These innovative biotechs could have plenty of upside ahead.In the volatile biotech industry, companies can see their shares soar over relatively short periods on strong clinical progress for exciting pipeline candidates.That's precisely what could happen to Exelixis (EXEL 2.18%) and Summit Therapeutics (SMMT 5.97%) this year. And the even better news is that there are reasons to consider holding onto these drugmakers' shares even beyond the next 12 months. Let's find out more. 1. ExelixisExelixis is a rela ...