Lymphokine-activated killer and dendritic cell carriage enhances oncolytic reovirus therapy for ovarian cancer by overcoming antibody neutralization in ascites.
Bottom Line: A major obstacle for effective oncolytic virotherapy is effective delivery of OV to tumor cells.Loading OV onto cell carriers may facilitate virus delivery in the presence of NAb and immune cells which have their own antitumor effector activity are particularly appealing.Reovirus-loaded LAKDC, and to a lesser degree iDC, were able to: (i) protect from NAb and hand-off reovirus for tumor cell killing; (ii) induce a proinflammatory cytokine milieu (IFNɣ, IL-12, IFNα and TNFα) and (iii) generate an innate and specific antitumor adaptive immune response.
Affiliation: Targeted & Biological Therapies Group, Leeds Institute of Molecular Medicine, University of Leeds, United Kingdom.Show MeSH
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Mentions: Having determined that iDC and LAKDC have the potential to deliver oncolytic reovirus to tumors in the presence of NAb to induce virus-mediated cytotoxicity, we next investigated whether these carrier cells could provide additional immune-mediated antitumor effects. As reovirus-loaded LAK cells were unable to shield the virus from neutralization, they were not investigated further (Fig. 3c). To determine the cytotoxic potential of iDC and LAKDC cell carriers alone ± loading with reovirus, in the presence of ascites, chromium release assays were performed. LAKDC, unlike iDC, were cytotoxic against Skov-3 and OVCA433 cells and loading reovirus onto either LAKDC or iDC further increased tumor cell death (Fig. 4a and 4b). We reasoned this additional cytotoxicity following the loading of reovirus could be either direct viral cytotoxicity, or related to an alternative indirect immune mechanism whereby reovirus augments the cytotoxic effects of NK cells.28 To explore these alternatives, the ability of reovirus to enhance LAKDC-induced cytotoxicity was investigated using Daudi as a target cell line, which is known to be resistant to direct reovirus oncolysis. LAKDC-reo were able to kill Daudi targets, but there was no difference between LAKDC and LAKDC-reo cytotoxicity (Fig. 4c), implying that reovirus did not enhance immune LAKDC-mediated cytotoxicity; rather, any increased killing by LAKDC-reo over LAKDC in Figure 4a was probably due to viral, rather than immune effects. Similarly, additional DC-reo cytotoxicity against Daudi targets was not seen (Fig. 4c). Overall, these data support the potential use of LAKDC as carriers of reovirus in vivo for ovarian cancer, to instigate innate immune-mediated cytotoxicity in the presence of NAb, together with reovirus-induced oncolysis.
Affiliation: Targeted & Biological Therapies Group, Leeds Institute of Molecular Medicine, University of Leeds, United Kingdom.