Repurpose of Ritlecitinib Reduces Neointima Formation and Enhances Endothelial Recovery Following Vascular Injury

Neointimal hyperplasia after vascular injury reflects excess smooth muscle cell (SMC) proliferation with impaired endothelial recovery. We tested the hypothesis that selective Janus kinase 3 (JAK3) inhibition with the FDA-approved drug Ritlecitinib limits neointima while accelerating reendothelialization.

We used mouse carotid wire injury and a human internal mammary artery (IMA) xenograft model to evaluate effects of genetic JAK3 loss in SMCs or oral Ritlecitinib in vascular remodeling. Mechanistic studies in SMCs assessed JNK/c-Jun signaling and its regulation of thrombospondin-1 (TSP-1) and vascular endothelial growth factor A (VEGF-A) using RNA-seq and CUT&RUN. Rescue experiments tested whether VEGF-A neutralization or exogenous TSP-1 reversed the antineointimal effects. Patient-derived IMA SMCs were analyzed for variabilities in drug responses.

Genetic JAK3 loss in SMCs or oral Ritlecitinib reduced neointimal area and intima/media ratio and increased luminal CD31+ coverage in both models. In SMCs, Ritlecitinib suppressed JNK/c-Jun signaling, downregulated TSP-1, and restored VEGF-A, shifting the milieu toward endothelial regeneration. RNA-seq and CUT&RUN corroborated JNK/c-Jun- dependent control of TSP-1 and VEGFA. VEGF-A neutralization or exogenous TSP-1 abrogated the anti-neointimal phenotype. In patient-derived IMA SMCs, variable drug response was linked to the JAK3 Pro893Asn variant and a VEGFA promoter SNP.

Selective JAK3 inhibition by Ritlecitinib simultaneously restrains SMC proliferation and promotes endothelial repair through modulating TSP-1 and VEGF-A activities. Ritlecitinib merits clinical evaluation as a precision therapy to prevent restenosis, with genetic stratification to identify responders.