Semireplication-competent vesicular stomatitis virus as a novel platform for oncolytic virotherapy

Abstract

Among oncolytic viruses, the vesicular stomatitis virus (VSV) is especially potent and a highly promising agent for the treatment of cancer. But, even though effective against multiple tumor entities in preclinical animal models, replication-competent VSV exhibits inherent neurovirulence, which has so far hindered clinical development. To overcome this limitation, replication-defective VSV vectors for cancer gene therapy have been tested and proven to be safe. However, gene delivery was inefficient and only minor antitumor efficacy was observed. Here, we present semireplication-competent vector systems for VSV (srVSV), composed of two trans-complementing, propagation-deficient VSV vectors. The de novo generated deletion mutants of the two VSV polymerase proteins P (phosphoprotein) and L (large catalytic subunit), VSVΔP and VSVΔL respectively, were used mutually or in combination with VSVΔG vectors. These srVSV systems copropagated in vitro and in vivo without recombinatory reversion to replication-competent virus. The srVSV systems were highly lytic for human glioblastoma cell lines, spheroids, and subcutaneous xenografts. Especially the combination of VSVΔG/VSVΔL vectors was as potent as wild-type VSV (VSV-WT) in vitro and induced long-term tumor regression in vivo without any associated adverse effects. In contrast, 90% of VSV-WT-treated animals succumbed to neurological disease shortly after tumor clearance. Most importantly, even when injected into the brain, VSVΔG/VSVΔL did not show any neurotoxicity. In conclusion, srVSV is a promising platform for virotherapeutic approaches and also for VSV-based vector vaccines, combining improved safety with an increased coding capacity for therapeutic transgenes, potentially allowing for multipronged approaches.Electronic supplementary materialThe online version of this article (doi:10.1007/s00109-012-0863-6) contains supplementary material, which is available to authorized users.

Re-engineering Vesicular Stomatitis Virus to Abrogate Neurotoxicity, Circumvent Humoral Immunity, and Enhance Oncolytic Potency

“…Indicated doses of rVSV/rVSV(GP)/rVSV(GP)-GFP were stereotactically injected in 6-week-old female Crl:CD1(ICR) mice (CD-1 mice; Charles River) as described previously (29). PBS-treated mice served as a surgical control.…”

“…RNA from blood and organs was purified using the QIAamp RNA blood and RNeasy Kit, respectively (Qiagen). RNA was reverse transcribed using the High Capacity RNA-tocDNA Kit (Applied Biosystems) and VSV genomic RNA (gRNA) amounts were determined via real-time PCR (n ¼ 2 replicates) using the VSV-specific NPqPCR primer set (29) as well as a PGK1 primer set for internal reference (PGK1f:…”

“…Six-week-old female NOD.CB17-Prkdc scid /J mice (SCID mice; Jackson Laboratories) were inoculated subcutaneously with 10 6 G62 human glioblastoma cells as described previously (29). Once the tumors reached a volume of 0.1 cm 3 , mice were treated intratumorally (i.t.)…”

“…At 48 hours posttreatment, mice were sacrificed and tumors were removed and stored in RNAlater solution. RNA was prepared using the RNeasy Kit and VSV gRNA levels in tumor tissue were determined by quantitative reverse transcriptase PCR (RT-PCR) using the StepOnePlus Real-Time PCR system (Invitrogen) in combination with the VSV-specific NPqPCR primer set (29). gRNA levels were calculated by means of a pVSV-XN2 standard curve.…”

Current Status of Gene Therapy for Brain Tumors∗

“…U87 [100] VSV-M51R VSV M51R Nude, s.c. U87 [101] VSV-rp30 VSV P mut , L mut (VSVwt serial passage) SCID, i.c. U87 [178] srVSV VSV VSV-ΔL + VSVΔG SCID, s.c. G62 [104] Abbreviations:Ad, adenovirus; BDD, γ34.5 beclin-1 binding domain; CEA, carcinoembryonic antigen; CD, cytosine deaminase; EGFR, epidermal growth factor receptor; GBM, glioblastoma; GSC, glioblastoma stem cells; HA, hemagglutinin; HRV2, human rhinovirus type 2; HSV, herpes simplex virus; i.c., intracranial; IRES, internal ribosomal entry site; MV, measles virus; NDV, Newcastle disease virus; NIS, sodium iodide symporter; PNP, purine nucleoside phosphorylase; PV, poliovirus; PVS-RIPO, recombinant poliovirus; RCR, replication competent retrovirus; s.c., subcutaneous; TK, thymidine kinase; TRAIL, tumor necrosis factor-related apoptosis-inducing ligand; VGF, vaccinia growth factor; VSV, vesicular stomatitis virus; VV, vaccinia virus.…”