Genetic Modification of Oncolytic Newcastle Disease Virus for Cancer Therapy

Abstract

Clinical development of a mesogenic strain of Newcastle disease virus (NDV) as an oncolytic agent for cancer therapy has been hampered by its select agent status due to its pathogenicity in avian species. Using reverse genetics, we have generated a lead candidate oncolytic NDV based on the mesogenic NDV-73T strain that is no longer classified as a select agent for clinical development. This recombinant NDV has a modification at the fusion protein IMPORTANCEAvian paramyxovirus type 1, NDV, has been an attractive oncolytic agent for cancer virotherapy. However, this virus can cause epidemic disease in poultry, and concerns about the potential environmental and economic impact of an NDV outbreak have precluded its clinical development. Here we describe generation and characterization of a highly potent oncolytic NDV variant that is unlikely to cause Newcastle disease in its avian host, representing an essential step toward moving NDV forward as an oncolytic agent. Several attenuation mechanisms have been genetically engineered into the recombinant NDV that reduce chicken pathogenicity to a level that is acceptable worldwide without impacting viral production in cell culture. The selective tumor replication of this recombinant NDV, both in vitro and in vivo, along with efficient tumor cell killing makes it an attractive oncolytic virus candidate that may provide clinical benefit to patients.

Newcastle Disease Virus Establishes Persistent Infection in Tumor Cells In Vitro : Contribution of the Cleavage Site of Fusion Protein and Second Sialic Acid Binding Site of Hemagglutinin-Neuraminidase

“…Recombinant NDV (rNDV) used for in vitro passage contained a GFP transgene in the P-M intergenic region in addition to the modified F cleavage site and a 198-nucleotide (nt) insertion in the HN-L intergenic region as described previously (6). rNDV is attenuated in chickens with an intracerebral pathogenicity index (ICPI) of 0.13 ( Table 2).…”

“…The F and HN sequences used here were derived from rNDV-GFP as described previously (6). As shown in Fig.…”

“…These data indicate that the F and HN mutations do not affect IFN production and that IFN levels are not the cause of the defective replication of rNDV-HN 169R . HeLa cells are known to produce a very low level of IFN upon NDV infection and fail to induce ISGs unless prestimulated by treatment with either IFN-␣ or IFN-␥ (6,48,49). HT1080 can produce IFN but is unable to form the IFN-stimulated gene factor 3 (ISGF-3) complex required for a sustained antiviral effect (28).…”

“…rNDV that contains the GM-CSF transgene (termed 73T-R-198 in [6]) and rNDV-GFP viruses have been previously published (6). rNDV-F 117S , rNDV-HN 169R , and rNDV-F 117S /HN 169R were made by introducing the corresponding mutations in rNDV using a QuikChange site-directed mutagenesis kit (Agilent Technologies, Santa Clara, CA).…”

“…The susceptibility of tumor cells to NDV or other oncolytic viruses is likely attributed to changes that have arisen during oncogenesis, including defects in host interferon pathways resulting in an ineffective antiviral response and a concomitant increase in susceptibility to viral infection (4,5). In a previous study, we generated a candidate oncolytic NDV based on a mesogenic NDV 73T strain by reducing avian pathogenicity without compromising the oncolytic potency of the virus (6).…”