A Study to Evaluate the Safety and Efficacy of a Modigraf® Based Immunosuppression Regimen in De Novo Pediatric Allograft Liver and Kidney Transplantation Recipients

Inclusion Criteria: * Participant's parent(s) or their legal representative(s), and participant where applicable agrees not to participate in another interventional study while participating in the present study from 1 month before screening to the end of the study. Exclusion Criteria: * Participant has previously received another organ transplant. * Participant has a high immunological risk, defined as a panel reactive antibody (PRA) score \> 50% in the previous 6 months (only applicable for kidney transplantation recipients). * Cold ischemia time of the donor kidney longer than 30 hours (only applicable for kidney transplantation recipients). * Bilateral kidney transplantation recipients (only applicable for kidney transplantation recipients). * Participant receives an ABO incompatible donor organ. * Participant has significant kidney impairment, defined as having serum creatinine ≥ 230 μmol/L (≥ 2.6 mg/dL) prior to transplantation (not applicable for kidney transplantation recipients). * Participant has significant liver disease, defined as having elevated alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST) and/or total bilirubin (TBL) levels 3 times the upper value of the normal range prior to transplantation (not applicable for liver transplantation recipients). * Participants with malignancies or a history of malignancy within the last 5 years. * Participant has a significant, uncontrolled systemic infection and/or severe diarrhea, vomiting, active upper gastrointestinal disorder that may affect the absorption of tacrolimus or has an active peptic ulcer. * Recipient or donor known to be human immunodeficiency virus (HIV), hepatitis C virus (HCV), or hepatitis B virus (HBV) positive. * Participant requires systemic immunosuppressive medication for any indication other than transplantation. * Participants taking or requiring to be treated with medication or substances prohibited by this protocol. * Known allergy or intolerance to steroids, macrolide antibiotics, basiliximab, or tacrolimus. * Participants with severe primary disease/complications/poor general condition which may be unsuitable for participating in this study. * Participant is currently participating in another clinical trial and/or has been taking any other study drug within 1 month prior to screening. * Participant is unlikely to comply with the visits scheduled in the protocol.