Long-term Management of Homozygous Protein C Deficiency: Replacement Therapy with Subcutaneous Purified Protein C Concentrate

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.

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.

Use and Future Investigations of Recombinant and Plasma-Derived Coagulation and Anticoagulant Products in the Neonate

Although congenital bleeding disorders can manifest in the newborn period, the most common causes of bleeding and thrombosis in neonates are acquired conditions. Factor concentrates are used for specific diagnoses (hemophilia with inhibitors, specific factor deficiency, von Willebrand disease) and approved indications, and increasingly for off-label indications (bleeding in surgery cardiopulmonary bypass, extracorporeal membrane oxygenation). We will review the approved indications for factor products in the neonate and discuss the evidence and rationale for off-label use of factor products in management of bleeding and thrombosis in the neonate.

Efficacy and safety of protein C concentrate to treat purpura fulminans and thromboembolic events in severe congenital protein C deficiency

Severe congenital protein C (PC) deficiency (SCPCD) is associated with disseminated intravascular coagulation (DIC), purpura fulminans (PF), and vascular thromboembolic events (TE), often leading to organ failure and death. PC replacement therapy offers a safe, effective treatment for thromboembolic complications of SCPCD and secondary prophylaxis for recurrent DIC, PF, and TEs. A prospective, multi-centre, open-label, phase 2/3 study was conducted to demonstrate the safety and efficacy of protein C concentrate for treatment of PF and acute TEs. Fifteen enrolled patients with SCPCD received protein C concentrate; 11 received treatment for acute TEs (PF, 18 events; PF and other coumarin-related vascular thromboembolic events [coumarin-induced skin necrosis; CISN], 1 event; venous thrombosis, 5 events). Pre-defined efficacy criteria for treatment of acute TEs were compared with a historical control arm (i. e. patients receiving conventional therapy without protein C replacement). PF/CISN was demonstrated by pre-defined primary and secondary efficacy ratings. Primary ratings of protein C concentrate-treated episodes were significantly higher (p=0.0032) than in the historical control. For 19 PF/CISN episodes in 11 patients, 94.7 % of treatments were rated effective and 5.3 % effective with complications (not related to protein C concentrate). In a secondary efficacy rating, all treatments were rated effective (68.4 % excellent; 21.1 % good; 10.5 % fair). For 5/24 vascular thrombosis episodes, 80 % of treatments were rated excellent and 20 % were rated good. No treatment-related adverse events or serious adverse events occurred. In conclusion, protein C concentrate provides an efficacious, safe treatment for PF, CISN, and other TEs in SCPCD patients.

Long-term follow-up of homozygote protein C deficiency after multimodal therapy

Homozygous protein C deficiency is an extremely rare condition presenting in the neonatal period with purpura fulminans, with very high rates of morbidity and mortality. Optimal treatment for this condition is highly complex, poorly understood, and often limited by cost and product supply. We report a child who presented 2 days after birth with purpura fulminans and severe prenatal eye damage, but no cerebral lesions. He was treated with novel multimodal therapy culminating in liver transplant at 3 years of age. The patient is now 12 years of age, well, with blindness as his only long-term deficit.

Pediatric thrombophilia

Pediatric thrombosis and thrombophilia are increasingly recognized and studied. In this article, both the inherited and acquired factors for the development of thrombosis in neonates and children are categorized using the elements of Virchow's triad: stasis, hypercoagulable state, and vascular injury. The indications and rationale for performing thrombophilia testing are described. Also included are discussions on who, how, when, and why to test. Finally, recommendations for the use of contraceptives for adolescent females with a family history of thrombosis are outlined.

Diagnosis and management of neonatal purpura fulminans

Neonatal purpura fulminans is a rare, life-threatening condition, caused by congenital or acquired deficiencies of protein C or S. The condition is often fatal unless there is early recognition of the clinical symptoms, prompt diagnosis, and judicious replacement therapy is initiated. The clinical presentation is that of acute disseminated intravascular coagulation and hemorrhagic skin necrosis. The management includes an acute phase of replacement therapy with fresh frozen plasma or protein C concentrate and a maintenance therapy that includes anticoagulation with warfarin or low molecular weight heparin. This review focuses on the management of severe protein C deficiency.

Safety and pharmacokinetics of subcutaneously administered recombinant activated factor VII (rFVIIa)

BACKGROUND

 Recombinant activated factor VIIa (rFVIIa) is used to treat bleeds in hemophilia patients with inhibitors. A subcutaneous formulation could potentially improve its half-life and make it suitable for prophylactic treatment.

OBJECTIVES

 A study was conducted to determine the safety of subcutaneously administered rFVIIa in patients with hemophilia and the pharmacokinetic profile (including bioavailability).

PATIENTS/METHODS

 This was a multicenter, open-label, cross-over comparison of single doses of intravenous rFVIIa 90μgkg(-1) and a new formulation of rFVIIa for subcutaneous injection at dose levels of 45, 90, 180, 270 and 360μgkg(-1) . Sixty subjects (12 per dose cohort) with hemophilia A or B were enrolled.

RESULTS

 Subcutaneously administered rFVIIa showed lower mean peak plasma concentrations and prolonged FVII activity (C(max) , 0.44-5.16IU mL(-1) [across doses]; t(1/2) , 12.4h; t(max) , 5.6h) compared with intravenously administered rFVIIa (C(max) , 51.7IUmL(-1) ; t(1/2) , 2.7h; t(max) , <10min). The absolute bioavailability of subcutaneous rFVIIa ranged from 21.1 to 30.1% across dose levels. Dose proportionality was observed within a 2-fold dose increase but not across the full dose range. No thromboembolic events, drug-related serious adverse events, severe injection-site reactions or neutralizing antibodies were reported (primary endpoint). Mild and moderate injection-site reactions were more frequent with subcutaneous than with intravenous injections.

CONCLUSION

 This phase I clinical trial did not identify safety concerns of prolonged exposure to rFVIIa administered subcutaneously in single doses to hemophilia patients.

Long-term subcutaneous protein C replacement in neonatal severe protein C deficiency

We describe here the case of a boy who presented 2 days after birth with purpura fulminans on his feet and scalp. Laboratory investigations revealed signs of disseminated intravascular coagulation. An underlying coagulation disorder was suspected, and therapy with recombinant tissue plasminogen activator, fresh-frozen plasma, and unfractionated heparin was started. On the basis of plasma protein C activity and antigen levels of 0.02 and 0.03 IU/mL, respectively, after administration of fresh-frozen plasma, a diagnosis of severe protein C deficiency was established, and therapy with intravenous protein C concentrate (Ceprotin [Baxter, Deerfield, IL]) was started. Because of difficulties with venous access, we switched to subcutaneous administration after 6 weeks. The precise dosing schedule for subcutaneously administered protein C concentrate is unknown. In the literature, a trough level of protein C activity at >0.25 IU/mL is recommended to prevent recurrent thrombosis. During 1 year of follow-up our patient frequently had protein C activity levels at <0.25 IU/mL. Clinically, however, there was no recurrent thrombosis, and we kept the dosage unchanged. This report highlights 2 important points: (1) subcutaneously administered protein C concentrate is effective in treating severe protein C deficiency; and (2) in accordance with previous studies, after the acute phase trough levels of protein C activity at >0.25 IU/mL may not be necessary to prevent recurrent thrombosis. However, further research on the dosing, efficacy, and safety of protein C concentrate for prophylaxis and treatment of severe protein C deficiency is needed.

Long-term survival of a child with homozygous protein C deficiency successfully treated with living donor liver transplantation

Homozygous protein C deficiency is an autosomal recessive disorder often presenting with purpura fulminans. Fresh frozen plasma and oral anticoagulation have been used in the treatment of this disease. Lately, protein C concentrate has become the treatment of choice. However, protein C concentrate is not yet widely available in many countries. We report a six-month-old girl with homozygous protein C deficiency who had suffered from frequent thrombotic episodes. She was successfully treated with living donor liver transplantation. Eight years after the transplantation, she remains symptom free. As described here, the liver transplantation offers an alternative curative treatment for children with homozygous protein C deficiency.

Severe congenital protein C deficiency: description of a new mutation and prophylactic protein C therapy and in vivo pharmacokinetics

Severe congenital protein C deficiency is a rare life-threatening disorder that presents with purpura fulminans, disseminated intravascular coagulation, and thrombotic complications during the neonatal period. Affected children require acute replacement therapy with fresh frozen plasma or protein C concentrate, for example, Ceprotin (Baxter AG, Vienna). Long-term management and outcome is dependent on effective anticoagulation with warfarin, low-molecular weight heparin, or protein C concentrate. We describe the successful use of intravenous protein C concentrate for thrombotic prophylaxis in 2 sisters with severe type I protein C deficiency. Individualized long-term prophylactic regimens were developed based on clinical response. In vivo pharmacokinetic analyses of protein C concentrate were performed in each patient. Analysis of the protein C gene coding sequences identified 2 mutations in both patients, the previously described Arg169 to Trp mutation, and a novel mutation that changes Cys17 into a stop codon.

Coagulation factor concentrates: past, present, and future

Clotting factor transfusions are vital for people with diseases such as haemophilia. In the 1970s and 1980s, transfusions with pooled plasma led to a devastatingly high number of recipients becoming infected with blood-borne pathogens such as HIV and hepatitis C. This epidemic triggered the development of virus-free factor concentrates through a combination of improved donor selection and screening, effective virucidal technologies, and recombinant protein expression biotechnology. There is now a wide range of recombinant factor concentrates, and an impressive safety record with respect to pathogen transmission. However, remaining therapeutic challenges include the potential threat of transmission of prions and other pathogens, the formation of inhibitory alloantibodies, and the international disparity that exists in product availability due to differences in licensure status as well as prohibitively high costs. In the future, it is likely that bioengineered recombinant proteins that have been modified to enhance pharmacokinetic properties or reduce immunogenicity, or both, will be used increasingly in clinical practice.

Negative pressure dressing for promoting wound healing of purpura fulminans in a newborn with homozygous protein C deficiency

A negative pressure dressing to promote wound healing of purpura fulminans in a girl aged 35 days with homozygous protein C deficiency is reported. Two wounds of 11 x 11 cm2 at the abdominal wall and 14 x 14 cm2 at the left trunk were covered with sterile sponges embedded with a multiple-hole drain tube and transparent plastic film. The exposed end of the drain was then connected to the wall suction apparatus to create negative pressure at -120 mmHg. The dressing was changed every 2 days. Within 4-6 weeks, the wounds were completely healed and skin grafting was not required.

Modeling behavior of protein C during and after subcutaneous administration

Protein C is an important blood factor protein that regulates the blood coagulation process. Deficiency of protein C can lead to excessive coagulation that results in lack of tissue oxygenation, causing conditions such as deep vein thrombosis, pulmonary embolism, and stroke. Human protein C has been approved as a treatment for congenital protein C deficiency; however, the therapy requires frequent injections, due to the short residence time of the protein. Subcutaneous administration has been examined as an alternative to increase residence time and decrease injection frequency, thereby creating a more patient-friendly dosing regimen. In order to design an efficient injection or infusion protocol for subcutaneously administered proteins, it is important to accurately model the behavior (absorption, distribution, elimination) of these proteins in the body. However, several factors involved in a subcutaneous injection of the protein make modeling this behavior a challenging task. For example, absorption of the drug from the subcutaneous site into the blood stream can be variable depending on the site of injection, physical activity of the patient, etc. Furthermore, degradation of the protein can occur at the site of injection and further modify its absorption. The objective of this work was to demonstrate the utility of frequency response modeling as an alternative method to analyze the behavior of subcutaneously administered protein C. The results of our study indicate that if the dose range yielding the constant clearance of protein C is identified for the patient, models of that type, as presented in our study, can be used to adjust optimal dosing of protein C necessary to reach prescribed levels of the protein in this patient at desired time points, both specified by treatment requirements.

Subcutaneous administration of protein C concentrate

Children born with severe homozygous protein C deficiency do not survive beyond the neonatal period unless they receive protein C replacement. Protein C concentrate (Baxter Biosciences, Vienna) is usually given intravenously via a central venous catheter The authors describe 2 children in whom protein C concentrate was successfully administered by subcutaneous infusion after they had had recurrent central line infections. Alternate daily doses of 250-350 IU/kg resulted in trough protein C levels of > 25 IU/dL. In the follow-up period of 1-2 years neither child has had a thrombotic episode or purpuric skin lesions, and infusions are managed in the home by their parents.

Study of protein C, protein S, and antithrombin III in hypoxic newborns

OBJECTIVE

The aim of this study was to clarify the effect of hypoxia on the physiologic inhibition system of coagulation including protein S, protein C, and antithrombin III and to study their effect on thromboembolic accidents of hypoxic newborns.

DESIGN

Clinical study including ten hypoxic-ischemic neonates and ten normal neonates as a control group.

DATA SOURCES

MEDLINE, pediatric textbooks, neonatal intensive care unit, Department of Paediatrics, Faculty of Medicine, Cairo University.

RESULTS

The results of this study revealed a marked decrease in the level of the physiologic inhibition system of coagulation including antithrombin III, protein C, and protein S in 100% of the hypoxic-ischemic neonates compared with the control group (p <.001) before the occurrence of thromboembolic complications. Fifty percent of the hypoxic-ischemic neonates developed disseminated intravascular coagulation and died, 40% developed necrotizing enterocolitis and rectal bleeding, 20% developed hematuria, 30% developed hematemesis, 20% developed intracranial hemorrhage, and 100% had convulsions.

CONCLUSIONS

In this study, we evaluated the effect of asphyxia on the physiologic inhibition system of coagulation in neonates. Care providers should suspect hypoxia resulting from any obstructed labor and perform the necessary laboratory investigations for coagulation, including antithrombin III, protein C, and protein S levels, to help prevent thromboembolic accidents in asphyxiated neonates, including disseminated intravascular coagulation, necrotizing enterocolitis, and intracranial hemorrhage. Based on the development of antithrombin III and protein C concentrates, which are commercially available, require minimal monitoring, and have very few side effects, the time is ripe for evaluation of optimal treatment for thromboembolic accidents after neonatal asphyxia. This could be even more important if successful neuroprotectant strategies are also developed.

Chromatographic purification and properties of a therapeutic human protein C concentrate

Protein C deficiency (inherited and acquired) has a relatively high incidence rate in the general population worldwide. For many years, protein C deficient patients have been treated with fresh frozen plasma, prothrombin complex concentrates, heparin or oral anticoagulants, which all have clinical drawbacks. We report the production process of a highly purified human protein C concentrate from 1500 l of cryo-poor plasma by a four-step chromatographic procedure. After DEAE-Sephadex adsorption, protein C was separated from clotting factors II, VII and IX by DEAE-Sepharose FF and further purified, using a new strategy, by an on-line chromatographic system combining DMAE-Fractogel and heparin-Sepharose CL-6B. In addition, the product was treated against viral risks by solvent-detergent and nanofiltration on 15-nm membranes. The protein C concentrate was essentially free of other vitamin K-dependent proteins. Proteolytic activity was undetectable. Neither activated protein C, prekallikrein activator, nor activated vitamin K-dependent clotting factors were found resulting in good stability of the protein C activity. In vitro and in vivo animal tests did not reveal any sign of potential thrombogenicity. The final freeze-dried product had a mean protein C concentration of 58 IU/ml and a mean specific activity of 215 IU/mg protein, corresponding to over 12000-fold purification from plasma. Therefore, this concentrate appears to be of potential benefit for the treatment of protein C deficiency.

Heritable thrombophilia and childhood thrombosis

Thrombotic problems are rare during childhood but are increasingly recognized, particularly in tertiary care paediatric populations, and represent a different spectrum of disorders to those seen in adults. An understanding of the aetiological factors involved in the pathogenesis of these events is important both for prevention and management. A number of inherited prothrombotic defects have been shown to be independent risk factors for thromboembolism in adult studies, and may also contribute to thrombotic events in childhood. Homozygous deficiencies of naturally occurring inhibitors of coagulation are clearly associated with major prothrombotic disorders, often presenting in the perinatal period. The association of other inherited prothrombotic disorders with thrombosis in childhood is less well defined. The prevalence of heritable thrombophilia varies in different clinical settings and the risks associated with individual defects has only been addressed in a small number of studies to date. Additional acquired risk factors are also present in a high percentage of cases and again differ from those seen in adult thrombosis. Further studies are required to assess the risks associated with heritable thrombophilia during infancy and childhood, and to define the place of thrombophilia screening in paediatric practice.

Neonatal purpura fulminans due to homozygous protein C deficiency

Severe and recurrent purpura fulminans developed in a Turkish boy at 1 week of age. Initial coagulation studies performed were compatible with disseminated intravascular coagulation. Subsequent investigations showed that the patient had homozygous and his healthy parents had heterozygous protein C deficiency. The episodes of purpura fulminans were controlled by infusions of fresh frozen plasma and heparinization. Oral anticoagulant therapy was given in the symptom-free period.

Clinical management of protein C deficiency

Protein C (PC) is a vitamin K-dependent plasma protein that is structurally similar to other coagulation factors such as prothrombin and Factor X. PC is converted to its active anticoagulant form by a thrombin-thrombomodulin complex on the surface of capillary endothelial cells. Activated PC (APC) prevents the formation of blood clots by specifically inactivating factors Va and VIIIa in the clotting cascade. Both acquired and hereditary forms of PC deficiency exist, with hereditary further categorised as heterozygous, homozygous as well as doubly heterozygous. Patients suffering from symptomatic heterozygous PC deficiency present with purpura fulminans, venous thrombosis and/or pulmonary embolism. Homozygous PC deficiency is usually associated with the development of severe and often fatal, purpura fulminans and disseminated intravascular coagulation (DIC) during the neonatal period. Various therapeutic options have been described for long-term management of severe heterozygous and homozygous PC deficiencies. For the treatment of heterozygous PC deficiency, oral anticoagulation with a coumarin derivative or heparin therapy remains standard therapy. Homozygous patients may be treated with fresh frozen plasma (FFP) and iv. PC concentrate or coumarin derivatives. Other therapeutic options for the treatment of hereditary PC deficiency include the use of low-molecular weight heparin (LMWH), steroids and liver transplantation. Maintenance of a symptom-free life depends on response to therapy. Patients responding well to treatment can expect normalisation of haemostasis as well as improvement of microcirculation and resolution of purpura fulminans.

The molecular genetics of familial venous thrombosis

In the past few years, important advances have been made in the identification of factors predisposing to familial thrombophilia. Particular attention has been paid to the characterization of known inherited defects and their genotype-phenotype relationship, and to studying the interaction between single or multiple inherited conditions and acquired risk factors for venous thrombosis. The recent discovery of 'new' and very common genetic lesions predisposing to thrombosis has greatly expanded the interest in this field. Hereditary predisposition to venous thrombosis may be related to lesions in one or more of 10-15 genes encoding antithrombin, Protein C, Protein S, Factor V, prothrombin, enzymes of the homocysteine metabolic pathway, fibrinogen, heparin cofactor II, plasminogen and thrombomodulin. About 500 different gene lesions (substitutions, deletions, insertions) have so far been reported to affect these genes in patients with thrombotic disease. Because there are potentially multiple interactions between genetic and environmental factors, familial thrombophilia is now considered to be a multifactorial disease. The aim of this chapter is to review aspects of the molecular genetics of familial thrombophilia. In particular, those gene/protein defects for which there is convincing evidence of an association with familial thrombosis will be examined in detail.