Current therapy for rare factor deficiencies

[How to interpret and pursue a prolonged quick time or APTT]

The standard hemostasis workup [quick time (QT), and activated partial thrombin time (APTT)] is very commonly prescribed but its interpretation is often difficult for practitioners who are not specialized in hemostasis. Here, we review the principles of the diagnostic approach to these tests. Only a very basic knowledge of the coagulation cascade is necessary to identify which clotting factor tests to prescribe and to interpret the results. Deficiency in several clotting factors suggests liver dysfunction, disseminated intravascular coagulation (DIC) or vitamin K deficiency. If a single factor is deficient, we review the different causes of acquired deficiencies and briefly discuss the characteristics of the different congenital defects, which generally require specialized management. Lupus anticoagulant is a common and generally benign cause of prolonged APTT to be aware of, which is not related to a hemorrhagic risk. A good knowledge of the diagnostic approach to abnormal QT or APTT generally allows the resolution of the most common situations.

Clinical, Laboratory, and Molecular Aspects of Factor V Deficiency

Factor V (FV) is a glycoprotein that plays a pivotal role in hemostasis, being involved in coagulant and anticoagulant pathways. Congenital FV deficiency is a rare bleeding disorder with an incidence of 1 per million live births, considering the most severe homozygous form. FV deficiency is diagnosed using routine coagulation tests and FV activity assays. Several mutations, including missense, nonsense, and frameshift, have been detected in the F5 gene. Clinical symptoms are variable, ranging from mild ecchymoses and mucosal bleeding to life-threatening intracranial hemorrhage. The mainstay of treatment includes fresh-frozen plasma, preferentially virus-inactivated. In this narrative review, we provide an update of the main laboratory, molecular, clinical, and therapeutic features of inherited FV deficiency.

Rare Coagulation Factor Deficiencies (Factors VII, X, V, and II)

Although rare clotting factor deficiencies primarily referred to as rare bleeding disorders (RBD), including factors II, V, VII, and X, make up ∼5% of all inherited bleeding disorders worldwide, each of these clotting factors play a critical role in the coagulation cascade. Incomplete bleeding evaluation or misinterpretation of laboratory studies can result in delayed diagnoses that ultimately affect patient outcomes. Bleeding manifestations can range from mild to severe, but the most common are mucocutaneous bleeding. The ideal treatment in RBD is dedicated single-factor concentrates that can be used for acute bleeding events, surgical management, and prophylaxis.

Pharmacokinetics, surrogate efficacy and safety evaluations of a new human plasma-derived fibrinogen concentrate (FIB Grifols) in adult patients with congenital afibrinogenemia

BACKGROUND AND AIMS

Congenital afibrinogenemia is a rare coagulation disorder resulting from a deficiency in fibrinogen. This study assessed the pharmacokinetics, surrogate efficacy and safety of FIB Grifols, a new human plasma-derived fibrinogen concentrate, to treat congenital afibrinogenemia.

METHODS

Eleven adult patients from a multinational, phase 1-2, prospective, open-label, single-arm, uncontrolled clinical study received a single infusion of FIB Grifols, 70 mg/kg bw. Fibrinogen pharmacokinetics (fibrinogen activity: Clauss method; antigen plasma concentrations: ELISA) and efficacy parameters were determined over 14 days after infusion. Efficacy endpoints were the mean change on plasma maximum clot firmness (MCF) on viscoelastic testing and coagulation tests 1-hour post-infusion, and correlation with fibrinogen levels throughout. Safety parameters were also assessed.

RESULTS

For the Clauss method, (mean [standard deviation]) baseline adjusted C_max was 1.99 (0.40) g/L, reached 1.76 (1.00) h after infusion, and half-life was 76.94 (20.21) h. Using ELISA, C_max after FIB Grifols infusion was 2.88 (0.86) mg/mL, with a t_max of 3.06 (2.24) h. Fibrinogen activity and antigen concentrations showed statistically significant correlation of 0.9120 (P < 0.001). Surrogate efficacy was demonstrated by a significant increase of 12.35 (3.85) mm in MCF. Prothrombin time, activated partial thromboplastin time and thrombin time, returned to normal ranges over time, indicating restoration of functionally active fibrinogen. There were no treatment-related adverse events, allergic reactions, serious adverse events, or discontinuations.

CONCLUSIONS

The pharmacokinetic profile of functionally active FIB Grifols was established, hemostasis was restored, and FIB Grifols was safe and well tolerated in fibrinogen-deficient patients.

Pharmacological management of rare coagulation factor deficiencies besides hemophilia

INTRODUCTION

Rare coagulation factor deficiencies are less-known disorders with variable effects on the patient's life. Management of such patients is a challenge due to the paucity of evidence-based data, more so when patients with these rare disorders encounter a more rare, related condition, like inhibitor development or thrombosis.

AREA COVERED

A comprehensive literature search related to RCFDs and management was performed in PubMed in order to discuss therapeutic options and challenges, prophylaxis, management of minor and major surgeries, obstetric and gynecological complications, inhibitor development, and thrombosis.

EXPERT OPINION

Although significant changes have occurred in the management of RCFDs in recent years, more evidence-based studies besides expert opinion are needed for optimal management.

Successful hemostatic management of major surgery for cervical spondylotic myelopathy in a patient with severe factor XI deficiency

Factor XI deficiency (FXID) is a rare bleeding disorder caused by mutations in the F11 gene. Spontaneous bleeding in patients with factor XI deficiency is rare, but major bleeding may occur after surgery or trauma. The basic method for hemostatic treatment is replacement of the missing factor using FXI concentrate or fresh frozen plasma (FFP). We report the case of a 72-year-old male with severe FXID who underwent a laminoplasty under sufficient, but minimal, FFP transfusion. Through detailed monitoring of activated partial thromboplastin time (APTT) and FXI activity at the perioperative period, we succeeded in hemostatic management of major surgery without significant blood loss and fluid overload. From the course of this case, we found that measuring FXI activity is superior to measuring APTT. Furthermore, we identified a novel homozygous mutation in F11 [NM_000128.3:c.1041C > A:p.(Tyr347*)] by whole exome sequencing.

Inherited factor II deficiency with paradoxical hypercoagulability: a case report

: Congenital deficiency of factor II is a very rare autosomal recessive disorder that can result in a bleeding diathesis. Genotypically, individuals are either homozygous for a defective prothrombin gene or a compound heterozygote with different mutated prothrombin genes inherited from each parent. Phenotypically, it is characterized by either a low production of normal prothrombin or a near-normal production of dysfunctional prothrombin. Treatment is aimed at restoring normally functioning factor II circulating levels to sufficient concentration for hemostasis. Paradoxical thrombosis in patients born from a nonconsanguineous marriage with factor II deficiency has not been reported. A woman with known congenital factor II deficiency confirmed by history and hemostatic laboratory analysis presented with an unprovoked spontaneous thrombosis of the common femoral vein detected on color Doppler. Venous thrombosis can occur in congenital deficiency of factor II and inferior vena cava filter can be life-saving.

Diagnosis and Treatment of von Willebrand Disease and Rare Bleeding Disorders

Along with haemophilia A and B, von Willebrand disease (VWD) and rare bleeding disorders (RBDs) cover all inherited bleeding disorders of coagulation. Bleeding tendency, which can range from extremely severe to mild, is the common symptom. VWD, due to a deficiency and/or abnormality of von Willebrand factor (VWF), represents the most frequent bleeding disorder, mostly inherited as an autosomal dominant trait. The diagnosis may be difficult, based on a bleeding history and different diagnostic assays, which evaluate the pleiotropic functions of VWF. Different treatment options are available for optimal management of bleeding and their prevention, and long-term outcomes are generally good. RBDs are autosomal recessive disorders caused by a deficiency of any other clotting factor, apart from factor XII, and cover roughly 5% of all bleeding disorders. The prevalence of the severe forms can range from 1 case in 500,000 up to 1 in 2–3 million, according to the defect. Diagnosis is based on bleeding history, coagulation screening tests and specific factor assays. A crucial problem in RBDs diagnosis is represented by the non-linear relationship between clinical bleeding severity and residual clotting levels; genetic diagnosis may help in understanding the phenotype. Replacement therapies are differently available for patients with RBDs, allowing the successful treatment of the vast majority of bleeding symptoms.

Hereditary Blood Coagulation Disorders: Management and Dental Treatment

Patients with hereditary hemostatic disorders, characterized by a tendency to bleeding or thrombosis, constitute a serious challenge in the dental practice. Advances in the medical diagnosis of hemostatic disorders have exposed dental professionals to new patients not amenable to the application of the management protocols associated with other, more well-known, disorders. It is the aim of this paper to review the evidence, to highlight the areas of major concern, and to suggest management regimens for patients with hereditary hemostatic disorders. An extensive review has been made (PubMed, Science Direct, Web of Knowledge, etc.) of literature pertaining to hereditary disorders affecting blood coagulation factors and how they affect the practice of dentistry. Several aspects relating to the care of such patients must be recognized and taken into consideration when dental treatment is planned. Replacement of deficient coagulation factors ensures that safe dental treatment will be carried out. However, the half-life of such coagulation factors requires that dental treatment be specifically planned and adapted to the type of pathology involved.

Preclinical Safety and Pharmacokinetics of Recombinant Human Factor XIII

Factor XIII (FXIII) is a thrombin-activated protransglutaminase responsible for fibrin clot stabilization and longevity. Deficiency in FXIII is associated with diffuse bleeding and wound-healing disorders in humans. This report summarizes results from several studies conducted in adult cynomolgus monkeys ( M. fascicularis) to evaluate the safety and pharmacokinetics of recombinant human factor XIII A2 dimer (rFXIII). Intravenous slow bolus injection of rFXIII resulted in the expected formation of the heterotetramer rA2cnB2, prolonged circulating half-life (5–7 days), and increased plasma transglutaminase activity. Recombinant FXIII was well tolerated as a single dose up to 20 mg/kg rFXIII (2840 U/kg), as repeated daily doses up to 6 mg/kg (852 U/kg) for 14 days, and as 3 repeated doses of 8 mg/kg (1136 U/kg) separated by 14 days. Overt toxicity occurred after a single intravenous injection of ≥ 22.5 mg/kg rFXIII (3150 U/kg), or with 2 doses of =12.5 mg/kg (1775 U/kg) administered within 72 hours. The rFXIII-mediated toxicity was expressed as an acute systemic occlusive coagulopathy. Evaluation of plasma samples from dosed animals demonstrated formation of cross-linked fibrin/fibrinogen oligomers and higher-order protein aggregates, which are hypothesized to be responsible for the observed vessel occlusion and associated embolic sequelae. These results demonstrate that rFXIII-mediated toxicity results from exaggerated pharmacological activity of the molecule at supraphysiological concentrations. The absence of observed toxicological effect with repeated intravenous doses up to 8 mg/kg (1136 U/kg) was used to support an initial clinical dose range of 0.014 to 0.35 mg/kg (2–50 U/kg).

Transfusion management of factor V deficiency: three case reports and review of the literature

BACKGROUND

Factor V (FV) deficiency may be inherited as an autosomal recessive disease or acquired as a result of autoantibody formation, either spontaneously or secondary to exposure to bovine thrombin or medications. Congenital FV deficiency has traditionally been treated with plasma transfusions. However, recent evidence has suggested that platelet (PLT) transfusions may be a better alternative as FV stored within PLT alpha granules has greater procoagulant potential and is released locally at sites of vascular injury. We report three cases of FV deficiency, one congenital and two acquired, and emphasize the different management approaches.

CASE REPORTS

Patient 1 was a 30-year-old man with congenital FV deficiency who presented with a trauma-induced hematoma of his lower extremity. He was treated with 5 PLT units over 48 hours. Patient 2 was a 64-year-old woman who presented with an upper-extremity thrombus and was discovered to have a FV inhibitor, likely secondary to antibiotics. Patient 3 was a 75-year-old woman with hepatitis C virus (HCV) who presented with minor ecchymosis and was found to have a FV inhibitor secondary to either HCV or antibiotic exposure. Corticosteroids alone were able to eradicate the inhibitors in both patients with acquired inhibitors.

CONCLUSIONS

FV deficiency can present with a diverse range of symptoms. For bleeding patients, PLT transfusions should be the initial therapy. In patients with thrombosis, the risks and benefits of anticoagulation must be carefully assessed before treatment. For patients with minor bleeds, transfusions may be withheld, and elimination of the inhibitor should be the primary objective.

A case of pregnancy complicated with congenital dysprothrombinemia (prothrombin Tokushima)

We present the course of pregnancy and delivery in a patient with congenital dysprothrombinemia. The patient is a 29-year-old nulliparous woman. She was diagnosed with dysprothrombinemia at 10 years of ag. Her course of pregnancy was uneventful. She delivered after prophylactic lyophilized human blood coagulation factor IX complex 800 U was administered. The plasma prothrombin activity was at 24.0% of normal plasma clotting activity. Her postpartum course was uneventful. After 6 years, her course of pregnancy was the same as before. Prophylactic lyophilized human blood coagulation factor IX complex 800 U was administered. Her plasma prothrombin activity was at 26.7%, and she underwent an induced delivery. Her postpartum course was uneventful. It is beneficial to use prophylactic lyophilized human blood coagulation factor IX complex 800 U in pregnancies that are complicated by dysprothrombinemia. The goal of therapy is to maintain prothrombin levels at above 20%.

Rare bleeding disorders: diagnosis and treatment

Despite the worldwide prevalence of rare bleeding disorders (RBDs), knowledge of these conditions and their management is suboptimal; health care professionals often have little diagnostic and treatment experience with variable access to diagnostic modalities required for accurate identification. Therefore, patients often experience morbidity and mortality due to delayed diagnosis. As RBDs represent a small potential commercial market, few, if any, specific therapies exist for these conditions. As a result, affected individuals commonly face delayed diagnosis, incomplete laboratory evaluation, and limited treatment options. Standardization and customization of coagulation assays, full genome sequencing, and global clotting assays will significantly improve diagnosis of patients with RBDs. In addition, new therapeutic modalities, both recombinant and plasma derived, are emerging, at least in developed countries. Registries and clinical trials have demonstrated decreased bleeding and improved outcomes when patients are appropriately diagnosed and properly treated. Expansion and harmonization of international registries has been initiated to correlate genotype, laboratory, and clinical phenotypes including bleeding severity to improve the diagnosis and therapeutic approach. This review focuses on the latest advances in our understanding, diagnosis, and treatment of RBDs.

Influence of washing conditions on effective components of prothrombin complex concentrates

In order to increase the yield of prothrombin complex concentrates (PCCs) and to reduce their associated thrombotic risks, the influence of washing conditions on the yield, purity, and balance of coagulation factors (FII, FVII, FIX, and FX), and inhibitor proteins (PC, PS, PZ, and AT [antithrombin]) in PCCs was investigated by orthogonal testing, in which three variables (sodium citrate, NaCl, and pH) and their three levels were selected. It was found that AT yield and purity were extraordinarily low, and at lower NaCl content, the general yield, purity, and balance were higher, lower, and better, respectively; however, the results became contrary at higher NaCl. Moreover, within the investigated levels, NaCl was the first determinant for the yield except AT and the purity except FVII, PC, PS, and AT. Sodium citrate was the first determinant for AT yield and FVII, PS, and AT purity. The yield except FII, PS, and AT decreased and the purity except PC increased with increase of sodium citrate content. Just for PC purity, pH was the first determinant. The effect with pH fluctuation on the yield and purity was characteristically unobvious. The outcome undoubtedly supplies the guidance to further improve PCCs.

Use of pharmacokinetic modelling to individualize FFP dosing in factor V deficiency

Therapy with fresh frozen plasma (FFP) confers serious risks, such as contraction of blood-borne viruses, allergic reaction, volume overload and development of alloantibodies. The aim of this study was to apply principles of pharmacokinetic (PK) modelling to individual factor content of FFP to optimize individualized dosing, while minimizing potential risks of therapy. We used PK modelling to successfully target individual factor replacement in an 8-month-old patient receiving FFP for treatment of a severe congenital factor V (FV) deficiency. The model fit for the FV activity vs. time data was excellent (r = 0.98) and the model accurately predicted FV activity during the intraoperative and postoperative period. Accurate PK modelling of individual factor activity in FFP has the potential to provide better targeted therapy, enabling clinicians to more precisely dose patients requiring coagulation products, while avoiding wasteful and expensive product overtreatment, minimizing potentially life-threatening complications due to undertreatment and limiting harmful product-associated risks.

Factor VII deficiency: a single-center experience

Congenital factor VII deficiency is the most common form of rare coagulation factor deficiencies. This article presents a retrospective evaluation of 73 factor VII deficiency cases that had been followed at our center. The study consisted of 48 males and 25 females (2 months-19 years). Thirty-one (42.5%) of them were asymptomatic. Out of symptomatic patients, 17 had severe clinical symptoms, whereas 8 presented with moderate and 17 with mild symptoms. The symptoms listed in order of frequency were as follows: epistaxis, petechia or ecchymose, easy bruising, and oral cavity bleeding. The genotype was determined in 8 patients. Recombinant activated factor VII (rFVIIa) was used to treat 49 bleeding episodes in 8 patients after 2002. In 2 patients with repeated central nervous system bleeding prophylaxis with rFVIIa was administered. No allergic and thrombotic events were observed during both treatment and prophylaxis courses. Antibody occurrence was not detected in the patients during treatment.

Management of children with inherited mild bleeding disorders undergoing adenotonsillar procedures

OBJECTIVE

To evaluate the incidence of perioperative bleeding among children with mild bleeding disorders who underwent adenotonsillar surgery in our hospital and were treated with our perioperative bleeding prophylaxis protocol.

METHODS

Retrospective chart review was aimed at determining the perioperative bleeding rate in children with mild bleeding disorders subjected to our prophylactic protocol while undergoing adenotonsillar procedures. Low von Willebrand factor (LVWF), unspecific platelet function disorders (UPFD) and mild factor VII deficiency were considered as mild bleeding disorders. The protocol utilizes intravenous desmopressin, tranexamic acid, NSAID avoidance, and overnight observation.

RESULTS

Between 2004 and 2009, 44 children with mild bleeding disorders underwent adenotonsillar procedures in our hospital and were treated with the protocol. One patient (LVWF+UPFD) developed perioperative bleeding (2.3%).

CONCLUSIONS

It is possible to obtain low rates of perioperative bleeding in children with mild bleeding disorders undergoing adenotonsillar procedures, provided there is a well-timed diagnosis and an adequate prophylaxis protocol. We believe that further efforts must be directed at preoperative diagnosis of mild bleeding disorders to ensure safer surgeries.

Prothrombin Complex Concentrate Such as Therapy and Prophylaxis in Factor X-Deficient Patient (Friuli Variant)

Background: Factor X (FX) deficiency is a serious, rare bleeding disorder, with 1 in 500 000 affected people. Hemorrhages, hematuria, epistaxis, and other bleeding complications are frequent. Case Report: Now, we report a case of a well-known 77-year-old FX-deficient patient (Friuli variant, level <1%, mutation Pro343→Ser, exon VIII) with hypertension, chronic obstructive pulmonary disease (COPD), and chronic gastritis, admitted many times to hospital due to surgical complications after aortic abdominal aneurysm (AAA) repair. Use of prothrombin complex concentrate (PCC) such as hemostatic therapy during surgeries and prophylaxis after discharge is shown in this article. Three consecutive surgeries were considered. First, endoleak postendoprosthesis; second, AAA breakage; and third, planned surgery, a new endovascular prosthesis positioning and femur-femoral bypass. No adverse events due to PCC were found by local physicians. Discussion: We discuss the methods commonly used in the treatment and prophylaxis of patients with FX deficiency to reduce hemorrhagic risk and to improve their quality of life. Conclusion: Waiting for specific therapeutic options for FX deficiency, currently, the best treatment is represented by PCC. Its correct use permits an improvement in life quality and a reduction in bleeding frequency in FX-deficient patients.

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.

Knowledge, attitudes, and behaviors of youths in the US hemophilia population: results of a national survey

OBJECTIVES

The National Hemophilia Foundation and the Centers for Disease Control and Prevention conducted a national survey focusing on knowledge about, attitudes toward, and behaviors associated with key prevention activities among youths with hemophilia and used the data gathered to design a health promotion campaign.

METHODS

A national, random sample of 459 patients was drawn from 20 hemophilia treatment centers and 8 hemophilia associations; 110 (24%) of the respondents were young people. A telephone questionnaire was used to measure knowledge, behaviors, and barriers to prevention.

RESULTS

Thirty-six percent of the youth respondents believed that joint disease cannot be prevented; 60% managed hemophilia by avoiding physical activity. Only 31% of the respondents treated bleeding episodes within 1 hour. Although hepatitis was a clear threat to this hemophilic cohort, 78% did now know transmission routes for hepatitis C, and 67% did not know transmission routes for hepatitis B.

CONCLUSIONS

Young people with chronic disorders need help understanding that they can prevent complications. We identified key messages for a hemophilia prevention campaign, including exercising to ensure healthy joints and treating bleeding episodes early and adequately.

Management of bleeding emergencies: when to use recombinant activated Factor VII

Recombinant activated Factor VII (rVIIa) was originally released as a clotting factor, with use limited to a select group of patients who had few other treatment options. Due to the apparent ability of rVIIa to stop bleeding, no matter what the underlying cause, there is great interest in use of rVIIa in a wide range of bleeding patients. This article discusses rVIIa and its uses in a variety of patients, especially liver disease and trauma patients, and makes suggestions for appropriate use. Although most of the reports on rVIIa are anecdotes and case series, there is increasing data for clinical trials to help guide usage.

Recessively inherited coagulation disorders

Deficiencies of coagulation factors other than factor VIII and factor IX that cause bleeding disorders are inherited as autosomal recessive traits and are rare, with prevalences in the general population varying between 1 in 500 000 and 1 in 2 million for the homozygous forms. As a consequence of the rarity of these deficiencies, the type and severity of bleeding symptoms, the underlying molecular defects, and the actual management of bleeding episodes are not as well established as for hemophilia A and B. We investigated more than 1000 patients with recessively inherited coagulation disorders from Italy and Iran, a country with a high rate of recessive diseases due to the custom of consanguineous marriages. Based upon this experience, this article reviews the genetic basis, prevalent clinical manifestations, and management of these disorders. The steps and actions necessary to improve the condition of these often neglected patients are outlined.

The rare coagulation disorders - review with guidelines for management from the United Kingdom Haemophilia Centre Doctors' Organisation

The rare coagulation disorders are heritable abnormalities of haemostasis that may present significant difficulties in diagnosis and management. This review summarizes the current literature for disorders of fibrinogen, and deficiencies of prothrombin, factor V, FV + VIII, FVII, FX, the combined vitamin K-dependent factors, FXI and FXIII. Based on both collective clinical experience and the literature, guidelines for management of bleeding complications are suggested with specific advice for surgery, spontaneous bleeding, management of pregnancy and the neonate. We have chosen to include a section on Ehlers-Danlos Syndrome because haematologists may be consulted about bleeding manifestations in such patients.

Successful prophylactic treatment for bleeding in a girl with severe hereditary prothrombin deficiency using a prothrombin complex concentrate (Bebulin VH)

The authors describe the evaluation and course of severe hereditary prothrombin deficiency in a 14-year-old girl first diagnosed at age 4 years. Detailed is the evolution of her treatment from episodic fresh-frozen plasma after bleeding events to prophylactic home infusions with the prothrombin complex concentrate Bebulin VH. Pharmacokinetic data on factor II recovery and half-life are presented. The patient has been essentially free of abnormal bleeding while on this prophylactic regimen for 17 months, with no toxicities and with a much improved quality of life.

Management of the patient with coagulation disorders

Understanding normal haemostasis and the pathophysiology of its disorders is essential for providing optimal care and ensuring judicious usage of blood products, as is keeping abreast of novel therapeutic modalities in a rapidly evolving field. The growing availability of synthetic coagulation factors has (at least in the western hemisphere) helped to reduce morbidity and therapeutic complications, while expanding the indications and usage of these agents. Promising advances in gene therapy may indeed introduce a sea change in the next decade or two.