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Updated: Jun 9, 2026
An Efficient Method for Adenovirus Production
Published on: June 10, 2021
Minimal RB-responsive E1A promoter modification to attain potency, selectivity, and transgene-arming capacity in
Juan J Rojas1, Sonia Guedan, Peter F Searle
1Translational Research Laboratory, IDIBELL-Institut Català d'Oncologia, L'Hospitalet de Llobregat, Barcelona, Spain.
Abstract:
Oncolytic adenoviruses are promising anticancer agents due to their ability to self-amplify at the tumor mass. However, tumor stroma imposes barriers difficult to overcome by these agents. Transgene expression is a valuable strategy to counteract these limitations and to enhance antitumor activity. For this purpose, the genetic backbone in which the transgene is inserted should be optimized to render transgene expression compatible with the adenovirus replication cycle and to keep genome size within the encapsidation size limit. In order to design a potent and selective oncolytic adenovirus that keeps intact all the viral functions with minimal increase in genome size, we inserted palindromic E2F-binding sites into the endogenous E1A promoter. The insertion of these sites controlling E1A-Δ24 results in a low systemic toxicity profile in mice. Importantly, the E2F-binding sites also increased the cytotoxicity and the systemic antitumor activity relative to wild-type adenovirus in all cancer models tested. The low toxicity and the increased potency results in improved antitumor efficacy after systemic injection and increased survival of mice carrying tumors. Furthermore, the constrained genome size of this backbone allows an efficient and potent expression of transgenes, indicating that this virus holds promise for overcoming the limitations of oncolytic adenoviral therapy.
Insights
Engineered oncolytic adenoviruses with modified E1A promoters show reduced toxicity and enhanced antitumor activity. This modification improves cancer treatment efficacy and survival rates in preclinical models.
Area of Science:
- Oncolytic virotherapy
- Cancer gene therapy
- Adenovirus engineering
Background:
- Oncolytic adenoviruses show promise for cancer treatment due to tumor self-amplification.
- Tumor stroma presents significant barriers to oncolytic adenovirus efficacy.
- Transgene expression is crucial for overcoming these limitations and enhancing antitumor effects.
Purpose of the Study:
- To design a potent and selective oncolytic adenovirus with minimal genome size increase.
- To optimize transgene expression compatible with the adenovirus replication cycle.
- To enhance antitumor activity and reduce toxicity of oncolytic adenoviruses.
Main Methods:
- Insertion of palindromic E2F-binding sites into the endogenous E1A promoter of the adenovirus.
- Engineering the E1A promoter to control E1A-Δ24 expression.
- Evaluating systemic toxicity, cytotoxicity, and antitumor activity in preclinical cancer models.
Main Results:
- The modified adenovirus exhibited a low systemic toxicity profile in mice.
- E2F-binding sites significantly increased viral cytotoxicity and systemic antitumor activity compared to wild-type adenovirus.
- Improved antitumor efficacy and increased survival rates were observed after systemic injection in tumor-bearing mice.
Conclusions:
- The engineered oncolytic adenovirus demonstrates enhanced potency and reduced toxicity, offering improved therapeutic potential.
- The constrained genome size facilitates efficient and potent transgene expression, addressing key limitations in oncolytic adenoviral therapy.
- This modified adenovirus holds significant promise for overcoming challenges in systemic cancer treatment.
