PD-1 inhibitor Keytruda combined with chemotherapy for Triple-negative breast cancer (TNBC) has been approved for FDA, successfully representing the combination therapy of immunotherapy and chemotherapy for the first time in 2020. However, PD-L1 inhibitor Tecentriq combined with albumin paclitaxel using the similar strategy failed to achieve the expected effect. Therefore, it is still necessary to explore new effective immunotherapy and chemotherapy-based combined strategies. We developed a cell membrane-derived programmed death-ligand 1(PD-1) nanovesicle to encapsulate low-dose gemcitabine (PD-1&GEM NVs) to study the effect on breast cancer in vitro and in vivo. We found that engineered PD-1&GEM NVs could synergistically inhibit the proliferation of triple-negative breast cancer, which interacted with PD-L1 in triple-negative breast cancer to disrupt the PD-L1/PD-1 immune inhibitory axis and promoted cancer cell apoptosis. Moreover, PD-1&GEM NVs had better tumor targeting ability for PD-L1 highly-expressed TNBC cells, contributing to increasing the drug effectiveness and reducing toxicity. Importantly, gemcitabine-encapsulated PD-1 NVs exerted stronger effects on promoting apoptosis of tumor cells, increasing infiltrated CD8+ T cell activation, delaying the tumor growth and prolonging the survival of tumor-bearing mice than PD-1 NVs or gemcitabine alone. Thus, our study highlighted the power of combined low-dose gemcitabine and PD-1 in the nanovesicles as treatment to treat triple-negative breast cancer.
Keywords: PD-1; breast cancer; gemcitabine; immunotherapy; nanovesicles.