Abstract 378: Bioengineering enucleated cell vehicles for tumor targeted intravenous delivery of oncolytic viruses
Authors: White Jeffrey , Wang Huawei , Da Cunha Flavia Franco , Ruchhoeft Maureen , Klemke Richard 
Published: June 2022

Abstract
Metastatic triple negative breast cancer (TNBC) includes poor prognoses and limited effective therapies. The prevalence of systemic micro-metastases is a major barrier to achieving durable clinical outcomes. Oncolytic viruses (OVs) have garnered attention as anti-cancer adjuvants due to their potential for systemic delivery and ability to lyse tumor cells while leaving healthy cells unaffected. Clinical trials have been conducted testing the efficacy of OVs on diverse cancers. Although targeting distributed metastases can be accomplished by intravenous (IV) administration, administration of virus into patient vasculature is inefficient due to the clearance of unprotected viruses by host immunity. There is a major unmet need to develop biocompatible carriers that improve delivery of OVs by circumventing host anti-viral immunity while homing to metastatic lesions. Mesenchymal stem cells (MSCs) are ideal OV carriers as they display innate tumor-trophic properties, propagate OVs, and shield virions from immunity until reaching their target. However, issues need to be addressed before MSCs can deliver OVs to patients: tumor homing needs improved and unmodified MSCs can engraft and contribute to tumor growth and metastasis, raising safety concerns. To address these limitations, our laboratory developed a MSC-derived biodelivery vehicle with enhanced homing abilities to deliver biologics, such as OVs, directly to tumors. Our approach involved using scRNA-seq to identify chemoattractant receptor/ligand pairs (CXCR4/CXCL12, CCR2/CCL2) and endothelial adhesion molecules (PSGL-1/P-E-Selectins) that mediate leukocyte tumor homing and extravasation. We then lentivirally expressed these receptors in MSCs and removed all DNA using ultracentrifugation and Ficoll density gradients. These bioengineered enucleated MSCs (Cargocytes™) have a defined lifespan (4 days) and robustly home to TNBC. This is an important breakthrough as TNBC-trophic Cargocytes can be scaled for clinical applications and are safe for in vivo use as described in our recent publication (Nature Biomedical Engineering, in press). OVs replicate in and lyse interferon-deficient tumor cells while having negligible effects on healthy cells. As the interferon response is absent in enucleated cells, Cargocytes support robust replication of OVs, including oncolytic Herpes Simplex Virus, Measles Virus, and Vesicular Stomatitis Virus (oVSV), allowing IV delivery of high titer OVs to tumors. In in vivo mouse models of metastatic TNBC, carrier-free oVSV fails to infect lung metastases. However, Cargocytes efficiently deliver oVSV to distributed micro-metastases and integrate deep into macro-metastases, evidencing a remarkable improvement in tissue distribution over intra-tumoral injections. Our findings suggest Cargocytes host and target oVSV directly to TNBC, constituting a highly specific OV delivery vehicle.
Citation Format: Jeffrey White, Huawei Wang, Flavia Franco Da Cunha, Maureen Ruchhoeft, Richard Klemke. Bioengineering enucleated cell vehicles for tumor targeted intravenous delivery of oncolytic viruses [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 378.