Complex sentence: She worked for two years for Millennium Pharmaceutical Corporation, a biopharmaceutical company focused on oncology and inflammation; after leaving them, she worked for Darwin Molecular Corporation starting in for two years.
Split into simpler sentences: She worked for two years for Millennium Pharmaceutical Corporation, a biopharmaceutical company focused on oncology and inflammation. After leaving Millennium Pharmaceutical, she worked for Darwin Molecular Corporation starting in for two years.