Summary

This is a phase 2, randomized, multiple-dose, placebo-controlled study designed to evaluate the safety, efficacy, and pharmacokinetics (PK) of CSL889 (human hemopexin) when given intravenously (IV) to adults and adolescents with sickle cell disease (SCD) experiencing vaso-occlusive crises (VOC). The main objectives of the study are to evaluate the safety and tolerability of CSL889 in study participants, and to assess how CSL889 affects the time it takes for VOC to resolve in participants with SCD.

Age: 12 Years and older

Gender: All

Start Date: 08/07/2025

Primary Completion Date (Estimated): 10/22/2027

Study Completion Date (Estimated): 10/22/2027

Accepts Healthy Volunteers: No

Trial Purpose and Description

Eligibility Criteria

Age: 12 Years and older

Gender: All

Accepts Healthy Volunteers: No

Inclusion criteria:

* At the time of informed consent:

* 18 years of age (adults); or

* 12 to less than (\<) 18 years of age (adolescents, where approved and when enrollment for adolescents has been opened by the sponsor, with the endorsement of the Independent Data Monitoring Committee \[IDMC\])

* Diagnosed with SCD (any genotype).

* Presented at the study site with a new acute VOC necessitating treatment with parenteral opioids.

Exclusion criteria:

* VOC pain onset greater than (\>) 72 hours before administration of first parenteral opioid.

* Must not have a history of \> 5 VOCs requiring hospital admission in the past 6 months; or signs and / or symptoms of ACS; or new neurological symptoms suggestive of acute stroke or transient ischemic attack; or any stage (acute kidney injury) AKI; or been discharged from inpatient hospital admission for VOC or other vaso-occlusive event within 14 days before the current presentation.

* Serum hemoglobin \< 6 g/dL, serum ferritin ≥ 2000 ng/mL, receiving an approved medication for SCD that has not been on a stable, well-tolerated regimen, currently taking methadone or buprenorphine.