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

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.

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.

A precision medicine approach to hereditary hemorrhagic telangiectasia and complex vascular anomalies

Vascular anomalies represent a diverse group of disorders classified broadly as malformations or tumors and include the second most common hereditary bleeding disorder worldwide, hereditary hemorrhagic telangiectasia (HHT). Patients with HHT and other vascular anomalies suffer morbid consequences of these diseases, including bleeding, thrombosis, anemia, localized intravascular coagulation, tissue overgrowth, infections, and other complications. The International Society for the Study of Vascular Anomalies (ISSVA) has developed a standard classification of these disorders, creating a uniform approach to their diagnosis, and the treatments for vascular anomalies are rapidly evolving. Recent discoveries have elucidated the molecular basis of a number of common and uncommon vascular anomalies. HHT occurs due to mutations in the transforming growth factor beta (TGF-β) pathway, resulting in vascular endothelial growth factor excess. Complex vascular anomalies including Klippel-Trénaunay syndrome (KTS) and arteriovenous malformation (AVM) may occur due to mutations in the PI3K/AKT/mTOR and RAS/MAPK/MEK pathways. The discovery of the pathophysiologic mechanisms driving these diseases has led to improved phenotype-genotype correlation and the opportunity to target molecular pathways with medical therapies. Therefore, targeted agents have quickly become a standard of care in the treatment of vascular disorders (particularly HHT). Herein, we provide a case-based approach to the use of antiangiogenic therapies including bevacizumab and pazopanib for the treatment of bleeding in HHT and the use of mammalian target of rapamycin (sirolimus), PIK3CA (alpelisib), and MEK (trametinib) inhibitors in the treatment of complex vascular anomalies.

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.

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.