Safety of Single Doses of CSL889 in Adult Patients With Sickle Cell Disease

Inclusion Criteria: * Diagnosis of SCD as documented in the subject's medical record * Aged 18 to 60 years, inclusive * Stable SCD for at least 30 days before Day 1. Stable SCD is defined as the subject being at his or her medical baseline, with no evidence of worsening of disease over the last 30 days (including VOC, recent major surgery, hospitalization, serious infection, significant bleeding, cerebrovascular accident, seizures, or IV opioids)(Part A) * Uncomplicated VOC requiring parenteral opioid treatment and admission to hospital for management. Uncomplicated VOC is defined as sickle cell pain without the following associated clinical features (Part B): * Fever (\> 38.5 °C) * Hypotension (\< 90/60 mmHg) * Hypoxia (\< 90% oxygen saturation on room air, or requiring oxygen therapy to maintain oxygen saturation above 90%) * New neurological signs and / or symptoms clinically suggestive of stroke or transient ischemic attack * Signs and / or symptoms of Acute Chest Syndrome, accompanied by any new pulmonary infiltrate on chest radiography (chest X-ray to be performed if clinically indicated and according to local clinical guidelines) * Subject is either not taking one of the study permitted SCD therapies (hydroxyurea, L-glutamine, L-glutaminecrizanlizumab, and/or voxelotor) or subject has been taking one or more of those for at least 30 days before Day 1 and is on a stable, well tolerated regimen that is planned to continue without change throughout the study Exclusion Criteria: * History of primary hemorrhagic stroke * History or evidence of inherited bleeding diathesis or significant coagulopathy at risk for bleeding * Weight \>110 kg (242 lbs) * Surgery within 30 days before Day 1 or any preplanned surgeries during the study (minor surgeries may be permitted under local anesthesia before screening, with permission of the medical monitor) * Female subjects who are pregnant or breastfeeding * Female subject of childbearing potential or fertile male subject either not using or not willing to use an acceptable method of contraception to avoid pregnancy during the study and for 30 days after receipt of CSL889. * Treatment with any other drug / biologic that is newly approved for SCD during the conduct of this study within 90 days before Day 1. Exceptions: crizanlizumab \[Adakveo®\] and voxelotor \[Oxbryta®\] \] are permitted (where prescribed). * Treatment with another investigational product within 30 days or within 5 half-lives of the product (whichever is greater) before Day 1 * Vaccination within 30 days before Day 1, or planned vaccination during the study * Body-mass index \< 16 kg/m2 or weight \< 50 kg (110 lbs) * History of anaphylactic-type reactions, transfusion related reaction, asthma, or autoimmune disease