By Christy Santhosh and Shashwat Chauhan Aug 19 (Reuters) - Moderna shares more than doubled on Wednesday, adding about $30 billion to its market value, after promising late-stage data on its personalized mRNA cancer ‌therapy developed with Merck sent investors piling into the stock. The therapy is central to Moderna's ‌efforts to prove that its mRNA technology can succeed beyond its COVID-19 vaccine franchise and infectious disease shots, as it seeks to ​build a more durable revenue base. The company ...