Systemic Image-Guided Liver Cancer Radiovirotherapy Using Dendrimer-Coated Adenovirus Encoding the Sodium Iodide Symporter as Theranostic Gene

Abstract

Currently, major limitations for the clinical application of adenovirus-mediated gene therapy are high prevalence of neutralizing antibodies, widespread expression of the coxsackie-adenovirus receptor (CAR), and adenovirus sequestration by the liver. In the current study, we used the sodium iodide symporter (NIS) as a theranostic gene to investigate whether coating of adenovirus with synthetic dendrimers could be useful to overcome these hurdles in order to develop adenoviral vectors for combination of systemic oncolytic virotherapy and NIS-mediated radiotherapy. Methods: We coated replication-deficient (Ad5-CMV/NIS) (CMV is cytomegalovirus) and replication-selective (Ad5-E1/AFP-E3/NIS) adenovirus serotype 5 carrying the hNIS gene with poly(amidoamine) dendrimers generation 5 (PAMAM-G5) in order to investigate transduction efficacy and altered tropism of these coated virus particles by 123 I scintigraphy and to evaluate their therapeutic potential for systemic radiovirotherapy in a liver cancer xenograft mouse model. Results: After dendrimer coating, Ad5-CMV/NIS demonstrated partial protection from neutralizing antibodies and enhanced transduction efficacy in CAR-negative cells in vitro. In vivo 123 I scintigraphy of nude mice revealed significantly reduced levels of hepatic transgene expression after intravenous injection of dendrimer-coated Ad5-CMV/NIS (dcAd5-CMV/NIS). Evasion from liver accumulation resulted in significantly reduced liver toxicity and increased transduction efficiency of dcAd5-CMV/NIS in hepatoma xenografts. After PAMAM-G5 coating of the replication-selective Ad5-E1/AFP-E3/NIS, a significantly enhanced oncolytic effect was observed after intravenous application (virotherapy) that was further increased by additional treatment with a therapeutic dose of 131 I (radiovirotherapy) and was associated with markedly improved survival. Conclusion: These results demonstrate efficient liver detargeting and tumor retargeting of adenoviral vectors after coating with synthetic dendrimers, thereby representing a promising innovative strategy for systemic NIS gene therapy. Moreover, our study-based on the function of NIS as a theranostic gene allowing the noninvasive imaging of NIS expression by 123 I scintigraphy-provides detailed characterization of in vivo vector biodistribution and localization, level, and duration of transgene expression, essential prerequisites for exact planning and monitoring of clinical gene therapy trials that aim to individualize the NIS gene therapy concept.

Recent therapeutic applications of the theranostic principle with dendrimers in oncology

“…Grünwald et al [53] developed G5 PAMAM dendrimer-coated adenovirus (Ad5-CMV/NIS) encoding sodium iodide symporter as a theranostic gene nanoplatform using the 123 I scintigraphy technique. The authors of this study highlighted the efficient therapeutic potential for systemic radiovirotherapy in a HUH7 liver cancer xenograft mouse model (Fig.…”

Mesenchymal Stem Cell–Mediated, Tumor Stroma–Targeted Radioiodine Therapy of Metastatic Colon Cancer Using the Sodium Iodide Symporter as Theranostic Gene

“…Finally, NIS transgene expression allows the delivery of a robust therapeutic effect through 131 I or 188 Re application (5,20,(31)(32)(33)(34)(35)(36). We have demonstrated the flexibility of this approach in studies using oncolytic viruses and nonviral nanoparticles equipped with the NIS gene to facilitate noninvasive in vivo vector biodistribution imaging as well as 131 I-based radiotherapy after systemic application (37,38).…”

Cancer of the Peripheral Nerve in Neurofibromatosis Type 1

“…Based on reports, measles viruses attach to the cancer cell membrane, kill cancer cells, and cause disease regression [62]. In addition, it is able to take up iodine and thus may be used to visualize infected cancer cells [63].…”