Ethnic Bridging of Votoplam, a HTT Gene Splicing Modifier, Using Pharmacokinetic Comparison Between Caucasian and Japanese Subjects.

Votoplam is a novel, orally bioavailable, small molecule HTT gene splicing modifier that is being developed for the treatment of Huntington's disease. A single-dose, open-label, three-dose level (5, 10, 20 mg), parallel group ethnicity study was conducted to evaluate the pharmacokinetics and safety of votoplam in healthy Caucasian versus Japanese participants. Six participants per ethnic group were enrolled at each dose (12 participants per dose level overall). Thirty-five participants (N = 18 Japanese; N = 17 Caucasian) completed the study. Study results showed slightly higher exposure for Japanese participants at all dose levels. AUC0-last increased by 1.27-, 1.17-, and 1.29-fold, and Cmax increased by 1.58-, 1.19-, and 1.61-fold for 5, 10, and 20 mg, respectively, for Japanese compared with Caucasian participants. Doses proportionality was observed for both ethnicities. Few mild and moderate TEAEs were reported and were comparable between Japanese and Caucasian participants. In summary, votoplam pharmacokinetics and safety profiles are similar between healthy Japanese and Caucasian participants when administered in the single dose range of 5, 10, and 20 mg. Therefore, it is expected that dose adjustments should not be necessary in future clinical studies enrolling Japanese participants.