Abstract 2000: The adenovirus Delta-24-RGD in combination with ONC201 provides a therapeutic benefit and a proinflammatory recruitment in preclinical models of pHGGs and DMGs
Authors: de la Nava Daniel , Marco-Sanz Javier , Laspidea Virginia , Labiano Sara , Ausejo-Mauleon Iker , Hernandez-Osuna Reyes , Mueller Sabine , Nazarian Javad , Allen Joshua E. , Becher Oren , Fueyo Juan , Gomez-Manzano Candelaria , Patiño-Garcia Ana , Alonso Marta M. 
Published: June 2022

Abstract
Purpose of the work: Pediatric High Grade Gliomas (pHGGs), including Diffuse Midline Gliomas (DMGs), are very aggressive solid tumors developed during childhood with a poor overall survival underscoring the need for effective treatments. The adenovirus Delta-24RGD and the imipridone ONC201 have demonstrated safety and effectiveness in preclinical models and clinical trials. Thus, we evaluated the therapeutic efficacy of the Delta-24-RGD/ONC201 combination and analyzed possible changes in the tumor microenvironment in preclinical models of pHGGs and DMGs.
Experimental procedures: A battery of pHGGs (SF188 and CHLA-03-AA), human DMG (SU-DIPG IV), and murine DMG cell lines (XFM and NP-53) were used. We assessed the viral replication by hexon titration, the protein expression amount (E1A, fiber, and mTORC1 key proteins)by immunoblotting, and oxygen consumption by Seahorse Analyses. Viability was measured by MTS. CHLA-03-AA and XFM were engrafted orthotopically in athymic nude mice and Balb/c mice, respectively. To assess in vivo efficacy, the animals were treated with Delta-24-RGD (107 PFU/animal) or PBS, followed by ONC201administration (125 mg/kg/twice/weekly). The tumor immune microenvironment was evaluated by flow cytometry.
Results: First, the potential adverse interactions between both agents were checked in vitro, showing that ONC201 cotreatment did not interfere with the Delta-24-RGD replication capacity. As expected, ONC201 treatment led to a reduction in oxygen consumption, which was also observed in the combination treatment. Evaluation of cytotoxicity in a panel of cell lines showed that the combination was significantly better than either agent alone. In vivo, CHLA-03-AA bearing mice treated with the combination showed a significant increase in the median overall survival (PBS: 48 days; ONC201: 54.5 days; Delta-24-RGD: 62 days; Delta-24-RGD/ONC201: 95 days (P=0.0008)), leading to 20%long-term survivors, free of disease. Evaluation of the combination in an immunocompetent orthotopic DMG model also revealed the superior efficacy of the Delta-24-RGD/ONC201 (PBS: 11 days; ONC201: 12 days; Delta-24-RGD: 12 days; ONC201+Delta-24-RGD: 15 days (P=0.02)). Of importance, the combination treatment resulted in the reshaping of the tumor microenvironment towards a proinflammatory phenotype (T cells, NK cells, macrophages, granulocytes, monocytes, dendritic cells, and microglia).
Conclusions: Our data indicate that the combination Delta-24-RGD/ONC201 generates a pro-inflammatory microenvironment that ultimately leads to a superior therapeutic effect in preclinical pHGG and DMGs models.
Citation Format: Daniel de la Nava, Javier Marco-Sanz, Virginia Laspidea, Sara Labiano, Iker Ausejo-Mauleon, Reyes Hernandez-Osuna, Sabine Mueller, Javad Nazarian, Joshua E. Allen, Oren Becher, Juan Fueyo, Candelaria Gomez-Manzano, Ana Patiño-Garcia, Marta M. Alonso. The adenovirus Delta-24-RGD in combination with ONC201 provides a therapeutic benefit and a proinflammatory recruitment in preclinical models of pHGGs and DMGs [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 2000.