Abstract 3043: Preclinical efficacy assessment of brincidofovir against glioblastoma
Authors: Kyounghee Seo, Tomoko Ozawa, David R. Raleigh, Shoji Nagatani, Masatoshi Hazama
Journal: Cancer Research (2025)

Abstract Introduction: Clinical use of the cytidine-analogue antiviral, cidofovir (CDV), is limited by nephrotoxicity. The lipid-conjugated CDV, brincidofovir (BCV), is characterized by a lack of nephrotoxicity, as well as superior activity compared to CDV. The objectives of this study were to examine the preclinical efficacy of BCV against glioblastoma (GBM), a malignant tumor with an extremely poor prognosis, and to identify biomarkers predicting the efficacy of BCV against GBM. Methods: BCV cytotoxicity was tested in vitro in 11 human GBM cell lines, using the CellTiter-Glo® (CTG) assay. Those cell lines were then analyzed by whole-transcriptome sequencing, and differential gene expression analysis between BCV-sensitive and non-BCV sensitive cell lines was performed using DESeq2 software. To examine the influence of O6-methylguanine-DNA methyltransferase (MGMT) expression on BCV sensitivity, monoclonal MGMT-overexpressing cell lines were established using lentiviral vector-based gene transfer in U87MG cells. MGMT gene and protein expression were confirmed using qPCR and western blot, respectively, and the BCV IC50 values were compared among these cell lines using the CTG assay. Finally, the in vivo anti-tumor efficacy of BCV was evaluated in nude mice that were orthotopically implanted with firefly luciferase-transfected U87MG cells. Mice were i.p. administered vehicle or BCV (10, 20, or 40 mg/kg) twice weekly, and bioluminescence imaging (BLI) was performed twice weekly after i.p. D-Luciferin injection to evaluate intracerebral tumor growth. Survival was evaluated using the Kaplan-Meyer method. Results: The CTG assay revealed a median BCV IC50 value of 2.2 μM. Sub-micromolar BCV IC50 values were obtained in KALS-1, T98G, and LN-18 cells. In these highly sensitive cell lines, differential gene expression analysis identified glypican 6 (GPC6) as the gene showing the most significantly decreased expression, and neuronal tyrosine-phosphorylated phosphoinositide-3-kinase adaptor 2 (NYAP2) as the gene with the most significantly increased expression. Compared to the parent MGMT-negative U87MG cells, two MGMT-overexpressing cell lines exhibited BCV IC50 values that were lower by 16.3-fold and 2.5-fold. In vivo experiments demonstrated that BCV significantly decreased intracranial tumor growth, determined as BLI, in a dose-dependent manner during the treatment period compared with the vehicle group. With the exception of weight loss in the BCV 40 mg/kg group, no apparent systemic toxicity was observed in the other BCV dose groups. Compared with the vehicle group, the BCV 20 mg/kg group exhibited significantly increased survival. Conclusion: BCV exerted antitumor effects on GBM in vitro and in vivo, regardless of MGMT status, and improved survival in vivo. Low GPC6 expression and high NYAP2 expression could serve as clinical pharmacologically significant biomarkers that predict high sensitivity to BCV. Citation Format: Kyounghee Seo, Tomoko Ozawa, David R. Raleigh, Shoji Nagatani, Masatoshi Hazama. Preclinical efficacy assessment of brincidofovir against glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3043.