In vivo bioimaging tracks conditionally replicative adenoviral replication and provides an early indication of viral antitumor efficacy

Abstract

In vivo monitoring of conditionally replicative adenovirus (CRAd) replication and assessing its correlation to CRAd biological effects are necessary for the clinical development of gene therapy. Noninvasive bioimaging is one current approach which can monitor in vivo CRAd replication and functional effect. Here we describe a novel cyclooxygenase-2 (Cox2) promoter-controlled CRAd that was modified to contain firefly luciferase in its E3 region; this modification permitted serial bioluminescence imaging of viral replication in vitro and in vivo. In vitro luciferase expression correlated with viral replication and cytolytic effect. In vivo bioluminescence imaging showed dynamic representation of the viral replication level in athymic nude mice bearing subcutaneous tumor xenografts. Importantly, in vivo luciferase bioluminescence measured 6 days after viral administration significantly correlated with CRAd antitumor effect at day 36. Thus, our system could detect viral replication and predict in vivo therapeutic outcome based on early imaging. Further development of this approach may improve patient safety, enhance clinical trial conduct, and provide mechanistic insight into CRAd function in vivo. (Cancer Sci 2009; 00: 000–000)

Oncolytic adenovirus expressing interferon alpha in a syngeneic Syrian hamster model for the treatment of pancreatic cancer

“…The IFN-expressing vectors (Figure 1) were based on adenovirus type 5 (Ad5) and contained the Ad-ΔE3-ADP structure as we have previously described 21, 22, 28 . Briefly, most of the non-essential adenovirus E3 genes have been deleted (with the exception of the adenovirus death protein (ADP) which is designed to facilitate viral spread and oncolysis) and replaced with the hamster IFN gene 29, 30 .…”

“…As control vectors, the identical adenoviral vectors expressing the firefly luciferase (Luc) gene have been used 21, 31, 32 .…”

“…When tumor nodules reached a diameter of 15 mm, the luciferase-expressing oncolytic adenovirus (RGD-Cox2-ΔE3-ADP-Luc) was injected intratumorally (1×10 10 vp/tumor). Bioluminescence was assessed over a 5 week time-course with an optical imaging system as described previously 28, 34 . The imaging data were displayed as a pseudocolored luminescence intensity image overlaid on a brightfield image of the entire hamster body.…”

Oncolytic adenoviruses targeted to Human Papilloma Virus-positive head and neck squamous cell carcinomas

“…The adenoviral vector plasmids encoding Δ24 and CB016 mutations (pAdΔ24 and pCB016 respectively) [22, 23] (provided by Drs. Ramon Alemany and Cristina Balgué) were recombined with the pAd-ΔE3-ADP-Luc adenoviral backbone as previously described [26]. Briefly, in the pAd-ΔE3-ADP-Luc structure, most of the non-essential adenovirus E3 genes were deleted (with the exception of the adenovirus death protein (ADP) which is designed to facilitate viral spread and oncolysis) and replaced with the luciferase reporter gene [26, 27].…”

“…The Ad 5/3 chimeric fiber replaces the knob region of Ad5 with that of Ad3, while the RGD fiber adds an arginine-glycine-aspartate-containing peptide into the HI loop of the fiber knob domain [28]. The wild type Ad5 (Ad5Wt) and the 5/3 ΔE3-ADP-Luc viruses were utilized as non-selective replicative control vectors [26]. …”