Chlorin e6 and BLZ945 Based Self-Assembly for Photodynamic Immunotherapy Through Immunogenic Tumor Induction and Tumor-Associated Macrophage Depletion.

Immunotherapeutic effect is restricted by the nonimmunogenic tumor phenotype and immunosuppression behaviors of tumor-associated macrophages (TAMs). In this work, a drug self-assembly (designated as CeBLZ) is fabricated based on chlorin e6 (Ce6) and BLZ945 to activate photodynamic immunotherapy through tumor immunogenic induction and tumor-associated macrophage depletion. It is found that Ce6 tends to assemble with BLZ945 without any drug excipients, which can enhance the cellular uptake, tumor penetration, and blood circulation behaviors. The robust photodynamic therapy effect of CeBLZ efficiently suppresses the primary tumor growth and also triggers immunogenic cell death to reverse the nonimmunogenic tumor phenotype. Moreover, CeBLZ can deplete TAMs in tumor tissues to reverse the immunosuppression microenvironment, activating abscopal effect for distant tumor inhibition. In vitro and in vivo results confirm the superior antitumor effect of CeBLZ with negligible side effect, which might promote the development of sophisticated drug combinations for systematic tumor management.

Chemotherapy-Enabled Colorectal Cancer Immunotherapy of Self-Delivery Nano-PROTACs by Inhibiting Tumor Glycolysis and Avoiding Adaptive Immune Resistance.

The chemo-regulation abilities of chemotherapeutic medications are appealing to address the low immunogenicity, immunosuppressive lactate microenvironment, and adaptive immune resistance of colorectal cancer. In this work, the proteolysis targeting chimera (PROTAC) of BRD4 (dBET57) is found to downregulate colorectal cancer glycolysis through the transcription inhibition of c-Myc, which also inhibits the expression of programmed death ligand 1 (PD-L1) to reverse immune evasion and avoid adaptive immune resistance. Based on this, self-delivery nano-PROTACs (designated as DdLD NPs) are further fabricated by the self-assembly of doxorubicin (DOX) and dBET57 with the assistance of DSPE-PEG2000. DdLD NPs can improve the stability, intracellular delivery, and tumor targeting accumulation of DOX and dBET57. Meanwhile, the chemotherapeutic effect of DdLD NPs can efficiently destroy colorectal cancer cells to trigger a robust immunogenic cell death (ICD). More importantly, the chemo-regulation effects of DdLD NPs can inhibit colorectal cancer glycolysis to reduce the lactate production, and downregulate the PD-L1 expression through BRD4 degradation. Taking advantages of the chemotherapy and chemo-regulation ability, DdLD NPs systemically activated the antitumor immunity to suppress the primary and metastatic colorectal cancer progression without inducing any systemic side effects. Such self-delivery nano-PROTACs may provide a new insight for chemotherapy-enabled tumor immunotherapy.

Carrier-Free Nano-PROTACs to Amplify Photodynamic Therapy Induced DNA Damage through BRD4 Degradation.

Therapy-induced DNA damage is the most common strategy to inhibit tumor cell proliferation, but the therapeutic efficacy is limited by DNA repair machinery. Carrier-free nanoproteolysis targeting chimeras (PROTACs), designed as SDNpros, have been developed to enhance photodynamic therapy (PDT) by blocking the DNA damage repair pathway through BRD4 degradation. Specifically, SDNpros are constructed through noncovalent interactions between the photosensitizer of chlorine e6 (Ce6) and PROTACs of BRD4 degrader (dBET57) via self-assembly. SDNpro has favorable dispersibility and a uniform nanosize distribution without drug excipients. Upon light irradiation, SDNpro produces abundant reactive oxygen species (ROS) to induce DNA oxidative damage. Meanwhile, the DNA repair pathway would be interrupted by the concurrent degradation of BRD4, which could intensify the oxidative DNA damage and elevate PDT efficiency. Beneficially, SDNpro suppresses tumor growth and avoids systemic side effects, providing a promising strategy to promote the clinical translation of PROTACs for tumor treatment.

Cascade Immune Activation of Self-Delivery Biomedicine for Photodynamic Immunotherapy Against Metastatic Tumor.

Photodynamic therapy (PDT) can generate reactive oxygen species (ROS) to cause cell apoptosis and induce immunogenic cell death (ICD) to activate immune response, becoming a promising antitumor modality. However, the overexpressions of indoleamine 2,3-dioxygenase (IDO) and programmed cell death ligand 1 (PD-L1) on tumor cells would reduce cytotoxic T cells infiltration and inhibit the immune activation. In this paper, a simple but effective nanosystem is developed to solve these issues for enhanced photodynamic immunotherapy. Specifically, it has been constructed a self-delivery biomedicine (CeNB) based on photosensitizer chlorine e6 (Ce6), IDO inhibitor (NLG919), and PD1/PDL1 blocker (BMS-1) without the need for extra excipients. Of note, CeNB possesses fairly high drug content (nearly 100%), favorable stability, and uniform morphology. More importantly, CeNB-mediated IDO inhibition and PD1/PDL1 blockade greatly improve the immunosuppressive tumor microenvironments to promote immune activation. The PDT of CeNB not only inhibits tumor proliferation but also induces ICD response to activate immunological cascade. Ultimately, self-delivery CeNB tremendously suppresses the tumor growth and metastasis while leads to a minimized side effect. Such simple and effective antitumor strategy overcomes the therapeutic resistance against PDT-initiated immunotherapy, suggesting a potential for metastatic tumor treatment in clinic.

Photodynamic Therapy Initiated Ferrotherapy of Self-Delivery Nanomedicine to Amplify Lipid Peroxidation via GPX4 Inactivation.

Lipid peroxide (LPO) is the hallmark of ferroptosis, which is a promising antitumor modality for its unique advantages. However, a cellular defense system would weaken the antitumor efficacy of ferrotherapy. Herein, a GPX4 inhibitor of ML162 and a photosensitizer of chlorine e6 (Ce6) are used to prepare the self-delivery nanomedicine (C-ML162) through hydrophobic and electrostatic interactions to enhance ferroptosis by photodynamic therapy (PDT). Specifically, carrier-free C-ML162 improves the solubility, stability, and cellular uptake of antitumor agents. Upon light irradiation, the internalized C-ML162 generates large amounts of reactive oxygen species (ROS) to oxidize cellular unsaturated lipid into LPO. More importantly, C-ML162 can directly inactivate GPX4 to enhance the accumulation of toxic LPO, inducing ferroptotic cell death. Additionally, C-ML162 is capable of accumulating at a tumor site for effective treatment. This self-delivery system to amplify lipid peroxidation via GPX4 inactivation for PDT initiated ferrotherapy might provide an appealing strategy against malignancies.

Self-Delivery Ternary Bioregulators for Photodynamic Amplified Immunotherapy by Tumor Microenvironment Reprogramming.

Abnormal metabolism of cancer cells results in complex tumor microenvironments (TME), which play a dominant role in tumor metastasis. Herein, self-delivery ternary bioregulators (designated as TerBio) are constructed for photodynamic amplified immunotherapy against colorectal cancer by TME reprogramming. Specifically, carrier-free TerBio are prepared by the self-assembly of chlorine e6, SB505124 (SB), and lonidamine (Lon), which exhibit improved tumor accumulation, tumor penetration, and cellular uptake behaviors. Interestingly, TerBio-mediated photodynamic therapy (PDT) could not only inhibit the primary tumor growth but also induce immunogenic cell death of tumors to activate the cascade immune response. Furthermore, TerBio are capable of TME reprograming by SB-triggered transforming growth factor (TGF)-ß blockage and Lon-induced lactic acid efflux inhibition. As a consequence, TerBio significantly suppresses distant and metastatic tumor growth by PDT-amplified immunotherapy. This study might advance the development of self-delivery nanomedicine against malignant tumor growth and metastasis.

Self-Delivery Nanomedicine for Glutamine-Starvation Enhanced Photodynamic Tumor Therapy.

Glutamine metabolism of tumor cells plays a crucial role in maintaining cell homeostasis and reducing oxidative damage. Herein, a valid strategy of inhibiting glutamine metabolism is proposed to amplify the oxidative damage of photodynamic therapy (PDT) to tumor cells. Specifically, the authors develop a drug co-delivery system (designated as CeV) based on chlorine e6 (Ce6) and V9302 via the self-assembly technology. In spite of the strong hydrophobicity of therapeutic agents, the assembled CeV holds a favorable dispersibility in water and an improved cellular uptake capability. Under light irradiation, the internalized CeV is capable of generating abundant reactive oxygen species (ROS) for PDT. More importantly, CeV can reduce the uptake of glutamine through V9302-mediated alanine-serine-cysteine transporter of type-2 (ASCT2) inhibition, leading to a reduced glutathione (GSH) production and an amplified oxidative stress. As a result, CeV has a robust PDT efficacy on tumor inhibition by the blockade of glutamine transport. Notably, CeV exhibits a superiority on tumor suppression over the single treatment as well as the combined administration of Ce6 and V9302, which indicates the advantage of CeV for synergistic treatment. It may serve as a novel nanoplatform for developing a drug co-delivery system to improve PDT efficiency by inhibiting cell metabolism.

Mitochondria Targeted O2 Economizer to Alleviate Tumor Hypoxia for Enhanced Photodynamic Therapy.

Photodynamic therapy (PDT) often suffers from the exacerbated tumor hypoxia and the heterogeneous distribution of photosensitizers, leading to an inefficient ROS productivity and availability. In this work, a mitochondria targeted O2 economizer (designated as Mito-OxE) is developed to improve PDT efficiency by alleviating tumor hypoxia and enhancing the subcellular localization of photosensitizers. Specifically, the photosensitizer of protoporphyrin IX (PpIX) is modified with the hydrophilic polyethylene glycol and the lipophilic cation of triphenylphosphine (TPP) to fabricate the biocompatible mitochondria targeted photosensitizers (designated as Mito-PSs). And Mito-OxE is prepared by using Mito-PSs to load the mitochondrial oxidative phosphorylation inhibitors of atovaquone (ATO). Benefiting from the targeting capability of TPP, Mito-OxE can selectively accumulate in mitochondria after cellular uptake. Subsequently, the mitochondrial respiration would be suppressed to with the participation of ATO, resulting in a local hypoxia mitigation for enhanced PDT. Compared with Mito-PSs, Mito-OxE maximizes the therapeutic effect against hypoxic tumors under light irradiation. This design of mitochondria targeted O2 economizer would advance the development of targeted drug delivery system for effective PDT regardless of hypoxic microenvironment.