Effective Oncolytic Vaccinia Therapy for Human Sarcomas

Background Approximately one fourth of bone and soft-tissue sarcomas recur after prior treatment. GLV-1h68 is a recombinant, replication-competent vaccinia virus that has been shown to have oncolytic effects against many human cancer types. We sought to determine whether GLV-1h68 could selectively target and lyse a panel of human bone and soft-tissue sarcoma cell lines in vitro and in vivo . Methods GLV-1h68 was tested in a panel of four cell lines including: fibrosarcoma HT-1080, osteosarcoma U-2OS, fibrohistiocytoma M-805, and rhabdomyosarcoma HTB-82. Gene expression, infectivity, viral proliferation, and cytotoxicity were characterized in vitro . HT-1080 xenograft flank tumors grown in vivo were injected intratumorally with a single dose of GLV-1h68. Results All four cell lines supported robust viral transgene expression in vitro . At a multiplicity of infection (MOI) of five, GLV-1h68 was cytotoxic to three cell lines, resulting in >80% cytotoxicity over 7 d. In vivo , a single injection of GLV-1h68 into HT-1080 xenografts exhibited localized intratumoral luciferase activity peaking at d 2–4, with gradual resolution over 8 d and no evidence of spread to normal tissues. Treated animals exhibited near-complete tumor regression over a 28-d period without observed toxicity. Conclusion GLV-1h68 has potent direct oncolytic effects against human sarcoma in vitro and in vivo . Recombinant vaccinia oncolytic virotherapy could provide a new platform for the treatment of patients with bone and soft tissue sarcomas. Future clinical trials investigating oncolytic vaccinia as a therapy for sarcomas are warranted.