Difelikefalin in Black/African American Hemodialysis Patients with Moderate-to-Severe Pruritus: Post hoc Analysis of KALM-1 and KALM-2

Abstract

Introduction: Black and African American (AA) people are over-represented in the kidney failure population; therefore, the safety and efficacy of difelikefalin in Black/AA patientswas evaluated. Methods: This was a post hoc, pooled exploratory subgroup analysis of the Phase 3 KALM-1 and -2 studies. Patients undergoing hemodialysis (HD) who had moderateto- severe chronic kidney disease-associated pruritus (CKD-aP) at enrollment were stratified into self-reported Black/AA or White subgroups. Patients were randomized (1:1) to receive intravenous (IV) difelikefalin 0.5 ?g/kg or placebo for 12 weeks. Difelikefalin efficacy was assessed with validated patient-reported outcome questionnaires: 24-h Worst Itch Numerical Rating Scale (WI-NRS), 5-D itch, and Skindex?10. Results: There were 249 (29.3%) patients from the KALM studies that self-identified as Black/AA (n = 135 difelikefalin; n = 114 placebo). Clinicallymeaningful (?3-point) reduction in WI-NRS score was achieved by 47.9% of Black/AA patients with difelikefalin versus 24.6% with placebo (p > 0.001). More Black/AA patients achieved a ?5-point 5-D itch total improvement (54.9% vs. 35.7%; p = 0.013) and a ?15-point Skindex-10 score improvement with difelikefalin versus placebo (49.0% vs. 28.9%; p = 0.006) compared with White patients. Incidence of treatment-emergent adverse events (TEAEs) was higher for Black/AA patients (difelikefalin: 78.5%; placebo: 70.8%) versus White patients (difelikefalin: 64.8%; placebo: 61.8%). Conclusion: In this post hoc analysis, difelikefalin was efficacious in the Black/AA population and had an acceptable safety profile.