Here, we describe a combination strategy of black phosphorus (BP)-based photothermal therapy together with anti-CD47 antibody (aCD47)-based immunotherapy to synergistically enhance cancer treatment. Tumour resistance to immune checkpoint blockades in most cancers due to immune escape from host surveillance, along with the initiation of metastasis through immunosuppressive cells in the tumour microenvironment, remains a significant challenge for cancer immunotherapy. aCD47, an agent for CD47/SIRPα axis blockade, induces modest phagocytic activity and a low response rate for monotherapy, resulting in failures in clinical trials. We showed that BP-mediated ablation of tumours through photothermal effects could serve as an effective strategy for specific immunological stimulation, improving the inherently poor immunogenicity of tumours, which is particularly useful for enhancing cancer immunotherapy. BP in combination with aCD47 blockade activates both innate and adaptive immunities and promotes local and systemic anticancer immune responses, thus offering a synergistically enhanced effect in suppression of tumour progression and in inducing abscopal effects for inhibition of metastatic cancers. Our combination strategy provides a promising platform in which photothermal agents could help to enhance the therapeutic efficacy of immunotherapy.

Systemic administration of checkpoint inhibitors alone and especially concurrent with intratumoral administration of oncolytic herpesviruses (oHSV) has a major impact on cancer therapy marred by rare failures of healthy organs.Furthermore, tumors vary with respect to susceptibility to oncolytic effects of oHSV. Here we report the construction and properties of 3 families of oncolytic herpes simplex viruses expressing no immunomodulatory genes (T1 series), murine IL-12 (T2 series) or murine or human IL-12 and anti PD-1 antibody (T3 series). We report that insertion of the gene encoding PD-1 Ab significantly augmented the oncolytic activity of oHSV bereft of immunostimulatory genes (T1 series) or expressing IL-12 alone (T2 series). The T3 oHSV expressed IL-12, PD-1 Ab were restricted to the tumor bed whereas the induced IFN-γ accumulated to high levels both in tumor bed and in blood. Furthermore, the T3 oHSV was superior to systemic administration of IL-12 and antibody to PD-1. This report also shows that the oncolytic activity of T3 oHSV in a relatively resistant tumor was enhanced by concurrent intratumoral administration of genetically engineered exosomes carrying miRNA targeting CTLA-4 checkpoint.

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Background Oncolytic viruses (OVs) are considered a promising therapeutic alternative for cancer. However, OVs could activate the host innate immunity, then impair the viral propagation in tumor cells. In this study, we explored the effect of propranolol, a non-selective β-blocker, on the antitumor efficacy of T1012G virus in gastric cancer models. Methods The proliferation of gastric cancer cells treated with monotherapy or combination treatment was detected by CCK8 cell proliferation assay. The effect of propranolol was further evaluated by in vitro viral replication assays. In vivo tumor xenograft experiments were used to observe the effect of combination therapy on gastric cancer growth in mice. The expression levels of viral proteins and interferon responsive genes were detected in the gastric cancer cell lines treated with combined treatment by western blot. The impact of propranolol on IFN-α/β-mediated inhibition of viral propagation and the expression of antiviral gene PKR was detected by viral replication assays and western blot. Results Cell viability assay detected a 97.9% decrease of T1012G IC50 in HGC-27 when it was pretreated with propranolol along with a sevenfold increase of virus titers compared with T1012G only group (P < 0.001). Moreover, propranolol pretreatment caused sustained tumor regression (335.3 ± 36.92 mm3 vs. 1118 ± 210.0 mm3, P < 0.01) and enhanced the viral propagation (fourfold increase, P < 0.01) compared with T1012G only group. Propranolol pretreatment significantly enhanced the p-STAT3 (2.9-fold, P < 0.05) and suppressed p-PKR (65.94% ± 10.11%, P < 0.05) compared with T1012G only group. In addition, propranolol could counteract IFN-α/β-mediated inhibition of viral propagation (compared with IFNα: 5.1-fold, P < 0.001; IFNβ: 4.6-fold, P < 0.01) or enhancement of PKR activation (IFNα: 92.57% ± 1.77%, P < 0.001, IFNβ: 99.34% ± 0.13% decrease, P < 0.001). Conclusions In summary, β-blocker pretreatment could improve the propagation and therapeutic efficacy of T1012G in human gastric cancer by regulating STAT3-PKR signaling cascade, even in the presence of type I IFNs. These data support new strategies of improving the efficacy of OVs in gastric cancer.

In this study, we discovered that two human oral squamous carcinoma cell (OSCC) lines, SCC9 and SCC25, exhibited varied levels of permissivity to oncolytic HSV-1 T1012G replication and the differential virus yields may associate with the constitutive accumulation of two deubiquitinating enzymes USP18 and USP20 in tumor cells. USP18 and USP20 belong to the ubiquitin-specific protease family, mediating the deubiquitination of targets and promoting antiviral responses. Depletion of USP18 or USP20 in SCC9 cells increased T1012G virus yields; overexpression of USP18 or USP20 in SCC25 cells down-regulated T1012G virus replication. In addition, STING as a verified substrate of USP18 and USP20, was found to affect the virus multiplication of T1012G in SCC9 cells. STING knockdown led to an increase in T1012G virus yields in SCC9 cells. Besides, we introduced a deubiquitinating enzyme inhibitor GSK2643943A targeting USP20 and evaluated its effects on viral replication and tumor killing in vitro and in vivo . The results showed that the combination of GSK2643934A and T1012G treatment brought a profound anti-tumor efficacy in mice bearing SCC9 tumors. This report explored factors that play roles in mediating oHSV-1 replication in OSCC tumor cells, facilitating to offer potential targets to improve oHSV-1 oncolytic efficacy and develop candidates of biomarkers to predict the efficiency of oHSV-1 multiplication in tumors.