Iridium nanozyme-mediated photoacoustic imaging-guided NIR-II photothermal therapy and tumor microenvironment regulation for targeted eradication of cancer stem cells

Cancer stem cells (CSCs) are found in many solid tumors, which play decisive roles in the occurrence, recurrence and metastasis of tumors. However, drugs are difficult to kill CSCs due to their limited number and location in oxygen-deprived tissue far from the blood vessels. Meanwhile, the survival and stemness maintenance of CSCs strongly depend on the tumor microenvironment (TME). Herein, we developed a CD44 antibody modified iridium nanosheet with enzyme-like activity (defined as Ir Nts-Ab) that effectively eradicates CSCs for cancer therapy. We observe that Ir Nts-Ab can enrich tumor tissues to remove excessive reactive oxygen species and produce oxygen, thus alleviating hypoxia and the inflammatory TME to reduce the proportion of CSCs and inhibit metastasis. In addition, Ir Nts-Ab targets CSCs and normal cancer cells with near infrared II-region photothermal therapy (NIR-II PTT), and is easily taken up by CSCs due to recognition of the CD44 proteins. Moreover, photoacoustic imaging helps monitor drug accumulation and hypoxic TME improvement in tumor tissue. Importantly, Ir Nts-Ab has good biological safety, making it suitable for biomedical applications. This iridium nanozyme based on TME regulation as well as NIR-II PTT will be a promising strategy for the treatment of cancer. STATEMENT OF SIGNIFICANCE: Cancer stem cells (CSCs) are key factors that make tumors difficult to eradicate, and strongly depend on the hypoxic tumor microenvironment (TME), which plays a crucial role in the occurrence and metastasis of tumors. Herein, an antibody modified iridium nanosheet (definition as Ir Nts-Ab) was developed for targeted eradication of CSCs by photoacoustic imaging guided photothermal therapy (PTT) and TME regulation. Ir Nts-Ab with catalase-like activity could inhibit HIF-1α by producing oxygen, thus effectively reducing the proportion of CSCs and inhibiting tumor metastasis. Additionally, Ir Nts-Ab achieved the eradication of CSCs by PTT, and eliminated reactive oxygen species to decrease the inflammatory response, resulting in reduced tumor metastasis, which was promising for the cure of solid tumors in the clinics.

Microfluidic synthesis of fibronectin-coated polydopamine nanocomplexes for self-supplementing tumor microenvironment regulation and MR imaging-guided chemo-chemodynamic-immune therapy

Development of nanomedicines to overcome the hindrances of tumor microenvironment (TME) for tumor theranostics with alleviated side effects remains challenging. We report here a microfluidic synthesis of artesunate (ART)-loaded polydopamine (PDA)/iron (Fe) nanocomplexes (NCs) coated with fibronectin (FN). The created multifunctional Fe-PDA@ART/FN NCs (FDRF NCs) with a mean size of 161.0 ​nm exhibit desired colloidal stability, monodispersity, r₁ relaxivity (4.96 ​mM^-1s^-1), and biocompatibility. The co-delivery of the Fe²⁺ and ART enables enhanced chemodynamic therapy (CDT) through improved intracellular reactive oxygen species generation via a cycling reaction between Fe³⁺ and Fe²⁺ caused by the Fe³⁺-mediated glutathione oxidation and Fe²⁺-mediated ART reduction/Fenton reaction for self-supplementing TME regulation. Likewise, the combination of ART-mediated chemotherapy and the Fe²⁺/ART-regulated enhanced CDT enables noticeable immunogenic cell death, which can be collaborated with antibody-mediated immune checkpoint blockade to exert immunotherapy having significant antitumor immunity. The combined therapy improves the efficacy of primary tumor therapy and tumor metastasis inhibition by virtue of FN-mediated specific targeting of FDRF NCs to tumors with highly expressed α_vβ₃ integrin and can be guided through the Fe(III)-rendered magnetic resonance (MR) imaging. The developed FDRF NCs may be regarded as an advanced nanomedicine formulation for chemo-chemodynamic-immune therapy of different tumor types under MR imaging guidance.

Mn-Si-based nanoparticles-enhanced inhibitory effect on tumor growth and metastasis in photo-immunotherapy

The anticancer effect of phototherapy has been limited by some factors, including the easy degradation of photo agents, the complex tumor microenvironment, and the limited immune activation capacity, which impedes its efficiency in inhibiting tumor growth and tumor metastasis. Herein, Mn-doped mesoporous silica nanoparticles were synthesized to load the photo agent of IR 780, which were further coated with Mn (IMM). Notably, the combination of IMM and an 808 nm laser irradiation simultaneously inhibited the growth of primary tumors and distant untreated tumors in a bilateral animal model, which could be attributed to the protection of IMM to IR 780, the regulation functions to the tumor microenvironment, as well as the enhanced immune activation capacity. This work highlighted an alternative strategy for enhancing the inhibitory effect on both tumor growth and tumor metastasis in the combinational anticancer therapy of phototherapy and immunotherapy (photo-immunotherapy).

The role of Platinum(IV)-based antitumor drugs and the anticancer immune response in medicinal inorganic chemistry. A systematic review from 2017 to 2022

Platinum-based antitumor drugs have been used in many types of tumors due to its broad antitumor spectrum in clinic. Encouraged by the cisplatin's (CDDP) worldwide success in cancer chemotherapy, the research in platinum-based antitumor drugs has evolved from traditional platinum drug to multi-ligand and multifunctional platinum prodrugs over half a century. With the rapid development of metal drugs and the anticancer immune response, challenges and opportunities in platinum drug research have been shifted from traditional platinum-based drugs to platinum-based hybrids and the direction of development is tending toward photodynamic therapy, nano-delivery therapy, drug combination, targeted therapy, diagnostic therapy, immune-combination therapy and tumor stem cell therapy. In this review, we first exhaustively overviewed the role of platinum-based antitumor prodrugs and the anticancer immune response in medicinal inorganic chemistry based on the special nanomaterials, the modification of specific ligands, and the multiple functions obtained that are beneficial for tumor therapy in the last five years. We also categorized them according to drug potency and function. There hasn't been a comprehensive evaluation of precursor platinum drugs in prior articles. And a multifarious approach to distinguish and detail the variety of alterations of platinum-based precursors in various valence states also hasn't been summarized. In addition, this review points out the main problems at the interface of chemistry, biology, and medicine from their action mechanisms for current platinum drug development, and provides up-to-date potential strategies from drug design perspectives to circumvent those drawbacks. And a promising idea is also enlightened for researchers in the development and discovery of platinum prodrugs.

Tumor microenvironment regulation - enhanced radio - immunotherapy

Radiotherapy (RT) is frequently utilized for cancer treatment in clinical practice and has been proved to have immune stimulation potency in recent years. However, its inhibitory effect on tumor growth, especially on tumor metastasis, is still limited by many factors, including the complex tumor microenvironment (TME). Therefore, the TME - regulating SiO₂@MnO₂ nanoparticles (SM NPs) were prepared and applied to the combination of RT and immunotherapy. In a bilateral animal model, SM NPs not only enhanced the inhibitory effect of RT on primary tumor growth, but also strengthened the abscopal effect to inhibit the growth of distant untreated tumors. As for the distant untreated tumor, 40% of mice showed complete inhibition of tumor growth and 40% showed a suppressed tumor growth. Moreover, SM NPs showed modulation functions for TME through inducing the increase in intracellular levels of oxygen and reactive oxygen species after their reaction with hydrogen peroxide and the main antioxidative agent glutathione in TME. Lastly, SM NPs also effectively induced the increase in the amounts of cytokines secreted by macrophage - like cells, indicating modulation functions for immune responses. This work highlighted a potential strategy of simultaneously inhibiting tumor growth and metastasis through the regulation of TME and immune responses by SM NPs - enhanced radio - immunotherapy.