Efficacy and Safety of Tacrolimus as Treatment for Bleeding Caused by Hereditary Hemorrhagic Telangiectasia: An Open-Label, Pilot Study

Hereditary Hemorrhagic Telangiectasia: On the Brink of a New Treatment Era?

Hereditary hemorrhagic telangiectasia (HHT) is an inherited vascular disorder with highly variable penetrance, affecting up to 1 in 5,000 individuals. It is characterized by the presence of abnormal blood vessels that can lead to excessive bleeding-most frequently recurrent nosebleeds (epistaxis), skin and mucosal telangiectasias (small, dilated blood vessels), as well as arteriovenous malformations (AVMs) that can form in various organs, particularly the lungs, liver, and brain. HHT is caused by loss-of-function mutations in the BMP9-10/ENG/ALK1/SMAD4 signaling pathway, an important mediator of vascular quiescence. HHT possesses significant challenges for affected individuals, as the complications can range from mild to life-threatening events, depending on the severity and location of the vascular abnormalities. Despite this bleeding disorder being not uncommon, nowadays no specific treatment is as yet available for HHT and most current therapies include repurposed drugs. The aim of this review was to show therapeutic advances on the basis of recent promising clinical trials for HHT.

Hereditary haemorrhagic telangiectasia

Hereditary haemorrhagic telangiectasia (HHT) is a vascular dysplasia inherited as an autosomal dominant trait and caused by loss-of-function pathogenic variants in genes encoding proteins of the BMP signalling pathway. Up to 90% of disease-causal variants are observed in ENG and ACVRL1, with SMAD4 and GDF2 less frequently responsible for HHT. In adults, the most frequent HHT manifestations relate to iron deficiency and anaemia owing to recurrent epistaxis (nosebleeds) or bleeding from gastrointestinal telangiectases. Arteriovenous malformations (AVMs) in the lungs, liver and the central nervous system cause additional major complications and often complex symptoms, primarily due to vascular shunting, which is right-to-left through pulmonary AVMs (causing ischaemic stroke or cerebral abscess) and left-to-right through systemic AVMs (causing high cardiac output). Children usually experience isolated epistaxis; in rare cases, childhood complications occur from large AVMs in the lungs or central nervous system. Management goals encompass control of epistaxis and intestinal bleeding from telangiectases, screening for and treatment of iron deficiency (with or without anaemia) and AVMs, genetic counselling and evaluation of at-risk family members. Novel therapeutics, such as systemic antiangiogenic therapies, are actively being investigated. Although HHT is associated with increased morbidity, the appropriate screening and treatment of visceral AVMs, and the effective management of bleeding and anaemia, improves quality of life and overall survival.

Hereditary Hemorrhagic Telangiectasia (Osler's Disease): Systemic, Interdisciplinary, Relatively Common—and Often Missed

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT, Rendu- Osler-Weber disease, or Osler's disease for short) is a systemic disease that can severely impair the quality of life and that requires interdisciplinary treatment. Among rare diseases, it is relatively common, with a prevalence of approximately 1/5000.

METHODS

This review is based on publications retrieved by a selective literature search, including the two international guidelines on clinically relevant aspects of HHT.

RESULTS

On average, about two decades elapse between the initial symptoms and the diagnosis of HHT. 95% of patients have nosebleeds; these usually begin before age 20 but can occur at any time, from infancy to old age. The diagnosis is usually made on clinical grounds on the basis of the characteristic telangiectases, a positive family history, and possible involvement of the gastrointestinal tract, lungs, liver, and brain. Nosebleeds can sometimes be reduced by outpatient measures including counseling on keeping the nose moist (expert consensus), self-application of a nasal packing (which improves the quality of life, according to an online survey), and the prescription of tranexamic acid (reduction of nosebleeds from 17.3% [5.5; 27.6] to 54%). In particular, screening (expert consensus) for pulmonary vascular malformations (frequency 10-50%) can prevent many adverse outcomes. If pulmonary vascular malformations cannot be ruled out, antibiotic prophylaxis is recommended before medical procedures that can cause bacteremia (expert consensus).

CONCLUSION

Broad awareness of the condition, early diagnosis, and interdisciplinary treatment improve the quality of life and ultimate outcome of persons with HHT. Nevertheless, there are few options supported by good evidence for the appropriate treatment of this rare, often serious disease..

Cracking the code of the cardiovascular enigma: hPSC-derived endothelial cells unveil the secrets of endothelial dysfunction

Endothelial dysfunction is a central contributor to the development of most cardiovascular diseases and is characterised by the reduced synthesis or bioavailability of the vasodilator nitric oxide together with other abnormalities such as inflammation, senescence, and oxidative stress. The use of patient-specific and genome-edited human pluripotent stem cell-derived endothelial cells (hPSC-ECs) has shed novel insights into the role of endothelial dysfunction in cardiovascular diseases with strong genetic components such as genetic cardiomyopathies and pulmonary arterial hypertension. However, their utility in studying complex multifactorial diseases such as atherosclerosis, metabolic syndrome and heart failure poses notable challenges. In this review, we provide an overview of the different methods used to generate and characterise hPSC-ECs before comprehensively assessing their effectiveness in cardiovascular disease modelling and high-throughput drug screening. Furthermore, we explore current obstacles that will need to be overcome to unleash the full potential of hPSC-ECs in facilitating patient-specific precision medicine. Addressing these challenges holds great promise in advancing our understanding of intricate cardiovascular diseases and in tailoring personalised therapeutic strategies.

Hereditary hemorrhagic telangiectasia: from signaling insights to therapeutic advances

Hereditary hemorrhagic telangiectsia (HHT) is an inherited vascular disorder with highly variable expressivity, affecting up to 1 in 5,000 individuals. This disease is characterized by small arteriovenous malformations (AVMs) in mucocutaneous areas (telangiectases) and larger visceral AVMs in the lungs, liver, and brain. HHT is caused by loss-of-function mutations in the BMP9-10/ENG/ALK1/SMAD4 signaling pathway. This Review presents up-to-date insights on this mutated signaling pathway and its crosstalk with proangiogenic pathways, in particular the VEGF pathway, that has allowed the repurposing of new drugs for HHT treatment. However, despite the substantial benefits of these new treatments in terms of alleviating symptom severity, this not-so-uncommon bleeding disorder still currently lacks any FDA- or European Medicines Agency-approved (EMA-approved) therapies.

Executive summary of the 14th HHT international scientific conference

Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal dominant vascular disorder characterized by small, dilated clustered vessels (telangiectasias) and by larger visceral arteriovenous malformations (AVMs), which directly connect the feeding arteries with the draining veins. These lesions are fragile, prone to rupture, and lead to recurrent epistaxis and/or internal hemorrhage among other complications. Germline heterozygous loss-of-function (LOF) mutations in Bone Morphogenic Protein 9 (BMP9) and BMP10 signaling pathway genes (endoglin-ENG, activin like kinase 1 ACVRL1 aka ALK1, and SMAD4) cause different subtypes of HHT (HHT1, HHT2 and HHT-juvenile polyposis (JP)) and have a worldwide combined incidence of about 1:5000. Expert clinicians and international scientists gathered in Cascais, Portugal from September 29th to October 2nd, 2022 to present the latest scientific research in the HHT field and novel treatment strategies for people living with HHT. During the largest HHT scientific conference yet, participants included 293 in person and 46 virtually. An impressive 209 abstracts were accepted to the meeting and 59 were selected for oral presentations. The remaining 150 abstracts were presented during judged poster sessions. This review article summarizes the basic and clinical abstracts selected as oral presentations with their new observations and discoveries as well as surrounding discussion and debate. Two discussion-based workshops were also held during the conference, each focusing on mechanisms and clinical perspectives in either AVM formation and progression or current and future therapies for HHT. Our hope is that this paper will represent the current progress and the remaining unanswered questions surrounding HHT, in order to serve as an update for those within the field and an invitation to those scientists and clinicians as yet outside of the field of HHT.

Current guidelines for diagnosis and management of hepatic involvement in hereditary hemorrhagic teleangiectasia

Hereditary hemorrhagic teleangiectasia (HHT), also known as Rendu-Osler-Weber syndrome, is the most common cause of hepatic vascular malformations in adults. Different vascular shunts (arteriovenous, arterioportal or portovenous) lead to different clinical manifestations. Even though no hepatic-related symptoms are reported in the majority of cases, the severity of liver disease could lead to refractory medical conditions, in some cases requiring liver transplantation. The aim of this manuscript is to provide an updated overview of the current evidence regarding the diagnosis and treatment of HHT liver involvement and liver-related complications.

[Hereditary hemorrhagic telangiectasia]

Hereditary hemorrhagic telangiectasia, also known as Rendu-Osler - Weber disease, is a rare, autosomal dominant vascular disease, with prevalence of 1/5,000. The condition is characterized by muco-cutaneous telangiectasias, which are responsible for a hemorrhagic syndrome of variable severity, as well as arteriovenous malformations (AVMs) appearing in the lungs, the liver, and the nervous system. They can be the source of shunts, which may be associated with high morbidity (neurological ischemic stroke, brain abscess, high-output heart failure, biliary ischemia…). It is therefore crucial to establish a clinical diagnosis using the Curaçao criteria or molecular diagnosis based on genetic analysis of the ENG, ACVRL1, SMAD4 and GDF2 genes. In most cases, multidisciplinary management allows patients to have normal life expectancy. Advances in interventional radiology and better understanding of the pathophysiology of angiogenesis have resulted in improved therapeutic management. Anti-angiogenic treatments, such as bevacizumab (BVZ, an anti-VEGF antibody), have proven to be effective in cases involving bleeding complications and severe liver damage with cardiac repercussions. Other anti-angiogenic agents are currently being investigated, including tyrosine kinase inhibitors.