Safety of thalidomide and bevacizumab in patients with hereditary hemorrhagic telangiectasia

Potential Second-Hits in Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant genetic disorder that presents with telangiectases in skin and mucosae, and arteriovenous malformations (AVMs) in internal organs such as lungs, liver, and brain. Mutations in ENG (endoglin), ACVRL1 (ALK1), and MADH4 (Smad4) genes account for over 95% of HHT. Localized telangiectases and AVMs are present in different organs, with frequencies which differ among affected individuals. By itself, HHT gene heterozygosity does not account for the focal nature and varying presentation of the vascular lesions leading to the hypothesis of a “second-hit” that triggers the lesions. Accumulating research has identified a variety of triggers that may synergize with HHT gene heterozygosity to generate the vascular lesions. Among the postulated second-hits are: mechanical trauma, light, inflammation, vascular injury, angiogenic stimuli, shear stress, modifier genes, and somatic mutations in the wildtype HHT gene allele. The aim of this review is to summarize these triggers, as well as the functional mechanisms involved.

Endoplasmic Reticulum Associated Protein Degradation (ERAD) in the Pathology of Diseases Related to TGFβ Signaling Pathway: Future Therapeutic Perspectives

The transforming growth factor signaling pathway (TGFβ) controls a wide range of cellular activities in adulthood as well as during embryogenesis including cell growth, differentiation, apoptosis, immunological responses and other cellular functions. Therefore, germline mutations in components of the pathway have given rise to a heterogeneous spectrum of hereditary diseases with variable phenotypes associated with malformations in the cardiovascular, muscular and skeletal systems. Our extensive literature and database searches revealed 47 monogenic diseases associated with germline mutations in 24 out of 41 gene variant encoding for TGFβ components. Most of the TGFβ components are membrane or secretory proteins and they are therefore expected to pass through the endoplasmic reticulum (ER), where fidelity of proteins folding is stringently monitored via the ER quality control machineries. Elucidation of the molecular mechanisms of mutant proteins’ folding and trafficking showed the implication of ER associated protein degradation (ERAD) in the pathogenesis of some of the diseases. For example, hereditary hemorrhagic telangiectasia types 1 and 2 (HHT1 and HHT2) and familial pulmonary arterial hypertension (FPAH) associated with mutations in Endoglin, ALK1 and BMPR2 components of the signaling pathway, respectively, have all exhibited loss of function phenotype as a result of ER retention of some of their disease-causing variants. In some cases, this has led to premature protein degradation through the proteasomal pathway. We anticipate that ERAD will be involved in the mechanisms of other TGFβ signaling components and therefore warrants further research. In this review, we highlight advances in ER quality control mechanisms and their modulation as a potential therapeutic target in general with particular focus on prospect of their implementation in the treatment of monogenic diseases associated with TGFβ components including HHT1, HHT2, and PAH. In particular, we emphasis the need to establish disease mechanisms and to implement such novel approaches in modulating the molecular pathway of mutant TGFβ components in the quest for restoring protein folding and trafficking as a therapeutic approach.

Differential Expression of Circulating Plasma miRNA-370 and miRNA-10a from Patients with Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant, vascular disorder that presents with telangiectases and arteriovenous malformations. HHT is a genetically heterogeneous disorder, involving mutations in endoglin (ENG; HHT1) and activin receptor-like kinase 1 (ACVRL1/ALK1; HHT2) genes that account for over 85% of all HHT patients. The current diagnosis of HHT patients remains at the clinical level, but many suspected patients do not have a clear HHT diagnosis or do not show pathogenic mutations in HHT genes. This situation has prompted the search for biomarkers to help in the early diagnosis of the disease. We have analyzed the plasma levels in HHT patients of selected micro-RNAs (miRNAs), small single-stranded RNAs that regulate gene expression at the transcriptional level by interacting with specific RNA targets. A total of 16 HHT1 and 17 HHT2 plasma samples from clinically confirmed patients and 16 controls were analyzed in this study. Total RNA was purified from plasma, and three selected miRNAs (miRNA-10a, miRNA-214, and miRNA-370), related to the pathobiology of cardiovascular diseases and potentially targeting ENG or ALK1, were measured by quantitative polymerase chain reaction. Compared with controls, levels of miRNA-370, whose putative target is ENG, were significantly downregulated in HHT1, but not in HHT2, whereas the levels of miRNA-10a, whose putative target is ALK1, were significantly upregulated in HHT2, but not in HHT1. In addition, the levels of miRNA-214, potentially targeting ENG and ALK1, did not change in either HHT1 or HHT2 patients versus control samples. While further studies are warranted, these results suggest that dysregulated plasma levels of miRNA-370 or miRNA-10a could help to identify undiagnosed HHT1 or HHT2 patients, respectively.

Review of Pharmacological Strategies with Repurposed Drugs for Hereditary Hemorrhagic Telangiectasia Related Bleeding

The diagnosis of hereditary hemorrhagic telangiectasia (HHT) is based on the Curaçao criteria: epistaxis, telangiectases, arteriovenous malformations in internal organs, and family history. Genetically speaking, more than 90% of HHT patients show mutations in ENG or ACVRL1/ALK1 genes, both belonging to the TGF-β/BMP9 signaling pathway. Despite clear knowledge of the symptoms and genes of the disease, we still lack a definite cure for HHT, having just palliative measures and pharmacological trials. Among the former, two strategies are: intervention at "ground zero" to minimize by iron and blood transfusions in order to counteract anemia. Among the later, along the last 15 years, three different strategies have been tested: (1) To favor coagulation with antifibrinolytic agents (tranexamic acid); (2) to increase transcription of ENG and ALK1 with specific estrogen-receptor modulators (bazedoxifene or raloxifene), antioxidants (N-acetylcysteine, resveratrol), or immunosuppressants (tacrolimus); and (3) to impair the abnormal angiogenic process with antibodies (bevacizumab) or blocking drugs like etamsylate, and propranolol. This manuscript reviews the main strategies and sums up the clinical trials developed with drugs alleviating HHT.

An international survey to evaluate systemic bevacizumab for chronic bleeding in hereditary haemorrhagic telangiectasia

INTRODUCTION

Systemic bevacizumab is a novel targeted therapy for severe epistaxis and chronic gastrointestinal bleeding in hereditary haemorrhagic telangiectasia (HHT), but published data are very limited.

AIM

We conducted a survey-based study to characterize current treatment practices and physician-reported safety and effectiveness of systemic bevacizumab for bleeding in (HHT).

METHODS

A 27-item survey was sent to physician centre directors of 31 International HHT Centers of Excellence.

RESULTS

Response rate was 84%. Approximately half of centres had treated >10 HHT patients with systemic bevacizumab for chronic bleeding for a total of 291 patients treated. All centres utilize a 5 mg/kg dose for induction treatment and most administer six doses (range, 4-8) every 2 weeks. However, maintenance regimens varied considerably between centres. Bevacizumab was highly effective, with 86% reporting significant (>50%) improvement in GI bleeding and/or epistaxis and haemoglobin rise in most patients treated with bevacizumab; 52% reported haemoglobin normalization in most patients. All centres reported adverse event rates <30% and two-thirds of centres reported adverse event rates <10%. Discontinuation for adverse events or inefficacy was rare. Bleeding severity thresholds for initiation of bevacizumab were highly variable, and it is typically administered by haematologists (76% of centres). Two-thirds of centres reported obtaining insurance approval for bevacizumab for most or all patients but 48% reported difficulty in obtaining coverage.

CONCLUSION

Systemic bevacizumab is widely used to treat bleeding in HHT with excellent physician-reported effectiveness and safety. There is considerable variation in maintenance treatment practices and thresholds for initiation of bevacizumab among HHT centres.

Mobile Mitral and Aortic Valvular Masses in Patients With Hereditary Hemorrhagic Telangiectasia Receiving Intravenous Bevacizumab

Bevacizumab is now an emerging treatment option for severe hereditary hemorrhagic telangiectasia–related bleeding including epistaxis and gastrointestinal tract bleeding. The impact of long-term intravenous bevacizumab therapy on cardiac structure and function is unknown. We describe 3 patients receiving intravenous bevacizumab therapy for severe hereditary hemorrhagic telangiectasia–related bleeding who were found to have abnormal mobile masses on the mitral valve (n=2) and aortic valve (n=1). The clinical impact of these findings is unknown and requires further study.

Future treatments for hereditary hemorrhagic telangiectasia

Hereditary Hemorrhagic Telangiectasia (HHT), also known as Rendu-Osler syndrome, is a genetic vascular disorder affecting 1 in 5000–8000 individuals worldwide. This rare disease is characterized by various vascular defects including epistaxis, blood vessel dilations (telangiectasia) and arteriovenous malformations (AVM) in several organs. About 90% of the cases are associated with heterozygous mutations of ACVRL1 or ENG genes, that respectively encode a bone morphogenetic protein receptor (activin receptor-like kinase 1, ALK1) and a co-receptor named endoglin. Less frequent mutations found in the remaining 10% of patients also affect the gene SMAD4 which is part of the transcriptional complex directly activated by this pathway. Presently, the therapeutic treatments for HHT are intended to reduce the symptoms of the disease. However, recent progress has been made using drugs that target VEGF (vascular endothelial growth factor) and the angiogenic pathway with the use of bevacizumab (anti-VEGF antibody). Furthermore, several exciting high-throughput screenings and preclinical studies have identified new molecular targets directly related to the signaling pathways affected in the disease. These include FKBP12, PI3-kinase and angiopoietin-2. This review aims at reporting these recent developments that should soon allow a better care of HHT patients.

ACG Clinical Guideline: Disorders of the Hepatic and Mesenteric Circulation

Disorders of the mesenteric, portal, and hepatic veins and mesenteric and hepatic arteries have important clinical consequences and may lead to acute liver failure, chronic liver disease, noncirrhotic portal hypertension, cirrhosis, and hepatocellular carcinoma. Although literature in the field of vascular liver disorders is scant, these disorders are common in clinical practice, and general practitioners, gastroenterologists, and hepatologists may benefit from expert guidance and recommendations for management of these conditions. These guidelines represent the official practice recommendations of the American College of Gastroenterology. Key concept statements based on author expert opinion and review of literature and specific recommendations based on PICO/GRADE analysis have been developed to aid in the management of vascular liver disorders. These recommendations and guidelines should be tailored to individual patients and circumstances in routine clinical practice.

Gastrointestinal Bleeding in Patients with Hereditary Hemorrhagic Telangiectasia: Risk Factors and Endoscopic Findings

Background: We aimed to describe risk factors for gastrointestinal (GI) bleeding and endoscopic findings in patients with hereditary hemorrhagic telangiectasia (HHT). Methods: This is a prospective study from a referral HHT unit. Endoscopic tests were performed when there was suspicion of GI bleeding, and patients were divided as follows: with, without, and with unsuspected GI involvement. Results: 67 (27.9%) patients with, 28 (11.7%) patients without, and 145 (60.4%) with unsuspected GI involvement were included. Age, tobacco use, endoglin (ENG) mutation, and hemoglobin were associated with GI involvement. Telangiectases were mostly in the stomach and duodenum, but 18.5% of patients with normal esophagogastroduodenoscopy (EGD) had GI involvement in video capsule endoscopy (VCE). Telangiectases ≤ 3 mm and ≤10 per location were most common. Among patients with GI disease, those with hemoglobin < 8 g/dL or transfusion requirements (65.7%) were older and had higher epistaxis severity score (ESS) and larger telangiectases (>3 mm). After a mean follow-up of 34.2 months, patients with GI involvement required more transfusions and more emergency department and hospital admissions, with no differences in mortality. Conclusions: Risk factors for GI involvement have been identified. Patients with GI involvement and severe anemia had larger telangiectases and higher ESS. VCE should be considered in patients with suspicion of GI bleeding, even if EGD is normal.

Vascular malformations syndromes: an update

PURPOSE OF REVIEW

To provide an update of vascular malformation syndromes by reviewing the most recent articles on the topic and following the new International Society for the Study of Vascular Anomalies (ISSVA) 2018 classification.

RECENT FINDINGS

This review discusses the main features and diagnostic approaches of the vascular malformation syndromes, the new genetic findings and the new therapeutic strategies developed in recent months.

SUMMARY

Some vascular malformations can be associated with other anomalies, such as tissue overgrowth. PIK3CA-related overgrowth spectrum (PROS) is a group of rare genetic disorders with asymmetric overgrowth caused by somatic mosaic mutations in PI3K-AKT-mTOR pathway that encompass a heterogeneous group of rare disorder that are associated with the appearance of overgrowth. CLOVES syndrome and Klippel-Trénaunay syndrome are PROS disease. Proteus syndrome is an overgrowth syndrome caused by a somatic activating mutation in AKT1. CLOVES, Klippel-Trénaunay and Proteus syndromes are associated with high risk of thrombosis and pulmonary embolism. Hereditary hemorrhagic telangiectasia is an autosomic dominant disorder characterized by the presence of arteriovenous malformations. New therapeutic strategies with bevacizumab and thalidomide have been employed with promising results.

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

Background

Systemic bevacizumab is a novel targeted anti-angiogenic therapy for high-output cardiac failure (HOCF) in hereditary hemorrhagic telangiectasia (HHT) but published data is limited. This survey-based study measured physician-reported safety, effectiveness and current treatment practices for systemic bevacizumab in HHT-HOCF.

Methods

A 27-item survey was sent to center directors of 31 international HHT Centers of Excellence.

Results

Response rate was 74% with centers reporting 150 total patients receiving systemic bevacizumab for HHT-HOCF. Approximately two-thirds of centers had treated ≥5 patients. All centers utilize a 5 mg/kg dose for induction treatment and most administer 6 doses (range, 4–6) every 2 weeks, although maintenance regimens varied considerably. Center directors reported bevacizumab to be effective, with 55% reporting significant improvement in cardiac index and HOCF symptoms in most patients treated with bevacizumab, although normalization of cardiac parameters was uncommon. Adverse events were uncommon with three-quarters of centers reporting adverse event rates < 10%. Discontinuation for adverse events or ineffectiveness was rare. Bevacizumab was typically administered by hematologists and pulmonologists (50 and 39% of centers, respectively), with highly variable thresholds for initiation. Although half the centers reported difficulty with the insurance approval process, 70% of centers were ultimately able to obtain coverage for most or all of their patients.

Conclusions

Systemic bevacizumab is a widely-used therapy for HHT-HOCF with reasonable safety and effectiveness. HHT centers appear to vary considerably in maintenance treatment practices and disease severity thresholds for initiation of bevacizumab in HHT-related HOCF.

Safety of direct oral anticoagulants in patients with hereditary hemorrhagic telangiectasia

Background

Hereditary hemorrhagic telangiectasia (HHT) is a rare vascular dysplasia resulting in visceral arteriovenous malformations and smaller mucocutaneous telangiectasia. Most patients experience recurrent nosebleeds and become anemic without iron supplementation. However, thousands may require anticoagulation for conditions such as venous thromboembolism and/or atrial fibrillation. Over decades, tolerance data has been published for almost 200 HHT-affected users of warfarin and heparins, but there are no published data for the newer direct oral anticoagulants (DOACs) in HHT.

Methods

To provide such data, a retrospective audit was conducted across the eight HHT centres of the European Reference Network for Rare Multisystemic Vascular Diseases (VASCERN), in Denmark, France, Germany, Italy, the Netherlands and the UK.

Results

Although HHT Centres had not specifically recommended the use of DOACs, 32 treatment episodes had been initiated by other clinicians in 28 patients reviewed at the Centres, at median age 65 years (range 30–84). Indications were for atrial fibrillation (16 treatment episodes) and venous thromboembolism (16 episodes). The 32 treatment episodes used Apixaban (n = 15), Rivaroxaban (n = 14), and Dabigatran (n = 3). HHT nosebleeds increased in severity in 24/32 treatment episodes (75%), leading to treatment discontinuation in 11 (34.4%). Treatment discontinuation was required for 4/15 (26.7%) Apixaban episodes and 7/14 (50%) Rivaroxaban episodes. By a 4 point scale of increasing severity, there was a trend for Rivaroxaban to be associated with a greater bleeding risk both including and excluding patients who had used more than one agent (age-adjusted coefficients 0.61 (95% confidence intervals 0.11, 1.20) and 0.74 (95% confidence intervals 0.12, 1.36) respectively. Associations were maintained after adjustment for gender and treatment indication. Extreme hemorrhagic responses, worse than anything experienced previously, with individual nosebleeds lasting hours requiring hospital admissions, blood transfusions and in all cases treatment discontinuation, occurred in 5/14 (35.7%) Rivaroxaban episodes compared to 3/15 (20%) Apixaban episodes and published rates of ~ 5% for warfarin and heparin.

Conclusions

Currently, conventional heparin and warfarin remain first choice anticoagulants in HHT. If newer anticoagulants are considered, although study numbers are small, at this stage Apixaban appears to be associated with lesser bleeding risk than Rivaroxaban.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1179-1) contains supplementary material, which is available to authorized users.

Natural history of patients with venous thromboembolism and hereditary hemorrhagic telangiectasia. Findings from the RIETE registry

Background

Limited data exist about the clinical presentation, ideal therapy and outcomes of patients with hereditary hemorrhagic telangiectasia (HHT) who develop venous thromboembolism (VTE).

Methods

We used the data in the RIETE Registry to assess the clinical characteristics, therapeutic approaches and clinical outcomes during the course of anticoagulant therapy in patients with HHT according to initial presentation as pulmonary embolism (PE) or deep venous thrombosis (DVT).

Results

Of 51,375 patients with acute VTE enrolled in RIETE from February 2009 to January 2019, 23 (0.04%) had HHT: 14 (61%) initially presented with PE and 9 (39%) with DVT alone. Almost half (47.8%) of the patients with VTE had a risk factor for VTE. Most PE and DVT patients received low-molecular-weight heparin for initial (71 and 100%, respectively) and long-term therapy (54 and 67%, respectively). During anticoagulation for VTE, the rate of bleeding events (major 2, non-major 6) far outweighed the rate of VTE recurrences (recurrent DVT 1): 50.1 bleeds per 100 patient-years (95%CI: 21.6-98.7) vs. 6.26 recurrences (95%CI: 0.31–30.9; p = 0.020). One major and three non-major bleeding were epistaxis. No patient died of bleeding. One patient died shortly after being diagnosed with acute PE.

Conclusions

During anticoagulation for VTE in HHT patients, there were more bleeding events than VTE recurrences. Most bleeding episodes were non-major epistaxis.

Pericytes in Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is a genetic disorder characterized by multi-systemic vascular dysplasia affecting 1 in 5000 people worldwide. Individuals with HHT suffer from many complications including nose and gastrointestinal bleeding, anemia, iron deficiency, stroke, abscess, and high-output heart failure. Identification of the causative gene mutations and the generation of animal models have revealed that decreased transforming growth factor-β (TGF-β)/bone morphogenetic protein (BMP) signaling and increased vascular endothelial growth factor (VEGF) signaling activity in endothelial cells are responsible for the development of the vascular malformations in HHT. Perturbations in these key pathways are thought to lead to endothelial cell activation resulting in mural cell disengagement from the endothelium. This initial instability state causes the blood vessels to response inadequately when they are exposed to angiogenic triggers resulting in excessive blood vessel growth and the formation of vascular abnormalities that are prone to bleeding. Drugs promoting blood vessel stability have been reported as effective in preclinical models and in clinical trials indicating possible interventional targets based on a normalization approach for treating HHT. Here, we will review how disturbed TGF-β and VEGF signaling relates to blood vessel destabilization and HHT development and will discuss therapeutic opportunities based on the concept of vessel normalization to treat HHT.