Oncolytic Treatment and Cure of Neuroblastoma by a Novel Attenuated Poliovirus in a Novel Poliovirus-Susceptible Animal Model

Abstract

Neuroblastoma is one of the most common solid tumors in children. Treatment is of limited utility for high-risk neuroblastoma and prognosis is poor. Resistance of neuroblastoma to conventional therapies has prompted us to search for a novel therapeutic approach based on genetically modified polioviruses. Poliovirus targets motor neurons leading to irreversible paralysis. Neurovirulence can be attenuated by point mutations or by exchange of genetic elements between different picornaviruses. We have developed a novel and stable attenuated poliovirus, replicating in neuroblastoma cells, by engineering an indigenous replication element (cre), copied from a genome-internal site, into the 5 ¶-nontranslated genomic region (mono-crePV). An additional host range mutation (A 133 G) conferred replication in mouse neuroblastoma cells (Neuro-2a CD155 ) expressing CD155, the poliovirus receptor. Crossing immunocompetent transgenic mice susceptible to poliovirus (CD155 tg mice) with A/J mice generated CD155 tgA/J mice, which we immunized against poliovirus. Neuro-2a CD155 cells were then transplanted into these animals, leading to lethal tumors. Despite preexisting high titers of anti-poliovirus antibodies, established lethal s.c. Neuro2a CD155 tumors in CD155 tgA/J mice were eliminated by intratumoral administrations of A 133 Gmono-crePV. No signs of paralysis were observed. Interestingly, no tumor growth was observed in mice cured of neuroblastoma that were reinoculated s.c. with CD155 . This result indicates that the destruction of neuroblastoma cells by A 133 Gmono-crePV may lead to a robust antitumor immune response. We suggest that our novel attenuated oncolytic poliovirus is a promising candidate for effective oncolytic treatment of human neuroblastoma or other cancer even in the presence of present or induced antipolio immunity. [Cancer Res 2007;67(6):2857-64]

Oncolytic Poliovirus Therapy in a Mouse Model of Neuroblastoma: Preclinical Data Analysis and Future Studies

“…However, the possibility that poliovirus can cause poliomyelitis calls for significant neuroattenuation to avoid collateral neurologic complications in cancer treatment. Therefore, the aim of our previous study was to develop highly attenuated polioviruses that may be suitable for the treatment of neuroblastoma in children (Toyoda et al, 2007). It was of concern, however, that the high coverage of antipolio vaccination in early childhood may interfere with the application of poliovirus in tumor therapy.…”

“…It was of concern, however, that the high coverage of antipolio vaccination in early childhood may interfere with the application of poliovirus in tumor therapy. Therefore, we also aimed to develop an immunocompetent animal model that would allow us to investigate the oncolytic capacity of neuroattenuated polioviruses for the treatment of neuroblastoma in the presence of high titers of poliovirus neutralizing antibodies (Toyoda et al, 2007). As shown by us and other investigators, pathogenesis of neurotropic viruses including poliovirus can be controlled by translation (Gromeier et al, 1996(Gromeier et al, , 2000Mohr, 2005).…”

“…Cre is absolutely required for poliovirus genome synthesis (Paul, 2002). Based on this concept, we have developed a stable attenuated poliovirus, replicating in neuroblastoma cells, by introducing the cre element into the spacer region between the cloverleaf and IRES in the 5'-NTR (mono-crePV) at the 104-nucleotide locus (Fig 1B) (Toyoda et al, 2007). The polyprotein contains (Nterminus to C-terminus) structural (P1) and non-structural (P2 and P3) proteins that are released from the polypeptide chain by proteolytic processing.…”

“…However, in the nude mice the lack of a possible immune response to the oncolytic agents mitigates the importance of the results. Therefore, we constructed fully immunocompetent mice (CD155 tg A/J mice) that express CD155 and accept Neuro-2a CD155 cells for the formation of lethal neuroblastoma (Toyoda et al, 2007). Using this animal model, we demonstrated that Neuro-2a CD155 subcutaneous tumors of Neuro-2a CD155 cells were eliminated by intratumoral administrations of a variant of mono-crePV (A 133 Gmono-crePV) (Toyoda et al, 2007).…”

“…Therefore, we constructed fully immunocompetent mice (CD155 tg A/J mice) that express CD155 and accept Neuro-2a CD155 cells for the formation of lethal neuroblastoma (Toyoda et al, 2007). Using this animal model, we demonstrated that Neuro-2a CD155 subcutaneous tumors of Neuro-2a CD155 cells were eliminated by intratumoral administrations of a variant of mono-crePV (A 133 Gmono-crePV) (Toyoda et al, 2007). Interestingly, we observed the complete regression of the established lethal subcutaneous Neuro-2a CD155 tumors without neurologic side effects despite the presence of high titers of anti-poliovirus antibodies (Toyoda et al, 2007).…”