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Updated: Jan 7, 2026
Paramyxoviruses for Tumor-targeted Immunomodulation: Design and Evaluation Ex Vivo
Published on: January 7, 2019
Beyond oncolytic virotherapy: replication-competent retrovirus vectors for selective and stable transduction of
Charlotte Dalba1, David Klatzmann, Christopher R Logg
1EPIXIS, Paris, France.
Abstract:
As cancer gene therapy employing replication-defective vectors has met with limited clinical success, there is renewed interest in using replication-competent viruses for oncolytic virotherapy. In preclinical and clinical studies, various attenuated vaccine strains and engineered virus vectors are currently being tested for their ability to achieve tumor-selective cell killing. However, significant improvements are still required in tumor selectivity, cytolytic potency, and modulating immune responses to achieve anti-tumor effects without prematurely terminating virus spread. Recently, we have developed murine leukemia virus (MLV)-based replication-competent retrovirus (RCR) vectors for highly efficient, selective, and persistent gene transfer to cancer cells, and found that such vectors may offer significant advantages as oncolytic agents. In a variety of preclinical models, RCR vectors can achieve efficient and persistent gene delivery as the virus replicates throughout an entire tumor mass after inoculation with initial multiplicities of infection as low as 0.001. When engineered to deliver suicide genes, RCR vectors achieve highly efficient and synchronized cell killing triggered by pro-drug administration, both in culture and in tumor models in vivo. Further strategies are being explored to enhance the packaging capacity, efficiency, and specificity of this vector system through the development of semi-replicative RCR vectors, adenovirus-RCR hybrids, and incorporation of tumor targeting mechanisms via modification of binding tropism and transcriptional regulation. In addition, the ability of these vectors to achieve stable transgene expression in infected tumor cells may allow therapeutic applications that move beyond oncolysis per se.
Insights
Replication-competent retrovirus (RCR) vectors show promise for cancer oncolytic virotherapy, offering efficient tumor gene delivery and potent cell killing. Further development aims to enhance tumor selectivity and therapeutic potential beyond direct tumor destruction.
Area of Science:
- Oncolytic Virotherapy
- Retroviral Vector Development
- Cancer Gene Therapy
Background:
- Limited success of replication-defective vectors in cancer gene therapy necessitates alternative approaches.
- Replication-competent viruses are being investigated for enhanced tumor-selective cell killing.
- Current oncolytic virotherapy requires improvements in tumor selectivity, potency, and immune response modulation.
Purpose of the Study:
- To develop and evaluate murine leukemia virus (MLV)-based replication-competent retrovirus (RCR) vectors for oncolytic virotherapy.
- To assess the efficiency, selectivity, and persistence of RCR vectors in gene transfer and tumor cell killing.
- To explore strategies for enhancing RCR vector capabilities for improved cancer treatment.
Main Methods:
- Development of MLV-based RCR vectors for cancer gene transfer.
- Preclinical testing in various cancer models to evaluate gene delivery and replication.
- Engineering RCR vectors to deliver suicide genes for pro-drug-activated cell killing.
- Investigating strategies like semi-replicative vectors, hybrid vectors, and tropism modification.
Main Results:
- RCR vectors demonstrated highly efficient and persistent gene delivery, replicating throughout tumor masses.
- Low initial multiplicities of infection (0.001) were sufficient for effective tumor colonization.
- Engineered RCR vectors achieved synchronized and potent cancer cell killing in vitro and in vivo upon pro-drug administration.
- Stable transgene expression in infected tumor cells suggests potential beyond oncolysis.
Conclusions:
- MLV-based RCR vectors offer significant advantages for oncolytic virotherapy due to efficient, selective, and persistent gene transfer.
- RCR vectors can effectively induce tumor cell death, particularly when engineered with suicide gene systems.
- Ongoing research focuses on enhancing RCR vector systems for broader therapeutic applications in cancer treatment.
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