625. Viral Shedding after Intratumoral Injection of Adenoviral Vectors to Patients with Cancer
Authors: Gloria González-Aseguinolaza, Maria Ruiz, Cristina Olagüe, Jesus Prieto, Juan Ruiz, Bruno Sangro
Journal: Molecular Therapy (2006)

Background: The access of viral particles to the bloodstream and organic fluids after intratumoral injection of adenoviral vectors for cancer gene therapy may influence their toxicity profile and may result in an environmental risk. Material and Methods: Patients under study were enrolled in two phase I clinical trials evaluating the feasibility and safety of intratumoral injection of an adenoviral vector encoding either human interleukin-12 genes (AdIL-12) or viral thymidine kinase (AdTK). Twenty-one patients with pancreatic (7), colorectal (5), or primary liver (9) malignancies received Ad.IL-12 in doses ranging from 2.5 × 10e10 to 3 × 10e12 viral particles. Eleven patients with pancreatic (4) or hepatocellular (7) carcinomas received Ad-TK in doses ranging from 2 × 10e10 to 2 × 10e11 viral particles. PFU to viral particle ratio were 12.65 and 130 for Ad.IL-12 and AdTK, respectively. In both trials the virus was administered by direct intratumoral injection either percutaneously (into liver tumor nodules) or endoscopically (into primary pancreatic tumors). Serum samples were taken immediately before and 5, 15, 60 and 120 minutes after the end of each intratumoral injection and then 1, 2, 3, 4, 5, 7, 10, 13 and 17 days after. Saliva, sputum, feces, and urine samples were taken before and 1, 2, 3, 4 and 5 days after adenoviral injection. Viral DNA was extracted and real quantitative PCR was performed. The infectivity of the viral particles eventually found in saliva, urine and feces was analyzed in vitro by infection of 293 cells Results: We have found a direct correlation between the dose of virus injected and the intensity and duration of the adenoviral load in serum. An increase in the titers of total and neutralizing antiadenoviral antibodies was also universally observed, although significant differences were observed depending on the age of the patients. Neutralizing antibody titers inversely correlate with age. In those patients that were retreated, a higher serum viral load was observed after the first administration than after second or third injections, probably reflecting sequestration mediated by neutralizing antibodies. Viral particles were detected in some of these patients at day 1 and sporadically day 2, in saliva (12), urine (2) and feces (3). Interestingly, patients that had viral particles in feces were those that had their primary pancreatic tumors injected by endoscopic- ultrasound guidance. Most importantly, none of the samples of saliva, urine and feces that were positive for viral particles showed infectious viral particles (while incubation of the same samples with control virus resulted in only a partial inhibition of its infectivity). In conclusion, our data show that viral shedding largely depends on the dose administered and the route of administration. And they also strongly suggest that no especial containment measures are required for patients receiving intratumoral injection of defective adenovirus.