Multitargeting Prodrugs that Release Oxaliplatin, Doxorubicin and Gemcitabine are Potent Inhibitors of Tumor Growth and Effective Inducers of Immunogenic Cell Death

CuPc-Fe@BSA nanocomposite: Intracellular acid-sensitive aggregation for enhanced sonodynamic and chemo-therapy

Due to their rigid π-conjugated macrocyclic structure, organic sonosensitizers face significant aggregation in physiological conditions, hindering the production of reactive oxygen species (ROS). An acid-sensitive nanoassembly was developed to address this issue and enhance sonodynamic therapy (SDT) and emission. Initially, copper phthalocyanine (CuPc) was activated using a H2SO4-assisted hydrothermal method to introduce multiple functional groups (-COOH, -OH, and -SO3H), disrupting strong π-π stacking and promoting ROS generation and emission. Subsequently, negatively charged CuPc-SO4 was incorporated into bovine serum albumin (BSA) to form CuPc-Fe@BSA nanoparticles (10 nm) with Fe3+ ions serving as linkers. In acidic conditions, protonation of CuPc-SO4 and BSA weakened the interactions, leading to Fe3+ release and nanostructure dissociation. Protonated CuPc-SO4 tended to self-aggregate into nanorods. This acidity-sensitive aggregation is vital for achieving specific accumulation within the tumor microenvironment (TME), thereby enhancing retention and SDT efficacy. Prior to this, the nanocomposites demonstrated cycling stability under neutral conditions. Additionally, the released Fe ions exhibited mimicry of glutathione peroxidase and peroxidase activity for chemotherapy (CDT). The synergistic effect of SDT and CDT increased intracellular oxidative stress, causing mitochondrial injury and ferroptosis. Furthermore, the combined therapy induced immunogenic cell death (ICD), effectively activating anticancer immune responses and suppressing metastasis and recurrence.

Engineered Carrier-Free Nanosystem-Induced In Situ Therapeutic Vaccines for Potent Cancer Immunotherapy

In situ vaccines that can stimulate tumor immune response have emerged as a breakthrough in antitumor therapy. However, the immunosuppressed tumor microenvironment and insufficient infiltration of immune cells lead to ineffective antitumor immunity. Hence, a biomimetic carrier-free nanosystem (BCC) to induce synergistic phototherapy/chemotherapy-driven in situ vaccines was designed. A carrier-free nanosystem was developed using phototherapeutic reagents CyI and celastrol as raw materials. In vitro and in vivo studies have shown that under NIR light irradiation, BCC-mediated photo/chemotherapy not only accelerates the release of drugs to deeper parts of tumors, achieving timing and light-controlled drug delivery to result in cell apoptosis, but also effectively stimulates the antitumor response to induce in situ vaccine, which could invoke long-lasting antitumor immunity to inhibit tumor metastasis and eliminate distant tumor. This therapeutic strategy holds promise for priming robust innate and adaptive immune responses, arresting cancer progression, and inducing tumor dormancy.

A NIR-Light-Activated and Lysosomal-Targeted Pt(II) Metallacycle for Highly Potent Evoking of Immunogenic Cell Death that Potentiates Cancer Immunotherapy of Deep-Seated Tumors

Though platinum (Pt)-based complexes have been recently exploited as immunogenic cell death (ICD) inducers for activating immunotherapy, the effective activation of sufficient immune responses with minimal side effects in deep-seated tumors remains a formidable challenge. Herein, we propose the first example of a near-infrared (NIR) light-activated and lysosomal targeted Pt(II) metallacycle (1) as a supramolecular ICD inducer. 1 synergistically potentiates immunomodulatory response in deep-seated tumors via multiple-regulated approaches, involving NIR light excitation, boosted reactive oxygen species (ROS) generation, good selectivity between normal and tumor cells, and enhanced tumor penetration/retention capabilities. Specifically, 1 has excellent depth-activated ROS production (~7 mm), accompanied by strong anti-diffusion and anti-ROS quenching ability. In vitro experiments demonstrate that 1 exhibits significant cellular uptake and ROS generation in tumor cells as well as respective multicellular tumor spheroids. Based on these advantages, 1 induces a more efficient ICD in an ultralow dose (i.e., 5 μM) compared with the clinical ICD inducer-oxaliplatin (300 μM). In vivo, vaccination experiments further demonstrate that 1 serves as a potent ICD inducer through eliciting CD8+/CD4+ T cell response and Foxp3+ T cell depletion with negligible adverse effects. This study pioneers a promising avenue for safe and effective metal-based ICD agents in immunotherapy.

Exploring a Gemcitabine-Glucose Hybrid as a Glycoconjugate Prodrug

Nucleoside analogues are established treatments for cancer and viral infection. Gemcitabine is a commonly employed nucleoside analogue displaying anticancer properties against a range of tumor types but is rapidly inactivated in vivo. Efforts to bolster its pharmaceutical profile include investigating prodrug forms. Herein, we explore the synthesis of a novel glucose-gemcitabine glycoconjugate, targeting uptake via glucose transport. We select a redox-reactive disulfide linker for conjugation of gemcitabine (through N4-cytosine) with glucose. Evaluation of this glycoconjugate reveals increased toxicity against androgen insensitive PC3 prostate cancer cells compared to LNCaP (which have lower levels of glucose transporter GLUT1). These preliminary results suggest that glycoconjugation of nucleosides may be an effective approach to targeting cells which display increased uptake and metabolism of glucose.

"Find Me" and "Eat Me" signals: tools to drive phagocytic processes for modulating antitumor immunity

Phagocytosis, a vital defense mechanism, involves the recognition and elimination of foreign substances by cells. Phagocytes, such as neutrophils and macrophages, rapidly respond to invaders; macrophages are especially important in later stages of the immune response. They detect "find me" signals to locate apoptotic cells and migrate toward them. Apoptotic cells then send "eat me" signals that are recognized by phagocytes via specific receptors. "Find me" and "eat me" signals can be strategically harnessed to modulate antitumor immunity in support of cancer therapy. These signals, such as calreticulin and phosphatidylserine, mediate potent pro-phagocytic effects, thereby promoting the engulfment of dying cells or their remnants by macrophages, neutrophils, and dendritic cells and inducing tumor cell death. This review summarizes the phagocytic "find me" and "eat me" signals, including their concepts, signaling mechanisms, involved ligands, and functions. Furthermore, we delineate the relationships between "find me" and "eat me" signaling molecules and tumors, especially the roles of these molecules in tumor initiation, progression, diagnosis, and patient prognosis. The interplay of these signals with tumor biology is elucidated, and specific approaches to modulate "find me" and "eat me" signals and enhance antitumor immunity are explored. Additionally, novel therapeutic strategies that combine "find me" and "eat me" signals to better bridge innate and adaptive immunity in the treatment of cancer patients are discussed.

A Synergistic Chemoimmunotherapy System Leveraging PD-L1 Blocking and Bioorthogonal Prodrug Activation

Novel strategies to facilitate tumor-specific drug delivery and restore immune attacks remain challenging in overcoming the current limitations of chemoimmunotherapy. An antitumor chemoimmunotherapy system comprising bioorthogonal reaction-ready group tetrazine (TZ) modified with an anti-PD-L1 antibody (αPD-L1TZ) and TZ-activatable prodrug vinyl ether-doxorubicin (DOX-VE) for self-reinforced anti-tumor chemoimmunotherapy is proposed. The αPD-L1TZ effectively disrupts the PD-L1/PD-1 interaction and activates the DOX prodrug in situ through the bioorthogonal click reaction of TZ and VE. Conversely, the activated DOX upregulates PD-L1 on the surface of tumor cells, facilitating tumor accumulation of αPD-L1TZ and enhancing DOX-VE activation. Furthermore, the activated DOX-induced immunogenic cell death of tumor cells, substantially improving the response efficiency of αPD-L1 in an immune-suppressive tumor microenvironment. Thus, PD-L1 blocking and bioorthogonal in situ prodrug activation synergistically enhance the antitumor efficacy of the chemoimmunotherapy system. Therefore, the system significantly enhances αPD-L1 tumor accumulation and prodrug activation and induces a robust immunological memory effect to prevent tumor recurrence and metastasis. Thus, a feasible chemoimmunotherapy combination regimen is presented.

A Carbon-Caged Rhodamine Generating Nitrosoperoxycarbonate for Photoimmunotherapy

Photoimmunotherapy is a promising cancer treatment modality. While potent 1-e- oxidative species are known to induce immunogenic cell death (ICD), they are also associated with unspecific oxidation and collateral tissue damage. This difficulty may be addressed by post-generation radical reinforcement. Namely, non-oxidative radicals are first generated and subsequently activated into powerful oxidative radicals to induce ICD. Here, we developed a photo-triggered molecular donor (NPCD565) of nitrosoperoxycarbonate (ONOOCO2 -), the first of its class to our knowledge, and further evaluated its feasibility for immunotherapy. Upon irradiation of NPCD565 by light within a broad spectral region from ultraviolet to red, ONOOCO2 - is released along with a bright rhodamine dye (RD565), whose fluorescence is a reliable and convenient build-in reporter for the localization, kinetics, and dose of ONOOCO2 - generation. Upon photolysis of NPCD565 in 4T1 cells, damage-associated molecular patterns (DAMPs) indicative of ICD were observed and confirmed to exhibit immunogenicity by induced maturation of dendritic cells. In vivo studies with a bilateral tumor-bearing mouse model showcased the potent tumor-killing capability of NPCD565 of the primary tumors and growth suppression of the distant tumors. This work unveils the potent immunogenicity of ONOOCO2 -, and its donor (NPCD565) has broad potential for photo-immunotherapy of cancer.

Novel NF-κB Inhibitor-Conjugated Pt(IV) Prodrug to Enable Cancer Therapy through ROS/ER Stress and Mitochondrial Dysfunction and Overcome Multidrug Resistance

Although cisplatin has been widely used for clinical purposes, its application is limited due to its obvious side effects. To mitigate the defects of cisplatin, here, six "multitarget prodrugs" were synthesized by linking cisplatin and NF-κB inhibitors. Notably, complex 9 demonstrated a 63-fold enhancement in the activity against A549/CDDP cells with lower toxicity toward normal LO2 cells compared to cisplatin. Additionally, complex 9 could effectively cause DNA damage, induce mitochondrial dysfunction, generate reactive oxygen species, and induce cell apoptosis through the mitochondrial pathway and ER stress. Remarkably, complex 9 effectively inhibited the NF-κB/MAPK signaling pathway and disrupted the PI3K/AKT signaling transduction. Importantly, complex 9 showed superior in vivo antitumor efficiency compared to cisplatin or the combination of cisplatin/4, without obvious systemic toxicity in A549 or A549/CDDP xenograft models. Our results demonstrated that the dual-acting mechanism endowed the complexes with high efficiency and low toxicity, which may represent an efficient strategy for cancer therapy.

Oxaliplatin(IV) Prodrugs Functionalized with Gemcitabine and Capecitabine Induce Blockage of Colorectal Cancer Cell Growth-An Investigation of the Activation Mechanism and Their Nanoformulation

The use of platinum-based anticancer drugs, such as cisplatin, oxaliplatin, and carboplatin, is a common frontline option in cancer management, but they have debilitating side effects and can lead to drug resistance. Combination therapy with other chemotherapeutic agents, such as capecitabine and gemcitabine, has been explored. One approach to overcome these limitations is the modification of traditional Pt(II) drugs to obtain new molecules with an improved pharmacological profile, such as Pt(IV) prodrugs. The design, synthesis, and characterization of two novel Pt(IV) prodrugs based on oxaliplatin bearing the anticancer drugs gemcitabine or capecitabine in the axial positions have been reported. These complexes were able to dissociate into their constituents to promote cell death and induce apoptosis and cell cycle blockade in a representative colorectal cancer cell model. Specifically, the complex bearing gemcitabine resulted in being the most active on the HCT116 colorectal cancer cell line with an IC50 value of 0.49 ± 0.04. A pilot study on the encapsulation of these complexes in biocompatible PLGA-PEG nanoparticles is also included to confirm the retention of the pharmacological properties and cellular drug uptake, opening up to the possible delivery of the studied complexes through their nanoformulation.

Multifunctional ZnO@DOX/ICG-LMHP Nanoparticles for Synergistic Multimodal Antitumor Activity

Multifunctional nanoparticles are of significant importance for synergistic multimodal antitumor activity. Herein, zinc oxide (ZnO) was used as pH-sensitive nanoparticles for loading the chemotherapy agent doxorubicin (DOX) and the photosensitizer agent indocyanine green (ICG), and biocompatible low-molecular-weight heparin (LMHP) was used as the gatekeepers for synergistic photothermal therapy/photodynamic therapy/chemotherapy/immunotherapy. ZnO was decomposed into cytotoxic Zn2+ ions, leading to a tumor-specific release of ICG and DOX. ZnO simultaneously produced oxygen (O2) and reactive oxygen species (ROS) for photodynamic therapy (PDT). The released ICG under laser irradiation produced ROS for PDT and raised the tumor temperature for photothermal therapy (PTT). The released DOX directly caused tumor cell death for chemotherapy. Both DOX and ICG also induced immunogenic cell death (ICD) for immunotherapy. The in vivo and in vitro results presented a superior inhibition of tumor progression, metastasis and recurrence. Therefore, this study could provide an efficient approach for designing multifunctional nanoparticles for synergistic multimodal antitumor therapy.

Dihydroartemisinin inhibits liver cancer cell migration and invasion by reducing ATP synthase production through CaMKK2/NCLX

Calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2) and mitochondrial sodium/calcium exchanger protein (NCLX) are key regulatory factors in calcium homeostasis. Finding natural drugs that target regulators of calcium homeostasis is critical. Dihydroartemisinin (DHA) is considered to have anticancer effects. The present study aimed to investigate the mechanism of DHA in regulating liver cancer migration and invasion. The present study used HepG2 and HuH-7 cells and overexpressed CaMKK2 and knocked down CaMKK2 and NCLX. The antiproliferative activity of DHA on liver cancer cells was assessed through colony formation and EdU assays. Cell apoptosis was detected through YO-PRO-1/PI staining. The levels of reactive oxygen species (ROS) were measured using a ROS detection kit (DCFH-DA fluorescent probe). Cell migratory and invasive abilities were examined using wound healing and Transwell assays. The ATP production of liver cancer cells was detected using ATP fluorescent probes. Cell microfilaments were monitored for changes using Actin-Tracker Green-488. The effects of DHA on the expression of CaMKK2, NCLX, sodium/potassium-transporting ATPase subunit α-1 (ATP1A1) and ATP synthase subunit d, mitochondrial (ATP5H) were determined by western blotting and reverse transcription-quantitative PCR. The results revealed that DHA significantly inhibited proliferation, reduced ROS levels and promoted apoptosis in liver cancer cells. CaMKK2 overexpression significantly enhanced the invasive and migratory ability of liver cancer cells, whereas DHA inhibited the pro-migratory effects of CaMKK2 overexpression. DHA significantly reduced the mitochondrial ATP production and altered the arrangement of microfilaments in liver cancer cells. In addition, DHA significantly decreased the expression of CaMKK2, NCLX, ATP1A1 and ATP5H. Furthermore, by knockdown experiments of NCLX the results demonstrated that CaMKK2 downregulated the expression of ATP1A1 and ATP5H in liver cancer cells through NCLX. In conclusion, DHA may reduce ATP synthase production via the CaMKK2/NCLX signaling pathway to inhibit the invasive phenotype of liver cancer cells. It is essential to further investigate the effectiveness of DHA in the anticancer mechanism of liver cancer cells.