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Systemic image-guided liver cancer radiovirotherapy using dendrimer-coated adenovirus encoding the sodium iodide
Geoffrey K Grünwald1, Alexandra Vetter, Kathrin Klutz
1Department of Internal Medicine II-Campus Grosshadern, University Hospital of Munich, Munich, Germany.
Unlabelled:
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.
Insights
Synthetic dendrimer coating of adenovirus vectors overcomes limitations in gene therapy, enhancing liver cancer treatment through combined radiovirotherapy. This strategy improves NIS gene delivery and therapeutic outcomes.
Area of Science:
- Gene Therapy
- Nanotechnology
- Oncology
Background:
- Adenovirus-mediated gene therapy faces challenges including neutralizing antibodies, CAR receptor expression, and liver sequestration.
- The sodium iodide symporter (NIS) serves as a theranostic gene for imaging and radiotherapy.
Purpose of the Study:
- To investigate if synthetic dendrimer coating of adenovirus vectors can overcome clinical application hurdles.
- To develop adenoviral vectors for combined systemic oncolytic virotherapy and NIS-mediated radiotherapy.
Main Methods:
- Coating replication-deficient and replication-selective adenovirus serotype 5 carrying the hNIS gene with poly(amidoamine) dendrimers generation 5 (PAMAM-G5).
- Evaluating transduction efficacy and tropism using (123)I scintigraphy.
- Assessing therapeutic potential in a liver cancer xenograft mouse model.
Main Results:
- Dendrimer coating partially protected against neutralizing antibodies and enhanced transduction in CAR-negative cells.
- In vivo studies showed reduced hepatic transgene expression and liver toxicity with coated vectors.
- Coated replication-selective adenovirus demonstrated enhanced oncolytic effect and improved survival when combined with (131)I radiotherapy.
Conclusions:
- Synthetic dendrimer coating enables efficient liver detargeting and tumor retargeting of adenoviral vectors.
- This strategy is promising for systemic NIS gene therapy, allowing noninvasive imaging and monitoring.
- The findings provide essential data for planning and individualizing clinical NIS gene therapy trials.
