Purpose: Oncolytic virotherapy with herpes simplex virus-1 (HSV) has shown promise for the treatment of pediatric and adult brain tumors; however, completed and ongoing clinical trials have utilized intratumoral/peritumoral oncolytic HSV (oHSV) inoculation due to intraventricular/intrathecal toxicity concerns. Intratumoral delivery requires an invasive neurosurgical procedure, limits repeat injections, and precludes direct targeting of metastatic and leptomeningeal disease. To address these limitations, we determined causes of toxicity from intraventricular oHSV and established methods for mitigating toxicity to treat disseminated brain tumors in mice. Experimental Design: HSV-sensitive CBA/J mice received intraventricular vehicle, inactivated oHSV, or treatment doses (1×107 plaque-forming units) of oHSV, and toxicity was assessed by weight loss and IHC. Protective strategies to reduce oHSV toxicity, including intraventricular low-dose oHSV or interferon inducer polyinosinic-polycytidylic acid (poly I:C) prior to oHSV treatment dose, were evaluated and then utilized to assess intraventricular oHSV treatment of multiple models of disseminated CNS disease. Results: A standard treatment dose of intraventricular oHSV damaged ependymal cells via virus replication and induction of CD8+ T cells, whereas vehicle or inactivated virus resulted in no toxicity. Subsequent doses of intraventricular oHSV caused little additional toxicity. Interferon induction with phosphorylation of eukaryotic initiation factor-2α (eIF2α) via intraventricular pretreatment with low-dose oHSV or poly I:C mitigated ependyma toxicity. This approach enabled the safe delivery of multiple treatment doses of clinically relevant oHSV G207 and prolonged survival in disseminated brain tumor models. Conclusions: Toxicity from intraventricular oHSV can be mitigated, resulting in therapeutic benefit. These data support the clinical translation of intraventricular G207.

Oncolytic virotherapy or immunovirotherapy is a strategy that utilizes viruses to selectively infect and kill tumor cells while also stimulating an immune response against the tumor. Early clinical trials in both pediatric and adult patients using oncolytic herpes simplex viruses (oHSV) have demonstrated safety and promising efficacy; however, combinatorial strategies designed to enhance oncolysis while also promoting durable T-cell responses for sustaining disease remission are likely required. We hypothesized that combining the direct tumor cell killing and innate immune stimulation by oHSV with a vaccine that promotes T cell–mediated immunity may lead to more durable tumor regression. To this end, we investigated the preclinical efficacy and potential synergy of combining oHSV with a self-assembling nanoparticle vaccine codelivering peptide antigens and Toll-like receptor 7 and 8 agonists (referred to as SNAPvax),which induces robust tumor-specific T-cell immunity. We then assessed how timing of the treatments (i.e., vaccine before or after oHSV) impacts T-cell responses, viral replication, and preclinical efficacy. The sequence of treatments was critical, as survival was significantly enhanced when the SNAPvax vaccine was given prior to oHSV. Increased clinical efficacy was associated with reduced tumor volume and increases in virus replication and tumor antigen–specific CD8+ T cells. These findings substantiate the criticality of combination immunotherapy timing and provide preclinical support for combining SNAPvax with oHSV as a promising treatment approach for both pediatric and adult tumors.

Background/Objectives: The purpose of this preclinical pilot study was to explore the potential of green tea extract (GTE) to mitigate and/or prevent oxaliplatin-induced allodynia and axonal damage in rats, when compared to duloxetine (DLX), an ASCO-recommended treatment for established neuropathic pain. Methods: Using a randomized, placebo-controlled experimental design, Sprague Dawley rats (N = 41) received 4 intraperitoneal oxaliplatin (2 mg/kg) injections every other day over 7 days. One week prior to the first oxaliplatin dose, animals began 1 of 4 interventions (saline; GTE 100 mg/kg; DLX 3 mg/kg; GTE 100 mg/kg + DLX 3 mg/kg). A naïve group (n = 6) that received no neurotoxic oxaliplatin or intervention was added to serve as a baseline measure for sNfL. Interventions were administered daily for 4 weeks. Mechanical sensitivity (allodynia) was measured 3 times per week using von Frey testing to determine paw withdrawal thresholds. Von Frey testing began one day prior to the start of interventions to establish baselines and continued through Day 35. Groups were compared to their respective baselines to calculate changes in paw withdrawal thresholds. To measure axonal damage, alterations in serum levels of neurofilament light (sNfL) protein were measured at Day 35 using ELISA. Group differences were identified using two-way analysis of variance (ANOVA). Pearson correlation coefficient was used for correlation analysis between paw withdrawal thresholds and sNfL levels at Day 35. Partial eta-squared and Hedges’ g were used to measure effect sizes. Statistical significance was assigned at P ≤ 0.05 with a 95% confidence interval. Results: Overall, the saline group showed significant reductions in mean paw withdrawal thresholds across experimental timepoints, denoting more severe allodynia caused by oxaliplatin. Conversely, intervention groups exhibited mean paw withdrawal thresholds that were significantly greater than the saline group, indicating less allodynia. The average level of sNfL was also significantly higher in the saline group (113.58 ± 43.84 pg/mL) compared to GTE100 (72.75 ± 26.85), DLX3 (59.93 ± 20.57), and DLX3 + GTE100 (77.04 ± 24.35) intervention groups, suggesting less oxaliplatin-induced axonal damage in these groups. The naïve group exhibited the lowest levels of sNfL (45.69 ± 14.64) when compared to the oxaliplatin-receiving groups (saline and intervention). There were large effect sizes between the saline group, naïve (g = 1.88), GTE100 (g = 1.123), DLX3 (g = 1.157), and DLX3 + GTE100 (g = 1.030) groups. There was also a moderate negative correlation [r(30) = −0.38, p = 0.04] between sNfL levels and paw withdrawal thresholds. Conclusions: The preliminary findings from this pilot study suggest that GTE may be an effective, nutraceutical intervention for mitigating OIPN-associated neuropathic pain, warranting further investigation as an intervention to mitigate chemotherapy-associated neurotoxicities like OIPN.

Toxicity from IVT oHSV in the left lateral ventricle and third and fourth ventricles at different time points.