A TRIPLE-MODALITY STRATEGY OF NKT CELL IMMUNOTHERAPY, ONCOLYTIC VIROTHERAPY, AND CHECKPOINT BLOCKADE FOR LUNG CANCER

Abstract

Lung cancer is the leading cause of cancer-related deaths in Canada. Current standard therapies, such as chemotherapy, radiation therapy, or immune checkpoint blockade (ICB) are often ineffective on their own due to severe adverse effects and acquired drug resistance. Therefore, new treatments that are safer and more effective are needed. Recent clinical trials combining ICB with other therapies have demonstrated durable outcomes in some patients with lung cancer. Here I examined the efficacy of combining PD-1 checkpoint blockade with natural killer T (NKT) cell activation therapy and recombinant oncolytic vesicular stomatitis virus (VSV-ΔM51) expressing cytokines IL-12 (VSV-IL-12) or IL-15 (VSV-IL-15), or fusion- associated small transmembrane (FAST) proteins p14 (VSV-p14), p15 (VSV-p15), and p14endp15 (VSV-p14endp15). VSV-p14, VSV-p15, and VSV-p14endp15 demonstrated enhanced immunogenic cell death and killing capacity relative to the parental virus (VSV-GFP) in lung cancer cells, in vitro. Furthermore, VSV-FAST constructs induced PANoptosis and overcame the blockade of multiple programmed cell death pathways to effectively eliminate lung cancer cells. In a genetic mouse model of lung adenocarcinoma, the combination of VSV-p14, VSV-p15, or VSV-p14endp15 with NKT immunotherapy increased overall survival relative to untreated mice. Addition of PD-1 blockade to NKT immunotherapy and VSV-FAST constructs significantly extended the survival over untreated mice. Mixed delivery of VSV-p15 and VSV- IL-12, along with NKT immunotherapy and PD-1 inhibition, had the greatest increase in overall survival of all tested combinations. Maintenance therapy with multiple rounds of VSV-p15/NKT activation/PD-1 blockade also led to significantly enhanced overall survival rates in this model, however some female mice experienced adverse reactions to the treatment. Despite increases in overall survival and increased numbers of NKT cells in the lung and spleen, there were no significant differences in total tumor area or total number of other immune cell populations within the lungs of treated mice compared to untreated mice. We also observed increased VSV neutralizing activity in the serum of treated mice, suggesting potential challenges with repeated systemic VSV treatments. Collectively, our findings demonstrate that the combination of PD-1 blockade with NKT cell immunotherapy and oncolytic VSV-p15/VSV-IL-12 presents a promising strategy for the treatment of lung cancer.