Safety Studies on Intrahepatic or Intratumoral Injection of Oncolytic Vesicular Stomatitis Virus Expressing Interferon-β in Rodents and Nonhuman Primates

Abstract

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.

VSV-GP: a Potent Viral Vaccine Vector That Boosts the Immune Response upon Repeated Applications

“…Several groups have engineered VSV mutants with reduced neurotoxicity (18,19), and the level of toxicity/safety in mice of an attenuated VSV variant has been highly predictive of the safety level in nonhuman primates (40,41) (Muik et al, submitted). This lack of toxicity in mice should be predictive of an excellent safety profile for VSV-GP in humans.…”

Ablation of Nectin4 Binding Compromises CD46 Usage by a Hybrid Vesicular Stomatitis Virus/Measles Virus

“…Protein lysates fractionated by 10% acrylamide SDS-PAGE were transferred to a polyvinylidene difluoride membrane (Bio-Rad, Hercules, CA). Membranes were blocked with 5% nonfat milk in Tris-buffered saline (TBS)-Tween for 1 h at room temperature, followed by incubation with primary antibodies, polyclonal rabbit anti-MV-H, polyclonal rabbit anti-MV-F, rabbit anti-human MX1/2/3 (SC-34128; Santa Cruz, Dallas, TX), or polyclonal rabbit anti-VSV proteins (20,21). After five washes in TBS-Tween, membranes were incubated with the appropriate peroxidase-conjugated secondary antibodies.…”

Oncolytic viruses: From bench to bedside with a focus on safety

“…93 A following study testing VSV-hIFNb on rhesus macaques via intrahepatic injection did not result in neurological symptoms and is considered to be safe enough to proceed into phase I clinical trials, which are currently ongoing in humans and pet dogs. 94,95 With regards to shedding, no VSV RNA was detected in buccal swabs taken from non-human primates after intrahepatic injection with VSV-hIFNb. 94 Theoretically, VSV mutants harboring mutations in their M or G gene (making them oncoselective and abolishing neurotropism) could revert to wildtype VSV upon passaging.…”

“…94,95 With regards to shedding, no VSV RNA was detected in buccal swabs taken from non-human primates after intrahepatic injection with VSV-hIFNb. 94 Theoretically, VSV mutants harboring mutations in their M or G gene (making them oncoselective and abolishing neurotropism) could revert to wildtype VSV upon passaging. Also, VSVs expressing attenuating transgenes like hIFNb can acquire mutations in this transgene, which has been shown in several studies.…”