Michael Tardugno, chief executive of tiny Celsion Corp, is convinced he has a $1 billion cancer therapy on his hands with its ThermoDox treatment for liver cancer. The company, with a market valuation of only about $70 million and all of 16 employees, is not trying to reinvent the wheel. But by placing a very old cancer drug - the chemotherapy doxorubicin - into a new delivery method and adding heat, Celsion believes it has a recipe for success that can address a large need in cancer. “Certainly this is a $1 billion drug,” Tardugno told Reuters in an interview.