Trial Title:
Are Uterine Fibroids Pro-thrombotic?
NCT ID:
NCT05607602
Condition:
Leiomyoma, Uterine
Thrombosis
Conditions: Official terms:
Leiomyoma
Myofibroma
Thrombosis
Study type:
Observational [Patient Registry]
Overall status:
Active, not recruiting
Study design:
Time perspective:
Prospective
Intervention:
Intervention type:
Other
Intervention name:
Comparison of blood samples between the two groups
Description:
In this study we will perform global haemostatic assays such as activated partial
thromboplastic time (APTT), and prothrombin time (PT). However, these tests provide
information about the haemostatic process until the point of initial fibrin formation and
ignore the procedure of thrombin generation[18]. In this study we will perform Thrombin
Generation studies, Plasma clot Lysis, and RNA sequencing in addition to standard
laboratory tests (APTT, PT, FVIII:C, fibrinogen (using Clauss methods), platelet count,
liver and renal function tests.
Arm group label:
1
Arm group label:
Group 2
Summary:
This study will investigate whether the presence of uterine fibroids is independently
associated with a laboratory defined pro-thrombotic phenotype. VTE is associated with
significant mortality and morbidity. In addition, treating patients with UF and
thrombosis represents a particular challenge as fibroids frequently cause menorrhagia,
which is exacerbated by anticoagulation. It is therefore important to recognise and
detect risk factors and prevent thrombosis wherever possible. If a pro-thrombotic
phenotype is detected in patients with UF as their sole risk factor, then this could
justify a new approach to the assessment and risk-management of a very large number of
patients and could translate into a reduction in both morbidity and mortality for
affected patients.
Detailed description:
Uterine Fibroids (UF) are benign uterine tumours, also known as leiomyomas. They are
estimated to affect up to 80% of women of reproductive age. UF more commonly occur in
women of Afro-Caribbean ethnicity. UF may be asymptomatic or associated with a range of
symptoms including menorrhagia, dysmenorrhea, sub-fertility, and pressure symptoms.
An association between Venous Thromboembolic disease and UF has been inferred in case
reports, series, and one population-based study. The true prevalence and the full scale
of the problem is unknown. As UF are so prevalent, in many women, the apparent
association reflects the presence of known risk factors for Venous Thromboembolism (VTE)
such as thrombophilia, smoking and significant co-morbidities such as cancer. Thrombosis
and UF have also been shown to have common risk factors, such as obesity and age.
Hormonal therapies, which are often used to treat the symptoms of UF, can also increase
the risk of VTE.
However, in a subset of women with VTE and UF, no thrombophilia or acquired risk factors
for VTE can be identified. In most of the reported case studies, bulky tumours cause
extrinsic compression of pelvic vessels, venous stasis and thus thrombosis. A clinical
case review reported by our centre has identified women with thrombosis and UF that do
not cause local venous stasis and no additional risk factors for thrombosis. This
suggests that there may be additional pathogenic mechanisms underlying the development of
thrombosis in individuals with UF. A second centre has also published a case review,
similarly identifying an apparent association between UF and thrombosis in the absence of
venous stasis.
Clot structure and function is dictated by the conditions present during fibrin
generation. Endogenous thrombin production, cellular components and fibrinogen structure
are all implicated in altering clot structure and function. There are several plausible
mechanisms via which UF may affect thrombin generation, clot formation and structure to
generate a pro-thrombotic state. The fibroid tumours may secrete Transforming Growth
Factor ß3 (TGF- ß3) and this appears to influence production of thrombomodulin,
antithrombin III and plasminogen activator inhibitor 1, all of which can modify the
blood's haemostatic capacity and may result in a pro-thrombotic phenotype.
Alternatively, fibroids may mediate an indirect pro-thrombotic effect by inducing iron
deficiency anaemia. Iron deficiency anaemia has been associated in numerous case studies
and series with thrombotic events, most commonly cerebral venous thrombosis, but also
Pulmonary Embolism (PE) and Deep Vein Thrombosis (DVT). Iron deficiency anaemia may also
cause a reactive elevation in erythropoietin thrombocytosis, thrombopoietin and FVIII
resulting in enhanced thrombin generation. In the proposed study we will exclude
participants with moderate and severe anaemia to identify whether any pro-thrombotic
phenotype identified is caused by a mechanism other than anaemia.
A pro-thrombotic phenotype can be identified by several laboratory studies that each
assess the quality and function of clots formed. In this study we will perform global
haemostatic assays such as activated partial thromboplastic time (APTT), and prothrombin
time (PT). However, these tests provide information about the haemostatic process until
the point of initial fibrin formation and ignore the procedure of thrombin generation. In
this study we will perform Thrombin Generation studies, Plasma clot Lysis, and RNA
sequencing in addition to standard laboratory tests (APTT, PT, FVIII:C, fibrinogen (using
Clauss methods), platelet count, liver and renal function tests.
2 METHODOLOGY Plasma clot lysis and thrombin generation studies will be carried out in
platelet poor plasma (PPP). Therefore, the part played by platelets and fibrinogen, it
will allow us to freeze and store the samples so that the tests can be done in batch once
all the samples have been collected. This allows for testing to be done homogenously
under the same conditions.
2.1 Plasma Clot lysis There is evidence that formation of compact clots, with increased
resistance to lysis, predisposes to thrombosis. A pro-thrombotic clot phenotype is
characterized by small pore size, low clot permeability, and increased resistance to
fibrinolysis. The plasma-based clot formation assay allows for a detailed assessment of
fibrin formation and breakdown capacity. The principle is that citrated, platelet-poor
plasma (PPP) is mixed with an activator of coagulation (recombinant tissue factor or
thrombin), as well as phospholipids and calcium to induce fibrin formation.
Simultaneously, tPa or another plasminogen activator is added to induce clot lysis. The
assay employs a turbidimetric principle, as the fibrin network is first formed and then
lysed in the well, turbidity increases and subsequently decreases. Absorbance is
registered continuously over a specified time period (e.g., 1.5 h), resulting in the
formation of the clot-lysis curve (Figure 1), from which the following parameters can be
derived: time to initial fibrin formation (lag phase), maximum absorbance (peak fibrin
concentration in well), integral or area under the clot lysis curve (AUC - net fibrin
formation), and time from peak to 50% lysis of the clot (50% lysis time).
Pro-thrombotic laboratory phenotypes detected by these assays have been associated with
unprovoked VTE, chronic thromboembolic pulmonary hypertension and post thrombotic
syndrome. It has been associated with recurrent PE and may be predictive of recurrent
DVT.
2.2 Thrombin Generation Thrombin generation is an established tool for assessing the
overall function of the blood clotting system. The whole clotting system is engaged in
the generation and subsequent inactivation of thrombin and the sum of these actions
results in either a haemostatic or a pro-thrombotic event. The method selected for
assessing thrombin generation is Calibrated Automated Thrombography (CAT) which involves
using a fluorescent substrate containing calcium to trigger thrombin generation, whilst
the software continuously monitors and records thrombin concentration in time. Using the
specialized software and calibrator, the fluorescent signal can be visualized as a
thrombogram. From this, parameters can be calculated such as lag time, time to peak
thrombin level, peak thrombin level, and endogenous thrombin potential (ETP).
2.3 RNA sequencing There is evidence in vitro and in vivo that extracellular RNA,
released upon vascular injury, promotes thrombosis by augmenting proteases involved in
the contact phase of coagulation. This theory was further demonstrated by Kannemeier et
al. (2007) who proved that the administration of RNAase delayed thrombus formation and
blood vessel occlusion. Extracellular RNA can be directly quantified by a method known as
RNA Sequencing. A more robust, reproducible, and easy-to-use technique has been developed
by NanoString Technologies, Inc. called "nCounter". Compared to routine RNA Sequencing,
nCounter can quantify smaller amounts of starting RNA (1ng vs. 100ng of total RNA).
Samples will be analysed in a NanoString Laboratory as nCounter is a proprietary
platform.
Criteria for eligibility:
Study pop:
Women aged 18 - 65 years with uterine fibroids confirmed on ultrasound able to provide
informed consent
Sampling method:
Non-Probability Sample
Criteria:
Inclusion Criteria:
Group 1: 35 patients with ultrasound confirmed uterine fibroids. Group 1a: 35 patients
with ultrasound confirmed uterine fibroids requiring myomectomy or hysterectomy.
Group 2: 35 control patients with a normal pelvis on ultrasound Able to provide informed
consent
Exclusion Criteria:• Personal history of thrombosis
- Pregnant
- Post- partum (within 6 weeks)
- Surgery within 90 days
- Family history of thrombosis (first degree relative)
- Co-morbidities: cancer, liver impairment, renal impairment, uncontrolled
hypertension
- Medication: Oral contraception containing oestrogen, hormone replacement therapy
with oral oestrogen, antiplatelet therapy, anticoagulation
- Tranexamic Acid within last 48hrs, Zoladex within the last 33 days
- Smoker
- If anaemia (Hb <110 g/L) is demonstrated on the study sample taken
Gender:
Female
Minimum age:
18 Years
Maximum age:
65 Years
Healthy volunteers:
Accepts Healthy Volunteers
Locations:
Facility:
Name:
King's College Hospital
Address:
City:
London
Zip:
SE5 9RS
Country:
United Kingdom
Start date:
October 17, 2022
Completion date:
December 31, 2024
Lead sponsor:
Agency:
King's College Hospital NHS Trust
Agency class:
Other
Collaborator:
Agency:
Hemab ApS
Agency class:
Industry
Source:
King's College Hospital NHS Trust
Record processing date:
ClinicalTrials.gov processed this data on November 12, 2024
Source: ClinicalTrials.gov page:
https://clinicaltrials.gov/ct2/show/NCT05607602
