As previously reported, Guggenheim analyst Michael Schmidt downgraded Mirati Therapeutics (MRTX) to Neutral from Buy, noting that the shares have nearly tripled since data were presented at the European Society for Medical Oncology, or ESMO, meeting in October. While Schmidt said Amgen's (AMGN) KRAS inhibitor Phase I data presented at the American Society of Clinical Oncology meeting validates MRTX849's potential mechanism of action, he sees a "lot of upside" priced in at the current valuation despite the remaining development risks. He also believes investor expectations have significantly increased ahead of Mirati's own Phase I data presentation in the second half of the year.