RESUMO
Oncolytic viruses are generally designed to be cancer selective on the basis of a single genetic mutation. JX-594 is a thymidine kinase (TK) gene-inactivated oncolytic vaccinia virus expressing granulocyte-macrophage colony-stimulating factor (GM-CSF) and lac-Z transgenes that is designed to destroy cancer cells through replication-dependent cell lysis and stimulation of antitumoral immunity. JX-594 has demonstrated a favorable safety profile and reproducible tumor necrosis in a variety of solid cancer types in clinical trials. However, the mechanism(s) responsible for its cancer-selectivity have not yet been well described. We analyzed the replication of JX-594 in three model systems: primary normal and cancer cells, surgical explants, and murine tumor models. JX-594 replication, transgene expression, and cytopathic effects were highly cancer-selective, and broad spectrum activity was demonstrated. JX-594 cancer-selectivity was multi-mechanistic; replication was activated by epidermal growth factor receptor (EGFR)/Ras pathway signaling, cellular TK levels, and cancer cell resistance to type-I interferons (IFNs). These findings confirm a large therapeutic index for JX-594 that is driven by common genetic abnormalities in human solid tumors. This appears to be the first description of multiple selectivity mechanisms, both inherent and engineered, for an oncolytic virus. These findings have implications for oncolytic viruses in general, and suggest that their cancer targeting is a complex and multifactorial process.
Assuntos
Neoplasias/metabolismo , Vírus Oncolíticos/fisiologia , Poxviridae/fisiologia , Transdução de Sinais/fisiologia , Replicação Viral/fisiologia , Animais , Western Blotting , Linhagem Celular Tumoral , Receptores ErbB/genética , Receptores ErbB/metabolismo , Células HeLa , Humanos , Técnicas In Vitro , Leucócitos Mononucleares , Camundongos , Camundongos Nus , Neoplasias/genética , Terapia Viral Oncolítica , Vírus Oncolíticos/genética , Poxviridae/genética , Transdução de Sinais/genética , Replicação Viral/genéticaRESUMO
Ideally, an oncolytic virus will replicate preferentially in malignant cells, have the ability to treat disseminated metastases, and ultimately be cleared by the patient. Here we present evidence that the attenuated vesicular stomatitis strains, AV1 and AV2, embody all of these traits. We uncover the mechanism by which these mutants are selectively attenuated in interferon-responsive cells while remaining highly lytic in 80% of human tumor cell lines tested. AV1 and AV2 were tested in a xenograft model of human ovarian cancer and in an immune competent mouse model of metastatic colon cancer. While highly attenuated for growth in normal mice, both AV1 and AV2 effected complete and durable cures in the majority of treated animals when delivered systemically.
Assuntos
Imunidade Inata/fisiologia , Interferon beta/metabolismo , Vírus da Estomatite Vesicular Indiana/metabolismo , Transporte Ativo do Núcleo Celular , Animais , Neoplasias do Colo/terapia , Neoplasias do Colo/virologia , Feminino , Humanos , Imunidade Inata/imunologia , Interferon beta/imunologia , Neoplasias Pulmonares/terapia , Neoplasias Pulmonares/virologia , Camundongos , Camundongos Knockout , Modelos Biológicos , Mutação , Neoplasias Experimentais/virologia , Análise de Sequência com Séries de Oligonucleotídeos , Neoplasias Ovarianas/terapia , Neoplasias Ovarianas/virologia , Transdução de Sinais , Vírus da Estomatite Vesicular Indiana/genética , Proteínas da Matriz Viral/metabolismo , Replicação Viral/genética , Replicação Viral/fisiologiaRESUMO
PURPOSE: Nasopharyngeal carcinoma (NPC) is a malignancy of the head and neck region that is associated with EBV latency. Curative treatments for NPC achieve modest survival rates, underscoring a need to develop novel therapies. We evaluated the therapeutic potential of a mutant vesicular stomatitis virus (VSVDelta51) as single treatment modality or in combination with ionizing radiation (RT) in NPC. EXPERIMENTAL DESIGN: MTS assay was used to assess cell viability in vitro; apoptosis was measured using propidium iodide staining and caspase activation. In vivo experiments were conducted using tumor-bearing nude mice with or without local RT (4 Gy). Apoptosis was assessed in excised tumor sections with terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining. RESULTS: Our data showed that NPC cells are exquisitely sensitive to VSVDelta51 oncolysis, which correlated with the presence of EBV. Efficacy of VSVDelta51 against NPC cells was further augmented when combined with RT. A single systemic injection of VSVDelta51 achieved 50% survival in treated mice, which increased to 83% when combined with local tumor RT. In addition to induction of apoptosis, an antiangiogenic effect of VSVDelta51 was observed in vivo, suggesting a novel tumoricidal mechanism for VSVDelta51. This virus also prevented growth of NPC sphere-forming cells in vitro, showing potential utility in targeting NPC-initiating cells. CONCLUSIONS: Our data represent the first report showing that EBV-positive NPC cells are exquisitely sensitive to VSVDelta51 oncolysis and documenting the successful utilization of this combinatorial regimen as a novel curative therapeutic strategy for NPC.