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Despite the exciting promise of cancer immunotherapy in the clinic, immune checkpoint blockade therapy and T cell-based therapies are often associated with low response rates, intrinsic and adaptive immune resistance, and systemic side effects. CRISPR-Cas-based genome editing appears to be an effective strategy to overcome these unmet clinical needs. As a safer delivery platform for the CRISPR-Cas system, non-viral nanoformulations have been recently explored to target tumor cells and immune cells, aiming to improve cancer immunotherapy on a gene level. In this review, we summarized the efforts of non-viral vector-based CRISPR-Cas-mediated genome editing in tumor cells and immune cells for cancer immunotherapy. Their design rationale and specific applications were highlighted.

Nature contains abundant systems that can significantly alter their structures and properties to adapt to the surrounding environment. Through natural selection and unceasing evolution, hierarchical architectures and sophisticated strategies have been created by nature to achieve optimally adapted materials for biomedical applications. The development of microneedles (MNs) has advanced to the next generation of bioinspired MNs (BMNs), with the goal of improving functions such as amelioration of mechanical properties and tissue adhesion. The biomimetic designs and structures of MNs are highlighted in the present review. This is followed by an in-depth discussion of the fabrication approaches from molding techniques to 3D and 4D printing. The medical applications of BMNs, including drug delivery, regenerative medicine, biopsy sampling, and biosensing, are also discussed. Last, future opportunities and challenges with respect to clinical translation are also deliberated.

Tumor microenvironment (TME), with complex composition, plays a vital role in the occurrence, development, and metastasis of tumors. TME becomes an important obstacle to the accessibility of nanotherapy, thus indicating the need to improve the functional design to overcome this challenge. In this study, we generate an intelligent nano-drug-delivery system (DOX@PssP-Hh NPs) with dual environmental response, which involves heparanase (HPSE) in TME and glutathione (GSH) in tumor cells. The nanosystem consists of a nanoskeleton formed by self-assembly of mPEG-ss-PEI and α-CD (PssP), chemotherapy drug doxorubicin (DOX) for enhancing antitumor efficacy, together with hyaluronidase (HAase), which is designed to degrade extracellular matrix to increase drug penetration, and an outer shell of heparin. Through the process of “responsive disintegration–remodeling tumor microenvironment–enhancing drug penetration–inducing oxidative stress”, the semi-rotaxaneself-assembled nanomicelles were constructed to achieve the progressive function. DOX@PssP-Hh NPs with the size of 81.85 ± 1.85 nm exhibited satisfactory cytotoxicity (IC50= 0.80 ± 0.33 μg/mL). With the disulfide bond-mediated GSH depletion and DOX-mediated reactive oxygen species (ROS) production, treatment with DOX@PssP-Hh NPs prominently reduced glutathione peroxidase 4 (GPX4) level and would lead to enhanced oxidative stresses. Hyaluronic acid (HA), collagen I, and α-smooth muscle actin (α-SMA) were significantly reduced for TME remodulation. Moreover, the antitumor effect in vivo implied that DOX@PssP-Hh NPs could inhibit tumor growth effectively and reduce tumor interstitial fluid pressure (IFP) evidently. In conclusion, DOX@PssP-Hh NPs improved the penetration of drugs and exhibited enhanced antitumor efficacy.

Extracellular matrix (ECM) accumulating in the tumor microenvironment (TME) is generated by tumor-associated fibroblasts. It can elevate interstitial fluid pressure and form dense barriers in tumor tissues. Consequently, nanocarriers are hindered from permeating into deeper tumor sites. Thus, the programmed drug-releasing nanoparticles, G(TM)PPSP, were developed for TME remodeling and breast cancer therapy. Gelatin nanoparticles were linked with platinum nanoparticles (PtNPs) to obtain G(TM)PPSP with a size of 214.0 ± 5.0 nm. Telmisartan (TM) was loaded in gelatin nanoparticles. Paclitaxel (PTX) was attached to PtNPs via a dual redox responsive diselenide bond. TM release was mediated by MMP-2 because of gelatin degradation in TME, and then intracellular PTX was released because of diselenide linkage fracture triggered by ROS or glutathione. ECM was depleted owing to TGF-β downregulation by TM and direct ablation by the photothermal effect of PtNPs. 4T1 tumor progression was inhibited by PTX chemotherapy, intracellular ROS scavenging of PtNPs, and photothermal therapy (PTT). The tumor spheroid penetration assay proved G(TM)PPSP could permeate into deep tumor regions when MMP-2 existed. In vivo antitumor experiments implied G(TM)PPSP with PTT could inhibit tumor growth effectively and remodel TME via ECM depletion and immunity activation, indicating the potential of G(TM)PPSP-based chemo-photothermal combination therapy for breast cancer treatment.

Immune checkpoint blockade (ICB) therapy is a revolutionary approach to treat cancers, but still have limited clinical applications. Accumulating evidence pinpoints the immunosuppressive characteristics of the tumor microenvironment (TME) as one major obstacle. The TME, characterized by acidity, hypoxia and elevated ROS levels, exerts its detrimental effects on infiltrating anti-tumor immune cells. Here, we developed a TME-responsive and immunotherapeutic catalase-loaded calcium carbonate nanoparticles (termed as CAT@CaCO3NPs) as the simple yet versatile multi-modulator for TME remodeling. CaCO3NPs can consume protons in the acidic TME to normalize the TME pH. CAT catalyzed the decomposition of ROS and thus generated O2. The released Ca2+led to Ca2+overload in the tumor cells which then release DAMP signals to initiate anti-tumor immune responses, including tumor antigen presentation by dendritic cells. Meanwhile, CAT@CaCO3NPs-induced immunosupportive TME also promoted the polarization of the M2 tumor-associated macrophages to the M1 phenotype, further enhancing antigen presentation. Consequently, T cell-mediated anti-tumor responses were then activated, the efficacy of which was further boosted by aPD-1 immune checkpoint blockade. Our study demonstrated that local treatment of CAT@CaCO3NPs and aPD-1 combination can effectively evoke local and systemic anti-tumor immune responses, inhibiting the growth of treated tumors and distant diseases.

Ferritin internalized into tumor cells is degraded and releases iron ions via ferritinophagy. Iron ions participate in Fenton reaction to produce reactive oxygen species for lipid peroxidation and ferroptosis. Inhibition of indoleamine‐2,3‐dioxygenase (IDO) decreases tryptophan elimination to induce T cells activation for tumor immunosuppression relief. The active tumor targeting nanoparticles containing ferritin and a pH‐sensitive molecular‐switch (FPBC@SN) are developed to utilize ferritinophagy‐cascade ferroptosis and tumor immunity activation for cancer therapy. FPBC@SN disintegrates in acidic cytoplasm and releases sorafenib (SRF) and IDO inhibitor (NLG919). SRF upregulates nuclear receptor coactivator 4 (NCOA4) to induce ferritin and endogenous iron pool degradation by ferritinophagy, then obtained iron ions participate in the Fenton reaction to produce lipid peroxide (LPO). Meanwhile, SRF blocks glutathione synthesis to downregulate glutathione peroxidase 4 (GPX4) which can scavenge LPO as a different pathway from ferritinophagy to promote ferroptosis in tumor cells. NLG919 inhibits IDO to reduce tryptophan metabolism, so immunity in tumors is aroused to anti‐tumor. In vitro and in vivo experiments prove FPBC@SN inhibits tumor cell growth and metastasis, indicating the potential of FPBC@SN for breast cancer therapy based on the combination of ferritinophagy‐cascade ferroptosis and tumor immunity activation. A kind of novel, actively, tumor targeting, and pH‐responsive nanoparticles, FPBC@SN, is designed and successively developed in this work. Sorafenib and NLG919 (IDO inhibitor) are loaded in FPBC@SN and can massively release in tumor cells. Ferritinophagy‐cascade ferroptosis caused by sorafenib is emphasized here and combined with tumor immunity activation caused by NLG919 for effective breast cancer therapy.