Our current findings that reovirus is preferentially active in KRAS mutant CRC, and its observed synergy with irinotecan, has prompted the initiation of a phase I trial testing the reovirus with FOLFIRI (folinic acid, 5-FU, and irinotecan; a standard second line option for patients with metastatic CRC) [28] in KRAS mutant mCRC, and preliminary results have been encouraging, with median progression free survival (PFS) of 7.4 months [29]. Here, KRAS is linked to colorectal carcinoma.