Multiple myeloma is a radiosensitive malignancy that is currently incurable. Here, we generated a novel recombinant vesicular stomatitis virus [VSV(⌬51) - IntroductionMultiple myeloma is a malignancy of antibody-secreting plasma cells that reside predominantly in bone and bone marrow and secrete a monoclonal immunoglobulin. 1 The disease responds initially to alkylating agents, corticosteroids, and thalidomide, but eventually becomes refractory. 2 Multiple myeloma remains incurable causing more than 10 000 deaths each year in the United States. 3 Although cultured myeloma cells are relatively resistant to radiotherapy in vitro, 4,5 the malignancy is highly radiosensitive and radiation therapy is routinely used for palliation of pain, neurologic compromise, or structural instability from focal myeloma deposits. Efforts to use radiation as a systemic modality for definitive therapy of myeloma, however, have been problematic because of collateral toxicity to normal tissues especially the bone marrow progenitor cells. 6,7 Developing novel therapies for multiple myeloma based on the targeted delivery of radioisotopes to sites of active disease may have important clinical implications for myeloma therapy.Gene transfer using the thyroidal sodium iodide symporter (NIS) gene offers a novel strategy for delivery of radionuclides to disseminated cancer cells. 8 NIS is a transmembrane protein in thyroid follicular cells that actively mediates iodide uptake to a concentration gradient more than 20 to 40-fold. 9 Cloning the human NIS cDNA has aided in imaging and therapy of dedifferentiated thyroid cancer and nonthyroid cancers such as glioma, neuroblastoma, melanoma, multiple myeloma, and ovarian, breast, cervix, lung, liver, and colon carcinoma. 10 Tissue-specific NIS expression has been achieved in various cancer xenografts with minimal toxicity to normal organs by using promoters and enhancers from genes encoding immunoglobulins, prostate-specific antigen, probasin, and mucin-1. [11][12][13][14][15][16] Cancer therapy using oncolytic viruses (oncolytic virotherapy) requires agents that amplify efficiently through replication and spread causing rapid tumor lysis, yet are safe causing minimal toxicity to normal tissue enabling systemic inoculations to treat metastatic cancers. 17,18 We previously engineered the NIS gene into a lymphotropic, replication-competent attenuated strain of measles virus (MV-NIS) 19 that was subsequently used for oncolytic virotherapy of myeloma xenografts. Intratumoral spread of MV-NIS could be monitored noninvasively by radioiodine imaging and virus-resistant tumors were ablated after administration of 131 I. 20 A phase I clinical trial to evaluate the targeting properties of MV-NIS in patients with recurrent or refractory myeloma is ongoing at our institution. Several RNA viruses other than measles virus, including reovirus, Newcastle disease virus, mumps virus, and vesicular stomatitis virus (VSV), are being developed as systemic oncolytic agents for cancer therapy. 18,21 Each of these viruses ...

Radiation doses delivered during ultrafast micro-CT serial imaging in the mouse are low and are likely below the threshold to affect tumor growth.

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-b (VSV-hIFNb) in patients with hepatocellular carcinoma (HCC). No adverse events were observed after administration of 7.59Â10 9 TCID 50 (50% tissue culture infective dose) of VSV-hIFNb 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-hIFNb 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-hIFNb 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-hIFNb, toxicity of VSV-rIFNb (recombinant VSV expressing rat IFN-b) 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-hIFNb 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-a, and hIFN-b 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.

As implemented at the authors' institution, use of CT fluoroscopy for the guidance of interventional radiologic procedures markedly decreased patient radiation dose and total procedure time compared with use of conventional CT guidance.

OBJECTIVE-Our objectives were to, first, determine the oncolytic potential of an engineered measles virus expressing the sodium-iodide symporter gene (MV-NIS) for intratumoral (IT) therapy of pancreatic cancer and, second, evaluate NIS as a reporter gene for in vivo monitoring and quantitation of MV-NIS delivery, viral spread, and gene expression in this tumor model. MATERIALS AND METHODS-Cultured human pancreatic cancer cells were infected with MV-NIS. Light microscopy, cell viability, and iodide uptake assays were used to confirm viral infection and NIS gene expression and function in vitro. Human pancreatic tumor xenografts were established in mice and infected via IT MV-NIS injections. NIS-mediated IT iodide uptake was quantitated by 123 I micro-SPECT/CT. IT MV-NIS infection was confrmed by immunohistochemistry of excised pancreatic xenografts. The oncolytic efficacy of MV-NIS was determined by measurement of tumor growth and mouse survival.RESULTS-Infection of human pancreatic cancer cell lines with MV-NIS in vitro resulted in syncytia formation, marked iodide uptake, and ultimately cell death. Tumor xenografts infected with MV-NIS concentrated radioiodine, allowing serial quantitative imaging with 123 I micro-SPECT/CT. IT MV-NIS therapy of human pancreatic cancer xenografts resulted in a significant reduction in tumor volume and increased survival time of the treated mice compared with the control mice. CONCLUSION-MV-NIS efficiently infects human pancreatic tumor cells and results in sufficientradioiodine uptake to enable noninvasive serial imaging and quantitation of the intensity, distribution, and time course of NIS gene expression. MV-NIS also shows oncolytic activity in human pancreatic cancer xenografts: Tumor growth is reduced and survival is increased in mice treated with the virus. Keywords gene therapy; measles virus; micro-SPECT/CT; molecular imaging; pancreatic cancer; sodiumiodide symporter; viral therapy © American Roentgen Ray Society Address correspondence to S. K. Carlson (E-mail: scarlson@mayo.edu). S. J. Russell is inventor of MV-NIS and Mayo Clinic holds patents on the use of the measles virus for cancer therapy. Pancreatic adenocarcinoma is a hypovascular fibrotic tumor that prevents adequate intratumoral (IT) concentrations of systemically delivered drugs because of high interstitial pressure gradients [3,4]. Previous molecular therapy studies have shown that IT administration achieves a higher IT concentration of the active agent than IV or intraperitoneal delivery [3,5]. Because pancreatic cancer has the propensity for local invasion, a targeted IT approach to therapy may improve local tumor control. NIH Public AccessReplicating viruses have considerable potential as oncolytic agents. In particular, attenuated measles virus of the Edmonston lineage (MV-Edm) has substantial antitumor activity in multiple tumor cell types but produces minimal damage in normal cells [6][7][8][9][10][11]. MV-Edm causes a potent cytopathic effect as a result of massive cell-cell fusion (syncytia ...

OBJECTIVE We have previously shown the therapeutic efficacy of an engineered oncolytic measles virus expressing the sodium iodide symporter reporter gene (MV-NIS) in mice with human pancreatic cancer xenografts. The goal of this study was to determine the synergy between MV-NIS-induced oncolysis and NIS-mediated 131I radiotherapy in this tumor model. MATERIALS AND METHODS Subcutaneous human BxPC-3 pancreatic tumors were injected twice with MV-NIS. Viral infection, NIS expression, and intratumoral iodide uptake were quantitated with 123I micro-SPECT/CT. Mice with MV-NIS infected tumors were treated with 0, 37, or 74 MBq 131I and monitored for tumor progression and survival. Additional studies were performed with stable NIS-expressing tumors (BxPC-3-NIS) treated with 0, 3.7, 18.5, 37, or 74 MBq of 131I. RESULTS Mice treated with intratumoral MV-NIS exhibited significant tumor growth delay (p<0.01) and prolonged survival (p=0.02) compared with untreated mice. Synergy between MV-NIS-induced oncolysis and NIS-mediated 131I ablation was not seen; however, a significant correlation was observed between NIS-mediated intratumoral iodide localization (% ID/g) and peak tumor volume reduction (p=0.04) with combination MV-NIS and 131I therapy. Stably-transduced NIS-expressing BxPC-3 tumors exhibited rapid regression with ≥18.5 MBq 131I. CONCLUSION Delivery of 131I radiotherapy to NIS-expressing tumors can be optimized using micro-SPECT/CT image guidance. Significant hurdles exist for NIS as a therapeutic gene for combined radiovirotherapy in this human pancreatic cancer model. The lack of synergy observed with MV-NIS and 131I in this model was not due to a lack of radiosensitivity, but rather to a non-uniform intratumoral distribution of MV-NIS infection.

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Preclinical and clinical tomographic imaging systems increasingly are being utilized for non-invasive imaging of reporter gene products to reveal the distribution of molecular therapeutics within living subjects. Reporter gene and probe combinations can be employed to monitor vectors for gene, viral, and cell-based therapies. There are several reporter systems available; however, those employing radionuclides for positron emission tomography (PET) or singlephoton emission computed tomography (SPECT) offer the highest sensitivity and the greatest promise for deep tissue imaging in humans. Within the category of radionuclide reporters, the thyroidal sodium iodide symporter (NIS) has emerged as one of the most promising for preclinical and translational research. NIS has been incorporated into a remarkable variety of viral and non-viral vectors in which its functionality is conveniently determined by in vitro iodide uptake assays prior to live animal imaging. This review on the NIS reporter will focus on 1) differences between endogenous NIS and heterologously-expressed NIS, 2) qualitative or comparative use of NIS as an imaging reporter in preclinical and translational gene therapy, oncolytic viral therapy, and cell trafficking research, and 3) use of NIS as an absolute quantitative reporter.