Patients with refractory catastrophic antiphospholipid syndrome respond inconsistently to eculizumab

Pediatric antiphospholipid syndrome: expanding our understanding of antiphospholipid syndrome in children

PURPOSE OF REVIEW

Antiphospholipid syndrome (APS) is an autoimmune, thromboinflammatory disease, which affects children and adults. There are particular features of the disease and nuances to diagnosis and management in a pediatric population, which must be appreciated to improve clinical care.

RECENT FINDINGS

Pediatric-specific epidemiological studies highlight that pediatric APS is quite rare with incidence in some populations of 0.2 per 100 000. There are new classification criteria in APS, which include a wider range of clinical features increasingly identified in registry data and case series of pediatric APS, though validation in pediatric APS is still needed. There is a particularly high proportion of pediatric APS patients with noncriteria antiphospholipid antibodies (aPL). Recurrent thrombosis is especially common in pediatric APS, highlighting the difficulty of management of this disease with high morbidity in children.

SUMMARY

Recent research has enhanced understanding of pediatric-specific APS epidemiology, laboratory findings, the wide variety of clinical features, and challenges in successful treatment. Future directions could include evaluation of potentially unique features in pediatric pathophysiology, an evaluation of the new APS classification criteria in children, broader prospective data on clinical and laboratory features, and a continued search for treatment beyond committing young patients to lifelong anticoagulation.

Non-plasmapheresis Approaches for Managing Severe Renal Thrombotic Microangiopathy: A Report of 7 Cases

C5-blockers are the established treatment for complement-mediated hemolytic uremic syndrome (CM-HUS). However, CM-HUS, lacking a definitive test, prompts plasma exchanges as a common first-line therapy, pending further assessments, despite complications and limited evidence in this indication. Recent experts' opinion endorses C5-blockers as the initial treatment for severe renal thrombotic microangiopathy (TMA). This retrospective, single-center study reports a series of 7 patients treated with a plasmapheresis-free approach. All patients presented with severe renal TMA symptoms and low French score and received prompt 900mg eculizumab within a median of 9 hours from admission. Hematological recovery was rapid, and renal function improved in 6 patients within 6.5 days, with a median hospital stay of 16 days. No rescue plasmapheresis was used. We report 7 cases of an early C5-blocker and plasmapheresis-free strategy in severe renal TMA suspicious for CM-HUS, demonstrating promising initial results. Clinical trials are needed to confirm the efficacy and safety of this approach. Addressing the high cost of C5-blocking therapies and exploring cost-effective alternatives is also crucial for broader implementation and accessibility in targeted therapies for adult renal TMA.

Unresolved issues in the diagnosis and management of thrombotic antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a highly prothrombotic autoimmune disease characterized by the persistent presence of antiphospholipid autoantibodies (aPL) in association with thrombotic or nonthrombotic macro- and microvascular manifestations and/or pregnancy complications. This review is restricted to thrombotic APS. Since the publication of the American College of Rheumatology/European Alliance of Associations for Rheumatology classification criteria for APS, several authors have emphasized the difference between "classification" and "diagnosis" as a potential pitfall for clinicians. In addition to challenges associated with the diagnosis of APS, there are many unresolved areas in understanding pathogenesis and in the management of both thrombotic and obstetric APS. Although APS is an antibody-mediated autoimmune disease, secondary thrombosis prevention is achieved by anticoagulation, mainly with vitamin K antagonists, such as warfarin, rather than immunomodulation. Evidence is convincing for the use of vitamin K antagonists in triple-positive APS with venous thromboembolism. However, the best anticoagulant approach in the management of venous thromboembolism patients with single or dual positive aPL is not clear. Management of patients with stroke or arterial thrombosis with aPL remains a major unresolved issue, although some guidelines recommend the use of warfarin rather than antiplatelet therapy as the first-line treatment of stroke in APS. Recurrent thrombosis, despite therapeutic anticoagulation, remains a frequent problem and may be explained by the contribution of thrombo-inflammation in patients with thrombotic APS. In this narrative review, we discuss some of the unresolved issues in the diagnosis and management of thrombotic APS.

Catastrophic antiphospholipid syndrome: a CAPS-tivating hematologic disease

Catastrophic antiphospholipid syndrome (CAPS) is a rare but life-threatening form of antiphospholipid syndrome (APS) defined by the rapid onset of large and small vessel thrombosis occurring simultaneously across multiple sites, resulting in multiorgan dysfunction. The presence of underlying immune dysfunction causing activation of coagulation and, in many cases, abnormal complement regulation predisposes these patients to thrombotic events. CAPS is often preceded by triggering factors such as infection, surgery, trauma, anticoagulation discontinuation, and malignancy. Given the high mortality rate, which may exceed 50%, prompt recognition and initiation of management is required. The detection of antiphospholipid antibodies and the histopathologic identification of microvascular ischemia via tissue biopsy are required to diagnose CAPS. However, these patients are often too unwell to obtain results and wait for them. As such, investigations should not delay CAPS therapy, especially if there is strong clinical suspicion. Management of CAPS requires "triple therapy" with glucocorticoids, intravenous heparin, therapeutic plasma exchange, and/or intravenous immunoglobulin. Treatment for refractory disease is based on poor-quality evidence but includes anti-CD20 (rituximab) or anticomplement (eculizumab) monoclonal antibodies and other immunosuppressant agents, either alone or in combination. The rarity of this syndrome and the subsequent lack of randomized clinical trials have led to a paucity of high-quality evidence to guide management. Continued international collaboration to expand ongoing CAPS registries will allow a better understanding of the response to newer targeted therapy.

Case report: Timing of eculizumab treatment in catastrophic antiphospholipid syndrome

Catastrophic antiphospholipid syndrome (CAPS) is a life-threatening condition of small-vessel thrombosis with acute multiple-organ involvement and visceral damage. In this report, we present a case of a patient with CAPS who is refractory to conventional therapy. For the first time in a patient with CAPS, marked C5b-9 formation was demonstrated on microvascular endothelial cells, suggesting the usefulness of therapeutic complement inhibition in this setting. Eculizumab, a C5-blocking monoclonal antibody, is remarkably effective in the treatment of different forms of thrombotic microangiopathy by controlling complement system hyperactivation. It halted the "thrombotic storm" and promptly achieved full recovery of thrombocytopenia. However, kidney function did not recover, possibly because eculizumab was administered too late. Conceivably, the timing of treatment is crucial to achieving disease remission before irreversible structural damage occurs in target organs, thereby preventing their complete functional recovery.

Hematological features and alternate diagnoses in critically ill thrombotic antiphospholipid syndrome patients

OBJECTIVES

Severe thrombotic antiphospholipid syndrome (APS) frequently affects the kidney, heart, and central nervous system. The precise frequency, clinical picture, differential diagnoses, and outcome of APS-related hematological involvement are lacking, especially in patients requiring ICU admission. This study aimed to describe the hematological manifestations associated with critically ill thrombotic APS patients and catastrophic antiphospholipid syndrome.

METHODS

This French, national, multicenter, retrospective study, conducted, from January 2000 to September 2018, included all APS patients admitted to 24 participating centers' ICUs with any new thrombotic manifestation. The prevalence of hematological manifestations and their associated outcomes were studied.

RESULTS

One hundred and thirty-four patients, female 72%, median [IQR] age 45 [34-56] years, with 152 episodes were included. Anemia was present in 95% of episodes and thrombocytopenia in 93%. The lowest values for hemoglobin and platelets were 7.1 [6.3-8.8] g/dL and 38 [21-60] g/L, respectively. The lowest platelet count below 20 g/L was significantly associated with a higher in-ICU mortality rate (50%, p < 0.0001). A thrombotic microangiopathy syndrome (TMA) syndrome was seen in 16 patients (12%) and was associated with higher in-hospital mortality (p = 0.05). Median ADAMTS-13 levels were 44% [27-74]. Anti-ADAMTS13 antibodies were tested in 11 patients and found negative in all. A suspicion of heparin-induced thrombocytopenia (HIT) was raised in 66 patients but only four patients were classified as definite HIT. Disseminated intravascular coagulation (DIC) was seen in 51% of patients.

CONCLUSION

Thrombocytopenia is very frequent in severe APS patients and may be related to TMA, HIT, or DIC. Deciphering the mechanisms of thrombocytopenia is decisive in CAPS patients. Key Points • Thrombocytopenia is the hallmark laboratory finding in CAPS. • A complete thrombotic microangiopathy pattern is infrequent in CAPS patients. • Alternate diagnoses of CAPS, especially heparin-induced thrombocytopenia, need to be adequately investigated.

Antiphospholipid Patients Admitted in the Intensive Care Unit: What Must The Rheumatologist Know?

PURPOSE OF THE REVIEW

Antiphospholipid syndrome (APS) is a rare systemic autoimmune disorder that can escalate into a 'thrombotic storm' called the catastrophic antiphospholipid syndrome (CAPS), frequently requiring ICU admission for multiple organ failure. This review aims to offer insight and recent evidence on critically-ill APS patients.

RECENT FINDINGS

The CAPS classification criteria define this condition as the involvement of at least three organs/systems/tissues within less than a week, caused by small vessel thrombosis, in patients with elevated antiphospholipid antibodies levels. These criteria do not encompass the full spectrum of critically-ill thrombotic APS patients and they need to be cautiously used for the bedside diagnosis of CAPS. Thrombocytopenia is the laboratory hallmark of CAPS, sometimes dropping below 20G/L, but a complete thrombotic microangiopathy pattern is infrequent. Anticoagulation is the pivotal treatment for APS and CAPS, associated with improved outcome. Triple therapy - the combination of anticoagulation, high-dose corticosteroids, and either plasma exchange or intravenous immunoglobulins - remains the standard treatment for CAPS patients. Eculizumab, an anti-C5 monoclonal antibody, may be useful in refractory patients. Despite significant progress, CAPS mortality rate remains high. Its diagnosis and management are complex, requiring a close multidisciplinary cross talk between APS specialists and intensivists.

Rethinking antiphospholipid syndrome to guide future management and research

Antiphospholipid syndrome (APS) consists of thrombotic, non-thrombotic and obstetric clinical manifestations developing in individuals with persistent antiphospholipid antibodies (aPL). Although researchers have made progress in characterizing different clinical phenotypes of aPL-positive people, the current approach to clinical management is still mostly based on a 'one size fits all' strategy, which is derived from the results of a limited number of prospective, controlled studies. With the 2023 publication of the ACR-EULAR APS classification criteria, it is now possible to rethink APS, to lay the groundwork for subphenotyping through novel pathophysiology-informed approaches, and to set a future APS research agenda guided by unmet needs in clinical management.

Catastrophic antiphospholipid syndrome after pregnancy complicated by hemolysis, elevated liver enzymes and low platelets syndrome

Background

Antiphospholipid syndrome (APLS) is rarely complicated by catastrophic antiphospholipid syndrome (CAPS). Peripartum CAPS is rarer still and can masquerade as other obstetric disorders. A high degree of suspicion is critical for early diagnosis and specific management given the significant morbidity and mortality associated with this disorder.

Case

We report a case of a 27-year-old at 22 week's gestation with a history of APLS found to have severe hemolysis, elevated liver enzymes and low platelets (HELLP) syndrome, resulting in termination of pregnancy. Further workup revealed the diagnosis of CAPS followed by prompt treatment with triple therapy leading to clinical improvement.

Conclusion

CAPS should be considered within the differential in an obstetric patient with a history of APLS who has evidence of multiorgan involvement with macro- or microvascular thrombosis. Although this may mimic alternative disorders, prompt diagnosis is imperative for appropriate therapy and reduction in maternal morbidity and mortality.

Anticoagulant and non-anticoagulant therapy in thrombotic antiphospholipid syndrome: old drugs and new treatment targets

In this review, we discuss the current evidence on classic and newer oral anticoagulant therapy, older drugs such as HCQ and statins, and new potential treatment targets in APS. Vitamin K antagonists (VKAs) remain the cornerstone treatment for thrombotic events in APS. In patients fulfilling criteria for definite APS presenting with a first venous thrombosis, treatment with VKAs with a target international normalized ratio (INR) 2.0-3.0 is recommended. In patients with arterial thrombosis, treatment with VKA with target INR 2.0-3.0 or 3.0-4.0 is recommended by recent guidelines, considering the individual's bleeding and thrombosis recurrence risk. A combination of VKAs and low-dose aspirin (75-100 mg/daily) may also be considered. According to available evidence direct oral anticoagulants should be avoided in patients with arterial thrombosis and/or those with triple aPL positivity. Adjunctive treatment with HCQ and/or statins can be considered, especially in anticoagulation treatment-refractory APS. Potential targeted treatments in APS include B-cell targeting, complement inhibition, mammalian target of rapamycin inhibition, IFN targeting, adenosine receptors agonists, CD38 targeting or chimeric antigen receptor T-cell therapy. The safety and efficacy of these treatment targets needs to be examined in well-designed randomized controlled trials.

Complement inhibitors for kidney disease

A refined understanding of the role of complement in the pathogenesis of glomerular and other kidney diseases has, over the past two decades, been matched by the development of novel, complement-targeting therapies. As we increasingly recognize the important role that complement activation across all three pathways-classical, lectin and alternative-plays in glomerular lesions both rare (e.g. C3 glomerulopathy) and common (e.g. immunoglobulin A nephropathy), we can identify avenues for precise, targeted approaches to modifying the natural history of these kidney diseases. In this review, we survey the evidence on using complement inhibition from the earliest, small-scale studies focusing on C5-targeting agents to more recent, large, multicenter, randomized trials utilizing complement blockade higher up in the complement pathway at the level of C3. We conclude by examining where the field of complement targeting therapy may be headed in light of these studies.

Antiphospholipid syndrome nephropathy: Current knowledge and unanswered questions

The definition of acute and chronic antiphospholipid syndrome (APS) nephropathy was recently updated using a multiphase methodology in the context of the development of the new APS classification criteria. Currently, there is no consensus for the treatment of APS nephropathy, which mainly relies on the general recommendations for the management of APS. Based on evidence from experimental studies and a few clinical studies and case series, targeted treatments such as B-cell depletion, anti-B-cell activating factor antibody, complement inhibition, mammalian target of rapamycin inhibition, and neutrophil extracellular traps or interferon targeting may show promise for the treatment of microvascular manifestations in APS, including APS nephropathy. Validation of the new APS nephropathy definition and/or efforts for improvement in proposed terminology, along with the assessment of the safety and efficacy of potential targeted treatments in randomized controlled trials, are major future research directions. In this review, we summarize the current knowledge of APS nephropathy and discuss unanswered questions.

French National Diagnostic and Care Protocol for antiphospholipid syndrome in adults and children

Antiphospholipid syndrome (APS) is a chronic autoimmune disease involving vascular thrombosis and/or obstetric morbidity and persistent antibodies to phospholipids or certain phospholipid-associated proteins. It is a rare condition in adults and even rarer in children. The diagnosis of APS can be facilitated by the use of classification criteria based on a combination of clinical and biological features. APS may be rapidly progressive with multiple, often synchronous thromboses, resulting in life-threatening multiple organ failure. This form is known as "catastrophic antiphospholipid syndrome" (CAPS). It may be primary or associated with systemic lupus erythematosus (associated APS) and in very rare cases with other systemic autoimmune diseases. General practitioners and paediatricians may encounter APS in patients with one or more vascular thromboses. Because APS is so rare and difficult to diagnosis (risk of overdiagnosis) any suspected case should be confirmed rapidly and sometimes urgently by an APS specialist. First-line treatment of thrombotic events in APS includes heparin followed by long-term anticoagulation with a VKA, usually warfarin. Except in the specific case of stroke, anticoagulants should be started as early as possible. Any temporary discontinuation of anticoagulants is associated with a high risk of thrombosis in APS. A reference/competence centre specialised in autoimmune diseases must be urgently consulted for the therapeutic management of CAPS.

Antiphospholipid syndrome: advances in diagnosis, pathogenesis, and management

Antiphospholipid syndrome (APS) is a thrombo-inflammatory disease propelled by circulating autoantibodies that recognize cell surface phospholipids and phospholipid binding proteins. The result is an increased risk of thrombotic events, pregnancy morbidity, and various other autoimmune and inflammatory complications. Although antiphospholipid syndrome was first recognized in patients with lupus, the stand alone presentation of antiphospholipid syndrome is at least equally common. Overall, the diagnosis appears to affect at least one in 2000 people. Studies of antiphospholipid syndrome pathogenesis have long focused on logical candidates such as coagulation factors, endothelial cells, and platelets. Recent work has shed light on additional potential therapeutic targets within the innate immune system, including the complement system and neutrophil extracellular traps. Vitamin K antagonists remain the mainstay of treatment for most patients with thrombotic antiphospholipid syndrome and, based on current data, appear superior to the more targeted direct oral anticoagulants. The potential role of immunomodulatory treatments in antiphospholipid syndrome management is receiving increased attention. As for many systemic autoimmune diseases, the most important future direction is to more precisely identify mechanistic drivers of disease heterogeneity in pursuit of unlocking personalized and proactive treatments for patients.

Emerging Therapies in Antiphospholipid Syndrome

The antiphospholipid syndrome (APS) is the most common cause of acquired immune-mediated thrombophilia. This syndrome is broadly defined by the presence of arterial or venous thrombosis, or pregnancy morbidity, in the presence of high levels of antiphospholipid antibodies. Despite recognition of this disorder more than 50 years ago, a fundamental unifying pathogenesis has not been determined. Due to this, mechanism-based therapies for APS are not available, and current management following thrombotic events suggests anticoagulation of indeterminate duration, or for obstetric complications, heparin/low molecular weight heparin and aspirin. However, APS is an autoimmune disorder, and several approaches focused on modulating the immune response or its effectors have been employed. Those which have been most extensively studied include hydroxychloroquine, rituximab and eculizumab, an inhibitor of complement C5. In this report, we review in depth, and critique, key clinical studies of these agents. Since all of these studies are small, our conclusions are qualified. However, it appears that hydroxychloroquine may enhance the anticoagulant efficacy of vitamin K antagonists in APS patients, and that rituximab may ameliorate some of the "non-criteria" manifestations of APS. The catastrophic antiphospholipid syndrome (CAPS) is associated with diffuse thrombosis, multi-organ dysfunction, and ∼30% mortality. A high incidence of complement regulatory gene mutations, and compelling data concerning the efficacy of eculizumab in CAPS, suggests an important role for complement in this disorder. However, additional work is needed to clarify the role of complement in non-catastrophic APS, though emerging data suggests that complement inhibition may be effective in preventing thrombosis in these patients as well.

Complement and the prothrombotic state

In 2007 and 2009, the regulatory approval of the first-in-class complement inhibitor eculizumab revolutionized the clinical management of 2 rare, life-threatening clinical conditions: paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome (aHUS). Although being completely distinct diseases affecting blood cells and the glomerulus, PNH and aHUS remarkably share several features in their etiology and clinical presentation. An imbalance between complement activation and regulation at host surfaces underlies both diseases precipitating in severe thrombotic events that are largely resistant to anticoagulant and/or antiplatelet therapies. Inhibition of the common terminal complement pathway by eculizumab prevents the frequently occurring thrombotic events responsible for the high mortality and morbidity observed in patients not treated with anticomplement therapy. Although many in vitro and ex vivo studies elaborate numerous different molecular interactions between complement activation products and hemostasis, this review focuses on the clinical evidence that links these 2 fields in humans. Several noninfectious conditions with known complement involvement are scrutinized for common patterns concerning a prothrombotic statues and the occurrence of certain complement activation levels. Next to PNH and aHUS, germline-encoded CD59 or CD55 deficiency (the latter causing the disease complement hyperactivation, angiopathic thrombosis, and protein-losing enteropathy), autoimmune hemolytic anemia, (catastrophic) antiphospholipid syndrome, and C3 glomerulopathy are considered. Parallels and distinct features among these conditions are discussed against the background of thrombosis, complement activation, and potential complement diagnostic and therapeutic avenues.

Mechanisms of immunothrombosis and vasculopathy in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune thrombophilia propelled by circulating antiphospholipid antibodies that herald vascular thrombosis and obstetrical complications. Antiphospholipid antibodies recognize phospholipids and phospholipid-binding proteins and are not only markers of disease but also key drivers of APS pathophysiology. Thrombotic events in APS can be attributed to various conspirators including activated endothelial cells, platelets, and myeloid-lineage cells, as well as derangements in coagulation and fibrinolytic systems. Furthermore, recent work has especially highlighted the role of neutrophil extracellular traps (NETs) and the complement system in APS thrombosis. Beyond acute thrombosis, patients with APS can also develop an occlusive vasculopathy, a long-term consequence of APS characterized by cell proliferation and infiltration that progressively expands the intima and leads to organ damage. This review will highlight known pathogenic factors in APS and will also briefly discuss similarities between APS and the thrombophilic coagulopathy of COVID-19.

A Case Report of COVID-Associated Catastrophic Antiphospholipid Syndrome Successfully Treated with Eculizumab

Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by multiple episodes of venous and arterial thromboses or recurrent fetal losses in the presence of antiphospholipid antibodies against β₂GP1, frequently accompanied by moderate thrombocytopenia. Catastrophic APS (CAPS) is a severe manifestation of APS. COVID-19 may have an intense hypercoagulable state in critically ill patients. SARS-CoV2 may potentiate pathogenic APS effects, including the activation of endothelial cells, monocytes, platelets, and complement, resulting in a proinflammatory state and prothrombotic events. The endothelial tropism of SARS-CoV2 may also modify the clinical presentation of COVID-19 in susceptible individuals and trigger flares of underlying vascular diseases. We report a case of a 64-year-old woman with a history of triple-positive APS who had multiple thrombotic and bleeding episodes after being found to have a COVID-19 infection temporally associated with CAPS development that was successfully treated with eculizumab, preventing further macro- and microvascular thrombotic events at 1 month follow-up. Our case highlights the need for more research regarding the mechanism by which COVID-19 may potentiate APS and lead to the development of CAPS.

Markers of complement activation in plasma during quiescent phases in patients with catastrophic antiphospholipid syndrome

Accumulating evidence suggests that complement activation is a critical contributor to catastrophic antiphospholipid syndrome (CAPS). While complement activation and C5b-9 levels have been documented in acute CAPS, Ruffati et al report that patients with a history of CAPS have higher levels of C5a and C5b-9 even in the quiescent phase, suggesting an underlying defect in complement regulation.

Management of Antiphospholipid Syndrome

Antiphospholipid syndrome (APS), is an acquired autoimmune disorder characterised by thrombosis, pregnancy morbidity, and the presence of antiphospholipid antibodies (aPL). Although venous thromboembolism is the most common manifestation, thrombotic events in APS may also occur in virtually any vascular bed, with cerebral circulation being the arterial territory most commonly affected. As APS is a heterogeneous condition, its management should be tailored with a patient-centred approach based on individual risk assessment, which includes the aPL profile, concomitant auto-immune diseases, and traditional cardiovascular risk factors. Although literature data are conflicting regarding primary prophylaxis, there is some evidence indicating that antiplatelet agents may reduce the risk of a first thrombotic event in individuals with a high-risk profile. In patients with thrombotic APS, current evidence-based guidelines recommend lifelong vitamin K antagonists (VKAs), preferably warfarin. The optimal intensity of anticoagulation following arterial thrombosis remains controversial. Arterial thrombosis should be treated either with high-intensity warfarin at a target INR > 3.0, or low-dose aspirin (LDA) combined with moderate-intensity warfarin (INR 2.0-3.0). It is recommended to avoid direct oral anticoagulants (DOACs) in patients with high-risk APS, mainly those with triple-positive PL and previous arterial events. They would only be used exceptionally in selected patients with low-risk venous thromboembolism (VTE). In low-risk VTE patients currently treated with a DOAC due to warfarin intolerance or a previous unstable International Normalized Ratio on warfarin, the decision of continuing DOACs would be taken in carefully selected patients. In women with obstetric APS, the combination therapy with LDA plus heparin remains the conventional strategy.