Camptotheca has been intensively studied in both the U.S. and China and yields the drug hydroxycamptothecin (used for acute myelocytic and lymphocytic leukemias), also not approved in the U.S. Strychnos, which contains strychnine, has anticancer properties but is not licensed for use here (it is an ingredient of the Chinese formula Ping Xiao Dan, used for many types of cancer).