Children's Hospital of Philadelphia

The provided news articles do not directly mention Children's Hospital of Philadelphia (CHOP). Therefore, it's impossible to provide a summary about CHOP based solely on this information. The articles discuss topics such as FDA proposals for customized drugs and therapies for rare diseases, and the cancellation of a US-funded hepatitis B vaccine study in Guinea-Bissau. While CHOP is a leading pediatric hospital often involved in research and treatment of rare diseases and vaccine studies, its direct involvement in these specific events cannot be confirmed or elaborated upon based on the given context. Without explicit mention, any connection to CHOP would be speculative.