6,7-Dimethoxy-2-methyl-N-[(1R)-1-[4-[2-[(methylamino)methyl]phenyl]-2-thienyl]ethyl]-4-quinazolinamine is an effective and selective inhibitor of SOS1, blocking RAS activation via disruption of the KRAS-SOS1 interaction without significantly targeting the EGFR receptor. Thus, it has potential use in treatment of hyperproliferative disorders.