Diagnostic criteria for hereditary hemorrhagic telangiectasia (Rendu-Osler-Weber syndrome)

Impact of SARS-CoV-2 infection in patients with hereditary hemorrhagic telangiectasia: epidemiological and clinical data from the comprehensive Italian retrospective multicenter study

Rare Disease patients manifested high concern regarding the possible increased risk of severe outcomes and worsening of disease-specific clinical manifestation due to the impact of COVID-19. Our aim was to assess the prevalence, outcomes, and impact of COVID-19 in patients with a rare disease such as Hereditary Hemorrhagic Telangiectasia (HHT) in Italian population. A nationwide, multicentric, cross-sectional observational study was conducted on patients with HHT from five Italian HHT centers by online survey. The association between COVID-19-related signs and symptoms and nosebleeds worsening, the impact of personal protective equipment on nosebleeds pattern, and the relationship between the presence of visceral AVMs and severe outcomes were analyzed. Out of 605 total survey responses and eligible for analysis, 107 cases of COVID-19 were reported. A mild-course COVID-19 disease, not requiring hospitalization, was observed in 90.7% of patients, while the remaining eight cases needed hospitalization, two of them requiring intensive-care access. No fatal outcome was recorded and 79.3% of patients reported a complete recovery. No difference in infection risk and outcome between HHT patients and general population was evidenced. No significative interference of COVID-19 on HHT-related bleeding was found. The majority of patients received COVID-19 vaccination, with relevant impact on symptoms and need for hospitalization in case of infection. COVID-19 in HHT patients had an infection profile similar to the general population. COVID-19 course and outcome were independent from any specific HHT-related clinical features. Moreover, COVID-19 and anti-SARS-CoV-2 measures did not seem to affect significantly HHT-related bleeding profile.

Dose - response relationship of bevacizumab in hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT), a genetic vascular disorder associated with epistaxis and hepatic shunts, is responsible for high-output cardiac failure in rare cases. Bevacizumab, which targets vascular endothelial growth factor, was shown to decrease both cardiac index (CI) and epistaxis duration in HHT patients with severe liver involvement. The relationship between its serum concentration and change in both CI and epistaxis duration was investigated to design the bevacizumab maintenance dosing regimen of future therapeutic studies. Twenty-five HHT patients with dyspnea and high CI were included in a prospective non-comparative study. They received bevacizumab at a dose of 5 mg/kg per infusion every 14 days for a total of 6 injections. The relationships between bevacizumab serum concentration and both CI and epistaxis duration were described using transit compartments and direct inhibition pharmacokinetic-pharmacodynamic models. The performances of different maintenance regimens were evaluated using simulation. Infusions every 3, 2 and one months were predicted to maintain 41%, 45% and 50% of patients with CI <4 L/min/m(2) at 24 months, respectively. The fraction of patients with <20 min epistaxis per month was predicted to be 34%, 43% and 60%, with infusion every 3, 2 or one months, respectively. Simulations of the effects of different maintenance dosing regimens predict that monthly 5 mg/kg infusions of bevacizumab should allow sustained control of both cardiac index and epistaxis.