High-throughput chemical screening identifies Venetoclax as an enhancer of extracellular vesicle-mediated...

Limited penetration and heterogeneous distribution of nanoparticles (NPs) within solid tumors remain major barriers to the clinical efficacy of cancer nanomedicine. Recent reports have shown the transcellular route as the main pathway for NP extravasation in solid tumors. We previously interrogated the NP transfer from one cell to another, termed intercellular exchange, which is a crucial and yet understudied step of transcellular route. Our results identified extracellular vesicles (EVs) as a critical conduit during NP intercellular exchange, and chemical regulation of EV biogenesis may boost up the activity of this process and lead to a more efficient NP delivery into solid tumors. Here, we set out to determine whether a high throughput chemical screening (HTCS) may be used to rapidly identify novel modulators of NP intercellular exchange. To do so, we adapted our spheroid-based intercellular exchange assay into a HTCS-compatible format. A proof-of-the-principal screen was carried out with the NCI Oncology Drug Library (166 FDA-approved anticancer compounds), which identified Venetoclax as a novel enhancer of NP intercellular exchange across multiple cell types and NP formulations. Venetoclax significantly increased NP transfer in both homotypic tumor-cell and heterotypic endothelial-to-tumor transport systems, leading to enhanced NP penetration in tumor spheroids and increased tumor accumulation and intratumoral distribution in vivo. Mechanistically, Venetoclax increased EV-associated protein output without significantly altering EV size distribution or particle concentration, suggesting modulation of EV cargo composition or functional EV subpopulations rather than global stimulation of EV biogenesis. Together, this study establishes a scalable screening platform for identifying pharmacological regulators of EV-mediated NP transport and demonstrates that enhancing intercellular exchange represents a promising strategy for improving nanoparticle delivery into solid tumors.