A Cisplatin-Loaded Immunochemotherapeutic Nanohybrid Bearing Immune Checkpoint Inhibitors for Enhanced Cervical Cancer Therapy

In Vitro Anticancer Activity of Nanoformulated Mono- and Di-nuclear Pt Compounds

Nanoformulations of mononuclear Pt complexes cis-PtCl₂ (PPh₃ )₂ (1), [Pt(PPh₃ )₂ (L-Cys)] ⋅ H₂ O (3, L-Cys=L-cysteinate), trans-PtCl₂ (PPh₂ PhNMe₂ )₂ (4; PPh₂ PhNMe₂ =4-(dimethylamine)triphenylphosphine), trans-PtI₂ (PPh₂ PhNMe₂ )₂ (5) and dinuclear Pt cluster Pt₂ (μ-S)₂ (PPh₃ )₄ (2) have comparable cytotoxicity to cisplatin against murine melanoma cell line B16F10. Masking of these discrete molecular entities within the hydrophobic core of Pluronic® F-127 significantly boosted their solubility and stability, ensuring efficient cellular uptake, giving in vitro IC₅₀ values in the range of 0.87-11.23 μM. These results highlight the potential therapeutic value of Pt complexes featuring stable Pt-P bonds in nanocomposite formulations with biocompatible amphiphilic polymers.

An ER-Targeting Iridium(III) Complex That Induces Immunogenic Cell Death in Non-Small-Cell Lung Cancer

Immunogenic cell death (ICD) is a vital component of therapeutically induced anti-tumor immunity. An iridium(III) complex (Ir1), containing an N,N-bis(2-chloroethyl)-azane derivate, as an endoplasmic reticulum-localized ICD inducer for non-small cell lung cancer (NSCLC) is reported. The characteristic discharge of damage-associated molecular patterns (DAMPs), that is, cell surface exposure of calreticulin (CRT), extracellular exclusion of high mobility group box 1 (HMGB1), and ATP, were generated by Ir1 in A549 lung cancer cells, accompanied by an increase in endoplasmic reticulum stress and reactive oxygen species (ROS). The vaccination of immunocompetent mice with Ir1-treated dying cells elicited an antitumor CD8⁺ T cell response and Foxp3⁺ T cell depletion, which eventually resulted in long-acting anti-tumor immunity by the activation of ICD in lung cancer cells. Ir1 is the first Ir-based complex that is capable of developing an immunomodulatory response by immunogenic cell death.

Biocompatible Hydrotalcite Nanohybrids for Medical Functions

Biocompatible hydrotalcite nanohybrids, i.e., layered double hydroxide (LDH) based nanohybrids have attracted significant attention for biomedical functions. Benefiting from good biocompatibility, tailored drug incorporation, high drug loading capacity, targeted cellular delivery and natural pH-responsive biodegradability, hydrotalcite nanohybrids have shown great potential in drug/gene delivery, cancer therapy and bio-imaging. This review aims to summarize recent progress of hydrotalcite nanohybrids, including the history of the hydrotalcite-like compounds for application in the medical field, synthesis, functionalization, physicochemical properties, cytotoxicity, cellular uptake mechanism, as well as their related applications in biomedicine. The potential and challenges will also be discussed for further development of LDHs both as drug delivery carriers and diagnostic agents.

Dual-functional conjugates improving cancer immunochemotherapy by inhibiting tubulin polymerization and indoleamine-2,3-dioxygenase

A series of novel conjugates comprising tublin and IDO inhibitors were designed, synthesized and evaluated for their antiproliferative activity. Among them, HI5, composed of combretastatin A-4 (CA-4) and (D)-1-methyltryptophan (D-MT) by a linker, exhibited the most potent antitumor activity, in particular with higher IC₅₀ value (0.07 μM) than CA-4 (0.21 μM) against HeLa cancer cell line. Mechanism studies indicated that HI5 can inhibit tubulin polymerization and cell migration, cause G2/M phase arrest, concurrent induce apoptosis via the mitochondrial dependent apoptosis pathway and cause reactive oxidative stress generation in HeLa cells. Furthermore, HI5 can inhibit IDO expression and decrease kynurenine production, leading to stimulating T cells activation and proliferation to enhance antitumor immunity in vitro. Interestingly, HI5 can effectively limit the tumor growth in the HeLa xenograft mice models without causing significant loss of body weight. Consequently, such a conjugation can be a potent and safe immunochemotherapeutic method for improving cancer therapy.

Diselenide-Pemetrexed Assemblies for Combined Cancer Immuno-, Radio-, and Chemotherapies

Immunotherapy has emerged as a promising new approach for cancer treatment. However, clinically available drugs have been limited until recently, and the antitumor efficacy of most cancer immunotherapies still needs to be improved. Herein, we develop diselenide-pemetrexed assemblies that combine natural killer (NK) cell-based cancer immunotherapy with radiotherapy and chemotherapy in a single system. The assemblies are prepared by co-assembly between pemetrexed and cytosine-containing diselenide through hydrogen bonds. Under γ-radiation, the hydrogen bonds are cleaved, resulting in the release of pemetrexed. At the same time, diselenide can be oxidized to seleninic acid, which suppresses the expression of human leukocyte antigen E (HLA-E) in cancer cells, thus activating the immune response of NK cells. In this way, cancer immunotherapy is combined with radiotherapy and chemotherapy, providing a new strategy for cancer treatment.

Functional Layered Double Hydroxide Nanohybrids for Biomedical Imaging

Biomedical investigations using layered double hydroxide (LDH) nanoparticles have attracted tremendous attentions due to their advantages such as biocompatibility, variable-chemical compositions, anion-exchange capacity, host-guest interactions, and crystallization-dissolution characters. Bio-imaging becomes more and more important since it allows theranostics to combine therapy and diagnosis, which is a concept of next-generation medicine. Based on the unique features mentioned above, LDHs create novel opportunities for bio-imaging and simultaneous therapy with LDHs-based nanohybrids. This review aims to explore the recent advances in multifunctional LDH nanohybrids ranging from synthesis to practical applications for various bio-imaging with therapeutic functions. Furthermore, their potential both as diagnostic agents and drug delivery carriers will be discussed with the improvement in noninvasive bio-imaging techniques.

Novel conjugates with dual suppression of glutathione S-transferases and tryptophan-2,3-dioxygenase activities for improving hepatocellular carcinoma therapy

Tryptophan-2,3-dioxygenase (TDO) is an immune checkpoint enzyme expressed in human tumors and involved in immune evasion and tumor tolerance. While glutathione S-transferases (GSTs) are pharmacological targets for several cancer. Here we demonstrated the utility of NBDHEX (GSTs inhibitor) and TDO inhibitor by the combinatorial linker design. Two novel conjugates with different linkers were prepared to reverse tumor immune suppression. The conjugates displayed significant antitumor activity against TDO and GSTs expression of HepG2 cancer cells. Further study indicated that compound 4 could induce higher apoptotic effect than its mother compounds via a mitochondrial-dependent pathway, simultaneously more effective to inhibit TDO and GSTs protein expression. Further study indicated that 4 could decrease the production of kynurenine and deactivate aryl hydrocarbon receptor (AHR), leading to CD3⁺T-cell activation and proliferation to involve in antitumor immune response.

Activation of Prodrugs by NIR-Triggered Release of Exogenous Enzymes for Locoregional Chemo-photothermal Therapy

Enzymes have been used to direct the conversion of prodrugs in cancer therapy. However, non-specific distribution of endogenous enzymes seriously hinders their bioapplications. Herein, we developed a near-infrared-triggered locoregional chemo-photothermal therapy based on the exogenous enzyme delivery and remolded tumor mivroenvironment. The catalytic efficiency of enzymes was enhanced by the hyperthermia, and the therapeutic efficacy of photothermal therapy (PTT) was improved owing to the inhibition of heat shock protein 90 by chemotherapeutics. The locoregional chemo-phototherapy achieved a one-time successful cure in 4T1 tumor-bearing mice model. Thus, a mutually reinforcing feedback loop between PTT and chemotherapy can be initiated by the irradiation, which holds a promising future in cancer therapy.

Multifunctional platinum(IV) complexes as immunostimulatory agents to promote cancer immunochemotherapy by inhibiting tryptophan-2,3-dioxygenase

Increasing evidences suggested that cisplatin can be involved in a tumor-specific immune response as an immunomodulator to improve antitumor immunity, but the designation and development are limited. Here, we report a series of novel Pt(IV) complexes derived from the conjugation of platinum(II) anticancer agents with an immune checkpoint TDO inhibitor. These complexes not only showed significant cytotoxic effects on the tested cancer cell lines, but also could enhance antitumor immune response. Particularly, complex T2, the mono-conjuagte of oxoplatin and (E)-4-oxo-4-(3-(2-(pyridin-3-yl)vinyl)-1H-indol-1-yl)butanoic acid, displayed 35-fold more potency than cisplatin against TDO-overexpressed HepG-2 cancer cells. Further study indicated that T2 could inhibit TDO via releasing a derivative of a TDO inhibitor and block kynurenine production, resulting in T-cell activation and proliferation in vitro. In vivo tests proved that T2 as a potent immunomodulator could highly promote the antitumor activity of cisplatin and effectively suppress the expression of TDO. This immunochemotherapeutic strategy can be promisingly applied to treat with TDO-overexpressed cancers.