Management of severe congenital protein C deficiency with a direct oral anticoagulant, edoxaban: A case report

The clinical and genetic landscape of early-onset thrombophilia in Japan

OBJECTIVES

To determine the optimal management for early-onset thrombophilia (EOT), the genetic and clinical features of protein C (PC)-, protein S (PS)-, or antithrombin (AT)-deficient patients of ≤20 years of age were studied in Japan.

METHODS/RESULTS

Clinical and genetic information of all genetically diagnosed cases was collected through the prospective, retrospective study, and literature review. One-hundred-one patients had PC (n = 55), PS (n = 29), or AT deficiency (n = 18). One overlapping case had PC- and PS-monoallelic variant. Fifty-five PC-deficient patients (54%) had 26 monoallelic or 29 biallelic variant(s), and 29 (29%) PS-deficient patients had 20 monoallelic or nine biallelic variant(s). None of the patients had AT-biallelic variants. The frequent low-risk allele p.K193del (PC-Tottori) was found in five patients with monoallelic (19%) but not 29 with biallelic variant(s). The most common low-risk allele p.K196E (PS-Tokushima) was found in five with monoallelic (25%) and six with biallelic variant(s) (67%). One exceptional de novo PC variant was found in 32 families with EOT. Only five parents had a history of thromboembolism. Thrombosis concurrently developed in three mother-newborn pairs (two PC deficiency and one AT deficiency). The prospective cohort revealed the outcomes of 35 patients: three deaths with PC deficiency and 20 complication-free survivors. Neurological complications were more frequently found in patients with PC-biallelic variants than those with PC-, PS-, or AT-monoallelic variants (73% vs. 24%, p = .019).

CONCLUSIONS

We demonstrate the need for elective screening for EOT targeting PC deficiency in Japan. Early prenatal diagnosis of PC deficiency in mother-infant pairs may prevent perinatal thrombosis in them.

Pharmacokinetics of a microdosed cocktail of three direct oral anticoagulants in children with congenital heart defects: study protocol for a single-centre clinical trial (DOAC-Child)

INTRODUCTION

Direct oral anticoagulants (DOACs) are direct inhibitors of coagulation factor Xa and are frequently used in adults for different indications such as deep vein thrombosis or non-valvular atrial fibrillation. Paediatric patients might benefit as well from DOACs because the simplicity and convenience of their use is likely to decrease physical and psychological stress related to invasive procedures associated with phenprocoumon and heparin therapy. Thus, it is expected that the future use of DOACs will ultimately improve compliance and overall safety of anticoagulant therapies in paediatric populations. To assure safe and effective use the clinical pharmacology and pharmacokinetics (PK) of these drugs need to be evaluated in children.

METHODS AND ANALYSIS

This study is a single-centre, open-label, clinical trial in a paediatric population with non-cyanotic congenital heart defects. After having obtained informed consent from the parents, each participant will receive a single oral administration of a drinkable solution of a microdose cocktail of three FXa inhibitors consisting of apixaban (12.5 µg), rivaroxaban (12.5 µg), edoxaban (50 µg), plus a microdose of the two probe drugs midazolam (10 µg) and yohimbine (25 µg). Serial blood samples (n=up to 20) will be collected at specified time points before and up to 25 hours after cocktail administration. The primary PK endpoint will be the area under the plasma concentration time curve of apixaban, rivaroxaban and edoxaban. Secondary PK outcomes will be C_max, t_max, t_1/2, Cl/F and V_ss/F. Safety and tolerability of the microdose cocktail will be evaluated as well by a collection of adverse events.

ETHICS

This study has been approved by the responsible Ethics Committee of the Medical Faculty of Heidelberg University.

DISSEMINATION

Study results will be presented at international scientific meetings and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

EudraCT 2019-001759-38 16, DRKS00021455.

Diagnosis and management of severe congenital protein C deficiency (SCPCD): Communication from the SSC of the ISTH

Severe congenital protein C deficiency (SCPCD) is rare and there is currently substantial variation in the management of this condition. A joint project by three Scientific and Standardization Committees of the ISTH: Plasma Coagulation Inhibitors, Pediatric/Neonatal Thrombosis and Hemostasis, and Women's Health Issues in Thrombosis and Hemostasis, was developed to review the current evidence and help guide on diagnosis and management of SCPCD. We provide a summary of the clinical presentations, differential diagnoses, appropriate investigations to confirm the diagnosis, approaches for management of the acute situation, and options for long-term management including subsequent pregnancies. We finally provide a set of recommendations to help in this regard.

Inherited Thrombophilia in the Era of Direct Oral Anticoagulants

Severe inherited thrombophilia includes rare deficiencies of natural anticoagulants (antithrombin and proteins C and S) and homozygous or combined factor V Leiden and FII G20210A variants. They are associated with a high thrombosis risk and can impact the duration of anticoagulation therapy for patients with a venous thromboembolism (VTE) event. Therefore, it is important to diagnose thrombophilia and to use adapted anticoagulant therapy. The widespread use of direct anticoagulants (DOACs) for VTE has raised new issues concerning inherited thrombophilia. Concerning inherited thrombophilia diagnosis, DOACs are directed toward either FIIa or FXa and can therefore interfere with coagulation assays. This paper reports DOAC interference in several thrombophilia tests, including the assessment of antithrombin, protein S, and protein C activities. Antithrombin activity and clot-based assays used for proteins C and S can be overestimated, with a risk of missing a deficiency. The use of a device to remove DOACs should be considered to minimize the risk of false-negative results. The place of DOACs in the treatment of VTE in thrombophilia patients is also discussed. Available data are encouraging, but given the variability in thrombosis risk within natural anticoagulant deficiencies, evidence in patients with well-characterized thrombophilia would be useful.

Clinical and genetic features of Chinese pediatric patients with severe congenital protein C deficiency who first presented with purpura fulminans: A case series study and literature review

INTRODUCTION

Purpura fulminans (PF) is a hematological emergency that can be caused by severe congenital protein C (PC) deficiency. It has been rarely reported in the Chinese population. We aimed to characterize the clinical and genetic features of Chinese pediatric patients with severe congenital PC deficiency who first presented with PF.

MATERIALS AND METHODS

Twelve pediatric patients were diagnosed with severe congenital PC deficiency with PF, which was diagnosed based on our hospital records and previous reports from 1988 to July 2021 in China. We evaluated the clinical and genetic features of these patients.

RESULTS

Nine patients (9/12, 75%) had onsets that were observed within the first 48 h after birth. Six patients had a family history of thromboembolism. There was no consanguinity. Other symptoms were intracranial thrombosis or hemorrhage (4, 33.3%), ocular lesions (2, 16.7%), gastrointestinal hemorrhage (2, 16.7%) and kidney infarction before birth (1, 8.3%). All but one of the patients (one case not detected) had a plasma PC activity of <10%. The genetic study indicated that in the eight patients with inherited PC deficiency, two were homozygous, five were compound heterozygous and one was heterozygous for PC deficiency.

CONCLUSION

This is the first and largest case series of Chinese pediatric patients with severe congenital PC deficiency who first presented with PF. It has been shown that treatment with both fresh frozen plasma and anticoagulants is recommended when PC concentrate is not easily available, especially in developing countries.

Clinical Impact of Heritable Thrombophilia on Neonatal-Onset Thromboembolism: A Nationwide Study in Japan

OBJECTIVE

To clarify the incidence and genetic risk of neonatal-thromboembolism, we conducted a nationwide study exploring the impact of thrombophilia on neonatal-thromboembolism in Japan.

STUDY DESIGN

A questionnaire survey was conducted for perinatal centers in Japan, focusing on the clinical expression, genotype, treatment, and outcome of patients who developed thromboembolism within 28 days of birth from 2014 to 2018.

RESULTS

The estimated incidence of neonatal-thromboembolism was 0.39 cases per 10 000 live births. Intracranial lesions and purpura fulminans occurred in 66 and 5 of 77 patients, respectively. Fifty-eight (75.3%) infants presented within 3 days after birth. Four (5.2%) died, and 14 (18.2%) survived with disability. At the diagnosis, <20% plasma activity of protein C was noted in 16 infants, protein S (in 2), and antithrombin (in 1). Thirteen genetic tests identified 4 biallelic and 5 monoallelic protein C-variants but no protein S- or antithrombin-variants. Protein C-variants had purpura fulminans (P < .01), ocular bleeding (P < .01), positive-family history (P = .01), and death or disability (P = .03) more frequently than others. Protein C-variants were independently associated with disability (OR 5.74, 95% CI 1.16-28.4, P = .03) but not death. Four biallelic variants had serious thrombotic complications of neurologic disability, blindness, and/or amputation. Three monoallelic variants survived without complications. The only protein C-variant death was an extremely preterm heterozygote infant.

CONCLUSIONS

Monoallelic protein C-variants had a higher incidence of neonatal-thromboembolism than biallelic variants. Thrombophilia genetic testing should be performed in the setting of neonatal-thromboembolism and low protein C to identify the underlying genetic defect.

Multiple arterial and venous thromboembolism in a male patient with hereditary protein C deficiency: A case report

RATIONALE

Hereditary protein C deficiency has a high prevalence in Asian populations, being the important risk factor associated with thrombophilia. Traditionally, conservative medication is the first choice for patients with hereditary protein C deficiency. However, there are few reports on whether aggressive surgical treatment can be performed when patients continue to develop life-threatening ischemic symptoms after adequate anticoagulant and thrombolytic therapy.

PATIENT CONCERNS

A 40-year-old male presented with right lower extremity pain for 1 week.

DIAGNOSIS

Computed tomography angiography (CTA) of lower extremity indicated arterial embolization of the right superficial femoral artery. Vascular ultrasonography showed old extensive thrombus in the deep vein of the left lower extremity. Electrocardiogram reported old anterior myocardial infarction. Sequencing of the gene encoding protein C (PROC) gene revealed that a heterozygous in-frame deletion mutation (c.577-579delAAG, p.192delK). Based on these findings, the diagnosis of hereditary protein C deficiency was made.

INTERVENTIONS

The patient was given low-molecular-weight heparin (LMWH) anticoagulation and urokinase treatment immediately. Then we performed the Fogarty catheter embolectomy with about 18.5 cm thrombus being removed and utilized the balloon catheter to dilate the anterior tibial artery. Despite given adequate anticoagulant and thrombolytic therapy postoperatively, the patient still had new thrombosis, and eventually underwent arterial embolectomy and amputation.

OUTCOMES

The patient was discharged with good wound healing and continued rivaroxaban treatment at a dose of 20 mg daily. The patient was followed-up monthly until 1 year: there was no adverse ischemic events occurred.

LESSONS

Aggressive surgical treatment may be the effective attempt for life-saving when conservative treatment as the first choice had unsatisfactory results in hereditary protein C deficiency patients. The novel oral anticoagulants (NOACs) could be more suitable than warfarin for the treatment and prevention of recurrence in patients with hereditary protein C deficiency.

Case Report: Successful Long-Term Management of a Low-Birth Weight Preterm Infant With Compound Heterozygous Protein C Deficiency With Subcutaneous Protein C Concentrate Up to Adolescence

Homozygous/compound heterozygous forms of congenital protein C deficiency are often associated with severe antenatal and postnatal thrombotic or hemorrhagic complications. Protein C deficiency frequently leads to severe adverse outcomes like blindness and neurodevelopmental delay in children and may even lead to death. The most widely used long-term postnatal treatment consists of oral anticoagulation with vitamin K antagonists (e.g., warfarin), which is supplemented with protein C concentrate in acute phases. Subcutaneous infusions have been described in infants mostly from 2 months of age after severe postnatal thrombosis, but not in newborns or premature infants without thromboembolism. We report the first case of a compound heterozygous protein C-deficient preterm infant, born at 31+5 weeks of gestation to parents with heterozygous protein C deficiency (protein C activity 0.9% at birth). We focus on both prenatal and perinatal management including antithrombotic treatment during pregnancy, the cesarean section, and continuous postnatal intravenous and consecutive subcutaneous therapy with protein C concentrate followed by a change of therapy to direct oral anticoagulants (DOACs) (apixaban). We report successful home treatment with subcutaneous protein C concentrate substitution overnight (target protein C activity >25%) without complication up to 12.5 years of age. We propose that early planned cesarean section at 32 or preferably 34 weeks of gestation limits potential maternal side effects of anticoagulation with vitamin K antagonists and reduces fetal thromboembolic complications during late pregnancy. Intravenously administered protein C and early switch to subcutaneous infusions (reaching about 3 kg body weight) resulted in sufficient protein C activity and has guaranteed an excellent quality of life without any history of thrombosis for 13 years now. In older children with protein C deficiency, as in our case, DOACs could be a new therapeutic option.

Recurrent Cerebral Venous Thrombosis Treated with Direct Oral Anticoagulants in a Japanese Man with Hereditary Protein C Deficiency

We herein report a case involving a 32-year-old Japanese man with recurrent cerebral venous thrombosis due to hereditary protein C deficiency. He was admitted to our hospital with impaired consciousness. Brain magnetic resonance imaging demonstrated high intensities diffusely along the bilateral sulci and magnetic resonance venography revealed left transverse sinus and superior sagittal sinus stenoses. His father had a history of cerebral infarction and venous thrombosis. The protein C activity level examined by chromogenic synthetic substrate assay was markedly reduced. He was diagnosed with protein C deficiency, and a genetic analysis revealed a heterozygous mutation at exon 3 c.199G>A,p.Glu67Lys on the protein C gene. Four months later, at his second admission, he had transient aphasia, and his protein C activity was under 10%. We switched warfarin to the direct oral anticoagulants edoxaban. He remains fully recovered with no adverse events after the administration of edoxaban for a year. Direct oral anticoagulants may be a new tool for treating cerebral venous thrombosis due to hereditary protein C deficiency.

Direct oral anticoagulants in patients with severe inherited thrombophilia: a single-center cohort study

We investigated the safety and efficacy of direct oral anticoagulants (DOACs) in patients with venous thromboembolism (VTE) associated with severe inherited thrombophilia. In this single-center cohort study, we enrolled 56 consecutive VTE patients with severe inherited thrombophilia, defined as the presence of antithrombin (n = 18), protein C (n = 12) and protein S (n = 12) deficiencies, homozygous Factor V Leiden (n = 3) and prothrombin G20210AA (n = 4) mutations, or combined defects (n = 7). During a median follow-up of 44.5 (IQR 30-52.5) months, rivaroxaban was used in 30 (53.6%), apixabanin 14 (25%), and dabigatran in 12 (21.4%) subjects. Recurrent nonfatal VTE was observed in 5 (8.9%) patients (2.4 per 100 patient-years), treated with rivaroxaban (n = 4) and apixaban (n = 1). Major bleeding and clinically relevant non-major bleeding (CRNMB) occurred in 2 (3.5%) and 4 (7%) subjects, respectively (0.96 per 100 patient-years and 1.92 per 100 patient-years, respectively), including 4 patients on rivaroxaban. The event-free survival analysis showed that the use of rivaroxaban was associated with increased risk of recurrent VTE or bleeding, compared with apixaban or dabigatran (HR 2.76, 95% CI 1.26-3.92, p = 0.039). In conclusion, the results of our cohort study indicate that full-dose dabigatran or apixaban are effective and safe in patients with severe inherited thrombophilia.

Differential effects of direct factor IIa and factor Xa inhibitors in protein C-deficient plasma detected using thrombin generation and viscoelastometry assays

INTRODUCTION

Protein C (PC) deficiency results in dysregulated thrombin generation and increases thrombosis risk.

METHODS

In order to investigate the potential effects of anticoagulant drugs in PC deficiency, we evaluated the pharmacodynamic effect of selective direct factor (F) IIa inhibitors (dabigatran and argatroban), selective direct FXa inhibitors (rivaroxaban and apixaban) and an indirect FXa/FIIa inhibitor (enoxaparin) in commercial PC-deficient plasma using thrombin generation and viscoelastometry assays modified to reflect PC anticoagulant activity.

RESULTS

Endogenous thrombin potential (ETP) and peak thrombin concentration (PTC) were increased in PC-deficient plasma but this corrected completely with PC concentrate. Inhibition of FIIa and FXa with the selective inhibitors also corrected the increased ETP and PTC but required high drug concentrations. There was sustained low-level thrombin generation in PC-deficient plasma with FXa inhibitors but not with FIIa inhibitors. Adding PC concentrate to PC-deficient plasma anticoagulated with dabigatran had little additional effect on ETP or PTC. In contrast, addition of even small quantities of PC concentrate to PC-deficient plasma anticoagulated with rivaroxaban further diminished ETP, primarily by abolishing sustained thrombin generation. In the viscoelastometry assay, the coagulation time was shortened and α-angle increased in PC-deficient plasma. These abnormalities reversed with both dabigatran and rivaroxaban.

CONCLUSION

The selective direct FXa and FIIa inhibitors at high concentrations both counteracted the abnormal thrombin generation and clot formation observed in PC-deficient plasma, but with qualitative differences in their effects.