Long-term treatment with rilzabrutinib in patients with immune thrombocytopenia

ABSTRACT

Immune thrombocytopenia (ITP) is an autoimmune disease associated with autoantibody-mediated platelet destruction and impaired platelet production, resulting in thrombocytopenia and a predisposition to bleeding. The ongoing, global phase 1/2 study showed that rilzabrutinib, a Bruton tyrosine kinase inhibitor specifically developed to treat autoimmune disorders, could be an efficacious and well-tolerated treatment for ITP. Clinical activity, durability of response, and safety were evaluated in 16 responding patients who continued rilzabrutinib 400 mg twice daily in the long-term extension (LTE) study. At LTE entry, the median platelet count was 87 × 109/L in all patients, 68 × 109/L in those who had rilzabrutinib monotherapy (n = 5), and 156 × 109/L in patients who received concomitant ITP medication (thrombopoietin-receptor agonists and/or corticosteroids, n = 11). At a median duration of treatment of 478 days (range, 303-764), 11 of 16 patients (69%) continued to receive rilzabrutinib. A platelet count of ≥50 × 109/L was reported in 93% of patients for more than half of their monthly visits. The median percentage of LTE weeks with platelet counts ≥30 × 109/L and ≥50 × 109/L was 100% and 88%, respectively. Five patients discontinued concomitant ITP therapy and maintained median platelet counts of 106 × 109/L at 3 to 6 months after stopping concomitant ITP therapy. Adverse events related to treatment were grade 1 or 2 and transient, with no bleeding, thrombotic, or serious adverse events. With continued rilzabrutinib treatment in the LTE, platelet responses were durable and stable over time with no new safety signals. This trial is registered at www.clinicaltrials.gov as #NCT03395210 and www.clinicaltrialsregister.eu as EudraCT 2017-004012-19.

Safety and efficacy of SARS-CoV-2 vaccination in patients with immune thrombocytopenia: A two-centre review

Multiple studies have reported immune thrombocytopenia (ITP) relapse following SARS-CoV-2 vaccination, however baseline ITP relapse rate and antibody response to vaccination are not known. Patients with ITP who received at least one of the first three SARS-CoV-2 vaccination doses were included in the study. One hundred and twenty-four patients met the inclusion criteria. Relapse rate was 4.2% following a first vaccine dose, 9.1% after a second and 2.9% after a third; baseline relapse rate was 7.6%. Ninety-four per cent of patients who received three vaccine doses developed a clinical antibody response. SARS-CoV-2 vaccination appears to be safe and effective in patients with ITP.

Patient preferences and experiences regarding thrombopoietin-receptor agonists for immune thrombocytopenia in The Netherlands (TRAPeze Netherlands study)

OBJECTIVE

Identify patient experience and preference towards thrombopoietin-receptor agonists (TPO-RAs) in treatment of immune thrombocytopenia (ITP) in the Netherlands.

METHODS

The Thrombopoietin-Receptor Agonist Patient experience (TRAPeze) survey used a discrete choice experiment (DCE) to elicit patient preferences and a patient burden survey (PBS) to evaluate the clinical and social impact of ITP. TRAPeze collected responses from 6th October to 19th November 2021.

RESULTS

Seventy-six respondents completed the DCE: treatment preference appeared to be driven by method of administration (odds ratio [OR] 4.33; 95% confidence interval [CI] 2.88-6.52), frequency of dosing (OR 2.33; 95% CI 1.86-2.92) and drug-food interactions (OR 1.91; 95% CI 1.54-2.37). Respondents preferred therapies delivered orally over subcutaneous injection (OR 4.22; 95% CI 2.76-6.46), dosed once weekly over once daily (OR 2.37; 95% CI 1.58-3.54) and without food restrictions over with restrictions (OR 1.90; 95% CI 1.52-2.38). Sixty-nine respondents completed the DCE and PBS (mean [range] age 53 [19-83] years, 65% female). Seven incomplete PBS responses were excluded from analysis. Respondents were currently, or most recently, receiving eltrombopag (n = 43) or romiplostim (n = 26), of which 30% (n = 21/69) had previously received another TPO-RA. Loss (29%, n = 6/21) and lack (29%, n = 6/21) of response were the most common reasons for switching TPO-RA. Only 28% (n = 18/65) of respondents felt their TPO-RA increased energy levels.

CONCLUSION

Patients preferred therapies delivered orally, dosed less frequently and without food restrictions. QoL of ITP patients on TPO-RAs can be improved; the burden analyses presented can inform future efforts towards this.

Quantitative super-resolution imaging of platelet degranulation reveals differential release of von Willebrand factor and von Willebrand factor propeptide from alpha-granules

BACKGROUND

Von Willebrand factor (VWF) and VWF propeptide (VWFpp) are stored in eccentric nanodomains within platelet alpha-granules. VWF and VWFpp can undergo differential secretion following Weibel-Palade body exocytosis in endothelial cells; however, it is unclear if the same process occurs during platelet alpha-granule exocytosis. Using a high-throughput 3-dimensional super-resolution imaging workflow for quantification of individual platelet alpha-granule cargo, we studied alpha-granule cargo release in response to different physiological stimuli.

OBJECTIVES

To investigate how VWF and VWFpp are released from alpha-granules in response to physiological stimuli.

METHODS

Platelets were activated with protease-activated receptor 1 (PAR-1) activating peptide (PAR-1 ap) or collagen-related peptide (CRP-XL). Alpha-tubulin, VWF, VWFpp, secreted protein acidic and cysteine rich (SPARC), and fibrinogen were imaged using 3-dimensional structured illumination microscopy, followed by semiautomated analysis in FIJI. Uptake of anti-VWF nanobody during degranulation was used to identify alpha-granules that partially released content.

RESULTS

VWFpp overlapped with VWF in eccentric alpha-granule subdomains in resting platelets and showed a higher degree of overlap with VWF than SPARC or fibrinogen. Activation of PAR-1 (0.6-20 μM PAR-1 ap) or glycoprotein VI (GPVI) (0.25-1 μg/mL CRP-XL) signaling pathways caused a dose-dependent increase in alpha-granule exocytosis. More than 80% of alpha-granules remained positive for VWF, even at the highest agonist concentrations. In contrast, the residual fraction of alpha-granules containing VWFpp decreased in a dose-dependent manner to 23%, whereas SPARC and fibrinogen were detected in 60% to 70% of alpha-granules when stimulated with 20 μM PAR-1 ap. Similar results were obtained using CRP-XL. Using an extracellular anti-VWF nanobody, we identified VWF in postexocytotic alpha-granules.

CONCLUSION

We provide evidence for differential secretion of VWF and VWFpp from individual alpha-granules.

Platelet Transfusion before CVC Placement in Patients with Thrombocytopenia

BACKGROUND

Transfusion guidelines regarding platelet-count thresholds before the placement of a central venous catheter (CVC) offer conflicting recommendations because of a lack of good-quality evidence. The routine use of ultrasound guidance has decreased CVC-related bleeding complications.

METHODS

In a multicenter, randomized, controlled, noninferiority trial, we randomly assigned patients with severe thrombocytopenia (platelet count, 10,000 to 50,000 per cubic millimeter) who were being treated on the hematology ward or in the intensive care unit to receive either one unit of prophylactic platelet transfusion or no platelet transfusion before ultrasound-guided CVC placement. The primary outcome was catheter-related bleeding of grade 2 to 4; a key secondary outcome was grade 3 or 4 bleeding. The noninferiority margin was an upper boundary of the 90% confidence interval of 3.5 for the relative risk.

RESULTS

We included 373 episodes of CVC placement involving 338 patients in the per-protocol primary analysis. Catheter-related bleeding of grade 2 to 4 occurred in 9 of 188 patients (4.8%) in the transfusion group and in 22 of 185 patients (11.9%) in the no-transfusion group (relative risk, 2.45; 90% confidence interval [CI], 1.27 to 4.70). Catheter-related bleeding of grade 3 or 4 occurred in 4 of 188 patients (2.1%) in the transfusion group and in 9 of 185 patients (4.9%) in the no-transfusion group (relative risk, 2.43; 95% CI, 0.75 to 7.93). A total of 15 adverse events were observed; of these events, 13 (all grade 3 catheter-related bleeding [4 in the transfusion group and 9 in the no-transfusion group]) were categorized as serious. The net savings of withholding prophylactic platelet transfusion before CVC placement was $410 per catheter placement.

CONCLUSIONS

The withholding of prophylactic platelet transfusion before CVC placement in patients with a platelet count of 10,000 to 50,000 per cubic millimeter did not meet the predefined margin for noninferiority and resulted in more CVC-related bleeding events than prophylactic platelet transfusion. (Funded by ZonMw; PACER Dutch Trial Register number, NL5534.).

Oculocerebrorenal syndrome of Lowe protein controls cytoskeletal reorganisation during human platelet spreading

Lowe syndrome (LS) is a rare, X-linked disorder characterised by numerous symptoms affecting the brain, the eyes, and the kidneys. It is caused by mutations in the oculocerebrorenal syndrome of Lowe (OCRL) protein, a 5-phosphatase localised in different cellular compartments that dephosphorylates phosphatidylinositol-4,5-bisphosphate into phosphatidylinositol-4-monophosphate. Some patients with LS also have bleeding disorders, with normal to low platelet (PLT) count and impaired PLT function. However, the mechanism of PLT dysfunction in patients with LS is not completely understood. The main function of PLTs is to activate upon vessel wall injury and stop the bleeding by clot formation. PLT activation is accompanied by a shape change that is a result of massive cytoskeletal rearrangements. Here, we show that OCRL-inhibited human PLTs do not fully spread, form mostly filopodia, and accumulate actin nodules. These nodules co-localise with ARP2/3 subunit p34, vinculin, and sorting nexin 9. Furthermore, OCRL-inhibited PLTs have a retained microtubular coil with high levels of acetylated tubulin. Also, myosin light chain phosphorylation is decreased upon OCRL inhibition, without impaired degranulation or integrin activation. Taken together, these results suggest that OCRL contributes to cytoskeletal rearrangements during PLT activation that could explain mild bleeding problems in patients with LS.

Lupus anticoagulant associates with thrombosis in patients with COVID-19 admitted to intensive care units: A retrospective cohort study

Background

Thrombosis is a frequent and severe complication in patients with coronavirus disease 2019 (COVID‐19) admitted to the intensive care unit (ICU). Lupus anticoagulant (LA) is a strong acquired risk factor for thrombosis in various diseases and is frequently observed in patients with COVID‐19. Whether LA is associated with thrombosis in patients with severe COVID‐19 is currently unclear.

Objective

To investigate if LA is associated with thrombosis in critically ill patients with COVID‐19.

Patients/Methods

The presence of LA and other antiphospholipid antibodies was assessed in patients with COVID‐19 admitted to the ICU. LA was determined with dilute Russell's viper venom time (dRVVT) and LA‐sensitive activated partial thromboplastin time (aPTT) reagents.

Results

Of 169 patients with COVID‐19, 116 (69%) tested positive for at least one antiphospholipid antibody upon admission to the ICU. Forty (24%) patients tested positive for LA; of whom 29 (17%) tested positive with a dRVVT, 19 (11%) tested positive with an LA‐sensitive aPTT, and 8 (5%) tested positive on both tests. Fifty‐eight (34%) patients developed thrombosis after ICU admission. The odds ratio (OR) for thrombosis in patients with LA based on a dRVVT was 2.5 (95% confidence interval [CI], 1.1–5.7), which increased to 4.5 (95% CI, 1.4–14.3) in patients at or below the median age in this study (64 years). LA positivity based on a dRVVT or LA‐sensitive aPTT was only associated with thrombosis in patients aged less than 65 years (OR, 3.8; 95% CI, 1.3–11.4) and disappeared after adjustment for C‐reactive protein.

Conclusion

Lupus anticoagulant on admission is strongly associated with thrombosis in critically ill patients with COVID‐19, especially in patients aged less than 65 years.

Rilzabrutinib, an Oral BTK Inhibitor, in Immune Thrombocytopenia

BACKGROUND

Rilzabrutinib, an oral, reversible covalent inhibitor of Bruton's tyrosine kinase, may increase platelet counts in patients with immune thrombocytopenia by means of dual mechanisms of action: decreased macrophage (Fcγ receptor)-mediated platelet destruction and reduced production of pathogenic autoantibodies.

METHODS

In an international, adaptive, open-label, dose-finding, phase 1-2 clinical trial, we evaluated rilzabrutinib therapy in previously treated patients with immune thrombocytopenia. We used intrapatient dose escalation of oral rilzabrutinib over a period of 24 weeks; the lowest starting dose was 200 mg once daily, with higher starting doses of 400 mg once daily, 300 mg twice daily, and 400 mg twice daily. The primary end points were safety and platelet response (defined as at least two consecutive platelet counts of ≥50×10³ per cubic millimeter and an increase from baseline of ≥20×10³ per cubic millimeter without the use of rescue medication).

RESULTS

Sixty patients were enrolled. At baseline, the median platelet count was 15×10³ per cubic millimeter, the median duration of disease was 6.3 years, and patients had received a median of four different immune thrombocytopenia therapies previously. All the treatment-related adverse events were of grade 1 or 2 and transient. There were no treatment-related bleeding or thrombotic events of grade 2 or higher. At a median of 167.5 days (range, 4 to 293) of treatment, 24 of 60 patients (40%) overall and 18 of the 45 patients (40%) who had started rilzabrutinib treatment at the highest dose met the primary end point of platelet response. The median time to the first platelet count of at least 50×10³ per cubic millimeter was 11.5 days. Among patients with a primary platelet response, the mean percentage of weeks with a platelet count of at least 50×10³ per cubic millimeter was 65%.

CONCLUSIONS

Rilzabrutinib was active and associated with only low-level toxic effects at all dose levels. The dose of 400 mg twice daily was identified as the dose for further testing. Overall, rilzabrutinib showed a rapid and durable clinical activity that improved with length of treatment. (Funded by Sanofi; ClinicalTrials.gov number, NCT03395210; EudraCT number, 2017-004012-19.).

Platelet degranulation and bleeding phenotype in a large cohort of Von Willebrand disease patients

Von Willebrand disease (VWD) is a bleeding disorder caused by quantitative (type 1 or 3) or qualitative (type 2A/2B/2M/2N) defects of circulating von Willebrand factor (VWF). Circulating VWF levels not always fully explain bleeding phenotypes, suggesting a role for alternative factors, like platelets. Here, we investigated platelet factor 4 (PF4) in a large cohort of patients with VWD. PF4 levels were lower in type 2B and current bleeding phenotype was significantly associated with higher PF4 levels, particularly in type 1 VWD. Based on our findings we speculate that platelet degranulation and cargo release may play a role across VWD subtypes.

Indication and outcome of lupus anticoagulant and antiphospholipid antibodies testing in routine clinical practice

Objectives

Lupus anticoagulans (LACs) and aPLs, both further summarized as aPL, are frequently assessed in routine daily clinical practice in diagnostic workups for suspected autoimmune diseases or to test for underlying risk factors in patients with thrombosis or obstetric complications. The aim of this study was to determine the prevalence of aPL positivity in patients with an indication for aPL testing in routine clinical practice.

Methods

In this retrospective single-centre study, indication for aPL testing, aPL test results and clinical data were collected for patients tested between June 2015 and April 2018.

Results

During the study period, 16 847 single aPL tests were performed in 2139 patients. In 212 patients one or more positive aPL test was found, confirmed in 43.9% with a second positive test. Indications for aPL testing were diagnostic workup/follow-up of autoimmune diseases (33.6%), thrombosis (21.4%) and obstetric complications (28%). Seventy-four patients (3.5% of all patients) fulfilled the criteria of APS, of whom 51% were newly diagnosed. Second positive aPL titres and titres of APS patients were significantly higher compared with positive aPL titres at the first measurement (P < 0.05). Patients with indications of arterial thrombosis and diagnostic workup/follow-up of autoimmune diseases had significantly higher levels of aCL IgG and anti-β2 glycoprotein I (β2GPI) IgG compared with patients with other indications.

Conclusion

The prevalence of one or more positive aPL test was 9.9% and APS was diagnosed in 3.5% of the patients. Patients with arterial thrombosis had significantly higher anti-β2GPI IgG and aCL IgG, which should be confirmed in future studies.

Therapeutic plasma exchange for anticoagulant-refractory antiphospholipid syndrome with severe ischemic and necrotic skin lesions: A case series

Antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by clinical findings including thrombosis and/or obstetric complication and laboratory findings, e.g. ≥1 positive antiphospholipid antibodies (aPL) (lupus anticoagulant, anticardiolipin IgG/IgM and/or anti-β2-glycoprotein IgG/IgM). A rare APS clinical entity is severe necrosis which is difficult to treat and often does not respond to anticoagulant therapy. Three consecutive patients with primary or secondary APS who presented with necrotic skin lesions secondary to APS were treated with therapeutic plasma exchange (TPE), glucocorticoids and low-molecular-weight heparin. All patients had a rapid-onset, either full or significant recovery of their APS-related necrotic lesions. Upon treatment, one patients showed resolution of lupus anticoagulant. Two patients had a decrease of at least 88 % in aPL titers after the initial treatment, and were kept on TPE maintenance every 5-6 weeks. None of the patients experienced significant side effects of the TPE. This is the first case series showing the clinical benefits of TPE in patients with ischemic and necrotic skin lesions due to severe anticoagulant-refractory vascular APS.

Diagnosis and treatment of patients with antiphospholipid syndrome: a mixed-method evaluation of care in The Netherlands

Objectives

The aims were to gain insight into the care provided to patients with APS in The Netherlands and to identify areas for improvement from the perspective of both patients and medical specialists.

Methods

APS care was evaluated using qualitative and quantitative methods. Perspectives on APS care were explored using semi-structured interviews with medical specialists, patient focus groups and a cross-sectional, online patient survey. In order to assess current practice, medical records were reviewed retrospectively to collect data on clinical and laboratory manifestations and pharmacological treatment in six Dutch hospitals.

Results

Fourteen medical specialists were interviewed, 14 patients participated in the focus groups and 79 patients completed the survey. Medical records of 237 patients were reviewed. Medical record review showed that only one-third of patients were diagnosed with APS within 3 months after entering specialist care. The diagnostic approach and management varied between centres and specialists. Almost 10% of all patients and 7% of triple-positive patients with thrombotic APS were not receiving any anticoagulant treatment at the time of medical record review. Correspondingly, poor recognition and fragmentation of care were reported as the main problems by medical specialists. Additionally, patients reported the lack of accessible, reliable patient education, psychosocial support and trust in physicians as important points for improvement.

Conclusion

Delayed diagnosis, variability in management strategies and fragmentation of care were important limitations of APS care identified in this study. A remarkable 10% of patients did not receive any anticoagulant treatment.

Severe postpartum haemorrhage as first presenting symptom of an inherited bleeding disorder

INTRODUCTION

Postpartum haemorrhage (PPH) is the major cause of maternal death worldwide. Haemostatic abnormalities are independently associated with a significantly increased risk for severe PPH. In this study, the value of haemostatic evaluation in women with severe PPH was explored.

AIM

To investigate the occurrence of previously unknown inherited bleeding disorders in women with severe PPH.

METHODS

Women with severe PPH (blood loss of ≥2000 mL) between 2011 and 2017, referred to the haematology outpatient clinic for haemostatic evaluation, were retrospectively included. A bleeding disorder was diagnosed based on (inter)national guidelines, or when having a clear bleeding phenotype, not fulfilling any diagnostic criteria or laboratory abnormalities, this being classified as Bleeding of Unknown Cause (BUC). Logistic regression was used to model the association between diagnosis and obstetrical causes and risk factors for PPH.

RESULTS

In total, 85 women with PPH were included. In 23% (n = 16), a mild bleeding disorder was diagnosed, including low von Willebrand factor (Low VWF 8/16), platelet function disorders (PFD 5/16), BUC (2/16) and von Willebrand disease type 1 (1/16). No significant associations were found between obstetrical causes or risk factors for PPH and the presence of a bleeding disorder.

CONCLUSION

In 23% of women with severe PPH, a mild bleeding disorder was diagnosed, independent of obstetrical causes or risk factors for PPH. This implies that severe PPH can be the first clinical symptom of an inherited bleeding disorder. Therefore, to optimize clinical management, haemostatic evaluation after severe PPH is recommended.

Diagnosing and treating antiphospholipid syndrome: a consensus paper

INTRODUCTION

The antiphospholipid syndrome (APS) is defined by the occurrence of venous and/or arterial thrombosis and/or pregnancy-related morbidity, combined with the presence of antiphospholipid antibodies (aPL) and/or a lupus anticoagulant (LAC). Large, controlled, intervention trials in APS are limited. This paper aims to provide clinicians with an expert consensus on the management of APS.

METHODS

Relevant papers were identified by literature search. Statements on diagnostics and treatment were extracted. During two consensus meetings, statements were discussed, followed by a Delphi procedure. Subsequently, a final paper was written.

RESULTS

Diagnosis of APS includes the combination of thrombotic events and presence of aPL. Risk stratification on an individual base remains challenging. 'Triple positive' patients have highest risk of recurrent thrombosis. aPL titres > 99th percentile should be considered positive. No gold standard exists for aPL testing; guidance on assay characteristics as formulated by the International Society on Thrombosis and Haemostasis should be followed. Treatment with vitamin K-antagonists (VKA) with INR 2.0-3.0 is first-line treatment for a first or recurrent APS-related venous thrombotic event. Patients with first arterial thrombosis should be treated with clopidogrel or VKA with target INR 2.0-3.0. Treatment with direct oral anticoagulants is not recommended. Patients with catastrophic APS, recurrent thrombotic events or recurrent pregnancy morbidity should be referred to an expert centre.

CONCLUSION

This consensus paper fills the gap between evidence-based medicine and daily clinical practice for the care of APS patients.

Anti-HLA antibodies with complementary and synergistic interaction geometries promote classical complement activation on platelets

High titers of HLA antibodies are associated with platelet refractoriness, causing poor platelet increments after transfusions in a subset of patients with HLA antibodies. Currently, we do not know the biological mechanisms that explain the variability in clinical responses in HLA alloimmunized patients receiving platelet transfusions. Previously we showed that a subset of anti-HLA IgG-antibodies induces FcγRIIa-dependent platelet activation and enhanced phagocytosis. Here, we investigated whether anti-HLA IgG can induce complement activation on platelets. We found that a subset of anti-HLA IgG induced complement activation via the classical pathway, causing C4b and C3b deposition and formation of the membrane-attack complex. This resulted in permeabilization of platelet membranes and increased calcium influx. Complement activation also caused enhanced α-granule release, as measured by CD62P surface exposure. Blocking studies revealed that platelet activation was caused by FcγRIIa-dependent signaling as well as HLA antibody induced complement activation. Synergistic complement activation employing combinations of monoclonal IgGs suggested that assembly of oligomeric IgG complexes strongly promoted complement activation through binding of IgGs to different antigenic determinants on HLA. In agreement with this, we observed that preventing anti-HLA-IgG hexamer formation using an IgG-Fc:Fc blocking peptide, completely inhibited C3b and C4b deposition. Our results show that HLA antibodies can induce complement activation on platelets including membrane attack complex formation, pore formation and calcium influx. We propose that these events can contribute to fast platelet clearance in vivo in patients refractory to platelet transfusions with HLA alloantibodies, who may benefit from functional-platelet matching and treatment with complement inhibitors.

A subset of anti-HLA antibodies induces FcγRIIa-dependent platelet activation

HLA antibodies are associated with refractoriness to platelet transfusion, leading to rapid platelet clearance, sometimes coinciding with clinical side effects such as fever and chills. The presence of HLA antibodies is not always manifested by clinical symptoms. It is currently unclear why refractoriness to platelet transfusion is only observed in a subset of patients. Here, we utilized the availability of a unique panel of human monoclonal antibodies to study whether these were capable of activating platelets. Three out of eight human HLA-specific monoclonal antibodies induced activation of HLA-matched platelets from healthy donors as evidenced by enhanced α-granule release, aggregation, and α_IIbb₃ activation. The propensity of HLA monoclonal antibodies to activate platelets was independent of the HLA subtype to which they were directed, but was dependent on the recognized epitope. Activation was fully inhibited either by blocking FcγRIIa, or by blocking FcγRIIa-dependent signaling with Syk inhibitor IV. Furthermore, activation required the presence of the IgG-Fc part, as F(ab’)₂ fragments of HLA monoclonal antibodies were unable to induce platelet activation. Mixing experiments revealed that activation of platelets occurred in an intra-platelet dependent manner. Accordingly, a proportion of sera from refractory patients with HLA antibodies induced FcγRIIa-dependent platelet activation. Our data show that a subset of HLA antibodies is capable of crosslinking HLA and FcγRIIa thereby promoting platelet activation and enhancing these cells’ phagocytosis by macrophages. Based on these findings we suggest that FcγRIIa-dependent platelet activation may contribute to the decreased platelet survival in platelet-transfusion-dependent patients with HLA antibodies.

Emerging Concepts in Immune Thrombocytopenia

Immune thrombocytopenia (ITP) is an autoimmune disease defined by low platelet counts which presents with an increased bleeding risk. Several genetic risk factors (e.g., polymorphisms in immunity-related genes) predispose to ITP. Autoantibodies and cytotoxic CD8⁺ T cells (Tc) mediate the anti-platelet response leading to thrombocytopenia. Both effector arms enhance platelet clearance through phagocytosis by splenic macrophages or dendritic cells and by induction of apoptosis. Meanwhile, platelet production is inhibited by CD8⁺ Tc targeting megakaryocytes in the bone marrow. CD4⁺ T helper cells are important for B cell differentiation into autoantibody secreting plasma cells. Regulatory Tc are essential to secure immune tolerance, and reduced levels have been implicated in the development of ITP. Both Fcγ-receptor-dependent and -independent pathways are involved in the etiology of ITP. In this review, we present a simplified model for the pathogenesis of ITP, in which exposure of platelet surface antigens and a loss of tolerance are required for development of chronic anti-platelet responses. We also suggest that infections may comprise an important trigger for the development of auto-immunity against platelets in ITP. Post-translational modification of autoantigens has been firmly implicated in the development of autoimmune disorders like rheumatoid arthritis and type 1 diabetes. Based on these findings, we propose that post-translational modifications of platelet antigens may also contribute to the pathogenesis of ITP.

Evaluation of the role of the GPIb-IX-V receptor complex in development of the platelet storage lesion

BACKGROUND AND OBJECTIVES

In mice, loss of sialic acid resulting in shedding of glycoprotein (GP) Ibα and GPV has been linked to platelet survival. The aim of this study was to determine whether loss of sialic acid and the GPIb-IX-V complex contributes to development of the platelet storage lesion (PSL) in human platelet concentrates (PCs).

MATERIALS AND METHODS

PCs (stored in plasma (with or without Mirasol treatment); PAS-C or PAS-E) were stored at room temperature. Flow cytometry was used to monitor membrane expression of the GPIb-IX-V complex, CD62P, surface glycans and PS exposure. The functionality of stored platelets was determined employing aggregometry and ristocetin-induced VWF binding.

RESULTS

Storage time of PCs in blood banks is limited to 7 days. During this time period, a minor but gradually increasing subpopulation of GPIbα-negative platelets was observed. Also, ristocetin-induced VWF binding was impaired in a small population of platelets. Mean surface expression of GPIbα and GPV remained stable until day 9, whereas CD62P expression increased; also a rapid decrease in ADP-induced aggregation was observed for PAS-C, PAS-E and Mirasol-treated PCs. Upon prolonged storage (>9 days), a slow decline in surface expression of GPIbα and GPV was observed; no major changes were observed in surface sialylation with the exception of Mirasol-treated platelets.

CONCLUSION

In a small population of stored platelets, changes in GPIbα occur from day 2 onwards. Loss of sialic acid and subsequent shedding of GPIbα and GPV is not an early event during the development of the PSL.

Well being of obstetric patients on minimal blood transfusions (WOMB trial)

Background

Primary postpartum haemorrhage is an obstetrical emergency often causing acute anaemia that may require immediate red blood cell (RBC) transfusion. This anaemia results in symptoms such as fatigue, which may have major impact on the health-related quality of life. RBC transfusion is generally thought to alleviate these undesirable effects although it may cause transfusion reactions. Moreover, the postpartum haemoglobin level seems to influence fatigue only for a short period of time. At present, there are no strict transfusion criteria for this specific indication, resulting in a wide variation in postpartum policy of RBC transfusion in the Netherlands.

Methods/Design

The WOMB trial is a multicentre randomised non-inferiority trial. Women with acute anaemia due to postpartum haemorrhage, 12-24 hours after delivery and not initially treated with RBC transfusion, are eligible for randomisation. Patients with severe physical complaints are excluded. Patients are randomised for either RBC transfusion or expectant management. Health related quality of life (HRQoL) will be assessed at inclusion, at three days and one, three and six weeks postpartum with three validated measures (Multi-dimensional Fatigue Inventory, ShortForm-36, EuroQol-5D). Primary outcome of the study is physical fatigue three days postpartum. Secondary outcome measures are general and mental fatigue scores and generic health related quality of life scores, the number of RBC transfusions, length of hospital stay, complications and health-care costs.

The primary analysis will be by intention-to-treat. The various longitudinal scores will be evaluated using Repeated Measurements ANOVA. A costs benefit analysis will also be performed. The power calculation is based on the exclusion of a difference in means of 1.3 points or greater in favour of RBC transfusion arm regarding physical fatigue subscale. With missing data not exceeding 20%, 250 patients per arm have to be randomised (one-sided alpha = 0.025, power = 80%).

Discussion

This study will provide evidence for a guideline regarding RBC transfusion in the postpartum patient suffering from acute anaemia. Equivalence in fatigue score, remaining HRQoL scores and physical complications between both groups is assumed, in which case an expectant management would be preferred to minimise transfusion reactions and costs.

Trial registration

ClinicalTrials.gov NCT00335023, Nederlands Trial Register NTR335

[Multicentre clinical study into the optimal blood transfusion policy in patients with postpartum haemorrhage: the 'Wellbeing of obstetric patients on minimal blood transfusions' (WOMB) study]

Postpartum haemorrhage is a common and potentially serious complication of delivery. In clinical obstetrics, exact measurement of blood loss is often difficult. Red blood cell (RBC) transfusion is the most important intervention to treat the complications of this sustained blood loss. Despite the introduction of various new guidelines, the triggers for transfusion still vary widely between clinicians. Therefore, a prospective randomised multicentre trial, the 'Wellbeing of obstetric patients on minimal blood transfusions' (WOMB) study, was developed. This study assesses the effect of RBC transfusion on the health-related quality of life (HRQoL) of the mother after delivery. Patients with a haemoglobin (Hb) level between 3.0 and 4.9 mmol/l and a blood loss of at least 1000 ml or a decrease of > 1.2 mmol/l in the Hb level are randomly assigned to receive RBC transfusion or not. A total of 400 patients will be included. Primary outcome is physical fatigue. The total follow-up period is 6 weeks. Currently, the study is ongoing in 10 hospitals in the Netherlands. The goal of this study is to develop a new transfusion policy based on Hb-levels as well as HRQoL criteria.

Psychometric evaluation of health-related quality of life measures in women after different types of delivery

OBJECTIVE

We examined the psychometric properties of three internationally established measures for health-related quality of life (HRQoL) in women after vaginal delivery (VD), elective cesarean section (CS), and emergency CS and the relationship of HRQoL scores with blood loss after delivery.

METHODS

This is a prospective longitudinal study. One hundred forty-one consecutive patients (71 after VD, 36 after elective CS, and 34 after emergency CS) were enrolled in two university hospitals and one general hospital from June 2003 to March 2004. Women completed the Multidimensional Fatigue Inventory (MFI) and the EQ-5D classification of own health between 12 and 24 h after VD or between 24 and 48 h after CS. Subsequent assessments, additionally including the Short Form 36 (SF-36), were made 1, 3, and 6 weeks after delivery. We analyzed feasibility (response, completion time, reported difficulties, item nonresponse), reliability (Cronbach's alpha), discriminative validity between groups by type of delivery, and responsiveness over time (Wilcoxon's signed rank tests and effect sizes).

RESULTS

The MFI, SF-36, and EQ-5D proved to be highly feasible and reliable (alpha>.7 for all scales of MFI and SF-36). The measures were able to discriminate between groups by mode of delivery and to detect moderate recovery in physical and small recovery in mental status over time in the first 6 weeks after delivery. The suboptimal total questionnaire response of 60% after 6 weeks was attributable to low response among women of non-Dutch ethnic origin. The significant correlation between Hb level and mean physical HRQoL scores found at T=0 disappeared 1 week postpartum.

CONCLUSION

The combination of MFI, SF-36, and EQ-5D showed good psychometric performance and is a good choice to measure HRQoL after delivery in scientific studies. Development of a shorter set is needed for use in routine clinical practice.

New insights into fatigue and health-related quality of life after delivery

BACKGROUND

A delivery has a major impact on the health-related quality of life (HRQoL) of the new mother, especially on fatigue. A common complication during delivery that might have a relationship with maternal morbidity is blood loss. The objectives were to investigate fatigue and HRQoL in women after vaginal delivery (VD), elective caesarean section (CS) and emergency CS, and its relationship with postpartum hemoglobin (Hb) levels during the first 6 weeks postpartum.

METHODS

Some 141 patients (71 after VD, 36 after elective CS and 34 after emergency CS) completed the HRQoL questionnaires MFI and EQ-5D between 12 and 24 h after VD and 24-48 h after CS (t=0). At 1, 3 and 6 weeks postpartum these questionnaires were repeated, together with the SF36.

RESULTS

Patients after VD had higher mean physical HRQoL scores than after CS. The average period to reach full physical recovery was 3 weeks after VD, 6 weeks after elective CS, and >6 weeks after emergency CS. Mean mental HRQoL scores of the study groups were similar or even better compared to reference values. The significant correlation between Hb level and mean physical HRQoL scores found at t=0 had disappeared at 1 week postpartum.

CONCLUSIONS

Results of this study provided insights into the natural course of fatigue and HRQoL postpartum. Important differences in fatigue and HRQoL scores were observed between the 3 modes of delivery. These HRQoL measures can be used in future clinical trials to assess the effects of interventions postpartum.

Postpartum hemorrhage and transfusion of blood and blood components

Postpartum hemorrhage (PPH) is one of the top 5 causes of maternal mortality in developed and developing countries. The incidence of PPH is 40% after vaginal delivery and 30% after cesarean section. Criteria for PPH are based on the amount of blood loss. In clinical obstetrics, exact measurement of blood loss is often difficult. The most important treatment of PPH is red blood cell (RBC) transfusion. In the past few years, increasing concern has arisen about this treatment. Despite the introduction of several new guidelines, transfusion criteria still vary widely between clinicians. The decision whether to prescribe RBC transfusion is mostly based on postpartum hemoglobin (Hb) values. RBC transfusion should be aimed to reduce morbidity and especially to improve health-related quality of life (HRQoL). In this review, etiology, epidemiology, treatment, and prevention of postpartum hemorrhage are described. Special attention is given to the role of RBC transfusion in the treatment of PPH and the effects of RBC transfusion on HRQoL.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to summarize the new guidelines related to transfusion criteria, explain the importance of reducing morbidity related to improving quality of life issues, and list infectious and noninfectious complications of a red blood cell transfusion.

Feasibility of a restrictive red-cell transfusion policy for patients treated with intensive chemotherapy for acute myeloid leukaemia

Red-cell transfusions are required for symptomatic treatment of severe anaemia caused by intensive chemotherapy. Concerns about the transfusion-related complications, such as infections (e.g. the very low risk of human immunodeficiency virus (HIV)/hepatitis C virus (HCV) transmission and the risk of postoperative infections), haemolytic transfusion reaction, immunological effects and the costs, prompt a reevaluation of the transfusion practice. Retrospective analysis of prospectively collected data on 84 patients with acute myeloid leukaemia (AML), who were treated with combination chemotherapy between June 1, 1997 and December 7, 2001, was performed. The use of red-cell transfusions with a restrictive transfusion policy (haemoglobin = 7.2-8.8 g dL(-1), dependent on age and symptoms, n = 38) was compared with a more liberal transfusion trigger (haemoglobin = 9.6 g dL(-1), n = 46). The number of units transfused was recorded. Signs and symptoms of anaemia, chemotherapy-related effects and complications were investigated for both transfusion policies. The more restrictive transfusion policy led to a significant decrease of 11% of red blood cell (RBC) transfusions in patients with AML. No significant differences were found in the incidence of infections, number of platelet units transfused, bleeding complications, cardiac symptoms or response to chemotherapy. The more restrictive transfusion policy was feasible in this clinical setting, and it might be concluded that a restrictive transfusion policy is safe in supporting clinical patients treated with intensive chemotherapy for AML.

Quality of life measurement in patients with transfusion-dependent myelodysplastic syndromes

The myelodysplastic syndromes (MDS) are clonal disorders characterized by dysplasia in at least two myeloid cell lines. Fatigue is one of the most significant symptoms. MDS patients are treated with blood transfusions to improve their health-related quality of life (HRQoL). A cross-sectional pilot study was performed for psychometric evaluation of three internationally established HRQoL measures in MDS patients, and for investigation of the association between the severity of chronic anaemia and HRQoL. Fifty consecutive MDS patients completed the Short Form 36, the Multidimensional Fatigue Inventory and the EuroQoL-5D Visual Analogue Scale. Hb level was measured during the same visit. Psychometric analysis focused on feasibility, construct validity and reliability. The questionnaires showed a high feasibility, reliability and validity. MDS patients had worse HRQoL scores than the age- and sex-matched general population. We found a positive correlation between haemoglobin (Hb) level and HRQoL. This study provides insights into the suitability of established HRQoL measures for the evaluation of interventions in MDS patients. Hb value and HRQoL are complementary variables for evaluation of the severity of chronic anaemia in patients with MDS.