Additional Study Information: The purpose of this study is to find out more about how the study drug called talimogene laherparepvec will be used in children/adolescents/young adults with advanced solid tumors not involving the central nervous system that are available for direct injection. This is a phase 1 study, multicenter, open-label study, that means all subject enrolled in the study will be assigned talimogene laherparepvec. The study drug is a genetically modified virus. The virus' genes were modified in a laboratory to make the virus active in the tumor cell but not in normal cell. Talimogene laherparepvec is given as a direct injection into the tumors with a needle. Male or female subjects aged 2 to 21 years will be enrolled into 2 cohorts stratified by age.