Robust Oncolytic Virotherapy Induces Tumor Lysis Syndrome and Associated Toxicities in the MPC-11 Plasmacytoma Model.

Tumor-selective oncolytic vesicular stomatitis viruses (VSVs) are being evaluated in clinical trials. Here, we report that the MPC-11 murine plasmacytoma model is so extraordinarily susceptible to oncolytic VSVs that a low dose of virus leads to extensive intratumoral viral replication, sustained viremia, intravascular coagulation, and a rapidly fatal tumor lysis syndrome (TLS). Rapid softening, shrinkage and hemorrhagic necrosis of flank tumors was noted within 1-2 days after virus administration, leading to hyperkalemia, hyperphosphatemia, hypocalcemia, hyperuricemia, increase in plasma cell free DNA, lymphopenia, consumptive coagulopathy, increase in fibrinogen degradation products, decreased liver function tests, dehydration, weight loss, and euthanasia or death after 5-8 days. Secondary viremia was observed but viral replication in normal host tissues was not detected. Toxicity could be mitigated by using VSVs with slowed replication kinetics, and was less marked in animals with smaller flank tumors. The MPC-11 tumor represents an interesting model to further study the complex interplay of robust intratumoral viral replication, tumor lysis, and associated toxicities in cases where tumors are highly responsive to oncolytic virotherapy.

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.

Systemic Safety of a Recombinant AAV8 Vector for Human Cocaine Hydrolase Gene Therapy: A Good Laboratory Practice Preclinical Study in Mice.

Cocaine addiction continues to impose major burdens on affected individuals and broader society but is highly resistant to medical treatment or psychotherapy. This study was undertaken with the goal of Food and Drug Administration (FDA) permission for a first-in-human clinical trial of a gene therapy for treatment-seeking cocaine users to become and remain abstinent. The approach was based on intravenous administration of AAV8-hCocH, an adeno-associated viral vector encoding a modified plasma enzyme that metabolizes cocaine into harmless by-products. To assess systemic safety, we conducted "Good Laboratory Practice" (GLP) studies in cocaine-experienced and cocaine-naive mice at doses of 5E12 and 5E13 vector genomes/kg. Results showed total lack of viral vector-related adverse effects in all tests performed. Instead, mice given one injection of AAV8-hCocH and regular daily injections of cocaine had far less tissue pathology than cocaine-injected mice with no vector treatment. Biodistribution analysis showed the vector located almost exclusively in the liver. These results indicate that a liver-directed AAV8-hCocH gene transfer at reasonable dosage is safe, well tolerated, and effective. Thus, gene transfer therapy emerges as a radically new approach to treat compulsive cocaine abuse. In fact, based on these positive findings, the FDA recently accepted our latest request for investigational new drug application (IND 18579).

Oncolytic Virus with Attributes of Vesicular Stomatitis Virus and Measles Virus in Hepatobiliary and Pancreatic Cancers.

Recombinant vesicular stomatitis virus (VSV)-fusion and hemagglutinin (FH) was developed by substituting the promiscuous VSV-G glycoprotein (G) gene in the backbone of VSV with genes encoding for the measles virus envelope proteins F and H. Hybrid VSV-FH exhibited a multifaceted mechanism of cancer-cell killing and improved neurotolerability over parental VSV in preclinical studies. In this study, we evaluated VSV-FH in vitro and in vivo in models of hepatobiliary and pancreatic cancers. Our results indicate that high intrahepatic doses of VSV-FH did not result in any significant toxicity and were well tolerated by transgenic mice expressing the measles virus receptor CD46. Furthermore, a single intratumoral treatment with VSV-FH yielded improved survival and complete tumor regressions in a proportion of mice in the Hep3B hepatocellular carcinoma model but not in mice xenografted with BxPC-3 pancreatic cancer cells. Our preliminary findings indicate that VSV-FH can induce potent oncolysis in hepatocellular and pancreatic cancer cell lines with concordant results in vivo in hepatocellular cancer and discordant in pancreatic cancer without the VSV-mediated toxic effects previously observed in laboratory animals. Further study of VSV-FH as an oncolytic virotherapy is warranted in hepatocellular carcinoma and pancreatic cancer to understand broader applicability and mechanisms of sensitivity and resistance.

New transgenic NIS reporter rats for longitudinal tracking of fibrogenesis by high-resolution imaging.

Fibrogenesis is the underlying mechanism of wound healing and repair. Animal models that enable longitudinal monitoring of fibrogenesis are needed to improve traditional tissue analysis post-mortem. Here, we generated transgenic reporter rats expressing the sodium iodide symporter (NIS) driven by the rat collagen type-1 alpha-1 (Col1α1) promoter and demonstrated that fibrogenesis can be visualized over time using SPECT or PET imaging following activation of NIS expression by rotator cuff (RC) injury. Radiotracer uptake was first detected in and around the injury site day 3 following surgery, increasing through day 7-14, and declining by day 21, revealing for the first time, the kinetics of Col1α1 promoter activity in situ. Differences in the intensity and duration of NIS expression/collagen promoter activation between individual RC injured Col1α1-hNIS rats were evident. Dexamethasone treatment delayed time to peak NIS signals, showing that modulation of fibrogenesis by a steroid can be imaged with exquisite sensitivity and resolution in living animals. NIS reporter rats would facilitate studies in physiological wound repair and pathological processes such as fibrosis and the development of anti-fibrotic drugs.

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)-IFNß-NIS, a novel recombinant oncolytic VSV, can induce curative remission in tumor-bearing mice. Clinical translation of VSV-IFNß-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-IFNß-NIS therapy in pet dogs with spontaneous cancer. Nine dogs with various malignancies were treated with a single intravenous dose of VSV-IFNß-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-IFNß-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-IFNß-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.

Preclinical Development of Oncolytic Immunovirotherapy for Treatment of HPVPOS Cancers.

Immunotherapy for HPVPOS malignancies is attractive because well-defined, viral, non-self tumor antigens exist as targets. Several approaches to vaccinate therapeutically against HPV E6 and E7 antigens have been adopted, including viral platforms such as VSV. A major advantage of VSV expressing these antigens is that VSV also acts as an oncolytic virus, leading to direct tumor cell killing and induction of effective anti-E6 and anti-E7 T cell responses. We have also shown that addition of immune adjuvant genes, such as IFNß, further enhances safety and/or efficacy of VSV-based oncolytic immunovirotherapies. However, multiple designs of the viral vector are possible-with respect to levels of immunogen expression and method of virus attenuation-and optimal designs have not previously been tested head-to-head. Here, we tested three different VSV engineered to express a non-oncogenic HPV16 E7/6 fusion protein for their immunotherapeutic and oncolytic properties. We assessed their profiles of efficacy and toxicity against HPVPOS and HPVNEG murine tumor models and determined the optimal route of administration. Our data show that VSV is an excellent platform for the oncolytic immunovirotherapy of tumors expressing HPV target antigens, combining a balance of efficacy and safety suitable for evaluation in a first-in-human clinical trial.

Safety Study: Intraventricular Injection of a Modified Oncolytic Measles Virus into Measles-Immune, hCD46-Transgenic, IFNαRko Mice.

The modified Edmonston vaccine strain of measles virus (MV) has shown potent oncolytic efficacy against various tumor types and is being investigated in clinical trials. Our laboratory showed that MV effectively kills medulloblastoma tumor cells in both localized disease and when tumor cells are disseminated through cerebrospinal fluid (CSF). Although the safety of repeated intracerebral injection of modified MV in rhesus macaques has been established, the safety of administering MV into CSF has not been adequately investigated. In this study, we assessed the safety of MV-NIS (MV modified to express the human sodium iodide symporter protein) injected into the CSF of measles-immunized and measles virus-susceptible transgenic (CD46, IFNαRko) mice. Treated animals were administered a single intraventricular injection of 1 × 105 or 1 × 106 TCID50 (50% tissue culture infective dose) of MV-NIS. Detailed clinical observation was performed over a 90-day period. Clinically, we did not observe any measles-related toxic effects or behavioral abnormality in animals of any treated cohort. The complete blood count and blood chemistry analysis results were found to be within normal range for all the cohorts. Histologic examination of brains and spinal cords revealed inflammatory changes, mostly related to the needle track; these resolved by day 21 postinjection. To assess viral biodistribution, quantitative RT-PCR to detect the measles virus N-protein was performed on blood and brain samples. Viral RNA was not detectable in the blood as soon as 2 days after injection, and virus cleared from the brain by 45 days postadministration in all treatment cohorts. In conclusion, our data suggest that a single injection of modified MV into the CSF is safe and can be used in future therapeutic applications.

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

Oncolytic VSV-IFNß-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-mIFNß-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-mIFNß-NIS in C57BL/6 mice are 10(10) TCID50/kg and 5 × 10(10) TCID50/kg, respectively. Clinical translation of VSV-IFNß-NIS is underway in companion dogs with cancer and in human patients with relapsed hematological malignancies and endometrial cancer.

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

VSV-IFNß-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-IFNß-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-hIFNß-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.

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.