Synergistic apoptosis-sensitizing effect of PD-L1 inhibitor ARB-272572 encapsulated in TRAIL-expressing extracellular vesicles for renal cell carcinoma therapy.

Renal cell carcinoma(RCC) is a therapy-resistant malignancy with rising global incidence, highlighting an urgent need for innovative treatments. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) selectively induces apoptosis in cancer cells, but its clinical translation is hindered by cancer resistance. Extracellular vesicle-delivery of TRAIL (EV-T) has enhanced TRAIL activity. Recent studies reveal that programmed death-ligand 1(PD-L1), beyond its established role in immune evasion, exerts pro-survival functions and mediates TRAIL resistance. Accordingly, we propose the hypothesis that PD-L1 inhibition combined with EV-T may synergistically induce apoptosis in RCC cells. Moreover, we propose EV-based co-delivery of TRAIL and PD-L1 inhibitors could offer a highly efficient therapeutic strategy. First, TRAIL-transduced cells were cultured to prepare EV-Ts. Subsequently, the PD-L1 inhibitor ARB-272572 (ARB) was efficiently encapsulated into EV-Ts via sonication, fabricating a composite nanodrug ARB@EV-T. This formulation demonstrated improved ARB stability, cellular endocytosis, and controlled release kinetics. Importantly, ARB@EV-T overcame TRAIL resistance and showed synergistically enhanced cytotoxicity and apoptosis induction in resistant RCC lines. Mechanistically, the synergistic effect was attributed to upregulation of DR5 and concurrent suppression of anti-apoptotic factors, including cFLIP, MCL-1, BCL-2, XIAP, and Survivin, as well as inhibition of NF-kappaB pathway. In vivo, ARB@EV-T treatment resulted in significant inhibition of tumor proliferation, intense apoptosis, and robust recruitment of natural killer (NK) cells in a subcutaneous RCC xenograft mice model. These effects culminated in substantial tumor regression without any evident adverse events. Collectively, our results demonstrate ARB@EV-T represents an innovative and highly effective therapy against RCC, offering a potential breakthrough for overcoming treatment resistance in RCC.