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Introduction: Immune checkpoint inhibitors (ICI) have dramatically improved the outcome for cancer patients across multiple tumor types. However the response rates to ICI monotherapy remain relativ...

BackgroundOncolytic reovirus therapy for cancer induces a typical antiviral response to this RNA virus, including neutralizing antibodies. Concomitant treatment with cytotoxic chemotherapies has been hypothesized to improve the therapeutic potential of the virus. Chemotherapy side effects can include immunosuppression, which may slow the rate of the antiviral antibody response, as well as potentially make the patient more vulnerable to viral infection.MethodReovirus neutralizing antibody data were aggregated from separate phase I clinical trials of reovirus administered as a single agent or in combination with gemcitabine, docetaxel, carboplatin and paclitaxel doublet or cyclophosphamide. In addition, the kinetics of individual antibody isotypes were profiled in sera collected in these trials.ResultsThese data demonstrate preserved antiviral antibody responses, with only moderately reduced kinetics with some drugs, most notably gemcitabine. All patients ultimately produced an effective neutralizing antibody response.ConclusionPatients’ responses to infection by reovirus are largely unaffected by the concomitant drug treatments tested, providing confidence that RNA viral treatment or infection is compatible with standard of care treatments.

Purpose: The prevention and treatment of metastatic sarcoma are areas of significant unmet need. Immune checkpoint inhibitor monotherapy has shown little activity in sarcoma and there is great interest in identifying novel treatment combinations that may augment responses. In vitro and in vivo, we investigated the potential for an oncolytic vaccinia virus (GLV-1h68) delivered using isolated limb perfusion (ILP) to promote antitumor immune responses and augment response to PD-1 blockade in sarcoma. Experimental Design: In an established animal model of extremity sarcoma, we evaluated the potential of locoregional delivery of a vaccinia virus (GLV-1h68) alongside biochemotherapy (melphalan/TNFα) in ILP. Complementary in vitro assays for markers of immunogenic cell death were performed in sarcoma cell lines. Results: PD-1 monotherapy had minimal efficacy in vivo, mimicking the clinical scenario. Pretreatment with GLV-1h68 delivered by ILP (viral ILP) significantly improved responses. Furthermore, when performed prior to surgery and radiotherapy, viral ILP and PD-1 blockade prevented both local and distant relapse, curing a previously treatment-refractory model. Enhanced therapy was associated with marked modulation of the tumor microenvironment, with an increase in the number and penetrance of intratumoral CD8+ T cells and expansion and activation of dendritic cells. GLV-1h68 was capable of inducing markers of immunogenic cell death in human sarcoma cell lines. Conclusions: Viral ILP augments the response to PD-1 blockade, transforming this locoregional therapy into a potentially effective systemic treatment for sarcoma and warrants translational evaluation.

There are currently numerous oncolytic viruses undergoing clinical trial evaluation in cancer patients and one agent,Talimogene laherparepvec, has been approved for the treatment of malignant melanoma. This progress highlights the huge clinical potential of this treatment modality, and the focus is now combining these agents with conventional anti-cancer treatments or agents that enhance viral replication, and thereby oncolysis, in the tumour microenvironment. We evaluated the combination of reovirus with rapamycin in B16F10 cell, a murine model of malignant melanoma, based on potential mechanisms by which mTOR inhibitors might enhance viral oncolysis. Rapamycin was not immunomodulatory in that it had no effect on the generation of an anti-reovirus neutralising antibody response in C57/black 6 mice. The cell cycle effects of reovirus (increase G0/G1 fraction) were unaffected by concomitant or sequential exposure of rapamycin, However, rapamycin attenuated viral replication if given prior or concomitantly with reovirus and similarly reduced reovirus-induced apoptotic cell death annexin V/PI and caspase 3/7 activation studies. We found clear evidence of synergistic antitumour effects of the combination both in vitro and in vivo, which was sequence dependent only in the in vitro setting. In conclusion, we have demonstrated synergistic anti-tumour efficacy of reovirus and rapamycin combination.

Introduction:RP1 and RP2 are novel, enhanced potency oncolytic versions of HSV1 engineered to express human GM-CSF and the gibbon ape leukemia virus membrane R- glycoprotein (GALV-GP R-), providing constitutive fusion activity and increased immunogenic cell death. RP2 further expresses an anti-CTLA-4 antibody-like molecule. Murine versions of RP1 and RP2 exhibited synergy in combination with anti-mouse-PD-1 leading to enhanced regression of both injected and un-injected tumors in mice (Thomas et al JITC 2019). RP1 and RP2 are currently being evaluated in clinical trials in a range of solid tumors alone and combined with anti-PD1 therapy, where deep and durable responses have been demonstrated (SITC 2020). Here we present biomarker data from the Phase 1/2 clinical trial of RP1 alone and combined with nivolumab (NCT03767348) and from the Phase 1 portion of the clinical trial with RP2 alone (NCT04336241). Methods: In the Phase 1/2 studies tumor biopsies and peripheral blood mononuclear samples (PBMCs) were collected at screening and at D43 for biomarker analysis, after combination therapy with nivolumab for RP1 and following single agent treatment for RP2. Immunohistochemistry (IHC) was performed for CD8 (SP57 clone, Ventana) and for PD-L1 (28-8 clone, pharmDx assay). Gene expression was analysed using NanoString to assess effects on a range of genes. The tumor inflammation signature score (TIS) was also calculated. Results:Preliminary Phase 1/2 biomarker data from paired tumor biopsies include the following: Immunohistochemistry for CD8 and PD-L1 (n=30) indicated robust and increased infiltration of CD8+ T cells and PD-L1 expression, both after combined treatment with RP1 and nivolumab and after single agent RP2 across different tumor types, and including reversal of T cell exclusion following prior combined treatment with ipilimumab and nivolumab in melanoma. Gene expression analysis (n=15) demonstrated a significant increase in the expression levels of genes associated with innate and adaptive immune activation and genes previously reported to be associated with responsiveness to anti-PD1 therapy, particularly CD8, CXCL9, CD27 and TIGIT, as well as consistently increased TIS. Conclusion:Consistent with the pre-clinical data, preliminary clinical biomarker data indicate substantial increase in CD8 T cell infiltration and PD-L1 expression, as well as increased TIS score in the majority of patients treated with RP2 alone or RP1 and nivolumab combination. Particularly marked effects were seen in some patients with clinical responses which occurred independent of both baseline PD-L1 and prior anti-PD1 therapy status, which suggests potential broad utility of the RP1/2 treatment approach in igniting an anti-tumor immune response. Tumor mutation burden analysis and T cell receptor sequencing are currently underway and further updates of the dataset will be presented. Citation Format: Kevin J. Harrington, Francesca Aroldi, Joseph J. Sacco, Mohammed M. Milhem, Brendan D. Curti, Ari M. Vanderwalde, Scott Baum, Adel Samson, Anna C. Pavlick, Jason A. Chesney, Jiaxin Niu, Terence D. Rhodes, Tawnya L. Bowles, Robert Conry, Anna Olsson-Brown, Douglas E. Laux, Pablo Nenclares, Lavita Menezes, Alex Deterding, Victoria Roulstone, Joan Kyula, Suzanne Thomas, Praveen K. Bommareddy, Selda Samakoglu, Andrea Pirzkall, Robert S. Coffin, Mark R. Middleton. Clinical biomarker studies with two fusion-enhanced versions of oncolytic HSV (RP1 and RP2) alone and in combination with nivolumab in cancer patients indicate potent immune activation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB180.

Drugs that mobilise the immune system against cancer are dramatically improving care for many people. Dying cancer cells play an active role in inducing anti‐tumour immunity but not every form of death can elicit an immune response. Moreover, resistance to apoptosis is a major problem in cancer treatment and disease control. While the term “immunogenic cell death” is not fully defined, activation of receptor‐interacting serine/threonine‐protein kinase 1 (RIPK1) can induce a type of death that mobilises the immune system against cancer. However, no clinical treatment protocols have yet been established that would harness the immunogenic potential of RIPK1. Here, we report the first pre‐clinical application of an in vivo treatment protocol for soft‐tissue sarcoma that directly engages RIPK1‐mediated immunogenic cell death. We find that RIPK1‐mediated cell death significantly improves local disease control, increases activation of CD8+ T cells as well as NK cells, and enhances the survival benefit of immune checkpoint blockade. Our findings warrant a clinical trial to assess the survival benefit of RIPK1‐induced cell death in patients with advanced disease at limb extremities., The pathways that initiate and execute immunogenic cell death are complex, genetically encoded, and subject to significant regulation. This study focusses on the possibility to engage RIPK1‐mediated immunogenic cell death for the treatment of soft tissue sarcomas that occur at limb extremities.

Advanced extremity melanoma and sarcoma present a significant therapeutic challenge, requiring multimodality therapy to treat or even palliate disease. These aggressive tumours are relatively chemo-resistant, therefore new treatment approaches are urgently required. We have previously reported on the efficacy of oncolytic virotherapy (OV) delivered by isolated limb perfusion. In this report, we have improved therapeutic outcomes by combining OV with radiotherapy. In vitro, the combination of oncolytic vaccinia virus (GLV-1h68) and radiotherapy demonstrated synergistic cytotoxicity. This effect was not due to increased viral replication, but mediated through induction of intrinsic apoptosis. GLV-1h68 therapy downregulated the anti-apoptotic BCL-2 proteins (MCL-1 and BCL-XL) and the downstream inhibitors of apoptosis, resulting in cleavage of effector caspases 3 and 7. In an in vivo ILP model, the combination of OV and radiotherapy significantly delayed tumour growth and prolonged survival compared to single agent therapy. These data suggest that the virally-mediated down-regulation of anti-apoptotic proteins may increase the sensitivity of tumour cells to the cytotoxic effects of ionizing radiation. Oncolytic virotherapy represents an exciting candidate for clinical development when delivered by ILP. Its ability to overcome anti-apoptotic signals within tumour cells points the way to further development in combination with conventional anti-cancer therapies.

// Grainne McEntee 1 , Joan N. Kyula 1 , David Mansfield 1 , Henry Smith 1, 2 , Michelle Wilkinson 1, 2 , Claire Gregory 1 , Victoria Roulstone 1 , Matt Coffey 3 , Kevin J. Harrington 1 1 Targeted Therapy Team, the Institute of Cancer Research, London, UK 2 Sarcoma/Melanoma Unit, Department of Academic Surgery, Royal Marsden Hospital NHS Foundation Trust, London, UK 3 Oncolytics Biotech Inc., Calgary, Canada Correspondence to: Kevin J. Harrington, email: Kevin.Harrington@icr.ac.uk Keywords: reovirus, radiotherapy, melanoma, CUG2, apoptosis Received: January 18, 2016 Accepted: June 09, 2016 Published: July 1, 2016 ABSTRACT Oncolytic viruses selectively target and replicate in cancer cells, providing us with a unique tool with which to target and kill tumour cells. These viruses come from a diverse range of viral families including reovirus type 3 Dearing (RT3D), a non-pathogenic human double-stranded RNA oncolytic virus, which has been shown to be an effective therapeutic agent, both as a mono-therapy and in combination with traditional chemotherapeutic drugs. This study investigated the interaction between RT3D and radiotherapy in melanoma cell lines with a BRAF mutant, Ras mutant or BRAF/Ras wild type genotype. The data indicates that RT3D combined with radiotherapy significantly increased cytotoxicity relative to either single agent, independent of genotype, both in vitro and in vivo . The mechanism of enhanced cytotoxicity was dependent on an increase in viral replication, mediated by CUG2 up-regulation and subsequent down-regulation of pPKR and p-eIF2α, leading to the activation of mitochondrial apoptotic signalling resulting in increased cell death.

Improvements in cancer survival mean that long-term toxicities are being increasingly recognised that contribute to the morbidity of cancer survivorship. Late adverse effects (LAEs) in normal tissues after radiotherapy (RT) are characterized by vascular dysfunction and fibrosis leading to volume loss and tissue contracture. For example, irradiation of free flaps used for immediate breast reconstruction after mastectomy results in LAEs that distort the reconstructed breast, necessitating salvage reconstruction long after cancer treatment is complete. We evaluated the efficacy of lentiviral superoxide dismutase 2 (LVSOD2) and connective tissue growth factor (CTGF) shRNA in reducing the severity of LAEs using a novel animal model of free flap LAEs. Vectors were delivered by intra-arterial injection, ex vivo, to target the vascular compartment. LVSOD2 and LVshCTGF monotherapy prior to irradiation resulted in significant preservation of flap volume or reduction in skin contracture, respectively. Flaps transduced with combination therapy experienced significant improvements in both volume loss and skin contracture. Both therapies significantly reduced the fibrotic burden after irradiation. LAEs were associated with impaired vascular perfusion, loss of endothelial permeability and stromal hypoxia that were further reversed in the described treatment model. Using a model of tumour recurrence within transduced flaps we showed that SOD2 over-expression in normal tissues did not compromise the cytotoxic efficacy of RT against tumour cells but instead, paradoxically, appeared to enhance it. LVSOD2 and LVshCTGF combination therapy by targeted, intravascular delivery reduced LAE severities in normal tissues without compromising the efficacy of RT and warrants translational evaluation as a free flap-targeted gene therapy.

Isolated limb perfusion (ILP) is a treatment for advanced extremity sarcoma and in-transit melanoma. Advancing this procedure by investigating the addition of novel agents, such as cancer-selective oncolytic viruses, may improve both the therapeutic efficacy of ILP and the tumour-targeted delivery of oncolytic virotherapy. Standard in vitro assays were used to characterise single agent and combinatorial activities of melphalan, tumour necrosis factor-alpha (TNF-α) and Lister strain vaccinia virus (GLV-1h68) against BN175 rat sarcoma cells. An orthotopic model of advanced extremity sarcoma was used to evaluate survival of animals after ILP with combinations of TNF-α, melphalan and GLV-1h68. We investigated the efficiency of viral tumour delivery by ILP compared to intravenous therapy, the locoregional and systemic biodistribution of virus after ILP, and the effect of mode of administration on antibody response. The combination of melphalan and GLV-1h68 was synergistic in vitro. The addition of virus to standard ILP regimens was well tolerated and demonstrated superior tumour targeting compared to intravenous administration. Triple therapy (melphalan/TNF-α/GLV-1h68) resulted in increased tumour growth delay and enhanced survival compared to other treatment regimens. Live virus was recovered in large amounts from perfused regions, but in smaller amounts from systemic organs. The addition of oncolytic vaccinia virus to existing TNF-α/melphalan-based ILP strategies results in survival advantage in an immunocompetent rat model of advanced extremity sarcoma. Virus administered by ILP has superior tumour targeting compared to intravenous delivery. Further evaluation and clinical translation of this approach is warranted.

A number of oncolytic viruses have shown single agent clinical activity and evidence of clinical synergy with immune checkpoint blockade. However, not all patients respond, and as yet most of the promising clinical data have been generated in patients with melanoma. With the objective of maximally activating a patient's immune system against their own cancer which will then provide enhanced synergy with anti-PD1/L1 blockade, we developed a new oncolytic immunotherapy platform based on herpes simplex virus (HSV). This has the dual objectives of killing tumor to provide abundant release of tumor antigens, and potently activating immune responses against these antigens once released. To augment the natural ability of the virus to kill tumors and activate the immune system, these viruses are each armed with multiple therapeutic genes. Initially, we screened 29 new clinical strains of HSV isolated from volunteers who suffer from cold sores across a panel of human tumor cell lines to select a candidate for further development. This strain was then engineered to provide tumor selective replication (deletion of the genes encoding ICP34.5 and ICP47) and to express a potent fusogenic glycoprotein (GALV-GP R-). These modifications greatly enhance both local and systemic antitumor effects, increase immunogenic cell death, potently activate anti-tumor immunity, and are synergistic with PD-1 blockade in pre-clinical models. A virus expressing both GALV-GP R- and human GM-CSF is currently in a Phase 1/2 clinical trial in approximately 150 patients as a single-agent and combined with PD1 blockade in four solid tumor types. Further viruses express additional immune-activating proteins expected to act at the site of immune response initiation in tumors and draining lymph nodes, in particular an anti-CTLA-4 antibody-like molecule and immune co-stimulatory pathway-activating ligands. Each of these demonstrated increased activity in pre-clinical models, particularly an enhanced anenestic effect. The anti-CTLA-4 expressing virus (RP2) is targeted to enter clinical trials in the first half of 2019. Thus, a modular approach to oncolytic immunotherapy development can rapidly generate multiple clinical candidates with multiple mechanisms of action intended to act synergistically with other approaches to cancer therapy. The latest pre-clinical data utilizing this platform will be presented. Citation Format: Suzanne Thomas, Linta Juncheria, Victoria Roulstone, Joan N. Kyula, Howard L. Kaufman, Kevin J. Harrington, Robert S. Coffin. Development & characterization of a new oncolytic immunotherapy platform based on herpes simplex virus type 1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1470.

Background and purpose We previously reported a therapeutic strategy comprising replication-defective NIS-expressing adenovirus combined with radioiodide, external beam radiotherapy (EBRT) and DNA repair inhibition. We have now evaluated NIS-expressing oncolytic measles virus (MV-NIS) combined with NIS-guided radioiodide, EBRT and specific checkpoint kinase 1 (Chk1) inhibition in head and neck and colorectal models. Materials and methods Anti-proliferative/cytotoxic effects of individual agents and their combinations were measured by MTS, clonogenic and Western analysis. Viral gene expression was measured by radioisotope uptake and replication by one-step growth curves. Potential synergistic interactions were tested in vitro by Bliss independence analysis and in in vivo therapeutic studies. Results EBRT and MV-NIS were synergistic in vitro . Furthermore, EBRT increased NIS expression in infected cells. SAR-020106 was synergistic with EBRT, but also with MV-NIS in HN5 cells. MV-NIS mediated 131 I-induced cytotoxicity in HN5 and HCT116 cells and, in the latter, this was enhanced by SAR-020106. In vivo studies confirmed that MV-NIS, EBRT and Chk1 inhibition were effective in HCT116 xenografts. The quadruplet regimen of MV-NIS, virally-directed 131 I, EBRT and SAR-020106 had significant anti-tumour activity in HCT116 xenografts. Conclusion This study strongly supports translational and clinical research on MV-NIS combined with radiation therapy and radiosensitising agents.

The management of locally advanced or recurrent extremity sarcoma often necessitates multimodal therapy to preserve a limb, of which isolated limb perfusion (ILP) is a key component. However, with standard chemotherapeutic agents used in ILP, the duration of response is limited. Novel agents or treatment combinations are urgently needed to improve outcomes. Previous work in an animal model has demonstrated the efficacy of oncolytic virotherapy when delivered by ILP and, in this study, we report further improvements from combining ILP‐delivered oncolytic virotherapy with radiation and surgical resection. In vitro, the combination of radiation with an oncolytic vaccinia virus (GLV‐1h68) and melphalan demonstrated increased cytotoxicity in a panel of sarcoma cell lines. The effects were mediated through activation of the intrinsic apoptotic pathway. In vivo, combinations of radiation, oncolytic virotherapy and standard ILP resulted in delayed tumour growth and prolonged survival when compared with standard ILP alone. However, local disease control could only be secured when such treatment was combined with surgical resection, the timing of which was crucial in determining outcome. Combinations of oncolytic virotherapy with surgical resection and radiation have direct clinical relevance in extremity sarcoma and represent an exciting prospect for improving outcomes in this pathology., What's new? The management of locally advanced or recurrent extremity sarcoma often necessitates multimodal therapy to preserve a limb, of which isolated limb perfusion (ILP) is a key component. But the response to standard ILP is short‐lived in the majority of cases, making novel agents or treatment combinations urgently needed. Previous work in an animal model has demonstrated the effectiveness of combining oncolytic virotherapy with ILP. However, local disease progression was delayed rather than prevented. This paper demonstrates that durable local disease control can be achieved when ILP‐delivered oncolytic virotherapy is utilised as an induction therapy prior to surgical resection and radiotherapy.

Locally advanced head and neck cancer carries a poor prognosis, even with standard combination (surgery, radiotherapy, chemotherapy) treatment regimens. There is a pressing need for novel therapies with activity against this tumour type. Oncolytic reovirus type 3 (Dearing) is preferentially cytotoxic in tumour cells with an activated Ras signalling pathway and represents a promising novel therapy with relevance in head and neck cancer.In this review, we discuss the pre-clinical and clinical data that have underpinned the translational development of oncolytic reovirus thus far. In particular, we describe the iterative nature of the research programme through initial studies testing single-agent reovirus therapy and on to subsequent work in which reovirus has been combined with either radiotherapy or cytotoxic chemotherapy. We will trace the process by which oncolytic reovirus has reached Phase III evaluation in combination with carboplatin/paclitaxel in patients with platin-refractory, relapsed/metastatic head and neck cancer.Reovirus is a self-amplifying, cancer-selective agent that offers huge potential advantages over standard chemotherapy, targeted small molecules or monoclonal antibodies. However, it is most likely that reovirus will show efficacy and be approved in combination with standard modalities (cytotoxic chemotherapy or radiotherapy) or other targeted agents, especially those that modulate signal transduction pathways. The next 5 years are critical for the development of oncolytic reovirus as an anti-cancer therapy and hinge on the ongoing Phase III trial in head and neck cancer and other Phase II programmes.

Reovirus, a replication competent RNA virus, has preclinical activity against melanoma lines and xenografts. We conducted a phase II trial of reovirus in metastatic melanoma patients. Patients received 3 × 10(10) TCID50 on days 1-5 of each 28 day cycle, administered intravenously. Twenty-one eligible patients were enrolled. Treatment was well tolerated without any dose reductions having to be implemented. Post-treatment biopsy samples were obtained in 15 patients, 13/15 contained adequate tumor for correlative analysis. In two patients, productive reoviral replication (viral antigen coexpression with tubulin) was demonstrated, despite increase in neutralizing antibody titers. There were no objective responses although 75-90% tumor necrosis, consistent with treatment effect, was observed in one patient who had metastatic lesions surgically removed. Median time to progression and survival were 45 days (range 13-96 days) and 165 days (range 15 days-15.8 months) respectively. In conclusion, reovirus treatment was well tolerated in metastatic melanoma patients; viral replication was demonstrated in biopsy samples. Based on preclinical data showing synergy with taxane and platinum compounds, a phase II combination trial in metastatic melanoma patients is ongoing.

Oncolytic reovirus is currently under active investigation in a range of tumour types. Early phase studies have shown that this agent has modest monotherapy efficacy and its future development is likely to focus on combination regimens with cytotoxic chemotherapy. Indeed, phase I/II clinical trials have confirmed that reovirus can be safely combined with cytotoxic drugs, including a platin—taxane doublet regimen, which is currently being tested in a phase III clinical trial in patients with relapsed/metastatic head and neck cancer. Therefore, we have tested this triple (reovirus, cisplatin, paclitaxel) combination therapy in a panel of four head and neck cancer cell lines. Using the combination index (CI) method, the triple therapy demonstrated synergistic cytotoxicity in vitro in both malignant and non-malignant cell lines. In head and neck cancer cell lines, this was associated with enhanced caspase 3 and 7 cleavage, but no increase in viral replication. In vitro analyses confirmed colocalisation of markers of reovirus infection and caspase 3. Triple therapy was significantly more effective than reovirus or cisplatin—paclitaxel in athymic nude mice. These data suggest that the combination of reovirus plus platin—taxane doublet chemotherapy has significant activity in head and neck cancer and underpin the current phase III study in this indication.

Purpose: Reovirus type 3 Dearing (RT3D) replicates preferentially in Ras-activated cancers. RT3D shows synergistic in vitro cytotoxicity in combination with platins and taxanes. The purpose of this phase I/II study was to assess RT3D combined with carboplatin/paclitaxel in patients with advanced cancers. Experimental Design: Patients were initially treated in a dose-escalating, phase I trial with intravenous RT3D days 1 to 5, carboplatin [area under curve (AUC) 5, day 1] and paclitaxel (175 mg/m2, day 1) 3-weekly. RT3D was escalated through three dose levels: 3 × 109, 1 × 1010, and 3 × 1010 TCID50 in cohorts of three. Primary endpoints were to define the maximum tolerated dose and dose-limiting toxicity and to recommend a dose for phase II studies. Secondary endpoints included pharmacokinetics, immune response, and antitumor activity. A subsequent phase II study using the 3 × 1010 TCID50 dose characterized the response rate in patients with head and neck cancer. Results: Thirty-one heavily pretreated patients received study therapy. There were no dose-limiting toxicities during dose-escalation and most toxicities were grade I/II. Overall effectiveness rates were as follows: one patient had a complete response (3.8%), six patients (23.1%) had partial response, two patients (7.6%) had major clinical responses clinically evaluated in radiation pretreated lesions which are not evaluable by Response Evaluation Criteria in Solid Tumors (RECIST), nine patients (34.6%) had stable disease, and eight patients (30.8%) had disease progression. Viral shedding was minimal and antiviral immune responses were attenuated compared with previous single-agent data for RT3D. Conclusions: The combination of RT3D plus carboplatin/paclitaxel is well tolerated with evidence of activity in cancer of the head and neck. A randomized phase III study is currently open for recruitment. Clin Cancer Res; 18(7); 2080–9. ©2012 AACR.

Purpose: REOLYSIN (Oncolytics Biotech) consists of a wild-type oncolytic reovirus, which has selective cytotoxicity for tumor cells while sparing normal cells. In a phase I study as a single agent, repeated infusions of reovirus were safe with evidence of antitumor activity. Preclinical studies indicate potential for synergy between reovirus and chemotherapeutic agents. A multicenter, phase I dose escalation study was designed to assess the safety of combining reovirus with docetaxel chemotherapy in patients with advanced cancer. Experimental Design: Patients received 75 mg/m2 docetaxel (day 1) and escalating doses of reovirus up to 3 × 1010 TCID50 (days 1-5) every 3 weeks. Results: Twenty-five patients were enrolled, and 24 patients were exposed to treatment, with 23 completing at least one cycle and 16 suitable for response assessment. Dose-limiting toxicity of grade 4 neutropenia was seen in one patient, but the maximum tolerated dose was not reached. Antitumor activity was seen with one complete response and three partial responses. A disease control rate (combined complete response, partial response, and stable disease) of 88% was observed. Immunohistochemical analysis of reovirus protein expression was observed in posttreatment tumor biopsies from three patients. Conclusion: The combination of reovirus and docetaxel is safe, with evidence of objective disease response, and warrants further evaluation in a phase II study at a recommended schedule of docetaxel (75 mg/m2, three times weekly) and reovirus (3 × 1010 TCID50, days 1-5, every 3 weeks). Clin Cancer Res; 16(22); 5564–72. ©2010 AACR.

Late Adverse Effects (LAEs) following adjuvant radiotherapy (RT) are common sequelae in free flaps used for breast reconstruction and result in ongoing healthcare burdens during the phase of cancer survivorship. Intra-arterial delivery of gene therapy to an isolated vascular region permits localized, targeted genetic modulation of reconstructed tissue, avoiding potential off-target effects in microscopic residual disease. We studied the immunological component of LAE development in a validated accelerated rodent model recapitulating autologous flap reconstruction, across 90 days after RT (50 Gy/3). CXCL12 was significantly up-regulated from 2-21 days after RT, peaking at 7 days (p We hypothesized that LAEs in animals with flap-targeted knockdown of CXCL12 would be reduced. Flaps were infected with vascularly-delivered, lentiviral particles encoding shRNA against CXCL12 (LVshCXCL12), scrambled controls (LVSCR) alongside sham (phosphate-buffered saline (PBS)) and un-irradiated controls. Flaps infected with LVshCXCL12 exhibited reversal of LAE-mediated flap contracture and were not significantly different from un-irradiated flaps at 90 days post-RT, but were significantly greater in area compared to sham flaps or those infected with LVSCR (p In conclusion, targeted knockdown of CXCL12 is effective at preventing the development of LAEs in flap tissue exposed to RT and is a promising strategy for clinical translation. Citation Format: James T. Paget, Martin McLaughlin, Joan N. Kyula, David Mansfield, Henry G. Smith, Victoria Roulstone, Paul A. Harris, Alan A. Melcher, Kevin J. Harrington, Aadil A. Khan. Lentivirally delivered shRNA knockdown of CXCL12 is effective at preventing radiation fibrosis in normal tissues [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4162.

Introduction Systemic relapse is the major cause of mortality in extremity soft tissue sarcoma (ESTS). Traditional systemic therapies for metastatic sarcoma have limited efficacy, as do novel agents such as immune checkpoint inhibitors (ICI). Oncolytic virotherapy is capable of improving the efficacy of ICI in some non-sarcomatous pathology. In a rat model of ESTS, we have previously found isolated limb perfusion (ILP) to be ideally suited to delivering a vaccinia virus (GLV-1h68), alongside melphalan and tumour necrosis factor-α (TNFα). Using this model, we sought to investigate the effects of GLV-1h68 delivered by ILP on the tumour microenvironment and determine whether viral ILP can sensitise sarcomas to subsequent immune checkpoint blockade. Material and methods In vivo experiments were performed in Brown Norway rats bearing BN175 sarcoma in accordance with a Home Office animal license. Therapeutics included GLV-1h68, a PD-1 inhibitor (J43), melphalan and TNFα. Results and discussions PD-1 inhibition had limited in vivo monotherapy efficacy in BN175 sarcoma. Pre-treatment with GLV-1h68 delivered by ILP prior to PD-1 blockade markedly improved therapy, with complete tumour regression in a third of animals. Without further treatment, resistant disease rapidly evolved leading to both local and distant relapse. However, when performed as a neoadjuvant treatment prior to surgery and radiotherapy, viral ILP and PD-1 blockade prevented local and distant relapse in all animals. Treatment with both GLV-1h68 and PD-1 blockade were found to be necessary for durable cure. In vitro , GLV-1h68 induced ATP, calreticulin and HMGB1, markers of immunogenic cell death. In vivo , viral ILP and PD-1 blockade significantly increased the number of intra-tumoural CD4 + and CD8 + effector cells, with an increased proportion of these cells expressing activation markers. Viral ILP and PD-1 blockade also altered the topography of intra-tumoural immune invasion; significantly increasing CD8 + cells within the tumour parenchyma relative to the invasive margin. The accumulation of effector cells within regional lymph nodes, located outside of the perfusion field, was also noted indicative of at least a locoregional, and perhaps, systemic immune-priming. Conclusion Viral ILP and PD-1 blockade combine to prevent local and distant relapse in an animal model of high-grade ESTS. These data provide a strong rationale for clinical translation of this neoadjuvant combination immunotherapy.

Purpose: To determine the safety and feasibility of combining intratumoral reovirus and radiotherapy in patients with advanced cancer and to assess viral biodistribution, reoviral replication in tumors, and antiviral immune responses. Experimental Design: Patients with measurable disease amenable to palliative radiotherapy were enrolled. In the first stage, patients received radiotherapy (20 Gy in five fractions) plus two intratumoral injections of RT3D at doses between 1 × 108 and 1 × 1010 TCID50. In the second stage, the radiotherapy dose was increased (36 Gy in 12 fractions) and patients received two, four, or six doses of RT3D at 1 × 1010 TCID50. End points were safety, viral replication, immunogenicity, and antitumoral activity. Results: Twenty-three patients with various solid tumors were treated. Dose-limiting toxicity was not seen. The most common toxicities were grade 2 (or lower) pyrexia, influenza-like symptoms, vomiting, asymptomatic lymphopenia, and neutropenia. There was no exacerbation of the acute radiation reaction. Reverse transcription-PCR (RT-PCR) studies of blood, urine, stool, and sputum were negative for viral shedding. In the low-dose (20 Gy in five fractions) radiation group, two of seven evaluable patients had a partial response and five had stable disease. In the high-dose (36 Gy in 12 fractions) radiation group, five of seven evaluable patients had partial response and two stable disease. Conclusions: The combination of intratumoral RT3D and radiotherapy was well tolerated. The favorable toxicity profile and lack of vector shedding means that this combination should be evaluated in newly diagnosed patients receiving radiotherapy with curative intent. Clin Cancer Res; 16(11); 3067–77. ©2010 AACR.

Purpose: Reovirus is a wild-type oncolytic virus that is ubiquitous in the environment; most patients are therefore preimmune. Therapeutic administration leads to an increase in neutralizing antireovirus antibody (NARA) titer. We hypothesized that if NARA limited reovirus antitumor activity, the effect might be attenuated by coadministration of cyclophosphamide. Experimental design: In a phase I study, patients with advanced cancer received cyclophosphamide 3 days before intravenous reovirus serotype 3 Dearing (RT3D). The primary objective was to reduce the resulting rise in NARA titer. Cyclophosphamide dose was escalated from 25–1,000 mg/m2 through nine cohorts; we aimed to define a well-tolerated immunomodulatory dose. Results: The combination was well tolerated in 36 patients, with grade 3/4 toxicities only seen at or above the maximum tolerated dose of cyclophosphamide, which was 800 mg/m2 combined with reovirus. Immunosuppressive effect, defined as maintaining NARA titer rise below a predefined threshold, was observed in only one patient. Furthermore, despite expected myelosuppression seen at higher cyclophosphamide doses, no changes in T-cell subsets, including Tregs, occurred with dose escalation. Viable virus was detected in association with peripheral blood mononuclear cells (PBMC) from 14% of patients 10 days after the last RT3D injection, despite high plasma NARA titer, demonstrating a potential mechanism for prolonged evasion of neutralization by reovirus. Conclusions: Coadministration of cyclophosphamide with reovirus is safe, but does not attenuate host antiviral responses. Alternative immunomodulation approaches should be explored, but association with PBMCs may allow reovirus to persist and evade even high levels of neutralizing antibodies. Clin Cancer Res; 21(6); 1305–12. ©2014 AACR.

Purpose: This study combined systemic administration of the oncolytic reovirus type 3 Dearing (reovirus) with chemotherapy in human subjects. We aimed to determine the safety and feasibility of combining reovirus administration with gemcitabine and to describe the effects of gemcitabine on the antireoviral immune response. Experimental Design: Patients received reovirus in various doses, initially we dosed for five consecutive days but this was poorly tolerated. We amended the protocol to administer a single dose and administered up to 3 × 1010 TCID50. Toxicity was assessed by monitoring of clinical and laboratory measurements. We assessed antibody response by cytotoxicity neutralization assay. Results: Sixteen patients received 47 cycles of reovirus. The two initial patients and one patient in the final cohort experienced dose limiting toxicity (DLT). The DLTs consisted of two asymptomatic grade 3 liver enzyme rises and one asymptomatic grade 3 troponin I rise. Common toxicities consisted of known reovirus and gemcitabine associated side effects. Further analysis showed a potential interaction between reovirus and gemcitabine in causing liver enzyme rises. Grade 3 rises in liver enzymes were associated with concomitant aminocetophen use. Importantly, the duration of the liver enzyme rise was short and reversible. Neutralizing antibody responses to reovirus were attenuated both in time-to-occurrence and peak height of the response. Conclusions: Reovirus at the dose of 1 × 1010 TCID50 can be safely combined with full dose gemcitabine. Combination of reovirus with gemcitabine affects the neutralizing antibody response and this could impact both safety and efficacy of this treatment schedule. Clin Cancer Res; 17(3); 581–8. ©2010 AACR.

We have previously demonstrated the antitumour activity of a treatment combining a replication-defective adenovirus encoding the sodium iodide symporter (NIS), external beam radiotherapy (EBRT) and DNA repair inhibitors. Engineered Measles viruses (MeV) expressing NIS are replication-competent, oncolytic viruses, currently being tested in phase 1 trials. The aim of this study was to evaluate the therapeutic efficacy of a combination of MeV-NIS, EBRT, and a novel checkpoint-1 inhibitor, SAR-020106. This approach was investigated in HN-3, HN-5 and PJ-41 head and neck cancer models. In vitro toxicity was assessed by MTS and clonogenic assays. CD46 (cell receptor for MeV) expression on head and neck cell lines was evaluated by flow cytometry. NIS viral transgene expression was assessed by 125I uptake assays. Apoptosis was evaluated by Caspase Glo® and western blot assays. In vivo therapy experiments were performed in CD1 nude mice with subcutaneous tumour xenografts. In this study, we have demonstrated that EBRT and MeV-NIS had in vitro synergistic antitumour effects in head and neck cancer cell lines. EBRT did increase neither CD46 expression nor viral replication, but significantly increased viral gene expression in infected cells. In vitro, SAR-020106 had synergistic antitumour effect with EBRT. This effect was related to increased apoptosis. In vitro, the combination of MeV-NIS and SAR-020106 was associated with a significantly increased antitumour effect, as compared with control, MeV-NIS alone or SAR-020106 alone (P Disclosure All authors have declared no conflicts of interest.