Oncolytic virotherapy for small-cell lung cancer induces immune infiltration and prolongs survival
Patrick Kellish, … , Frederic J. Kaye, Maria Zajac-Kaye
Patrick Kellish, … , Frederic J. Kaye, Maria Zajac-Kaye
Published April 29, 2019
Citation Information: J Clin Invest. 2019;129(6):2279-2292. https://doi.org/10.1172/JCI121323.
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Research Article Oncology

Oncolytic virotherapy for small-cell lung cancer induces immune infiltration and prolongs survival

Abstract

Oncolytic virotherapy has been proposed as an ablative and immunostimulatory treatment strategy for solid tumors that are resistant to immunotherapy alone; however, there is a need to optimize host immune activation using preclinical immunocompetent models in previously untested common adult tumors. We studied a modified oncolytic myxoma virus (MYXV) that shows high efficiency for tumor-specific cytotoxicity in small-cell lung cancer (SCLC), a neuroendocrine carcinoma with high mortality and modest response rates to immune checkpoint inhibitors. Using an immunocompetent SCLC mouse model, we demonstrated the safety of intrapulmonary MYXV delivery with efficient tumor-specific viral replication and cytotoxicity associated with induction of immune cell infiltration. We observed increased SCLC survival following intrapulmonary MYXV that was enhanced by combined low-dose cisplatin. We also tested intratumoral MYXV delivery and observed immune cell infiltration associated with tumor necrosis and growth inhibition in syngeneic murine allograft tumors. Freshly collected primary human SCLC tumor cells were permissive to MYXV and intratumoral delivery into patient-derived xenografts resulted in extensive tumor necrosis. We confirmed MYXV cytotoxicity in classic and variant SCLC subtypes as well as cisplatin-resistant cells. Data from 26 SCLC human patients showed negligible immune cell infiltration, supporting testing MYXV as an ablative and immune-enhancing therapy.

Authors

Patrick Kellish, Daniil Shabashvili, Masmudur M. Rahman, Akbar Nawab, Maria V. Guijarro, Min Zhang, Chunxia Cao, Nissin Moussatche, Theresa Boyle, Scott Antonia, Mary Reinhard, Connor Hartzell, Michael Jantz, Hiren J. Mehta, Grant McFadden, Frederic J. Kaye, Maria Zajac-Kaye

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Figure 1

MYXV infects and replicates in human SCLC cells.

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MYXV infects and replicates in human SCLC cells. (A) Human SCLC cell lin...
(A) Human SCLC cell lines infected with vMyx-GFP-TdT at 10 MOI demonstrating both early (GFP) and late (TdTomato) gene expression for viral replication at 48 hours for cell line H69 and 24 hours for cell line H1048. Scale bars, 200 μm. (B) Expanded human SCLC and control NHBE cell line infected with vMyx-GFP-TdT at 10 MOI. All SCLC cell lines demonstrate both early (GFP) and late (TdTomato) gene expression for replication at 48 hours whereas control cell lines show negligible permissiveness. Scale bars, 50 μm. (C) Quantification of early gene expression 18 hours after infection (1 MOI). For each cell line, the flow cytometry histograms compare vMyx-GFP-TdT–treated cells relative to control cells (no infection). (D) Replication of MYXV in human SCLC cell lines illustrated by the formation of viral progeny 24 and 48 hours after vMyx-GFP-TdT infection. Results are representative of 3 replicates per group, bar showing mean + SD with all data points. ****P < 0.0001 by 1-way ANOVA and Tukey’s multiple comparison test. (E) Transmission electron microscopy of human SCLC H60 cell line 48 hours after infection with vMyx-M135KO-GFP at 10 MOI. Mature virus (MV), immature particles (IV), and nucleus (N) are labeled. MV is visualized in several areas of the cytoplasm. Inset highlights the indicated region showing MV. Scale bar, 2 μm. (F) Immunogenic cell death (ICD) assay illustrates the increase in ATP release compared with control cells (no infection). Results are representative of 4 replicates per group and time point. Data represent mean + SEM.