Abstract
<b>Background:</b> Bevacizumab—a humanized monoclonal antibody—has been widely used to treat patients with hereditary hemorrhagic telangiectasia (HHT), but no randomized trial has yet been conducted.<br /><b>Methods:</b> This study is a double‐blind multicenter randomized phase 2 trial with a 1:1 active‐treatment‐to‐placebo ratio. We included patients over the age of 18 with a confirmed diagnosis and the need for at least four red blood cell (RBC) units transfused in the 3 months before study enrollment. Bevacizumab was administered at a dose of 5 mg/kg every 14 days with a total of six injections. The primary efficacy criterion was a decrease of at least 50% in the cumulative number of RBC units transfused in a 3‐month period before and after treatment.<br /><b>Results:</b> A total of 24 patients (12 in each group) were included and randomized at 4 different centers. In intention‐to‐treat analysis, 63.6% of patients (7/11) in the bevacizumab group versus 33.3% of patients (4/12) in the placebo group decreased the number of blood transfusions by at least 50% (p = 0.22). Hemoglobin levels significantly improved at 6 months in the bevacizumab versus placebo group (p = 0.02). The pharmacokinetics study revealed that patients with high exposure to bevacizumab had a significant decrease in RBC transfusions (p = 0.03). Fifty‐nine adverse events were observed, 34 in the placebo arm versus 25 in the bevacizumab arm.<br /><b>Conclusion:</b> Though the present trial was underpowered, patients with HHT receiving bevacizumab required numerically fewer red blood cell transfusions than those receiving placebo, particularly those with high exposure.