Alexion Pharmaceuticals will soon carry out a study to evaluate the safety, efficacy, pharmacokinetics, and pharmacodynamics of ALXN1820 in patients with sickle cell disease (SCD). The phase 2a study will evaluate multiple subcutaneous dosing levels in up to 30 adult participants.

The study is expected to start on December 1, 2022, and the primary completion date is February 15, 2024.

Sickle cell disease is a rare genetic condition that affects the production of hemoglobin, leading to the sickling of red blood cells and their premature breakdown. The disease causes anemia and painful vaso-occlusive crises (VOCs), in which the sickled blood cells get stuck in small blood vessels.

Read more about SCD therapies

ALXN1820 is an investigational bispecific antiproperdin minibody. There will be 3 experimental arms of the study, in which patients will receive (1) 300 milligrams (mg) once weekly, (2) 600 mg once every 4 weeks, or (3) 300 mg once every 2 weeks. All doses will be administered subcutaneously.

The primary outcome measure will be the number of trial participants with treatment-emergent severe and serious adverse events. Eight secondary outcome measures include pharmacokinetics as measured by serum ALXN1820 concentration and various changes from baseline in complement activity and concentrations of properdin, complement biomarkers, hemoglobin, hemolysis markers, hemopexin, and antidrug antibodies.

Eligible patients will be 18 to 65 years of age with a confirmed diagnosis of SCD in either HbSS or HbSβ0-thalassemia forms, a body weight of at least 40 kg, hemoglobin between 5.5 and 10 g/dL, and 1 to 10 VOCs in the past 12 months.

Exclusion criteria include hydroxyurea treatment initiation, termination, or changes during the study period, treatment with voxelotor or crizanlizumab within 60 days of enrollment, treatment with complement inhibitors, and receipt of chronic transfusions, among others.


Safety, efficacy, pharmacokinetic, and pharmacodynamic study of alxn1820 in adult participants with sickle cell disease. October 4, 2022. Accessed October 28, 2022.