Pt(IV) Prodrugs with Non-Steroidal Anti-inflammatory Drugs in the Axial Position

Repaglinide platinum(IV) conjugates: Enhancing p53 signaling for antitumor and antimetastatic efficacy

The tumor suppressor p53 plays multiple roles at the crossroads of suppressing tumor development and metastasis. Here, a series of Repaglinide platinum(IV) conjugates promoting the p53 pathway were designed and prepared, which displayed potent antiproliferative and antimetastatic activities both in vitro and in vivo. Mechanistically, the expression of p53 was upregulated by the synergistic functions of the platinum core through causing severe DNA damage, and the RPG ligand via stimulating the lumican/p53/p21 pathway. The mitochondria-mediated apoptosis was initiated, involving the Bcl-2/Bax/caspase pathway. Pro-death autophagy was initiated with the upregulation of LC3II and down regulation of p62. Additionally, angiogenesis was suppressed by reversing tumor inflammation through the inhibition of key enzymes COX-2, MMP9, and VEGFA. Furthermore, antitumor immunity was enhanced by blocking the immune checkpoint PD-L1, which led to an increased presence of CD3+ and CD8+ T-cells within the tumor microenvironment.

Pt(IV)-PROTAC Complexes with Synergistic Antitumor Activity and Enhanced Membrane Permeability

A class of Pt(IV)-PROTAC complexes was designed and synthesized with dual aims of inducing DNA strand damage and inhibiting DNA repair. These complexes showed good antiproliferative activity against a range of cancer cell lines. Enhanced intracellular uptake of platinum and PROTAC was observed. Multiple mechanisms of action were identified, including the induction of DNA damage, disruption of DNA repair, and activation of mitochondrial-dependent apoptosis. One of the Pt(IV)-PROTACs, CW-2, showed excellent antitumor activity in a xenograft mouse model. These results suggest that Pt(IV)-PROTAC represents a promising strategy for the development of novel antitumor therapeutics.

Nanostructured mesoporous silica carriers for platinum-based conjugates with anti-inflammatory agents

This review discusses the relationship between inflammation and cancer initiation and progression, which has prompted research into anti-inflammatory approaches for cancer prevention and treatment. Specifically, it focuses on the use of inflammation-reducing agents to enhance the effectiveness of tumor treatment methods. These agents are combined with platinum(II)-based antitumor drugs to create multifunctional platinum(IV) prodrugs, allowing for simultaneous delivery to tumor cells in a specific ratio. Once inside the cells and subjected to intracellular reduction, both components can act in parallel through distinct pathways. Motivated by the objective of reducing the systemic toxicity associated with contemporary chemotherapy, and with the aim of leveraging the passive enhanced permeability and retention effect exhibited by nanostructured materials to improve their accumulation within tumor tissues, the platinum(IV) complexes have been efficiently loaded into mesoporous silica SBA-15 material. The resulting nanostructured materials are capable of providing controlled release of the conjugates when subjected to simulated plasma conditions. This feature suggests the potential for extended circulation within the body in vivo, with minimal premature release of the drug before reaching the intended target site. The primary emphasis of this review is on research that integrates these two approaches to develop chemotherapeutic treatments that are both more efficient and less harmful.

Ciclopirox platinum(IV) conjugates suppress tumors by promoting mitophagy and provoking immune responses

Mitophagy is an important target for antitumor drugs development. A series of ciclopirox (CPX) platinum(IV) hybrids targeting PTEN induced putative kinase 1 (PINK1)/Parkin mediated mitophagy were designed and prepared as antitumor agents. The dual CPX platinum(IV) complex with cisplatin core was screened out as a candidate, which displayed promising antitumor activities both in vitro and in vivo. Mechanistically, it caused serious DNA damage in tumor cells. Then, remarkable mitochondrial damage was induced accompanied by the mitochondrial membrane depolarization and reactive oxygen species generation, which further promoted apoptosis through the Bcl-2/Bax/Caspase3 pathway. Furthermore, mitophagy was ignited via the PINK1/Parkin/P62/LC3 axis, and exhibited positive influence on promoting the apoptosis of tumor cells. The antitumor immunity was boosted by the block of immune check point programmed cell death ligand-1 (PD-L1), which further increased the density of T cells in tumors. Subsequently, the metastasis of tumor cells was inhibited by inhibiting angiogenesis in tumors.

Gold(I) Complexes Based on Nonsteroidal Anti-Inflammatory Derivatives as Multi-Target Drugs against Colon Cancer

Targeting inflammation and the molecules involved in the inflammatory process could be an effective cancer prevention and therapy strategy. Therefore, the use of anti-inflammatory strategies, such as NSAIDs and metal-based drugs, has become a promising approach for preventing and treating cancer by targeting multiple pathways involved in tumor progression. The present work describes new phosphane gold(I) complexes derived from nonsteroidal anti-inflammatory drugs as multitarget drugs against colon cancer. The antiproliferative effect of the most active complexes, [Au(L3)(JohnPhos)] (3b), [Au(L4)(CyJohnPhos)] (4a) and [Au(L4)(JohnPhos)] (4b) against colon cancer cells (Caco2-/TC7) seems to be mediated by the inhibition of the enzyme cyclooxygenase-1/2, modulation of reactive oxygen species levels by targeting thioredoxin reductase (TrxR) activity, and induction of apoptosis in cancer cells. Additionally, the three complexes exhibit high selectivity index values toward noncancerous cells. The research highlights the importance of maintaining cellular redox balance and the role of TrxR in cancer cell survival.

Advancements in platinum-based anticancer drug development: A comprehensive review of strategies, discoveries, and future perspectives

Platinum-based anticancer drugs have been at the forefront of cancer chemotherapy, with cisplatin emerging as a pioneer in the treatment of various malignancies. This review article provides a comprehensive overview of the evolution of platinum-based anticancer therapeutics, focusing on the development of cisplatin, platinum(IV) prodrugs, and the integration of photodynamic therapy (PDT) for enhanced cancer treatment results. The first section of the review delves into the historical context and molecular mechanisms underlying the success of cisplatin, highlighting its DNA binding properties and subsequent interference with cellular processes. Despite its clinical efficacy, the inherent limitations, including dose-dependent toxicities and acquired resistance, accelerated the exploration of novel platinum derivatives. This led to the emergence of platinum(IV) prodrugs, designed to overcome resistance mechanisms and enhance selectivity through targeted drug delivery. The subsequent section provides an in-depth analysis of the principles of design and structural modifications employed in the development of platinum(IV) prodrugs. The transitions to the incorporation of photodynamic therapy (PDT) stands out as a synergistic approach to platinum-based anticancer treatment. The photophysical properties of platinum complexes are discussed in the context of their potential application in PDT, emphasizing on combined cytotoxic effects of platinum-based drugs and light-induced reactive oxygen species generation. This dual-action approach holds great promise for overcoming the limitations of traditional chemotherapy as well as producing superior therapeutic outcomes. Overall, the present report explores the latest developments in the development and use of platinum complexes, highlighting novel strategies such combination treatments, targeted delivery methods, and the generation of multifunctional complexes. It also provides a comprehensive overview of the current landscape while proposing future directions for the development of next-generation platinum-based anticancer therapeutics.

Transferrin-Modified Carprofen Platinum(IV) Nanoparticles as Antimetastasis Agents with Tumor Targeting, Inflammation Inhibition, Epithelial-Mesenchymal Transition Suppression, and Immune Activation Properties

The inflammatory microenvironment is a central driver of tumor metastasis, intimately associated with the promotion of epithelial-mesenchymal transition (EMT) and immune suppression. Here, transferrin-modified carprofen platinum(IV) nanoparticles Tf-NPs@CPF2-Pt(IV) with promising antiproliferative and antimetastatic properties were developed, which activated by inhibiting inflammation, suppressing EMT, and activating immune responses besides causing DNA injury. The nanoparticles released the active ingredient CPF2-Pt(IV) in a sustained manner and offered enhanced pharmacokinetic properties compared to free CPF2-Pt(IV) in vivo. Additionally, they possessed satisfactory tumor targeting effects via the transferrin motif. Serious DNA damage was induced with the upregulation of γ-H2AX and P53, and the mitochondria-mediated apoptotic pathway Bcl-2/Bax/caspase3 was initiated. Inflammation was alleviated by inhibiting COX-2 and MMP9 and decreasing inflammatory cytokines TNF-α and IL-6. Subsequently, the EMT was reversed by inhibiting the Wnt/β-catenin pathway. Furthermore, the antitumor immunity was provoked by blocking the immune checkpoint PD-L1 and increasing CD3+ and CD8+ T lymphocytes in tumors.

Pt(iv) derivatives of cisplatin and oxaliplatin bearing an EMT-related TMEM16A/COX-2-selective dual inhibitor against colorectal cancer cells HCT116

Colorectal cancer represents the over-expression of TMEM16A and COX-2, offering a promising therapeutic strategy. Two Pt(iv) conjugates derived from Pt(ii) drug (cisplatin or oxaliplatin) and niflumic acid, complexes 1 and 2, were designed and prepared to exert the positive impact of multiple biological targets of DNA/TMEM16A/COX-2 against colorectal cancer. Complex 2 afforded higher cytotoxicity than 1 and the combination of an intermediate of oxidized oxaliplatin and NFA against cancer cells A549, HeLa, MCF-7, and HCT116. Especially for colorectal cancer cells HCT116, 2 was significantly more toxic (22-fold) and selective to cancer cells against normal HUVEC cells (4-fold) than first-line oxaliplatin. The outstanding anticancer activity of 2 is partly attributed to its dramatic increase in cellular uptake, DNA damage, and apoptosis. Mechanistic studies indicated that 2 inhibited HCT116 cell metastasis by triggering TMEM16A, COX-2, and their downstream signaling pathways, including EGFR, STAT3, E-cadherin and N-cadherin.

Iridium(III) complexes conjugated with naproxen exhibit potent anti-tumor activities by inducing mitochondrial damage, modulating inflammation, and enhancing immunity

A series of Ir(III)-naproxen (NPX) conjugates with the molecular formula [Ir(C^N)2bpy(4-CH2ONPX-4'-CH2ONPX)](PF6) (Ir-NPX-1-3) were designed and synthesized, including C^N = 2-phenylpyridine (ppy, Ir-NPX-1), 2-(2-thienyl)pyridine (thpy, Ir-NPX-2) and 2-(2,4-difluorophenyl)pyridine (dfppy, Ir-NPX-3). Cytotoxicity tests showed that Ir-NPX-1-3 exhibited excellent antitumor activity, especially in A549R cells. The cellular uptake experiment showed that the complexes were mainly localized in mitochondria, and induced apoptosis in A549R cells by damaging the structure and function of mitochondria. The main manifestations are a decrease in the mitochondrial membrane potential (MMP), an increase in reactive oxygen species (ROS) levels, and cell cycle arrest. Furthermore, Ir-NPX-1-3 could inhibit the migration and colony formation of cancer cells, demonstrating potential anti-metastatic ability. Finally, the anti-inflammatory and immunological applications of Ir-NPX-1-3 were verified. The downregulation of cyclooxygenase-2 (COX-2) and programmed death-ligand 1 (PD-L1) expression levels and the release of immunogenic cell death (ICD) related signaling molecules such as damage-associated molecular patterns (DAMPs) (cell surface calreticulin (CRT), high mobility group box 1 (HMGB1), and adenosine triphosphate (ATP)) indicate that these Ir(III) -NPX conjugates are novel ICD inducers with synergistic effects in multiple anti-tumor pathways.

Light-Responsive Pt(IV) Prodrugs with Controlled Photoactivation and Low Dark Toxicity

Light-induced release of cisplatin from Pt(IV) prodrugs represents a promising approach for precise control over the antiproliferative activity of Pt-based chemotherapeutic drugs. This method has the potential to overcome crucial drawbacks of conventional cisplatin therapy, such as high general toxicity toward healthy organs and tissues. Herein, we report two Pt(IV) prodrugs with BODIPY-based photoactive ligands Pt-1 and Pt-2, which were designed using carbamate and triazole linkers, respectively. Both prodrugs demonstrated the ability to release cisplatin under blue light irradiation without the requirement of an external reducing agent. Dicarboxylated Pt-2 prodrug turned out to be more stable in the dark and more sensitive to light than its monocarbamate Pt-1 counterpart; these observations were explained using DFT calculations. The investigation of the photoreduction mechanism of Pt-1 and Pt-2 prodrugs using DFT modeling and ΔG0 PET estimation suggests that the photoinduced electron transfer from the singlet excited state of the BODIPY axial ligand to the Pt(IV) center is the key step in the light-induced release of cisplatin from the complexes. Cytotoxicity studies demonstrated that both prodrugs were nontoxic in the dark and toxic to MCF-7 cells under low-dose irradiation with blue light, and the observed effect was solely due to the cisplatin release from the Pt(IV) prodrugs. Our research presents an elegant synthetic approach to light-activated Pt(IV) prodrugs and presents findings that may contribute to the future rational design of photoactivatable Pt(IV) prodrugs.

Pt(IV) Complexes in the Search for Novel Platinum Prodrugs with Promising Activity

The kinetically inert, six coordinated, octahedral Pt(IV) complexes are termed dual-, triple-, or multi-action prodrugs based on the nature of the axially substituted ligands. These ligands are either inert or biologically active, where the nature of these axial ligands provides additional stability, synergistic biological activity or cell-targeting ability. There are many literature reports from each of these classes, mentioning the varied nature of these axial ligands. The ligands comprise drug molecules such as chlorambucil, doxorubicin, valproic acid, ethacrynic acid, biologically active chalcone, coumarin, combretastatin, non-steroidal anti-inflammatory drugs (NSAIDs) and many more, potentiating the anti-proliferative profile or reducing the side effects associated with cisplatin therapy. The targeting and non-targeting nature of these moieties exert additive or synergistic effects on the anti-cancer activity of Pt(II) moieties. Herein, we discuss the effects of these axially oriented ligands and the changes in the non-leaving am(m)ine groups and in the leaving groups on the biological activity. In this review, we have presented the latest developments in the field of Pt(IV) complexes that display promising activity with a reduced resistance profile. We have discussed the structure activity relationship (SAR) and the effects of the ligands on the biological activity of Pt(IV) complexes with cisplatin, oxaliplatin, carboplatin and the Pt core other than approved drugs. This literature work will help researchers to get an idea about Pt(IV) complexes that have been classified based on the aspects of their biological activity.

A Dual Stimuli-Responsive Nanoplatform Loaded PtIV -Triptolide Prodrug for Achieving Synergistic Therapy toward Breast Cancer

To strengthen the antitumor efficacy and avoid toxicity to normal cells of cisplatin and triptolide, herein, an acid and glutathione (GSH) dual-controlled nanoplatform for enhanced cancer treatment through the synergy of both "1+1" apoptosis and "1+1" ferroptosis is designed. Remarkably, ZIF8 in response to tumor microenvironment enhances drug targeting and protects drugs from premature degradation. Meanwhile, the PtIV  center can be easily reduced to cisplatin because of the large amount of GSH, thus liberating the triptolide as the coordinated ligand. The released cisplatin and hemin in turn boost the tumor cell "1+1" apoptosis through chemotherapy and photodynamic therapy, respectively. Furthermore, GSH reduction through PtIV  weakens the activation of glutathione peroxidase 4 (GPX4) effectively. The released triptolide can inhibit the expressions of GSH by regulating nuclear factor E2 related factor 2 (Nrf2), further promoting membrane lipid peroxidation, thus "1+1" ferroptosis can be achieved. Both in vitro and in vivo results demonstrate that the nanosystem can not only perform superior specificity and therapeutic outcomes but also reduce the toxicity to normal cells/tissues of cisplatin and triptolide effectively. Overall, the prodrug-based smart system provides an efficient therapeutic strategy for cancer treatment by virtue of the effect of enhanced "1+1" apoptosis and "1+1" ferroptosis therapies.

Pyrenebutyrate Pt(IV) Complexes with Nanomolar Anticancer Activity

Research on platinum-based anticancer drugs continuously strives to develop new non-classical platinum complexes. Pt(IV) prodrugs are the most promising, and their activation-by-reduction mechanism of action is being explored as a prospect for higher selectivity and efficiency. Herein, we present the anticancer potency and chemical reactivity of Pt(IV) complexes formed by linking pyrene butyric acid with cisplatin. The results from cytotoxicity screening on 10 types of cancer cell lines and non-malignant cells (HEK-293) indicated IC50 values as low as 50-70 nM for the monosubstituted Pt(IV) complex against leukemia cell lines (HL-60 and SKW3) and a cisplatin-resistant derivative (HL-60/CDDP). Interestingly, the bis-substituted complex is virtually non-toxic to both healthy and cancerous cells of adherent types. Nevertheless, it shows high cytotoxicity against multidrug-resistant derivatives HL-60/CDDP and HL-60/Dox. The reactivity of the complexes with biological reductants was monitored by the NMR method. Furthermore, the platinum uptake by the treated cells was examined on two types of cellular cultures: adherent and suspension growing, and proteome profiling was conducted to track expression changes of key apoptosis-related proteins in HL-60 cells. The general conclusion points to a possible cytoskeletal entrapment of the bulkier bis-pyrene complex that could be limiting its cytotoxicity to adherent cells, both cancerous and healthy ones.

Regulating tumor glycometabolism and the immune microenvironment by inhibiting lactate dehydrogenase with platinum(iv) complexes

Lactate dehydrogenase (LDH) is a key enzyme involved in the process of glycolysis, assisting cancer cells to take in glucose and generate lactate, as well as to suppress and evade the immune system by altering the tumor microenvironment (TME). Platinum(iv) complexes MDP and DDP were prepared by modifying cisplatin with diclofenac at the axial position(s). These complexes exhibited potent antiproliferative activity against a panel of human cancer cell lines. In particular, DDP downregulated the expression of LDHA, LDHB, and MCTs to inhibit the production and influx/efflux of lactate in cancer cells, impeding both glycolysis and glucose oxidation. MDP and DDP also reduced the expression of HIF-1α, ARG1 and VEGF, thereby disrupting the formation of tumor vasculature. Furthermore, they promoted the repolarization of macrophages from the tumor-supportive M2 phenotype to the tumor-suppressive M1 phenotype in the TME, thus enhancing the antitumor immune response. The antitumor mechanism involves reprogramming the energy metabolism of tumor cells and relieving the immunosuppressive TME.

Platinum(IV) Derivatives of [Pt(1S,2S-diaminocyclohexane)(5,6-dimethyl-1,10-phenanthroline)] with Diclofenac Ligands in the Axial Positions: A New Class of Potent Multi-action Agents Exhibiting Selectivity to Cancer Cells

The platinum(II) complex [Pt(1S,2S-diaminocyclohexane)(5,6-dimethyl-1,10-phenanthroline)]²⁺ (Pt^II56MeSS, 1) exhibits high potency across numerous cancer cell lines acting by a multimodal mechanism. However, 1 also displays side toxicity and in vivo activity; all details of its mechanism of action are not entirely clear. Here, we describe the synthesis and biological properties of new platinum(IV) prodrugs that combine 1 with one or two axially coordinated molecules of diclofenac (DCF), a non-steroidal anti-inflammatory cancer-selective drug. The results suggest that these Pt(IV) complexes exhibit mechanisms of action typical for Pt(II) complex 1 and DCF, simultaneously. The presence of DCF ligand(s) in the Pt(IV) complexes promotes the antiproliferative activity and selectivity of 1 by inhibiting lactate transporters, resulting in blockage of the glycolytic process and impairment of mitochondrial potential. Additionally, the investigated Pt(IV) complexes selectively induce cell death in cancer cells, and the Pt(IV) complexes containing DCF ligands induce hallmarks of immunogenic cell death in cancer cells.

Multi-action platinum(IV) prodrugs conjugated with COX-inhibiting NSAIDs

In the last decades, inflammation has been recognized as being closely connected to cancer, and joint strategies encompassing chemotherapeutic and anti-inflammatory agents have been extensively studied. In this work, a series of novel cisplatin and oxaliplatin-based Pt(IV) complexes comprising non-steroidal anti-inflammatory drugs (NSAIDs) and their carboxyl ester analogues as axial moieties were synthesized. Several of the cisplatin-based Pt(IV) complexes 22-30 showed increased cytotoxicity in the human cancer cell lines CH1/PA-1, SW480 and A549 compared to the Pt(II) drug. For the most potent complex 26, comprising two aceclofenac (AFC) moieties, the formation of Pt(II)-9-methylguanine (9-MeG) adducts after activation with ascorbic acid (AsA) was proven. Additionally, a significant inhibition of cyclooxygenase (COX) activity and prostaglandin E₂ (PGE₂) production was observed, as well as increased cellular accumulation, depolarization of mitochondrial membranes, and strong proapoptotic potencies in SW480 cells. Overall, these systematic effects shown in vitro confer 26 as a potential anticancer agent combined with anti-inflammatory properties.

Versatile Platinum(IV) Prodrugs of Naproxen and Acemetacin as Chemo-Anti-Inflammatory Agents

Developing new and versatile platinum(IV) complexes that incorporate bioactive moieties is a rapidly evolving research strategy for cancer drug discovery. In this study, six platinum(IV) complexes (1-6) that are mono-substituted in the axial position with a non-steroidal anti-inflammatory molecule, naproxen or acemetacin, were synthesised. A combination of spectroscopic and spectrometric techniques confirmed the composition and homogeneity of 1-6. The antitumour potential of the resultant complexes was assessed on multiple cell lines and proved to be significantly improved compared with cisplatin, oxaliplatin and carboplatin. The platinum(IV) derivatives conjugated with acemetacin (5 and 6) were determined to be the most biologically potent, demonstrating GI₅₀ values ranging between 0.22 and 250 nM. Remarkably, in the Du145 prostate cell line, 6 elicited a GI₅₀ value of 0.22 nM, which is 5450-fold more potent than cisplatin. A progressive decrease in reactive oxygen species and mitochondrial activity was observed for 1-6 in the HT29 colon cell line, up to 72 h. The inhibition of the cyclooxygenase-2 enzyme was also demonstrated by the complexes, confirming that these platinum(IV) complexes may reduce COX-2-dependent inflammation and cancer cell resistance to chemotherapy.

Photoinduced Reduction of Novel Dual-Action Riboplatin Pt(IV) Prodrug

Controlled photoreduction of Pt(IV) prodrugs is a challenging task due to the possibility of targeted light-controlled activation of anticancer agents without affecting healthy tissues. Also, a conjugation of photosensitizers and clinically used platinum drugs into one Pt(IV) prodrug allows combining photodynamic therapy and chemotherapy approaches into one molecule. Herein, we designed the cisplatin-based Pt(IV) prodrug Riboplatin with tetraacetylriboflavin in the axial position. A novel Pt(IV) prodrug is able to act both as a photodynamic therapy (PDT) agent through the conversion of ground-state ³O₂ to excited-state ¹O₂ and as an agent of photoactivated chemotherapy (PACT) through releasing of cisplatin under gentle blue light irradiation, without the requirement of a reducing agent. The light-induced behavior of Riboplatin was investigated using an electrochemical sensor in MCF-7 tumor spheroids. Photocontrolled cisplatin release and ROS generation were detected electrochemically in real time. This appears to be the first confirmation of simultaneous photoactivated release of anticancer drug cisplatin and ROS from a dual-action Pt(IV) prodrug observed from the inside of living tumor spheroids.

Biotinylated Pt(IV) prodrugs with elevated lipophilicity and cytotoxicity

A design of Pt(IV) prodrugs with tumor cell targeting moieties leading to increased selectivity is of interest. Herein, we designed a novel Pt(IV) prodrugs with COX-inhibitor naproxen, long-chain hydrophobic stearic acid moiety and biotin as axial ligands. We have established that for Pt(IV) prodrugs with biotin and naproxen or stearate in axial position, the lipophilicity rather than biotin receptors expression is the main factor of cytotoxicity. We also monitored the reduction speed of Pt(IV) prodrug 3 with naproxen and biotin in axial positions in A549 cells using XANES and demonstrated that the prodrug gradually releases cisplatin within 20 hours of incubation.

2: A Novel Potent Platinum(IV) Prodrug Enhances Chemo-Immunotherapy by Facilitating PD-L1 Degradation in the Cytoplasm and Cytomembrane

Platinum drugs as primary chemotherapy drugs have been applied to various cancer patients. However, their therapeutic applicability is limited due to the adverse effects and immunosuppression. To minimize the side effects and boost the immune response, we designed and synthesized platinum(IV) prodrugs that introduced BRD4 inhibitor JQ-1. Among them, CJ2 had the most potent therapeutic activity and less toxicity. With the introduction of ligand JQ-1, CJ2-reduced PD-L1 protein was found in the cytoplasm and cytomembrane for the first time. By interfering with the PD-L1 synthesis, CJ2 could arouse the immune system and promote CD8+ T cell infiltration. Meanwhile, CJ2 could accelerate PD-L1 degradation in the cytoplasm to block DNA damage repair. In vivo, CJ2 markedly suppressed tumor growth by reversing the immunosuppression microenvironment and enhancing DNA damage. These findings provide an effective approach to improve the selectivity and activity of the platinum drugs with elevated immune response.

Recent Advances in Light-Controlled Activation of Pt(IV) Prodrugs

Pt(IV) prodrugs remain one of the most promising alternatives to conventional Pt(II) therapy due to their versatility in axial ligand choice and delayed mode of action. Selective activation from an external source is especially attractive due to the opportunity to control the activity of an antitumor drug in space and time and avoid damage to normal tissues. In this review, we discuss recent advances in photoabsorber-mediated photocontrollable activation of Pt(IV) prodrugs. Two main approaches developed are the focus of the review. The first one is the photocatalytic strategy based on the flavin derivatives that are not covalently bound to the Pt(IV) substrate. The second one is the conjugation of photoactive molecules with the Pt(II) drug via axial position, yielding dual-action Pt(IV) molecules capable of the controllable release of Pt(II) cytotoxic agents. Thus, Pt(IV) prodrugs with a light-controlled mode of activation are non-toxic in the absence of light, but show high antiproliferative activity when irradiated. The susceptibility of Pt(IV) prodrugs to photoreduction, photoactivation mechanisms, and biological activity is considered in this review.

Nano- and Microsensors for In Vivo Real-Time Electrochemical Analysis: Present and Future Perspectives

Electrochemical nano- and microsensors have been a useful tool for measuring different analytes because of their small size, sensitivity, and favorable electrochemical properties. Using such sensors, it is possible to study physiological mechanisms at the cellular, tissue, and organ levels and determine the state of health and diseases. In this review, we highlight recent advances in the application of electrochemical sensors for measuring neurotransmitters, oxygen, ascorbate, drugs, pH values, and other analytes in vivo. The evolution of electrochemical sensors is discussed, with a particular focus on the development of significant fabrication schemes. Finally, we highlight the extensive applications of electrochemical sensors in medicine and biological science.

Electrochemical Detection of a Novel Pt(IV) Prodrug with the Metronidazole Axial Ligand in the Hypoxic Area

We report herein a Pt(IV) prodrug with metronidazole in axial positions Pt-Mnz. The nitroaromatic axial ligand was conjugated with a cisplatin scaffold to irreversibly reduce under hypoxic conditions, thereby retaining the Pt(IV) prodrug in the area of hypoxia. X-ray near-edge adsorption spectroscopy (XANES) on dried drug-preincubated tumor cell samples revealed a gradual release of cisplatin from the Pt-Mnz prodrug instead of rapid intracellular degradation. The ability of the prodrug to penetrate into three-dimensional (3D) spheroid cellular cultures was evaluated by a novel electrochemical assay via a platinum-coated carbon nanoelectrode, capable of single-cell measurements. Using a unique technique of electrochemical measurements in single tumor spheroids, we were able to both detect the real-time response of the axial ligand to hypoxia and establish the depth of penetration of the drug into the tumor model.