INVESTIGADORES
LOPEZ Maria Veronica
congresos y reuniones científicas
Título:
Incorporation of a mutated E1A and a chimeric 5/3 fiber improved the therapeutic efficacy of a novel CRAd (AdF512) on disseminated ovarian cancer
Autor/es:
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
Reunión:
Congreso; 13th Annual Meeting of the American Society of Gene & Cell Therapy; 2010
Institución organizadora:
American Society of Gene & Cell Therapy
Resumen:
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We have previously developed a new CRAd where E1A
activity is driven by a 0.5 kb fragment of the SPARC gene promoter (SPPr). This
novel CRAd (termed AdF512) was designed to target both the malignant and the
tumor-associated stromal compartment of the tumor mass (Lopez et al, PlosOne
2009). In order to further improve specificity and retargeting, we prepared
different versions of the CRAd where SPPr is driven mutated E1A variants.
Moreover, the CRAd was pseudotyped with a chimeric Ad5/3(shaft/knob) fiber. Ovarian
cancer is one of the leading gynecologic malignancies with no effective
treatment at advanced stages if conventional chemotherapy fails. In the present
study we assessed the different CRAd variants in ovarian cancer models.
Initial studies were designed to establish the
infective capacity of the new vectors. We observed in 3 out of 4 ovarian cancer
cell lines a 2-50 fold increase when Ad-SV40-luc 5/3 was compared to
Ad-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 drove the activity of wild type E1A,
E1A deleted in the Rb binding motif, in the p300 motif or both and measured the
efficacy in the 4 ovarian cancer cell lines. By using the MTS assay we observed
that the better lytic 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 rigorous
preclinical system, which is slices obtained from fresh tissue explants of
human ovarian carcinomas compared to normal ovary. Ad-F512-E1Rb 5/3 replicated
in three out of four human ovarian carcinomas but showed no replication in 3
normal ovary samples. It is important to mention that Ad-wt 5/3 could replicate
in both malignant and normal samples. Histochemical analysis for SPARC
expression levels, presence of stroma and virus replication was also performed
on the fresh explants.
Finally, we examined the in vivo lytic capacity of
Ad-F512-E1Rb 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 1010 v.p inhibited almost 50% of tumor growth, (assessed
using caliper, by signal intensity and by weight) in animals treated with
Ad-F512-E1ARb 5/3 compared to the controls.
In conclusion, Ad-F512-E1ARb 5/3 demonstrated a strong
killing effect on ovarian cancer cells in vitro, and in vivo on disseminated
tumors as well as a high replication capacity in fresh human ovary cancer
explants. Ad-F512-E1ARb 5/3 appears safe since no replication was observed in
normal human ovary raising its potential use in the clinics.