Measles virus causes immunogenic cell death in human melanoma

Oncolytic viruses (OV) are promising treatments for cancer, with several currently undergoing testing in randomised clinical trials. Measles virus (MV) has not yet been tested in models of human melanoma. This study demonstrates the efficacy of MV against human melanoma. It is increasingly recognised that an essential component of therapy with OV is the recruitment of host anti-tumour immune responses, both innate and adaptive. MV-mediated melanoma cell death is an inflammatory process, causing the release of inflammatory cytokines including type-1 interferons and the potent danger signal HMGB1. Here, using human in vitro models, we demonstrate that MV enhances innate antitumour activity, and that MV-mediated melanoma cell death is capable of stimulating a melanoma-specific adaptive immune response

Oncolytic reovirus as a combined antiviral and anti-tumour agent for the treatment of liver cancer

Objective: Oncolytic viruses (OVs) represent promising, proinflammatory cancer treatments. Here, we explored whether OV-induced innate immune responses could simultaneously inhibit HCV while suppressing hepatocellular carcinoma (HCC). Furthermore, we extended this exemplar to other models of virus-associated cancer. Design and results: Clinical grade oncolytic orthoreovirus (Reo) elicited innate immune activation within primary human liver tissue in the absence of cytotoxicity and independently of viral genome replication. As well as achieving therapy in preclinical models of HCC through the activation of innate degranulating immune cells, Reo-induced cytokine responses efficiently suppressed HCV replication both in vitro and in vivo. Furthermore, Reo-induced innate responses were also effective against models of HBV-associated HCC, as well as an alternative endogenous model of Epstein–Barr virus-associated lymphoma. Interestingly, Reo appeared superior to the majority of OVs in its ability to elicit innate inflammatory responses from primary liver tissue. Conclusions: We propose that Reo and other select proinflammatory OV may be used in the treatment of multiple cancers associated with oncogenic virus infections, simultaneously reducing both virus-associated oncogenic drive and tumour burden. In the case of HCV-associated HCC (HCV-HCC), Reo should be considered as an alternative agent to supplement and support current HCV-HCC therapies, particularly in those countries where access to new HCV antiviral treatments may be limited

BRAF- and MEK-targeted small molecule inhibitors exert enhanced antimelanoma effects in combination with oncolytic reovirus through ER stress

Reovirus type 3 (Dearing) (RT3D) infection is selective for cells harboring a mutated/activated RAS pathway. Therefore, in a panel of melanoma cell lines (including RAS mutant, BRAF mutant and RAS/BRAF wild-type), we assessed therapeutic combinations that enhance/suppress ERK1/2 signaling through use of BRAF/MEK inhibitors. In RAS mutant cells, the combination of RT3D with the BRAF inhibitor PLX4720 (paradoxically increasing ERK1/2 signaling in this context) did not enhance reoviral cytotoxicity. Instead, and somewhat surprisingly, RT3D and BRAF inhibition led to enhanced cell kill in BRAF mutated cell lines. Likewise, ERK1/2 inhibition, using the MEK inhibitor PD184352, in combination with RT3D resulted in enhanced cell kill in the entire panel. Interestingly, TCID 50 assays showed that BRAF and MEK inhibitors did not affect viral replication. Instead, enhanced efficacy was mediated through ER stress-induced apoptosis, induced by the combination of ERK1/2 inhibition and reovirus infection. In vivo, combined treatments of RT3D and PLX4720 showed significantly increased activity in BRAF mutant tumors in both immune-deficient and immune-competent models. These data provide a strong rationale for clinical translation of strategies in which RT3D is combined with BRAF inhibitors (in BRAF mutant melanoma) and/or MEK inhibitors (in BRAF and RAS mutant melanoma)

Progress in clinical oncolytic virus-based therapy for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) carries a dismal prognosis, with advanced disease being resistant to both radiotherapy and conventional cytotoxic drugs, whilst anti-angiogenic drugs are marginally efficacious. Oncolytic viruses (OVs) offer the promise of selective cancer therapy through direct and immune-mediated mechanisms. The premise of OVs lies in their preferential genomic replication, protein expression and productive infection of malignant cells. Numerous OVs are being tested in preclinical models of HCC, with good evidence of direct and immune-mediated antitumour efficacy. Efforts to enhance the performance of these agents have concentrated on engineering OV cellular specificity, immune evasion, enhancing anti-tumour potency and improving delivery. The lead agent in HCC clinical trials, JX-594, a recombinant Wyeth strain vaccinia virus, has demonstrated evidence for significant benefit and earned orphan drug status. Thus, JX-594 appears to be transcending the barrier between novel laboratory science and credible clinical therapy. Relatively few other OVs have entered clinical testing, a hurdle that must be overcome if significant progress is to be made in this field. This review summarizes the preclinical and clinical experience of OV therapy in the difficult-to-treat area of HCC