A Novel Chimeric Oncolytic Virus Mediates a Multifaceted Cellular Immune Response in a Syngeneic B16 Melanoma Model.

Background/objectives: Oncolytic virotherapy is a promising approach in cancer immunotherapy. We have previously described a recombinant hybrid oncolytic virus (OV), VSV-NDV, which has a favorable safety profile and therapeutic immunogenicity, leading to direct oncolysis, abscopal effects, and prolonged survival in syngeneic in vivo tumor models. While OVs are known to mediate systemic anti-tumor immune responses, the detailed characterization of local and systemic immune responses to fusogenic oncolytic virotherapy remains unexplored.

Production of recombinant vesicular stomatitis virus-based vectors by tangential flow depth filtration.

Cell culture-based production of vector-based vaccines and virotherapeutics is of increasing interest. The vectors used not only retain their ability to infect cells but also induce robust immune responses. Using two recombinant vesicular stomatitis virus (rVSV)-based constructs, we performed a proof-of-concept study regarding an integrated closed single-use perfusion system that allows continuous virus harvesting and clarification.

Oncolytic virotherapy with chimeric VSV-NDV synergistically supports RIG-I-dependent checkpoint inhibitor immunotherapy.

Unraveling the complexities of the tumor microenvironment (TME) and its correlation with responsiveness to immunotherapy has become a main focus in overcoming resistance to such treatments. Targeting tumor-intrinsic retinoic acid-inducible gene-I (RIG-I), a sensor for viral RNA, was shown to transform the TME from an immunogenically "cold" state to an inflamed, "hot" lesion, which we demonstrated previously to be a crucial mediator of the efficacy of immune checkpoint inhibition with anti-cytotoxic T lymphocyte-associated protein 4 (CTLA-4). In this study, we focus on the chimeric oncolytic virus vesicular stomatitis virus (VSV)-Newcastle disease virus (NDV), comprised of genetic components of VSV and NDV, and we investigate its utility to support tumor-intrinsic RIG-I-dependent therapy with anti-CTLA-4.

Characterization of a quail suspension cell line for production of a fusogenic oncolytic virus.

The development of efficient processes for the production of oncolytic viruses (OV) plays a crucial role regarding the clinical success of virotherapy. Although many different OV platforms are currently under investigation, manufacturing of such viruses still mainly relies on static adherent cell cultures, which bear many challenges, particularly for fusogenic OVs. Availability of GMP-compliant continuous cell lines is limited, further complicating the development of commercially viable products.

Process intensification strategies toward cell culture-based high-yield production of a fusogenic oncolytic virus.

We present a proof-of-concept study for production of a recombinant vesicular stomatitis virus (rVSV)-based fusogenic oncolytic virus (OV), rVSV-Newcastle disease virus (NDV), at high cell densities (HCD). Based on comprehensive experiments in 1 L stirred tank reactors (STRs) in batch mode, first optimization studies at HCD were carried out in semi-perfusion in small-scale cultivations using shake flasks. Further, a perfusion process was established using an acoustic settler for cell retention.