Dual promoter-controlled oncolytic adenovirus CG5757 has strong tumor selectivity and significant antitumor efficacy in preclinical models.
OBJECTIVE
Transcriptionally controlled oncolytic adenovirus CG5757 is engineered with two tumor-specific promoters from E2F-1 and human telomerase reverse transcriptase genes. This virus has broad anticancer spectrum and higher specificity. The objective of the current study is to show its antitumor selectivity and therapeutic potential.


METHODS
The antitumor specificity of E2F-1 and human telomerase reverse transcriptase promoters was evaluated in a panel of tumor and normal cells. Under the control of these promoters, the tumor-selective expression of E1a and E1b genes was evaluated. Further in vitro antitumor specificity and potency of this virus were characterized by viral replication and cytotoxicity assays followed by a newly developed ex vivo tumor culture assay. Subsequently, in vivo antitumor efficacy and toxicology studies were carried out to assess the therapeutic potential of this oncolytic agent.


RESULTS
In a broad panel of cells, E2F-1 and human telomerase reverse transcriptase promoters were activated in a tumor-selective manner. Under the control of these promoters, expression of E1a and E1b genes appears only in tumor cells. This specificity is extended to viral replication and hence the cytotoxicity in a broad range of cancer cells. Furthermore, CG5757 only replicates in cancer tissues but not in normal tissues that are derived from clinical biopsies. The safety profile was further confirmed in in vivo toxicology studies, and strong efficacy was documented in several tumor xenograft models after CG5757 was given via different routes and regimens.


CONCLUSIONS
CG5757 has strong antitumor selectivity and potency. It has low toxicity and has great potential as a therapeutic agent for different types of cancers.
Li
Yuanhao
Y
Cell Genesys, Inc., South San Francisco, California 94080 and Stanford University, Palo Alto, California, USA. yuanhaoli88@gmail.com
Idamakanti
Neeraja
N
Arroyo
Trini
T
Thorne
Steve
S
Reid
Tony
T
Nichols
Scott
S
VanRoey
Melinda
M
Colbern
Gail
G
Nguyen
Natalie
N
Tam
Orlena
O
Working
Peter
P
Yu
De-Chao
DC
D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000235:genetics*; D015870:Gene Expression; D005814:Genes, Viral / Q000235:genetics; D015316:Genetic Therapy; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009369:Neoplasms / Q000628:therapy*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D019098:Telomerase / Q000235:genetics*; D014779:Virus Replication / Q000235:genetics; D023041:Xenograft Model Antitumor Assays
D004268:DNA-Binding Proteins; D019098:Telomerase