Roche Holding AG’s breast cancer medicine Perjeta succeeded in the drugmaker’s most hotly anticipated patient study, bolstering a franchise that could exceed $9 billion in sales by 2021. Patients who took Perjeta alongside chemotherapy and Roche’s own Herceptin drug after surgery for early breast cancer had a reduced risk of dying or seeing their breast tumors return than those on the older treatments alone, the Swiss drugmaker said in a statement Thursday.