Oncolytic BHV-1 Is Sufficient to Induce Immunogenic Cell Death and Synergizes with Low-Dose Chemotherapy to Dampen Immunosuppressive T Regulatory Cells

Abstract

Immunogenic cell death (ICD) can switch immunologically “cold” tumors “hot”, making them sensitive to immune checkpoint inhibitor (ICI) therapy. Many therapeutic platforms combine multiple modalities such as oncolytic viruses (OVs) and low-dose chemotherapy to induce ICD and improve prognostic outcomes. We previously detailed many unique properties of oncolytic bovine herpesvirus type 1 (oBHV) that suggest widespread clinical utility. Here, we show for the first time, the ability of oBHV monotherapy to induce bona fide ICD and tumor-specific activation of circulating CD8+ T cells in a syngeneic murine model of melanoma. The addition of low-dose mitomycin C (MMC) was necessary to fully synergize with ICI through early recruitment of CD8+ T cells and reduced infiltration of highly suppressive PD-1+ Tregs. Cytokine and gene expression analyses within treated tumors suggest that the addition of MMC to oBHV therapy shifts the immune response from predominantly anti-viral, as evidenced by a high level of interferon-stimulated genes, to one that stimulates myeloid cells, antigen presentation and adaptive processes. Collectively, these data provide mechanistic insights into how oBHV-mediated therapy modalities overcome immune suppressive tumor microenvironments to enable the efficacy of ICI therapy.

Ferroptosis, pyroptosis and necroptosis in hepatocellular carcinoma immunotherapy: Mechanisms and immunologic landscape (Review)

“…Only a few patients exhibit a response to TKI or ICI treatment alone, while triggering ferroptosis, necroptosis or pyroptosis can alter this response status and improve the response rate of therapy ( 32 , 49 ). Furthermore, ferroptosis, pyroptosis and necroptosis, as three potential novel mechanisms of immunogenic cell death (ICD) ( 50 , 51 ), have been suggested to transform immune 'cold' tumors into immune 'hot' tumors, increasing the sensitivity to ICI therapy, activating CD8 + T cell adaptive immunity and maintaining durable immune memory so that the body gains long-term antitumor immunity ( 52 ). Thus, ferroptosis, pyroptosis and necroptosis are considered three novel potential therapeutic targets to improve the treatment outcomes of HCC ( 49 ).…”