Treatment of anaplastic thyroid carcinoma in vitro with a mutant vaccinia virus.

Abstract

Anaplastic thyroid carcinoma (ATC) is a fatal disease resistant to all conventional treatments. Novel therapies are needed to improve dismal outcomes. A replication-competent vaccinia virus (GLV-1h68) was engineered by inserting expression cassettes encoding Renilla luciferase-green fluorescent protein (GFP), beta-galactosidase, and beta-glucuronidase into the genome of LIVP strain. Infection of 6 ATC cell lines by GLV-1h68 was detected in vitro at 12, 24, and 36 hours. Viral proliferation was measured through viral plaque assays. Cytotoxicity was measured daily at a multiplicity of infection (MOI) of 0.01, 0.1 and 1. Viral infection was detected in all cell lines by 24 hours and increased in intensity at 36 hours. Logarithmic viral replication was detected in all cell lines. At MOI 1, <13% cell survival was measured in 5 cell lines by day 7. At MOI 0.01, 3 cell lines showed <21% cell survival by day 7. Luciferase and beta-galactosidase activity at 24 hours correlated with cytotoxicity at MOI 0.01 on day 5. A replication-competent vaccinia virus has significant infectious and oncolytic activity against a panel of human ATC. These results encourage future in vivo and clinical studies for this novel agent to treat this fatal cancer.