AS2553627 is a novel JAK inhibitor. AS2553627 prevents chronic rejection in rat cardiac allografts. AS2553627 potently inhibited JAK kinases but showed no inhibition of other kinases, including TCR-associated molecules. In a rat cardiac transplant model, oral administration of AS2553627 alone or co-administration with a sub-therapeutic dose of tacrolimus effectively prolonged cardiac allograft survival, suggesting the efficacy in treating acute rejection. AS2553627 may be a therapeutic candidate for the prevention of not only acute but also chronic rejection in cardiac transplantation.
