The immune-excluded tumors (IETs) show limited response to current immunotherapy due to intrinsic and adaptive immune resistance. In this study, it is identified that inhibition of transforming growth factor-β (TGF-β) receptor 1 can relieve tumor fibrosis, thus facilitating the recruitment of tumor-infiltrating T lymphocytes. Subsequently, a nanovesicle is constructed for tumor-specific co-delivery of a TGF-β inhibitor (LY2157299, LY) and the photosensitizer pyropheophorbide a (PPa). The LY-loaded nanovesicles suppress tumor fibrosis to promote intratumoral infiltration of T lymphocytes. Furthermore, PPa chelated with gadolinium ion is capable of fluorescence, photoacoustic and magnetic resonance triple-modal imaging-guided photodynamic therapy, to induce immunogenic death of tumor cells and elicit antitumor immunity in preclinical cancer models in female mice. These nanovesicles are further armored with a lipophilic prodrug of the bromodomain-containing protein 4 inhibitor (i.e., JQ1) to abolish programmed death ligand 1 expression of tumor cells and overcome adaptive immune resistance. This study may pave the way for nanomedicine-based immunotherapy of the IETs.
Achieving selective and durable inhibition of programmed death ligand 1 (PD-L1) in tumors for T cell activation remains a major challenge in immune checkpoint blockade therapy. We herein presented a set of clickable inhibitors for spatially confined PD-L1 degradation and radioimmunotherapy of cancer. Using metabolic glycan engineering click bioorthogonal chemistry, PD-L1 expressed on tumor cell membranes was labeled with highly active azide groups. This enables covalently binding of the clickable inhibitor with PD-L1 and subsequent PD-L1 degradation. A pH-activatable nanoparticle responding to extracellular acidic pH of tumor was subsequently used to deliver the clickable PD-L1 inhibitor into extracellular tumor microenvironment for depleting PD-L1 on the surface of tumor cell and macrophage membranes in vivo. We further demonstrated that a combination of the clickable PD-L1 inhibitor with radiotherapy (RT) eradicated the established tumor by inhibiting RT–up-regulated PD-L1 in the tumor tissue. Therefore, selective PD-L1 blockade in tumors via the clickable PD-L1 inhibitor offers a versatile approach to promote cancer immunotherapy.
The antitumor performance of PROteolysis-TArgeting Chimeras (PROTACs) is limited by its insufficient tumor specificity and poor pharmacokinetics. These disadvantages are further compounded by tumor heterogeneity, especially the presence of cancer stem-like cells, which drive tumor growth and relapse. Herein, we design a region-confined PROTAC nanoplatform that integrates both reactive oxygen species (ROS)-activatable and hypoxia-responsive PROTAC prodrugs for the precise manipulation of bromodomain and extraterminal protein 4 expression and tumor eradication. These PROTAC nanoparticles selectively accumulate within and penetrate deep into tumors via response to matrix metalloproteinase-2. Photoactivity is then reactivated in response to the acidic intracellular milieu and the PROTAC is discharged due to the ROS generated via photodynamic therapy specifically within the normoxic microenvironment. Moreover, the latent hypoxia-responsive PROTAC prodrug is restored in hypoxic cancer stem-like cells overexpressing nitroreductase. Here, we show the ability of region-confined PROTAC nanoplatform to effectively degrade BRD4 in both normoxic and hypoxic environments, markedly hindering tumor progression in breast and head-neck tumor models.
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