Preclinical Safety and Biodistribution of Adenovirus-Based Cancer Vaccines After Intradermal Delivery

Abstract

The recombinant adenoviral (Ad) vector is being considered as a cancer vaccine platform because it efficiently induces immune responses to tumor antigens by intradermal immunization. The aims of this study were to evaluate the potential toxicities and biodistribution after a single dose or six weekly intradermal doses of Ad2/gp100v2 and Ad2/MART-1v2, which encode tumor-associated antigens gp100 and MelanA/MART-1, respectively. The only dose-related toxicities associated with intradermal administration of these Ad vectors were inflammatory cell infiltrates in the draining lymph nodes and injection sites that persisted 83 days after administration. The biodistribution of Ad DNA as detected by real-time polymerase chain reaction was largely confined to the injection sites and draining lymph nodes of mice treated with either a single dose or multiple doses of Ad vector and in the spleens of mice treated with multiple doses of Ad vector. Adenoviral DNA was transiently detected in the bone marrow, lung, or blood of only one animal for each site and was below the limit of assay quantification (<10 copies/microg DNA). The vector persisted in the skin and lymph nodes as long as 92 days after the last dose. We conclude that Ad vectors delivered by intradermal administration provide a safe, genetic vaccine delivery platform that induces desirable immune responses at the immunization sites and the lymph nodes that, ultimately, result in immune responses specific to the tumor antigens.

Preclinical Evaluation of a Replication-Deficient Recombinant Adenovirus Serotype 5 Vaccine Expressing Guanylate Cyclase C and the PADRE T-helper Epitope

“…Consistent with those results, transduction of BM-MNCs or peripheral blood leukocytes following Ad5 administration yielded transduction efficiencies of 0.0004% and 0%, respectively, suggesting that distribution of vector DNA to the bone marrow is not associated with gene expression within the bone marrow. In a separate study of an Ad2 vector in mice, administration of 5 · 10 8 or 5 · 10 9 vp/animal (20-200 · less than our study) intradermally to C57BL/6 mice yielded detectable vector in bone marrow in <10% of animals 2 days after administration but not at later time points, 24 suggesting that vector persistence in the bone marrow may be dose and/or serotype specific. In other recent published studies, an oncolytic Ad5 (INGN 007) was administered i.v.…”

“…21 Moreover, distribution to draining lymph nodes, liver, and spleen are consistent with other biodistribution studies of adenovirus. [23][24][25] In contrast, the magnitude and duration of persistence of Ad5-GUCY2C-PADRE DNA in the bone marrow is difficult to assess in the context of previous experience, since many studies did not analyze bone marrow. 26,27 An Ad5 or fiber-modified vector (Ad5/ 11, Ad5/35) administered intravenously (i.v.)…”

Evaluation of Long-Term Toxicity of Ad/hIFN-γ, an Adenoviral Vector Encoding the Human Interferon-γGene, in Nonhuman Primates

“…Serum biochemical markers were measured at various times to assess tissue and liver damage. Different local routes of delivery of adenoviral vector have been reported to produce different hematology results: intratumoral and subcutaneous administration caused elevations in certain hematology and serum chemistry parameters (ALT and AST), whereas intradermal delivery did not (Sung et al, 2002;Wildner and Morris, 2002;Plog et al, 2006). Our study showed that intramuscular administration of Ad/hIFN-␥ did not affect serum or urine chemistry profiles at 2-200 times the clinical dose.…”

Adenoviral vectors for gene therapy

“…The favorable properties of adenoviral vectors for gene therapy could also be rationally exploited in the treatment of numerous other diseases or conditions requiring short-term, high-level gene expression. There is also considerable interest in developing adenovirus-based vaccines for infectious and acquired diseases, including AIDS [37], Ebola virus [38], pulmonary tuberculosis [39], and cancer [40].…”