Prophylactic tranexamic acid in patients with hematologic malignancy: a placebo-controlled, randomized clinical trial

Platelet transfusion

PURPOSE OF REVIEW

Platelet transfusions, used as prophylaxis or treatment for bleeding, are potentially life-saving. In many countries, demand for platelet transfusion is rising. Platelets are a limited and costly resource, and it is vital that they are used appropriately. This study will explore the evidence behind platelet transfusions in different contexts, in particular recent and important research in this area.

RECENT FINDINGS

Recent randomized clinical trials demonstrate the efficacy of platelet transfusions in some contexts but potential detrimental effects in others. Platelet transfusions also carry risk of transfusion reactions, bacterial contamination and platelet transfusion refractoriness. Observational and clinical studies, which highlight approaches to mitigate these risks, will be discussed. There is growing interest in cold-stored or cryopreserved platelet units, which may improve platelet function and availability. Clinical trials also highlight the efficacy of other supportive measures such as tranexamic acid or thrombopoietin receptor agonists in patients with bleeding.

SUMMARY

Although platelet transfusions are beneficial in many patients, there remain many settings in which the optimal use of platelet transfusions is unclear, and some situations in which they may have detrimental effects. Future clinical trials are needed to determine optimal use of platelet transfusions in different patient populations.

Tranexamic acid versus placebo to prevent bleeding in patients with haematological malignancies and severe thrombocytopenia (TREATT): a randomised, double-blind, parallel, phase 3 superiority trial

BACKGROUND

Bleeding is common in patients with haematological malignancies undergoing intensive therapy. We aimed to assess the effect of tranexamic acid on preventing bleeding and the need for platelet transfusions.

METHODS

TREATT was an international, randomised, double-blind, parallel, phase 3 superiority trial conducted at 27 haematology centres in Australia and the UK. We enrolled adults (aged ≥18 years) receiving intensive chemotherapy or haematopoietic stem-cell transplantation for a haematological malignancy, with a platelet count of 10 × 109 platelets per L or less for 5 days or longer. Patients were randomly assigned (1:1) using block randomisation, stratified by site, to tranexamic acid (1 g every 8 h intravenously or 1·5g every 8 h orally) or placebo when their platelet count was less than 30 × 109 platelets per L. Treatment was continued until platelet recovery or day 30. Prophylactic platelet transfusions were maintained as standard of care. The primary endpoint was the proportion of patients who died or had WHO grade 2 or higher bleeding up to day 30. A modified intention-to-treat population including randomly assigned patients whose platelet count decreased to 30 × 109 platelets per L or less was used for analysis. This trial is registered with ClinicalTrials.gov (NCT03136445), ISRCTN (ISRCTN73545489), and the European Clinical Trials Register (EudraCT 2014-001513-35).

FINDINGS

Between June 23, 2015, and Feb 17, 2022, 1736 patients were screened for eligibility, 616 of whom were enrolled and randomly assigned (310 to tranexamic acid and 306 to placebo). 19 participants were excluded from the modified intention-to-treat analysis, leaving 300 participants in the tranexamic acid group and 297 in the placebo group. Participant median age was 58 years (IQR 49-65), 380 (62%) of 616 participants were male, and 235 (38%) were female. The proportion of participants who died or had WHO grade 2 or higher bleeding was 31·7% (90/298 [95% CI 26·6-37·4]) in the tranexamic acid group and 34·2% (98/295 [29·0-40·0]) in the placebo group (hazard ratio 0·92 [95% CI 0·67-1·27]; p=0·62). There were no differences in thrombotic events or veno-occlusive disease. 94 serious adverse events in 77 participants were reported up to day 60 in the tranexamic acid group and 103 events in 82 participants in the placebo group.

INTERPRETATION

There is insufficient evidence to support routine use of tranexamic acid to reduce bleeding in patients with haematological malignancies undergoing intensive chemotherapy.

FUNDING

UK National Health Service Blood and Transplant and Australian National Health and Medical Research Council.

Analysis of bleeding outcomes in patients with hypoproliferative thrombocytopenia in the A-TREAT clinical trial

BACKGROUND

Despite prophylactic platelet transfusions, hypoproliferative thrombocytopenia is associated with bleeding; historical risk factors include hematocrit (HCT) ≤ 25%, activated partial thromboplastin time ≥ 30 s, international normalized ratio ≥ 1.2, and platelets ≤ 5000/μL.

METHODS

We performed a post hoc analysis of bleeding outcomes and risk factors in participants with hematologic malignancy and hypoproliferative thrombocytopenia enrolled in the American Trial to Evaluate Tranexamic Acid Therapy in Thrombocytopenia (A-TREAT) and randomized to receive either tranexamic acid (TXA) or placebo.

RESULTS

World Health Organization (WHO) grade 2+ bleeding occurred in 46% of 330 participants, with no difference between the TXA (44%) and placebo (47%) groups (p = 0.66). Overall, the most common sites of bleeding were oronasal (18%), skin (17%), gastrointestinal (11%), and genitourinary (11%). Among participants of childbearing potential, 28% experienced vaginal bleeding. Platelets ≤5000/μL and HCT < 21% (after adjusting for severe thrombocytopenia) were independently associated with increased bleeding risk (HR 3.78, 95% CI 2.16-6.61; HR 2.67, 95% CI 1.35-5.27, respectively). Allogeneic stem cell transplant was associated with nonsignificant increased risk of bleeding versus chemotherapy alone (HR 1.34, 95% CI 0.94-1.91).

DISCUSSION

The overall rate of WHO grade 2+ bleeding was similar to previous reports, albeit with lower rates of gastrointestinal bleeding. Vaginal bleeding was common in participants of childbearing potential. Platelets ≤5000/μL remained a risk factor for bleeding. Regardless of platelet count, bleeding risk increased with HCT < 21%, suggesting a red blood cell transfusion threshold above 21% should be considered to mitigate bleeding. More investigation is needed on strategies to reduce bleeding in this population.

RBCs regulate platelet function and hemostasis under shear conditions through biophysical and biochemical means

ABSTRACT

Red blood cells (RBCs) have been hypothesized to support hemostasis by facilitating platelet margination and releasing platelet-activating factors such as adenosine 5'-diphosphate (ADP). Significant knowledge gaps remain regarding how RBCs influence platelet function, especially in (patho)physiologically relevant hemodynamic conditions. Here, we present results showing how RBCs affect platelet function and hemostasis in conditions of anemia, thrombocytopenia, and pancytopenia and how the biochemical and biophysical properties of RBCs regulate platelet function at the blood and vessel wall interface and in the fluid phase under flow conditions. We found that RBCs promoted platelet deposition to collagen under flow conditions in moderate (50 × 103/μL) but not severe (10 × 103/μL) thrombocytopenia in vitro. Reduction in hematocrit by 45% increased bleeding in mice with hemolytic anemia. In contrast, bleeding diathesis was observed in mice with a 90% but not with a 60% reduction in platelet counts. RBC transfusion improved hemostasis by enhancing fibrin clot formation at the site of vascular injury in mice with severe pancytopenia induced by total body irradiation. Altering membrane deformability changed the ability of RBCs to promote shear-induced platelet aggregation. RBC-derived ADP contributed to platelet activation and aggregation in vitro under pathologically high shear stresses, as observed in patients supported by left ventricular assist devices. These findings demonstrate that RBCs support platelet function and hemostasis through multiple mechanisms, both at the blood and vessel wall interface and in the fluidic phase of circulation.

Rare bleeding disorders: Advances in management

Inherited factor coagulation deficiencies and vascular bleeding disorders, associated with bleeding of various severity, are often classified as rare bleeding disorders (RBDs). These include inherited fibrinogen disorders, inherited platelet function disorders (IPFD) and hereditary haemorrhagic telangiectasia (HHT). In the last decades, there have been large increases in knowledge on the epidemiology, genetics, physiopathology, clinical features, and diagnosis of RBDs, but improvements in management have been more limited and remain challenging. The treatment mainstay of RBDs is based only on replacement of a few available coagulation factor concentrates or cryoprecipitates. There is growing interest in therapeutic agents that enhance coagulation or inhibiting anticoagulant pathways in RBDs. In severe IPFD, the optimal platelet transfusion strategy is not yet established. Moreover, data is scarce on the effectiveness and safety of desmopressin and/or antifibrinolytic drugs often used for milder IPFD treatment. The best fibrinogen replacement strategy (prophylaxis vs. on demand) in afibrinogenemia is still debated. Similarly, the optimal trough fibrinogen target level for treatment of acute bleeding, and the role of fibrinogen replacement during pregnancy in mild hypofibrinogenemia and dysfibrinogenemia, have not been properly evaluated. The therapeutic arsenal in HHT includes antifibrinolytics and a series of antiangiogenic agents whose potential efficacy has been tested in small studies or are under investigation for treatment of bleeding. However, there is need to address several issues, including the optimal dosing strategies, the potential emergent toxicity of longer-term use, and the impact of systemic antiangiogenic treatment on visceral arteriovenous malformations.

Use of platelet transfusions and tranexamic acid in patients with myelodysplastic syndromes: A clinical practice survey

AIM

Thrombocytopenia and bleeding are common in myelodysplastic syndromes (MDS), but optimal management is unknown. We conducted a survey to identify current clinical practice regarding platelet transfusion (PLT-T) and tranexamic acid (TXA) to inform future trial design.

METHOD

A 25-question survey was distributed to members of the ALLG from December 2020 to July 2021.

RESULTS

Sixty-four clinicians across Australia, New Zealand and Singapore responded. Clinicians treated a median of 15 MDS patients annually. Twenty-nine (45%) reported having institutional guidelines regarding prophylactic PLT-T. Although 60 (94%) said they would consider using TXA, most (58/64; 91%) did not have institutional guidelines. Clinical scenarios showed prophylactic PLT-T was more likely administered for patients on disease-modifying therapy (49/64; 76%, commonest threshold <10 × 109 /L) or with minor bleeding (32/64 [50%] transfusing at threshold <20 × 109 /L, 23/64 [35%] at <10 × 109 /L). For stable untreated patients, 29/64 (45%) would not give PLT-T and 32/64 (50%) would. Most respondents (46/64; 72%) were interested in participating in trials in this area. Potential barriers included resource limitations, funding and patient/clinician acceptance.

CONCLUSION

Real-world management of MDS-related thrombocytopenia varies and there is a need for clinical trials to inform practice.

The effect of ε-aminocaproic acid on blood product requirement, outcome and thromboelastography parameters in severely thrombocytopenic dogs

BACKGROUND

No treatment other than platelet administration is known to protect against spontaneous hemorrhage in thrombocytopenic dogs.

OBJECTIVES

Primary: determine if treatment with ε-aminocaproic acid (EACA) decreases the requirement for blood transfusions and improves outcome in dogs with severe thrombocytopenia. Secondary: find evidence of hyperfibrinolysis and determine the effect EACA administration on rapid (rTEG) and tissue plasminogen activator-spiked (tPA-rTEG) thromboelastography parameters.

ANIMALS

Twenty-seven dogs with severe thrombocytopenia were treated with EACA, and data from an additional 33 were obtained from the hospital database as historical control (HC) cohort.

METHODS

Single arm clinical trial with HCs. The EACA group dogs received EACA (100 mg/kg IV followed by a constant-rate infusion [CRI] of 400 mg/kg/24 hours). Thromboelastography before and during EACA infusion, hospitalization days, number of transfusions, and mortality were compared.

RESULTS

No difference was found in number of transfusions per dog (median, interquartile range; 1, 0-2.5 vs 0.9, 0-2; P = .5) and hospitalization days (4, 4-6 vs 4.5, 3.75-6; P = .83) between HC and EACA groups, respectively, and no difference in survival was identified by log-rank analysis (P = .15). Maximum amplitude on both rTEG and tPA-rTEG increased after EACA administration (rTEG baseline: 23.6, 9.6-38.9; post-EACA: 27.3, 19.8-43.2; P < .001; tPA-rTEG baseline: 23, 10.9-37.2; post-EACA: 24.7, 16.7-44.8; P < .002).

CONCLUSIONS AND CLINICAL IMPORTANCE

Although EACA increased clot strength, there was no effect on outcome. Treatment with EACA at this dosage cannot be recommended as a routine treatment but may be considered for dogs with severe ongoing hemorrhage.

Fewer severe infections with tranexamic acid in patients with hematologic malignancies

Background

Tranexamic acid (TXA) is an antifibrinolytic agent that reduces bleeding in a multitude of clinical settings from postpartum hemorrhage to trauma. TXA may have clinical effects unrelated to bleeding; plasminogen, the target of TXA, alters immune responses, and TXA appears to decrease the risk of infection in patients undergoing cardiac surgery, as well as joint arthroplasty.

Objectives

To address whether TXA alters rates of infection and inflammatory outcomes in patients with hematologic malignancies.

Methods

We performed a post hoc analysis of outcomes of patients randomized to receive either TXA or placebo in the double-blinded, multicenter American Trial to Evaluate Tranexamic Acid Therapy in Thrombocytopenia (Clinicaltrials.gov identifier: NCT02578901).

Results

TXA did not change the overall rate of infections, but the rate of severe infections (Common Toxicology Criteria for Adverse Events grade 3+) was lower in patients who received TXA compared with the placebo group. Patients who experienced grade 3+ infections had higher rates of World Health Organization grade 2+ bleeding and red blood cell transfusion requirements than patients who did not experience a grade 3+ infection, irrespective of treatment group. TXA did not impact other inflammatory outcomes such as mucositis, rash, or graft vs host disease.

Conclusion

Patients with hematologic malignancies who received TXA had less severe infections than those who received placebo with no difference in overall rate of infection or other inflammatory outcomes. Further investigation is needed on the impact of TXA on infections in this population.

How I treat von Willebrand disorders in older adults

ABSTRACT

von Willebrand disease (VWD) is the most common bleeding disorder and especially milder type 1 VWD might not be cared for in specialty clinics. VW factor levels rise with age, but the rise of these levels does not necessarily correlate with bleeding risk. A recent bleeding history combined with recent labs are important for hemostatic management decision during surgical interventions. Antifibrinolytics appear safe in the population of older adults, whereas desmopressin (DDAVP) should be used cautiously. Where needed, factor concentrates present a great treatment option. Acquired von Willebrand syndrome is vastly underrecognized, but likely to surface in the aging, especially in the setting of comorbidities, such as plasma-cell dyscrasias. Intravenous immunoglobulin can be an effective treatment in this scenario, but potentially increases thrombotic risk.

Management of chemotherapy-induced thrombocytopenia: guidance from the ISTH Subcommittee on Hemostasis and Malignancy

Thrombocytopenia is a common adverse effect of chemotherapy. The development of chemotherapy-induced thrombocytopenia (CIT) is influenced by cancer type and therapy, occurring in approximately one-third of patients with a solid tumor diagnosis and half of all patients with a hematologic malignancy. CIT may complicate the administration of chemotherapy, leading to therapeutic delays or dose reductions. This guidance document, presented by the International Society on Thrombosis and Haemostasis (ISTH) Subcommittee on Hemostasis and Malignancy, provides a comprehensive summary of the evidence and offers direction on the use of thrombopoietin receptor agonists (TPO-RAs) in various settings of CIT, including solid tumors, acute myeloid leukemia, stem cell transplant, and lymphoma. Studies have shown that TPO-RAs can improve platelet counts in CIT, but the clinical benefits of TPO-RA in terms of reducing bleeding, limiting platelet transfusion, avoiding chemotherapy delay, or dose reduction are uncertain. Further research is needed to optimize the selection of appropriate indications and study design to manage thrombocytopenia following chemotherapy.

How to manage ITP with life-threatening bleeding

While immune thrombocytopenia often presents with mild bleeding manifestations or surprising findings of thrombocytopenia on routine complete blood counts in patients without symptoms, some patients can present with new thrombocytopenia and life-threatening bleeding. Emergent assessment and treatment are needed to prevent substantial morbidity and even mortality. These patients present to the emergency room with bleeding, and hematologists are subsequently consulted. Understanding the approach to making the diagnosis and excluding other life-threatening illnesses is essential, as is rapid initiation of treatment in the bleeding patient even when the diagnosis of immune- mediated thrombocytopenia is tentative. Using a case-based format, we review how to approach and treat patients presenting with new thrombocytopenia and bleeding.

Therapeutic plasma exchange in alloimmune platelet refractoriness

Patients with alloimmune platelet refractoriness can present complex clinical conundrums. Herein we describe a case of platelet refractoriness in the setting of combined HLA and HPA alloimmunization in a patient with acute myeloid leukemia and life-threatening bleeding. We discuss causative antibodies and compare prevailing therapeutic modalities. We highlight plasma exchange as a potentially feasible, repeatable, and personalized treatment option for patients with extensive platelet alloimmunization who require transfusion.

Platelet transfusions and predictors of bleeding in patients with myelodysplastic syndromes

OBJECTIVES

This study aimed to describe the burden of thrombocytopenia, supportive care practices, bleeding complications and predictors of bleeding in MDS patients within a large Australian hospital network, to better understand the use and effectiveness of platelet transfusions in MDS.

METHODS

A retrospective cohort study of patients aged ≥18 years with MDS, chronic myelomonocytic leukaemia or MDS/myeloproliferative overlap neoplasm admitted from 2016 to 2018 was conducted. Data were obtained from hospital medical records.

RESULTS

One hundred seventy-nine patients (median age 78 years, 61.5% male) were identified. The median platelet count at first admission was 90 × 109 /L. Twenty-eight (15.6%) patients had severe thrombocytopenia (platelet count <20 × 109 /L), of whom nine (32.1%) received prophylactic platelet transfusions, five (17.9%) received tranexamic acid (TXA), seven (25%) received both platelet transfusions and TXA, and seven (25%) received no treatment. Bleeding events requiring hospitalisation occurred in 20 (11.2%) patients. Bleeding was not predicted by presenting platelet count, TXA use, platelet transfusion or anticoagulant/antiplatelet therapies. Three patients died of bleeding, at varying platelet counts (18, 38 and 153 × 109 /L).

CONCLUSION

Thrombocytopenia is common in MDS. Although guidelines recommend otherwise, prophylactic platelet transfusions were commonly used for severe thrombocytopenia. Despite the majority of patients receiving platelet transfusions and/or TXA, 11% developed major bleeding occurring at a wide range of platelet counts.

Machine Learning Predicts 30-Day Outcome among Acute Myeloid Leukemia Patients: A Single-Center, Retrospective, Cohort Study

Acute myeloid leukemia (AML) is a clinical emergency requiring treatment and results in high 30-day (D30) mortality. In this study, the prediction of D30 survival was studied using a machine learning (ML) method. The total cohort consisted of 1700 survivors and 130 non-survivors at D30. Eight clinical and 42 laboratory variables were collected at the time of diagnosis by pathology. Among them, six variables were selected by a feature selection method: induction chemotherapy (CTx), hemorrhage, infection, C-reactive protein, blood urea nitrogen, and lactate dehydrogenase. Clinical and laboratory data were entered into the training model for D30 survival prediction, followed by testing. Among the tested ML algorithms, the decision tree (DT) algorithm showed higher accuracy, the highest sensitivity, and specificity values (95% CI) of 90.6% (0.918-0.951), 70.4% (0.885-0.924), and 92.1% (0.885-0.924), respectively. DT classified patients into eight specific groups with distinct features. Group 1 with CTx showed a favorable outcome with a survival rate of 97.8% (1469/1502). Group 6, with hemorrhage and the lowest fibrinogen level at diagnosis, showed the worst survival rate of 45.5% (25/55) and 20.5 days. Prediction of D30 survival among AML patients by classification of patients with DT showed distinct features that might support clinical decision-making.

Tranexamic acid for haemostasis and beyond: does dose matter?

Tranexamic acid (TXA) is a widely used antifibrinolytic agent that has been used since the 1960's to reduce blood loss in various conditions. TXA is a lysine analogue that competes for the lysine binding sites in plasminogen and tissue-type plasminogen activator impairing its interaction with the exposed lysine residues on the fibrin surface. The presence of TXA therefore, impairs the plasminogen and tPA engagement and subsequent plasmin generation on the fibrin surface, protecting fibrin clot from proteolytic degradation. However, critical lysine binding sites for plasmin(ogen) also exist on other proteins and on various cell-surface receptors allowing plasmin to exert potent effects on other targets that are unrelated to classical fibrinolysis, notably in relation to immunity and inflammation. Indeed, TXA was reported to significantly reduce post-surgical infection rates in patients after cardiac surgery unrelated to its haemostatic effects. This has provided an impetus to consider TXA in other indications beyond inhibition of fibrinolysis. While there is extensive literature on the optimal dosage of TXA to reduce bleeding rates and transfusion needs, it remains to be determined if these dosages also apply to blocking the non-canonical effects of plasmin.

4D intravital imaging studies identify platelets as the predominant cellular procoagulant surface in a mouse model of hemostasis

Interplay between platelets, coagulation/fibrinolytic factors, and endothelial cells (ECs) is necessary for effective hemostatic plug formation. This study describes a novel four-dimensional (4D) imaging platform to visualize and quantify hemostatic plug components with high spatiotemporal resolution. Fibrin accumulation following laser-induced endothelial ablation was observed at the EC-platelet plug interface, controlled by the antagonistic balance between fibrin generation and breakdown. Phosphatidylserine (PS) was first detected in close physical proximity to the fibrin ring, followed by exposure across the endothelium. Impaired PS exposure in cyclophilinD -/- mice resulted in a significant reduction in fibrin accumulation. Adoptive transfer and inhibitor studies demonstrated a key role for platelets, but not ECs, in fibrin generation during hemostatic plug formation. Inhibition of fibrinolysis with tranexamic acid (TXA) led to increased fibrin accumulation in WT mice, but not in cyclophilinD -/- mice or WT mice treated with antiplatelet drugs. These studies implicate platelets as the functionally dominant procoagulant surface during hemostatic plug formation. In addition, they suggest that impaired fibrin formation due to reduced platelet procoagulant activity is not reversed by TXA treatment.

Current advances in 2022: A critical review of selected topics by the Association for the Advancement of Blood and Biotherapies (AABB) Clinical Transfusion Medicine Committee

BACKGROUND

The Association for the Advancement of Blood and Biotherapies Clinical Transfusion Medicine Committee (CTMC) composes a summary of new and important advances in transfusion medicine (TM) on an annual basis. Since 2018, this has been assembled into a manuscript and published in Transfusion.

STUDY DESIGN AND METHODS

CTMC members selected original manuscripts relevant to TM that were published electronically and/or in print during calendar year 2022. Papers were selected based on perceived importance and/or originality. References for selected papers were made available to CTMC members to provide feedback. Members were also encouraged to identify papers that may have been omitted initially. They then worked in groups of two to three to write a summary for each new publication within their broader topic. Each topic summary was then reviewed and edited by two separate committee members. The final manuscript was assembled by the first and senior authors. While this review is extensive, it is not a systematic review and some publications considered important by readers may have been excluded.

RESULTS

For calendar year 2022, summaries of key publications were assembled for the following broader topics within TM: blood component therapy; infectious diseases, blood donor testing, and collections; patient blood management; immunohematology and genomics; hemostasis; hemoglobinopathies; apheresis and cell therapy; pediatrics; and health care disparities, diversity, equity, and inclusion.

DISCUSSION

This Committee Report reviews and summarizes important publications and advances in TM published during calendar year 2022, and maybe a useful educational tool.

Prophylaxis with low dose tranexamic acid in acute myeloid leukemia patients undergoing intensive chemotherapy

Patients suffering from acute myeloid leukemia (AML) carry a high risk of serious bleeding complications due to severe thrombocytopenia for long periods of time during treatment. Prior to prophylactic platelet transfusion becoming the standard of care, intracranial bleeding was a major contributor to death in AML patients. However, despite prophylactic platelet transfusions, up to 79% of patients with AML experience clinically significant bleeding during treatment. Antifibrinolytics are effective and well tolerated hemostatic agents widely used in many patient groups, and in this study, we investigated the effect of low dose tranexamic acid (TXA) in patients with AML and thrombocytopenia. We compared bleeding and thrombosis between 113 thrombocytopenic AML patients receiving TXA 500 mg three times daily (n = 36) versus no-TXA (n = 77). Clinical information was obtained systematically from electronic medical records, and laboratory data were collected from the laboratory information system. No difference was demonstrated in number of patients with at least one bleeding episode (TXA: 89% vs. no-TXA: 93%, p = 0.60), median number of bleeding days (TXA: 2.5 days vs. no-TXA 2.0 days, p = 0.30), bleeding location or transfusion needs between the two groups. However, platelet count was found to be a significant risk factor for bleeding, with a probability of bleeding of 35% with a platelet count below 5 × 109/L (logistic regression, p < 0.01). We found no difference in thromboembolic events between the two groups (TXA: 8% vs. no-TXA 10%, p = 0.99). In conclusion, treatment with low dose TXA is safe, but we found no evidence to suggest that it reduces bleeding in AML patients with thrombocytopenia.

Supportive Care for Patients With Myelodysplastic Syndromes

ABSTRACT

Myelodysplastic syndromes are a heterogeneous group of bone marrow disorders characterized by ineffective hematopoiesis, progressive cytopenias, and an innate capability of progressing to acute myeloid leukemia. The most common causes of morbidity and mortality are complications related to myelodysplastic syndromes rather than progression to acute myeloid leukemia. Although supportive care measures are applicable to all patients with myelodysplastic syndromes, they are especially essential in patients with lower-risk disease who have a better prognosis compared with their higher-risk counterparts and require longer-term monitoring of disease and treatment-related complications. In this review, we will address the most frequent complications and supportive care interventions used in patients with myelodysplastic syndromes, including transfusion support, management of iron overload, antimicrobial prophylaxis, important considerations in the era of COVID-19 (coronavirus infectious disease 2019), role of routine immunizations, and palliative care in the myelodysplastic syndrome population.

Absence of hyperfibrinolysis may explain lack of efficacy of tranexamic acid in hypoproliferative thrombocytopenia

The American Trial Using Tranexamic Acid (TXA) in Thrombocytopenia (A-TREAT, NCT02578901) demonstrated no superiority of TXA over placebo in preventing World Health Organization (WHO) grade 2 or higher bleeding in patients with severe thrombocytopenia requiring supportive platelet transfusion following myeloablative therapy for hematologic disorders. In this ancillary study, we sought to determine whether this clinical outcome could be explained on the basis of correlative assays of fibrinolysis. Plasma was collected from A-TREAT participants (n = 115) before the initiation of study drug (baseline) and when TXA was at steady-state trough concentration (follow-up). Global fibrinolysis was measured by 3 assays: euglobulin clot lysis time (ECLT), plasmin generation (PG), and tissue-type plasminogen activator (tPA)-challenged clot lysis time (tPA-CLT). TXA was quantified in follow-up samples by tandem mass spectrometry. Baseline samples did not demonstrate fibrinolytic activation by ECLT or tPA-CLT. Furthermore, neither ECLT nor levels of plasminogen activator inhibitor-1, tPA, plasminogen, alpha2-antiplasmin, or plasmin-antiplasmin complexes were associated with a greater risk of WHO grade 2+ bleeding. TXA trough concentrations were highly variable (range, 0.7-10 μg/mL) and did not correlate with bleeding severity, despite the fact that plasma TXA levels correlated strongly with pharmacodynamic assessments by PG (Spearman r, -0.78) and tPA-CLT (r, 0.74). We conclude that (1) no evidence of fibrinolytic activation was observed in these patients with thrombocytopenia, (2) trough TXA concentrations varied significantly between patients receiving the same dosing schedule, and (3) tPA-CLT and PG correlated well with TXA drug levels.

How I use platelet transfusions

Platelet transfusions are commonly administered for the prevention or treatment of bleeding in patients with acquired thrombocytopenia across a range of clinical contexts. Recent data, including randomized trials, have highlighted uncertainties in the risk-benefit balance of this therapy, which is the subject of this review. Hemovigilance systems report that platelets are the most frequently implicated component in transfusion reactions. There is considerable variation in platelet count increment after platelet transfusion, and limited evidence of efficacy for clinical outcomes, including prevention of bleeding. Bleeding events commonly occur despite the different policies for platelet transfusion prophylaxis. The underlying mechanisms of harm reported in randomized trials may be related to the role of platelets beyond hemostasis, including mediating inflammation. Research supports the implementation of a restrictive platelet transfusion policy. Research is needed to better understand the impact of platelet donation characteristics on outcomes, and to determine the optimal thresholds for platelet transfusion before invasive procedures or major surgery (eg, laparotomy). Platelet transfusion policies should move toward a risk-adapted approach that does not focus solely on platelet count.