H5.110CMVhIFN-β treatment does not inhibit the growth of a murine colorectal cell line in an intrahepatic microscopic disease athymic nude mouse liver metastases model; however, H5.110CMVmIFN-β, which expresses murine IFN-β, inhibits the growth of murine colorectal liver tumors and improves survival in a liver metastases model. (a) CT26 cells were directly injected in the livers of athymic nude mice. On day 5, mice were randomized to receive PBS, H5.010CMVβ-gal, or H5.110CMVhIFN-β via tail vein injection. On day 19, livers were harvested for tumor volume measurement. Each point represents a single animal, and mean tumor volume is indicated by the large cross. (b) CT26 cells were injected directly in the livers of BALB/c mice. On day 5, mice were randomized to receive PBS, H5.010CMVβ-gal, or H5.110CMVmIFN-β (AdmIFN-β) via tail vein injection. On day 19, livers were harvested for tumor volume measurement (P = 0.0001). (c) CT26 cells were injected into the spleens of BALB/c mice. On day 5, mice were randomized to receive PBS, H5.010CMVβ-gal, or H5.110CMVmIFN-β via tail vein injection, or daily intraperitoneal injections of 10,000 U of recombinant mIFN-β protein. Mice were sacrificed when they became moribund by preestablished criteria, and their survival curves were plotted. (d) CT26 cells were injected subcutaneously into the flanks of BALB/c mice. On day 5, mice were randomized to receive PBS, H5.010CMVβ-gal, or H5.110CMVmIFN-β via tail vein injection. Tumors were measured twice per week and tumor volumes were estimated assuming an ellipsoid shape (P < 0.05).