IIBBA   05544
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE BUENOS AIRES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Therapeutic Efficacy and Safety Studies of a Novel Oncolytic Adenovirus Active in Tumor-Associated Stromal Cells and Tumor Microenvironment
Autor/es:
VIALE, DL; LOPEZ, MV; CAFFERATA, EG; GOULD, D; CHERNAJOVSKY, Y; CURIEL, DT; PODHAJCER, OL
Lugar:
Seattle, Washington
Reunión:
Encuentro; 14th Annual Meeting of the American Society of Gene and Cell Therapy; 2011
Institución organizadora:
American Society of Gene and Cell Therapy
Resumen:
Human tumors are a heterogeneous mass of malignant cells intermingled with tumor-associated stromal cells that are actively engaged to promote metastatic dissemination. Therefore, a therapy aiming to completely eliminate tumor growth should target both cell types. Wide gene expression analysis identified SPARC as a protumorigenic protein in most human cancers. SPARC is overexpressed in melanoma cells and tumor associated fibroblasts and endothelial cells. We have previously described a conditionally replicative, type 5 adenovirus (CRAd) where E1A expression was driven by a 0.5 kb fragment of the human SPARC promoter (Ad-F512). This CRAd exhibited a strong in vivo therapeutic effect on SB2 melanomas, but its effect was abrogated on mixed tumor models made of SB2 cells and WI-38 fibroblasts (Lopez MV et al, PLOS One, 2009). We aimed to augment Ad-F512 replication capacity by the incorporation to the 0.5 Kb SPARC promoter of genetic elements responsive to cancer-associated environmental conditions, such as inflammation and hypoxia. The new adenoviral vector, named Ad(5)-kBF512HRE, contained 12 NFkB response elements upstream of the 0.5 kb (kB) SPARC promoter and 3 hypoxia response elements (HRE) inside the promoter sequence that did not disrupt specific motifs. This CRAd exhibited an improved transcriptional activity and higher replication rate on three different melanoma cell lines (SB2, Mel-LES and A375N) and in WI-38 cells when placed in hypoxia, in the presence of TNF-α and under both conditions. In vivo, Ad(5)-kBF512HRE was able to eliminate 100% (8/8) of SB2/WI-38 mixed melanoma/fibroblasts tumors in two different assays. However, no therapeutic effect was observed on mice harboring Mel-LES tumors. By flow citometry we established that Mel-LES cells lacked CAR expression but expressed CD46, a candidate receptor of adenovirus type 3. Thus, we genetically modify Ad(5)-kBF512HRE by pseudotyping the virus with a chimeric 5/3 (shaft/knob) fiber. Ad(5/3)-kBF512HRE exhibited a high replication rate and lytic effect on Mel-LES cells in vitro and its administration induced the complete elimination of Mel-LES melanomas in 2/4 mice, while in another mouse a highly reduced tumor growth was observed. In order to evaluate safety parameters, we analyzed CRAd replication on ex-vivo hamster tissue explants that are permissive to adenoviral replication. Ad5-WT highly replicated in lung and spleen hamster explants while we observed no replication of Ad(5/3)-kBF512HRE. In liver tissue explants, we observed 4.5-fold less replication of Ad(5/3)-kBF512HRE compared to Ad5-WT. These data demonstrate the improved lytic capacity of a novel CRAd based on a triple promoter that include enhancer elements responsive to cancer-environmental conditions and a tumor-stroma specific promoter.