Efficacy of TIMOLOL nasal spray as a treatment for epistaxis in hereditary hemorrhagic telangiectasia. A double-blind, randomized, placebo-controlled trial

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..

Cost-effectiveness of bevacizumab therapy in the care of patients with hereditary hemorrhagic telangiectasia

ABSTRACT

No US Food and Drug Administration- or European Medicines Agency-approved therapies exist for bleeding due to hereditary hemorrhagic telangiectasia (HHT), the second-most common inherited bleeding disorder worldwide. The current standard of care (SOC) includes iron and red cell supplementation, alongside the necessary hemostatic procedures, none of which target underlying disease pathogenesis. Recent evidence has demonstrated that bleeding pathophysiology is amenable to systemic antiangiogenic therapy with the anti-vascular endothelial growth factor bevacizumab. Despite its high cost, the addition of longitudinal bevacizumab to the current SOC may reduce overall health care resource use and improve patient quality of life. We conducted, to our knowledge, the first cost-effectiveness analysis of IV bevacizumab in patients with HHT with the moderate-to-severe phenotype, comparing bevacizumab added to SOC vs SOC alone. The primary outcome was the incremental net monetary benefit (iNMB) reported over a lifetime time horizon and across accepted willingness-to-pay thresholds, in US dollar per quality-adjusted life year (QALY). Bevacizumab therapy accrued 9.3 QALYs while generating $428 000 in costs, compared with 8.3 QALYs and $699 000 in costs accrued in the SOC strategy. The iNMB of bevacizumab therapy vs the SOC was $433 000. No parameter variation and no scenario analysis, including choice of iron supplementation product, changed the outcome of bevacizumab being a cost-saving strategy. Bevacizumab therapy also saved patients an average of 133 hours spent receiving HHT-specific care per year of life. In probabilistic sensitivity analysis, bevacizumab was favored in 100% of all 10 000 Monte Carlo iterations across base-case and all scenario analyses. Bevacizumab should be considered for more favorable formulary placement in the care of patients with moderate-to-severe HHT.

Understanding hereditary hemorrhagic telangiectasia: From genetic anomalies to systemic manifestations, quality of life, and epistaxis management-Exploring the otolaryngologist's integral role

Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Rendu-Weber syndrome, is a rare autosomal dominant disorder characterized by vascular malformations. This comprehensive review aimed to provide an overview and summarize various aspects of HHT, including the genetic abnormalities, complications associated with visceral arteriovenous malformations (AVMs), prognosis of HHT, quality of life (QOL), and treatment of epistaxis. In addition, this review highlights the challenges in diagnosing HHT and emphasizes the critical role of otolaryngologists in the early detection of HHT. Otolaryngologists can refer patients with refractory epistaxis for AVM screening to expedite intervention. Mutation of the genes involved in the transforming growth factor-β signaling pathway leads to the incidence of HHT, resulting in the formation of abnormal blood vessel formation. These vascular malformations commonly manifest as telangiectasia on the skin and mucous membranes; however, epistaxis remains the hallmark symptom of HHT. The impact of HHT goes beyond the visible symptoms and often includes the formation of life-threatening visceral AVMs in the lungs, liver, and brain. The prognosis of patients with HHT is closely related to the development of these complications, necessitating timely diagnosis and intervention. Refractory epistaxis diminishes the QOL of patients with HHT. The management of epistaxis ranges from conservative measures to advanced interventions such as prevention, conservative treatments, ablation, surgical procedures, and the administration of anti-angiogenic agents. However, effective management requires a multidisciplinary approach. The diagnosis of HHT remains challenging due to its variable presentation and lack of awareness among physicians. This review highlights the importance of reducing the duration between symptom onset and diagnosis. Otolaryngologists who are experienced in the management of refractory epistaxis can aid in identifying potential cases of HHT. They can facilitate the initiation of screening for visceral AVMs via prompt recognition of the signs and symptoms of HHT, contributing to improved patient outcomes. Early detection and intervention through screening can extend the life expectancy of patients with HHT to levels comparable with that of the general population. In conclusion, this review provides insight into various aspects of HHT and emphasizes the importance of timely diagnosis and intervention in the mitigation of the potentially life-threatening complications associated with this disorder. Otolaryngologists play a critical role in this process, serving as gatekeepers to the identification of cases of HHT and implementation of appropriate screening and management pathways, thereby improving the life expectancy and QOL of patients.

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.

Treatments of Epistaxis in Hereditary Hemorrhagic Telangiectasia: Systematic Review and Network Meta-Analysis

PURPOSE OF REVIEW

To analyze and compare the effects of epistaxis treatments for Hereditary Hemorrhagic Telangiectasia (HHT) patients.

RECENT FINDINGS

Of total of 21 randomized controlled trials (RCT), the data from 15 RCTs (697 patients, 7 treatments: timolol, propranolol, bevacizumab, doxycycline, tacrolimus, estriol/estradiol, and tranexamic acid) were pooled for the meta-analyses while the other 6 studies (treatments: electrosurgical plasma coagulation, KTP laser, postoperative packing, tamoxifen, sclerosing agent, and estriol) were reviewed qualitatively. When compared to placebo, propranolol offered the most improved epistaxis severity score, mean difference (MD), -1.68, 95% confidence interval (95%CI) [-2.80, -0.56] followed by timolol, MD -0.40, 95%CI [-0.79, -0.02]. Tranexamic acid significantly reduced the epistaxis frequency, MD -1.93, 95%CI [-3.58, -0.28]. Other treatments had indifferent effects to placebo. Qualitative analysis highlighted the benefits of tamoxifen and estriol. The adverse events of tranexamic acid, tacrolimus, propranolol, and estradiol were significantly reported. Propranolol, timolol, tranexamic acid, tamoxifen, and estriol were effective treatments which offered benefits to HHT patients in epistaxis management. Adverse events of tranexamic acid, tacrolimus, propranolol, and estradiol should be concerned.

The Use of Beta-Blockers in Hereditary Hemorrhagic Telangiectasia-Related Epistaxis: A Systematic Review

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disease affecting 1 in 5000 individuals. Epistaxis is seen in more than 90% of patients with HHT. Severe recurrent epistaxis can significantly decrease quality of life and may be resistant to standard treatment measures. Dysregulation of angiogenesis has been shown to cause the proliferation of abnormal blood vessels. As such, antiangiogenic treatments have been investigated including beta-blockers.

OBJECTIVE

A systematic review of the efficacy of beta-blockers in topical treatment of epistaxis in patients with HHT based on epistaxis duration, frequency, and severity.

METHODS

A systematic search was performed using the PubMed, Embase via Ovid, and Cochrane databases. The Preferred Items for Systematic Reviews and Meta-Analyses guidelines were followed. Studies that measured the efficacy of beta-blocker treatment of epistaxis in patients with HHT were included for qualitative analysis.

RESULTS

Five studies (3 randomized controlled trials and 2 case series) with a total of 132 patients were included. Administration (systemically or topically via a spray or gel) of timolol and propranolol showed mixed evidence of improvement in epistaxis frequency, severity, and duration when compared with control groups. The evidence for propranolol appears more promising than timolol.

CONCLUSION

There are significant limitations in the included studies, and further investigation with larger longitudinal or randomized prospective trials is recommended. The available evidence suggests that beta-blocker treatment may have a positive effect on HHT-related epistaxis.

TIMolol Nasal Spray as a Treatment for Epistaxis in Hereditary Hemorrhagic Telangiectasia (TIM-HHT)—A Prospective, Randomized, Double-Blind, Controlled, Cross-Over Trial

To date, there is no approved local therapeutic agent for the treatment of epistaxis due to hereditary hemorrhagic telangiectasia (HHT). Several case reports suggest the topical use of timolol. This monocentric, prospective, randomized, placebo-controlled, double-blinded, cross-over study investigated whether the effectiveness of the standard treatment with a pulsed diode laser can be increased by also using timolol nasal spray. The primary outcome was severity of epistaxis after three months, while the main secondary outcome was severity of epistaxis and subjective satisfaction after one month. Twenty patients were allocated and treated, of which 18 patients completed both 3-month treatment sequences. Timolol was well tolerated by all patients. Epistaxis Severity Score after three months, the primary outcome measure, showed a beneficial, but statistically nonsignificant (p = 0.084), effect of additional timolol application. Epistaxis Severity Score (p = 0.010) and patients’ satisfaction with their nosebleeds after one month (p = 0.050) showed statistically significant benefits. This placebo-controlled, randomized trial provides some evidence that timolol nasal spray positively impacts epistaxis severity and subjective satisfaction in HHT patients when additively applied to standard laser therapy after one month. However, the effect of timolol was observed to diminish over time. Trials with larger sample sizes are warranted to confirm these findings.

TIMolol nasal spray as a treatment for epistaxis in hereditary hemorrhagic telangiectasia (HHT) - study protocol of the prospective, randomized, double-blind, controlled cross-over TIM-HHT trial

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT) is an inherited orphan disease, in which the absence of capillary beds between arterioles and venules lead to arteriovenous shunts. Epistaxis is the core symptom. Several case reports have described the nonselective beta-adrenergic receptor antagonist timolol as a successful treatment method of nosebleeds due in HHT patients.

OBJECTIVE

TIM-HHT is a single-site, prospective, randomized, placebo-controlled, double-blind, cross-over study to investigate whether the efficacy of standard laser treatment of epistaxis in HHT patients can be increased by the additional use of timolol nasal spray (1 mg/d).

METHODS

Twenty patients will be randomly allocated to one of two treatment sequences. Primary outcome is the severity of epistaxis determined by the Epistaxis Severity Score (ESS). Secondary outcomes are subjective satisfaction, quality of life, as well as the hemoglobin, ferritin, and transferrin levels of the participating patients. Safety outcome is assessed by means of pulse, blood pressure, and adverse events.

CONCLUSION

TIM-HHT will evaluate the efficacy and safety of timolol as an additional treatment of epistaxis in HHT patients in a three-month trial period. Benzalkonium chloride is used as a placebo, which has no documented positive effect on the nasal mucosa and hence on epistaxis in HHT patients (in contrast to saline).

TRIAL REGISTRATION

German Clinical Trials Register (DRKS), DRKS00020994. Registered on 10 March 2020.

Improvement in epistaxis management: the experience of a dedicated hereditary haemorrhagic telangiectasia clinic

BACKGROUND

Hereditary haemorrhagic telangiectasia (HHT) is a rare genetic vascular disorder which is characterised by the development of arteriovenous malformations and telangiectasias. A key clinical manifestation is recurrent epistaxis. This study examined the impact of a dedicated HHT clinic in a major Australian tertiary hospital on epistaxis symptoms and subjective quality of life.

METHODS

A multidisciplinary HHT clinic was established in 2015. All patients satisfied either genetic diagnosis or fulfilled Curacao criteria. A protocol based clinical assessment was performed and a standardised treatment regimen was implemented. Patients completed quality of life and epistaxis severity score (ESS) questionnaires at each review.

RESULTS

Participants of the dedicated clinic included 21 females (58.3%) and 15 males (41.7%), with a mean age of 49.0 ± 24.0 years. The ACVRL1 variant was the most common (n = 20, 55.6%). A statistically significant reduction in epistaxis severity was noted between the baseline and second review (P = 0.02) and was maintained to the third visit (P = 0.015). Patients older than 50 years demonstrate a consistently higher ESS than those less than 50 years old (P = 0.03). This trend is noted throughout the follow up period with the dedicated clinic.

CONCLUSION

The introduction of a multidisciplinary, dedicated HHT clinic to provide enhanced assessment, monitored treatment regimen and greater access to care, resulted in improvement in the management of epistaxis and quality of life in these patients.

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.

Efficacy of Timolol in a Novel Intranasal Thermosensitive Gel for Hereditary Hemorrhagic Telangiectasia-Associated Epistaxis: A Randomized Clinical Trial

Importance

Other than nasal moisturizers, no standard-of-care medical therapy exists for epistaxis in hereditary hemorrhagic telangiectasia (HHT). With epistaxis as the greatest cause of morbidity in patients with HHT, there is a need to identify effective topical therapies.

Objective

To determine the efficacy and safety of an intranasal timolol thermosensitive gel vs placebo thermosensitive gel in treating HHT-associated epistaxis.

Design, Setting, and Participants

This double-blind, placebo-controlled randomized clinical trial was conducted from October 29, 2019, to May 20, 2020, at a tertiary care center. A total of 27 patients with HHT and moderate-to-severe epistaxis were recruited and included in this prespecified analysis: 14 in the timolol group and 13 in the placebo group. Inclusion criteria included (1) age 18 years or older, (2) clinical or genetic diagnosis of HHT, (3) screening Epistaxis Severity Score (ESS) of 4 or greater and 2 or more nosebleeds cumulatively lasting at least 5 minutes per week, (4) stable epistaxis pattern over the preceding 3 months, and (5) no change in epistaxis treatment or nasal hygiene regimen in the preceding month. Exclusion criteria included (1) contraindications to systemic β-blocker administration, (2) use of medications interacting with timolol, (3) use of antiangiogenic medications in the last month before recruitment, and (4) use of anticoagulants, antiplatelets, or fibrinolytic therapies within the last month.

Interventions

Novel thermosensitive intranasal timolol (0.1%) gel vs placebo thermosensitive gel applied twice daily to each nostril for 8 weeks.

Main Outcomes and Measures

The primary outcome was the median change in ESS and percentage of participants reaching the minimal clinically important difference in ESS. Secondary outcomes were changes in Clinical Global Impression-Severity and Clinical Global Impression-Improvement scores, Nasal Outcome Score for Epistaxis in Hereditary Hemorrhagic Telangiectasia, and hemoglobin level.

Results

Of 27 participants randomized (median [range] age, 55 [20-76] years; 14 women [52%]; 25 White [93%]), a total of 23 patients with HHT completed the primary outcome measure. Within the timolol gel and placebo gel groups, respectively, the median change (range) in ESS was 2.32 (0.22 to 5.97) vs 1.96 (-0.91 to 5.98), and 9 of 11 (82%) vs 9 of 12 (75%) participants experienced a clinically meaningful improvement in ESS. Twenty-two of the 23 participants (96%) reported improvement via the Clinical Global Impression-Improvement score, with 81% vs 58% of participants reporting reduced severity of epistaxis in the timolol vs placebo group, respectively. Of participants completing the Nasal Outcome Score for Epistaxis in HHT at follow-up visit, 7 of 10 (70%) in the timolol group achieved a clinically important difference vs 5 of 10 (50%) in the placebo group. There was no change in hemoglobin level between or within groups. Zero participants in the placebo group and 2 of 13 (15%) in the timolol group withdrew because of adverse events.

Conclusions and Relevance

Thermosensitive gel, alone or in combination with timolol, was highly effective in reducing HHT-associated epistaxis. The timolol group had greater improvement in epistaxis and quality of life than the placebo group, but effect estimates were imprecise, and no definitive conclusions on the superiority of timolol can be drawn. Physicians treating patients with HHT-associated epistaxis should consider a thermosensitive gel (with or without timolol) for their patients.

Trial Registration

ClinicalTrials.gov Identifier: NCT04139018.

[Hereditary hemorrhagic telangiectasia: symptoms and diagnostic latency]

OBJECTIVE

Patients with hereditary hemorrhagic Telangiectasia (HHT) suffer from a rare and systemic disease which is characterized by vascular malformations leading to a variety of different symptoms.

MATERIAL AND METHODS

A retrospective review of patients who were referred to our new HHT Center of Excellence (HHT COE) for evaluation and treatment between April 2014 and August 2019 was performed.

RESULTS

235 patients were treated at the West German HHT Center. 83 % of these were diagnosed with definite HHT (235/282, 83 %) and 9 % with possible HHT (26/282). The average latency between first manifestation and definite diagnosis of HHT was 18 years. Several initial symptoms were direct or indirect signs of bleeding (224/241, 93 %). In 83 % of the patients HHT was reported having caused their degree of disability. Older, female patients and those with severe epistaxis suffered from chronic iron deficiency anemia, took iron preparations (148/261, 57 %) and received 9 blood transfusions on average (± standard deviation: 41, minimum - maximum: 0-400, number of patients: 218). 10 % of all patients tolerated anticoagulant or antiplatelet agents. 74 % of patients with HHT used nasal creams/sprays/oils (177/238) and reported fewer bleedings compared to patients without nasal care (ESS: T-Test: 3.193; p = 0.003; anemia: Chi-square: 5.173; p = 0.023).

CONCLUSIONS

The diagnostic latency of HHT was almost two decades. Patients with HHT particularly suffered from recurrent epistaxis, which was mostly treated with nasal care and coagulative therapies. Antiplatelet or anticoagulant agents can be used in patients with HHT with caution if indicated.

Hereditary Haemorrhagic Telangiectasia, an Inherited Vascular Disorder in Need of Improved Evidence-Based Pharmaceutical Interventions

Hereditary haemorrhagic telangiectasia (HHT) is characterised by arteriovenous malformations (AVMs). These vascular abnormalities form when arteries and veins directly connect, bypassing the local capillary system. Large AVMs may occur in the lungs, liver and brain, increasing the risk of morbidity and mortality. Smaller AVMs, known as telangiectases, are prevalent on the skin and mucosal lining of the nose, mouth and gastrointestinal tract and are prone to haemorrhage. HHT is primarily associated with a reduction in endoglin (ENG) or ACVRL1 activity due to loss-of-function mutations. ENG and ACVRL1 transmembrane receptors are expressed on endothelial cells (ECs) and bind to circulating ligands BMP9 and BMP10 with high affinity. Ligand binding to the receptor complex leads to activation of the SMAD1/5/8 signalling pathway to regulate downstream gene expression. Various genetic animal models demonstrate that disruption of this pathway in ECs results in AVMs. The vascular abnormalities underlying AVM formation result from abnormal EC responses to angiogenic and haemodynamic cues, and include increased proliferation, reduced migration against the direction of blood flow and an increased EC footprint. There is growing evidence that targeting VEGF signalling has beneficial outcomes in HHT patients and in animal models of this disease. The anti-VEGF inhibitor bevacizumab reduces epistaxis and has a normalising effect on high cardiac output in HHT patients with hepatic AVMs. Blocking VEGF signalling also reduces vascular malformations in mouse models of HHT1 and HHT2. However, VEGF signalling is complex and drives numerous downstream pathways, and it is not yet clear which pathway (or combination of pathways) is critical to target. This review will consider the recent evidence gained from HHT clinical and preclinical studies that are increasing our understanding of HHT pathobiology and informing therapeutic strategies.

[Diagnostic Criteria and Treatment of Hereditary Hemorrhagic Telangiectasia]

Hereditary hemorrhagic telangiectasia (HHT; Osler-Weber-Rendu syndrome; Morbus Osler) represents a syndrome affecting capillary vessels, leading to arteriovenous shunting. With an average worldwide prevalence of 1:5.000-8.000 HHT is considered an orphan disease. Arteriovenous shunts involve predominantly the nasal mucosa, the intestine, lung, liver and central nervous system. Epistaxis is the primary and most bothersome complaint of patients with HHT. A multistage therapeutic concept includes nasal ointment, laser therapy under local anesthesia and surgery under general anesthesia, as well as drug therapies. In addition, screening to determine affection of internal organs is carried out. Lesions that require therapy should be treated in an interdisciplinary setting. Treatment of lesions of the skin, oral and gastrointestinal mucosa and liver is carried out in regard to patients' symptoms, whereas vascular malformations of the lung and brain might need treatment without being symptomatic, due to possible life-threatening complications.

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.