5612539 TRIAL IN PROGRESS: THE RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED PHASE 2A CROSSWALK-C TRIAL EVALUATING THE EFFICACY OF CROVALIMAB AS ADJUNCT TREATMENT IN THE PREVENTION OF 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, with either homozygous inheritance or heterozygous co-inheritance with other pathogenic variants of the β-globin gene. Hemoglobin S, produced as a result of this point mutation, polymerizes within RBCs under certain conditions, distorting them and generating dense and sickle RBCs. These pathologic RBCs contribute to microvascular occlusions, which may present as acute painful episodes called VOEs. Pts with SCD may also have severe chronic anemia, chronic pain, immune dysfunction, and progressive multi-organ damage. Current therapies for SCD include hydroxyurea, as well as newer treatments such as L-glutamine, crizanlizumab, and voxelotor. Despite these treatments, considerable morbidity and mortality among pts with SCD represents a significant unmet medical need. Complement pathway activation has been reported in pts with SCD at baseline, in acute pain crises, and in delayed hemolytic transfusion reaction. Accumulating nonclinical data suggest the potential multimodal role for complement dysregulation in the pathophysiology of SCD, including vaso-occlusion, hemolysis, inflammation, thrombogenicity, endothelial activation, and end-organ damage.1 The complement pathway can be targeted with crovalimab, a novel anti-C5 monoclonal antibody that allows for small-volume subcutaneous (SC) self-injection. 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.2 Aim: CROSSWALK-c (NCT05075824) is a randomized, double-blind, placebo-controlled, Phase 2a study evaluating the efficacy and safety of crovalimab as adjunct therapy in preventing VOEs in pts with SCD. Methods: Pts aged 12 to 55 years, weighing ≥40 kg, with a confirmed diagnosis of SCD, homozygous hemoglobin S (HbSS) or sickle cell β0 thalassemia (HbSβ0), and presenting with 2 to 10 VOEs are eligible, including pts on concurrent SCD-directed therapies. Vaccinations against Neisseria meningitidis, Haemophilus influenzae type B, and Streptococcus pneumoniae are required. Pts with a history of hematopoietic stem cell transplant will be excluded. Eligible pts will be randomized 1:1 to the crovalimab or placebo arms (Figure). An initial intravenous loading dose of crovalimab or placebo will be given on Week 1, Day 1, followed by SC dose on Week 1, Day 2, and then weekly SC doses on Weeks 2–4. Starting Week 5, a maintenance dose will be given every 4 weeks for 48 weeks. All study treatment will be given according to a weight-based tiered dosing schedule (pts weighing ≥ 40 kg to < 100 kg and pts ≥ 100 kg). The primary objective is to evaluate the efficacy of crovalimab vs placebo based on the annualized rate of medical facility VOEs. Key secondary efficacy objectives are the annualized rate of acute chest syndrome, the annualized rate of home VOE, and change in urinary albumin–creatinine ratio, tricuspid regurgitant jet velocity, and Patient-Reported Outcomes Measurement Information System (PROMIS)-Fatigue score in adults, from baseline to Week 49. Safety, pharmacokinetic, immunogenicity, and exploratory biomarker objectives will also be evaluated. Protocol updates are in progress. Results: Primary results are expected in July 2024. Summary: CROSSWALK-c is enrolling pts with SCD and chronic VOEs in six countries.