Safety & Efficacy of NV1020 in Colorectal Cancer Metastatic to the Liver

This study is an open-label study. It has two stages. Stage 1 is a dose escalation phase of the study to determine and evaluate the safety and tolerability of repeated treatments with a genetically engineered herpes simplex virus NV1020 administered locoregionally to the liver. Stage 2 is to evaluate the dose found in Stage 1 to be "optimally tolerated". Stage 2 is to assess the efficacy of the optimally tolerated dose of NV1020 by itself and in combination with second-line chemotherapy. Assignment to Stage 1 or Stage 2 of the study is determined by when the patient enters the study.