Carcinoembryonic antigen-expressing oncolytic measles virus derivative in recurrent glioblastoma: a phase 1 trial

Measles virus (MV) vaccine strains have shown significant preclinical antitumor activity against glioblastoma (GBM), the most lethal glioma histology. In this first in human trial (NCT00390299), a carcinoembryonic antigen-expressing oncolytic measles virus derivative (MV-CEA), was administered in recurrent GBM patients either at the resection cavity (Group A), or, intratumorally on day 1, followed by a second dose administered in the resection cavity after tumor resection on day 5 (Group B). A total of 22 patients received study treatment, 9 in Group A and 13 in Group B. Primary endpoint was safety and toxicity: treatment was well tolerated with no dose-limiting toxicity being observed up to the maximum feasible dose (2×107 TCID50). Median OS, a secondary endpoint, was 11.6 mo and one year survival was 45.5% comparing favorably with contemporary controls. Other secondary endpoints included assessment of viremia, MV replication and shedding, humoral and cellular immune response to the injected virus. A 22 interferon stimulated gene (ISG) diagonal linear discriminate analysis (DLDA) classification algorithm in a post-hoc analysis was found to be inversely (R = -0.6, p = 0.04) correlated with viral replication and tumor microenvironment remodeling including proinflammatory changes and CD8 + T cell infiltration in post treatment samples. This data supports that oncolytic MV derivatives warrant further clinical investigation and that an ISG-based DLDA algorithm can provide the basis for treatment personalization.

A phase I oncolytic virus trial with vesicular stomatitis virus expressing human interferon beta and tyrosinase related protein 1 administered intratumorally and intravenously in uveal melanoma: safety, efficacy, and T cell responses

Introduction

Metastatic uveal melanoma (MUM) has a poor prognosis and treatment options are limited. These patients do not typically experience durable responses to immune checkpoint inhibitors (ICIs). Oncolytic viruses (OV) represent a novel approach to immunotherapy for patients with MUM.

Methods

We developed an OV with a Vesicular Stomatitis Virus (VSV) vector modified to express interferon-beta (IFN-β) and Tyrosinase Related Protein 1 (TYRP1) (VSV-IFNβ-TYRP1), and conducted a Phase 1 clinical trial with a 3 + 3 design in patients with MUM. VSV-IFNβ-TYRP1 was injected into a liver metastasis, then administered on the same day as a single intravenous (IV) infusion. The primary objective was safety. Efficacy was a secondary objective.

Results

12 patients with previously treated MUM were enrolled. Median follow up was 19.1 months. 4 dose levels (DLs) were evaluated. One patient at DL4 experienced dose limiting toxicities (DLTs), including decreased platelet count (grade 3), increased aspartate aminotransferase (AST), and cytokine release syndrome (CRS). 4 patients had stable disease (SD) and 8 patients had progressive disease (PD). Interferon gamma (IFNγ) ELIspot data showed that more patients developed a T cell response to virus encoded TYRP1 at higher DLs, and a subset of patients also had a response to other melanoma antigens, including gp100, suggesting epitope spreading. 3 of the patients who responded to additional melanoma antigens were next treated with ICIs, and 2 of these patients experienced durable responses.

Discussion

Our study found that VSV-IFNβ -TYRP1 can be safely administered via intratumoral (IT) and IV routes in a previously treated population of patients with MUM. Although there were no clear objective radiographic responses to VSV-IFNβ-TYRP1, dose-dependent immunogenicity to TYRP1 and other melanoma antigens was seen.

Preclinical safety assessment of MV-s-NAP, a novel oncolytic measles virus strain armed with an H . pylori immunostimulatory bacterial transgene

Despite recent therapeutic advances, metastatic breast cancer (MBC) remains incurable. Engineered measles virus (MV) constructs based on the attenuated MV Edmonston vaccine platform have demonstrated significant oncolytic activity against solid tumors. The Helicobacter pylori neutrophil-activating protein (NAP) is responsible for the robust inflammatory reaction in gastroduodenal mucosa during bacterial infection. NAP attracts and activates immune cells at the site of infection, inducing expression of pro-inflammatory mediators. We engineered an MV strain to express the secretory form of NAP (MV-s-NAP) and showed that it exhibits anti-tumor and immunostimulatory activity in human breast cancer xenograft models. In this study, we utilized a measles-infection-permissive mouse model (transgenic IFNAR KO-CD46Ge) to evaluate the biodistribution and safety of MV-s-NAP. The primary objective was to identify potential toxic side effects and confirm the safety of the proposed clinical doses of MV-s-NAP prior to a phase I clinical trial of intratumoral administration of MV-s-NAP in patients with MBC. Both subcutaneous delivery (corresponding to the clinical trial intratumoral administration route) and intravenous (worst case scenario) delivery of MV-s-NAP were well tolerated: no significant clinical, laboratory or histologic toxicity was observed. This outcome supports the safety of MV-s-NAP for oncolytic virotherapy of MBC. The first-in-human clinical trial of MV-s-NAP in patients with MBC (ClinicalTrials.gov: NCT04521764) was subsequently activated.

Live Attenuated Measles Virus Vaccine Expressing Helicobacter pylori Heat Shock Protein A

Measles virus (MV) Edmonston derivative strains are attractive vector platforms in vaccine development and oncolytic virotherapy. Helicobacter pylori heat shock protein A (HspA) is a bacterial heat shock chaperone with essential function as a Ni-ion scavenging protein. We generated and characterized the immunogenicity of an attenuated MV strain encoding the HspA transgene (MV-HspA). MV-HspA showed faster replication within 48 h of infection with >10-fold higher titers and faster accumulation of the MV proteins. It also demonstrated a superior tumor-killing effect in vitro against a variety of human solid tumor cell lines, including sarcoma, ovarian and breast cancer. Two intraperitoneal (i.p.) doses of 10⁶ 50% tissue culture infectious dose (TCID₅₀) MV-HspA significantly improved survival in an ovarian cancer xenograft model: 63.5 days versus 27 days for the control group. The HspA transgene induced a humoral immune response in measles-permissive Ifnarko-CD46Ge transgenic mice. Eight of nine animals developed a long-term anti-HspA antibody response with titers of 1:400 to 1:12,800 without any negative impact on development of protective anti-MV immune memory. MV-HspA triggered an immunogenic cytopathic effect as measured by an HMGB1 assay. The absence of significant elevation of PD-L1 expression indicated that vector-encoded HspA could act as an immunomodulator on the immune check point axis. These data demonstrate that MV-HspA is a potent oncolytic agent and vaccine candidate for clinical translation in cancer treatment and immunoprophylaxis against H. pylori.

Oncolytic Measles Virotherapy and Opposition to Measles Vaccination

Recent measles epidemics in US and European cities where vaccination coverage has declined are providing a harsh reminder for the need to maintain protective levels of immunity across the entire population. Vaccine uptake rates have been declining in large part because of public misinformation regarding a possible association between measles vaccination and autism for which there is no scientific basis. The purpose of this article is to address a new misinformed antivaccination argument-that measles immunity is undesirable because measles virus is protective against cancer. Having worked for many years to develop engineered measles viruses as anticancer therapies, we have concluded (1) that measles is not protective against cancer and (2) that its potential utility as a cancer therapy will be enhanced, not diminished, by prior vaccination.

Mutations in Both the Surface and Transmembrane Envelope Glycoproteins of the RAV-2 Subgroup B Avian Sarcoma and Leukosis Virus Are Required to Escape the Antiviral Effect of a Secreted Form of the TvbS3 Receptor †

The subgroup A through E avian sarcoma and leukosis viruses ASLV(A) through ASLV(E) are a group of highly related alpharetroviruses that have evolved to use very different host protein families as receptors. We have exploited genetic selection strategies to force the replication-competent ASLVs to naturally evolve and acquire mutations to escape the pressure on virus entry and yield a functional replicating virus. In this study, evolutionary pressure was exerted on ASLV(B) virus entry and replication using a secreted for of its Tvb receptor. As expected, mutations in the ASLV(B) surface glycoprotein hypervariable regions were selected that knocked out the ability for the mutant glycoprotein to bind the sTvb^S3-IgG inhibitor. However, the subgroup B Rous associated virus 2 (RAV-2) also required additional mutations in the C-terminal end of the SU glycoprotein and multiple regions of TM highlighting the importance of the entire viral envelope glycoprotein trimer structure to mediate the entry process efficiently. These mutations altered the normal two-step ASLV membrane fusion process to enable infection.

Clinical Trials with Oncolytic Measles Virus: Current Status and Future Prospects

Attenuated Edmonston lineage measles virus (MV-Edm) vaccine strains can preferentially infect and lyse a wide variety of cancer cells. Oncolytic MV-Edm derivatives are genetically engineered to express the human carcinoembryonic antigen (MV-CEA virus) or the human sodium iodide symporter (MV-NIS virus) and are currently being tested in clinical trials against ovarian cancer, glioblastoma multiforme, multiple myeloma, mesothelioma, head and neck cancer, breast cancer and malignant peripheral nerve sheath tumors. This review describes the basic and preclinical data that facilitated the clinical translation of MV-Edm strains, and summarizes the clinical results of this oncolytic platform to date. Furthermore, we discuss the latest clinically relevant MV-Edm vector developments and creative strategies for future translational steps.

Abstract P6-21-03: Phase I trial of intratumoral (IT) administration of a NIS-expressing derivative manufactured from a genetically engineered strain of measles virus (MV)

Background: The live attenuated non-pathogenic Edmonston MV vaccine strain has advantages as an oncolytic platform given its tumor specificity, potent bystander effect, and ability to be engineered and retargeted. MV-NIS expresses the human thyroidal sodium-iodide symporter (NIS) and is selectively oncolytic, entering tumor cells through CD46 (overexpressed on many cancers, including breast cancer of all subtypes) and Nectin-4. NIS expression in MV-NIS infected cells permits noninvasive monitoring of virus spread by SPECT-CT imaging of Tc-99m pertechnetate or I-123 uptake.

Methods: NCT01846091 is a standard 3+3 phase I trial of a single IT administration of MV-NIS in pts with recurrent/metastatic squamous cell carcinoma of the head and neck (SCCHN) or metastatic breast cancer (MBC). Primary objectives are (a) safety and tolerability and (b) maximally tolerated single dose. The secondary clinical objective is to preliminarily assess antitumor efficacy at and away from the MV injection site. Key eligibility criteria were: absence of standard therapy with life prolonging intent; at least one lesion >1 cm amenable to percutaneous injection; and no impending visceral crisis. MV-NIS was administered on D1 with mandatory SPECT-CT at baseline (BL) and on D3&D8; repeat SPECT-CT on D15&D21 if the prior result was positive; mandatory tumor biopsies on D3&D21; optional tumor biopsies on D8&D15; assessments for viremia and viral shedding at BL and on D3,D8,D15,D21; and standard imaging for restaging at BL,D21,W6,W12.

Results: Accrual completed with 12 evaluable pts (6 SCCHN and 6 MBC) at 3 dose levels (108, 3x108, 109 TCID50). The MBC group included 5 HR+/HER2- pts and 1 pt with mixed HR+/HER2- and HR+/HER2+ disease. 5 pts had evidence of disease progression prior to study participation. No dose limiting toxicities were observed among the MBC pts; AEs possibly related to MV-NIS in this group were gr2 fatigue, gr1 flu-like illness, gr2 lymphopenia (all n=1). No SCCHN responses were observed. Best response for the MBC pts was: stable disease (SD) >6 wks, n=4; clinical response, n=1; progression, n=1. One MBC pt with SD for 12 wks had positive SPECT/CT imaging at and away from the injection site on D3&D8 and was the only pt seronegative for measles IgG antibodies prior to MV-NIS exposure. The MBC pt who responded after initial MV-NIS exposure was the only pt with low viral RNA in blood (D3); she received additional doses at W9&W13 without toxicity through an expanded access protocol exemption and had disease progression by W19. No viral shedding was detected from mouth rinse or urine in any pt. MV was detected in tumor samples from all pts treated at the highest dose level. Additional blood and tissue analyses are in progress.

Conclusion: These results demonstrate the safety of IT MV-NIS administration, provide early evidence of biologic activity in MBC, and support the possibility of viral replication in tumors remote from the IT injection site. A MV strain encoding the immunomodulatory neutrophil activating protein transgene has been constructed (MV-s-NAP) with preclinical evidence of improved antitumor activity and immunogenicity. The phase I MV-s-NAP trial will start recruitment in Fall 2018.

Citation Format: Liu MC, Peng K-W, Federspiel MJ, Russell SJ, Brunton BA, Zhou Y, Packiriswamy N, Hubbard JM, Loprinzi CL, Peethambaram PP, Ruddy KJ, Allred JB, Galanis E, Okuno SH. Phase I trial of intratumoral (IT) administration of a NIS-expressing derivative manufactured from a genetically engineered strain of measles virus (MV) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-21-03.

Comparative Oncology Evaluation of Intravenous Recombinant Oncolytic Vesicular Stomatitis Virus Therapy in Spontaneous Canine Cancer

Clinical translation of intravenous therapies to treat disseminated or metastatic cancer is imperative. Comparative oncology, the evaluation of novel cancer therapies in animals with spontaneous cancer, can be utilized to inform and accelerate clinical translation. Preclinical murine studies demonstrate that single-shot systemic therapy with a vesicular stomatitis virus (VSV)-IFNβ-NIS, a novel recombinant oncolytic VSV, can induce curative remission in tumor-bearing mice. Clinical translation of VSV-IFNβ-NIS therapy is dependent on comprehensive assessment of clinical toxicities, virus shedding, pharmacokinetics, and efficacy in clinically relevant models. Dogs spontaneously develop cancer with comparable etiology, clinical progression, and response to therapy as human malignancies. A comparative oncology study was carried out to investigate feasibility and tolerability of intravenous oncolytic VSV-IFNβ-NIS therapy in pet dogs with spontaneous cancer. Nine dogs with various malignancies were treated with a single intravenous dose of VSV-IFNβ-NIS. Two dogs with high-grade peripheral T-cell lymphoma had rapid but transient remission of disseminated disease and transient hepatotoxicity that resolved spontaneously. There was no shedding of infectious virus. Correlative pharmacokinetic studies revealed elevated levels of VSV RNA in blood in dogs with measurable disease remission. This is the first evaluation of intravenous oncolytic virus therapy for spontaneous canine cancer, demonstrating that VSV-IFNβ-NIS is well-tolerated and safe in dogs with advanced or metastatic disease. This approach has informed clinical translation, including dose and target indication selection, leading to a clinical investigation of intravenous VSV-IFNβ-NIS therapy, and provided preliminary evidence of clinical efficacy and potential biomarkers that correlate with therapeutic response. Mol Cancer Ther; 17(1); 316-26. ©2017 AACR.

Safety Studies in Tumor and Non-Tumor-Bearing Mice in Support of Clinical Trials Using Oncolytic VSV-IFNβ-NIS

Oncolytic VSV-IFNβ-NIS is selectively destructive to tumors. Here, we present the IND enabling preclinical rodent studies in support of clinical testing of vesicular stomatitis virus (VSV) as a systemic therapy. Efficacy studies showed dose-dependent tumor regression in C57BL/KaLwRij mice bearing syngeneic 5TGM1 plasmacytomas after systemic VSV administration. In contrast, the virus was effective at all doses tested against human KAS6/1 xenografts in SCID mice. Intravenous administration of VSV-mIFNβ-NIS is well tolerated in C57BL/6 mice up to 5 × 10(10) TCID50 (50% tissue culture infective dose)/kg with no neurovirulence, no cytokine storm, and no abnormalities in tissues. Dose-limiting toxicities included elevated transaminases, thrombocytopenia, and lymphopenia. Inactivated viral particles did not cause hepatic toxicity. Intravenously administered VSV was preferentially sequestered by macrophages in the spleen and liver. Quantitative RT-PCR analysis for total viral RNA on days 2, 7, 21, and 58 showed highest VSV RNA in day 2 samples; highest in spleen, liver, lung, lymph node, kidney, gonad, and bone marrow. No infectious virus was recovered from tissues at any time point. The no observable adverse event level and maximum tolerated dose of VSV-mIFNβ-NIS in C57BL/6 mice are 10(10) TCID50/kg and 5 × 10(10) TCID50/kg, respectively. Clinical translation of VSV-IFNβ-NIS is underway in companion dogs with cancer and in human patients with relapsed hematological malignancies and endometrial cancer.

Vesicular stomatitis virus expressing interferon-β is oncolytic and promotes antitumor immune responses in a syngeneic murine model of non-small cell lung cancer

Vesicular stomatitis virus (VSV) is a potent oncolytic virus for many tumors. VSV that produces interferon-β (VSV-IFNβ) is now in early clinical testing for solid tumors. Here, the preclinical activity of VSV and VSV-IFNβ against non-small cell lung cancer (NSCLC) is reported. NSCLC cell lines were treated in vitro with VSV expressing green fluorescence protein (VSV-GFP) and VSV-IFNβ. VSV-GFP and VSV-IFNβ were active against NSCLC cells. JAK/STAT inhibition with ruxolitinib re-sensitized resistant H838 cells to VSV-IFNβ mediated oncolysis. Intratumoral injections of VSV-GFP and VSV-IFNβ reduced tumor growth and weight in H2009 nude mouse xenografts (p < 0.01). A similar trend was observed in A549 xenografts. Syngeneic LM2 lung tumors grown in flanks of A/J mice were injected with VSV-IFNβ intratumorally. Treatment of LM2 tumors with VSV-IFNβ resulted in tumor regression, prolonged survival (p < 0.0001), and cure of 30% of mice. Intratumoral injection of VSV-IFNβ resulted in decreased tumor-infiltrating regulatory T cells (T_reg) and increased CD8⁺ T cells. Tumor cell expression of PDL-1 was increased after VSV-IFNβ treatment. VSV-IFNβ has potent antitumor effects and promotes systemic antitumor immunity. These data support further clinical investigation of VSV-IFNβ for NSCLC.

Inhibition of the Aurora A kinase augments the anti-tumor efficacy of oncolytic measles virotherapy

Oncolytic measles virus (MV) strains have demonstrated broad spectrum preclinical anti-tumor, including breast cancer. Aurora A kinase controls mitotic spindle formation and plays a critical role in malignant transformation. We hypothesized that, by causing mitotic arrest, the Aurora A kinase inhibitor MLN8237 (alisertib) can increase MV oncolytic effect and efficacy. Alisertib enhanced MV oncolysis in vitro and significantly improved outcome in vivo against breast cancer xenografts. In a disseminated MDA-231-lu-P4 lung metastatic model, the MV/alisertib combination treatment markedly increased median survival to 82.5 days with 20% of the animals being long term survivors vs. 48 days median survival for the control animals. Similarly, in a pleural effusion model of advanced breast cancer, the MV/alisertib combination significantly improved outcome with a 74.5 day median survival versus the single agent groups (57 and 40 days respectively). Increased viral gene expression and IL-24 upregulation were demonstrated, representing possible mechanisms for the observed increase in antitumor effect. Inhibiting Aurora A kinase with alisertib represents a novel approach to enhance measles virus-mediated oncolysis and antitumor effect. Both oncolytic MV strains and alisertib are currently tested in clinical trials, this study therefore provides the basis for translational applications of this combinatorial strategy in the treatment of patients with advanced breast cancer.

Oncolytic measles virus expressing the sodium iodide symporter to treat drug-resistant ovarian cancer

Edmonston vaccine strains of measles virus (MV) have significant antitumor activity in mouse xenograft models of ovarian cancer. MV engineered to express the sodium iodide symporter gene (MV-NIS) facilitates localization of viral gene expression and offers a tool for tumor radiovirotherapy. Here, we report results from a clinical evaluation of MV-NIS in patients with taxol- and platinum-resistant ovarian cancer. MV-NIS was given intraperitoneally every 4 weeks for up to 6 cycles. Treatment was well tolerated and associated with promising median overall survival in these patients with heavily pretreated ovarian cancer; no dose-limiting toxicity was observed in 16 patients treated at high-dose levels (10(8)-10(9) TCID50), and their median overall survival of 26.5 months compared favorably with other contemporary series. MV receptor CD46 and nectin-4 expression was confirmed by immunohistochemistry in patient tumors. Sodium iodide symporter expression in patient tumors after treatment was confirmed in three patients by (123)I uptake on SPECT/CTs and was associated with long progression-free survival. Immune monitoring posttreatment showed an increase in effector T cells recognizing the tumor antigens IGFBP2 and FRα, indicating that MV-NIS treatment triggered cellular immunity against the patients' tumor and suggesting that an immune mechanism mediating the observed antitumor effect. Our findings support further clinical evaluation of MV-NIS as an effective immunovirotherapy.

Safety studies on intravenous administration of oncolytic recombinant vesicular stomatitis virus in purpose-bred beagle dogs

VSV-IFNβ-NIS is a novel recombinant oncolytic vesicular stomatitis virus (VSV) with documented efficacy and safety in preclinical murine models of cancer. To facilitate clinical translation of this promising oncolytic therapy in patients with disseminated cancer, we are utilizing a comparative oncology approach to gather data describing the safety and efficacy of systemic VSV-IFNβ-NIS administration in dogs with naturally occurring cancer. In support of this, we executed a dose-escalation study in purpose-bred dogs to determine the maximum tolerated dose (MTD) of systemic VSV-hIFNβ-NIS, characterize the adverse event profile, and describe routes and duration of viral shedding in healthy, immune-competent dogs. The data indicate that an intravenous dose of 10(10) TCID50 is well tolerated in dogs. Expected adverse events were mild to moderate fever, self-limiting nausea and vomiting, lymphopenia, and oral mucosal lesions. Unexpected adverse events included prolongation of partial thromboplastin time, development of bacterial urinary tract infection, and scrotal dermatitis, and in one dog receiving 10(11) TCID50 (10 × the MTD), the development of severe hepatotoxicity and symptoms of shock leading to euthanasia. Viral shedding data indicate that detectable viral genome in blood diminishes rapidly with anti-VSV neutralizing antibodies detectable in blood as early as day 5 postintravenous virus administration. While low levels of viral genome copies were detectable in plasma, urine, and buccal swabs of dogs treated at the MTD, no infectious virus was detectable in plasma, urine, or buccal swabs at any of the doses tested. These studies confirm that VSV can be safely administered systemically in dogs, justifying the use of oncolytic VSV as a novel therapy for the treatment of canine cancer.

Measles vaccine strains for virotherapy of non-small-cell lung carcinoma

INTRODUCTION

Oncolytic virus therapy is a promising therapy for numerous tumor types. Edmonston-strain measles virus (MV) has been tested in clinical trials for ovarian cancer, glioma, and myeloma. Therefore, the antitumor activity of MV against non-small-cell lung cancer (NSCLC) was assessed.

METHODS

Human NSCLC cells and immortalized lung epithelial cell lines, Beas2B, were infected with either MV-producing green fluorescent protein or MV-producing carcinoembryonic antigen. Cells were assessed for viability, induction of apoptosis by caspase and poly-ADP ribose polymerase cleavage, and for viral transgene production. The dependency of MV entry on CD46 and nectin-4 were determined using blocking antibodies. The role of host translational activity on viral replication was assessed by overexpression of eIF4E and translation inhibition. Antitumor activity was assessed by measuring treated NSCLC xenografts from flanks of nude mice.

RESULTS

MV infection of NSCLC cells results in potent cell killing in most of the cell lines compared with immortalized Beas2B cells and induces apoptosis. MV infection was prevented by blocking of CD46, however independent of nectin-4 blockade. Tumor weights are diminished after intratumoral injections of MV-producing carcinoembryonic antigen in one of two cell lines and result in detectable viral transgene in serum of mice.

CONCLUSIONS

These data indicate that MV is oncolytic for human NSCLC and this was independent of nectin-4 expression. Dysregulated protein translational machinery may play a role in determining tumor tropism in NSCLC. MV combined with gemcitabine could be explored further as chemovirotherapy for NSCLC.

Remission of disseminated cancer after systemic oncolytic virotherapy

MV-NIS is an engineered measles virus that is selectively destructive to myeloma plasma cells and can be monitored by noninvasive radioiodine imaging of NIS gene expression. Two measles-seronegative patients with relapsing drug-refractory myeloma and multiple glucose-avid plasmacytomas were treated by intravenous infusion of 10(11) TCID50 (50% tissue culture infectious dose) infectious units of MV-NIS. Both patients responded to therapy with M protein reduction and resolution of bone marrow plasmacytosis. Further, one patient experienced durable complete remission at all disease sites. Tumor targeting was clearly documented by NIS-mediated radioiodine uptake in virus-infected plasmacytomas. Toxicities resolved within the first week after therapy. Oncolytic viruses offer a promising new modality for the targeted infection and destruction of disseminated cancer.

Preclinical safety and activity of recombinant VSV-IFN-β in an immunocompetent model of squamous cell carcinoma of the head and neck

BACKGROUND

Recombinant vesicular stomatitis virus expressing interferon-β (VSV-IFN-β) has demonstrated antitumor activity in vitro and in vivo. In preparation for clinical testing in human squamous cell carcinoma (SCC) of the head and neck, we conducted preclinical studies of VSV-IFN-β in syngeneic SCC models.

METHODS

In vitro, VSV-IFN-β (expressing rat or mouse interferon [IFN]-β)-induced cytotoxicity and propagated in rat (FAT-7) or mouse (SCC-VII) SCC cells during normoxia and hypoxia. In vivo, intratumoral administration of VSV-rat-IFN-β or VSV-human-IFN-β in FAT-7 bearing or non-tumor bearing immunocompetent rats did not result in acute organ toxicity or death.

RESULTS

VSV-r-IFN-β replicated predominantly in tumors and a dose dependent anti-VSV antibody response was observed. Intratumoral or intravenous administration of VSV-IFN-β resulted in growth delay and improved survival compared with controls.

CONCLUSION

The above data confirm safety and feasibility of VSV-IFN-β administration in immunocompetent animals and support its clinical evaluation in advanced human head and neck cancer.

Oncolytic measles and vesicular stomatitis virotherapy for endometrial cancer

OBJECTIVE

Current adjuvant therapy for advanced-stage, recurrent, and high-risk endometrial cancer (EC) has not reduced mortality from this malignancy, and novel systemic therapies are imperative. Oncolytic viral therapy has been shown to be effective in the treatment of gynecologic cancers, and we investigated the in vitro and in vivo efficacy of the Edmonston strain of measles virus (MV) and vesicular stomatitis virus (VSV) on EC.

METHODS

Human EC cell lines (HEC-1-A, Ishikawa, KLE, RL95-2, AN3 CA, ARK-1, ARK-2, and SPEC-2) were infected with Edmonston strain MV expressing the thyroidal sodium iodide symporter, VSV expressing either human or murine IFN-β, or recombinant VSV with a methionine deletion at residue 51 of the matrix protein and expressing the sodium iodide symporter. Xenografts of HEC-1-A and AN3 CA generated in athymic mice were treated with intratumoral MV or VSV or intravenous VSV.

RESULTS

In vitro, all cell lines were susceptible to infection and cell killing by all 3 VSV strains except KLE. In addition, the majority of EC cell lines were defective in their ability to respond to type I IFN. Intratumoral VSV-treated tumors regressed more rapidly than MV-treated tumors, and intravenous VSV resulted in effective tumor control in 100% of mice. Survival was significantly longer for mice treated with any of the 3 VSV strains compared with saline.

CONCLUSION

VSV is clearly more potent in EC oncolysis than MV. A phase 1 clinical trial of VSV in EC is warranted.

Meningeal myeloma deposits adversely impact the therapeutic index of an oncolytic VSV

Vesicular stomatitis virus (VSV) is neuropathogenic in rodents but can be attenuated 50-fold by engineering the mouse interferon-beta (IFN-β) gene into its genome. Intravenously administered VSVs encoding IFN-β have potent activity against subcutaneous tumors in the 5TGM1 mouse myeloma model, without attendant neurotoxicity. However, when 5TGM1 tumor cells were seeded intravenously, virus-treated mice with advanced myeloma developed clinical signs suggestive of meningoencephalitis. Co-administration of a known active antimyeloma agent did not prolong survival, further suggesting that deaths were due to viral toxicity, not tumor burden. Histological analysis revealed that systemically administered 5TGM1 cells seed to the CNS, forming meningeal tumor deposits, and that VSV infects and destroys these tumors. Death is presumably a consequence of meningeal damage and/or direct transmission of virus to adjacent neural tissue. In light of these studies, extreme caution is warranted in clinical testing of attenuated VSVs, particularly in patients with CNS tumor deposits.

Systemically delivered measles virus-infected mesenchymal stem cells can evade host immunity to inhibit liver cancer growth

BACKGROUND & AIMS

Although attenuated measles virus (MV) has demonstrated potent oncolytic activities towards human cancers, it has not yet been widely adopted into clinical practice. One of the major hurdles is the presence of pre-existing anti-MV immunity in the recipients. In this study, we have evaluated the combination of the potent oncolytic activity of the attenuated MV with the unique immunoprivileged and tumor-tropic biological properties of human bone marrow-derived mesenchymal stem cells (BM-hMSCs) to combat human hepatocellular carcinoma (HCC), orthotopically implanted in SCID mice, passively immunized with human neutralizing antibodies against MV as a preclinical model.

METHODS

SCID mice were orthotopically implanted with patient-derived HCC tissues and established HCC cell lines. SCID mice were passively immunized with human neutralizing anti-measles antibodies. Bioluminescence and fluorescence imaging were employed to monitor the ability of systemically delivered MV-infected BM-hMSCs to infiltrate the implanted tumors and their effects on tumor growth.

RESULTS

Systemically delivered MV-infected BM-hMSCs homed to the HCC tumors implanted orthotopically in the liver and it was evidenced that BM-hMSCs could transfer MV infectivity to HCC via heterofusion. Furthermore, therapy with MV-infected BM-hMSCs resulted in significant inhibition of tumor growth in both measles antibody-naïve and passively-immunized SCID mice. By contrast, when cell-free MV viruses were delivered systemically, antitumor activity was evident only in measles antibody-naïve SCID mice.

CONCLUSIONS

MV-infected BM-hMSCs cell delivery system provides a feasible strategy to elude the presence of immunity against MV in most of the potential cancer patients to be treated with the oncolytic MV viruses.

Mathematical model for radial expansion and conflation of intratumoral infectious centers predicts curative oncolytic virotherapy parameters

Simple, inductive mathematical models of oncolytic virotherapy are needed to guide protocol design and improve treatment outcomes. Analysis of plasmacytomas regressing after a single intravenous dose of oncolytic vesicular stomatitis virus in myeloma animal models revealed that intratumoral virus spread was spatially constrained, occurring almost exclusively through radial expansion of randomly distributed infectious centers. From these experimental observations we developed a simple model to calculate the probability of survival for any cell within a treated tumor. The model predicted that small changes to the density of initially infected cells or to the average maximum radius of infected centers would have a major impact on treatment outcome, and this was confirmed experimentally. The new model provides a useful and flexible tool for virotherapy protocol optimization.

Measles virus expressed Helicobacter pylori neutrophil-activating protein significantly enhances the immunogenicity of poor immunogens

Helicobacter pylori neutrophil-activating protein (NAP) is a toll-like receptor 2 (TLR2) agonist and potent immunomodulator inducing Th1-type immune response. Here we present data about characterization of the humoral immune response against NAP-tagged antigens, encoded by attenuated measles virus (MV) vector platform, in MV infection susceptible type I interferon receptor knockout and human CD46 transgenic (Ifnarko-CD46Ge) mice. Immunogenicity of MV expressing a full-length human immunoglobulin lambda light chain (MV-lambda) was compared to that of MV expressing lambda-NAP chimeric protein (MV-lambda-NAP). MV-lambda-NAP immunized Ifnarko-CD46Ge mice developed significantly higher (6-20-fold) anti-lambda ELISA titers as compared to the MV-lambda-immunized control animal group, indicating that covalently-linked NAP co-expression significantly enhanced lambda immunogenicity. In contrast, ELISA titers against MV antigens were not significantly different between the animals vaccinated with MV-lambda or MV-lambda-NAP. NAP-tagged antigen expression did not affect development of protective anti-measles immunity. Both MV-lambda and MV-lambda-NAP-immunized groups showed strong virus neutralization serum titers in plaque reduction microneutralization test. These results demonstrated that MV-encoded lambda-NAP is highly immunogenic as compared to the unmodified full-length lambda chain. Boost of immune response to poor immunogens using live vectors expressing NAP-tagged chimeric antigens is an attractive approach with potential application in immunoprophylaxis of infectious diseases and cancer immunotherapy.

Optimising measles virus-guided radiovirotherapy with external beam radiotherapy and specific checkpoint kinase 1 inhibition

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.

Optimizing patient derived mesenchymal stem cells as virus carriers for a phase I clinical trial in ovarian cancer

Background

Mesenchymal stem cells (MSC) can serve as carriers to deliver oncolytic measles virus (MV) to ovarian tumors. In preparation for a clinical trial to use MSC as MV carriers, we obtained cells from ovarian cancer patients and evaluated feasibility and safety of this approach.

Methods

MSC from adipose tissues of healthy donors (hMSC) and nine ovarian cancer patients (ovMSC) were characterized for susceptibility to virus infection and tumor homing abilities.

Results

Adipose tissue (range 0.16-3.96 grams) from newly diagnosed and recurrent ovarian cancer patients yielded about 7.41×10⁶ cells at passage 1 (range 4–9 days). Phenotype and doubling times of MSC were similar between ovarian patients and healthy controls. The time to harvest of 3.0×10⁸ cells (clinical dose) could be achieved by day 14 (range, 9–17 days). Two of nine samples tested had an abnormal karyotype represented by trisomy 20. Despite receiving up to 1.6×10⁹ MSC/kg, no tumors were seen in SCID beige mice and MSC did not promote the growth of SKOV3 human ovarian cancer cells in mice. The ovMSC migrated towards primary ovarian cancer samples in chemotaxis assays and to ovarian tumors in athymic mice. Using non-invasive SPECT-CT imaging, we saw rapid co-localization, within 5–8 minutes of intraperitoneal administration of MV infected MSC to the ovarian tumors. Importantly, MSC can be pre-infected with MV, stored in liquid nitrogen and thawed on the day of infusion into mice without loss of activity. MV infected MSC, but not virus alone, significantly prolonged the survival of measles immune ovarian cancer bearing animals.

Conclusions

These studies confirmed the feasibility of using patient derived MSC as carriers for oncolytic MV therapy. We propose an approach where MSC from ovarian cancer patients will be expanded, frozen and validated to ensure compliance with the release criteria. On the treatment day, the cells will be thawed, washed, mixed with virus, briefly centrifuged and incubated for 2 hours with virus prior to infusion of the virus/MSC cocktail into patients.

Neutralization capacity of measles virus H protein specific IgG determines the balance between antibody-enhanced infectivity and protection in microglial cells

Neutralizing antibodies directed against measles virus (MV) surface glycoproteins prevent viral attachment and entry through the natural receptors. H protein specific IgG can enhance MV infectivity in macrophages via Fcγ receptor (FcγR)-dependent mechanism. H-specific IgM, anti-F antibodies and complement cascade activation are protective against antibody-mediated enhancement of MV infection. However, protective role of anti-H IgG against antibody-enhanced infection is not well understood. Here we designed a set of experiments to test the protective effect of H-specific IgG against FcγR-mediated infection in microglial cells. Microglial cells are also potential target of the antibody-mediated enhancement and spread of MV infection in the central nervous system. A partially neutralizing IgG monoclonal antibody (MAb) CL55, specific for MV H protein, at 10 μg/ml enhanced MV infection in mouse microglial cells by 13-14-fold. Infection-enhancing antibody concentrations induced large multinucleated syncytia formation 48-72 h post-inoculation. We generated anti-H IgG MAb 20H6 with a strong neutralization capacity >1:80,000 at 1mg/ml concentration in MV plaque-reduction neutralization assay. In contrast to the partially protective MAb CL55, enhancement of MV infectivity by MAb 20H6 required dilutions below the 1:120 serum titer considered protective against measles infection in humans. At a concentration of 10 μg/ml MAb 20H6 exhibited a dominant protective effect and prevented MAb CL55-mediated enhancement of MV infection and virus-mediated fusion. These results indicate that neutralization capacity of the H-specific IgG determines the balance between antibody enhancement and protection against MV infection in microglial cells.

Progress in gene therapy for prostate cancer

Gene therapy has held promise to correct various disease processes. Prostate cancer represents the second leading cause of cancer death in American men. A number of clinical trials involving gene therapy for the treatment of prostate cancer have been reported. The ability to efficiently transduce tumors with effective levels of therapeutic genes has been identified as a fundamental barrier to effective cancer gene therapy. The approach utilizing gene therapy in prostate cancer patients at our institution attempts to address this deficiency. The sodium-iodide symporter (NIS) is responsible for the ability of the thyroid gland to transport and concentrate iodide. The characteristics of the NIS gene suggest that it could represent an ideal therapeutic gene for cancer therapy. Published results from Mayo Clinic researchers have indicated several important successes with the use of the NIS gene and prostate gene therapy. Studies have demonstrated that transfer of the human NIS gene into prostate cancer using adenovirus vectors in vitro and in vivo results in efficient uptake of radioactive iodine and significant tumor growth delay with prolongation of survival. Preclinical successes have culminated in the opening of a phase I trial for patients with advanced prostate disease which is currently accruing patients. Further study will reveal the clinical promise of NIS gene therapy in the treatment of prostate as well as other malignancies.

Oncolytic measles virus strains have significant antitumor activity against glioma stem cells

Glioblastoma (GBM) is the most common primary brain tumor in adults and has a dismal prognosis despite multimodality treatment. Given the resistance of glioma stem cells (GSC) to chemotherapy and radiation therapy, their eradication could prevent tumor recurrence. We sought to evaluate the antitumor activity of measles virus (MV) derivatives against GSC. We generated neurosphere cultures from patient-derived primary tumor GBM xenografts, and we characterized them for the GSC markers CD133, SOX2, Nestin, ATF5 and OLIG2. Using the MV-strains MV-GFP, MV-CEA and MV-NIS we demonstrated infection, viral replication and significant cytopathic effect in vitro against GSC lines. In tumorigenicity experiments, GBM44 GSC were infected with MV in vitro and subsequently implanted into the right caudate nucleus of nude mice: significant prolongation of survival in mice implanted with infected GSC was observed, compared with mock-infected controls (P=0.0483). In therapy experiments in GBM6 and GBM12 GSC xenograft models, there was significant prolongation of survival in MV-GFP-treated animals compared with inactivated virus-treated controls (GBM6 P=0.0021, GBM12 P=0.0416). Abundant syncytia and viral replication was demonstrated in tumors of MV-treated mice. Measles virus derivatives have significant antitumor activity against glioma-derived stem cells in vitro and in vivo.

Using clinically approved cyclophosphamide regimens to control the humoral immune response to oncolytic viruses

Oncolytic viruses can be neutralized in the bloodstream by antiviral antibodies whose titers increase progressively with each exposure, resulting in faster virus inactivation and further reductions in efficacy with each successive dose. A single dose of cyclophosphamide (CPA) at 370 mg m(-2) was not sufficient to control the primary antiviral immune responses in mice, squirrel monkeys and humans. We therefore tested clinically approved multidose CPA regimens, which are known to kill proliferating lymphocytes, to determine if more intensive CPA therapy can more effectively suppress antiviral antibody responses during virotherapy. In virus-susceptible mice, primary antibody responses to intravenously (i.v.) administered oncolytic measles virus (MV) or vesicular stomatitis virus (VSV) were partially or completely suppressed, respectively, by oral (1 mg × 8 days) or systemic (3 mg × 4 days) CPA regimens initiated 1 day before virus. When MV- or VSV-immune mice were re-challenged with the respective viruses and concurrently treated with four daily systemic doses of CPA, their anamnestic antibody responses were completely suppressed and antiviral antibody titers fell significantly below pre-booster levels. We conclude that the CPA regimen of four daily doses at 370 mg m(-2) should be evaluated clinically with i.v. virotherapy to control the antiviral antibody response and facilitate effective repeat dosing.

Curative one-shot systemic virotherapy in murine myeloma

Current therapy for multiple myeloma is complex and prolonged. Antimyeloma drugs are combined in induction, consolidation and/or maintenance protocols to destroy bulky disease, then suppress or eradicate residual disease. Oncolytic viruses have the potential to mediate both tumor debulking and residual disease elimination, but this curative paradigm remains unproven. Here we engineered an oncolytic vesicular stomatitis virus to minimize its neurotoxicity, enhance induction of antimyeloma immunity, and facilitate noninvasive monitoring of its intratumoral spread. Using high resolution imaging, autoradiography and immunohistochemistry, we demonstrate that the intravenously administered virus extravasates from tumor blood vessels in immunocompetent myeloma-bearing mice, nucleating multiple intratumoral infectious centers which expand rapidly and necrose at their centers, ultimately coalescing to cause extensive tumor destruction. This oncolytic tumor debulking phase lasts only for 72 hours after virus administration, and is completed before antiviral antibodies become detectable in the bloodstream. Anti-myeloma T cells, cross-primed as the virus-infected cells provoke an antiviral immune response, then eliminate residual uninfected myeloma cells. The study establishes a curative oncolytic paradigm for multiple myeloma where direct tumor debulking and immune eradication of minimal disease are mediated by a single intravenous dose of a single therapeutic agent. Clinical translation is underway.

Expression of immunomodulatory neutrophil-activating protein of Helicobacter pylori enhances the antitumor activity of oncolytic measles virus

Helicobacter pylori neutrophil-activating protein (NAP) is a major virulence factor and powerful inducer of inflammatory reaction and Th1-polarized immune response. Here, we evaluated the therapeutic efficacy of measles virus (MV) strains engineered to express secretory NAP forms against metastatic breast cancer. Recombinant viruses encoding secretory NAP forms (MV-lambda-NAP and MV-s-NAP) efficiently infect and destroy breast cancer cells by cell-to-cell viral spread and large syncytia formation independently of hormone receptor status. Intrapleural administration of MV-s-NAP doubled the median survival in a pleural effusion xenograft model: 65 days as compared to 29 days in the control group (P < 0.0001). This therapeutic effect correlated with a brisk Th1 type cytokine response in vivo. Secretory NAP was expressed at high levels by infected tumor cells and increased tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-12/23 cytokine concentrations were detected in the pleural effusion. In an aggressive model of lung metastatic breast cancer, MV-lambda-NAP and MV-s-NAP also significantly improved survival of the treated animals (P < 0.05) as compared to the control MV strain. These data suggest that potent immunomodulators of bacterial origin, such as H. pylori NAP, can enhance the antitumor effect of oncolytic viruses and support the feasibility and potential of a combined viroimmunotherapy approach.

Polyinosinic acid decreases sequestration and improves systemic therapy of measles virus

Off target binding or vector sequestration can significantly limit the efficiency of systemic virotherapy. We report here that systemically administered oncolytic measles virus (MV) was rapidly sequestered by the mononuclear phagocytic system (MPS) of the liver and spleen in measles receptor CD46-positive and CD46-negative mice. Since scavenger receptors on Kupffer cells are responsible for the elimination of blood-borne pathogens, we investigated here if MV uptake was mediated by scavenger receptors on Kupffer cells. Pretreatment of cells with poly(I), a scavenger receptor ligand, reduced MV expression by 99% in murine (J774A.1) macrophages and by 50% in human (THP-1) macrophages. Pre-dosing of mice with poly(I) reduced MPS sequestration of MV and increased circulating levels of MV by 4 to 15-folds at 2 minutes post virus administration. Circulating virus was still detectable 30 mins post infusion in mice predosed with poly(I) while no detectable MV was found at 5–10 min post infusion if mice did not receive poly(I). MPS blockade by poly(I) enhanced virus delivery to human ovarian SKOV3ip.1 and myeloma KAS6/1 xenografts in mice. Higher gene expression and improved control of tumor growth was noted early post therapy. Based on these results, incorporation of MPS blockade into MV treatment regimens is warranted.

Pinhole micro-SPECT/CT for noninvasive monitoring and quantitation of oncolytic virus dispersion and percent infection in solid tumors

The purpose of our study was to validate the ability of pinhole micro-single-photon emission computed tomography/computed tomography (SPECT/CT) to 1) accurately resolve the intratumoral dispersion pattern and 2) quantify the infection percentage in solid tumors of an oncolytic measles virus encoding the human sodium iodide symporter (MV-NIS). NIS RNA level and dispersion pattern were determined in control and MV-NIS infected BxPC-3 pancreatic tumor cells and mouse xenografts using quantitative, real-time, reverse transcriptase, polymerase chain reaction, autoradiography, and immunohistochemistry (IHC). Mice with BxPC-3 xenografts were imaged with ¹²³I or ⁹⁹TcO₄ micro-SPECT/CT. Tumor dimensions and radionuclide localization were determined with imaging software. Linear regression and correlation analyses were performed to determine the relationship between tumor infection percentage and radionuclide uptake (% injected dose per gram) above background and a highly significant correlation was observed (r² = 0.947). A detection threshold of 1.5-fold above the control tumor uptake (background) yielded a sensitivity of 2.7% MV-NIS infected tumor cells. We reliably resolved multiple distinct intratumoral zones of infection from noninfected regions. Pinhole micro-SPECT/CT imaging using the NIS reporter demonstrated precise localization and quantitation of oncolytic MV-NIS infection and can replace more time-consuming and expensive analyses (eg, autoradiography and IHC) that require animal sacrifice.

Simple, automated, high resolution mass spectrometry method to determine the disulfide bond and glycosylation patterns of a complex protein: subgroup A avian sarcoma and leukosis virus envelope glycoprotein

Enveloped viruses must fuse the viral and cellular membranes to enter the cell. Understanding how viral fusion proteins mediate entry will provide valuable information for antiviral intervention to combat associated disease. The avian sarcoma and leukosis virus envelope glycoproteins, trimers composed of surface (SU) and transmembrane heterodimers, break the fusion process into several steps. First, interactions between SU and a cell surface receptor at neutral pH trigger an initial conformational change in the viral glycoprotein trimer followed by exposure to low pH enabling additional conformational changes to complete the fusion of the viral and cellular membranes. Here, we describe the structural characterization of the extracellular region of the subgroup A avian sarcoma and leukosis viruses envelope glycoproteins, SUATM129 produced in chicken DF-1 cells. We developed a simple, automated method for acquiring high resolution mass spectrometry data using electron capture dissociation conditions that preferentially cleave the disulfide bond more readily than the peptide backbone amide bonds that enabled the identification of disulfide-linked peptides. Seven of nine disulfide bonds were definitively assigned; the remaining two bonds were assigned to an adjacent pair of cysteine residues. The first cysteine of surface and the last cysteine of the transmembrane form a disulfide bond linking the heterodimer. The surface glycoprotein contains a free cysteine at residue 38 previously reported to be critical for virus entry. Eleven of 13 possible SUATM129 N-linked glycosylation sites were modified with carbohydrate. This study demonstrates the utility of this simple yet powerful method for assigning disulfide bonds in a complex glycoprotein.

Manufacture of measles viruses

Measles viruses have shown potent oncolytic activity as a therapeutic against a variety of human cancers in animal models and are currently being tested in clinical trials in patients. In contrast to using measles virus as a vaccine, oncolytic activity depends on high concentrations of infectious virus. For use in humans, the high-titer measles virus preparations must also be purified to remove significant levels of cellular proteins and nucleic acid resulting from the cytolytic products of measles virus replication and release. Pleomorphic measles virus must be treated as >1-μm particles that are extremely shear sensitive to maximize recoveries and retain infectivity. Therefore, to maximize the recovery of sterile, high titer infectious measles viruses, the entire production and purification process must be done using gentle conditions and aseptic processing. Here we describe a procedure applicable to the production of small (a few liters) to large (50-60 L) batches of measles virus amplified in Vero cells adapted to serum-free growth. Cell culture supernatant containing the measles virus is clarified by filtration to remove intact Vero cells and other debris, and then treated with Benzonase(®) in the presence of magnesium chloride to digest contaminating nucleic acid. The measles virus in the treated cell culture supernatant is then concentrated and purified using tangential flow filtration (TFF) and diafiltration. The concentrated and diafiltered measles virus is passed through a final clarifying filter prior to final vialing and storage at <-65°C. An infectivity assay to quantify infectious measles virus concentration based on the TCID(50) method is also described. This procedure can be readily adapted to the production and purification of measles viruses using good manufacturing practices (GMP).

Safety studies on intrahepatic or intratumoral injection of oncolytic vesicular stomatitis virus expressing interferon-beta in rodents and nonhuman primates

Toxicology studies were performed in rats and rhesus macaques to establish a safe starting dose for intratumoral injection of an oncolytic vesicular stomatitis virus expressing human interferon-beta (VSV-hIFNbeta) in patients with hepatocellular carcinoma (HCC). No adverse events were observed after administration of 7.59 x 10(9) TCID(50) (50% tissue culture infective dose) of VSV-hIFNbeta into the left lateral hepatic lobe of Harlan Sprague Dawley rats. Plasma alanine aminotransferase and alkaline phosphatase levels increased and platelet counts decreased in the virus-treated animals on days 1 and 2 but returned to pretreatment levels by day 4. VSV-hIFNbeta was also injected into normal livers or an intrahepatic McA-RH7777 HCC xenograft established in Buffalo rats. Buffalo rats were more sensitive to neurotoxic effects of VSV; the no observable adverse event level (NOAEL) of VSV-hIFNbeta in Buffalo rats was 10(7) TCID(50). Higher doses were associated with fatal neurotoxicity and infectious virus was recovered from tumor and brain. Compared with VSV-hIFNbeta, toxicity of VSV-rIFNbeta (recombinant VSV expressing rat IFN-beta) was greatly diminished in Buffalo rats (NOAEL, >10(10) TCID(50)). Two groups of two adult male rhesus macaques received 10(9) or 10(10) TCID(50) of VSV-hIFNbeta injected directly into the left hepatic lobe under computed tomographic guidance. No neurological signs were observed at any time point. No abnormalities (hematology, clinical chemistry, body weights, behavior) were seen and all macaques developed neutralizing anti-VSV antibodies. Plasma interleukin-6, tumor necrosis factor-alpha, and hIFN-beta remained below detection levels by ELISA. On the basis of these studies, we will be proposing a cautious approach to dose escalation in a phase I clinical trial among patients with HCC.

Evaluation of an attenuated vesicular stomatitis virus vector expressing interferon-beta for use in malignant pleural mesothelioma: heterogeneity in interferon responsiveness defines potential efficacy

Abstract Vesicular stomatitis virus (VSV) has shown promise as an oncolytic agent, although unmodified VSV can be neurotoxic. To avoid toxicity, a vector was created by introducing the interferon-beta (IFN-beta) gene (VSV.IFN-beta). We conducted this study to determine the ability of VSV.IFN-beta to lyse human cancer (mesothelioma) cells and to evaluate the potential of this recombinant virus for clinical translation. Four normal human mesothelial and 12 mesothelioma cell lines were tested for their susceptibility to VSV vectors in vitro. VSV.hIFN-beta did not cause cytotoxicity in any normal lines. Only 4 of 12 lines were effectively lysed by VSV.hIFN-beta. In the eight resistant lines, pretreatment with IFN-beta prevented lysis of cells by VSV.GFP, and VSV infection or addition of IFN-beta protein resulted in the upregulation of double-stranded RNA-dependent protein kinase (PKR), myxovirus resistance A (MxA), and 2',5'-oligo-adenylate-synthetase (2'5'-OAS) mRNA. In the susceptible lines, there was no protection by pretreatment with IFN-beta protein and no IFN- or VSV-induced changes in PKR, MxA, and 2'5'-OAS mRNA. This complete lack of IFN responsiveness could be explained by marked downregulation of interferon alpha receptors (IFNARs), p48, and PKR in both the mesothelioma cell lines and primary tumor biopsies screened. Presence of p48 in three tumor samples predicted responsiveness to IFN. Our data indicate that many mesothelioma tumors have partially intact IFN pathways that may affect the efficacy of oncolytic virotherapy. However, it may be feasible to prescreen individual susceptibility to VSV.IFN-beta by immunostaining for the presence of p48 protein.

Phase I trial of intraperitoneal administration of an oncolytic measles virus strain engineered to express carcinoembryonic antigen for recurrent ovarian cancer

Edmonston vaccine strains of measles virus (MV) have shown significant antitumor activity in preclinical models of ovarian cancer. We engineered MV to express the marker peptide carcinoembryonic antigen (MV-CEA virus) to also permit real-time monitoring of viral gene expression in tumors in the clinical setting. Patients with Taxol and platinum-refractory recurrent ovarian cancer and normal CEA levels were eligible for this phase I trial. Twenty-one patients were treated with MV-CEA i.p. every 4 weeks for up to 6 cycles at seven different dose levels (10(3)-10(9) TCID(50)). We observed no dose-limiting toxicity, treatment-induced immunosuppression, development of anti-CEA antibodies, increase in anti-MV antibody titers, or virus shedding in urine or saliva. Dose-dependent CEA elevation in peritoneal fluid and serum was observed. Immunohistochemical analysis of patient tumor specimens revealed overexpression of measles receptor CD46 in 13 of 15 patients. Best objective response was dose-dependent disease stabilization in 14 of 21 patients with a median duration of 92.5 days (range, 54-277 days). Five patients had significant decreases in CA-125 levels. Median survival of patients on study was 12.15 months (range, 1.3-38.4 months), comparing favorably to an expected median survival of 6 months in this patient population. Our findings indicate that i.p. administration of MV-CEA is well tolerated and results in dose-dependent biological activity in a cohort of heavily pretreated recurrent ovarian cancer patients.

Demonstration of anti-tumor activity of oncolytic measles virus strains in a malignant pleural effusion breast cancer model

Breast cancer is the second leading cause of malignant effusions in cancer patients. Pleural effusion indicates incurable disease with limited palliative treatment options and poor outcome. Here, we demonstrate the therapeutic efficacy of measles virus (MV) vaccine strain derivative against malignant pleural effusion in an MDA-MB-231 xenograft model of advanced breast cancer. Both systemic intravenous (i.v.) and intrapleural (t.t.) administered virus caused massive infection and syncytia formation in the pleural tumor deposits. Intrapleural administration of 1.5 x 10(6) plaque-forming units (PFU) total dose of MV significantly improved median survival by approximately 80% compared to the control animal group. Furthermore, we tested human dendritic cells as carriers for delivery of oncolytic MV infection to breast cancer pleural metastases. Carrier-delivered MV infection prevented accumulation of the pleural exudate and also significantly improved the survival of the treated mice. This is the first demonstration of the therapeutic potential of oncolytic virotherapy against malignant pleural effusions in a pre-clinical model of advanced breast cancer.

Toxicology study of repeat intracerebral administration of a measles virus derivative producing carcinoembryonic antigen in rhesus macaques in support of a phase I/II clinical trial for patients with recurrent gliomas

Gliomas have a dismal prognosis, with the median survival of patients with the most common histology, glioblastoma multiforme, being only 12-15 months. Development of novel therapeutic agents is urgently needed. We have previously demonstrated that oncolytic measles virus strains derived from the Edmonston vaccine lineage have significant antitumor activity against gliomas [Phuong, L.K., Allen, C., Peng, K.W., Giannini, C., Greiner, S., Teneyck, C.J., Mishra, P.K., Macura, S.I., Russell, S.J., Galanis, E.C. (2003). Cancer. Res. 63, 2462-2469]. MV-CEA is an Edmonston vaccine lineage measles virus strain engineered to express the marker peptide carcinoembryonic antigen (CEA): CEA levels can serve as a correlate of viral gene expression. In support of a phase I clinical trial of intratumoral and resection cavity administration of MV-CEA to patients with recurrent gliomas, we assessed the neurotoxicity of MV-CEA in adult immune male rhesus macaques (Macaca mulatta). The animals ' immune status and administration schedule mimicked the trial population and proposed administration schema. Macaca mulatta represents the prototype animal species for assessment of measles neurotoxicity. The animals were stereotactically administered either vehicle (n = 1) or MV-CEA at 2 x 10(5)or 2 x 10(6) TCID(50) (each, n = 2) in the right frontal lobe in two injections on days 1 and 5. Macaques were closely monitored clinically for neurotoxicity. Body weight, temperature, complete blood count, CEA, clinical chemistries, coagulation, complement levels, immunoglobulin, measles antibody titers, viremia, and shedding (buccal swabs) were tested at multiple time points. Furthermore, cisterna magna spinal taps were performed on day 9 and 1 year after the first viral dose administration, and samples were analyzed for protein, glucose, cell differential, and presence of MV-CEA. Magnetic resonance imaging (MRI) was performed between 4 and 5 months after article administration to assess for subclinical neurotoxicity. To date, 36+ months from study initiation there has been no clinical or biochemical evidence of toxicity, including lack of neurological symptoms, fever, or other systemic symptoms and lack of immunosuppression. Quantitative RT-PCR analysis of blood, buccal swabs, and cerebrospinal fluid (CSF) was negative for MV-CEA at all time points, with the exception of viral genome deletion in the blood of one asymptomatic animal at the 2 x 10(6) TCID(50) dose level on day 85. Vero cell overlays of CSF cells and supernatant were negative for viral recovery. There was no detection of CEA in serum or CSF at any time point. MRI scans were negative for imaging abnormalities and showed no evidence of encephalitis. Our results support the safety of CNS administration of MV-CEA in glioma patients. A clinical trial of intratumoral and resection cavity administration of MV-CEA in patients with recurrent glioblastoma multiforme is currently ongoing.

Recombinant adeno-associated virus vector for gene transfer to the transplanted rat heart

Efficient durable viral vector transduction of the transplanted heart remains elusive. This study assesses the potential of recombinant adeno-associated virus (rAAV) mediated gene delivery to the transplanted rat heart. rAAV serotype 1, 2 and 5 vectors encoding the green fluorescent protein (GFP) gene (1 x 10(11) viral particles/ml) were diluted in cold University of Wisconsin solution and circulated through the coronary vasculature of the donor organs for 30 min before syngeneic rat heterotopic heart transplantation was performed. Study 1: animals (n = 5 each serotype) were killed at 21 days post-transplant to evaluate the efficiency of GFP transduction using RT-PCR and expression by fluorescence microscopy. Study 2: using rAAV-1, animals (n = 5 each group) were killed at 7, 21 and 84 days to evaluate the durability of GFP expression. The maximum cardiac GFP expression at 21 days was observed in rAAV-1. GFP expression by rAAV-1 was detectable at 7 days, improved at 21 days, and was still evident at 84 days. This study demonstrates cardiac rAAV gene transduction with a cold perfusion preservation system of the donor heart. These data show that AAV-1 is superior to AAV-2 and AAV-5 for this purpose and that durable expression is achievable.

Infected Cell Carriers: A New Strategy for Systemic Delivery of Oncolytic Measles Viruses in Cancer Virotherapy

Attenuated measles viruses (MVs) propagate selectively in human tumor cells, and phase I clinical trials are currently underway to test their oncolytic activity. A major theoretical impediment to systemic MV application is the presence of pre-existing antiviral immunity. We hypothesized that autologous MV-infected cells might be a more reliable vehicle than cell-free virions to deliver the infection to tumor cells in subjects with neutralizing titers of anti-measles antibodies. Our in vitro studies, using a dual-color fluorescent model, demonstrated efficient cell-to-cell transfer of infection via heterofusion. In contrast to infection by naked virions, heterofusion between infected cell carriers and tumor cells was more resistant to antibody neutralization. Infected monocytic, endothelial, or stimulated peripheral blood cells could deliver oncolytic MV to tumor lesions in vivo, after intravenous (i.v.) or intraperitoneal (i.p.) administration. Single or repeated i.p. injections of monocytic carriers significantly improved survival of animals bearing human ovarian cancer xenografts. Systemic or i.p. injection of MV-infected cells successfully transferred infection by heterofusion to Raji lymphomas or hepatocellular carcinoma tumors in the presence of neutralizing antibodies. These results suggest a novel strategy for systemic delivery of oncolytic virotherapy in cancer patients that can "bypass" the pre-existing humoral immunity against MV.

Engineered measles virus as a novel oncolytic viral therapy system for hepatocellular carcinoma

The oncolytic measles virus Edmonston strain (MV-Edm), a nonpathogenic virus targeting cells expressing abundant CD46, selectively destroys neoplastic tissue. Clinical development of MV-Edm would benefit from noninvasive monitoring strategies to determine the speed and extent of the spread of the virus in treated patients and the location of virus-infected cells. We evaluated recombinant MV-Edm expressing carcinoembryonic antigen (CEA) or the human sodium iodide symporter (hNIS) for oncolytic potential in hepatocellular carcinoma (HCC) and efficiency in tracking viruses in vivo by noninvasive monitoring. CD46 expression in human HCC and primary hepatocytes was assessed by flow cytometry and immunohistochemistry. Infectivity, syncytium formation, and cytotoxicity of recombinant MV-Edm in HCC cell lines were evaluated by fluorescence microscopy, crystal violet staining, and the MTS assay. Transgene expression in HCC cell lines after infection with recombinant MV-Edm in vitro and in vivo was assessed by CEA concentration, 125I-uptake, and 123I-imaging studies. Toxicology studies were performed in Ifnar(KO)xCD46 transgenic mice. The CD46 receptor was highly expressed in HCC compared to nonmalignant hepatic tissue. Recombinant MV-Edm efficiently infected HCC cell lines, resulting in extensive syncytium formation followed by cell death. Transduction of HCC cell lines and subcutaneous HCC xenografts with recombinant MV-Edm resulted in high-level expression of transgenes in vitro and in vivo. MV-Edm was nontoxic in susceptible mice. Intratumoral and intravenous therapy with recombinant MV-Edm resulted in inhibition of tumor growth and prolongation of survival with complete tumor regression in up to one third of animals. In conclusion, engineered MV-Edm may be a potent and novel cancer gene therapy system for HCC. MV-Edm expressing CEA or hNIS elicited oncolytic effects in human HCC cell lines in vitro and in vivo, enabling the spread of the virus to be monitored in a noninvasive manner.

Dual therapy of ovarian cancer using measles viruses expressing carcinoembryonic antigen and sodium iodide symporter

PURPOSE

MV-CEA is an oncolytic measles virus currently being tested in patients with ovarian cancer and whose propagation can be monitored by measuring blood carcinoembryonic antigen (CEA) levels. MV-NIS is an oncolytic measles virus coding for the thyroidal sodium iodide symporter (NIS) whose propagation can be mapped by serial radioiodine imaging. Expression of both CEA and NIS genes from a single virus would combine sensitive, quantitative expression monitoring (CEA) with radioisotopic expression mapping (NIS). Because of the unfavorable replication kinetics of measles viruses expressing both CEA and NIS, we explored the feasibility of combining MV-CEA with MV-NIS for comprehensive virotherapy monitoring in ovarian cancer.

EXPERIMENTAL DESIGN AND RESULTS

Mice implanted with i.p. SKOV3ip.1 ovarian cancer xenografts received MV-CEA alone, MV-NIS alone, or a combination of MV-CEA plus MV-NIS. Viral gene expression was monitored by measuring blood CEA levels, and the location of virus-infected cells was monitored by gamma camera imaging. Surprisingly, mice receiving the combination of MV-CEA plus MV-NIS showed greatly superior responses to therapy, but this was associated with 10-fold lower plasma levels of CEA compared with mice treated with MV-CEA alone. In vitro studies showed superior replication kinetics of MV-NIS relative to MV-CEA. The gamma camera scans were considerably less sensitive than the plasma CEA marker for monitoring virus infection.

CONCLUSIONS

Dual therapy with MV-CEA and MV-NIS is superior to treatment with either virus alone, and it allows noninvasive monitoring of virotherapy via soluble marker peptide and gamma camera imaging. This has important implications for the clinical development of oncolytic measles viruses.

Ex vivo hypothermic recirculatory adenoviral gene transfer to the transplanted pig heart

BACKGROUND

To facilitate the application of adenoviral gene therapy in clinical heart transplantation, we developed an ex vivo hypothermic recirculatory adenoviral gene transfer method to the transplanted pig heart.

METHODS

Experimental animals were assigned into three groups; controls, 1x10(8) plaque-forming units (pfu)/ml group and 1x10(9) pfu/ml group. During the 30 min gene transfer perfusion, 200 ml of University of Wisconsin solution containing the adenoviral vector was recirculated through the coronary vessels. The myocardial temperature was maintained below 4 degrees C and the perfusion pressure was adjusted at 50 mmHg.

RESULTS

Cardiac myocyte transduction efficiencies in the 1x10(8) pfu/ml group were 0.04% and 0.07%, whereas transduction efficiencies in the 1x10(9) pfu/ml group were widely distributed from 0.45% to 22.62%. The gene transduction efficiency increased with the virus titer. Additionally, no difference in the transduction efficiency was observed between different segments of the left ventricle. The current gene transfer method at 1x10(9) pfu/ml of adenovirus titer enabled homogeneous gene transduction into the transplanted pig heart up to a maximum of 22.62%.

CONCLUSIONS

This model can be applied to a large isolated heart and will greatly facilitate the investigation of gene therapy in large animal models of heart transplantation.

Immunoglobulin g antibody-mediated enhancement of measles virus infection can bypass the protective antiviral immune response

Antibodies to viral surface glycoproteins play a crucial role in immunity to measles by blocking both virus attachment and subsequent fusion with the host cell membrane. Here, we demonstrate that certain immunoglobulin G (IgG) antibodies can also enhance the entry of measles virus (MV) into monocytes and macrophages. Antibody-dependent enhancement of infectivity was observed in mouse and human macrophages using virions opsonized by a murine monoclonal antibody against the MV hemagglutinin (H) glycoprotein, polyclonal mouse anti-MV IgG, or diluted measles-immune human sera. Neither H-specific Fab fragments nor H-specific IgM could enhance MV entry in monocytes or macrophages, indicating involvement of a Fc gamma receptor (FcgammaR)-mediated mechanism. Preincubation with an anti-fusion protein (anti-F) monoclonal antibody or a fusion-inhibitory peptide blocked infection, indicating that a functional F protein was required for viral internalization. Classical complement pathway activation did not promote infection through complement receptors and inhibited anti-H IgG-mediated enhancement. In vivo, antibody-enhanced infection allowed MV to overcome a highly protective systemic immune response in preimmunized IfnarKo-Ge46 transgenic mice. These data demonstrate a previously unidentified mechanism that may contribute to morbillivirus pathogenesis where H-specific IgG antibodies promote the spread of MV infection among FcgammaR-expressing host cells. The findings point to a new model for the pathogenesis of atypical MV infection observed after immunization with formalin-inactivated MV vaccine and underscore the importance of the anti-F response after vaccination.

Pharmacokinetics of oncolytic measles virotherapy: eventual equilibrium between virus and tumor in an ovarian cancer xenograft model

Because of their ability to replicate, the dose-response relationships of oncolytic viruses cannot easily be predicted. To better understand the pharmacokinetics of virotherapy in relation to viral dose and schedule, we administered MV-CEA intraperitoneally in an orthotopic mouse model of ovarian cancer. MV-CEA is an attenuated oncolytic measles virus engineered to express soluble human carcinoembryonic antigen (CEA), and the virus is currently undergoing phase I clinical testing in patients with ovarian cancer. Plasma CEA levels correlate with numbers of virus-infected tumor cells at a given time, and were used as a surrogate to monitor the profiles of viral gene expression over time. The antineoplastic activity of single- or multiple-dose MV-CEA was apparent over a wide range of virus doses (10(3)-10(8) TCID(50)), with little reduction in observed antitumor efficacy, even at the lowest tested dose. However, analysis of CEA profiles of treated mice was highly informative, illustrating the variability in virus kinetics at different dose levels. The highest doses of virus were associated with higher initial levels of tumor cell killing, but the final outcome of MV-CEA therapy at all dose levels was a partial equilibrium between virus and tumor, resulting in significant slowing of tumor growth and enhanced survival of the mice.

The receptor for the subgroup C avian sarcoma and leukosis viruses, Tvc, is related to mammalian butyrophilins, members of the immunoglobulin superfamily

The five highly related envelope subgroups of the avian sarcoma and leukosis viruses (ASLVs), subgroup A [ASLV(A)] to ASLV(E), are thought to have evolved from an ancestral envelope glycoprotein yet utilize different cellular proteins as receptors. Alleles encoding the subgroup A ASLV receptors (Tva), members of the low-density lipoprotein receptor family, and the subgroup B, D, and E ASLV receptors (Tvb), members of the tumor necrosis factor receptor family, have been identified and cloned. However, alleles encoding the subgroup C ASLV receptors (Tvc) have not been cloned. Previously, we established a genetic linkage between tvc and several other nearby genetic markers on chicken chromosome 28, including tva. In this study, we used this information to clone the tvc gene and identify the Tvc receptor. A bacterial artificial chromosome containing a portion of chicken chromosome 28 that conferred susceptibility to ASLV(C) infection was identified. The tvc gene was identified on this genomic DNA fragment and encodes a 488-amino-acid protein most closely related to mammalian butyrophilins, members of the immunoglobulin protein family. We subsequently cloned cDNAs encoding Tvc that confer susceptibility to infection by subgroup C viruses in chicken cells resistant to ASLV(C) infection and in mammalian cells that do not normally express functional ASLV receptors. In addition, normally susceptible chicken DT40 cells were resistant to ASLV(C) infection after both tvc alleles were disrupted by homologous recombination. Tvc binds the ASLV(C) envelope glycoproteins with low-nanomolar affinity, an affinity similar to that of binding of Tva and Tvb with their respective envelope glycoproteins. We have also identified a mutation in the tvc gene in line L15 chickens that explains why this line is resistant to ASLV(C) infection.