Preclinical studies of efficacy, biodistribution and clearance of a novel CRAd (driven by SPARC promoter) on disseminated ovarian cancer model

MARIA VERONICA LOPEZ; ANGEL A. RIVERA; DIEGO L. VIALE; ALICIA I. BRAVO; DAVID T. CURIEL; OSVALDO L PODHAJCER

Las Vegas

Congreso; 6th Oncolytic Virus Conference; 2011

Mayo Clinic

In the present study we assessed the efficacy, biodistribution and clearance of a novel CRAd by using a disseminated murine ovarian cancer model. We have previously developed a CRAd that was designed to target both the malignant and the tumor-associated stromal compartment of the tumor mass (Lopez et al, PlosOne 2009). In this CRAd E1A gene was driven by the SPARC promoter (SPPr). In order to further improve specificity and retargeting of that vector, we prepared a new version (Ad-F512-E1DRb 5/3) where SPPr is driving a RB mutated E1A gene and it was pseudotyped with a chimeric Ad5/3 (shaft/knob) fiber. Ad-F512-E1DRb 5/3 showed better litic capacity than its previous CRAd version in ovarian cancer cell lines. Firstly, we determine the intraperitoneal distribution of the non-replicative virus Ad-F512-luc 5/3 and 48 hr later we found luciferase activity only in liver and spleen. Then, we examined the in vivo lytic capacity of Ad-F512-E1DRb 5/3 in a xenograft model of disseminated intraperitoneal ovarian cancer by using a bioluminescent imaging follow up. We found that four i.p. injections of 5 x 1010 v.p eliminated 50% of tumors (assessed by luminescence signal intensity, number and weight of metastases at final point and post-necropsy histological analysis) in animals treated with Ad-F512-E1ADRb 5/3 compared to the controls. We also determine the clearance of the CRAd by injecting the CRAd in xenografted mice and after 0.2, 1, 3, 4 and 18 days post-injection samples of tumor, liver and spleen were extracted (n=2 or 3). We found that the tumor is more efficiently infected that liver or spleen (10 to 16 more adenovirus copies). Moreover, we did not observe virus in liver or spleen by day 18 while in the tumor we can still find the virus. To test CRAd replication in tumors composed of tumor and stromal cells we infected slices of that mixed tumors in vitro. We demonstrated a 30 fold enhanced replication of our CRAd in the presence of stromal cells. Finally, we tested the safety of this CRAd in organs of Syrian hamster. In conclusion, Ad-F512-E1ADRb 5/3 demonstrated a strong killing effect on ovarian cancer models raising its potential use in the clinics.