Systemic bevacizumab for high-output cardiac failure in hereditary hemorrhagic telangiectasia: an international survey of HHT centers

Glycogen storage disease type V: delayed diagnosis of a cause of exercise intolerance in a patient with hereditary haemorrhagic telangiectasia

Hereditary haemorrhagic telangiectasia (HHT) is a genetic disorder characterised by epistaxis, mucocutaneous telangiectasias and arteriovenous malformations. Iron deficiency due to chronic bleeding events is a common manifestation that produces a range of nonspecific symptoms. We report on a patient with HHT with longstanding fatigue and exercise intolerance, which was persistently attributed to iron deficiency, who was revealed to have glycogen storage disease type V, an autosomal recessive metabolic myopathy caused by deficiency of myophosphorylase due to PYGM variants. Genetic testing revealed a pathogenic common exon mutation of one allele and a pathogenic intronic mutation of the other, possibly suggestive of a milder phenotype. We not only detail the first case of concurrent HHT and glycogen storage disease in the literature but more importantly emphasise the need for clinician awareness of the disorders to avoid perpetuating a biased clinical impression and delay in diagnosis as well as prevent potentially harmful interventions.

Efficacy of bevacizumab in hereditary hemorrhagic telangiectasia: a systematic review and network meta-analysis

BACKGROUND

Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal multi-systemic vascular dysplasia caused by gene mutations that lead to recurrent epistaxis and other serious complications including mucocutaneous telangiectasias, gastrointestinal bleeding, and arteriovenous malformations. Treatment is limited to symptomatic relief with no approved standard therapy. Bevacizumab is a monoclonal antibody used primarily in treating metastatic malignancies and ophthalmology. Several studies have shown that bevacizumab is effective in the treatment of HHT-related epistaxis with a high safety profile.

PURPOSE

This systematic review and network meta-analysis aims to explore the efficacy and safety of bevacizumab in the treatment of HHT epistaxis.

METHODS

A comprehensive literature search was done in many databases, including PubMed, Web of Science, Scopus, and the Cochrane Library. We conducted our network meta-analysis using R version 4.2.2 and R Studio version 2022.07.2. Dichotomous data was analyzed as risk ratio and 95% confidence interval and continuous data as mean difference and 95% confidence interval.

RESULTS

We included four randomized clinical trials in our network meta-analysis. Different doses of bevacizumab failed to yield any statistically significant difference in reducing the epistaxis severity score, the number of epistaxis episodes, the duration of epistaxis, or improving hemoglobin levels compared to placebo or other comparators. The pooled effect sizes for all outcomes were homogenous.

CONCLUSION

Bevacizumab failed to show any significant difference compared to tranexamic acid, estriol, or placebo. These findings underscore the challenges in addressing HHT-related symptoms and highlight the ongoing need for innovative and more effective interventions.

Pulmonary vascular manifestations of hereditary haemorrhagic telangiectasia

Hereditary haemorrhagic telangiectasia (HHT) is an autosomal dominant, multisystem disorder that manifests with a spectrum of disease including cardiopulmonary complications. HHT is characterised by aberrant signalling via the transforming growth factor β (TGFβ) pathway, with loss of vascular integrity, angiogenesis and vascular dysplasia. The disease has an estimated prevalence of 1 in 5000 persons and the penetrance increases with increasing age. HHT commonly presents with epistaxis and telangiectasia, while visceral arteriovenous malformations are not uncommon. Mutations in the ENG, ACVRL1 and MADH4 genes account for 97% of all HHT cases, and it is recommended that genetic tests are used in combination with the clinical Curaçao criteria to confirm the diagnosis. HHT can be complicated by significant pulmonary vascular disease including pulmonary arteriovenous malformations, pulmonary arterial hypertension and high output cardiac failure. These are associated with substantial morbidity and mortality and therefore timely diagnosis is important to mitigate complications and optimise preventative strategies. This article outlines important advances in our understanding of the pathobiology of HHT and current recommendations regarding the diagnosis and screening of HHT with a specific focus on adult patients with pulmonary vascular disease. Important therapeutic advances, novel therapies on the horizon and unmet needs are also explored.

How I treat bleeding in hereditary hemorrhagic telangiectasia

ABSTRACT

Hereditary hemorrhagic telangiectasia (HHT; Osler-Weber-Rendu disease) affects 1 in 5000 persons, making it the second most common inherited bleeding disorder worldwide. Telangiectatic bleeding, primarily causing recurrent epistaxis and chronic gastrointestinal bleeding, is the most common and most important manifestation of this multisystem vascular disorder. HHT-associated bleeding results in substantial psychosocial morbidity and iron deficiency anemia that may be severe. Although there remain no regulatory agency-approved therapies for HHT, multiple large studies, including randomized controlled trials, have demonstrated the safety and efficacy of antifibrinolytics for mild-to-moderate bleeding manifestations and systemic antiangiogenic drugs including pomalidomide and bevacizumab for moderate-to-severe bleeding. This has led to a recent paradigm shift away from repetitive temporizing procedural management toward effective systemic medical therapeutics to treat bleeding in HHT. In this article, 4 patient cases are used to illustrate the most common and most challenging presentations of HHT-associated bleeding that hematologists are likely to encounter in daily practice. Built on a framework of published data and supported by extensive clinical experience, guidance is given for modern evidence-based approaches to antifibrinolytic therapy, antiangiogenic therapy, and iron deficiency anemia management across the HHT disease severity spectrum.

Hereditary hemorrhagic telangiectasia may be the most morbid inherited bleeding disorder in women

ABSTRACT

Hereditary hemorrhagic telangiectasia (HHT) is the second-most common inherited bleeding disorder (BD) worldwide and remains without approved therapies. HHT causes serious mucosal bleeding resulting in severe iron-deficiency anemia, major psychosocial complications, and visceral arteriovenous malformations in the brain, lung, and liver, which can cause life-threatening hemorrhagic complications. No study has examined the relative morbidity of HHT and von Willebrand disease (VWD), which is the most common inherited BD in women. We performed an observational cohort study of women with HHT or VWD, comparing a representative sample of 100 randomly selected women with HHT to 100 randomly selected age-matched women with VWD. In HHT vs VWD, recurrent epistaxis and gastrointestinal bleeding were more likely (odds ratio [OR], 32.73 [95% confidence interval, 13.81-71.80]; P < .0001 and 5.69 [2.59-12.89]; P < .0001) and heavy menstrual bleeding was less likely (OR, 0.32 [0.18-0.57]; P < .0001). Iron-deficiency anemia was significantly more likely, and the lowest hemoglobin was significantly lower in HHT than in VWD. The odds of iron infusion dependence, requirement for red cell transfusion, and hemostatic surgical procedures were significantly higher-17-fold, threefold, and eightfold higher, respectively-and hospital admissions to manage disease complications were both ∼14 times more frequent in women with HHT vs those with VWD. In conclusion, much higher disease-related morbidity, mortality, and health care use were observed in women with HHT vs VWD, providing evidence that HHT may be the most clinically significant inherited BD in women. Given the vast gap in research funding for HHT compared with both hemophilia (a disease primarily of men) and VWD, these findings have significant implications for gender equity in hematology.

Defining the Role of Oral Pathway Inhibitors as Targeted Therapeutics in Arteriovenous Malformation Care

Arteriovenous malformations (AVMs) are vascular malformations that are prone to rupturing and can cause significant morbidity and mortality in relatively young patients. Conventional treatment options such as surgery and endovascular therapy often are insufficient for cure. There is a growing body of knowledge on the genetic and molecular underpinnings of AVM development and maintenance, making the future of precision medicine a real possibility for AVM management. Here, we review the pathophysiology of AVM development across various cell types, with a focus on current and potential druggable targets and their therapeutic potentials in both sporadic and familial AVM populations.

Rare bleeding disorders: Advances in management

Inherited factor coagulation deficiencies and vascular bleeding disorders, associated with bleeding of various severity, are often classified as rare bleeding disorders (RBDs). These include inherited fibrinogen disorders, inherited platelet function disorders (IPFD) and hereditary haemorrhagic telangiectasia (HHT). In the last decades, there have been large increases in knowledge on the epidemiology, genetics, physiopathology, clinical features, and diagnosis of RBDs, but improvements in management have been more limited and remain challenging. The treatment mainstay of RBDs is based only on replacement of a few available coagulation factor concentrates or cryoprecipitates. There is growing interest in therapeutic agents that enhance coagulation or inhibiting anticoagulant pathways in RBDs. In severe IPFD, the optimal platelet transfusion strategy is not yet established. Moreover, data is scarce on the effectiveness and safety of desmopressin and/or antifibrinolytic drugs often used for milder IPFD treatment. The best fibrinogen replacement strategy (prophylaxis vs. on demand) in afibrinogenemia is still debated. Similarly, the optimal trough fibrinogen target level for treatment of acute bleeding, and the role of fibrinogen replacement during pregnancy in mild hypofibrinogenemia and dysfibrinogenemia, have not been properly evaluated. The therapeutic arsenal in HHT includes antifibrinolytics and a series of antiangiogenic agents whose potential efficacy has been tested in small studies or are under investigation for treatment of bleeding. However, there is need to address several issues, including the optimal dosing strategies, the potential emergent toxicity of longer-term use, and the impact of systemic antiangiogenic treatment on visceral arteriovenous malformations.

Surgery or No Surgery? Exploring the Dilemma of Epistaxis Management in Patients with HHT

Background: Epistaxis, particularly in Hereditary Hemorrhagic Telangiectasia (HHT) patients, is a common otolaryngological emergency, often requiring complex management. A hierarchy of increasingly invasive interventions, from external compression of the nasal pyramid to nostril closure, is typically proposed and applied. Methods: We conducted a retrospective study on HHT patients to assess the effectiveness and longevity of invasive procedures postoperatively. Data were collected using the Epistaxis Severity Score (ESS) questionnaire. The primary focus was on changes in the frequency and intensity of epistaxis, while the secondary focus was on the overall quality of life. Results: This study found that invasive procedures initially improved the frequency and intensity of epistaxis in HHT patients. However, within 1 to 9 months postoperatively, these benefits often diminished, with hemorrhagic symptoms recurring at similar or worsened levels. Conclusions: The findings suggest a need for a cautious and restrained approach to using invasive treatments in managing epistaxis in HHT patients. Highly invasive procedures should be reserved for cases where less invasive methods fail, due to their temporary effectiveness and the risk of causing anatomical-functional changes in the rhino-sinus area, complicating future management of severe epistaxis.

Meta-analysis of efficacy and safety of bevacizumab in the treatment of hereditary hemorrhagic telangiectasia epistaxis

Objective: A meta-analysis is conducted to evaluate the effectiveness and safety of bevacizumab in hereditary hemorrhagic telangiectasia (HHT) epistaxis. Method: Two researchers search PubMed, EMBASE and Web of Science databases from their inception until September 3th, 2023. The literature is read and screened, and valid data extracted, collated and analyzed. Its quality is then assessed using the Cochrane risk assessment scale. This study uses Endnote 9.3 software for literature management and RevMan 5.3.1 software for evaluation. Results: A total of 7 documents met the requirements, including a total of 359 patients, and the literature quality evaluation was grade B. The Meta-analysis results showed that:Bevacizumab reduces the Epistaxis Severity Score (ESS) in patients with HHT epistaxis compared with the control [WMD = -0.22,95%CI (-0.38, -0.05), p = 0.01]. However, there is no significant effect on duration of epistaxis [WMD = -15.59, 95%CI (-70.41,39.23), p = 0.58] and number of epistaxes [WMD = -1.27,95%CI (-10.23,7.70), p = 0.78] in patients with HHT epistaxis. In terms of adverse effects, there is no significant difference between the bevacizumab group and control group [OR = 1.36, 95% CI (0.54, 3.44), p = 0.52]. Conclusion: Bevacizumab is superior to the control group in the treatment of HHT epistaxis, and adverse reactions are not further increased in the bevacizumab group than in the control group, suggesting that bevacizumab has clinical value in the treatment of HHT epistaxis.

Efficacy and safety of intravenous bevacizumab on severe bleeding associated with hemorrhagic hereditary telangiectasia: A national, randomized multicenter trial

BACKGROUND

Bevacizumab-a humanized monoclonal antibody-has been widely used to treat patients with hereditary hemorrhagic telangiectasia (HHT), but no randomized trial has yet been conducted.

METHODS

This study is a double-blind multicenter randomized phase 2 trial with a 1:1 active-treatment-to-placebo ratio. We included patients over the age of 18 with a confirmed diagnosis and the need for at least four red blood cell (RBC) units transfused in the 3 months before study enrollment. Bevacizumab was administered at a dose of 5 mg/kg every 14 days with a total of six injections. The primary efficacy criterion was a decrease of at least 50% in the cumulative number of RBC units transfused in a 3-month period before and after treatment.

RESULTS

A total of 24 patients (12 in each group) were included and randomized at 4 different centers. In intention-to-treat analysis, 63.6% of patients (7/11) in the bevacizumab group versus 33.3% of patients (4/12) in the placebo group decreased the number of blood transfusions by at least 50% (p = 0.22). Hemoglobin levels significantly improved at 6 months in the bevacizumab versus placebo group (p = 0.02). The pharmacokinetics study revealed that patients with high exposure to bevacizumab had a significant decrease in RBC transfusions (p = 0.03). Fifty-nine adverse events were observed, 34 in the placebo arm versus 25 in the bevacizumab arm.

CONCLUSION

Though the present trial was underpowered, patients with HHT receiving bevacizumab required numerically fewer red blood cell transfusions than those receiving placebo, particularly those with high exposure.

Pulmonary hypertension in hereditary hemorrhagic telangiectasia: A clinical review

Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant hereditary disorder characterized by recurrent spontaneous epistaxis, mucocutaneous telangiectasias, and solid organ arteriovenous malformations (AVMs). Pulmonary hypertension (PH) is an increasingly recognized complication in patients with HHT, most often precipitated by high-output heart failure in the presence of hepatic AVMs as well as pulmonary arterial hypertension in the form of a proliferative vasculopathy. The presence of PH in patients with HHT is associated with significant elevations in rates of morbidity and mortality. Additionally, there is growing recognition of a thromboembolic propensity in this population that increases the risk of chronic thromboembolic PH, posing unique clinical considerations regarding the use of anticoagulation. Patients with HHT are also at risk of PH due to disorders commonly seen in the general population, including left-sided heart and lung disease. The etiology of PH in HHT is multifaceted and complex; the diagnostic approach and treatment strategies must consider the underlying pathophysiology of HHT. This comprehensive review summarizes current knowledge of PH in HHT, detailing the pathogenesis of known etiologies, diagnostic evaluation, and suggested treatment modalities as well as emerging therapies that may be of future interest.

Hereditary Hemorrhagic Telangiectasia-A Case Series Experience from a Liver Transplant Center in Romania

Hereditary hemorrhagic telangiectasia (HHT) has significant morbidity due to multiorgan involvement and an unpredictable disease course. We analyzed the data of 14 patients diagnosed with HHT. The case series comprised 14 patients with a median age at presentation of 48 years old (41-74 years). In twelve patients (85.7%), the diagnosis was confirmed by using the Curacao Criteria. The most common reason for admission was epistaxis, with 9 patients (57%) presenting with nosebleed refractory to prolonged self-tamponade. The biochemical abnormalities identified were elevations in AP and gamma-GT; liver synthetic function was generally normal, even though 21% of patients had clinical or imaging findings for cirrhosis. Nosebleeds were the main reason for admission and significantly impacted quality of life through anemia and frequent hospital admissions. However, the visceral manifestations seemed to be more serious. The hepatic arteriovenous malformations (AVMs) appeared to remain asymptomatic or led to minimal changes for the majority of patients; some cases were associated with liver and biliary tract ischemia, necrosis leading to acute liver failure and even death. Hepatic AVMs can also lead to high-output heart failure due to arterio-venous shunting. The most frequent AVM was hepatic artery to hepatic vein, with secondary hepatic vein dilation and hemodynamic consequences.

An update on preclinical models of hereditary haemorrhagic telangiectasia: Insights into disease mechanisms

Endoglin (ENG) is expressed on the surface of endothelial cells (ECs) where it efficiently binds circulating BMP9 and BMP10 ligands to initiate activin A receptor like type 1 (ALK1) protein signalling to protect the vascular architecture. Patients heterozygous for ENG or ALK1 mutations develop the vascular disorder known as hereditary haemorrhagic telangiectasia (HHT). Many patients with this disorder suffer from anaemia, and are also at increased risk of stroke and high output heart failure. Recent work using animal models of HHT has revealed new insights into cellular and molecular mechanisms causing this disease. Loss of the ENG (HHT1) or ALK1 (HHT2) gene in ECs leads to aberrant arteriovenous connections or malformations (AVMs) in developing blood vessels. Similar phenotypes develop following combined EC specific loss of SMAD1 and 5, or EC loss of SMAD4. Taken together these data point to the essential role of the BMP9/10-ENG-ALK1-SMAD1/5-SMAD4 pathway in protecting the vasculature from AVMs. Altered directional migration of ECs in response to shear stress and increased EC proliferation are now recognised as critical factors driving AVM formation. Disruption of the ENG/ALK1 signalling pathway also affects EC responses to vascular endothelial growth factor (VEGF) and crosstalk between ECs and vascular smooth muscle cells. It is striking that the vascular lesions in HHT are both localised and tissue specific. Increasing evidence points to the importance of a second genetic hit to generate biallelic mutations, and the sporadic nature of such somatic mutations would explain the localised formation of vascular lesions. In addition, different pro-angiogenic drivers of AVM formation are likely to be at play during the patient’s life course. For example, inflammation is a key driver of vessel remodelling in postnatal life, and may turn out to be an important driver of HHT disease. The current wealth of preclinical models of HHT has led to increased understanding of AVM development and revealed new therapeutic approaches to treat AVMs, and form the topic of this review.

Systemic bevacizumab as salvage therapy for persistent severe bleeding and anemia in heyde syndrome following aortic valve replacement

Heyde syndrome is characterized by the co-occurrence of aortic stenosis and bleeding gastrointestinal angiodysplasias, often with acquired von Willebrand syndrome. Current management for bleeding includes hematologic support with red cell transfusion and intravenous iron and correction of aortic stenosis with valve replacement. However, persistent Heyde syndrome after valve replacement occurs in a significant minority of cases, and there is no accepted therapy for these patients. Given that the pathophysiology of angiodysplasia formation in Heyde syndrome involves dysregulated angiogenesis, targeting angiogenesis may be an effective therapeutic option. We describe two cases of persistent Heyde syndrome with severe bleeding and anemia in patients following aortic valve replacement who were treated with systemic bevacizumab, a monoclonal antibody directed against vascular endothelial growth factor. In both cases, treatment was successful, with resolution of bleeding, liberation from hematologic support, and normalization of hemoglobin. In addition to responding to therapy, neither patient had treatment-related adverse events (and both had recurrent anemia upon treatment discontinuation, further evidence of the therapeutic impact of bevacizumab). Additional investigation into the use of systemic antiangiogenic therapy for treatment of Heyde syndrome is warranted.

Cardiac and Hemodynamic Manifestations of Hereditary Hemorrhagic Telangiectasia

The autosomal dominant trait hereditary hemorrhagic telangiectasia (HHT) causes multiorgan dysplastic lesions of the vasculature that can activate multiple physiological cascades leading to a broad array of cardiovascular diseases. Up to 78% of patients with HHT develop hepatic arteriovenous malformations (AVMs), which cause a hyperdynamic circulatory state secondary to hepatic/portal shunting. This condition can eventually progress to high-output cardiac failure (HOCF) with continued peripheral tissue hypoxemia. Treatment for HOCF is often limited to supportive measures (diuretics and treatment of anemia); however, recent studies using systemic bevacizumab have shown promise by substantially reducing the cardiac index. In the context of liver AVMs and high cardiac output, the pulmonary vasculature can also experience high flow. Without adequate dilation of pulmonary vessels, post-capillary pulmonary hypertension can develop. Another form of pulmonary hypertension observed in HHT, pulmonary arterial hypertension, is caused by HHT-related mutations in ENG and ACVRL1 causing congestive arteriopathy. Post-capillary pathogenesis is addressed by reducing the high-output state, whereas the pre-capillary state is treated with supportive mechanisms (diuretics, oxygen) and agents targeting pulmonary vasoreactivity: endothelin-1 receptor antagonists and phosphodiesterase-5 inhibitors. If either form of pulmonary hypertension is left untreated or proves refractory and progresses, the common hemodynamic complication is right heart failure. Targeted right heart therapies involve similar strategies to those of pulmonary arterial hypertension, with several experimental approaches under study. In this review, we describe in detail the mechanisms of pathogenesis, diagnosis, and treatment of the hemodynamic complications and associated cardiovascular diseases that may arise in patients with HHT.

Systemic Antiangiogenic Therapies for Bleeding in Hereditary Hemorrhagic Telangiectasia: A Practical, Evidence-Based Guide for Clinicians

Management of bleeding in hereditary hemorrhagic telangiectasia (HHT), the second most common hereditary bleeding disorder in the world, is currently undergoing a paradigm shift. Disease-modifying antiangiogenic therapies capable of achieving durable hemostasis via inducing telangiectasia regression have emerged as a highly effective and safe modality to treat epistaxis and gastrointestinal bleeding in HHT. While evidence to date is incomplete and additional studies are ongoing, patients presently in need are being treated with antiangiogenic agents off-label. Intravenous bevacizumab, oral pazopanib, and oral thalidomide are the three targeted primary angiogenesis inhibitors, with multiple studies describing both reassuring safety and impressive effectiveness in the treatment of moderate-to-severe HHT-associated bleeding. However, at present there is a paucity of guidance in the literature, including the published HHT guidelines, addressing the practical aspects of antiangiogenic therapy for HHT in clinical practice. This review article and practical evidence-based guide aims to fill this unaddressed need, synthesizing published data on the use of antiangiogenic agents in HHT, relevant data for their use outside of HHT, and expert guidance where evidence is lacking. After a brief review of principles of bleeding therapy in HHT, guidance on hematologic support with iron and blood products, and alternatives to antiangiogenic therapy, this article examines each of the aforementioned antiangiogenic agents in detail, including patient selection, initiation, monitoring, toxicity management, and discontinuation. With proper, educated use of antiangiogenic therapies in HHT, patients with even the most severe bleeding manifestations can achieve durable hemostasis with minimal side-effects, dramatically improving health-related quality of life and potentially altering the disease course.

A retrospective cohort study on European Reference Network for Rare Vascular Diseases 5 outcome measures for Hereditary Haemorrhagic Telangiectasia in Denmark

Background

Hereditary Haemorrhagic Telangiectasia (HHT) is an autosomal dominant disorder characterized by several clinical symptoms including epistaxis, arteriovenous malformations (AVM), and telangiectasia. In 2018, European Reference Network for Rare Vascular Diseases (VASCERN) recommended five outcome measures for HHT-patients to guide health care providers, some with limited experience in treating HHT, and thereby maximizing the number of HHT-patients receiving good care. The outcome measures cover the following aspects: (1) 90% of the patients should receive a pulmonary AVM (PAVM) screening; (2) 90% of the patients should receive written advice on nosebleed; (3) 70% should be assessed for iron deficiency; (4) 100% of the patients should receive written advice on antibiotic (AB) prophylaxis prior to dental and surgical procedures, and (5) 100% of relevant patients should receive written advice on pregnancy. We have introduced the outcome measures as Benchmarks in our HHT-centre and wanted to evaluate the extend of implementation we have achieved. We constantly struggle to secure the best possible treatment of our HHT-patients.

Methods

The study was a non-interventional retrospective study. Data was collected manually from patient records and from the Danish HHT-database.

Results

A total of 180 HHT-patients were included, all diagnosed in the period from January 1st, 2016, to December 31st, 2020. All patients were screened for PAVM. We could confirm that 66% of patients who had epistaxis received thoroughly advice. Assessment for iron deficiency was performed in 80% of the adult patients. Thoroughly advice on AB prophylaxis was documented in 75%. Thoroughly advice on pregnancy was documented in 80% of female patients 15–45 years of age. There were no significant differences over time for any of the outcome measures.

Conclusions

The Danish HHT-centre reached the target threshold for outcome measures 1 and 3. It could not be documented that the target thresholds for outcome measures 2, 4, and 5 were achieved. As information and education are a very important part of HHT care, focus on and documentation that all patients receive the relevant advice must be a priority in order to ensure best care.

Review of treatment and therapeutic targets in brain arteriovenous malformation

Brain arteriovenous malformations (bAVM) are an important cause of intracranial hemorrhage (ICH), especially in younger patients. The pathogenesis of bAVM are largely unknown. Current understanding of bAVM etiology is based on studying genetic syndromes, animal models, and surgically resected specimens from patients. The identification of activating somatic mutations in the Kirsten rat sarcoma viral oncogene homologue (KRAS) gene and other mitogen-activated protein kinase (MAPK) pathway genes has opened up new avenues for bAVM study, leading to a paradigm shift to search for somatic, de novo mutations in sporadic bAVMs instead of focusing on inherited genetic mutations. Through the development of new models and understanding of pathways involved in maintaining normal vascular structure and functions, promising therapeutic targets have been identified and safety and efficacy studies are underway in animal models and in patients. The goal of this paper is to provide a thorough review or current diagnostic and treatment tools, known genes and key pathways involved in bAVM pathogenesis to summarize current treatment options and potential therapeutic targets uncovered by recent discoveries.

Systemic bevacizumab to facilitate anticoagulation in antiphospholipid syndrome and bleeding gastrointestinal angiodysplasia

Bleeding gastrointestinal angiodysplasia may occur in patients with vasculitis and can be challenging to treat. We describe the novel use of bevacizumab therapy to treat bleeding gastrointestinal angiodysplasia and severe anemia in a patient with eosinophilic granulomatosis with angiitis complicated by antiphospholipid antibody syndrome requiring indefinite warfarin therapy. Studies confirmed multiple bleeding jejunal angiodysplasias unamenable to endoscopic intervention, and the patient required ongoing support with iron infusions and blood transfusions to maintain a minimally acceptable hemoglobin. Given the severe anemia, need for continued, indefinite antiplatelet and anticoagulation therapy, and failure of standard treatment approaches, the patient was initiated on systemic bevacizumab therapy, on the basis of prior documented success of bevacizumab to manage gastrointestinal telangiectasias in patients with hereditary hemorrhagic telangiectasia. Bevacizumab was highly effective, with rapid resolution of bleeding, normalization of hemoglobin, liberation from hematologic support and no adverse events, including no thromboembolic events. Vascular endothelial growth factor (VEGF-A) rose paradoxically after initiation of bevacizumab and normalized after its discontinuation. Given these findings, use of systemic bevacizumab to manage bleeding angiodysplasia in patients with acquired vascular disorders merits further study.

Systemic bevacizumab for refractory bleeding and transfusion-dependent anemia in Heyde syndrome

Heyde syndrome, the co-occurrence of aortic stenosis and bleeding gastrointestinal (GI) angiodysplasia, is managed with aortic valve replacement. However, severe bleeding and anemia can preclude safe use of the antiplatelet or anticoagulant therapy required for this intervention. We present a case of the novel and successful treatment of severe, refractory bleeding and transfusion dependence with antiangiogenic therapy in a patient with Heyde syndrome. After systemic bevacizumab was initiated, the patient achieved durable hemostasis with normalization of hemoglobin and liberation from red cell transfusion and dependence on iron infusion; aspirin therapy was successfully initiated where it had previously failed. This durable hemostasis facilitated her subsequent successful transcatheter aortic valve replacement. Plasma vascular endothelial growth factor levels, which were monitored during therapy, paradoxically rose after bevacizumab was initiated but normalized after it was discontinued. Given the angiogenic dysregulation of Heyde syndrome, systemic bevacizumab may be an effective and safe targeted therapy for managing refractory GI bleeding, which thereby facilitates antiplatelet therapy and aortic valve replacement in these challenging cases. Additional investigation into the therapeutic role of inhibiting angiogenesis as a hemostatic modality in Heyde syndrome is warranted.

Thrombotic and bleeding risk of angiogenesis inhibitors in patients with and without malignancy

Over the past two decades, therapies targeting angiogenesis have developed into a major class of cancer therapeutics. The vascular endothelial growth factor (VEGF) family of signaling proteins, a group of potent angiogenic growth factors, and their receptors represent the main targets of this therapeutic class. To date, 16 antiangiogenic agents have been approved in the United States for the treatment of cancer and several more are in development. An important consideration with antiangiogenic therapy is toxicity, in particular thrombotic and bleeding risks. These complications have emerged as a major clinical concern that may affect the use of these agents in patients both with and without cancer who may already have an elevated risk of thrombosis and bleeding. Although these agents are frequently considered together as a class when contemplating their bleeding and thrombotic risks, in fact the risks for venous thromboembolism, arterial thrombosis, and bleeding vary significantly between different classes of antiangiogenic agents and even among different agents within a class. In this narrative review, we describe the literature investigating the venous and arterial thrombotic and bleeding risks associated with the currently available antiangiogenic drugs. In addition, we discuss these specific complications in the context of both cancer therapy as well as the management of nonmalignant disorders now managed with antiangiogenic agents, including hereditary hemorrhagic telangiectasia and neovascular age-related macular degeneration.

An international, multicenter study of intravenous bevacizumab for bleeding in hereditary hemorrhagic telangiectasia: the InHIBIT-Bleed study

Hereditary hemorrhagic telangiectasia (HHT, Osler-Weber-Rendu disease) is a rare multisystem vascular disorder that causes chronic gastrointestinal bleeding, epistaxis, and severe anemia. Bevacizumab, an anti-vascular endothelial growth factor antibody, may be effective to treat bleeding in HHT. This international, multicenter, retrospective study evaluated the use of systemic bevacizumab to treat HHTassociated bleeding and anemia at 12 HHT treatment centers. Hemoglobin, Epistaxis Severity Score (ESS), red cell units transfused, and intravenous iron infusions before and after treatment were evaluated using paired means testing and mixed-effects linear models. Bevacizumab was given to 238 HHT patients for a median of 12 (range, 1-96) months. Compared with pretreatment, bevacizumab increased mean hemoglobin by 3.2 g/dL (95% confidence interval: 2.9-3.5 g/dL); i.e., from a mean hemoglobin of 8.6 (8.5-8.8) g/dL to 11.8 (11.5-12.1) g/dL; P<0.0001) and decreased the ESS by 3.4 (3.2-3.7) points (mean ESS 6.8 [6.6-7.1] versus 3.4 [3.2-3.7]; P<0.0001) during the first year of treatment. Compared with 6 months before treatment, the number of red blood cell units transfused decreased by 82% (median of 6.0 [interquartile range, 0.0-13.0] units versus 0 [0.0-1.0] units; P<0.0001) and iron infusions decreased by 70% (median of 6.0 [1.0-18.0] infusions versus 1.0 [0.0-4.0] infusions, P<0.0001) during the first 6 months of bevacizumab treatment. Outcomes were similar regardless of the underlying pathogenic mutation. Following initial induction infusions, continuous/scheduled bevacizumab maintenance achieved higher hemoglobin and lower ESS than intermittent/as-needed maintenance but with more drug exposure. Bevacizumab was well tolerated: hypertension, fatigue, and proteinuria were the most common adverse events. Venous thromboembolism occurred in 2% of patients. In conclusion, systemic bevacizumab was safe and effective for managing chronic bleeding and anemia in HHT.

Pazopanib for severe bleeding and transfusion-dependent anemia in hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is a rare angiogenic disorder causing chronic gastrointestinal bleeding, epistaxis, and severe anemia. Pazopanib is an oral multi-kinase angiogenesis inhibitor with promise to treat bleeding in HHT. We analyzed outcomes of HHT patients with the most severe bleeding causing RBC transfusion dependence treated on a predefined institutional pazopanib treatment pathway (with data collected retrospectively). The primary endpoint was achievement of transfusion independence. Secondary endpoints included hemoglobin, epistaxis severity score, RBC transfusion and iron infusion requirements, number of local hemostatic procedures, ferritin and transferrin saturation, compared using paired and repeated measures mean tests. Thirteen transfusion-dependent HHT patients received pazopanib [median (range) dose 150 (25–300) mg daily)] for a median of 22 months. All patients achieved transfusion independence. Compared with pretreatment, pazopanib increased mean hemoglobin by 4.8 (95% CI, 3.6–5.9) g/dL (7.8 vs. 12.7 g/dL, P < 0.0001) and decreased mean epistaxis severity score by 4.77 (3.11–6.44) points (7.20 vs. 2.43 points, P < 0.0001) after 12 months of treatment. Compared with 3 months of pretreatment, RBC transfusions decreased by 93% (median of 16.0 vs. 0.0 units, P < 0.0001) and elemental iron infusion decreased by 92% (median of 4500 vs. 0 mg, P = 0.005) during the first 3 months of treatment; improvements were maintained over time. Pazopanib was well-tolerated: hypertension, lymphocytopenia, and fatigue were the most common TEAEs. In conclusion, pazopanib was safe and effective to manage severe bleeding in HHT, liberating all patients from transfusion dependence and normalizing hematologic parameters at doses lower than used to treat malignancies. These findings require confirmation in a randomized trial.

Hereditary hemorrhagic telangiectasia: systemic therapies, guidelines, and an evolving standard of care

Hereditary hemorrhagic telangiectasia (HHT) management is evolving because of the emergence and development of antiangiogenic therapies to eliminate bleeding telangiectasias and achieve hemostasis. This progress is reflected in recent clinical recommendations published in the Second International Guidelines for the Diagnosis and Treatment of HHT, in which systemic therapies including antiangiogenics and antifibrinolytics are now recommended as standard treatment options for bleeding. This review highlights the new recommendations especially relevant to hematologists in managing bleeding, anticoagulation, and anemia in patients with HHT.

Hereditary Hemorrhagic Telangiectasia in a Sudanese Patient

Background

Hereditary hemorrhagic telangiectasia (HHT) also known as Osler–Weber–Rendu syndrome is a rare autosomal dominant disorder, which results in vascular dysplasia affecting mainly visceral and mucocutaneous organs. Case Presentation. A 65-year-old woman with a 12-year history of recurrent spontaneous epistaxis presented with shortness of breath, easy fatigability, and bilateral lower limb edema. Her family history was significant for definite hereditary hemorrhagic telangiectasia in first-degree relatives. During the previous 15 days, she has experienced three episodes of recurrent nasal bleeding. She has a background of chronic mitral regurgitation. Physical examination revealed telangiectases in her tongue, lower lip, and hand in addition to signs of congestive heart failure. The patient met 3\4 Curacao criteria and had a definite HHT. Her laboratory workup revealed a hemoglobin count of 5.4 g/dl. Echocardiography revealed a left systolic ejection fraction of 51% with left atrial dilatation and severe mitral regurgitation. Chest X-ray showed features of cardiomegaly and pulmonary edema. The abdominal ultrasonography showed enlarged liver size with homogenous texture and congested hepatic veins without features of hepatic AVMs. She was treated with intravenous frusemide, iron supplement, tranexamic acid, blood transfusion, and nasal packing.

Conclusions

HTT usually passes unnoticed in Sudan. The rarity of HHT, difficulties in affording diagnostic imaging studies, and low clinical suspicion among doctors are important contributing factors. Anemia resulting from recurrent epistaxis might have an influential role in precipitating acute heart failure in those with chronic rheumatic valvular disease.

Predictors of mortality in patients with hereditary hemorrhagic telangiectasia

BACKGROUND

Retrospective questionnaire and healthcare administrative data suggest reduced life expectancy in untreated hereditary hemorrhagic telangiectasia (HHT). Prospective data suggests similar mortality, to the general population, in Denmark's centre-treated HHT patients. However, clinical phenotypes vary widely in HHT, likely affecting mortality. We aimed to measure predictors of mortality among centre-treated HHT patients. HHT patients were recruited at 14 HHT centres of the Brain Vascular Malformation Consortium (BVMC) since 2010 and followed annually. Vital status, organ vascular malformations (VMs) and clinical symptoms data were collected at baseline and during follow-up (N = 1286). We tested whether organ VMs, HHT symptoms and HHT genes were associated with increased mortality using Cox regression analysis, adjusting for patient age, sex, and smoking status.

RESULTS

59 deaths occurred over average follow-up time of 3.4 years (max 8.6 years). A history of anemia was associated with increased mortality (HR = 2.93, 95% CI 1.37-6.26, p = 0.006), as were gastro-intestinal (GI) bleeding (HR = 2.63, 95% CI 1.46-4.74, p = 0.001), and symptomatic liver VMs (HR = 2.10, 95% CI 1.15-3.84, p = 0.015). Brain VMs and pulmonary arteriovenous malformations (AVMs) were not associated with mortality (p > 0.05). Patients with SMAD4 mutation had significantly higher mortality (HR = 18.36, 95% CI 5.60-60.20, p < 0.001) compared to patients with ACVRL1 or ENG mutation, but this estimate is imprecise given the rarity of SMAD4 patients (n = 33, 4 deaths).

CONCLUSIONS

Chronic GI bleeding, anemia and symptomatic liver VMs are associated with increased mortality in HHT patients, independent of age, and in keeping with the limited treatment options for these aspects of HHT. Conversely, mortality does not appear to be associated with pulmonary AVMs or brain VMs, for which patients are routinely screened and treated preventatively at HHT Centres. This demonstrates the need for development of new therapies to treat chronic anemia, GI bleeding, and symptomatic liver VMs in order to reduce mortality among HHT patients.

Intravenous Bevacizumab in Hereditary Hemorrhagic Telangiectasia-Related Bleeding and High-Output Cardiac Failure: Significant Inter-Individual Variability in the Need for Maintenance Therapy

OBJECTIVE

To present our center's experience with a maintenance treatment algorithm for intravenous bevacizumab that allows for personalized therapy decisions.

PATIENTS AND METHODS

We reviewed all patients treated with intravenous bevacizumab for hereditary hemorrhagic telangiectasia-related bleeding and/or high-output cardiac failure (HOCF) from January 1, 2013, to July 1, 2019, at the Mayo Clinic, Rochester, Minnesota. Data regarding subsequent bevacizumab dosing were abstracted.

RESULTS

A total of 57 patients (n=40, 70.2% females) were identified with a median age of 65 (55 to 74; range, 37 to 89) years. High-cardiac output state was present in 21 patients (36.8%) and 10 (17.5%) were treated with intravenous bevacizumab primarily for HOCF. The median duration of follow-up after completion of the initial intravenous bevacizumab treatment was 25 (12.3 to 40.8; range, 0.1 to 65.4) months. A total of 20 (35.1%) patients with a median follow-up of 13.5 (range, 0 to 48.4) months required no maintenance dosing throughout the duration of follow-up. Among those who required subsequent maintenance doses, only a small fraction (8 patients; 14.0%) required regular maintenance doses every 4 to 8 weeks during follow-up whereas the majority of patients required intermittent "as-needed" doses at varying intervals.

CONCLUSION

There is significant inter-individual variability in the need for maintenance intravenous bevacizumab when patients are followed using a predefined bevacizumab maintenance dosing treatment algorithm. The use of "as-needed" maintenance bevacizumab appears to be an effective strategy for management of hereditary hemorrhagic telangiectasia-related bleeding and HOCF.

Gender differences in hereditary hemorrhagic telangiectasia severity

Background

Gender differences in organ involvement and clinical severity have been poorly described in hereditary hemorrhagic telangiectasia (HHT). The aim of this study was to describe differences in the severity of HHT manifestations according to gender.

Methods

Severity was measured according to Epistaxis Severity Score (ESS), Simple Clinical Scoring Index for hepatic involvement, a general HHT-score, needing for invasive treatment (pulmonary or brain arteriovenous malformations -AVMs- embolization, liver transplantation or Young’s surgery) or the presence of adverse outcomes (severe anemia, emergency department -ED- or hospital admissions and mortality).

Results

One hundred forty-two (58.7%) women and 100 (41.3%) men were included with a mean age of 48.9 ± 16.6 and 49 ± 16.5 years, respectively. Women presented hepatic manifestations (7.1% vs 0%) and hepatic involvement (59.8% vs 47%), hepatic AVMs (28.2% vs 13%) and bile duct dilatation (4.9% vs 0%) at abdominal CT, and pulmonary AVMs at thoracic CT (35.2% vs 23%) more often than men. The Simple Clinical Scoring Index was higher in women (3.38 ± 1.2 vs 2.03 ± 1.2), and more men were considered at low risk of harboring clinically significant liver disease than women (61% vs 25.3%). These differences were mantained when considering HHT1 and HHT2 patients separetely. Duodenal telangiectasia were more frequent in men than women (21% vs 9.8%). Invasive treatments were more frequently needed in women (28.2% vs 16%) but men needed attention at the ED more often than women (48% vs 28.2%), with no differences in ESS, HHT-score, anemia hospital admissions or mortality.

Conclusions

HHT women showed more severe hepatic involvement than men, also among HHT1 and HHT2 patients. Women had higher prevalence of pulmonary AVMs and needed invasive procedures more frequently, while men needed attention at the ED more often. These data might help physicians to individualize HHT patients follow-up.