Pharmacokinetics/pharmacodynamics by Race: Analysis of a Peginterferon Β-1A Phase 1 Study.

Background: Black/African American participants are underrepre-sented in clinical trials for multiple sclerosis but can experience a greater burden of disease than other racial groups in the United States. A phase 1, open-label, crossover study that demonstrated bioequiva-lence of subcutaneous and intramuscular injection of peginterferon 8-1a in healthy volunteers enrolled similar proportions of Black and White participants, enabling a post hoc subgroup analysis comparing these groups.Methods: Peginterferon 8-1a (125 mu g) was administered by subcutane-ous or intramuscular injection, followed by a washout period before a second injection using the alternative method. The primary pharmaco-kinetic and pharmacodynamic endpoints were maximum observed con-centration (Cmax) and area under the concentration-time curve from hour 0 to infinity (AUCinf) of study drug and serum concentration of neop-terin, respectively. Safety and tolerability were included as sec-ondary endpoints.Findings: This analysis included 70 (5 1.5%) Black and 59 (43.3%) White participants. Peginterferon 8-1a Cmax was 29.8% higher in Black than in White participants following subcutaneous administration but was similar following intramuscular administration. Mean AUCinf was 31.0% and 11.8% greater in Black than in White participants with subcu-taneous and intramuscular administration, respectively. Pharmacody-namics and safety signals were similar between groups, although Black participants reported numerically fewer adverse events.Conclusions: No clinically meaningful differences were identified be-tween Black and White participants related to peginterferon 8-1a administration, supporting the approved dose of 125 mu g/mL peginter-feron 8-1a. Future clinical studies should include sufficiently diverse populations to ensure accurate assessments of treatment response.