Serum extracellular vesicles containing adenoviral E1A-DNA as a predictive biomarker for liquid biopsy in oncolytic adenovirus therapy

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Oncolytic adenoviruses replicate selectively in tumor cells and induce immunogenic cell death, but predictive biomarkers for early therapeutic response are lacking. This study evaluated extracellular vesicle-encapsulated adenoviral E1A-DNA (EV-E1A-DNA) as a minimally invasive biomarker for monitoring responses to telomerase-specific oncolytic adenoviruses OBP-301 and OBP-502. EVs were isolated from human and murine cancer cell lines and from the serum of treated mice using ultracentrifugation. EV-associated E1A-DNA levels were measured by quantitative polymerase chain reaction and found to correlate with cytotoxicity in vitro and tumor regression in vivo. In xenograft models, serum EV-E1A-DNA levels at 2 days post-treatment showed strong correlations with final tumor volume and survival, supporting their utility as an early predictive biomarker. In immunocompetent mice pre-immunized with wild-type adenovirus, free viral DNA was undetectable in serum due to neutralizing antibodies, whereas EV-E1A-DNA remained detectable. This "stealth effect" indicates that EVs protect viral components from immune clearance. These results demonstrate that EV-E1A-DNA is a sensitive and virus-specific biomarker that enables early assessment of therapeutic efficacy, even in the presence of antiviral immunity. This strategy offers a promising liquid biopsy approach for personalized monitoring of oncolytic virotherapy and may be applicable to other virus-based therapies.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.