P119: TRIAL IN PROGRESS: THE RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED PHASE 1B CROSSWALK-A TRIAL EVALUATING THE SAFETY OF CROVALIMAB FOR THE MANAGEMENT OF ACUTE UNCOMPLICATED VASO-OCCLUSIVE EPISODES (VOES) IN PATIENTS (PTS) WITH SICKLE CELL DISEASE (SCD)

Abstract

Background: SCD is a group of autosomal recessive red blood cell (RBC) disorders caused by a single point mutation in the β-globin gene, resulting in the production of hemoglobin S (HbS). HbS polymerizes within RBCs under certain conditions, leading to the distortion of the RBC membrane and generation of dense and sickle RBCs. These pathologic RBCs contribute to microvascular occlusions, which may present as acute, painful episodes called VOEs. Although most VOEs are managed at home, >70% of emergency department visits and >90% of hospitalizations for SCD are VOE-related.1,2 Additionally, acute chest syndrome is one of the most severe complications of VOEs and is a leading cause of mortality.3,4 As there are no targeted therapies for the management of VOEs, treatment is currently limited to pain management, blood exchange transfusion (with the risk of complications), and other supportive care, which represents a significant unmet medical need. Overall, accumulating nonclinical data suggest a multimodal role for complement dysregulation in the pathophysiology of SCD including vaso-occlusion, hemolysis, inflammation, thrombogenicity, endothelial activation, and end-organ damage.5 Complement pathway activation has been described in pts with SCD at baseline, in acute pain crises, and in pts with delayed hemolytic transfusion reaction. The complement pathway can be targeted with crovalimab, which is a novel, engineered, anti-complement C5 monoclonal antibody. In a Phase 1/2 paroxysmal nocturnal hemoglobinuria (a complement-mediated disorder) study, crovalimab showed rapid and sustained complement inhibition with promising efficacy and safety.6 Aims: CROSSWALK-a (NCT04912869) is a randomized, double-blind, placebo-controlled, Phase 1b study evaluating the safety of crovalimab in managing acute uncomplicated VOEs in pts with SCD. Methods: Pts aged 12 to 55 years, weighing ≥40 kg, and with a confirmed diagnosis of SCD homozygous hemoglobin S (HbSS) or sickle cell β0 thalassemia (HbSβ0) will be enrolled (Figure). Pts must present with an acute uncomplicated VOE, requiring hospitalization and treatment with parenteral opioid analgesics. Vaccinations against Neisseria meningitidis, Hemophilus influenzae type B, and Streptococcus pneumoniae must be current. Eligible pts will be randomized 2:1 to receive either a single intravenous weight-based tiered dose of crovalimab or placebo. All pts will continue with pain management and other supportive care for their VOE, and may continue concurrent SCD-directed therapies. Pts will be followed during hospitalization until discharge and will also be followed post-discharge during an observational period. The maximum total study duration for an individual pt, including the hospitalization and observational periods, will be 12 weeks. The primary objective is to evaluate the incidence and severity of adverse events according to National Cancer Institute Common Terminology Criteria for Adverse Events, Version 5.0, incidence and severity of infusion-related reactions and hypersensitivity, and change from baseline in targeted vital signs and clinical laboratory test results. Efficacy, pharmacokinetics, pharmacodynamics, immunogenicity, and exploratory biomarker endpoints will also be evaluated. Results: CROSSWALK-a is scheduled to be completed in September 2023. Summary: CROSSWALK-a is enrolling pts with SCD in 5 countries.