and advancements in the treatment of TTP and other TMAs. Further advances followed and included improvements in immune-suppressive therapy and targeted therapies of immune-mediated TTP (iTTP; caplacizumab) and congenital TTP (cTTP; recombinant ADAMTS13). The longitudinal study of patients with TTP revealed the unexpected risk for long-term complications in both patients with iTTP and those with cTTP in remission. Ongoing studies aim to further understand the prevalence, mechanisms, and appropriate screening for these mood disorders, neurocognitive deficits, and cardiovascular complications that develop at remarkably high rates and are associated with a decreased life expectancy. These discoveries are a result of the collaborative efforts of investigators worldwide that have been fostered by the frequent interactions of investigators via the International TTP Working Group meetings and TMA workshops held regularly at international meetings. These efforts will support the rapid pace of discovery and improved understanding of this rare disease.

Efficacy and safety of daratumumab in multiresistant immune-mediated thrombotic thrombocytopenic purpura

The immunosuppressive treatment of immune-mediated thrombotic thrombocytopenic purpura (iTTP) in patients with intolerance or refractoriness to the B-cell depleting monoclonal antibody rituximab remains debated. Daratumumab, a plasma cell-directed monoclonal antibody targeting CD38, represents a therapeutic option, but data are scarce. The French Thrombotic Microangiopathies Reference Center conducted a nationwide survey on iTTP patients treated with daratumumab. Nine episodes from seven patients were identified. Treatment was administered for A Disintegrin And Metalloproteinase with ThromboSpondin-1 motifs, 13th member (ADAMTS13) relapses while patients were otherwise in clinical response (N = 8), or during the acute phase of the disease following rituximab intolerance (N = 1). Patients have received a median of three previous therapeutic lines. ADAMTS13 activity improved in eight cases following daratumumab administration, including three cases where ADAMTS13 normalized. ADAMTS13 relapses occurred in three patients; in two cases, retreatment with daratumumab was successful. Median ADAMTS13 relapse-free survival was not reached; 12-month ADAMTS13 relapse-free survival was 56%. Daratumumab-related adverse events occurred in five cases and were non-severe infusion-related reactions in all cases. These results suggest that daratumumab may be an effective treatment option for iTTP patients with intolerance or refractoriness to rituximab.

Identification of HLA alleles involved in immune thrombotic thrombocytopenic purpura patients from Turkey

Thrombotic thrombocytopenic purpura (TTP) is one of the rare group disorders classified as thrombotic microangiopathies (TMAs). Approximately 90% of TTP developed immune-mediation by the formation of antibodies against the enzyme ADAMTS-13. The exact cause is unknown. To establish an association between human leukocyte antigen (HLA) and autoimmune basis, as susceptibility or protection against the disease, we contributed a study aiming to evaluate the role of HLA in immune-mediated TTP (iTTP). Considering epidemiological factors such as age, sex, ethnicity, and geographical origins, we contributed the study in our country, Turkey, which consist of a very heterogeneous population. Patients' data collection was retrospectively from electronic database on two University hospitals having big therapeutic apheresis service. Control arm was healthy people registered as stem cell donors matched in terms of age and sex. The frequency of HLA-DRB1 and HLA-DQB1 alleles between acquired TTP and the control group was compared using the chi-square method. Yates correction and logistic regression were performed on these results. A total of 75 iTTP patients and 150 healthy individuals enrolled to the study. HLA-DRB1∗11, HLA-DQB1∗03, HLA-DRB1∗11:01, HLA-DRB1∗14:01, HLA-DRB1∗13:05, HLA-DRB1∗11 + HLA-DQB1∗03 allele pair and HLA-DRB1∗15 + HLA- DQB1∗06 were proved to be susceptibility allele pairs for iTTP. HLA-DRB1∗15, HLA-DRB1∗01:01, HLA-DRB1∗07:01, HLA-DRB1∗13:01, HLA-DRB1∗14:54, HLA-DQB1∗05:01, HLA-DQB1∗02:02 and HLA-DRB1∗07 + HLA-DQB1∗02 allele pair were found to be protective against iTTP. Our findings support an association with iTTP across very heterogenous populations in Turkey.

Clinical, biological, prognostic characteristics of patients with immune-mediated thrombotic thrombocytopenic purpura and Sjögren's disease

OBJECTIVES

The association between immune-mediated thrombotic thrombocytopenic purpura (iTTP) and Sjögren disease (SjD) has been poorly investigated. This study presents the first retrospective cohort of iTTP-SjD aiming to identify risk factors for iTTP occurrence in SjD patients and examine their clinical course.

METHODS

Patients with iTTP-SjD were identified within the French TTP Registry based on American College of Rheumatology/European League Against Rheumatism 2016 criteria. A comparative analysis was conducted with two control groups comprising primary SjD (pSjD) patients from the French ASSESS cohort and idiopathic iTTP patients from the French TTP Registry. Demographic, clinical and biological data were retrospectively collected.

RESULTS

Thirty iTTP-SjD patients were included and compared with 65 pSjD and 45 idiopathic iTTP patients. The majority of iTTP-SjD patients (n=18) were diagnosed with SjD at the time of iTTP diagnosis. In comparison with the pSjD cohort, iTTP-SjD patients were diagnosed with SjD at a younger age (p=0.039) and showed a higher prevalence of anti-SjS-related antigen A antibody positivity and xerostomia (p=0.015, p=0.035, respectively). EULAR Sjogren's Syndrome Disease Activity Index showed similar activity levels between the two groups. iTTP-SjD patients were treated with plasma exchange (n=28), corticosteroids, rituximab (n=19) and caplacizumab (n=3). In comparison with the idiopathic iTTP cohort, mortality rates (log-rank tests, p=0.228), biological and clinical iTTP relapses (multivariate analysis, p=0.181) were comparable and short-term outcomes (survival at day 30, relapse) were favourable.

CONCLUSION

iTTP can be a rare complication in patients with SjD. Further studies involving larger cohorts and long-term follow-up are warranted to confirm these findings and to explore the efficacy of immunomodulators and caplacizumab in iTTP-SjD patients.

Global prevalence of hereditary thrombotic thrombocytopenic purpura determined by genetic analysis

ABSTRACT

Hereditary thrombotic thrombocytopenic purpura (hTTP) is a rare autosomal recessive, life-threatening disorder caused by a severe deficiency of the plasma enzyme, ADAMTS13. The current estimated prevalence of hTTP in different regions of the world, 0.5 to 2.0 patients per million, is determined by the frequency of diagnosed patients. To evaluate more accurately the worldwide prevalence of hTTP, and also the prevalence within distinct ethnic groups, we used data available in exome and genome sequencing of 807 162 (730 947 exomes, 76 215 genomes) subjects reported recently by the Genome Aggregation Database (gnomAD-v4.1). Among 1 614 324 analyzed alleles in the gnomAD population we identified 6321 distinct ADAMTS13 variants. Of these, 758 were defined as pathogenic; 140 (18%) variants had been previously reported and 618 (82%) were novel (predicted as pathogenic). In total 10 154 alleles (0.6%) were carrying the reported or predicted pathogenic variants; 7759 (77%) with previously reported variants. Considering all 758 pathogenic variants and also only the 140 previously reported variants, we estimated a global hTTP prevalence of 40 and 23 cases per 106, respectively. Considering only the 140 previously reported variants, the highest estimated prevalence was in East Asians (42 per 106). The estimated prevalences of other populations were: Finnish, 32 per 106; non-Finnish Europeans, 28 per 106; Admixed Americans, 19 per 106; Africans/African Americans, 6 per 106; and South Asians, 4 per 106. The lowest prevalences were Middle Eastern, 1 per 106 and Ashkenazi Jews, 0.7 per 106. This population-based genetic epidemiology study reports that hTTP prevalence is substantially higher than the currently estimated prevalence based on diagnosed patients. Many patients with hTTP may not be diagnosed or may have died during the neonatal period.

Caplacizumab as an add-on therapy in a 7-year-old girl with exacerbated immune-mediated thrombotic thrombocytopenic purpura, a case report and literature review

The cornerstone treatment for immune-mediated thrombotic thrombocytopenic purpura (iTTP) in children is a combination of therapeutic plasma exchange (TPE), corticosteroids, and rituximab. Caplacizumab is an anti-von Willebrand factor (VWF) NANOBODY molecule approved as a frontline therapy of iTTP for adults and children aged ≥12 years. Using caplacizumab in children aged <12 years remains a gray area based on recommendations but with no marketing authorization. We report the first case of a pediatric patient with iTTP successfully treated with a caplacizumab dose adjustment of 5 mg daily based on ADAMTS13 activity. We also review all published cases of iTTP in children aged <12 years treated with caplacizumab. This is a 7-year-old girl with clinical thrombotic microangiopathy, in the absence of diarrhea and kidney injury. With a French score of 2 and a PLASMIC score of 7 (high risk), the diagnosis of TTP was suspected and later confirmed by severely low ADAMTS13 activity (<5%). Immune-mediated TTP was distinguished from the congenital one due to the presence of a functional ADAMTS13 inhibitor. Daily TPE and intravenous corticosteroids were started on day 0 (D0). Rituximab was added on D4, and due to refractoriness under daily TPE, we considered off-label administration of caplacizumab from D12. A clinical answer, with a significant increase in the platelet count, was observed within 48 h. A complete ADAMTS13 recovery was reached on D62. No major adverse events were observed during the treatment. She was discharged from the hospital over 3 months ago with a platelet count still within normal ranges. In the literature, we identified a total of four case reports describing five iTTP patients aged <12 years treated with caplacizumab, with a 100% success and tolerability rate. These published data attest to the efficacy and safety of the systematic use of caplacizumab and rituximab as frontline therapy in pediatric iTTP under 12 years of age. Therefore, prospective data are needed to support commercial authorization of caplacizumab in this subpopulation. Close monitoring of ADAMTS13 activity is particularly of interest among children to limit the number of caplacizumab injections.

Catastrophic Thrombosis: A Narrative Review

Catastrophic thrombosis is a severe condition characterized by a hypercoagulable tendency, leading to multiple thromboembolic events in different blood vessels, usually within a short timeframe. Several conditions have been associated with the development of catastrophic thrombosis, including the catastrophic antiphospholipid syndrome, thrombotic anti-platelet factor 4 immune disorders, thrombotic microangiopathies, cancers, the hyper-eosinophilic syndrome, pregnancy, infections, trauma, and drugs. Thrombotic storm represents a medical emergency whose management represents a serious challenge for physicians. Besides the prompt start of anticoagulation, a patient's prognosis depends on early recognition and possible treatment of the underlying condition. In this narrative review, we summarize the main characteristics of catastrophic thrombosis, analyzing the various conditions triggering such life-threatening complication. Finally, an algorithm with the diagnostic workup and the initial management of patients with catastrophic thrombosis is presented.

A Systematic Review of the Epidemiology and Disease Burden of Congenital and Immune-Mediated Thrombotic Thrombocytopenic Purpura

Congenital (cTTP) and immune-mediated (iTTP) thrombotic thrombocytopenic purpura are serious and rare clotting disorders resulting from a deficiency in the ADAMTS13 enzyme. A systematic review was conducted using the Ovid® MEDLINE & Embase databases to synthesize the epidemiology and burden of cTTP and iTTP worldwide (from January 1, 2010, to February 6, 2020, with an update that covered the period January 1, 2020-February 11, 2022). Outcomes of interest were incidence and prevalence of TTP, incidence of acute episodes, mortality, burden of illness (eg complications, healthcare utilization, patient-reported outcomes) and disease management. A total of 221 eligible observational studies were included. The incidence rate of acute episodes ranged from 0.19-0.35 person-years in adult patients with cTTP, and 1.81-3.93 per million persons per year for iTTP in the general population. Triggers of acute episodes were similar for cTTP and iTTP, with pregnancy and infection the most commonly observed. Exacerbation in patients with iTTP varied widely, ranging from 2.4-63.1%. All-cause mortality was observed in 0-13.4% of patients with cTTP, across studies and follow-up periods, and in 1.1% (median follow-up: 0.4 years) to 18.8% (1 year) of patients with iTTP during acute episodes. Cardiovascular, renal, and neurological disease were common complications. TTP also led to work disturbances, feelings of anxiety and depression, and general activity impairment. TTP treatment regimens used were generally reflective of current treatment guidelines. The evidence identified describes a high patient burden, highlighting the need for effective treatment regimens leading to improvements in outcomes. Considerable evidence gaps exist, particularly for disease epidemiology, patient-reported outcomes, costs of disease management, and associated healthcare resource utilization. This review may help increase disease awareness and highlights the need for additional real-world studies, particularly in geographical regions outside the United States and Western Europe.

Frontline use of rituximab may prevent ADAMTS13 inhibitor boosting during caplacizumab treatment in patients with iTTP: post hoc analysis of a phase 2/3 study in Japan

BACKGROUND

A recent Phase 2/3 study in Japanese patients showed that caplacizumab was effective in treating immune-mediated thrombotic thrombocytopenic purpura (iTTP), with a low rate of iTTP recurrence. ADAMTS13 activity is monitored weekly during caplacizumab treatment to guide discontinuation of caplacizumab and consequently avoid exacerbations or relapse. The aim of this study was to assess changes in ADAMTS13 activity/inhibitor levels during caplacizumab treatment in this patient population.

METHODS

A post hoc analysis of the Phase 2/3 study in Japanese patients was conducted. Patients ≥ 18 years old with confirmed iTTP received 10 mg of caplacizumab daily in conjunction with therapeutic plasma exchange (TPE) and immunosuppression for 30 days post-TPE. Outcomes included time to recovery of ADAMTS13 activity, ADAMTS13 activity level at treatment end, incidence of ADAMTS13 inhibitor re-elevation (ie, inhibitor boosting) during treatment, time to platelet count recovery, number of days of TPE, and safety. Outcomes according to presence of inhibitor boosting were also assessed.

RESULTS

Nineteen patients had confirmed iTTP and were included in this analysis. Median (95% confidence interval) time to recovery of ADAMTS13 activity to ≥ 10%, ≥ 20%, and ≥ 60% was 14.6 (5.9-24.8), 18.5 (5.9-31.8), and 47.5 (18.5-60.9) days, respectively. Median (range) ADAMTS13 activity level at caplacizumab treatment end was 62.0% (29.0-101.0). Nine patients had ADAMTS13 inhibitor boosting. Delayed response of ADAMTS13 activity was observed in patients with inhibitor boosting. The median time to platelet count response and median number of TPE days were shorter in patients with inhibitor boosting compared with patients without inhibitor boosting. Rituximab was administered to almost all patients with inhibitor boosting (88.9%), after completion of TPE. Patients without inhibitor boosting who were treated with rituximab received it prior to completion of TPE. Only one patient experienced a recurrence, which occurred shortly after caplacizumab discontinuation due to an adverse event.

CONCLUSIONS

In patients with iTTP, caplacizumab with TPE and immunosuppression may reduce the risk of ADAMTS13 inhibitor boosting if rituximab is administered early in the iTTP treatment period. Early administration of rituximab in addition to caplacizumab may prevent iTTP recurrence with inhibitor boosting.

TRIAL REGISTRATION

NCT04074187.

Atypical Presentations of Pediatric-acquired Thrombotic Thrombocytopenic Purpura

BACKGROUND

Immune thrombotic thrombocytopenic purpura (iTTP) in children is a rare, severe thrombotic microangiopathy. This condition is characterized by microangiopathic hemolytic anemia, severe thrombocytopenia, and organ ischemia due to reduced activity of the von Willebrand factor-cleaving protease ADAMTS13.

METHODS

A retrospective case series evaluating data collected from the medical files of 4 children diagnosed with iTTP.

RESULTS

The presented case series depicts a variety of iTTP presentations: 1 case of primary iTTP, 1 case induced by Shiga toxin, 1 associated with RAS-associated autoimmune leukoproliferative disease (RALD), and 1 initial manifestation of systemic lupus erythematosus (SLE). Notably, 2 patients recovered without undergoing plasma exchange.

CONCLUSION

Early ADAMTS13 testing in children with unexplained hemolysis or thrombocytopenia is crucial. The diverse underlying causes, including infections and autoimmune disorders, underscore the complexity of iTTP in the pediatric population. These cases highlight the necessity for personalized treatment approaches that consider each patient's unique clinical situation and potential alternatives or modifications to conventional therapeutic regimens.

Refractory Thrombotic Thrombocytopenic Purpura in a Patient With Triple X Syndrome

Clinical manifestations of triple X syndrome (karyotype 47, XXX) can include autoimmune diseases. We describe the occurrence of acquired thrombotic thrombocytopenic purpura (TTP), an autoimmune condition, refractory to plasmapheresis and rituximab in a patient with triple X syndrome who required vincristine administration for disease remission. To our knowledge, this rare coexistence is the first of its kind reported in Brazil.

Acquired immune thrombotic thrombocytopenic purpura (TTP) associated with inactivated COVID-19 vaccine CoronaVac

Corona virus disease 2019 (COVID-19) due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has affected the whole world. Acquired thrombotic thrombocytopenic purpura (TTP) has been reported after administration of mRNA- or adenoviral vector-based COVID-19 vaccines, including Ad26.COV2-S, BNT162b2, mRNA-1273, and ChAdOx1 nCov-19. However, whether inactivated vaccines, such as CoronaVac, could cause TTP and whether the symptoms in TTPs caused by inactivated vaccines are different from previously reported cases are unknown. In this study, two cases were reported. Both cases developed TTP after the second CoronaVac vaccination shot, but not the first. They demonstrated symptoms of fever, neurological abnormalities, renal dysfunction, thrombocytopenia, and hemolysis. Both patients achieved complete remission through several sessions of plasma exchanges and immune suppression. The incidence of TTP in Nanjing area was analyzed. The number of patients with TTP was 12 in 2019, 6 in 2020, 16 in 2021, and 19 in 2022. To the authors' knowledge, this report is the first report of TTP associated with inactivated COVID-19 vaccine (CoronaVac). The rarity and delayed onset may be due to the relatively milder immune response caused by the inactivated vaccines than mRNA-based ones. Timely plasma exchange is a vital treatment for CoronaVac-related TTP, similar to activated vaccine-related TTP.

Practical Considerations for the Use of the Rapid AcuStar® ADAMTS13 Activity Assay in the Diagnosis of Acute Thrombotic Thrombocytopenic Purpura (TTP)

Introduction: Conventional practice in the management of acute TTP entails empirical treatment of suspected cases whilst awaiting confirmatory ADAMTS13 deficiency testing. Rapid ADAMTS13 assays offer increased accessibility and rapid diagnostics. The new automated HemosIL AcuStar® ADAMTS13 assay has seen increasing use among UK TTP Specialist Centres alongside the traditional ELISA method to confirm severe ADAMTS13 deficiency. Methods: A multi-centre retrospective case-control study was performed to review patients demonstrating discrepant ADAMTS13 activity results measured using rapid (AcuStar®) and ELISA assays in parallel from September 2019 to December 2021. Cases were compared with a cohort of suspected TTP patients exhibiting no difference in assay results and in relation to their presenting characteristics and pre-test probability of a diagnosis of TTP. Results: Where the clinical index of suspicion for TTP was high at presentation, acute TTP was confirmed using the AcuStar® assay < 0.2 IU/dL and subsequently < 10 IU/dL by ELISA with zero incidence of discrepancy. For patients with low clinical suspicion of acute TTP, a discrepancy between the AcuStar® and ELISA assay results was observed in 2% of cases; 5-10 IU/dL in AcuStar®, confirmed as >20 IU/dL by ELISA. A concurrent cancer diagnosis or sepsis was observed in 40% of discrepant cases. Conclusions: Where acute TTP is strongly suspected, there is a good correlation between the rapid AcuStar® ADAMTS13 assay and the conventional ELISA assay. Where the clinical suspicion of acute TTP is low, caution should be exercised in the interpretation of the ADAMTS13 activity using the AcuStar® assay. Accurate interpretation requires robust ADAMTS13 testing algorithms to be incorporated into diagnostic pathways.

Diagnosis of thrombotic thrombocytopenic purpura: easy-to-use fiber optic surface plasmon resonance immunoassays for automated ADAMTS-13 antigen and conformation evaluation

BACKGROUND

Laboratory diagnosis of immune-mediated thrombotic thrombocytopenic purpura (iTTP) remains challenging when ADAMTS-13 activity ranges between 10% and 20%. To prevent misdiagnosis, open ADAMTS-13 conformation gained clinical attention as a novel biomarker, especially to diagnose acute iTTP in patients with diagnostic undecisive ADAMTS-13 activity. Plasma ADAMTS-13 conformation analysis corrects for ADAMTS-13 antigen, with both parameters being characterized in enzyme-linked immunosorbent assay (ELISA)-based reference assays requiring expert technicians.

OBJECTIVES

To design ADAMTS-13 antigen and conformation assays on automated, easy-to-use fiber optic surface plasmon resonance (FO-SPR) technology to promote assay accessibility and diagnose challenging iTTP patients.

METHODS

ADAMTS-13 antigen and conformation assays were designed on FO-SPR technology. Plasma of 20 healthy donors and 20 acute iTTP patients were quantified, and data from FO-SPR and ELISA reference assays were compared.

RESULTS

Following assay design, both antigen and conformation FO-SPR assays were optimized and characterized, presenting strong analytical sensitivity (detection limit of 0.001 μg/mL) and repeatability (interassay variation of 14.4%). Comparative analysis suggested positive correlation (Spearman r of 0.92) and good agreement between FO-SPR and ELISA assays. As expected, FO-SPR assays showed a closed or open ADAMTS-13 conformation in healthy donors and acute iTTP patients, respectively.

CONCLUSION

Both ADAMTS-13 antigen and conformation assays were transferred onto automated, easy-to-use FO-SPR technology, displaying potent analytical sensitivity and reproducibility. ADAMTS-13 antigen and conformation were determined for healthy donors and acute iTTP patients showing strong correlation with ELISA reference. Introducing FO-SPR technology in clinical context could support routine diagnosis of acute iTTP patients, notably when ADAMTS-13 activity fluctuates between 10% and 20%.

Nanobody activator improves sensitivity of the von Willebrand factor activity assay to multimer size

BACKGROUND

The activity of von Willebrand factor (VWF) in facilitating platelet adhesion and aggregation correlates with its multimer size. Traditional ristocetin-dependent functional assays lack sensitivity to multimer sizes. Recently, nanobodies targeting the autoinhibitory module and activating VWF were identified.

OBJECTIVES

To develop an assay that can differentiate the platelet-binding activity of VWF multimers.

METHODS

A novel enzyme-linked immunosorbent assay (nanobody-triggered glycoprotein Ib binding assay [VWF:GPIbNab]) utilizing a VWF-activating nanobody was developed. Recombinant VWF, plasma-derived VWF (pdVWF), and selected gel-filtrated fractions of pdVWF were evaluated for VWF antigen and activity levels. A linear regression model was developed to estimate the specific activity of VWF multimers.

RESULTS

Of the 3 activating nanobodies tested, 6C11 with the lowest activation effect exhibited the highest sensitivity for high-molecular-weight multimers (HMWMs) of VWF. VWF:GPIbNab utilizing 6C11 (VWF:GPIbNab6C11) produced significantly higher activity/antigen ratios for recombinant VWF (>2.0) and HMWM-enriched pdVWF fractions (>2.0) than for pdVWF (∼1.0) or fractions enriched with shorter multimers (<1.0). The differences were much larger than those produced by VWF:GPIbNab utilizing other nanobodies, VWF:GPIbM, VWF:GPIbR, or VWF:CB assays. Linear regression analysis of 5 pdVWF fractions of various multimer sizes produced an estimated specific activity of 2.7 for HMWMs. The analysis attributed >90% of the VWF activity measured by VWF:GPIbNab6C11 to that of HMWMs, which is significantly higher than all other activity assays tested.

CONCLUSION

The VWF:GPIbNab6C11 assay exhibits higher sensitivity to HMWMs than ristocetin-based and collagen-binding assays. Future studies examining the application of this assay in clinical settings and any associated therapeutic benefit of doing so are warranted.

Comprehensive approaches to preclinical evaluation of monoclonal antibodies and their next-generation derivatives

Biotherapeutics hold great promise for the treatment of several diseases and offer innovative possibilities for new treatments that target previously unaddressed medical needs. Despite successful transitions from preclinical to clinical stages and regulatory approval, there are instances where adverse reactions arise, resulting in product withdrawals. As a result, it is essential to conduct thorough evaluations of safety and effectiveness on an individual basis. This article explores current practices, challenges, and future approaches in conducting comprehensive preclinical assessments to ensure the safety and efficacy of biotherapeutics including monoclonal antibodies, toxin-conjugates, bispecific antibodies, single-chain antibodies, Fc-engineered antibodies, antibody mimetics, and siRNA-antibody/peptide conjugates.

Small Bowel Ischemia and Ischemic Colitis Secondary to Thrombotic Thrombocytopenic Purpura in a Patient With Systemic Lupus Erythematous: A Rare Clinical Entity

Thrombotic thrombocytopenic purpura (TTP) is a rare, life-threatening hematologic disorder characterized by microangiopathic hemolytic anemia, thrombocytopenia, and organ dysfunction. This report highlights a rare case of small bowel ischemia and ischemic colitis caused by TTP in a 35-year-old woman with systemic lupus erythematosus (SLE), hypertension, and end-stage renal disease on hemodialysis. She presented with severe abdominal pain, diarrhea, vomiting, and bloody bowel movements. Diagnosed through CT, EGD, and colonoscopy and confirmed by ADAMTS13 levels, she was treated with plasma exchange, steroids, and rituximab. After standard therapies failed, resection anastomosis surgery led to clinical improvement. This case underscores the importance of early recognition and treatment of TTP in SLE patients to improve prognosis and reduce morbidity and mortality.

Clinical features, treatment, and outcomes of patients with carfilzomib induced thrombotic microangiopathy

BACKGROUND

Thrombotic microangiopathy (TMA) is associated with carfilzomib, and knowledge of carfilzomib-induced TMA is based mainly on case reports. This study investigated the clinical characteristics of patients with carfilzomib-induced TMA and provided a reference for the rational use of carfilzomib.

METHODS

Reports of carfilzomib-induced TMA were collected for retrospective analysis by searching the Chinese and English databases from inception to January 31, 2024.

RESULTS

Sixty-six patients were included, with a median age of 63 years (range 39, 85). The median time to onset of TMA was 42 days (range 1, 1825) from initial administration, and the median number of cycles was 3 cycles (range 1, 15). Hemolytic anemia was recorded in 64 patients, with a median of 8.3 g/dL (range 4.6, 13). Sixty-three patients had thrombocytopenia with a median of 18 × 109/L (range 1, 139). The median value of increased LDH was 1192 IU/L (range 141, 5378). ADAMTS13 activity was normal in 41 (62.1 %) of the 42 patients. Mutations were found in 9 (13.6 %) of the 15 patients. Fifty-seven patients achieved a clinical response after discontinuing carfilzomib and receiving therapeutic plasma exchange (53.0 %), eculizumab (24.2 %), or hemodialysis (39.4 %).

CONCLUSION

Carfilzomib-induced TMA is an important adverse event that should be considered in patients receiving carfilzomib for multiple myeloma with anemia, thrombocytopenia, and acute kidney injury. Withdrawal of carfilzomib and treatment with eculizumab have proven successful in some patients.

Detection of novel duplication variant in ADAMTS13 gene using chromosomal microarray analysis

We present a case of a child with congenital thrombotic thrombocytopenic purpura found to have a compound heterozygous variant in the ADAMTS13 gene with a novel variant resulting in a large duplication of exons 9-11 of ADAMTS13 This variant was identified through additional molecular testing via a chromosomal microarray analysis. To our knowledge, this assay had not previously been utilised to identify an ADAMTS13 variant and the additional testing was possible through the involvement of a genetic counsellor.

Thrombotic microangiopathy following a white-lipped pit viper envenomation

Certain snake envenomation patients with consumptive coagulopathy, termed venom-induced consumption coagulopathy, develop thrombotic microangiopathy (TMA). Due to predominant renal involvement, TMA is said to resemble haemolytic uraemic syndrome and is treated with haemodialysis. We present a case of a young male who presented to the emergency department after being bitten by a white-lipped pit viper (Trimeresurus albolabris). He developed heart failure in addition to acute kidney injury secondary to TMA. He was treated with 30 vials of anti-snake venom according to national guidelines and underwent haemodialysis. Despite haemodialysis, the patient's ventilatory parameters continued to worsen, necessitating invasive mechanical ventilation. Thus, he was initiated on plasma exchange therapy, to which the patient responded well. TMA has not been reported in Trimeresurus envenomations yet, to the best of our knowledge. Additionally, plasma exchange therapy can be considered an adjunctive therapy for snakebite patients who develop TMA.

Case report of thrombotic thrombocytopenic purpura during pregnancy with a review of the relevant research

RATIONALE

Thrombotic thrombocytopenic purpura (TTP) is a syndrome characterized by widespread blood vessel clotting and bleeding. It can affect individuals of any age but is more commonly observed in females, particularly during pregnancy. Pregnancy combined with TTP is a critical and rapidly progressing condition that is often misdiagnosed as an obstetric disorder like severe preeclampsia or HELLP syndrome. To deepen the understanding of TTP during pregnancy with the help of a clinical case.

PATIENT CONCERNS

A 20-year-old patient, is pregnancy 1 birth 0, 32 weeks dated by her last menstrual period, presented chest tightness, and shortness of breath after physical activity for 3 days.

DIAGNOSES

TTP.

INTERVENTIONS

At present, there are no preventive measures. Timely diagnosis and treatment are useful. Plasma exchange and treat to the patient hinder autoantibodies, such as gamma globulin, methylprednisolone, rituximab, and cyclosporine were effective.

OUTCOMES

The patient exhibited stable vital signs, normal examination results, and experienced no complications. We continued to monitor her progress after she was discharged.

LESSONS SUBSECTIONS

The acute onset of TTP is often associated with pregnancy, as it is a triggering factor. Timely identification, accurate diagnosis, and a comprehensive treatment approach involving plasma exchange, immunosuppressants, and the termination of pregnancy can lead to remission and a favorable outlook for the majority of patients.

Cost-effectiveness of rapid vs in-house vs send-out ADAMTS13 testing for immune thrombotic thrombocytopenic purpura

ABSTRACT

While awaiting confirmatory results, empiric therapy for patients suspected to have immune thrombotic thrombocytopenic purpura (iTTP) provides benefits and also accrues risks and costs. Rapid assays for ADAMTS13 may be able to avoid the cost and risk exposure associated with empiric treatment. We conducted, to our knowledge, the first cost-effectiveness evaluation of testing strategies with rapid vs traditional ADAMTS13 assays in patients with intermediate- to high-risk PLASMIC scores, with and without caplacizumab use. We built a Markov cohort simulation with 4 clinical base-case analyses: (1) intermediate-risk PLASMIC score with caplacizumab; (2) intermediate-risk PLASMIC score without caplacizumab; (3) high-risk PLASMIC score with caplacizumab; and (4) high-risk PLASMIC score without caplacizumab. Each of these evaluated 3 testing strategies: (1) rapid assay (<1-hour turnaround); (2) in-house fluorescence resonance energy transfer (FRET)-based assay (24-hour turnaround); and (3) send-out FRET-based assay (72-hour turnaround). The primary outcome was the incremental net monetary benefit reported over a 3-day time horizon and across accepted willingness-to-pay thresholds in US dollars per quality-adjusted life-year (QALY). While accruing the same amount of QALYs, the rapid assay strategy saved up to $46 820 (95% CI, $41 961-$52 486) per patient tested. No parameter variation changed the outcome. In probabilistic sensitivity analyses, the rapid assay strategy was favored in 100% (3 base cases and scenario analyses) and 99% (1 base-case and scenario analysis) across 100 000 Monte Carlo iterations within each. Rapid ADAMTS13 testing for patients with intermediate- or high-risk PLASMIC scores yields significant per patient cost savings, achieved by reducing the costs associated with unnecessary therapeutic plasma exchange and caplacizumab therapy in patients without iTTP.

Successful management of refractory immune-mediated thrombotic thrombocytopenic purpura during pregnancy and delivery using the anti-VWF nanobody caplacizumab

Pregnancy is a potential trigger of acute thrombotic thrombocytopenic purpura (TTP). The management of pregnancy-associated immune-mediated TTP (iTTP) can be challenging, especially when it is refractory to standard treatment. Caplacizumab, a nanobody to von Willebrand factor (VWF) blocking its A1 domain, is a valuable new therapeutic option. Its use is, however, not approved during pregnancy and breastfeeding. We describe the successful off-label administration of caplacizumab during pregnancy and delivery in a patient with refractory iTTP. The favourable outcome without significant thrombotic or haemorrhagic complications indicates that caplacizumab may be an effective and safe treatment option in refractory iTTP during pregnancy.

Hematological Complications of Human Immunodeficiency Virus (HIV) Infection: An Update From an HIV-Endemic Setting

Medical professionals, particularly in regions with a high burden of human immunodeficiency virus (HIV), should be alert to the hematological complications of HIV, which may include cytopenias, malignancy, and coagulation disturbances. Patients may present with these conditions as the first manifestation of HIV infection. Hematological abnormalities are often multifactorial with opportunistic infections, drugs, malignancy, and HIV infection itself contributing to the clinical presentation, and the diagnosis should consider all these factors. Life-threatening hematological complications requiring urgent diagnosis and management include thrombotic thrombocytopenic purpura, superior mediastinal syndrome, spinal cord compression, and tumor lysis syndrome due to aggressive lymphoma. Antiretroviral therapy is the therapeutic backbone, including for patients with advanced HIV, in addition to specific therapy for the complication. This article reviews the impact of HIV on the hematological system and provides a clinical and diagnostic approach, including the role of a bone marrow biopsy, focusing on perspectives from sub-Saharan Africa.

Adult-onset Still's disease with concurrent thrombotic microangiopathy: Observations from pooled analysis for an uncommon finding

BACKGROUND

Adult-onset Still's disease (AOSD) is a rare systemic inflammatory disorder that is characterized by quotidian fevers, arthritis, and an evanescent rash. Occurrence of concurrent thrombotic microangiopathy (TMA) in AOSD is rare. The treatment aspects of TMA in AOSD are actively being debated.

METHODS

Medline search using MeSH terms and snowballing yielded a total of 29 articles with co-occurrence of AOSD and thrombotic thrombocytopenic purpura (TTP) including our own. Pooled data were synthesized for descriptive analysis.

RESULTS

Median age was 35 years with a majority of females (68.96%). A majority of these studies/patients were either Asian (34.48%) or Caucasian (31.03%). Concurrent TMA at the time of AOSD diagnosis was seen in 65.51% patients. Only 3/29 patients had ADAMTS13 level less than 10%, consistent with TTP and 3/29 were diagnosed with hemolytic uremic syndrome (HUS). The remainder were diagnosed clinically. Complication rate was high, and 15/29 (51.72%) patients died or had permanent neurological/renal/vision/gangrenous complications. Median and mean ferritin peak was observed to be higher (7458 and 12 349, respectively) in patients who either died/had partial remission, compared to those who had complete response (3257 and 10 899, respectively), p = .829.

CONCLUSIONS

A majority of patients with AOSD-associated TMA either died or had permanent complications. TMA was diagnosed alongside AOSD in 65% patients, while the rest developed TMA during the course of their disease. Blurred vision may precede TMA and could help risk-stratify high-risk AOSD patients clinically. Glycosylated ferritin remains low several weeks to months after disease remission and may be used to monitor severity of disease process. Further studies are necessary to confirm the existing vascular endothelial growth factor hypothesis in AOSD-associated TMA.

Uncommon Manifestation: Thrombotic Thrombocytopenic Purpura Presenting Solely as Petechial Rash

Thrombotic thrombocytopenic purpura (TTP) is a rare, life-threatening disorder typically presenting with a classic pentad of symptoms: thrombocytopenia, microangiopathic hemolytic anemia, neurological abnormalities, renal dysfunction, and fever. This report explores an unusual presentation of TTP in a 47-year-old female with a medical history of hypertension, hyperlipidemia, and chronic TTP, who exhibited only petechial rashes, generalized weakness, and headache. Notably, the petechial rash, a less common manifestation of TTP, became a pivotal clue for the diagnosis, underscoring the necessity for vigilance even when classic symptoms are absent. This case reinforces the imperative of a high suspicion index for TTP, especially in patients with thrombocytopenia and hemolytic anemia, irrespective of other traditional signs. Plasmapheresis remains the treatment cornerstone, removing autoantibodies and replenishing ADAMTS13, as evidenced by the patient's initial response. The administration of rituximab, targeting B cells to mitigate autoantibody production against ADAMTS13, featured prominently in her management, aligning with its recognized role in refractory or relapsing TTP cases. Despite an encouraging response to rituximab, a subsequent decline in platelet count indicated the unpredictable nature of TTP and the necessity for multi-pronged therapeutic strategies. The patient's medical background and persistently low ADAMTS13 levels hinted at a chronic relapsing trajectory associated with increased morbidity and mortality. This necessitates ongoing vigilance and treatment flexibility. Highlighting this atypical TTP presentation, the report calls for immediate, robust intervention, serving as a critical reminder of the heterogeneity of TTP manifestations and the complexities in its management, thereby contributing to broader clinical awareness and improved patient prognoses.

Real-World Data Analysis of Patients Affected by Immune-Mediated Thrombotic Thrombocytopenic Purpura in Italy

Background: The therapeutic management of immune-mediated thrombotic thrombocytopenic purpura (iTTP) has recently benefited from the introduction of caplacizumab, an agent directed at the inhibition of platelet aggregation. This real-world analysis investigated the epidemiology and the demographic and clinical characteristics of iTTP patients in Italy before and after caplacizumab introduction in 2020. Methods: Hospitalized adults with iTTP were included using the administrative databases of healthcare entities covering 17 million residents. Epidemiological estimates of iTTP considered the 3-year period before and after caplacizumab introduction. After stratification by treatment with or without caplacizumab, iTTP patients were characterized for their baseline features. Results: The annual incidence before and after 2020 was estimated in the range of 4.3-5.8 cases/million and 3.6-4.6 cases/million, respectively. From 2018 to 2022, 393 patients with iTTP were included, and 42 of them were treated with caplacizumab. Caplacizumab-treated patients showed better clinical outcomes, with tendentially shorter hospital stays and lower mortality rates (no treated patients died at either 1 month or 3 months after caplacizumab treatment initiation, compared to 10.5% and 11.1% mortality rates at 1 and 3 months, respectively, of the untreated ones). Conclusions: These findings may suggest that caplacizumab advent provided clinical and survival benefits for patients with iTTP.

Pregnancy as a susceptible state for thrombotic microangiopathies

Pregnancy and the postpartum period represent phases of heightened vulnerability to thrombotic microangiopathies (TMAs), as evidenced by distinct patterns of pregnancy-specific TMAs (e.g., preeclampsia, HELLP syndrome), as well as a higher incidence of nonspecific TMAs, such as thrombotic thrombocytopenic purpura or hemolytic uremic syndrome, during pregnancy. Significant strides have been taken in understanding the underlying mechanisms of these disorders in the past 40 years. This progress has involved the identification of pivotal factors contributing to TMAs, such as the complement system, ADAMTS13, and the soluble VEGF receptor Flt1. Regardless of the specific causal factor (which is not generally unique in relation to the usual multifactorial origin of TMAs), the endothelial cell stands as a central player in the pathophysiology of TMAs. Pregnancy has a major impact on the physiology of the endothelium. Besides to the development of placenta and its vascular consequences, pregnancy modifies the characteristics of the women's microvascular endothelium and tends to render it more prone to thrombosis. This review aims to delineate the distinct features of pregnancy-related TMAs and explore the contributing mechanisms that lead to this increased susceptibility, particularly influenced by the "gravid endothelium." Furthermore, we will discuss the potential contribution of histopathological studies in facilitating the etiological diagnosis of pregnancy-related TMAs.

Stress-induced hyperglycemia is associated with the mortality of thrombotic thrombocytopenic purpura patients

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP) is a rare thrombotic microangiopathy with a rapid progression and high mortality rate. We aimed to explore early risk factors for mortality in patients with TTP.

METHODS

We conducted a retrospective analysis of 42 TTP patients that were admitted to our hospital between 2000 and 2021, with a median age of 49 (29-63) years. Risk factors for mortality were evaluated using multivariate logistic regression. Receiver operating characteristic curve analysis was used to determine the cut-off value of glucose for predicting mortality in patients, which was validated by comparison to a similar cohort in the published literature.

RESULTS

Elevated glucose level and reduced red blood cells (RBC) counts were risk factors for mortality in patients with TTP (glucose, odds ratio and 95% confidence interval: 2.476 [1.368-4.484]; RBC, odds ratio and 95% confidence interval: 0.095 [0.011-0.799]). The area under the curve of glucose was 0.827, and the cut-off value was 9.2 mmol/L, with a sensitivity of 75.0% and specificity of 95.8%. A total of 26 cases from the validation cohort had a sensitivity of 71.0% and a specificity of 84.0%. The change trends of the TTP-related laboratory indices differed during hospitalization.

CONCLUSION

Hyperglycemia at admission and unstable blood glucose levels during hospitalization may be potential predictors of mortality for TTP patients. The improved prognosis was associated with the recovery of platelet counts and a significant decrease in serum lactate dehydrogenase after five days of treatment.

Clinical characteristics of anti-GBM disease with thrombotic microangiopathy: a case report and literature review

The coexistence of anti-glomerular basement membrane (anti-GBM) disease with thrombotic microangiopathy (TMA) is rarely encountered, and the clinical characteristics of this phenomenon are not well known.A 76-year-old Japanese woman with a history of idiopathic pulmonary disease was diagnosed with anti-GBM disease due to rapidly progressive glomerulonephritis and a positive anti-GBM antibody test result. We treated the patient with hemodialysis, glucocorticoids, and plasmapheresis. During treatment, the patient suddenly became comatose. TMA was then diagnosed because of thrombocytopenia and microangiopathic hemolytic anemia. The activity of a disintegrin-like and metalloproteinase with thrombospondin type 1 motif 13 (ADAMTS-13) was retained at 48%. Although we continued the treatment, the patient died of respiratory failure. An autopsy revealed the cause of respiratory failure to be an acute exacerbation of interstitial pneumonia. The clinical findings of the renal specimen indicated anti-GBM disease; however, there were no lesions suggestive of TMA. A genetic test did not reveal an apparent genetic mutation of the atypical hemolytic uremic syndrome.We conducted a literature review of past case reports of anti-GBM disease with TMA. The following clinical characteristics were obtained. First, 75% of the cases were reported in Asia. Second, TMA tended to appear during the treatment course for anti-GBM disease and usually resolved within 12 weeks. Third, ADAMTS-13 activity was retained above 10% in 90% of the cases. Fourth, central nervous system manifestations occurred in more than half of the patients. Fifth, the renal outcome was very poor. Further studies are required to understand the pathophysiology of this phenomenon.

Management and follow-up of pregnancy-onset thrombotic thrombocytopenic purpura: the French experience

ABSTRACT

Pregnancy-onset thrombotic thrombocytopenic purpura (TTP) is a rare and life-threatening disease of which diagnosis and management requires experienced multidisciplinary teams. The mechanisms responsible for a deficiency in the disintegrin and metalloprotease with thrombospondin type 1 repeats, member 13 (ADAMTS13) leading to pregnancy-onset TTP may be congenital or acquired, and studying ADAMTS13 conformation could be of interest. The differential diagnosis between TTP and other pregnancy-associated thrombotic microangiopathies (TMA) is often challenging. Our retrospective multicenter study highlights the significance and the challenges associated with pregnancy-onset TTP and childbirth in terms of diagnosis, obstetric management, and follow-up aspects. Among 1174 pregnancy-onset TMA enrolled in the French Registry for TMA from 2000 to 2020, we identified 108 pregnancy-onset TTP: 52 immune-mediated TTP (iTTP, 48.1%), 27 acquired TTP of unidentified mechanism (uTTP, 25%), and 29 congenital TTP (cTTP, 26.9%). Data show that maternal outcome is good (survival rate: 95%) and fetal outcome is linked to the gestational age at the onset of the disease (survival rate: 75.5%). Three distinct entities with different natural histories emerged: pregnancy-onset iTTP appears similar to idiopathic iTTP, with an open ADAMTS13 conformation, and is marked by a relapse risk independent of subsequent pregnancies; pregnancy-onset uTTP appears to have a different pathophysiology with an unexpected open ADAMTS13 conformation and a very low relapse risk independent of subsequent pregnancies; finally, pregnancy-onset cTTP is characterized by the necessity of pregnancy as a systematic and specific trigger and a need for prophylactic plasmatherapy for subsequent pregnancies. This trial was registered at www.clinicaltrials.gov as #NCT00426686, and at the Health Authority and the French Ministry of Health (P051064/PHRC AOM05012).

Hemophagocytic lymphohistiocytosis is associated with deficiency and closed conformation of ADAMTS-13

Background

A disintegrin and metalloprotease with thrombospondin type 1 repeats, member 13 (ADAMTS-13) is the specific von Willebrand factor-cleaving protease and circulates in a closed and latent conformation due to a spacer/CUB1 domain interaction. ADAMTS-13 is allosterically activated after binding of its substrate or antibodies, inducing an open conformation. Recently, we suggested a potential role of plasmin (fibrinolysin) in hemostasis disorders reported in most patients with hemophagocytic lymphohistiocytosis (HLH), a rare and life-threatening condition related to a severe systemic inflammatory state. Most patients with HLH had a partial ADAMTS-13 deficiency, and plasmin could induce a truncation of the C-terminal part of ADAMTS-13 and thus an open conformation.

Objectives

To understand the effect of plasmin on ADAMTS-13, our study aimed to investigate ADAMTS-13 conformation in patients with HLH.

Methods

Forty-five critically ill patients with HLH were prospectively enrolled between April 2015 and December 2018. ADAMTS-13 activity was measured by fluorescent resonance energy transfer-VWF73 assay, ADAMTS-13 antigen, and conformation with our homemade 3H9-enzyme-linked immunosorbent assay and 1C4-enzyme-linked immunosorbent assay.

Results

ADAMTS-13 activity ranged from <10 to 65 IU/dL, and 41 of the 45 patients had a quantitative deficiency in ADAMTS-13 (activity <50 IU/dL). Twenty patients had a severe ADAMTS-13 deficiency (activity <20 IU/dL). ADAMTS-13 conformation was folded in all patients under normal conditions. Surprisingly, the switch of ADAMTS-13 conformation expected with the monoclonal antibody 17G2 (anti-CUB1) was disturbed in 6 patients (activity <20 IU/dL).

Conclusion

Our study reported that ADAMTS-13 conformation is closed in HLH and provides an indirect proof that plasmin is not able to massively degrade ADAMTS-13. Further studies on glycosylation and citrullination profiles of ADAMTS-13 are needed to understand their role in HLH.

Outcomes and Costs in Patients with Immune Thrombotic Thrombocytopenic Purpura Receiving Front-Line Versus Delayed Caplacizumab: A US Hospital Database Study

European real-world data indicate that front-line treatment with caplacizumab is associated with improved clinical outcomes compared with delayed caplacizumab treatment. The objective of the study was to describe the characteristics, treatment patterns, and outcomes in hospitalized patients with an immune-mediated thrombotic thrombocytopenic purpura (iTTP) episode treated with front-line versus delayed caplacizumab in the US. This retrospective cohort analysis of a US hospital database included adult patients (≥18 years) with an acute iTTP episode (a diagnosis of thrombotic microangiopathy and ≥1 therapeutic plasma exchange [TPE] procedure) from January 21, 2019, to February 28, 2021. Unadjusted baseline characteristics, treatment patterns, healthcare resource utilization, and costs were compared between patients who received front-line versus delayed (<2 vs ≥2 days after TPE initiation) caplacizumab treatment. Out of 39 patients, 16 (41.0%) received front-line and 23 (59.0%) received delayed treatment with caplacizumab. Baseline characteristics and symptoms were similar between the two groups. Patients who received front-line caplacizumab treatment had significantly fewer TPE administrations (median: 5.0 vs 12.0); and a significantly shorter hospital stay (median: 9.0 days vs 16.0 days) than patients receiving delayed caplacizumab therapy. Both of these were significantly lower in comparison of means (t-test P < .01). Median inpatient costs (inclusive of caplacizumab costs) were 54% higher in the delayed treated patients than in the front-line treated patients (median: $112 711 vs $73 318). TPE-specific cost was lower in the front-line treated cohort (median: $6 989 vs $10 917). In conclusion, front-line treatment with caplacizumab had shorter hospitalizations, lower healthcare resource utilization, and lower costs than delayed caplacizumab treatment after TPE therapy.

Longitudinal characterization of symptoms, healthcare resource utilization, and costs among people with thrombotic thrombocytopenic purpura compared with non-thrombotic thrombocytopenic purpura controls

AIMS

Thrombotic thrombocytopenic purpura (TTP) is an ultra-rare blood disorder, characterized by severe ADAMTS13 deficiency. Affected individuals present with potentially life-threatening acute events and may experience sub-acute and chronic TTP manifestations often resulting in long-term organ damage. Incremental symptom prevalence before, during, and after an acute event as well as healthcare resource utilization (HCRU) and costs during and after an acute event were compared between people with TTP and matched non-TTP controls.

METHODS

This retrospective, matched study used data from Merative MarketScan Commercial Database and Medicare Supplemental Database (from January 1, 2008, through September 30, 2021) to identify people with TTP (inpatient diagnosis for "thrombotic microangiopathy (TMA)" or "congenital TTP," and ≥1 claim for plasma exchange or infusion). People with TTP were matched (1:2) with non-TTP controls on age, sex, geographic region, index year, and select Elixhauser comorbidities.

RESULTS

255 people with TTP were matched with 510 non-TTP controls. Both cohorts had a mean age of 43.9 years; 71% were female. Overall, more people with TTP reported symptoms compared with non-TTP controls prior to (51% vs 43%), during (99% vs 52%), and after an acute event (85% vs 50%; p < 0.05 for all periods). Symptom prevalence decreased following an acute event compared with during an acute event, but remained high-85% of people with TTP experienced symptoms compared with 50% of non-TTP controls. HCRU and mean costs per patient per month were significantly higher in all care settings among people with TTP compared with non-TTP controls (p < 0.05).

LIMITATIONS

Identification of patient populations may have been limited due to coding errors, as the data were obtained from an administrative claims database.

CONCLUSIONS

TTP is associated with a substantial symptom burden and increased costs and HCRU during and up to almost a year after acute events, demonstrating the longitudinal burden of this disease.

Rare Immune-Related Adverse Events (irAEs): Approach to Diagnosis and Management

Immune checkpoint inhibitors (ICIs) have revolutionised the treatment landscape across many solid organ malignancies and form part of routine clinical practice in many tumours. As indications for monotherapy, doublet therapy and combination approaches with chemotherapy and targeted agents expand, clinicians must be aware of the wide range of possible immune-related adverse events (irAEs). Common toxicities, including rash, colitis, hepatitis and pneumonitis are well described in the literature, and have established diagnostic and management algorithms. Rarer toxicities, often with an incidence of less than 1%, are less defined. These syndromes can be poorly recognised, may take on a fulminant course and do not have established or evidence-based diagnostic and management strategies. As such, patients may experience increased morbidity, mortality and poorer outcomes, related both to these irAEs as well as how the treatment of these may affect the management of their underlying malignancy. In this review, we aim to explore the incidence, potential biomarkers, pathogenesis, diagnostic work-up and clinical sequelae of a selection of uncommon irAEs, with a focus on myocarditis, neurological and haematologic syndromes. Further prospective research is required to accurately define the incidence and pathogenesis of these conditions, with the aim of increasing clinician awareness of rare irAEs and to assist with a more personalised and mechanism-based approach to these syndromes.

Outcomes of thrombotic thrombocytopenic purpura patients submitted to therapeutic plasma exchange in a single center in Brazil

INTRODUCTION

Immune thrombotic thrombocytopenic purpura (iTTP) is characterized by acute systemic microvascular thrombosis and is associated with a high morbidity and mortality, especially in delayed diagnosis (later than 6-7 days from symptoms). iTTP data in Brazil is scarce, so we aimed to characterize the clinical presentation and identify predictors of death risk in patients with this disease in Brazil.

METHODS

In this single-center retrospective study the patients who underwent therapeutic plasma exchange (TPE) for presumptive or confirmed iTTP were evaluated regarding the epidemiological, clinical, laboratorial characteristics and management.

RESULTS

A total of 50 patients (90 % female), with median age (IQR) of 34.1 (27-47) years, were enrolled, of which 12 (24 %) died. The most frequent symptoms were neurological (96 %), bleeding (76 %), gastrointestinal (52 %), fever (38 %), and cardiovascular (22 %). Neurological focal deficit and cardiovascular symptoms were more frequently observed in the non-survivor group (P = 0.0019 and P = 0.007, respectively). The mean ± SD number of days from beginning of symptoms to first TPE was 12.22 ± 7.91. We identified an association regarding mortality rate with a score MITS ≥ 2 points (P = 0.04), a higher indirect bilirubin (P = 0.0006), a higher number of transfused red blood cell units (P = 0.025), and platelet transfusion (P = 0.027).

CONCLUSION

Delayed diagnosis appears to be associated with a higher frequency of neurological symptoms and mortality. Intensity of hemolysis and signs of organ ischemia, such as cardiovascular symptoms and focal neurological deficit, are indicators of death risk.

Thrombotic thrombocytopenic purpura presenting as stroke mimics with normal diffusion-weighted MRI

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP) is a rare and fatal thrombotic microangiopathy-based hematologic disease. Stroke has been reported as atypical neurological manifestations of TTP in some cases.

CASE PRESENTATION

A 65-year-old male presented with typical acute ischemic stroke symptoms including sudden-onset dysarthria, right-sided facial paralysis and hemiplegia. However, his CT and MRI scans were negative without showing any new ischemic lesions. He was diagnosed with TTP with severe thrombocytopenia, mild anemia, increased LDH, and low ADAMTS-13 activity. The symptoms and positive signs were rapidly resolved after administrating the plasma exchange therapy.

CONCLUSION

Clinicians should consider the possibility of TTP when a patient presents with acute stroke-like symptoms and thrombocytopenia, especially in an emergency room, either with or without new stroke lesions on the brain CT and MRI.

Medical consult: aHUS, TTP? How to distinguish and what to do

Immune thrombotic thrombocytopenic purpura (iTTP) caused by an autoantibody-mediated deficiency of ADAMTS13 and atypical hemolytic syndrome (aHUS) caused by alternative complement dysregulation are the most common primary thrombotic microangiopathies (TMAs). The evaluation of a patient with TMA is a medical emergency since it is critical to quickly distinguish iTTP and aHUS from other causes of TMA. Untreated iTTP is rapidly fatal, and delays in initiating complement inhibition in aHUS increase the risk of irreversible renal failure. An ADAMTS13 activity level of less than 10% is diagnostic of iTTP in the appropriate clinical setting. In settings where rapid-turnaround ADAMTS13 testing is not available, clinical features and clinical prediction tools are useful to identify patients who should receive emergent plasma exchange. We present an evidence-based approach to the initial (first 24 hours) diagnosis and management of iTTP and review the clinical and laboratory features that can be used to identify patients with aHUS who will benefit from early C5 blockade. We also discuss the potential use of complement blockade to improve outcomes in selected patients with secondary TMA.

Acquired Thrombotic Thrombocytopenic Purpura in the Presence of a Urinary Tract Infection: A Rare Pediatric Case

Thrombotic thrombocytopenic purpura (TTP) is a type of microangiopathic hemolytic anemia that rarely presents in the pediatric population. This life-threatening disorder manifests as severe consumptive thrombocytopenia and disseminated micro-thromboemboli, leading to organ ischemia. Here, we present a case of an acute first-time episode of acquired TTP in a 17-year-old African American female with a past medical history of obesity, recurrent urinary tract infections, and dysfunctional uterine bleeding managed with oral contraceptives. The disorder's insidious onset was only preceded by a urinary tract infection managed as an outpatient with oral cefdinir for four days before symptoms worsened. The patient was admitted to the pediatric intensive care unit with microangiopathic hemolytic anemia, severe thrombocytopenia, low von Willebrand factor-cleaving protease (ADAMTS13) activity, hypofibrinogenemia, gross hematuria, and acute kidney injury. Further workup was significant for a positive urine culture for Escherichia coli. Her hospital course was complicated by an acute ischemic stroke. The patient's TTP was managed by five sessions of plasmapheresis (PLEX), two once-weekly doses of rituximab, five doses of caplacizumab, three doses of high-dose solumedrol, and six days of high-dose prednisone. This regimen led to an overall uptrend in platelet counts toward normal and resolved her kidney injury. Currently, the patient continues to recover as an outpatient with no disability, managed with rituximab and caplacizumab as relapse prophylaxis. This case highlights the need for further investigation into the consideration of TTP as part of the differential diagnosis for pediatric patients presenting with severe thrombocytopenia and acute kidney injury in the absence of a significant medical history. Additionally, the utilization of rituximab, caplacizumab, steroids, and PLEX for TTP in the pediatric population should be further investigated.

Immune thrombotic thrombocytopenic purpura in older patients: Results from the Spanish TTP Registry (REPTT)

Immune thrombotic thrombocytopenic purpura (iTTP) is an ultra-rare disease that seldom occurs in the elderly. Few reports have studied the clinical course of iTTP in older patients. In this study, we have analysed the clinical characteristics at presentation and response to therapy in a series of 44 patients with iTTP ≥60 years at diagnosis from the Spanish TTP Registry and compared them with 209 patients with <60 years at diagnosis from the same Registry. Similar symptoms and laboratory results were described in both groups, except for a higher incidence of renal dysfunction among older patients (23% vs. 43.1%; p = 0.008). Front-line treatment in patients ≥60 years was like that administered in younger patients. Also, no evidence of a difference in clinical response and overall survival was seen in both groups. Of note, 14 and 25 patients ≥60 years received treatment with caplacizumab and rituximab, respectively, showing a favourable safety and efficacy profile, like that observed in patients <60 years.

Magnesium sulphate in patients with thrombotic thrombocytopenic purpura (MAGMAT): a randomised, double-blind, superiority trial

PURPOSE

Studies have suggested benefits from magnesium sulphate in thrombotic thrombocytopenic purpura (TTP). We aimed to measure the effects of magnesium sulphate supplementation on TTP recovery.

METHODS

In this multicenter, randomised, double-blind, controlled, superiority study, we enrolled adults with a clinical diagnosis of TTP. Patients were randomly allocated to receive magnesium sulphate (6 g intravenously followed by a continuous infusion of 6 g/24 h for 3 days) or placebo, in addition to the standard treatment. The primary outcome was the median time to platelet normalisation (defined as a platelet count ≥ 150 G/L). Efficacy and safety were assessed by intention-to-treat.

RESULTS

Overall, we enrolled 74 participants, including one who withdrew his/her consent. Seventy-three patients were further analyzed, 35 (48%) allocated to magnesium sulphate and 38 (52%) to placebo. The median time to platelet normalisation was 4 days (95% confidence interval [CI], 3-4) in the magnesium sulphate group and 4 days (95% CI 3-5) in the placebo group. The cause-specific hazard ratio of response was 0.93 (95% CI 0.58-1.48, p = 0.75). The number of patients with ≥ 1 serious adverse reactions was similar in the two groups. By day 90, four patients in the magnesium sulphate group and two patients in the placebo group had died (p = 0.42). The most frequent adverse event was low blood pressure occurring in 34% in the magnesium sulphate group and 29% in the placebo group (p = 0.80).

CONCLUSION

Among patients with TTP, the addition of magnesium sulphate to the standard of care did not result in a significant improvement in time to platelet normalisation.

Hereditary Thrombotic Thrombocytopenic Purpura

Hereditary thrombotic thrombocytopenic purpura (hTTP), also known as Upshaw-Schulman syndrome, is a rare genetic disorder caused by mutations in the ADAMTS13 gene that leads to decreased or absent production of the plasma von Willebrand factor (VWF)-cleaving metalloprotease ADAMTS13. The result is circulating ultra-large multimers of VWF that can cause microthrombi, intravascular occlusion and organ damage, especially at times of turbulent circulation. Patients with hTTP may have many overt or clinically silent manifestations, and a high index of suspicion is required for diagnosis. For the treatment of hTTP, the goal is simply replacement of ADAMTS13. The primary treatment is prophylaxis with plasma infusions or plasma-derived factor VIII products, providing sufficient ADAMTS13 to prevent acute episodes. When acute episodes occur, prophylaxis is intensified. Recombinant ADAMTS13, which is near to approval, will immediately be the most effective and also the most convenient treatment. In this review, we discuss the possible clinical manifestations of this rare disease and the relevant differential diagnoses in different age groups. An extensive discussion on prophylaxis and treatment strategies is also presented. Unique real patient cases have been added to highlight critical aspects of hTTP manifestations, diagnosis and treatment.

Cerebral venous thrombosis in patients with autoimmune disease, hematonosis or coronavirus disease 2019: Many familiar faces and some strangers

BACKGROUND

Cerebral venous thrombosis, a rare stroke, is characterized by neurological dysfunction caused by bleeding and/or infarction resulting from venous sinus thrombosis, the so-called venous stroke. Current guidelines recommend anticoagulants as first-line therapy in the treatment of venous stroke. With complicated causes of cerebral venous thrombosis, treatment is difficult, especially when combined with autoimmune diseases, blood diseases, and even COVID-19.

AIMS

This review summarizes the pathophysiological mechanisms, epidemiology, diagnosis, treatment, and clinical prognosis of cerebral venous thrombosis combined with autoimmune diseases, blood diseases, or infectious diseases such as COVID-19.

CONCLUSION

A systematic understanding of particular risk factors that should not be neglected when unconventional cerebral venous thrombosis occurs and for a scientific understanding of pathophysiological mechanisms, clinical diagnosis, and treatment, thus contributing to knowledge on special types of venous stroke.

Evaluation of two fully automated ADAMTS13 activity assays in comparison to manual FRET assay

INTRODUCTION

The objective of the present study was to evaluate and compare the validity and utility of two fully automated ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) activity assays for clinical diagnostic decision-making and to compare their performance.

METHODS

Two automated ADAMTS13 activity assays (Werfen HemosIL® AcuStar ADAMTS13 Activity, Technoclone Technofluor ADAMTS13 Activity) were compared with a manual FRET assay (BioMedica ACTIFLUOR ADAMTS13 Activity). The following samples were used: 13 acute phase TTP (thrombotic thrombocytopenic purpura) samples from 11 different patients, one sample from a patient with congenital ADAMTS13 deficiency, 16 samples from control patients, three follow-up samples from TTP patients in long-term remission and one sample from a patient with stem cell transplantation related thrombotic microangiopathy (TMA). The WHO 1st International Standard for ADAMTS13 and several dilutions of normal plasma with ADAMTS13-depleted normal plasma were also tested. Statistical analysis included descriptive statistics, sensitivity and specificity, Passing & Bablok regression and Bland-Altman plot.

RESULTS

The quantitative comparison between the HemosIL® (x) and Technofluor (y) methods showed a strong correlation (Pearson r = 0.98, n = 49). When considering an ADAMTS13 activity of <10% as a hallmark for the diagnosis of TTP, two fully automated assays were both able to identify all TTP- and non-TTP-samples correctly, resulting in sensitivities and specificities of 100%.

CONCLUSION

Both fully automated ADAMTS13 activity assays showed a good diagnostic performance and quantitative correlation among themselves, discriminating reliably between TTP- and non-TTP-patients.

An Interesting Case of Refractory Thrombotic Thrombocytopenic Purpura in the First Trimester of a Twin Pregnancy

Thrombotic thrombocytopenic purpura (TTP) is a rare pregnancy complication characterized by microangiopathic hemolytic anemia and consumption thrombocytopenia. We herein describe the case report of a 32-year-old woman who was six weeks pregnant with twins and developed thrombotic thrombocytic purpura (TTP). The patient had a history of sickle cell trait, migraines, and preeclampsia. She presented with complaints of nausea, fatigue, sore throat, and cough and was found to be anemic with a hemoglobin of 7 g/dl and thrombocytopenic with a platelet count of 8 x 103/μL. The patient was promptly initiated on steroids and plasmapheresis with an excellent initial response. However, after three days, she developed a sudden onset headache and shortness of breath, and repeat labs showed worsening anemia (7.3 g/dl) and thrombocytopenia (8 x 103/μL). ADAMTS13 activity was significantly low at 2%. Plasmapheresis was continued, and caplacizumab and rituximab treatment was initiated. The fetal ultrasound showed no cardiac activity in the fetal poles, and the patient had a dilation and curettage (D&C) for a missed abortion. She was discharged with a prednisone taper, daily caplacizumab, and weekly rituximab. This case report underscores the criticality of the prompt identification of TTP in its early stages, and appropriate management strategies for patients with refractory TTP (rTTP), including plasmapheresis, caplacizumab, and rituximab.

Hemostatic Profile and Serological Response of Patients with Immune Thrombotic Thrombocytopenic Purpura after Receiving BNT162b2 Vaccine: A Prospective Study

INTRODUCTION

 Coronavirus disease is a clinical challenge for patients with autoimmune conditions. Patients affected by immune thrombotic thrombocytopenic purpura (iTTP) are particularly vulnerable to SARS-CoV-2 infection. Protecting these patients with vaccination is therefore mandatory, although concerns may exist on a possible increased thrombotic risk or risk of disease relapse after vaccine exposure. So far, there is no information on serological response and hemostatic activation in iTTP patients after SARS-CoV-2 vaccination.

MATERIALS AND METHODS

 In this study, in April 2021, we enrolled iTTP patients in clinical remission and on regular outpatient follow-up to receive the first and second dose BNT162b2 vaccine as a part of a prospective trial aimed at monitoring for 6 months after vaccination the occurrence of subclinical laboratory signs of clotting activation, as well as overt thrombotic complications or disease relapse. The seroconversion response was monitored in parallel. The results were compared with those of control non-iTTP subjects.

RESULTS

 A moderate decrease of ADAMTS-13 activity was recorded at 3 and 6 months in five patients with normal values at baseline, while an ADAMTS-13 relapse occurred at 6 months in one patient. Abnormalities in the endothelium activation biomarkers postvaccination were observed in iTTP patients compared with controls. The immunological response to vaccine was overall positive. No clinical iTTP relapses or thrombotic events manifested in the 6 month-follow-up after vaccination.

CONCLUSION

 The results of this study are in favor of efficacy and safety of mRNA vaccines in patients with iTTP, and highlight the importance of long-term monitoring of iTTP patients.