Incorporation of a Mutated E1A and a Chimeric 5/3 Fiber Improved the Therapeutic Ef cacy of a Novel CRAd (Ad-F512) on Disseminated Ovarian Cancer

MARIA VERONICA LOPEZ; ANGEL A. RIVERA; LORENA BENEDETTI; DIEGO L. VIALE; KRISTOPHER J KIMBALL; MINGHUI WANG; ALICIA I BRAVO; CHRISTINE DORVAULT; JOANNE DOUGLAS; ZENG B ZHU; RONALD D ALVAREZ; DAVID T CURIEL; OSVALDO L PODHAJCER

Marriott Wardman Park Hotel, Washington, DC, USA

Congreso; 13th Annual Meeting of The American Society of Gene and Cell Therapy; 2010

American Society of Gene and Cell Therapy

We have previously developed a new CRAd where E1A activityis driven by a 0.5 kb fragment of the SPARC gene promoter (SPPr).This novel CRAd (termed Ad-F512) was designed to target boththe malignant and the tumor-associated stromal compartment of thetumor mass (Lopez et al, PlosOne 2009). In order to further improvespecificity and retargeting, we prepared different versions of theCRAd where SPPr is driven mutated E1A variants. Moreover, theCRAd was pseudotyped with a chimeric Ad5/3(shaft/knob)  ber.Ovarian cancer is one of the leading gynecologic malignancies with noeffective treatment at advanced stages if conventional chemotherapyfails. In the present study we assessed the different CRAd variantsin ovarian cancer models.Initial studies were designed to establish the infective capacityof the new vectors. We observed in 3 out of 4 ovarian cancer celllines a 2-50 fold increase when Ad-SV40-luc 5/3 was compared toAd-SV40-luc 5/5. Moreover, Ad-F512-luc 5/3 was as active as Ad-SV40-luc 5/3. Next, we constructed four CRAds where SPPr drovethe activity of wild type E1A, E1A deleted in the Rb binding motif,in the p300 motif or both and measured the eficacy in the 4 ovariancancer cell lines. By using the MTS assay we observed that the betterlytic capacity was obtained with the CRAd containing the Rb deletion(Ad-F512-E1Rb 5/3).In order to establish the potential clinical utility of Ad-F512-E1Rb 5/3 we also assayed its replication capacity in a most rigorouspreclinical system, which is slices obtained from fresh tissue explantsof human ovarian carcinomas compared to normal ovary. Ad-F512-E1Rb 5/3 replicated in three out of four human ovarian carcinomasbut showed no replication in 3 normal ovary samples. It is importantto mention that Ad-wt 5/3 could replicate in both malignant andnormal samples. Histochemical analysis for SPARC expressionlevels, presence of stroma and virus replication was also performedon the fresh explants.Finally, we examined the in vivo lytic capacity of Ad-F512-E1Rb5/3 in a xenograft model of disseminated intraperitoneal ovariancancer by using a bioluminescent imaging follow up. We found thatfour i.p. injections of 1010 v.p inhibited almost 50% of tumor growth,(assessed using caliper, by signal intensity and by weight) in animalstreated with Ad-F512-E1ARb 5/3 compared to the controls.In conclusion, Ad-F512-E1ARb 5/3 demonstrated a strong killingeffect on ovarian cancer cells in vitro, and in vivo on disseminatedtumors as well as a high replication capacity in fresh human ovarycancer explants. Ad-F512-E1ARb 5/3 appears safe since noreplication was observed in normal human ovary raising its potentialuse in the clinics.