Two Weeks of Low Molecular Weight Heparin for Isolated Symptomatic Distal Vein Thrombosis (TWISTER study)

BACKGROUND

Treatment of low-risk patients with isolated symptomatic distal deep vein thrombi (IDDVT) is uncertain.

OBJECTIVE

assess whether two weeks of therapeutic anticoagulation is efficacious/safe for IDDVT.

PRIMARY OUTCOME

symptomatic three-month venous thromboembolism (VTE) incidence in the two-week anticoagulation group. Secondary outcomes included post-thrombotic syndrome (PTS) and bleeding.

METHODS

Prospective multicentre cohort study. Consecutive low-risk IDDVT patients enrolled within 72 h of diagnosis and treated with therapeutic dose enoxaparin or rivaroxaban. At two weeks, patients had repeat complete whole leg compression ultrasound (CUS)/clinical review. If resolution of leg symptoms AND no radiological evidence of thrombus extension, anticoagulation was stopped. If ongoing symptoms and/or radiographic extension within distal veins, anticoagulation was continued for four more weeks. Patients with extension into the popliteal vein on two-week ultrasound were treated off-study. Patients were reviewed at three and six months.

FINDINGS/INTERPRETATION

241 eligible patients received ≥2 weeks anticoagulation. 167/241 (69%) were assigned to the 2-week anticoagulation group; 71/241 (30%) to the six-week anticoagulation group; 3/241 patients (1%) had extension into the popliteal vein on two-week CUS. Two patients in the two-week anticoagulation group had symptomatic IDDVT recurrence in ≤3 months; VTE recurrence 2/156; 1.3%(95% CI 0.05-4.85%). 69% of patients had complete resolution of symptoms within two weeks. Six-month PTS rates were 8/184, 4.4%(95% CI 2.1-8.5%). No major bleeding was reported. Our findings suggest it's safe/efficacious to stop therapeutic anticoagulation at two weeks in low-risk IDDVT patients with resolution of symptoms/no extension on ultrasound. This could replace 6-12 weeks of anticoagulation for ambulatory, low-risk IDDVT patients.

TRIAL REGISTRATION

ClinicalTrials.govNCT01252420.

A multi-centre, single-arm, open-label study evaluating the safety and efficacy of fixed dose rituximab in patients with refractory, relapsed or chronic idiopathic thrombocytopenic purpura (R-ITP1000 study)

The efficacy of a fixed-dose rituximab schedule was prospectively explored in primary/acute refractory, relapsed or chronic (platelet count >10 × 10(9) /l and ≤50 × 10(9) /l) idiopathic thrombocytopenic purpura (ITP). Patients received two doses of rituximab (1000 mg) on days 1 and 15 and were followed-up on weeks 1-8, 12, 26, 39 and 52. A total of 122 patients were included in the safety population; efficacy was analysed in 108 patients. Overall response rate (ORR) at week 8, defined as the proportion of patients achieving complete response (CR; platelet count >150 × 10(9) /l) or partial response (PR; platelet count >50 × 10(9) /l) was 44%. Therapeutic response, defined as achieving a response at week 8, with at least a minor response (MR; platelet count >30 × 10(9) /l), sustained up to weeks 26 and 52 and accompanied by a reduction in ITP medications, was achieved in 44% (week 26) and 35% (week 52) of patients, respectively. Treatment was well tolerated with no safety concerns. While this study failed to meet its primary endpoint of an ORR of 50%, the efficacy of two fixed doses of rituximab appear to provide similar efficacy to the standard 375 mg/m(2) four-dose schedule in relapsed/chronic ITP.

Platelet function and constituents of platelet rich plasma

Platelet Rich Plasma (PRP) therapies require blood to be processed prior to application, however, the full assessment of the output of platelet sequestration devices is lacking. In this study the products of the Autologous Fluid Concentrator (Circle BiologicsTM, Minneapolis, MN) and the Gravitational Platelet Separation System (GPS, Biomet, Warsaw, IN, USA) were evaluated in terms of platelet viability and PRP constituents. The AFC and GPS produced 6.4 (±1.0) ml and 6.3 (±0.4) ml of PRP, with platelet recovery of 46.4% (±14.7%) and 59.8% (±24.2%) producing fold increases of platelets of 4.19 (±1.62) and 5.19 (±1.62), respectively. Fibrinogen concentration was increased above baseline PPP produced with the AFC. pH was lower for both of the processed samples than for whole blood. White Blood Cell count was increased around 5 fold. Functional tests showed preserved viability with both devices. This represents essential knowledge that every treating physician should have before they can confidently administer PRP therapy produced by any method. These are the first published results of platelet function for the GPS system and the first performance results of the AFC system. The PRP produced is classified according to broad classifications as Leukocyte-PRP (L-PRP) for both devices.

Results of the APML3 trial incorporating all-trans-retinoic acid and idarubicin in both induction and consolidation as initial therapy for patients with acute promyelocytic leukemia

BACKGROUND

Initial therapy for patients with acute promyelocytic leukemia most often involves the combination of all-trans-retinoic acid with anthracycline-based chemotherapy. The role of non-anthracycline drugs in induction and consolidation is less well-established and varies widely between different cooperative group protocols.

DESIGN AND METHODS

In an attempt to minimize relapse and maximize survival for patients with newly diagnosed acute promyelocytic leukemia, the Australasian Leukaemia and Lymphoma Group utilized all-trans-retinoic acid and idarubicin as anti-leukemic therapy for both induction and consolidation. The protocol (known as APML3) was subsequently amended to incorporate maintenance with all-trans-retinoic acid, methotrexate and 6-mercaptopurine.

RESULTS

Eight (8%) of 101 patients died within 30 days, and 91 (90%) achieved complete remission. With a median estimated potential follow-up of 4.6 years, 4-year overall survival was 84%, and 71% of the patients remained in remission at 4 years. The cumulative incidence of all relapses was 28.1%, with 15 of the 25 relapses initially identified as an isolated molecular relapse. Both FLT3 mutations (internal tandem duplications and codon 835/836 kinase domain mutations) and increased white cell count at diagnosis were associated with inferior overall survival, but in multivariate analyses only FLT3 mutations remained significant (hazard ratio 6.647, P=0.005). Maintenance therapy was significantly associated with improved remission duration (hazard ratio 0.281, P<0.001) and disease-free survival (hazard ratio 0.290, P<0.001).

CONCLUSIONS

The combination of all-trans-retinoic acid and just two cycles of idarubicin followed by triple maintenance produced durable remissions in most patients, but patients with high-risk disease, especially those with FLT3 mutations, require additional agents or alternative treatment approaches. The significant reduction in relapse seen after the addition of maintenance to the protocol supports a role for maintenance in the context of relatively low chemotherapy exposure during consolidation. (actr.org.au identifier: ACTRN12607000410459).

Recommendations for the prevention of pregnancy-associated venous thromboembolism

Pregnancy is a risk factor for venous thromboembolism (VTE), an important cause of maternal morbidity and mortality. Although there is a 4-5-fold increased risk compared to that of nonpregnant women of the same age, the absolute risk is low at no more than two episodes of VTE per 1000 pregnancies. There is uncertainty about which women require thromboprophylaxis during pregnancy or postpartum because of a lack of data from appropriate clinical trials. For this reason, recommendations for prophylaxis should be made only after explaining the available evidence to the patient and taking into account her perception of the balance of risk and benefit in thromboprophylaxis. The aim of these recommendations is to provide clinicians with practical advice to assist in decisions regarding thromboprophylaxis in women considered to be at risk of VTE during pregnancy and the postpartum. The authors are clinicians from across New Zealand and Australia representing the fields of haematology, obstetric medicine, anaesthesiology, maternal-fetal medicine and obstetrics. Authors were invited to review the relevant literature and then worked collaboratively to devise recommendations and resolve areas of controversy. The recommendations contained herein were reached by consensus and represent the opinion of the panel. The absence of randomised clinical trials in this area limits the strength of evidence that can be used, and it is acknowledged that they represent level C evidence. The panel advocates for appropriate clinical studies to be carried out in this patient population to address the inadequacy of present evidence.

Isolated thrombocytopenia in children: thinking beyond idiopathic thrombocytopenic purpura and leukaemia

The commonest cause of isolated thrombocytopenia in an otherwise well child is idiopathic thrombocytopenic purpura (ITP). The inherited thrombocytopenias such as Bernard-Soulier syndrome are rare but often misdiagnosed as ITP owing to a similar clinical presentation. We describe a child with Bernard-Soulier syndrome who presented with isolated thrombocytopenia, mimicking ITP. Features which help to differentiate these two conditions are discussed with a brief literature review.

Platelet dysfunction in myelodysplastic syndromes: a clinicopathological study

Forty-eight patients with myelodysplastic syndromes and a platelet count greater than 80 x 10(9)/L were the subjects of a study of platelet function. A whole-blood platelet lumi-aggregometer was used for simultaneous measurement of platelet aggregation by the impedance method and of adenosine triphosphate-dense granule release. The results were correlated with skin bleeding time and episodes of clinical bleeding or thrombosis. Thirty-five patients had at least 1 abnormal result indicating platelet hypoactivity; 7 patients had mixed platelet hypoactivity and hyperactivity; and 4 patients had platelet hyperactivity. Only 2 patients had normal results. There was good correlation between platelet hypoactivity and prolonged skin bleeding time (P = .005); however, several patients with platelet hypoactivity had normal skin bleeding times. This finding suggested that whole-blood platelet aggregation studies may be more sensitive than bleeding time in identification of patients at risk of bleeding. Clinical hemorrhage was frequent (32 patients) in this cohort despite platelet counts greater than 100 x 10(9)/L. This finding indicated platelet hypofunction was clinically important. In contrast, only 2 of the 13 patients with thrombotic events had evidence of platelet hyperactivity, suggesting that other clinical factors are probably more important determinants of thrombosis. These observations confirm that platelet dysfunction is common in patients with myelodysplastic syndromes and suggest a useful role for routine whole-blood platelet aggregation studies to identify patients at risk of bleeding.

Effects of glycosylated recombinant human granulocyte colony-stimulating factor after high-dose cytarabine-based induction chemotherapy for adult acute myeloid leukaemia

The Australian Leukaemia Study Group (ALSG) investigated whether G-CSF would accelerate haemopoietic recovery after induction treatment for acute myeloid leukaemia (AML) intensified with high-dose cytarabine, and therefore improve response rates and survival. Patients were randomised to receive lenograstim (glycosylated recombinant human G-CSF) 5 microg per kg body weight subcutaneously daily from day 8 after starting chemotherapy, or no cytokine, following chemotherapy with cytarabine 3 g/m2 every 12 h on days 1, 3, 5, and 7, together with idarubicin 9 or 12 mg/m2 on days 1, 2, and 3, plus etoposide 75 mg/m2 on days 1 to 7 inclusive. Patients had untreated AML, and were aged 16 to 60 years. Overall, 54 evaluable patients were randomised to receive lenograstim and 58 to no cytokine. Patients in the lenograstim arm had a significantly shorter duration of neutropenia <0.5 x 10(9)/l compared to patients in the no cytokine arm (median 18 vs 22 days; P = 0.0005), and also shorter duration of total leucopenia <1.0 x 10(9)/l (17 vs 19 days; P = 0.0002), as well as a reduction in duration of treatment with therapeutic intravenous antibiotics (20 vs 24 days; P= 0.015) and a trend to reduced number of days with fever >38.0 degrees C (9 vs 12 days; P = 0.18). There were no differences between the two groups in platelet recovery, red cell or platelet transfusions, or non-haematological toxicities. For patients achieving CR after their first induction course, a reduction in the time to the start of the next course of therapy was observed in the lenograstim arm, from a median of 40.5 days to a median of 36 days (P = 0.082). The overall complete response rates to chemotherapy were similar, 81% in the lenograstim arm vs 75% for the no cytokine arm (P = 0.5), and there was no significant difference in the survival durations. We conclude that the granulopoietic stimulating effect of G-CSF is observed after induction therapy for AML intensified by high-dose cytarabine, resulting in an improvement in a number of clinically important parameters with no major adverse effects.

Impaired thrombin generation in beta 2-glycoprotein I null mice

Autoimmune antibodies to beta(2)-glycoprotein I (beta2GPI) have been proposed to be clinically relevant because of their strong association with thrombosis, miscarriage, and thrombocytopenia. By using a homologous recombination approach, beta2GPI-null mice were generated to begin to understand the physiologic and pathologic role of this prominent plasma protein in mammals. When beta2GPI heterozygotes on a 129/Sv/C57BL/6 mixed genetic background were intercrossed, only 8.9% of the resulting 336 offspring possessed both disrupted alleles. These data suggest that beta2GPI plays a beneficial role in implantation and/or fetal development in at least some mouse strains. Although those beta2GPI-null mice that were born appeared to be relatively normal anatomically and histologically, subsequent analysis revealed that they possessed an impaired in vitro ability to generate thrombin relative to wild type mice. Thus, beta2GPI also appears to play an important role in thrombin-mediated coagulation.

Thrombosis and bleeding in myeloproliferative disorders: identification of at-risk patients with whole blood platelet aggregation studies

Seventy-five patients with chronic myeloproliferative disorders were studied to investigate platelet function by simultaneous measurement of platelet aggregation by the impedance method and ATP dense granule release using a whole blood platelet lumi-aggregometer, in an attempt to identify patients at risk for thrombosis and bleeding. Thirty-nine patients had at least one abnormal result indicating platelet hyperactivity (i.e. impedance or release with one agonist being above the reference range); 16 patients had platelet hypoactivity (i.e. at least one result was below the reference range), whilst 14 had co-existence of hyper- and hypoactivity. Six patients had normal results. 20/53 patients with platelet hyperactivity (alone or mixed) had a positive history of venous and/or arterial thrombosis; in comparison, only two of the other 22 patients had a positive history. During a median follow-up of 33 months, nine patients with and one patient without platelet hyperactivity respectively developed new thrombotic events before the addition of specific therapy. A total of 50 patients with and eight patients without platelet hyperactivity respectively received specific treatment including aspirin and/or cytotoxic therapy. All but one elderly patient with platelet hyperactivity have remained free of new thrombotic events on specific therapy. Two of the 17 patients with platelet hypoactivity had major clinical bleeding. These observations highlight the need to test platelets for hyper- as well as hypo-function and suggest a useful role for routine whole blood platelet aggregation studies to identify the patients at risk for thrombosis or bleeding.

Plasma P-selectin is increased in thrombotic consumptive platelet disorders

P-selectin is a 140-kD protein found in the alpha-granules of platelets and the Weibel-Palade bodies of endothelial cells that on cell activation is expressed on the cell surface and also secreted into the plasma. The secreted form of P-selectin, like plasma P-selectin, differed from platelet membrane P-selectin in that its molecular mass was approximately 3 kD lower under reducing conditions. Both the secreted and plasma forms of P-selectin contained cytoplasmic sequence as determined by Western blot analysis with an affinity-purified rabbit anti-P-selectin cytoplasmic peptide antibody. We have measured plasma P-selectin and beta-thromboglobulin (beta TG) concurrently in (1) patients with consumptive thrombotic disorders, including disseminated intravascular coagulation (DIC), heparin-induced thrombocytopenia (HIT), and thrombotic thrombocytopenic purpura (TTP)/haemolytic uremic syndrome (HUS); (2) patients with idiopathic thrombocytopenic purpura (ITP); and (3) healthy controls. Patients with DIC, HIT, and TTP/HUS, but not ITP, had significantly elevated plasma P-selectin and beta TG levels when compared with their age-matched healthy controls. The increased plasma P-selectin and beta TG in patients with thrombotic disorders were likely to be the result of in vivo platelet and endothelial cell damage or activation. We also found that avoidance of veno-occlusion and other tedious measures customarily taken during blood collection and sample preparation to prevent in vitro platelet activation did not affect plasma P-selectin assay results. In addition, plasma P-selectin levels were not influenced by the presence of renal failure or heparin administration. These results indicate that plasma P-selectin may be a useful new marker for thrombotic diseases.