Pharmacokinetics/pharmacodynamics by race: Analysis of a peginterferon β-1a phase 1 study

Black/African American participants are underrepresented 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 bioequivalence of subcutaneous and intramuscular injection of peginterferon β-1a in healthy volunteers enrolled similar proportions of Black and White participants, enabling a post hoc subgroup analysis comparing these groups.

Peginterferon β-1a (125 μg) was administered by subcutaneous or intramuscular injection, followed by a washout period before a second injection using the alternative method. The primary pharmacokinetic and pharmacodynamic endpoints were maximum observed concentration (C_max) and area under the concentration-time curve from hour 0 to infinity (AUC_inf) of study drug and serum concentration of neop-terin, respectively. Safety and tolerability were included as secondary endpoints.

This analysis included 70 (51.5%) Black and 59 (43.3%) White participants. Peginterferon β-1a C_max was 29.8% higher in Black than in White participants following subcutaneous administration but was similar following intramuscular administration. Mean AUC_inf was 31.0% and 11.8% greater in Black than in White participants with subcutaneous and intramuscular administration, respectively. Pharmacodynamics and safety signals were similar between groups, although Black participants reported numerically fewer adverse events.

No clinically meaningful differences were identified between Black and White participants related to peginterferon β-1a administration, supporting the approved dose of 125 μg/mL peginterferon β-1a. Future clinical studies should include sufficiently diverse populations to ensure accurate assessments of treatment response.

Funding for medical writing support was provided by Biogen (Cambridge, MA, USA).