This clinical study is a multicenter open-label study on the adult and pediatric hematopoietic stem cell transplantation (HSCT) patients. The primary objective is to confirm the preventive efficacy for herpes simplex virus (HSV) infection of 256U87 (VACV: valaciclovir) due to the treatment before or immediately after hematopoietic stem cell transplantation. The secondary objective is to confirm the safety of VACV in the case of its use for such a purpose.~This clinical study consists of the following two periods: the screening period lasting 7 days at the longest and the administration period from 7 days before HSCT to 35 days after HSCT (43 days in total). During the administration period, adult patients are orally given a VACV tablet twice daily, while pediatric patients are orally given VACV granules twice daily at a dose of 25 mg/kg b.w. (maximum dose per treatment: 500 mg). Pediatric patients weighing 40 kg or over may be orally given a VACV tablet twice daily.
The purpose of this study is to evaluate the preventive efficacy for HSV infection and safety of valaciclovir (VACV) in the adult and pediatric HSCT patients.