MV-NIS is an oncolytic measles virus encoding the human thyroidal sodium iodide symporter (NIS).Here, we report the results of preclinical pharmacology and toxicology studies conducted in support of our clinical protocol "Phase I Trial of Systemic Administration of Edmonston Strain of Measles Virus, Genetically Engineered to Express NIS, with or without Cyclophosphamide, in Patients with Recurrent or Refractory Multiple Myeloma." Dose-response studies in the KAS-6/1 myeloma xenograft model demonstrated a minimum effective dose of 4 × 10 6 TCID 50 (tissue culture infectious dose 50)/kg. Toxicity studies in measles-naive squirrel monkeys and measles-susceptible transgenic mice were negative at intravenous doses up to 10 8 and 4 × 10 8 TCID 50 /kg, respectively. Abundant viral mRNA, maximal on day 8, was detected in cheek swabs of squirrel monkeys, more so after pretreatment with cyclophosphamide. On the basis of these data, the safe starting dose of MV-NIS for our clinical protocol was set at 1 -2 × 10 4 TCID 50 /kg (10 6 TCID 50 per patient).Measles virus (MV, family Paramyxoviridae) was isolated in 1954 from the throat washings of a measles patient, David Edmonston. 1 Tissue culture passage resulted in loss of pathogenicity and attenuation of wild-type MV (Figure 1), giving rise to the Edmonston measles vaccines used worldwide today. 2 We recently discovered that attenuated Edmonston strain MV has potent antitumor activity in vitro and in vivo. 3 Intravenous, intratumoral, or intraperitoneal administration of the virus inhibited tumor growth or induced tumor regression in a variety of human tumor xenograft models. [4][5][6][7] To tailor the virus for cancer therapy, we Correspondence: SJ Russell (sjr@mayo.edu). CONFLICT OF INTERESTThe authors declared no conflict of interest. NIH Public Access Author ManuscriptClin Pharmacol Ther. Author manuscript; available in PMC 2009 October 28. Published in final edited form as:Clin Pharmacol Ther. 2007 December ; 82(6): 700-710. doi:10.1038/sj.clpt.6100409. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscripthave genetically engineered the viral coat protein to display tumor-targeting ligands to enable tumor-specific killing or inserted trackable transgenes into the viral genome to enable noninvasive monitoring of viral gene expression. [8][9][10][11][12] MV-NIS is an Edmonston-lineage MV that expresses the human sodium iodide symporter (hNIS) (Figure 2). 12 The NIS protein is normally expressed in the thyroid, mammary glands, stomach, and salivary tissue. Expression of NIS allows cells to actively transport iodide ions into the cell. Thus, patients with thyroid cancer are typically treated with 131 I to destroy the NIS-expressing thyroid cancer while leaving most normal tissues undamaged. 13 Loss of thyroid function due to the radiotherapy can be treated by replacement therapy with synthetic thyroid hormones. Insertion of NIS into MV facilitates pharmacokinetic evaluation and enhancement of MV oncolytic activity. MV-NIS-infected cells express...

No abstract

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.

Oncolytic measles virus strains have activity against multiple tumor types and are currently in phase I clinical testing. Induction of the heat shock protein 70 (HSP70) constitutes one of the earliest changes in cellular gene expression following infection with RNA viruses including measles virus, and HSP70 upregulation induced by heat shock has been shown to result in increased measles virus cytotoxicity. HSP90 inhibitors such as geldanamycin (GA) or 17-allylaminogeldanamycin result in pharmacologic upregulation of HSP70 and they are currently in clinical testing as cancer therapeutics. We therefore investigated the hypothesis that heat shock protein inhibitors could augment the measles virus-induced cytopathic effect. We tested the combination of a measles virus derivative expressing soluble human carcinoembryonic antigen (MV-CEA) and GA in MDA-MB-231 (breast), SKOV3.IP (ovarian) and TE671 (rhabdomyosarcoma) cancer cell lines. Optimal synergy was accomplished when GA treatment was initiated 6-24 h following MV infection. Western immunoblotting confirmed HSP70 upregulation in combination-treated cells. Combination treatment resulted in statistically significant increase in syncytia formation as compared to MV-CEA infection alone. Clonogenic assays demonstrated significant decrease in tumor colony formation in MV-CEA/GA combination-treated cells. In addition there was increase in apoptosis by 4,6-diamidino-2-phenylindole staining. Western immunoblotting for caspase-9, caspase-8, caspase-3 and poly(ADP-ribose) polymerase (PARP) demonstrated increase in cleaved caspase-8 and PARP. The pan-caspase inhibitor Z-VAD-FMK and caspase-8 inhibitor Z-IETD-FMK, but not the caspase-9 inhibitor Z-IEHD-FMK, protected tumor cells from MV-CEA/GA-induced PARP activation, indicating that apoptosis in combinationtreated cells occurs mainly via the extrinsic caspase pathway. Treatment of normal cells, such as normal human fibroblasts, however, with the MV-CEA/GA combination, did not result in cytopathic effect, indicating that GA did not alter the MV-CEA specificity for tumor cells. One-step viral growth curves, western immunoblotting for MV-N protein expression, QRT-PCR quantitation of MV-genome copy number and CEA levels showed comparable proliferation of MV-CEA in GAtreated vs -untreated tumor cells. Rho activation assays and western blot for total RhoA, a GTPase associated with the actin cytoskeleton, demonstrated decrease in RhoA activation in combination-treated cells, a change previously shown to be associated with increase in paramyxovirus-induced cell-cell fusion. The enhanced cytopathic effect resulting from measles virus/GA combination supports the translational potential of this approach in the treatment of cancer.