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Updated: Nov 21, 2025
Paramyxoviruses for Tumor-targeted Immunomodulation: Design and Evaluation Ex Vivo
Published on: January 7, 2019
Immunotherapeutic Efficacy of Retargeted oHSVs Designed for Propagation in an Ad Hoc Cell Line
Andrea Vannini1, Valerio Leoni1, Mara Sanapo1
1Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, 40126 Bologna, Italy.
Abstract:
Our laboratory has pursued the generation of cancer-specific oncolytic herpes simplex viruses (oHSVs) which ensure high efficacy while maintaining a high safety profile. Their blueprint included retargeting to a Tumor-Associated Antigen, e.g., HER2, coupled to detargeting from natural receptors to avoid off-target and off-tumor infections and preservation of the full complement of unmodified viral genes. These oHSVs are "fully virulent in their target cancer cells". The 3rd generation retargeted oHSVs carry two distinct retargeting moieties, which enable infection of a producer cell line and of the target cancer cells, respectively. They can be propagated in an ad hoc Vero cell derivative at about tenfold higher yields than 1st generation recombinants, and more effectively replicate in human cancer cell lines. The R-335 and R-337 prototypes were armed with murine IL-12. Intratumorally-administered R-337 conferred almost complete protection from LLC-1-HER2 primary tumors, unleashed the tumor microenvironment immunosuppression, synergized with the checkpoint blockade and conferred long-term vaccination against distant challenge tumors. In summary, the problem intrinsic to the propagation of retargeted oHSVs-which strictly require cells positive for targeted receptors-was solved in 3rd generation viruses. They are effective as immunotherapeutic agents against primary tumors and as antigen-agnostic vaccines.
Insights
Third-generation oncolytic herpes simplex viruses (oHSVs) demonstrate enhanced cancer-specific targeting and replication. These novel oHSVs effectively treat primary tumors and act as vaccines, improving safety and efficacy.
Area of Science:
- Oncolytic virotherapy
- Cancer immunotherapy
- Virology
Background:
- Development of oncolytic herpes simplex viruses (oHSVs) for cancer treatment.
- Need for improved tumor specificity and safety profiles in oHSVs.
- Challenges in propagating retargeted oHSVs due to receptor dependence.
Purpose of the Study:
- To engineer third-generation oHSVs with dual retargeting moieties for enhanced cancer cell infection and propagation.
- To evaluate the therapeutic efficacy and immunotherapeutic potential of these novel oHSVs.
- To address limitations in the production of retargeted oHSVs.
Main Methods:
- Designing oHSVs with retargeting to tumor-associated antigens (e.g., HER2) and detargeting from natural receptors.
- Utilizing a specialized Vero cell derivative for oHSV propagation.
- Arming oHSVs (R-335, R-337) with murine IL-12 for enhanced immunomodulation.
- Assessing intratumoral administration efficacy in preclinical cancer models (LLC-1-HER2).
Main Results:
- Third-generation oHSVs exhibit improved replication in human cancer cell lines and higher propagation yields.
- Intratumoral administration of R-337 led to significant tumor regression and protection against primary tumors.
- oHSVs modulated the tumor microenvironment, reduced immunosuppression, and synergized with checkpoint blockade therapy.
- Treated animals developed long-term vaccination effects against distant tumors.
Conclusions:
- Third-generation retargeted oHSVs overcome propagation challenges, enabling efficient production.
- These oHSVs are effective immunotherapeutic agents against primary tumors.
- The engineered oHSVs demonstrate potential as antigen-agnostic vaccines for long-term cancer immunity.
