The ELLIPSE Study: A Phase-1 Study Evaluating the Tolerance of Bevacizumab Nasal Spray to Treat Epistaxis in Hereditary Hemorrhagic Telangiectasia

Inclusion Criteria: * Age ≥ 18 years. * Patients who give voluntary, informed consent and sign a consent form. * Patients affiliated with the French universal health care system. * Patients treated for HHT, that has been confirmed clinically (presence of at lease 3 Curaçao criteria) and/or by molecular biology. * Patients who fill out epistaxis tally sheets completely in the three months before inclusion. * Patients who present severe epistaxis averaging over 30 minutes in the three months before inclusion ((duration M1 + duration M2 + duration M3) / 3). * Patients whose number of red blood cell transfusions in the six months before inclusion is known. * Patients who have not undergone nasal surgery in the three months before inclusion. Exclusion Criteria: * Pregnant women or women who could become pregnant during the study. * Patients not affiliated with the French universal health care system. * Patients who are protected adults according to the terms of the law (French public health laws). * Refusal to give consent. * Patients whose HHT diagnosis has not be confirmed clinically and/or by molecular biology. * Infectious episode. * Patients presenting unchecked hypertension at the time of inclusion (systolic BP \> 150 mmHg and/or diastolic BP \> 100 mmHg) with or without treatment. -Patients with hypertension can be included, once blood pressure levels have been controlled by appropriate medical treatment. * Participation in another therapeutic trial in the 28 days before inclusion. Patients who have already being treated with bevacizumab by intravenous infusion. * A known hypersensitivity to the active substance or one of its excipients.A known hypersensitivity to products containing Chinese hamster ovarian (CHO) cells or to other human or humanized recombinant antibodies.