Based on promising preclinical data with sequential selleck products treatment, clinical proof-of-concept was explored in HCC patients who had completed JX-594 treatment as a single agent on a phase 2 trial. After progression following JX-594, standard sorafenib therapy was evaluated in these patients. In order to assess whether the findings in JX-594 treated patients were typically seen with sorafenib alone, the effect of sorafenib alone was assessed in concurrent and recent historical controls at the same institutions. Finally, a renal cell carcinoma patient was treated with JX-594 followed by sunitinib (Sutent, Pfizer, New York, NY), another small molecule inhibitor of VEGFR with an activity profile similar to sorafenib. Renal cell cancer (RCC) is similar to HCC in that it is a highly vascularized tumor type, and sunitinib shares similar VEGFR inhibition with sorafenib.

Therefore, this RCC patient shares similar histologic and treatment features to the three HCC patients. Results Sorafenib inhibits JX-594 replication in vitro Based upon our earlier clinical studies9 we predicted that JX-594 would be able to infect and kill a wide variety of cell lines derived from human HCC. Indeed we found that JX-594, in vitro, infects and destroys several different human HCC cell lines. HepG2, SNU423, SNU475, SNU449, and PLC/PRF/5 have been tested and shown to be susceptible to JX-594 infection by burst and/or plaque assay (Figure 1a�Ce). In addition, the ability of a sorafenib resistant/adapted derivative of PLC/PRF/5 to support JX-594 replication was evaluated.

To generate sorafenib resistant/adapted cultures, PLC/PRF-5 cells were grown in vitro at increasing doses of sorafenib for a total of 3 months, starting at a sorafenib concentration of 1 ��mol/l and increasing up to 6 ��mol/l. The resistant/adapted cells supported JX-594 replication at a Brefeldin_A level comparable to its parental sorafenib sensitive clone (Figure 1a). As discussed earlier, the replication of JX-594 is determined in part by activation of the EGFR/Ras/Raf pathway and so we reasoned that as a Raf kinase inhibitor, sorafenib might theoretically affect virus replication. We therefore tested the ability of JX-594 to infect and replicate tumor cells in the presence of sorafenib. JX-594 was allowed to infect monolayers of A2780 (ovarian cancer cell line) or HepG2 (HCC cell line) in the absence or presence of increasing concentrations of sorafenib, and JX-594 replication was assessed by measuring plaque formation on the original monolayer, and the production of new plaque-forming units (pfu, replicative burst) (Figure 1b,c). JX-594 plaque formation and replication were inhibited in a dose-related fashion (Figure 1b,c); inhibition was >95% at 4 ��mol/l sorafenib.