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Glioblastoma multiforme (GBM) is the most common human brain cancer. Despite a well-established standard of care, the 5-year mortality rate of GBM patients is 95%, highlighting the need for innovative therapeutic interventions. A variety of oncolytic viruses, including those derived from herpes simplex virus (oHSV), have been designed for GBM therapy, but early-phase clinical trials have reported few complete responses without evidence of durable anti-tumor immunity. Potential reasons for the lack of efficacy are limited vector potency (i.e., virulence) and the presence of a highly immunosuppressive tumor microenvironment (TME) comprised of few activated lymphocytes, large numbers of immunosuppressive myeloid cells (macrophages, myeloid derived suppressor cells [MDSCs], microglia), and an agglomerate of immunosuppressive cytokines (IL-10, VEGF, MIF, etc.). Herein we explore these obstacles by comparing the anti-tumor activity of two different oHSV designs and by arming oHSV with an immunomodulatory payload designed to encourage the development of anti-tumor immunity. We first compared the activities of an HSV-1 KOS strain derivative designated KG4:T124 or colloquially, 2A5B, and an F strain derivative designated rQNestin34.5v.1 (a similar oHSV, rQNestin34.5v.2, is currently in a phase I clinical trial for GBM). We evaluated viral entry, replication capacity, and cytotoxicity using both murine and human glioma cell lines in vitro. Viral entry was relatively similar between both vectors, but rQNestin34.5v.1 replicated more effectively and generally induced greater viral mediated cytotoxicity. In syngeneic mice, rQNestin34.5v.1 reduced orthotopic GL261N4 tumor burden compared to 2A5B, but neither virus impeded disease progression in the more pernicious CT2A model. Evaluation of either the GL261N4 or CT2A TME revealed that both viruses induced a high influx of tumor associated macrophages, a transient polymorphonuclear (PMN) cell population, but did not alter the frequency of monocytic MDSCs. As a strategy to enhance oHSV efficacy, we sought to differentiate the highly immunosuppressive MDSC population into pro-inflammatory macrophages using oHSV armed with IL-12, a cytokine that has been shown to provide this activity. We show that oHSV:IL-12 induced a significant increase in tumor-associated macrophages and increased the survival of animals bearing either tumor type. Although we observed a low percentage of complete responses with the presence of anti-tumor CTLs demonstrated by tumor rechallenge experiments, IL-12 alone was not sufficient to significantly improve overall long-term animal survival, suggesting that additional arming genes should be considered in combination with IL-12. Citation Format: Joseph W. Jackson, Bonnie L. Hall, Lisa Bailey, Christophe Quéva, E. Antonio Chiocca, Justus B. Cohen, Joseph C. Glorioso. Comparison of Two oHSV Vectors for the Treatment of Glioblastoma [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO089.

Since its discovery in 1995, TNF-related apoptosis-inducing ligand (TRAIL) has sparked growing interest among oncologists due to its remarkable ability to induce apoptosis in malignant human cells, but not in most normal cells. However, one major drawback is its fast clearance rate in vivo. Thus, the development of an alternative means of delivery may increase the effectiveness of TRAIL-based therapy. In this study, we developed a secretory TRAIL-armed natural killer (NK) cell–based therapy and assessed its cytotoxic effects on colorectal cancer cells and its tumoricidal efficacy on colorectal peritoneal carcinomatosis xenograft. We generated genetically modified NK cells by transduction with a lentiviral vector consisting of a secretion signal domain, a trimerization domain, and an extracellular domain of the TRAIL gene. These NK cells secreted a glycosylated form of TRAIL fusion protein that induced apoptotic death. Intraperitoneally, but not intravenously, injected NK cells effectively accumulated at tumor sites, infiltrated tumor tissue, induced apoptosis, and delayed tumor growth. These results shed light on the therapeutic potential of genetically engineered NK cells to treat peritoneal carcinomatosis. Mol Cancer Ther; 15(7); 1591–601. ©2016 AACR.

Introduction: Cervical cancer is the second most common cancer in women worldwide. In the US there will be approximately 12,360 new cases and 4,040 deaths in 2014. Treatment of locally advanced disease with concomitant- chemoradiation is suboptimal and leaves 40% of patients with residual disease. There are limitations on the total radiation dose that can be administered. There has been little progress examining novel therapeutic modalities for locally advanced cervical cancer. Photodynamic therapy (PDT) is a potential adjuvant to standard treatment. PDT requires a light source, a photosensitizer and oxygen to generate reactive oxygen species that kill cells. Silicon phthalocyanine 4 (Pc 4) is a second generation photosensitizer that has been evaluated in clinical trials. In this study we evaluated the effectiveness of in vitro Pc 4 PDT in human cervical cancer cells. Methods: CaSki and ME180, human metastatic cervical cancer cell lines expressing epidermal growth factor receptor (EGRF), were obtained from ATCC. Cells (104 cells/100 μL) were grown as monolayers in 96 well plates in RPMI 1640 medium without phenol red containing 100 IU Penicillin and 100 μg/ ml Streptomycin at 37°C, 5% CO2, 95% humidity. Cell growth was measured using a Methylthiazol Tetrazolium (MTT) assay. Pc 4 cellular uptake was determined at 0.3 μM Pc 4 by fluorescence back calculated against Pc 4 standard curves (excitation 350 nm, emission 670 nm) and expressed as % Pc 4. For the Pc 4 PDT experiments, concentrations of Pc 4 from 0.001 to 10 μM were added starting 24 hours after cells were plated. Forty-eight hours after Pc 4 addition, cells were irradiated with a diode laser at 667 nm at a fluence of 2.5 J/cm2. A control plate was shielded from the laser. Twenty-four hours after PDT, cell viability was assessed via MTT assay. Percent inhibition was calculated from observed data and the IC50 was calculated from the Hill equation using ADAPT 5. Confocal imaging was performed to determine the intracellular distribution of Pc 4; mitochondria and lysosomes were imaged using MitoTracker® (Cell Signaling) and LysoTracker® (Life Technologies), respectively. Results: ME180 cells have a doubling time of approximately 21 hours, while CaSki cells double in approximately 48 hours. Pc 4 is taken up by each cell line and the majority of uptake occurs by approximately 6 hours. Pc 4 was not toxic to the cells at concentration below 10 μM. Following Pc 4 PDT, the IC50s for CaSki and ME180 cells were, respectively, 0.413 μM (%CV 11.9) and 0.088 μM (%CV 119,000). Pc 4 distributed throughout the cells, overlapping with both the mitochondrial and lysosomal markers, as well being present within the cytoplasm. Conclusion: Pc4 PDT is effective for the treatment of human cervical cancer cells. Additional studies will evaluate Pc 4 PDT using EGFR targeted, Pc 4 loaded nanoparticles as well as cervical cancer spheroids. Support: P30-CA47904, CTSI BaCCoR Pilot Program Citation Format: Jill A. Gadzinski, Brian Philips, Per Basse, Jianxia Guo, Anirban Sen Gupta, Lisa Bailey, John T. Comerci, Julie L. Eiseman. Evaluation of silicon phthalocyanine 4 photodynamic therapy in human cervical cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3313. doi:10.1158/1538-7445.AM2015-3313