Oncolytic virotherapy is an emerging treatment modality which uses replication competent viruses to destroy cancers. Advances in the past two years include preclinical proof of feasibility for a single-shot virotherapy cure, identification of drugs that accelerate intratumoral virus propagation, new strategies to maximize the immunotherapeutic potential of oncolytic virotherapy, and clinical confirmation of a critical viremic thereshold for vascular delivery and intratumoral virus replication. The primary clinical milestone was completion of accrual in a phase III trial of intratumoral herpes simplex virus therapy using talimogene laherparepvec for metastatic melanoma. Challenges for the field are to select ‘winners’ from a burgeoning number of oncolytic platforms and engineered derivatives, to transiently suppress but then unleash the power of the immune system to maximize both virus spread and anticancer immunity, to develop more meaningful preclinical virotherapy models and to manufacture viruses with orders of magnitude higher yields compared to established vaccine manufacturing processes.

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. Cancer Res; 70(3); 875-82. ©2010 AACR.

MV-NIS is an Edmonston-lineage oncolytic measles virus expressing the human sodium-iodide symporter--a means for monitoring by noninvasive imaging of radioiodine. Patients with relapsed, refractory myeloma who had explored all other treatment options were eligible for this Phase I trial. Cohort 1 was treated with intravenous MV-NIS, and Cohort 2 received cyclophosphamide two days prior to MV-NIS. Thirty-two patients were treated. Cohort 1 initially enrolled to 4 dose-levels without reaching MTD and subsequently to 2 higher dose-levels when improved virus manufacture technology made it possible. MTD was not reached in Cohort 1, and TCID50 1011 is the dose being used in a Phase II trial of single agent MV-NIS. Grade 3–4 AEs in both cohorts at all dose levels were: neutropenia (n=9); leukocyte count decreased (n=5); thrombocytopenia (n=2); and CD4 lymphocytes decreased, anemia and lymphopenia (each n=1). MV-N RNA sequences were amplified from gargle specimens, blood and urine. 123I scans were positive in 8 patients. One patient achieved a CR; transient drops in serum FLCs were seen in other patients. MV-NIS is capable of replicating before being cleared by the immune system. Oncolytic viruses offer a promising new modality for the targeted infection and destruction of disseminated 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.

Biomimetic processes have attracted huge attention in recent years due to their significant applications in biomedical areas such as bone tissue engineering. In the present study, a biomimetic process was employed to form a nanocrystallite apatite coating on metal. A thin bone-like apatite layer was coated onto titanium (Ti) metals via an alkali pre-treatment. This was followed by immersion in a simulated body fluid. Analysis of the coating by thin film x-ray diffraction and scanning electron microscope has shown that the apatite layer grown in this way exhibits nanostructure and has similar stoichiometry to that of natural bone. It is observed that the thickness of the apatite layer increases as the immersion period increases. The growth kinetics and mechanism are also discussed. A cross-sectional study has also shown that a uniform coating of carbonate-containing apatite (hydroxyapatite) is firmly adhered on the Ti metal. The adhesion of the apatite layer on the Ti substrate was further confirmed by a shear test, which has shown an average value of 9.5 MPa. The bioactivity of the coating was finally examined by cell culturing experiments. The results have shown that the nanocomposite prepared using the present method possesses good mechanical properties and bioactivity.

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.

We here describe the development and validation of IMMUNO-COV™, a high-throughput clinical test to quantitatively measure SARS-CoV-2-neutralizing antibodies, the specific subset of anti-SARS-CoV-2 antibodies that block viral infection. The test measures the capacity of serum or purified antibodies to neutralize a recombinant Vesicular Stomatitis Virus (VSV) encoding the SARS-CoV-2 spike glycoprotein. This recombinant virus (VSV-SARS-CoV-2-S-Δ19CT) induces fusion in Vero cell monolayers, which is detected as luciferase signal using a dual split protein (DSP) reporter system. VSV-SARS-CoV-2-S-Δ19CT infection was blocked by monoclonal α-SARS-CoV-2-spike antibodies and by plasma or serum from SARS-CoV-2 convalescing individuals. The assay exhibited 100% specificity in validation tests, and across all tests zero false positives were detected. In blinded analyses of 230 serum samples, only two unexpected results were observed based on available clinical data. We observed a perfect correlation between results from our assay and 80 samples that were also assayed using a commercially available ELISA. To quantify the magnitude of the anti-viral response, we generated a calibration curve by adding stepped concentrations of α-SARS-CoV-2-spike monoclonal antibody to pooled SARS-CoV-2 seronegative serum. Using the calibration curve and a single optimal 1:100 serum test dilution, we reliably measured neutralizing antibody levels in each test sample. Virus neutralization units (VNUs) calculated from the assay correlated closely (p < 0.0001) with PRNTEC50 values determined by plaque reduction neutralization test against a clinical isolate of SARS-CoV-2. Taken together, these results demonstrate that the IMMUNO-COV™ assay accurately quantitates SARS-CoV-2 neutralizing antibodies in human sera and therefore is a potentially valuable addition to the currently available serological tests. The assay can provide vital information for comparing immune responses to the various SARS-CoV-2 vaccines that are currently in development, or for evaluating donor eligibility in convalescent plasma therapy studies.

NIS reporter gene imaging is an excellent technology for noninvasive cell fate determination in living animals unless the NIS-transduced cells reside in perigastric organs such as spleen, liver, diaphragm, omentum, pancreas, perigastric lymph nodes or perigastric tumor deposits. Here we report that orally administered barium sulfate enhances CT definition of the stomach, masks background gamma ray emissions from the stomach, and enhances signal detection from radiotracer uptake in NIS-transduced organs.