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A novel E1A-E1B mutant adenovirus induces glioma regression in vivo
Candelaria Gomez-Manzano1, Cristina Balague, Ramon Alemany
1Department of Neuro-Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
Abstract:
Malignant gliomas are the most frequently occurring primary brain tumors and are resistant to conventional therapy. Conditionally replicating adenoviruses are a novel strategy in glioma treatment. Clinical trials using E1B mutant adenoviruses have been reported recently and E1A mutant replication-competent adenoviruses are in advanced preclinical testing. Here we constructed a novel replication-selective adenovirus (CB1) incorporating a double deletion of a 24 bp Rb-binding region in the E1a gene, and a 903 bp deleted region in the E1b gene that abrogates the expression of a p53-binding E1B-55 kDa protein. CB1 exerted a potent anticancer effect in vitro in U-251 MG, U-373 MG, and D-54 MG human glioma cell lines, as assessed by qualitative and quantitative viability assays. Replication analyses demonstrated that CB1 replicates in vitro in human glioma cells. Importantly, CB1 acquired a highly attenuated replicative phenotype in both serum-starved and proliferating normal human astrocytes. In vivo experiments using intracranially implanted D-54 MG glioma xenografts in nude mice showed that a single dose of CB1 (1.5 x 10(8) PFU/tumor) significantly improved survival. Immunohistochemical analyses of expressed adenoviral proteins confirmed adenoviral replication within the tumors. The CB1 oncolytic adenovirus induces a potent antiglioma effect and could ultimately demonstrate clinical relevance and therapeutic utility.
Insights
A novel oncolytic adenovirus, CB1, shows potent anti-glioma effects. This replication-selective adenovirus significantly improved survival in preclinical models, offering therapeutic potential for malignant gliomas.
Area of Science:
- Oncolytic virotherapy
- Gene therapy
- Neuro-oncology
Background:
- Malignant gliomas are aggressive primary brain tumors with limited treatment options.
- Conditionally replicating adenoviruses represent a promising strategy for glioma therapy.
- Previous studies utilized E1B and E1A mutant adenoviruses, with ongoing clinical and preclinical investigations.
Purpose of the Study:
- To construct and evaluate a novel replication-selective adenovirus, CB1, for malignant glioma treatment.
- To assess the in vitro and in vivo efficacy and safety of CB1 against human glioma cells.
Main Methods:
- Construction of CB1 with double deletions in E1a (Rb-binding region) and E1b (p53-binding protein) genes.
- In vitro evaluation of CB1's anticancer effects and replication in human glioma cell lines (U-251 MG, U-373 MG, D-54 MG).
- Assessment of CB1's replication in normal human astrocytes (serum-starved and proliferating).
- In vivo efficacy study using D-54 MG glioma xenografts in nude mice, with survival analysis and immunohistochemistry.
Main Results:
- CB1 demonstrated potent in vitro anticancer activity against multiple human glioma cell lines.
- CB1 replicated effectively in human glioma cells but showed attenuated replication in normal human astrocytes.
- A single dose of CB1 significantly improved survival in mice bearing intracranial D-54 MG glioma xenografts.
- Immunohistochemistry confirmed adenovirus replication within the tumors, supporting the oncolytic mechanism.
Conclusions:
- The novel oncolytic adenovirus CB1 exhibits potent antiglioma activity.
- CB1 demonstrates tumor selectivity, replicating in glioma cells while sparing normal astrocytes.
- CB1 shows significant therapeutic potential and clinical relevance for treating malignant gliomas.
