Nanoparticles-mediated dual drug administration boosts therapeutic efficacy in drug resistant melanoma.

Metastatic melanoma remains a critical clinical challenge due to high transcriptional plasticity and the physical barriers of the tumor microenvironment that limit the efficacy of standard therapies. In this study, we present a microfluidic-engineered poly(lactic-co-glycolic acid) nanoparticle (PLGA-NPs) platform designed to maximize therapeutic efficacy through the precise co-encapsulation of synergistic drug combinations. These monodisperse nanocarriers exhibit rapid, dose-dependent internalization across diverse patient-derived models, independent of their mutational background. Mechanistically, we demonstrate that PLGA-NPs uptake is primarily mediated by dynamin-dependent endocytosis and macropinocytosis, followed by a dynamic intracellular trafficking route that reaches a steady-state distribution within recycling endosomes, thereby enabling prolonged intracellular cargo retention. In 3D patient-derived spheroids, these nanoparticles exploit active cell-to-cell transfer consistent with transcytosis-like mechanism to penetrate the poorly accessible central core, effectively bypassing tissue-level resistance and considerably enhancing drug efficacy. In vivo biodistribution in orthotopically transplanted patient-derived xenografts confirmed highly efficient tumor targeting, while a strategic dose-modulation approach successfully optimized the tumor-to-liver accumulation ratio. Therapeutically, twice-weekly intravenous administration of trametinib-loaded NPs achieved superior tumor regression and significantly prolonged overall survival compared to daily oral administration of the free drug. Furthermore, we developed a dual-drug delivery system co-loading trametinib, MEK inhibitor, and alisertib, Aurora A kinase inhibitor. This formulation was optimized to maintain a previously established synergistic ratio which effectively overcome acquired resistance to standard-of-care therapies and induce durable tumor regression. Collectively, these findings establish the PLGA-NPs platform as a robust, clinically relevant strategy to enhance the pharmacokinetic profile of treatments for metastatic and drug-resistant melanoma.